Author name code: vazquez ADS astronomy entries on 2022-09-14 author:"Vazquez, Manolo" ------------------------------------------------------------------------ Title: Ka-Band Monopulse Antenna Pointing Calibration Using Wideband Radio Sources Authors: Buu, C.; Calvo, J.; Cheng, T. -H.; Vazquez, M. Bibcode: 2010IPNPR.182A...1B Altcode: A new method of performing a system end-to-end monopulse antenna calibration using widely available wideband astronomical radio sources is presented as an alternative to the current method of using a spacecraft signal. Current monopulse calibration requires a spacecraft carrier signal to measure amplitude and phase differences in the monopulse feed and low-noise amplifiers (LNAs). The alternative method presented here will allow the ground station to perform monopulse calibrations during maintenance periods instead of spacecraft track time, and provide an end-to-end system check-out capability without requiring a spacecraft signal. In this article, we give an overview of the current calibration approach, describe a new method for calibrating with radio sources, and present results from field testing of this new method. Title: Studies of CSS/GPS sources with the Deep Space Network antennas in Madrid Authors: Garcia-Miro, C.; Moll, E.; Vazquez, M.; Kuiper, T. B. H. Bibcode: 2009AN....330..137G Altcode: This contribution summarizes the antennas and receivers available at the Madrid Deep Space Communication Complex (MDSCC) and outlines the type of observations that can be performed to contribute to the study of the CSS/GPS sources. The last section provides guidelines on how to observe with the DSN antennas, and in particular at MDSCC. Title: Identifying the Rotation Rate and the Presence of Dynamic Weather on Extrasolar Earth-like Planets from Photometric Observations Authors: Pallé, E.; Ford, Eric B.; Seager, S.; Montañés-Rodríguez, P.; Vazquez, M. Bibcode: 2008ApJ...676.1319P Altcode: 2008arXiv0802.1836P With the recent discoveries of hundreds of extrasolar planets, the search for planets like Earth and life in the universe is quickly gaining momentum. In the future, large space observatories could directly detect the light scattered from rocky planets, but they would not be able to spatially resolve a planet's surface. Using reflectance models and real cloud data from satellite observations, here we show that, despite Earth's dynamic weather patterns, the light scattered by the Earth to a hypothetical distant observer as a function of time contains sufficient information to accurately measure Earth's rotation period. This is because ocean currents and continents result in relatively stable averaged global cloud patterns. The accuracy of these measurements will vary with the viewing geometry and other observational constraints. If the rotation period can be measured with accuracy, data spanning several months could be coherently combined to obtain spectroscopic information about individual regions of the planetary surface. Moreover, deviations from a periodic signal can be used to infer the presence of relatively short-lived structures in its atmosphere (i.e., clouds). This could provide a useful technique for recognizing exoplanets that have active weather systems, changing on a timescale comparable to their rotation. Such variability is likely to be related to the atmospheric temperature and pressure being near a phase transition and could support the possibility of liquid water on the planet's surface. Title: Cloudiness and Apparent Rotation Rate of Earth-like Planets Authors: Pallé, E.; Montañś-Rodríguez, P.; Vazquez, M.; Ford, E. B.; Seager, S. Bibcode: 2008ASPC..398..399P Altcode: If we were to observe the light reflected from an extrasolar planet, the portion of the planet reflecting starlight toward us would change due to rotation and orbital motion. Reflected light will come from the planet's surface, but also from the clouds and atmosphere. It is possible that these two planetary components have different rotation speeds, and the presence of clouds might result in so much variability that complicates efforts to determine its rotational period. Here we show how the differential rotation of the atmosphere/clouds is detectable even on Earth for certain observing geometries. Title: New Antenna Calibration Techniques in the Deep Space Network Authors: Rochblatt, D.; Richter, P.; Withington, P.; Vazquez, M.; Calvo, J. Bibcode: 2007IPNPR.169A...1R Altcode: This work describes the development of new automated antenna calibration instrumentation for the Deep Space Network (DSN). The purpose of the antenna calibration instrumentation is to provide reliable tools for the assessment, calibration, and improvement of the performance of the large number of antenna systems in the DSN, with special emphasis on Ka-band (32-GHz) performance of the 34-m beam-waveguide (BWG) antennas. The work describes the analysis that was done to characterize the various mechanisms that contribute to noise in the measurements. The results from the analysis led to design and development of a research and development calibration system that utilized the on-the-fly-mapping technique and was deployed at the DSN complex in Goldstone, California. Early results for calibration of the DSN ground antennas and the Cassini onboard radar as a radiometer are presented and agree well with analytical predictions. The system was further used in conjunction with a new fourth-order pointing model to achieve a record blind-pointing performance of the 34-m BWG antennas. The article concludes with a description of the design and implementation of an automated antenna calibration system based on these principles for the DSN: the Antenna Calibration and Measurement Equipment (ACME). Title: Human Exploration of Phobos and Deimos: Radioprotection Issues Authors: Vazquez, M. E. Bibcode: 2007epd..conf...40V Altcode: No abstract at ADS Title: Solar Rotation in the 17th century Authors: Casas, R.; Vaquero, J. M.; Vazquez, M. Bibcode: 2006SoPh..234..379C Altcode: Sunspot drawings made by Galileo Galilei in 1612 are used to derive the law of differential rotation at that time. The main interest of the work is during the time of observations, just at the beginning of telescopic observations and some decades before the Maunder Minimum (1645 - 1715), a period where the sunspots almost disappeared from the solar surface. For this purpose we have carried out careful corrections of the different sources of errors derived from the observing technique. By comparing with other results of the same century, a significant difference is only detected by comparing with data corresponding to the deep Maunder Minimum (Paris Observatory drawings). The characteristics of the solar differential rotation, and extrapolating the behavior of solar activity, did not differ before or after the Maunder Minimum. We also include an analysis of hitherto ignored sunspot drawings by N. Bion made in October and November 1672. Title: Neurotoxicity of human neural cells induced by space radiation: in vitro risk assessment and countermeasure Authors: Guida, P.; Vazquez, M.; Kim, A. Bibcode: 2006cosp...36..669G Altcode: 2006cosp.meet..669G As the duration of space missions increases the potential for neurological damage to astronauts resulting from exposure to radiation also increases To explore the cytotoxic effects of low and high LET radiation on cells of the central nervous system we utilized a model in vitro system consisting of a human neuronal progenitor cell line NT2 and its terminally differentiated derivative hNT neurons We found that exposure to numerous forms of ionizing radiation induced cell detachment necrosis and apoptosis in time dose and LET dependent manners From the slopes of the dose-response curves we calculated RBE values for each form of heavy ion radiation A sequential field of 1 GeV n protons and iron ions induced apoptosis to a greater extent than either ion alone and the time between hits was also an important determining factor In addition cycling neuronal progenitor cells underwent a dramatic G2 phase specific cell cycle delay within 6 hours following exposure to either low or high LET radiation The molecular effects of HZE radiation were also investigated with an emphasis on the cell stress response protein p53 Heavy ion radiation induced expression of p53 in a time and dose dependent manner in both neuronal progenitor and mature neuronal cells Furthermore several post-translational modifications to the p53 protein were detected 2 hours after exposure to gamma rays Experiments incorporating pifithrin- alpha a small molecule inhibitor of p53 suggest that induction of both apoptosis and the cell cycle delay in human NT2 cells is Title: Mice heterozygous for the ATM gene are more sensitive to both X-ray and heavy ion exposure than are wildtypes Authors: Worgul, B. V.; Smilenov, L.; Brenner, D. J.; Vazquez, M.; Hall, E. J. Bibcode: 2005AdSpR..35..254W Altcode: Previous studies have shown that the eyes of ATM heterozygous mice exposed to low-LET radiation (X-rays) are significantly more susceptible to the development of cataracts than are those of wildtype mice. The findings, as well as others, run counter to the assumption underpinning current radiation safety guidelines, that individuals are all equally sensitive to the biological effects of radiation. A question, highly relevant to human space activities is whether or not, in similar fashion there may exist a genetic predisposition to high-LET radiation damage. Mice haplodeficient for the ATM gene and wildtypes were exposed to 325 mGy of 1 GeV/amu 56Fe ions at the AGS facility of Brookhaven National Laboratory. The fluence was equivalent to 1 ion per lens epithelial cell nuclear area. Controls consisted of irradiated wildtype as well as unirradiated wildtype and heterozygous mice. Prevalence analyses for stage 0.5-3.0 cataracts indicated that not only cataract onset but also progression were accelerated in the mice haplo-deficient for the ATM gene. The data show that heterozygosity for the ATM gene predisposes the eye to the cataractogenic influence of heavy ions and suggest that ATM heterozygotes in the human population may also be radiosensitive. This may have to be considered in the selection of individuals who will be exposed to both HZE particles and low-LET radiation as they may be predisposed to increased late normal tissue damage. Title: Effects of Low Dose Particle Radiation to Mouse Neonatal Neurons in Culture Authors: Nojima, K.; Vazquez, M. E.; Okayasu, R.; Nagaoka, S. Bibcode: 2004cosp...35.2542N Altcode: 2004cosp.meet.2542N To investigate effects of low dose heavy particle radiation to CNS system, we adopted mouse neonatal brain cells in culture being exposed to heavy ions by HIMAC at NIRS and NSRL at BNL. The applied dose varied from 0.05Gy up to 2.0Gy. The subsequent biological effectswere evaluated by an induction of apoptosis and neuron survival focusing on the dependencies of the animal strains, SCID, B6, B6C3F1, C3H, used for brain cell culture, SCID was the most sensitive and C3H the least sensitive to particle radiation as evaluated by 10% apoptotic criterion. The LET dependency was compared with using SCID and B6 cells exposing to different ions (H, C, Ne, Si, Ar, and Fe). Although no detectable LET dependency was observed in the high LET (55 -200 keV/μ m) and low dose (<0.5 Gy) regions. The survivability profiles of the neurons were different in the mouse strains and ions. In this repot, a result of memory and learning function to adult mice after whole-body and brainlocal irradiation at carbon ion and iron ion. Title: The ALTEA/ALTEINO projects: studying functional effects of microgravity and cosmic radiation Authors: Narici, L.; Belli, F.; Bidoli, V.; Casolino, M.; De Pascale, M. P.; Di Fino, L.; Furano, G.; Modena, I.; Morselli, A.; Picozza, P.; Reali, E.; Rinaldi, A.; Ruggieri, D.; Sparvoli, R.; Zaconte, V.; Sannita, W. G.; Carozzo, S.; Licoccia, S.; Romagnoli, P.; Traversa, E.; Cotronei, V.; Vazquez, M.; Miller, J.; Salnitskii, V. P.; Shevchenko, O. I.; Petrov, V. P.; Trukhanov, K. A.; Galper, A.; Khodarovich, A.; Korotkov, M. G.; Popov, A.; Vavilov, N.; Avdeev, S.; Boezio, M.; Bonvicini, W.; Vacchi, A.; Zampa, N.; Mazzenga, G.; Ricci, M.; Spillantini, P.; Castellini, G.; Vittori, R.; Carlson, P.; Fuglesang, C.; Schardt, D. Bibcode: 2004AdSpR..33.1352N Altcode: The ALTEA project investigates the risks of functional brain damage induced by particle radiation in space. A modular facility (the ALTEA facility) is being implemented and will be operated in the International Space Station (ISS) to record electrophysiological and behavioral descriptors of brain function and to monitor their time dynamics and correlation with particles and space environment. The focus of the program will be on abnormal visual perceptions (often reported as "light flashes" by astronauts) and the impact on retinal and brain visual structures of particle in microgravity conditions. The facility will be made available to the international scientific community for human neurophysiological, electrophysiological and psychophysics experiments, studies on particle fluxes, and dosimetry. A precursor of ALTEA (the `Alteino' project) helps set the experimental baseline for the ALTEA experiments, while providing novel information on the radiation environment onboard the ISS and on the brain electrophysiology of the astronauts during orbital flights. Alteino was flown to the ISS on the Soyuz TM34 as part of mission Marco Polo. Controlled ground experiments using mice and accelerator beams complete the experimental strategy of ALTEA. We present here the status of progress of the ALTEA project and preliminary results of the Alteino study on brain dynamics, particle fluxes and abnormal visual perceptions. Title: Animal imaging studies of potential brain damage Authors: Gatley, S. J.; Vazquez, M. E.; Rice, O. Bibcode: 2004cosp...35.3060G Altcode: 2004cosp.meet.3060G To date, animal studies have not been able to predict the likelihood of problems in human neurological health due to HZE particle exposure during space missions outside the Earth's magnetosphere. In ongoing studies in mice, we have demonstrated that cocaine stimulated locomotor activity is reduced by a moderate dose (120 cGy) of 1 GeV 56Fe particles. We postulate that imaging experiments in animals may provide more sensitive and earlier indicators of damage due to HZE particles than behavioral tests. Since the small size of the mouse brain is not well suited to the spatial resolution offered by microPET, we are now repeating some of our studies in a rat model. We anticipate that this will enable us to identify imaging correlates of behavioral endpoints. A specific hypothesis of our studies is that changes in the metabolic rate for glucose in striatum of animals will be correlated with alterations in locomotor activity. We will also evaluate whether the neuroprotective drug L-deprenyl reduces the effect of radiation on locomotor activity. In addition, we will conduct microPET studies of brain monoamine oxidase A and monoamine oxidase B in rats before and at various times after irradiation with HZE particles. The hypothesis is that monoamine oxidase A, which is located in nerve terminals, will be unchanged or decreased after irradiation, while monoamine oxidase B, which is located in glial cells, will be increased after irradiation. Neurochemical effects that could be measured using PET could in principle be applied in astronauts, in terms of detecting and monitoring subtle neurological damage that might have occurred during long space missions. More speculative uses of PET are in screening candidates for prolonged space missions (for example, for adequate reserve in critical brain circuits) and in optimizing medications to treat impairments after missions. Title: Effects of heavy ions on visual function and electrophysiology of rodents: the ALTEA-MICE project Authors: Sannita, W. G.; Acquaviva, M.; Ball, S. L.; Belli, F.; Bisti, S.; Bidoli, V.; Carozzo, S.; Casolino, M.; Cucinotta, F.; De Pascale, M. P.; Di Fino, L.; Di Marco, S.; Maccarone, R.; Martello, C.; Miller, J.; Narici, L.; Peachey, N. S.; Picozza, P.; Rinaldi, A.; Ruggieri, D.; Saturno, M.; Schardt, D.; Vazquez, M. Bibcode: 2004AdSpR..33.1347S Altcode: ALTEA-MICE will supplement the ALTEA project on astronauts and provide information on the functional visual impairment possibly induced by heavy ions during prolonged operations in microgravity. Goals of ALTEA-MICE are: (1) to investigate the effects of heavy ions on the visual system of normal and mutant mice with retinal defects; (2) to define reliable experimental conditions for space research; and (3) to develop animal models to study the physiological consequences of space travels on humans. Remotely controlled mouse setup, applied electrophysiological recording methods, remote particle monitoring, and experimental procedures were developed and tested. The project has proved feasible under laboratory-controlled conditions comparable in important aspects to those of astronauts' exposure to particle in space. Experiments are performed at the Brookhaven National Laboratories [BNL] (Upton, NY, USA) and the Gesellschaft für Schwerionenforschung mbH [GSI]/Biophysik (Darmstadt, FRG) to identify possible electrophysiological changes and/or activation of protective mechanisms in response to pulsed radiation. Offline data analyses are in progress and observations are still anecdotal. Electrophysiological changes after pulsed radiation are within the limits of spontaneous variability under anesthesia, with only indirect evidence of possible retinal/cortical responses. Immunostaining showed changes (e.g increased expression of FGF2 protein in the outer nuclear layer) suggesting a retinal stress reaction to high-energy particles of potential relevance in space. Title: Mice heterozygous for the ATM gene are more sensitive to heavy ions exposure than are wildtypes Authors: Worgul, B.; Smilenov, L.; Brenner, D.; Vazquez, M.; Hall, E. Bibcode: 2004cosp...35.4027W Altcode: 2004cosp.meet.4027W Previous studies have shown that the eyes of atm heterozygous mice exposed to Low LET radiation (X-rays) are more susceptible to the development of cataracts than are those of wildtype mice. The findings, as well as others, run counter to the assumption underpinning current radiation safety guidelines, that individuals are all equally sensitive to the biological effects of radiation. A question, highly relevant to human space activities is whether or not, in similar fashion there may exist a genetic predisposition to High LET radiation damage. Again the lens and, its primary radiopathy, cataract, were used to assay for the effects of ATM deficiency in a late-responding tissue. Together with those of wildtypes, the eyes of AT heterozygous knockout mice were exposed to 325 mGy of 1 GEV/amu 56Fe ions at the AGS facility of Brookhaven National Laboratory. The fluence was equivalent to 1 ion per nuclear area. As was the case in the earlier X-ray studies all irradiations were done on the 28th day after birth. Controls consisted of wildtype irradiated as well as unirradiated wildtype and heterozygotes. Ten mice from each group were examined weekly by conventional slitlamp biomicroscopy for a total of 35 weeks. The time required for prevalence to reach 50% (T50) as an endpoint for each stage indicated that not only cataract onset but also progression were accelerated in the mice haplo-deficient for the atm gene. For example the T50 for definitive cataract onset (stage 1) in the atm heterozygotes was 10 weeks whereas 17 weeks were required for the wildtypes. Similarly at the conclusion of the experiment (35 weeks), 40% of the lenses of allele-deficient mice had progressed to stage 3 (near fully opaque and obviously visually debilitating), while only one lens (5%) from the wildtype irradiated eyes achieved that stage. The data show that heterozygosity for the atm gene predisposes the eye to the cataractogenic influence of heavy ions and suggest that AT heterozygotes in the human population may also be radiosensitive. This may have to be considered in the selection of individuals who will be exposed to both HZE particles and Low-LET radiation as they may be predisposed to increased late normal tissue damage. Supported by NASA Grant NAG 9-1148 and Research to Prevent Blindness, Inc. Title: Effect of 1 GeV/n Fe particles on cocaine-stimulated locomotor activity Authors: Vazquez, M.; Bruneus, M.; Gatley, J.; Russell, S.; Billups, A. Bibcode: 2004cosp...35.3082V Altcode: 2004cosp.meet.3082V Space travel beyond the Earth's protective magnetic field (for example, to Mars) will involve exposure of astronauts to irradiation by high-energy nuclei such as 56Fe (HZE radiation), which are a component of galactic cosmic rays. These particles have high linear energy transfer (LET) and are expected to irreversibly damage cells they traverse. Our working hypothesis is that long-term behavioral alterations are induced after exposure of the brain to 1 GeV/n iron particles with fluences of 1 to 8 particles/cell targets. Previous studies support this notion but are not definitive, especially with regard to long-term effects. Using the Alternating Gradient Synchrotron (AGS) we expose C57 mice to 1 GeV/n 56Fe radiation (head only) at doses of 0, 15, 30, 60, 120 and 240 cGy. There were originally 19 mice per group. The ability of cocaine to increase locomotor activity in 16 of these animals in response to an intraperitoneal injection of cocaine has been measured so far at 1, 4, 8, 12, 16, 20, 24 and 28 weeks. Cocaine-stimulated locomotor activity was chosen in part because it is a behavioral assay with which we have considerable experience. More importantly, the ability to respond to cocaine is a complex behavior involving many neurotransmitter systems and brain circuits. Therefore, the probability of alteration of this behavior by HZE particles was considered high. However, the central circuit is the nigrostriatal dopamine system, in which dopamine is released in striatum from nerve terminals whose cell bodies are located in the substantia nigra. Cocaine activates behavior by blocking dopamine transporters on striatal nerve terminals and therefore elevating the concentration of dopamine in the synapse. Dopamine activates receptors on striatal GABAergic cells that project via other brain regions to the thalamus. Activation of the motor cortex by glutamatergic projections from the thalamus leads ultimately to increased locomotion. The experimental paradigm involves placing mice in a plexiglass box fitted with arrays of photocells. A mouse placed in the box exhibits exploratory behavior that diminishes to a low level over the course of about 20 min. Iron particle irradiation caused dose related reductions in locomotor activity stimulated by cocaine, as evidenced by the group data presented here. The impairments after HZE radiation appeared to be persistent. Irradiation using a 137Co source also led to alterations in cocaine-stimulated locomotion at early times, but, unlike the situation for HZE radiation, these disappeared at later times. These studies were very recently terminated and data analysis is not yet complete. For example, spontaneous activity was also monitored, and it is possible that comparison of stimulated and spontaneous locomotion for each animal may expose larger changes. Most of the mice were sacrificed and their brains stored for histology and neurochemistry. Ex vivo determination of dopamine transporter status in striata of some of the mice indicated no large decrease in this marker of pre-synaptic dopamine terminals, supporting an earlier pilot study in rats. Title: Cellular and molecular effects of high-LET radiation on human neural stem cells and neurons Authors: Vazquez, M.; Guida, P.; Green, L.; Chang, P.; Otto, S. Bibcode: 2004cosp...35.3061V Altcode: 2004cosp.meet.3061V Because successful operations in space depend in part on the performance capabilities of astronauts, radiation-induced neurological damage could jeopardize the successful completion of mission requirements, as well as have long-term consequences on the health of astronauts. As such, understanding the nature of this risk may be vital to the effective performance of astronauts during future missions in space. This paper describes the neural cell responses to conventional and charged particles radiation in cell culture systems. One of the goals is to characterize radiation-induced neural cell damage pathways; especially those related to apoptosis induction and its modification by pharmacological manipulation. Our laboratory utilizes the method of flow cytometry to measure the induction of apoptosis and necrosis in cells. Neural stem cells (NT2) were exposed to the different ions; we measured a dose-dependent induction of apoptosis. NT2 cells were exposed to graded doses of 1 and 5 GeV/n Fe, 0.29 GeV/n C, 1 GeV/n Ti, and 0.6 GeV/n Si ions and samples were taken at 48 hours after exposure. The percentage of apoptotic cells in culture was measured by FITC-Annexin V by flow cytometry. Similar data obtained from NT2 cells exposed to 255 MeV/n protons and 137Cs are included for comparison. Preliminary RBE calculations demonstrated that iron ions are more effective in inducing apoptosis. Exposure of cells to ionizing radiation produces changes in the expression of many genes as cells react to this insult. At present, the identities of the molecular changes that occur in response to HZE radiation remain largely unknown. In an effort to reveal this information, we screened an array (Superarray) of p53-related genes with RNA purified from NT2 cells mock irradiated or exposed to 50 cGy of 1 GeV/n iron ions. Preliminary results indicated that the expression of numerous critical genes was altered 3 hours after HZE radiation exposure. By performing Western blot analysis on NT2 cells exposed to 5 GeV/n iron ions, we demonstrated a time and dose dependent increase in p53 protein levels. This induction occurred as early as 6 hours post-irradiation, and was detectable with a dose as low as 10 cGy. Meanwhile, the levels of the structural protein actin did not change in these cell samples, assuring accurate protein quantization and equal loading from sample to sample. We have also shown a time and dose dependent increase in p53 protein levels in terminally differentiated human neuronal (hNT) cells exposed to 1 GeV/n iron ions. Using a more detailed protocol of early harvesting times, we determined that p53 accumulated in these neuronal cells within 8 hours after irradiation. Our laboratory's demonstration that HZE radiation exposure results in a dose dependent induction of p53 protein, concomitant with our finding of a dose dependent induction of apoptosis in the neural stem (NT2) cells, strongly implies that p53 plays a major role in this HZE radiation-induced apoptosis response. Title: Detection of microlesions induced by heavy ions using liposomes filled with fluorescent dye Authors: Koniarek, J. P.; Thomas, J. L.; Vazquez, M. Bibcode: 2004AdSpR..34.1373K Altcode: In cells irradiation by heavy ions has been hypothesized to produce microlesions, regions of local damage. In cell membranes this damage is thought to manifest itself in the form of holes. The primary evidence for microlesions comes from morphological studies of cell membranes, but this evidence is still controversial, especially since holes also have been observed in membranes of normal, nonirradiated, cells. However, it is possible that damage not associated with histologically discernable disruptions may still occur. In order to resolve this issue, we developed a system for detecting microlesions based on liposomes filled with fluorescent dye. We hypothesized that if microlesions form in these liposomes as the result of irradiation, then the entrapped dye will leak out into the surrounding medium in a measurable way. Polypropylene vials containing suspensions of vesicles composed of either dipalmitoyl phosphatidylcholine, or a combination of egg phosphatidylcholine and cholesterol were irradiated at the Brookhaven National Laboratory using 56Fe ions at 1 GeV/amu. In several cases we obtained a significant loss of the entrapped dye above the background level. Our results suggest that holes may form in liposomes as the result of heavy ion irradiation, and that these holes are large enough to allow leakage of cell internal contents that are at least as large as a 1 nm diameter calcein molecule. Title: Transmediterranean flights,in the edge of two centuries. Authors: Cosentino, O.; Caballero, F.; Ibba, R.; Gerardi, G.; Cecchini, G.; Fernandez Abad, A.; Vazquez, M. Bibcode: 2002cosp...34E.378C Altcode: 2002cosp.meetE.378C Transmediterranean flights program goal is to perform stratospheric balloons flights carrying scientific/technological payloads at 40 Km altitude and approximate 38°N latitude.ASI and INTA continued the early ASI-CNES-INTA program with several stratospheric flights since 1993.The network comprises three stations located at Trapani-Milo (Italy),Palma de Mallorca and El Arenosillo(Spain). Nine successful transmediterranean crossings were performed in this program stage. Four new transmediterranean flights are scheduled for summer 2002 .These include astronomical,biological and technological experiments .Beside , three local flights will be performed at Trapani-Milo next summer. Technical tracking that encompasses telemetry,telecommand and localization uses allocated UHF band,in the old classical and the new Mini Telemetry configurations. Flight qualification of a S-band TM/TC equipment was realised ,using local flights, in 1997 and 1998.In summer 2002,a S band flight will be realised over the Mediterranean with the UHF telemetry as a backup. A summary of system requirements , that would assure state-of-the-art open stratospheric balloons flights is presented . When flying over the Iberian Peninsula , the time of land overflight diminishes , in direct relationship , with the balloon drift toward the South.A latitude control , applied in our case , should enhance the flight feasibility. Trajectory predictions,must incorporate radiosoundings of more places,to take into account several possibilities of descent.Also El Arenosillo soundings ,usually three days a week,should be increased ,in order to validate the new atmospheric models. Beside altitude control handled mainly by the ballast , in the future "boomerang" flights of a transmediterranean scale,opening/closing of the valves will be used. Active floating system,comb ined with waterproof electronic and experiment boxes and a minimal time of arrival to the gondola , become critical points in case of an unplanned overwater descent for recovery.With regard to power storage subsystems Ni-H2,NiMH and Li-ion batteries,should be embarked onboard new flights to gain experiences,acting in this way,as in others,as a technological testbed of industry designs. Thermal control subsystems,should withstand the cycle sunrise-sunset-sunrise,if the usual 1 day flights are to be extended 10 hours , under the "boomerang" principle.In summer 2002 , a High Performance Gondola experiment will carry an azimuthal stabilization system using GPS phase variation.Parachutes employed were either in- dividual or a bunch of three,in the ASI-CNES-INTA program stage. A payload precision descent,involving GPS to aim at a preselected descent point,will help to reduce the risk index over land zones. Title: Effects of high-LET radiation on neural cells in culture: apoptosis induction, cell toxicity and gene expression Authors: Vazquez, M.; Otto, S.; Estevez, L.; Rios, D.; Pena, L.; Anderson, C. Bibcode: 2002cosp...34E2299V Altcode: 2002cosp.meetE2299V Despite the fact that some in vivo studies suggest that chronic low-dose exposure to HZE particles might produce effects similar to aging and neurodegeneration, the basic mechanisms of HZE particle neurotoxicity remain to be elucidated. The goal of these experiments is to establish neural cellular models to evaluate the capacity of low- and high-LET radiation, to induce cell damage and apoptosis. In the present study we measured apoptosis, cell toxicity and gene expression induced by low fluences-doses of heavy ions, protons and photons using neuronal precursor cells (NT2, STRATAGENE) and post-mitotic neurons as models for adult neural cell system. Using heavy ions accelerated at AGS (BNL) and HIMAC (Chiba, Japan), and protons (Loma Linda) we study the neurotoxic effects of a variety of heavy particles (1 and 0.6 GeV/n Fe, 580 MeV/n Si, 290 MeV/n C, 550 MeV/n Ar; LET ranging from 13 to148 keV/μm), and 255 MeV/n protons. Apoptosis Induction: We measured the induction of apoptosis by flow cytometry using a FACSCalibur to detect the expression of Annexin V, as an early marker in the apoptotic pathway, in NT-2 cells. The ApoAlert Annexin V assay is based on the observation that soon after initiating apoptosis, most cell types translocate phosphatidylserine (PS) from the inner face of the plasma membrane to the cell surface. Once on the cell surface, PS can be easily detected by staining with a FITC conjugate of Annexin V, a protein that has a strong natural affinity for PS. Externalization of PS occurs earlier than the nuclear changes associated with apoptosis, so the ApoAlert Assay detects apoptotic cells significantly earlier than do DNA-based assays. Exposing NT-2 cells to Fe ions and protons induced a strong dose- and time-dependent induction of apoptosis with the peak of apoptosis appearing at 72 hours post-irradiation. It was determined that Fe ion exposure were more effective to induce apoptosis in comparison to protons and gamma rays, suggesting an high RBE values for apoptosis in exposed NT2 cells at 72 hr post-irradiation. Cell Toxicity: Cell damage at different time points after exposure to charge particle radiation was determined by using the Live/Dead Viability/Cytotoxicity Kit on attached cells from 4 well plates. The LIVE/DEAD Kit provides a two-color fluorescence-based cell viability assay that allows the simultaneous determination of live and dead cells. Results obtained from BNL-7 indicated a dose- and time dependent increase of cell damage. Doses as low as 0.1 Gy were able to induce a significant increase of cell damage in comparison to controls. Colorimetric (XTT) assays and the evaluation of the number of attached and floating cells confirmed this trend. Gene Expression: Conventional western blot techniques were employed to monitor p53 and WAF-p21 gene expression. A subset of NT2 cell samples were lysed at different time points for the determination of p53 and WAFp21 expression using monoclonal antibodies against human p53 and p21. In BNL-7 we observed that p53 is over-expressed as a function of dose of particle exposure and time post-exposure. Doses as low as 0.25 Gy were able to up- regulate p53 and as early as 24 hours post-exposure. Doses of 0.75 Gy were able to up-regulate p53 as early as 12 hours post-exposure. Similar results were obtained when NT-2 cells were exposed to gamma or proton exposures, although higher doses were required to obtain similar degree of expression. These results appear to confirm that p53 gene is involved in the stress pathway induced by low- and high- LET radiation exposures. Up to this point we were not able to confirm changes in the expression of WAFp21 after radiation exposure in NT2 cells. Title: Behavioral effects of heavy ions and protons and potential countermeasure agents Authors: Vazquez, M.; Gatley, J.; Bruneus, M.; Koslosky, S.; Billups, A. Bibcode: 2002cosp...34E2300V Altcode: 2002cosp.meetE2300V Space travel beyond the Earth's protective magnetic field (for example, to Mars) will involve exposure of astronauts to irradiation by high-energy nuclei such as 56 Fe, which are a component of galactic cosmic rays. These particles have high linear energy transfer (LET) and are expected to irreversibly damage cells they traverse. Exposure to HZE radiation may therefore cause progressive deterioration of brain function, adding to other inescapable damage involved in normal aging. We propose a study of the hypothesis that long-term behavioral alterations are induced after exposure of the brain to 1 GeV/n iron and silicon particles with fluences of 1 to 8 particles/cell targets. Previous studies support this notion but are not definitive, especially with regard to long-term effects. Our principal goal is to examine the neurological effects of high-LET radiation on C57BL/6 mice using a series of behavioral tests to unveil the temporal expression of altered behaviors in the radiation response, as well as the means, which can modulate these responses. The studies planned in this project are designed to: 1) Characterize the behavioral consequences after exposure to low-fluences of heavy ions and protons on C57BL/6 mice. The main behavioral endpoints to be used in these studies are locomotor activity to evaluate the integrity of striatal dopaminergic pathways, and spatial reference memory to probe hippocampal cholinergic pathways. 2) Characterize the neurochemical and structural changes induced by heavy ions and protons. 3) To develop countermeasures to protect neural cell populations exposed to low fluences of heavy ions and protons. The project will test methods to protect injured neural cells based on their molecular and cellular mechanisms that may regulate neural cell survival in the central nervous system. Among the methods that will be studied is the direct administration of neuroprotective molecules as well as the modulation of apoptotic pathways by pharmacological manipulation. The effects of 3 different neuro/radioprotectors (GM1, melatonin and PTF-) on the levels of radiation induced neurochemical and structural damage will be compared with the level of behavioral alterations to determine a cause/effect relationship Title: Earthshine: A Proposal To Build An Automatic System For Observing Terrestrial Albedo. Authors: Thejll, P.; Ulla, A.; Hanslmeier, A.; Chou, D. -Y.; Goode, P.; Vazquez, M.; Belmonte, J. A. Bibcode: 2002EGSGA..27.4058T Altcode: Terrestrial albedo data are important for climate model studies because of the impor- tance albedo has on the net radiation budget of the Earth. Direct measurements of the albedo are not common, and there is no dataset with global coverage that offers an alternative to data from satellite measurements. The satellite data, however, are often from weather satellites that were not specifically designed to guarantee long-term sen- sitivity stability in the imaging data, and thus in the albedo data that can be derived from these. Therefore, absolute calibration of terrestrial satellite albedo data is not possible.

The Earth reflects light onto the Moon proportional to the albedo, and it is possible to measure from the Earth the so called 'earthshine' on the Moon, so accurately that a cost-effective system for mean-terrestrial albedo monitoring can be built on the basis of small robotic telescopes. We present a system for observation and data-handling, that could provide data for albedo studies. The system is intrinsically stable and would be able to produce data of long-term stability so that questions related to the drift in satellite data could be investigated in the future. Title: Fluorescein dye filled vesicles as models for detection of microlesions Authors: Koniarek, J.; Thomas, J.; Vazquez, M. Bibcode: 2002cosp...34E2659K Altcode: 2002cosp.meetE2659K The primary evidence for microlesions in cell membranes caused by heavy ions is from morphological studies. This evidence, however, could not be corroborated. That said, it is possible to envision functional damage not associated with histologically discernable disruption. In order to resolve this issue experimental evidence is needed using a model that can produce reliable and unequivocal results. We developed a model system for detecting microlesions based on cell membrane mimics made of spherical vesicles 0.1 μm in diameter formed by molecules prepared from phosphatidylcholine and cholesterol. These vesicles contain the fluorescent dye calcein. We hypothesize that if microlesions form in these vesicles then upon irradiation the fluorescent dye will leak out into the surrounding medium in a measurable way. Vials containing these vesicles were irradiated at the Brookhaven National Laboratory. In one instance irradiation by 1 GeV 56Fe ions produced a significant loss of the entrapped fluorescent dye, 15 % above the background level. However, a replicate irradiation produced no leakage above the background level. Despite these initial inconclusive results we believe that the dye-filled vesicle model still has potential to clarify the microlesion hypothesis. However additional experiments are needed to validate this model in view of the contradictory results obtained in our initial experiments. Title: Cosmic Ray Hits in the Central Nervous System at Solar Maximum Authors: Curtis, S. B.; Vazquez, M. E.; Wilson, J. W.; Atwell, W.; Kim, M. -H. Y. Bibcode: 2000AdSpR..25.2035C Altcode: It has been suggested that a manned mission to Mars be launched at solar maximum rather than at solar minimum to minimize the radiation exposure to galactic cosmic rays. It is true that the number of hits from highly ionizing particles to critical regions in the brain will be less at solar maximum, and it is of interest to estimate how much less. We present here calculations for several sites within the brain from iron ions (z = 26) and from particles with charge, z, greater than or equal to 15. The same shielding configurations and sites in the brain used in an earlier paper for solar minimum are employed so that direct comparison of results between the two solar activity conditions can be made. A simple pressure-vessel wall and an equipment room onboard a spacecraft are chosen as shielding examples. In the equipment room, typical results for the thalamus are that the probability of any particles with z greater than or equal to 15 and from 2.3 percent to 1.3 percent for iron ions. The extra shielding provided in the equipment room makes little difference in these numbers. We conclude that this decrease in hit frequency (less than a factor of two) does not provide a compelling reason to avoid solar minimum for a manned mission to Mars. This conclusion could be revised, however, if a very small number of hits is found to cause critical malfunction within the brain Title: Long-Term Observations of Solar Active Regions at the VNT Authors: Bonet, J. A.; Casas, R.; Giammanco, C.; Martinez Pillet, V.; Vazquez Bibcode: 2000ESASP.463..635B Altcode: 2000sctc.proc..635B No abstract at ADS Title: In Vitro Neurotoxic Effects of 1 GeV/n Iron Particles Assessed in Retinal Explants Authors: Vazquez, M. E.; Kirk, E. Bibcode: 2000AdSpR..25.2041V Altcode: The heavy ion component of the cosmic radiation remains problematic to the assessment of risk in manned space flight. The biological effectiveness of HZE particles has yet to be established, particularly with regard to nervous tissue. Using heavy ions accelerated at the AGS of Brookhaven National Laboratory, we study the neurotoxic effects of iron particles. We exposed retinal explants, taken from chick embryos, to determine the dose response relationships for neurite outgrowth. Morphometric techniques were used to evaluate the in vitro effects of 1 GeV/a iron particles (LET 148 keV/μm). Iron particles produced a dose-dependent reduction of neurite outgrowth with a maximal effect achieved with a dose of 100 cGy. Doses as low as 10-50 cGy were able to induce reductions of the neurite outgrowth as compared to the control group. Neurite generation is a more sensitive parameter than neurite elongation, suggesting different mechanism of radiation damage in our model. These results showed that low doses/fluences of iron particles could impair the retinal ganglion cells' capacity to generate neurites indicating the highly neurotoxic capability of this heavy charged particle Title: Neurobiological problems in long-term deep space flights Authors: Vazquez, M. E. Bibcode: 1998AdSpR..22..171V Altcode: Future missions in space may involve long-term travel beyond the magnetic field of the Earth, subjecting astronauts to radiation hazards posed by solar flares and galactic cosmic rays, altered gravitation fields and physiological stress. Thus, it is critical to determine if there will be any reversible or irreversible, detrimental neurological effects from this prolonged exposure to space. A question of particular importance focuses on the long-term effects of the space environment on the central nervous system (CNS) neuroplasticity, with the potential acute and/or delayed effects that such perturbations might entail. Although the short-term effects of microgravity on neural control were studied on previous low earth orbit missions, the late consequences of stress in space, microgravity and space radiation have not been addressed sufficiently at the molecular, cellular and tissue levels. The possibility that space flight factors can interact influencing the neuroplastic response in the CNS looms critical issue not only to understand the ontogeny of the CNS and its functional integrity, but also, ultimately the performance of astronauts in extended space forays. The purpose of this paper is to review the neurobiological modifications that occur in the CNS exposed to the space environment, and its potential consequences for extended deep space flight. Title: Cosmic ray hit frequencies in critical sites in the central nervous system Authors: Curtis, S. B.; Vazquez, M. E.; Wilson, J. W.; Atwell, W.; Kim, M.; Capala, J. Bibcode: 1998AdSpR..22..197C Altcode: One outstanding question to be addressed in assessing the risk of exposure to space travelers from galactic cosmic rays (GCR) outside the geomagnetosphere is to ascertain the effects of single heavy-ion hits on cells in critical regions of the central nervous system (CNS). As a first step toward this end, it is important to determine how many ``hits'' might be received by a neural cell in several critical CNS areas during an extended mission outside the confines of the earth's magnetic field. Critical sites in the CNS: the macula, and an interior brain point (typical of the genu, thalamus, hippocampus and nucleus basalis of Meynert) were chosen for the calculation of hit frequencies from galactic cosmic rays for a mission to Mars during solar minimum (i.e., at maximum cosmic-ray intensity). The shielding at a given position inside the body was obtained using the Computerized Anatomical Man (CAM) model, and a radiation transport code which includes nuclear fragmentation was used to calculate yearly fluences at the point of interest. Since the final Mars spacecraft shielding configuration has not yet been determined, we considered the minimum amount of aluminum required for pressure vessel-wall requirements in the living quarters of a spacecraft, and a typical duty area as a pressure vessel plus necessary equipment. The conclusions are: (1) variation of the position of the ``target site'' within the head plays only a small role in varying hit frequencies; (2) the average number of hits depends linearly on the cross section of the critical portion of the cell assumed in the calculation; (3) for a three-year mission to Mars at solar minimum (i.e., assuming the 1977 spectrum of galactic cosmic rays), 2% or 13% of the ``critical sites'' of cells in the CNS would be directly hit at least once by iron ions, depending on whether 60 mum^2 or 471 mum^2 is assumed as the critical cross sectional area; and (4) roughly 6 million out of some 43 million hippocampal cells and 55 thousand out of 1.8 million thalamus cell nuclei would be directly hit by iron ions at least once on such a mission for space travelers inside a simple pressure vessel. Also, roughly 20 million out of 43 million hippocampal cells and 230 thousand out of 1.8 million thalamus cell nuclei would be directly hit by one or more particles with z >= 15 on such a mission. Title: Preface Authors: Vazquez, M. E. Bibcode: 1998AdSpR..22..169V Altcode: No abstract at ADS Title: The IAC's Near Infrared Camera Authors: Collados, M.; Joven, E.; Fuentes, F. J.; Diaz, J. J.; Gonzalez Escalera, V.; Bonet, J. A.; Vazquez, M. Bibcode: 1997ASPC..118..361C Altcode: 1997fasp.conf..361C Here we report the main characteristics of the recently acquired near infrared camera. It is based on a 256x256 HgCdTe Nicmos-3 array, sensitive from 1 mu m to 2.5mu m. The pixel size is 40mu mx40mu m, adequate for the spatial and spectral scales at the different telescopes operating at the observatories of La Palma and Tenerife. The cooling system operates with LN2 with a hold time larger than 20 hours. The camera will be used for photometric, spectroscopic and spectropolarimetric observations. Title: 1st Advances in Solar Physics Euroconference: Advances in the Physics of Sunspots Authors: Schmieder, B.; del Toro Iniesta, J. C.; Vazquez, M. Bibcode: 1997ASPC..118.....S Altcode: 1997fasp.conf.....S No abstract at ADS Title: Spatial changes of the oscillatory pattern in sunspot penumbrae at the photospheric level. Authors: Marco, E.; Aballe Villero, M. A.; Vazquez, M.; Garcia de La Rosa, J. I. Bibcode: 1996A&A...309..284M Altcode: We analyze time sequences of photospheric spectral lines in the penumbra of two sunspots. Two spectral lines sensitive to velocity fluctuations at two different heights in the atmosphere (Ti I 8396.9A and Fe II 7224.5A) are used. The observations were taken using the Gregory-Coude Telescope (GCT) at the Observatorio del Teide (Tenerife). Velocity fluctuations were determined by measuring the shifts of the line cores. The oscillatory power was calculated at three frequency bands: low frequency (1.5-2.5mHz), and five (2.8-3.8mHz) and three minute bands (5.1-6.1mHz). The main results are: -For the first time penumbral oscillations are clearly detected in the deep layers of the photosphere (Fe II line). -Significant variations are found between the inner, medium and outer parts of the penumbra. Based on a geometrical model for the average inclination of the magnetic field lines and assuming that these are co-spatial with the filaments, we conclude that for the lower photospheric layers (Fe II line) the velocity perturbations, at the inner and middle penumbra, are aligned with magnetic field lines. This is clearly not the case for the outer penumbra. However, the Ti line, formed in the upper layers, exhibits a more irregular behaviour. Hence, the oscillatory behaviour of the penumbral upper layers does not seem to be related to the filamentary topology visible in the continuum. Title: Numerical modelling of spectral line asymmetries in photospheric structures. II. Plage regions. Authors: Marquez, I.; Bonet, J. A.; Vazquez, M. Bibcode: 1996A&A...306..305M Altcode: A numerical code has been developed for modelling the asymmetries in three spectral lines (K I 7699, Fe I 5576 and Fe I 5635A) formed at different photospheric heights and observed in plage regions near the solar disk center. The aim of this work was to reproduce the absolute line bisectors obtained from low resolution observations. The mere insertion of a flux tube in a model of quiet granulation, without mutual interaction, has proved insufficient to explain many of the observational results. Therefore, several models of abnormal granulation close to the tube, representing the influence of the magnetic field, are considered. The code consists of two computation modules, one representing a model of the unperturbed photosphere, and the other including a flux tube inserted in a model of altered granulation; various combinations of both computation modules allow different values of the magnetic filling factor to be simulated. The influence of other physical parameters and observational aspects on the bisector is also discussed, e.g. waves, microturbulence, defective time or spatial averages, etc. The proposed model reproduces the observed variation in the shape and in the absolute shift of the bisector when the filling factor increases. Likewise, the computed spatial distribution of intensity in the continuum fits many of the photometric results reported in the literature for plage regions. Title: Numerical modelling of spectral line asymmetries in photospheric structures. I. Quiet Sun. Authors: Marquez, I.; Bonet, J. A.; Vazquez, M.; Woehl, H. Bibcode: 1996A&A...305..316M Altcode: Modelling of asymmetries in spectral lines with different formation heights (K I 7699, Fe I 5576 and Fe I 5635A), observed in the quiet Sun at the disk center, has been performed with the aim of reproducing the absolute line bisectors obtained from low resolution observations. The influence of a number of physical and observational factors on the bisector shape and line shifts, acting together or separately, is discussed, e.g. mesogranular flows, waves, microturbulence, defective temporal and spatial averages, etc. The simulations are based on the VAL-C model (Vernazza et al. 1981) representing the mean photosphere, and the granular model by Nelson (1978). Following evidence in the literature, the best match to the observed absolute mean bisectors is obtained by including in the numerical code a gravity wave and a strengthening of the microturbulence in the lower layers of the intergranule. Title: Book-Review : New Windows to the Universe vol. 1 and 2 Authors: Sanchez, R.; Vazquez, M.; Andrews, A. D. Bibcode: 1996IrAJ...23Q.127S Altcode: No abstract at ADS Title: Optic systems with spherical, cylindrical, and toric surfaces Authors: Barcala, J.; Vazquez, M. C.; Garcia, A. Bibcode: 1995ApOpt..34.4900B Altcode: A simple analytical method for tracing rays in an optical system that is made up of spherical, cylindrical, and toric surfaces with an arbitrary rotation of its meridian plane with respect to the reference system is described. An analytical procedure is also given for obtaining the spot diagram on an arbitrarily oriented section, as well as for relating the diagram obtained for the plane of this section as a plane z = 0. Finally, as an application of this procedure, several graphic representations of the spot diagrams in the planes perpendicular or nonperpendicular to the axis are presented. Title: Photometry of sunspot pores from partial eclipse observations. Authors: Bonet, J. A.; Sobotka, M.; Vazquez, M. Bibcode: 1995A&A...296..241B Altcode: White-light images, centered at λ6708A, were obtained at the Swedish Solar Telescope, La Palma, on occasion of the 1994 May 10 partial solar eclipse. From the recorded information, 5 frames showing several pores together with the moon's limb were selected for detailed photometric analysis. The observed intensity profile of the moon's limb projected against the solar disk was used to derive, from each frame, the Point Spread Function of the atmosphere + instrument to restore the images. The characteristics of the obtained PSFs -low noise and precise determination of the wings far away from the core- enabled us to avoid arbitrary assumptions about analytical approximations. The FWHM of these functions was typically 0.47". Several bright features were identified in one of the pores. After determining the photometric parameters of these fine umbral structures their link with the population of the bright features in the umbra of evolved spots is discussed in the framework of the dependence of sunspot properties on the spot size. Title: Observed differences between large and small sunspots. Authors: Collados, M.; Martinez Pillet, V.; Ruiz Cobo, B.; del Toro Iniesta, J. C.; Vazquez, M. Bibcode: 1994A&A...291..622C Altcode: We confirm recent results about the differences in temperature and magnetic field strength between the umbra of large and small sunspots. Five Stokes I- and V-spectra from the darkest cores of three different umbrae have been analysed with the inversion code of the radiative transfer equation by Ruiz Cobo & del Toro Iniesta (1992). The run with depth of temperature, magnetic field (strength and inclination) and velocity along the line of sight are obtained. The larger sunspots turn out to be cooler and possesing a larger magnetic field strength, practically throughout the whole atmosphere. Neither significant gradients of the line-of-sight velocity, nor of the magnetic field inclination, are detected in any of the spots analysed. Two model atmospheres are given corresponding to hot (small) and cool (large) sunspots. The models are, to a large extent, free from effects of penumbral/photospheric stray-light because it is nearly absent in the large spots and because in the small one, where it is important for the Stokes I-profile, only Stokes V is considered to obtain the model atmosphere. These are the first umbral models in the literature for which a simultaneous determination of the magnetic field and thermodynamic stratifications is presented. The implications of these stratifications for the energy transport in sunspot umbrae are discussed. Title: Neuritogenesis: A model for space radiation effects on the central nervous system Authors: Vazquez, M. E.; Broglio, T. M.; Worgul, B. V.; Benton, E. V. Bibcode: 1994AdSpR..14j.467V Altcode: 1994AdSpR..14..467V Pivotal to the astronauts' functional integrity and survival during long space flights are the strategies to deal with space radiations. The majority of the cellular studies in this area emphasize simple endpoints such as growth related events which, although useful to understand the nature of primary cell injury, have poor predictive value for extrapolation to more complex tissues such as the central nervous system (CNS). In order to assess the radiation damage on neural cell populations, we developed an in vitro model in which neuronal differentiation, neurite extension, and synaptogenesis occur under controlled conditions. The model exploits chick embryo neural explants to study the effects of radiations on neuritogenesis. In addition, neurobiological problems associated with long-term space flights are discussed. Title: Variations of properties of the quiet photosphere along the equator and the central meridian: Spectroscopic results Authors: Rodriguez Hidalgo, I.; Collados, M.; Vazquez, M. Bibcode: 1994A&A...283..263R Altcode: Spectra of four lines (CI5380.3 A, MnI 5394.7 A, FeI 5930.2 A and SiI 5948.5 A) have been obtained in the quiet photosphere, at regular intervals along the polar axis and the equator. The spatially averaged spectra have been analyzed, studying the center-to-limb variation (CLV) and possible changes with the heliographic latitude of the residual intensity (RI), equivalent width (EW), full width at half line minimum (FWHM), and bisector of the line profiles. The aim of this spectroscopic study is to complete the photometric work carried out and recently published by the authors (Rodriguez Hildago et al. 1992, hereafter Paper I). It allows us to test some conclusions of Paper I and to extend our analysis to higher photospheric layers. Firstly the general behavior of the CLV is shown and discussed. From the comparison betwen the CLV along the North-South and East-West diameters, it is observed that the Cl line, formed very deep in the photosphere, broadens and shows raised minima with latitude, not showing variations in its EW, except at very high latitudes. The other three lines, which inform about the physical conditions in the middle photosphere, become deeper and stronger, and the FeI one seems broader, with latitude. The observational results are discussed in terms of physical scenarios based on changes in the velocity fields present in the photosphere (mainly of the granulation), possible spatial anisotropies in the distribution of network bright points (which would be related to differences in the mean temperature gradient) and the latitudinal variation of the granulation contrast found in Paper I. Title: Spatially highly resolved time series of solar granulation spectra. Authors: Hanslmeier, A.; Bonet, J. A.; Vazquez, M. Bibcode: 1994AGAb...10..114H Altcode: No abstract at ADS Title: The distribution of sunspot decay rates. Authors: Martinez Pillet, V.; Moreno-Insertis, F.; Vazquez, M. Bibcode: 1993A&A...274..521M Altcode: The distribution of sunspot decay rates is studied using the Greenwich Photoheliographic Results (GPR) for a total of approximately hundred years between 1874 and 1976.

The decay rates are seen to be lognormally distributed. The discrepancies between the decay rates given in the past by different authors are shown to originate as a consequence of this asymmetric distribution. It is pointed out that the extended tails shown by the lognormal distributions are associated to spots decaying much faster than suggested by Bumba's (1963) work. A cycle by cycle analysis of the lognormal distributions associated with each sunspot group type and for single spots is presented. The differences between the nine solar cycles involved are studied.

As a remarkable property of the decay process, we show that it happens at a nearly constant total to umbral area ratio. This property holds for decaying spots which are still large enough to show a penumbra.

We have studied the suitability of a decay law with the instantaneous decay rate proportional to the length of the spot boundary. This law predicts a parabolic decay pattern with some specific characteristics. No definite conclusion in favour of this law is reached, but it is suggested that a linear decay is as weakly supported by the GPR data as a peripheral one. On the other hand, weak non-linearities are seen in the decay of isolated spots with a clear tendency to produce a convex pattern in the area vs. time diagram. The implication is that sunspot decay is braked as time proceeds. Title: The continuum intensity-magnetic field relation in sunspot umbrae Authors: Martinez Pillet, V.; Vazquez, M. Bibcode: 1993A&A...270..494M Altcode: We describe the work carried out to obtain observational evidence of a local relation between the temperature and the magnetic field in different regions of several sunspots. Information about the temperature is extracted from the continuum intensity. The magnetic field is deduced by using the Stokes V profile of lines with different excitation potentials. A scaling relation between Stokes V and continuum intensity is used to estimate the stray-light contamination. The observed local relation between continuum intensity and magnetic field can be adapted to the equations describing magnetostatic horizontal force balance. The commonly accepted value for the Wilson depression suggests that the tension forces are as important as the magnetic pressure in defining horizontal equilibrium. The local relation observed holds for spatial scales larger than 1 arcsec. Evidence of unresolved hot magnetic regions inside the umbra is presented. Our study provides clues pointing to a dependence of continuum intensity with sunspot area. Small spots are seen to be brighter than big ones. Title: High Resolution Observations of Umbral Fine Structure Authors: Sobotka, M.; Bonet, J. A.; Vazquez, M. Bibcode: 1993ASPC...46...20S Altcode: 1993mvfs.conf...20S; 1993IAUCo.141...20S No abstract at ADS Title: The Continuum Intensity Magnetic Field Relation in Sunspot Umbrae Authors: Martinez Pillet, V.; Vazquez, M. Bibcode: 1993ASPC...46...60M Altcode: 1993mvfs.conf...60M; 1993IAUCo.141...60M No abstract at ADS Title: The Distribution of Sunspot Decay Rates Authors: Martinez Pillet, V.; Moreno-Insertis, F.; Vazquez, M. Bibcode: 1993ASPC...46...67M Altcode: 1993mvfs.conf...67M; 1993IAUCo.141...67M No abstract at ADS Title: On the correlation of power in sunspot umbral oscillations with continuum brightness Authors: Aballe Villero, M. A.; Marco, E.; Vazquez, M.; Garcia de La Rosa, J. I. Bibcode: 1993A&A...267..275A Altcode: We analyze time sequences of spectral lines formed at the photospheric level in order to study the correlation of umbral oscillations with continuum brightness and the influence of the fine structure and evolutionary stage of sunspots. The observations were taken using the Gregory-Coude Telescope (GCT) at the Observatorio del Teide (Tenerife). Power integrated in two frequency bands, 5 minutes (2.5-4.5 mHz) and 3 minutes (5-7 mHz), are used as parameters for this study. Our study yields the following results. A clear correlation exists between the power at the 3 minute band and the umbral brightness in dark cores. The light bridges do not follow this behavior. No correlation is apparent between the 5 minute power and the brightness. The same is obtained after normalization to the power in the adjacent light bridges. There is no correlation between the umbral oscillations of different umbral dark cores. The center-to-limb variation of the power (both bands) seems to support the interpretation of the umbral oscillations as slow body modes. Finally, we discuss the physical context of the observations. Title: Centre-to-limb variation of solar granulation along the equator and the central meridian Authors: Rodriguez Hidalgo, I.; Collados, M.; Vazquez, M. Bibcode: 1992A&A...264..661R Altcode: The paper analyzes white-light images of solar granulation taken outside active regions, at regular intervals along the polar axis and the equator, in order to study its center-to-limb variation and possible changes with the solar latitude. The 2D spatial power spectra of the brightness distribution are calculated and corrected for the distortions produced by the atmosphere and the telescope. One-dimensional integrated spectra are obtained for each position, with the geometrical foreshortening effect taken into account. A lower contrast, a smaller mean wavenumber, and a steeper center-to-limb variation of the contrast are found in the central meridian as compared to the equator. Sources of error are discussed, and different scenarios are presented in order to interpret these observational facts. Intensity fluctuations were detected until the extreme limb, with a spatial scale of about 10 arcsec. Title: Book-Review - Solar Observations - Techniques and Interpretation - First Canary Islands Winter School of Astrophysics Authors: Sanchez, F.; Collados, M.; Vazquez, M.; Staude, J. Bibcode: 1992AN....313Q.302S Altcode: No abstract at ADS Title: Spectroscopic determination of intensities of umbral bright features and adjacent background Authors: Sobotka, M.; Bonet, J. A.; Vazquez, M. Bibcode: 1992A&A...260..437S Altcode: Profiles of the Na I D doublet in three bright features (clusters of umbral dots), located in a relatively dark umbra, were analyzed by means of the 'local two-component modeling' to obtain the 'true' continuum intensities and temperatures of the bright features and their dark surroundings (background). The intensities of two central and one peripheral bright feature were 0.31 (background 0.11), 0.33 (0.13), and 0.40 (0.17), respectively. For the ratio of the object and background intensity (assumed to be constant, but unknown until now) the value of 2.6 +/- 0.2 was obtained. Title: On the relation between the intensities of bright features and the local background in sunspot umbrae Authors: Sobotka, M.; Bonet, J. A.; Vazquez, M. Bibcode: 1992A&A...257..757S Altcode: A photometric study of umbral bright features (umbral dots, clusters of umbral dots, bright grains of light bridges) in sunspots is presented. It is based on white-light images taken with a CCD video camera driven by an automatic image selection system. A direct linear relation between the observed brightness of the features and that of the surrounding background areas has been found. To eliminate the influence of the seeing on this result, the radiative fluxes, which are much less sensitive to the image degradation, have been examined and an analogous relation has been found. Finally, a possible physical explanation is suggested. Title: Book-Review - Solar Observations - Techniques and Interpretations Authors: Sanchez, F.; Collados, M.; Vazquez, M. Bibcode: 1992Sci...255.1757S Altcode: No abstract at ADS Title: Estimating the Degradation of Brightness Power Spectra of Solar Granulation from Images Outside the Disk Centre Authors: Rodriguez Hidalgo, I.; Collados, M.; Vazquez, M. Bibcode: 1992A&A...254..371R Altcode: A method is presented to estimate the influence of the atmospheric turbulence and the telescope on the mean power spectra of the granulation brightness distribution at positions outside the disk centre, derived using the determination of Fried's parameter.

The procedure is based on the differential degradation suffered by the directions perpendicular and parallel to the solar limb; the former one is more affected because it contains more power at high frequencies, due to the geometrical foreshortening effect. A certain spectral ratio is defined, which can be evaluated after the observed power spectra and can be described directly by a Korff's function for a given value of the Fried parameter r0. The best fit of the measured attenuation to the theoretical one is calculated, allowing to obtain the adequate Modulation Transfer Function to reconstruct the original power spectra. A test has been performed by evaluating the mentioned ratio after restored spectra showing that these present the required elongation up to a resolution of about 0".4. Title: Solar observations : techniques and interpretation Authors: Sanchez, F.; Collados, M.; Vazquez, M. Bibcode: 1992soti.book.....S Altcode: This book includes four chapters devoted to techniques and interpretation of solar observations. The chapter on high spatial resolution techniques considers basic concepts, single frame analysis, interferometry techniques, and other methods. The magnetic field measurements chapter discusses a prototype polarimeter, physical components of polarimeters, radiative transfer for polarized radiation, transfer equations for the Stokes parameters in a magnetized atmosphere, and magnetic field measurements in unresolved structures and in prominences. The chapter on solar postfocus instrumentation gives particular attention on the locations of postfocus instrumentation, postfocus imaging, spectrometers, detectors for spectrometers, and special instruments at spectrometer foci. The chapter on the dynamics of the solar atmosphere focuses on the features of the solar structure, diagnostic methods for velocity measurements, rotation and convection, motions in magnetic flux tubes and spots, and velocity fields in prominences and filaments. Title: Book-Review - New Windows to the Universe Authors: Sanchez, F.; Vazquez, M. Bibcode: 1991Sci...254.1667S Altcode: No abstract at ADS Title: Solar Observations Authors: Sánchez, F.; Collados, M.; Vazquez, M. Bibcode: 1991soob.book.....S Altcode: This book is a collection of papers by four internationally known speakers who explore some key areas in solar physics. O. von der Lühe discusses new techniques that are being developed for observing the sun at high spatial resolution and which have played a key role in most of the recent discoveries about the Sun. Egidio Landi Degl'Innocenti describes the magnetic field that dominates much of the structure we see and many of the active phenomena on the Sun. An understanding of how to measure the field is important. New solar telescopes in Europe and the United States have led the way in the present revolution in the understanding of the sun and important new breakthroughs are expected from LEST. In particular, the post-focus instrumentation has been crucial, and this is detailed by Hubertus Wohl; finally Pierre Mein writes about the solar atmosphere, which is now known to be a dynamic atmosphere with many puzzling features. Title: Asymmetries and shifts of the solar K I 7699 A line and possible evidence for gravity waves in the quiet photosphere Authors: Bonet, J. A.; Marquez, I.; Vazquez, M.; Woehl, H. Bibcode: 1991A&A...244..492B Altcode: A computing code has been developed to simulate the center-to-limb variation (CLV) of the bisector's shape, and absolute wavelength shift of the core in strong photospheric lines. Observational results concerning these aspects are also reported for the K I 7699 line. In the numerical simulation, granulation is represented, as a first approximation, by means of the granular model by Nelson (1978). It appears that granulation alone does not reproduce the observations and thus some modification has to be implemented in the dynamical model employed. A good match to the observed CLV of the wavelength shift of the line core is achieved by adding two 8-min period gravity waves with horizontal wavelength of the granular scale, the only difference between them being the sign of their horizontal wavenumber. Changes in the phase difference between the oscillating parameters have a decisive influence on the result. Title: Book-Review - New Windows to the Universe - 11TH European Regional Astronomy Meeting - V.1&2 Authors: Sanchez, F.; Vazquez, M. Bibcode: 1991JBAA..101..128S Altcode: No abstract at ADS Title: Solar Research at the I.A.C. Authors: Vazquez, M. Bibcode: 1991ApL&C..28..113V Altcode: 1991ApL....28..113V No abstract at ADS Title: Circular Polarization of the CA II H and K Lines in Solar Quiet and Active Regions Authors: Martinez Pillet, V.; Garcia Lopez, R. J.; del Toro Iniesta, J. C.; Rebolo, R.; Vazquez, M.; Beckman, J. E.; Char, S. Bibcode: 1990ApJ...361L..81M Altcode: A representative set of profiles is presented for the Ca II H resonace line in Stokes V and I, for the quiet sun, plages, sunspot umbrae, and a flare, as well as one example of the Ca II K line in a sunspot penumbra. The degree of polarization is highest in the spots and zero in the quiet sun, within error limits. The V profile asymmetries are, however, highest in the flare. The spectra of the Ca II K line are used to obtain a linear relation between V(lambda) and -dI/d(lambda) and a value for B(parallel) of 820 + or - 40 G using the weak-field approximation. Title: New windows to the universe Authors: Sanchez, F.; Vazquez, M. Bibcode: 1990Ap&SS.171.....S Altcode: Topics discussed in this issue include active galaxies and cosmology, interstellar and intergalactic medium, and astronomical instrumentation. Papers are presented on modeling rich clusters of galaxies, optical variability of NGC 7469 in 1967-1987, the structure of the broad line region in Fairall 9, the resolution of the compact core of quasars and active galaxies with the gravitational lens effect, and galaxy formation in pancake models. Consideration is also given to molecular clouds around outflow sources, modeling OH in regions of star formation, density studies of giant extragalactic H II regions, observations of the star formation region NGC 7129, and interstellar medium parameters derived from low-frequency variability. Other papers are on recent developments of IR array cameras in France, an automated astrographic plates measuring process, a low-resolution spectrophotometer for measuring the integrated color of galaxies, the HUS solar flare and cosmic gamma-ray burst detector aboard the Ulysses spacecraft, and the Grecos operating system of the GCT. Title: Decay rates of sunspot groups from 1874 to 1976 Authors: Martinez Pillet, V.; Moreno-Insertis, F.; Vazquez, M. Bibcode: 1990Ap&SS.170....3M Altcode: The global behaviour and fine structure of the distribution of sunspot decay rates from activity cycle 13 to 20 are presented. It is shown that the distribution of this parameter is lognormal. Statistically significantly lower values of decay rates are found in cycles 13, 14, and 18 for isolated spots. The complex groups had no appreciable changes. Title: Fried's Parameter Derived from Observations of Granulation Outside the Disk Centre Authors: Rodriguez Hidalgo, I.; Collados, M.; Vazquez, M. Bibcode: 1990Ap&SS.170..155R Altcode: A new method has recently been developed to obtain the Fried's parameter from observations of granulation outsude the disk centre, based on the different degradation suffered by the images on the directions parallel and perpendicular to the solar limb, due to the geometrical foreshortening. This procedure has been applied to CCD images obtained at the Swedish Solar Tower of the Observatorio del Roque de los Muchachos, with satisfactory results which are presented and discussed. Title: On the Continuum Intensity Magnetic Field Relation Along the Decay Phase of Sunspots Authors: Martinez Pillet, V.; Vazquez, M. Bibcode: 1990Ap&SS.170...75M Altcode: We present continuum intensity-magnetic field distributions for a decaying sunspot. It is shown that a very simple model accounts for the observed correlation. The Wilson depression is determined. Title: Oscillatory Behaviour in Sunspot Umbrae Authors: Aballe Villero, M. A.; Garcia de La Rosa, J. I.; Vazquez, M.; Marco, E. Bibcode: 1990Ap&SS.170..121A Altcode: Using a set of series of spectra of high spectral resoltion corresponding to the same umbra on several days, we have studied the oscillations related to evolution of the two main dark cores of it. We have detected differences in the behaviour of each core and an evolution in the power spectra not related with the external appearance of the spot. A quite constant value of the ratio of power at five minutes over three minutes has been found. Title: New windows to the universe; Proceedings of the Eleventh European Regional Astronomy Meeting, Universidad de la Laguna, Spain, July 3-8, 1989. Part II Authors: Sanchez, F.; Vazquez, M. Bibcode: 1990Ap&SS.170.....S Altcode: 1990Ap&SS.170...91S Recent observational and theoretical investigations of the sun and sunlike stars and of galactic structure and evolution are discussed in reviews and reports. Topics addressed include sunspot-group decay rates for 1874-1976, photometry and spectroscopy of solar granulation along the polar axis and equator, the quiescent radio emission of RS CVn binaries, and two-dimensional high-resolution spectroscopy of quiet regions on the sun. Consideration is given to spherical harmonics and Taylor harmonics in the kinematics of the solar neighborhood, radio observations of early-type galaxies with dust lanes, mean-field escapers in nonequilibrium systems, long-slit spectroscopy of the nuclear zone of NGC 253, the early nucleosynthesis of O and Fe, the structure and dynamics of two-dimensional oval configurations, and stochasticity in galactic models. Title: Photometry and Spectroscopy of the Solar Granulation Along the Polar Axis and Equator Authors: Rodriguez Hidalgo, I.; Collados, M.; Vazquez, M. Bibcode: 1990Ap&SS.170...23R Altcode: From high-resolution CCD images of granulation obtained at the Swedish Solar Tower of the Observatorio del Roque de los Muchachos at different positions on the solar disk, mean bi-dimensional spatial power spectra have been obtained at each position and restored following the method proposed by Rodríguez Hidalgoet al. (1990). The variation with latitude of the power spectrum, of the granular brightness contrast and of the mean wave number of the power spectrum are presented. The analysis is completed with spectroscopic observations obtained at the Gregory Coudé Telescope of the Observatorio del Teide. The centre-to-limb and latitudinal variation of the bisectors, residual intensities and equivalent widths are shown for several photometric lines. Title: New windows to the universe. Vol.1, Vol.2 Authors: Sanchez, F.; Vazquez, M. Bibcode: 1990Ap&SS.169.....S Altcode: Papers are presented on stellar structure and evolution. Particular attention is given to the deep CCD photometry of stars in the globular cluster M3; dynamical instability in accreting white dwarfs; the IR photometry of open clusters; stellar mass loss in late B-type supergiants; and multicolor photopolarimetry of magnetic catalysmic variables. Consideration is also given to white dwarfs with magnetic field and differential rotation, phase shifts between colors in pulsating stars, axion decay in a strong magnetic field and radio fluxes from magnetic white dwarfs, and line transfer in supernovae envelopes. Title: Preface Authors: Sanchez, F.; Vazquez, M. Bibcode: 1990Ap&SS.169D...9S Altcode: No abstract at ADS Title: Stray-light measurements at the Observatorio del Teide Authors: Martinez Pillet, V.; Ruiz Cobo, B.; Vazquez, M. Bibcode: 1990SoPh..125..211M Altcode: A new procedure to separate the instrumental and atmospheric components of stray light is presented. It is based on the dependence of the aureole's atmospheric component on the air mass and is applied to measurements taken with the Vacuum Newton Telescope (VNT) at the Observatorio del Teide (Tenerife). The resulting instrumental part is independent of the air mass. The variation of both components with wavelength is also studied. The instrumental component shows no dependence on wavelength, in contrast to the atmospheric one which is greater in the blue than in the red. It is concluded that observations with air masses larger than two will probably be strongly affected by stray light. Title: Comparison of heliographic sunspot coordinates observed with seven different solar telescopes. Authors: von Alvensleben, A.; Casas, R.; Csepura, G.; Lustig, G.; Otruba, W.; Schroll, A.; Vazquez, M.; Wittmann, A. D.; Wöhl, H. Bibcode: 1990AGAb....5...43V Altcode: No abstract at ADS Title: New windows to the universe. Volumes I, II. Invited review papers and general lectures. Authors: Sanchez, F.; Vazquez, M. Bibcode: 1990nwtu.book.....S Altcode: Contents: Vol. I: The Sun and solar-like stars. Stellar structure and evolution. Astronomical instrumentation. General lectures. Vol. II: Structure and evolution of galaxies. Active galaxies and cosmology. Interstellar and intergalactic medium. Title: New Windows to the Universe, Set, XIth European Meeting of the International Astronomical Union Authors: Sanchez, F.; Vazquez, M. Bibcode: 1990nwus.book.....S Altcode: 1990nwus....2.....S No abstract at ADS Title: Book-Review - the Role of Finescale Magnetic Fields on the Structure of the Solar Atmosphere Authors: Schroter, E. H.; Vazquez, M.; Wyller, A. A.; Wiedemann, E. Bibcode: 1989AN....310..318S Altcode: No abstract at ADS Title: A statistical study of the decay phase of sunspot groups from 1874 to 1939 Authors: Moreno-Insertis, F.; Vazquez, M. Bibcode: 1988A&A...205..289M Altcode: A statistical study of the decay of sunspots and sunspot groups is carried out using data contained in the Greenwich Photoheliographic Results. The period studied spans more than six decades, namely from 1874 to 1939. The adequacy of exponential, quadratic and linear decay laws to the area decay data is considered. The dependence, or otherwise, of the mean area decay rate for each single spot, D, on its maximum area, A0, is studied; no relationship of the form D(A0) can be ascertained. In fact, when plotted on a D vs. A0 diagram, the couples (A0, D) cluster in two pencils issuing from the origin of coordinates. These two clusters can be seen to correspond with the families of the recurrent and non-recurrent spot groups. The adequacy of a quadratic law to the decay data is considered. A most probable parabolic decay law is obtained; this law corresponds to the case in which the decay rate is proportional to the spot perimeter. Finally, the variation of the decay rates in successive activity cycles is also discussed. Title: Book-Review - the Role of Finescale Magnetic Fields on the Structure of the Solar Atmosphere Authors: Schroter, E. H.; Vazquez, M.; Wyller, A. A. Bibcode: 1988S&T....76R.264S Altcode: No abstract at ADS Title: Temporal and center-to-limb variations of the K I 769.9 NM line profiles in quiet and active solar regions Authors: Bonet, J. A.; Marquez, I.; Vazquez, M.; Woehl, H. Bibcode: 1988A&A...198..322B Altcode: The temporal and spatial behaviour of the K I 769.9 nm solar line are investigated using several series of high spectral resolution low-noise photoelectric scans obtained at Kitt Peak National Observatory in quiet and active (plages and sunspots) regions. Corrections due to the instrumental profile were applied to yield the best line shape. A systematic center-to-limb investigation of the behaviour of the line shape was performed in quiet regions. Power and phase spectra of the main parameters defining the line shape have also been determined. Within several umbrae at different cos θ positions, an inverse C-shape or even an "S"-shape of the bisectors was found. Title: Photometry of sunspot penumbrae Authors: Collados, M.; del Toro Iniesta, J. C.; Vazquez, M. Bibcode: 1988A&A...195..315C Altcode: The authors present the results of a statistical analysis of the penumbra of sunspots. The intensity distribution, and several parameters derived from it, is analysed at different heliocentric angles and positions on the spot. It has revealed, on the one hand, that a two-component model is compatible with the observations and that both components lie at the same height, and on the other, that the penumbral asymmetry found by Collados et al. (1987) is confirmed under a photometrical point of view, the western penumbra being slightly shorter than the eastern one. Title: On the Age Dependence of the Asymmetry of Penumbrae of Sunspots Authors: Collados, M.; del Toro Iniesta, J. C.; Vazquez, M.; Woehl, H. Bibcode: 1988SoPh..117..199C Altcode: The age dependence of the recently described asymmetry of penumbrae of large stable sunspots was analyzed. Young sunspots showed shorter eastern penumbrae, which differed by a maximum of ± 10 % from their mean width. For older sunspots the western penumbrae became smaller than the mean penumbra reaching differences of 20 % for spots of two months age. Title: Coordination of Astronomical Observations at the Canary 1049.01-ISLANDS Authors: Sanchez, F.; Vazquez, M. Bibcode: 1988copa.conf..181S Altcode: The Instituto de Astrofisica de Canarias has two observatories on the Canary Islands; Roque de los Muchachos Observatory on La Palma and Teide Observatory, on Tenerife. In this contribution the authors explain the guidelines for the allocation of this observing time and mention some of the future plans for remote observing and control of the telescopes. Title: A Statistical Study of the Geometrical Wilson Effect Authors: Collados, M.; del Toro Iniesta, J. C.; Vazquez, M. Bibcode: 1987SoPh..112..281C Altcode: An analysis has been carried out of the centre-to-limb variation of the apparent sizes of the umbra, penumbra and whole spot. It has revealed that the umbral size decreases with height. We have interpreted this result in terms of the penumbral geometrical height scale. A value of 230 km, which is larger than that of the photosphere or the umbra, explains the observed decrease. An intrinsic asymmetry in the penumbra of old sunspots has also been found, the western penumbra being slightly shorter that the rest of the penumbra. This explains why the inverse Wilson effect is present, preferentially, in the western hemisphere, as found in previous investigations. A comparison with other works is also made. Title: A new determination of the solar granulation contrast Authors: Collados, M.; Vazquez, M. Bibcode: 1987A&A...180..223C Altcode: The contrast of the photospheric granulation in the centre of the disk at a wavelength of 500 nm has been determined by means of photographs taken during the solar eclipse of May 30th 1984. After restoration, values of 17.3% and 20.4%, using the sum of two lorentzians to define the instrumental profile, and of 11.7% and 14.3%, using the sum of two gaussians, have been obtained. This suggests that the results are quite sensitive to the particular choice which is made of the analytical approximation to the point spread function. The corrected power spectrum does not show significant differences to those of previous works. A comparison between the method for correcting the image degradation which the authors propose with those used by other investigators is also made. Title: Variation of the granulation with the solar latitude. Authors: Collados, M.; Rodriguez Hidalgo, I.; Vazquez, M. Bibcode: 1987PAICz..66...41C Altcode: 1987eram....1...41C Preliminary results of a search for the variation of the solar granulation properties with the heliographic latitude are presented. Within errors, no changes are found in the power spectra and sizes between N-S and E-W scans. Title: Granulation Deformation Near and in Sunspot Regions Authors: Collados, M.; Marco, E.; del Toro, J. C.; Vazquez, M. Bibcode: 1986SoPh..105...17C Altcode: High-resolution white-light pictures are analyzed to study the differences between the granular size near sunspot penumbrae and in light-bridges presenting granular structure and that of the quiet photosphere. No difference is found between the mean granular diameter in light-bridges and the quiet photosphere. The dispersion found in the results corresponding to different zones around the sunspots indicates that the size of the granulation may vary from place to place near the sunspots, its mean value not differing significantly from that of the quiet photosphere. A possible systematic bias in the selection of the granules by Macris (1979) is found. Title: Differential rotation of sunspot groups in the period from 1874 through 1976 and changes of the rotation velocity within the solar cycle Authors: Balthasar, H.; Vazquez, M.; Woehl, H. Bibcode: 1986A&A...155...87B Altcode: An effort is made to determine the differential rotation of the sun on the basis of the complete sample (1874-1976) of the Greenwich Photoheliographic Results. In order to improve the representation of differential rotation, a modified fit formula whose constant lies at 15 deg latitude (where sunspots nearly always occur) is introduced. Rotation is noted to strongly depend on sunspot type, with C-groups exhibiting high velocities and H- and J-spots the lowest ones. The new fit formula indicates that the highest velocity is found around the minima; at the beginning of an activity maximum, there is a secondary velocity maximum. The lowest velocities lie between the activity maximum and minimum. The braking of recurrent sunspots is confirmed. Title: Observations of the Birth and Fine Structure of Sunspot Penumbrae Authors: Collados, M.; Garcia de La Rosa, J. I.; Moreno-Insertis, F.; Vazquez, M. Bibcode: 1985LNP...233..133C Altcode: 1985hrsp.proc..133C High resolution white-light pictures of sunspot penumbrae are presented. These include pictures showing details of their filamentary structure and some instances of the birth of a penumbra. The observations are discussed in the framework of current penumbra theories. Title: Photometry of Light-Bridges in Sunspots Authors: Collados, M.; Marco, E.; Vazquez, M. Bibcode: 1985LNP...233..299C Altcode: 1985hrsp.proc..299C The decay of a sunspot region was studied using high resolution white-light pictures. The photometric and geometric parameters of a light-bridge showing granular structure were determined. No difference is found comparing it with the quiet photosphere. Title: The response of the line KI 7699 to the solar oscillations Authors: Marmolino, C.; Roberti, G.; Severino, G.; Vazquez, M.; Woehl, H. Bibcode: 1984ESASP.220..191M Altcode: 1984ESPM....4..191M The time behavior of the KI 7699 line profile in presence of acoustic-gravity waves with periods of 300, 180, and 30 sec was studied. The response of the line to the waves depends strongly on the period and is not linear for the 30 sec wave. The height increase of the amplitude in the longer period waves explains the observed anticorrelation between line asymmetry and line core shift. The time averaged profile for the 30 sec wave has a red shifted line core. This could account for the lowest part of the C shaped solar bisectors. Title: New information about solar rotation Authors: Woehl, H.; Balthasar, H.; Koch, A.; Kueveler, G.; Roca-Cortes, T.; Schmidt, W.; Vazquez, M. Bibcode: 1984S&W....23...73W Altcode: It is pointed out that the phenomenon of solar rotation is known since the introduction of the telescope into astronomy by Galilei in 1610. Regular measurements concerning the positions of sunspots were conducted with the aid of photographic plates at the Royal Greenwich Observatory during the time from 1874 to 1976. The obtained data provide an excellent basis for statistical analysis. Information obtained as a result of such analyses is discussed. Attention is given to the determination of the Wilson depression, details regarding solar differential rotation, plans for an evaluation of data with the aid of a computer, the rotation of the solar plasma, a comparison of sunspots and plasma, the theory of differential rotation, and new information concerning solar rotation partly obtained with the aid of solar telescopes in a Spanish observatory on the island of Tenerife. Title: The Age Decay of Stellar Magnetic Activity in MS Field Solar Type Stars Authors: Cabestany, J.; Vazquez, M. Bibcode: 1983Ap&SS..97..151C Altcode: The age decay of two indicators of the stellar magnetic activity (λ 2800 Mg ii emission flux and λ 10830 He i equivalent width) have been studied for field solar-type stars. The Li abundance has been used, in most of the cases, as a stellar age indicator. A calibrated decay law for Mg ii has been determined and compared with a similar one, recently published, for the Ca ii K emission. The greater scatter in the He i results is atributed to the different rotation rates. Title: Space and time variations of KI 7699 solar line profile Authors: Roca-Cortes, T.; Vazquez, M.; Woehl, H. Bibcode: 1983SoPh...88....1R Altcode: The temporal and spatial behaviour of the KI7699 line profile is investigated. In particular we have measured the asymmetries of the line profile at several residual intensities using the bisector method. We find, in the bisector of the mean line profile, similar shapes as those obtained before for different positions on the solar disk. However the strong variations of the bisector found with time and geometry of input aperture, warns us against the use of the mean or integrated profiles (either in time or space). Moreover, we find an anticorrelation between the asymmetry in the line profile at different residual intensities and the shift, found as the distance to a terrestrial line, for any position observed on the solar disk. No limb effect for this line is found, within errors. Title: Erratum - Differential Rotation and Meridional Motions of Sunspots from 1874 TO 1902 Authors: Arevalo, M. J.; Gomez, R.; Vazquez, M.; Balthasar, H.; Wohl, H. Bibcode: 1983A&A...117..170A Altcode: No abstract at ADS Title: Introduction to the theory of stellar atmospheres Authors: Vazquez, M. Bibcode: 1983STIN...8331559V Altcode: The fundamental equations of continuity and transport, the Eddington approximation, the excitation, ionization and absorption processes, the formation of spectral lines, and the models of stellar atmospheres are described. Convection in the stellar atmosphere is discussed including the Schwarzschild criterium, the computation of velocity fields, and the characteristics of chromospheres and coronas. Title: Differential rotation and meridional motions of sunspots from 1874 to 1902 Authors: Arevalo, M. J.; Gomez, R.; Vazquez, M.; Balthasar, H.; Woehl, H. Bibcode: 1982A&A...111..266A Altcode: Position data of sunspot groups from the period 1874-1902 are used to investigate the differential rotation of the Sun and the meridional motions of the sunspots. The equatorial velocity is higher than in the period 1940-1968 investigated by Balthasar and Wöhl (1980), while differences between the northern and southern hemispheres are less. For cycle 12 we find meridional motions towards north while in cycle 13 the motions are directed towards south like in the period 1940-1968. Our other results are comparable to those of Balthasar and Wöhl (1980) for the period 1940-1968. Title: On the Width Distribution of Penumbral Filaments in Sunspots Authors: Bonet, J. A.; Ponz, J. D.; Vazquez, M. Bibcode: 1982SoPh...77...69B Altcode: The mean width and distribution of penumbral filaments of a sunspot have been estimated, using white light photographs obtained with a vacuum, Newtonian type, telescope. Three areas corresponding to the penumbra of a sunspot have been analysed. Data were collected during the solar eclipse of June 1973. The photometric profiles of the Moon limb over the photosphere have been analysed to obtain useful information on both, atmospheric and instrumental perturbation on each exposure. The mean value of the width of penumbral filaments is 0.37 arc sec. Title: A model for constructing artificial integrated spectral lines and their Fourier transform properties relevant to the search for differential rotation of stars Authors: Garcia-Alegre, M. C.; Vazquez, M.; Woehl, H. Bibcode: 1982A&A...106..261G Altcode: A model is given for constructing artificial integrated spectral lines which allows the inclusion of all effects relevant to the synthesis of these lines by numerical methods. Among the effects included are noise, limb darkening, the centre-to-limb variation of the shapes and wavelength positions of the spectral line profiles, different laws of the differential rotation and a tilting of the rotating star.

Fourier transformation of the artificial integrated spectral lines is applied to decide whether the different effects may influence the possibility of detecting stellar differential rotation by the method of Gray (1977). Title: IUE MG II doublet observations in F and G main sequence stars. Authors: Garcia-Alegre, M. C.; Ponz, J. D.; Vazquez, M. Bibcode: 1981A&A....96...17G Altcode: Mg II resonance lines at 2800 A were studied in the spectra of F and G main sequence stars, observed with the IUE satellite in high resolution mode. Correlation with other chromospheric indicators were investigated and a search was conducted for the best candidates to continue further studies of differential rotation. An attempt has been made to see whether there is a unique relation between the logarithm of the Mg II k emission line width and the absolute visual magnitude, independent of luminosity and emission strengths, as derived for the Ca II K emission line. Title: Large-Scale Solar Motions as Determined by Doppler Shift Measurements Using a Linear Photodiode Array Authors: Perez Garde, M.; Vazquez, M.; Schwan, H.; Woehl, H. Bibcode: 1981A&A....93...67P Altcode: 1981MiABB..96...67P Doppler shifts of the solar Fe line 630.15 nm relative to the terrestrial O2 line 630.2 nm were determined at many positions on the solar disk to investigate the rotation of the solar plasma and locate large-scale plasma motions. The spectrum was measured by a self-scanning linear photodiode array with 128 diodes; and average rotation velocity of (2.881 plus or minus 0.027) microrad/s was found at the solar equator in September 1978, and large-scale velocity pattern occurred between plus 40 and minus 30 deg in latitude with a period of 45 deg in longitude during Sept. 6 to 13, 1978. Title: An Umbral Brightening Associated with a Two-Ribbon Flare Authors: Vazquez, M.; Herrera, F. Bibcode: 1979SoPh...64..329V Altcode: We report an unusual case of a two-ribbon flare associated with an umbral brightening in a magnetically unipolar region. Title: An attempt to compare the differential rotation of the Ca+-network with that of the photospheric plasma. Authors: Schroeter, E. H.; Woehl, H.; Soltau, D.; Vazquez, M. Bibcode: 1978SoPh...60..181S Altcode: In this third paper of a series we report on results obtained from almost simultaneous observations of the differential rotation of the Ca+-chromosphere and the photospheric plasma. The observations (tracings of Ca+-mottles, Doppler-shift-measurements in a photospheric line) were performed at the Locarno station during two extended periods in 1976. Both data sets were used to search for a large scale circulation pattern. A regular long-lived pattern could not be detected, but a single cell with radial outflow (∼40 ms-1) extending over more than 50° in longitude has been found. Statistically significant temporal changes of the differential rotation law of the Ca+-chromosphere correlated with changes of meridional motions and differences in the rotation of the two hemispheres were observed. The data of 1976 show no significant difference in the equatorial velocity of the Ca+-chromosphere and the photosphere. A comparison of temporal variations of the rotation velocity of the Ca+-mottles and the photospheric plasma yielded no significant correlation. Finally, we correlated the measurements of the photospheric rotation performed within the equatorial belts at Locarno with those obtained at Mt. Wilson by a different method during the same periods. The Locarno data show small temporal variations (±50 m-1s) with no correlation between the two hemispheres, while from the Mt. Wilson data larger variations (±100 m s-1) with a very high correlation between the two hemispheres have been found. A comparison of both sets of data yielded no correlation at all demonstrating the need for further coordinated observations and a drastic increase of internal accuracy. Title: Flamenco Sounding Rocket Authors: Simon, J.; Mateo, A.; Vazquez, M. Bibcode: 1976ESASP.115..541S Altcode: 1976epsr.conf..541S No abstract at ADS Title: Differential Rotation and the Spot Zones Authors: Deubner, F. -L.; Vazquez, M. Bibcode: 1975SoPh...43...87D Altcode: A minimum of angular velocity is not found at the equator as suggested by Gilman, but at a latitude of 6° in both hemispheres. Title: Aspectos magneticos de la evolucion de las manchas solares. Authors: Casanovas, J.; Vazquez, M.; Bonet, J. A. Bibcode: 1974UrBar..59...79C Altcode: The spectroscopic determinations of the solar magnetic fields are based on the Zeeman effect observed in relation to a number of absorption lines of the solar spectrum. It is attempted to deduce indirectly certain characteristics of the magnetic field in a sunspot, giving attention to morphological aspects and the magnetic polarities. The results of the investigation are illustrated with the aid of a number of pictures. Title: A Morphological Study of the Light-Bridges in Sunspots Authors: Vazquez, M. Bibcode: 1973SoPh...31..377V Altcode: This study is based on photographs taken during the period March 1971 to June 1972. Various morphological features observed are described and their possible role in sunspot evolution discussed. It is pointed out that a light-bridge looks like the re-establishment of photospheric-like conditions.