Applications of expert systems for satellite autonomy

Some aspects of the on-board application of expert systems in artificial satellites are discussed. The activities of the study, which include the implementation of two prototypes on a dedicated artificial intelligence machine, are described. The general implications of the experience are then discussed. These concern the interrelationship between the expert system and the architecture of the satellite and the expert system's impact on the mission definition phase of the satellite lifecycle. The main obstacles that need to be overcome before operational use of onboard expert systems can take place are discussed

The BL-Lac gamma-ray blazar PKS 0447-439 as a probable member of a group of galaxies at z=0.343

The BL-Lac blazar PKS 0447-439 is one of the brightest HE gamma-ray sources that were first detected by Fermi-LAT. It was also detected by H.E.S.S. at VHE gamma-rays, which allowed constraining the redshift of PKS 0447-439 by considering the attenuation caused by gamma-ray interactions with ambient photons in the extragalactic background light (EBL). This constraint agreed with color-magnitude and spectroscopic redshift constraints (0.179 < z < 0.56), Recently, however, a much higher redshift was proposed for this blazar (z > 1.2). This value was debated because if true, it would imply either that the relevant absorption processes of gamma-rays are not well understood or that the EBL is dramatically different from what is believed today. This high redshift was not confirmed by three independent new spectroscopic observations at high signal-to-noise ratios. Given that BL-Lac are typically hosted by elliptical galaxies, which in turn are associated with groups, we aim to find the host group of galaxies of PKS 0447-439. The ultimate goal is to estimate a redshift for this blazar. Spectra of twenty-one objects in the field of view of PKS 0447-439 were obtained with the Gemini Multi-Object Spectrograph. Based on the redshifts and coordinates of these galaxies, we searched for groups of galaxies. Using a deep catalog of groups, we studied the probability of finding by chance a group of galaxies in the line of sight of PKS 0447-439. We identified a group of galaxies that was not previously cataloged at z = 0.343 with seven members, a virial radius of 0.42 Mpc, and a velocity dispersion of 622 km s^-1. We found that the probability of the host galaxy of PKS 0447-439 to be a member of the new group is >= 97%. Therefore, we propose to adopt z = 0.343 +- 0.002 as the most likely redshift for PKS 0447-439.Comment: Accepted for publication in A&

BEHAVIOURAL PHENOTYPE AND ELECTROENCEPHALOGRAPHIC PROFILE OF ADOLESCENT AND ADULT SNAP-25+/- MUTANT MICE.

Synaptosomal-associated protein of 25 kDa (SNAP-25) is a protein that participates in the regulation of synaptic vesicle exocytosis through the formation of the soluble N-ethylmaleimide-sensitive proteine (NSF) attachment protein receptor complex and modulates voltage-gated calcium channels activity. Snap25 gene has been associated with schizophrenia, and bipolar disorder, and lower levels of SNAP-25 have been described in patients with schizophrenia. In particular several SNAP-25 intronic single polymorphisms were linked to attention de\ufb01cit hyperactivity disorder, one of the most common neuropsychiatric diseases among children and adolescents. The most animal models of this pathology, available until now, are characterized by reduced SNAP-25 level in the CNS: the coloboma mice, and the spontaneously hypertensive rats (SHR). However none of them can completely ricapitulate all the core features of the human patology. Thus we used adult SNAP-25 heterozygous (SNAP-25+/ 12) mice in comparison with age-matched wild type mice (SNAP-25+/+) to investigate at which extent the reduction of the protein levels affects neuronal network function and mouse behavior, and the possible therapeutic effect of antiepileptic drugs. We also characterized adolescent SNAP-25+/- mice (6-7 weeks) in order to evaluate if they can be considered a new ADHD animal model. Firstly we analysed general health, sensory and motor abilities, and emotional behaviour in our animals, without finding any abnormalities in heterozygous mice. Since altered SNAP-25 level were associated with cognitive deficit, we performed T-maze test for the evaluation of spatial memory, latent inhibition test for attention, conditioned taste aversion and object recognition for associative memory. SNAP-25+/- resulted impaired in associative but not in spatial memory, probably because of the heterogeneous protein expression levels in different hippocampal areas, being more expressed in CA3, known to play a key role in associative memory, than in CA1, critical for long-term spatial memory. SNAP-25+/- has been associated to disease characterized by altered social behaviour, such as schizophrenia and bipolar disorder. We tested SNAP-25 mutant mice in sociability and social novelty test. Heterozygous showed impairment both in sociability and in social recognition. Pathologies characterized by SNAP-25 alterations show signi\ufb01cantly higher incidence of epilepsy. For this reason we recorded the cortical electric activity of mice and we found that SNAP-25 levels reduction was associated with network hyperexcitability, in terms of spike activity, which did not lead to spontaneous epileptiform behaviour. Acute treatment with antiepileptic drugs and Ca2+ antagonist normalized cerebral activity. Among these drugs, sodium valproate was more effective in blocking EEG and behavioural deficits. Since it is known the correlation between EEG alteration and cognitive deficits we can hypothesize that the mnemonic and social deficit are due to the abnormal EEG profile. Adolescents SNAP-25+/- mice showed the same deficits found in the adults. They also were hyperactivite, and were not susceptible to d-amphetamine treatment. These results are in line with the characteristic phenotype of ADHD children, that display cognitive deficits, problems in socialization and hyperactivity, normalized by stimulants. Recently EEG analysis was used as diagnostic tool to discriminate ADHD from other neuropsychiatric diseases. EEG in ADHD children is characterized by spikes and alteration in spectral power bands frequency. Spectral analysis heterozygous mice EEG recordings was caharacterized by spikes, a decrease in fast waves and a parallel increase in slow waves, as occur in ADHD children. Repeated exposition to a VLP solution (0.1%) reduced all the behavioural deficit and was effective in blocking spike activity for two weeks, when discontinued. SNAP-25+/- mice seem to be a promising ADHD animal model, able to recapitulate almost all the core symptoms of the human disease. Repeated treatment with VLP resulted effective in all the tests carried out in adolescents mice, in line with recent findings of its therapeutic effects on ADHD symptoms in x-fragile syndrome

CMB signal in WMAP 3yr data with FastICA

We present an application of the fast Independent Component Analysis (FastICA) to the WMAP 3yr data with the goal of extracting the CMB signal. We evaluate the confidence of our results by means of Monte Carlo simulations including CMB, foreground contaminations and instrumental noise specific of each WMAP frequency band. We perform a complete analysis involving all or a subset of the WMAP channels in order to select the optimal combination for CMB extraction, using the frequency scaling of the reconstructed component as a figure of merit. We found that the combination KQVW provides the best CMB frequency scaling, indicating that the low frequency foreground contamination in Q, V and W bands is better traced by the emission in the K band. The CMB angular power spectrum is recovered up to the degree scale, it is consistent within errors for all WMAP channel combination considered, and in close agreement with the WMAP 3yr results. We perform a statistical analysis of the recovered CMB pattern, and confirm the sky asymmetry reported in several previous works with independent techniques.Comment: 10 pages, 7 figures, submitted to MNRA

Climate change, agriculture and migration: A survey

This paper proposes a selective review of the classical economics-based literature on climate change and migration, focusing on the extent to which agriculture might be considered a key mediating channel linking climate change to migration. Overall, climate change is expected to have large and negative effects on the global economy. These effects are even more evident whenever the economic sector considered is the agricultural one, particularly in developing countries. Hence, migration can be viewed as a specific form of adaptation implemented by individuals and households, enabling them to cope, among other things, with weather-induced risk. We show that the importance of agriculture emerges from both plenty of micro-level country studies and relatively few macro-level analyses using cross-sectional data over longer time periods. Thus, policy actions targeted to sustainable agriculture and rural development can both help tackle the challenges posed by climate change and create opportunities in the face of growing migration issues. However, we also stress that much of the current evidence is based on statistical associations that have nothing to do with causal inferences. This calls for the use of a more structural approach and more sophisticated research designs, enabling the researchers to better discriminate among different mechanisms concurrently at work. In addition, further research should be addressed to the role played by food security, a complex dimension largely missing in the current debates on climate change and migration

Role of meteorological factors on SARS-CoV-2 infection incidence in Italy and Spain before the vaccination campaign. A multi-city time series study

Numerous studies have been conducted worldwide to investigate if an association exists between meteorological factors and the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infection incidence. Although research studies provide conflicting results, which can be partially explained by different methods used, some clear trends emerge on the role of weather conditions and SARS-CoV-2 infection, especially for temperature and humidity. This study sheds more light on the relationship between meteorological factors and SARS-CoV-2 infection incidence in 23 Italian and 52 Spanish cities. For the purposes of this study, daily air temperature, absolute and relative humidity, wind speed, ultraviolet radiation, and rainfall are considered exposure variables. We conducted a two-stage meta-regression. In the first stage, we estimated the exposure-response association through time series regression analysis at the municipal level. In the second stage, we pooled the association parameters using a meta-analytic model. The study demonstrates an association between meteorological factors and SARS-CoV-2 infection incidence. Specifically, low levels of ambient temperatures and absolute humidity were associated with an increased relative risk. On the other hand, low and high levels of relative humidity and ultraviolet radiation were associated with a decreased relative risk. Concerning wind speed and rainfall, higher values contributed to the reduction of the risk of infection. Overall, our results contribute to a better understanding of how the meteorological factors influence the spread of the SARS-CoV-2 and should be considered in a wider context of existing robust literature that highlight the importance of measures such as social distancing, improved hygiene, face masks and vaccination campaign

Light and Laser Scanning Microscopy analysis of hydroxyapatite used in periodontal osseous defects in man: evidence of a different resorption pattern in bone and soft tissues

Hydroxyapatite (HA) is a highly biocompatible material that recently has been shown to undergo biodegradation. The mechanisms of this phenomenon are unclear, and humoral and cellular events have been thought to be implicated. In the present study HA particles were put into infraosseous defects on teeth that were to be extracted for prosthetic reasons and then retrieved after a 1 year period. The specimens were processed with the cutting grinding system. Results show a very sharp difference of the biodegradation processes, related to the tissues that surround the HA particles. HA in tight contact with mineralized bone showed no evidence of degradation or resorption, while on the contrary, in the areas where bone loose connective tissue was present, it was possible to observe HA crystals detached and scattered in cells cytoplasm or extracellular fluids. This dissolution and resorption phenomenon were observed also by Laser Scanning Microscope (LSM) in fluorescent mode. These differences in degrees of degradation between bone and loose connective tissue could be due to the small amount of interstitial fluid present in mineralized bone and the greater flow of fluid through connective tissue.L’hydroxyapatite (HA) est un matériel hautement biocompatible qui s’est révélé récemment capable de subir une biodégradation. Le mécanisme de ce phénomène n’est pas clair, et semble impliquer une particination humorale et cellulaire. Notre recherche a porté sur la mise en place de particules d’HA dans des défects intraosseux en rapport avec des dents qui doivent être extraites pour des raisons prothésiques, et sur leur etude suite à leur ablation un an après. Les résultats ont démontré des différences marquées dans le processus de dégradation en rapport avec les tissus qui entourent l’HA. Les particules d’HA qui sont en contact avec l’os minéralisé ne présentent pas de signes de dégradation ou de résorption, tandis que dans les régions où du tissu conjonctif était présent, il est possible d’observer des cristaux d’HA détachés et dispersés dans le cytoplasme des cellules et dans le liquide extracellulaire. Ces phénomènes de dissolution et de résorption ont été également étudiés au Microscope Electronique à Balayage au Laser en fluorescence. Ces différences dans le degré de dégradation observés dans l’os et dans le tissu conjonctif lâche pourraient être dues à la faible quantité de liquide interstitiel dans l’os minéralisé et à la quantité plus grande de flux liquidien dans le tissu conjonctif

On the redshift of the gamma-ray blazar PKS 0447-439: Optical spectroscopy using Gemini observations with high S/N ratio

Abstract: The BL-Lac blazar PKS 0447-439 was detected at very high energy gamma-rays by HESS following the discovery by Fermi-LAT. The lack of both emission and absorption lines in BL-Lacs make the estimation of their redshifts very difficult. Modeling the drop in gamma-ray spectra it was possible to have an estimation of redshift for PKS 0447-439 of z approx 0.2, which is compatible with the value z=0.205 reported by the identification of Ca II absorption lines in optical spectra. By the identification of a weak line of Mg II using spectra with average signal-to-noise S/N approx 80, it has been recently reported a lower limit for the redshift of this blazar of z&lt;=1.246. Triggered by this controversy, we have proposed new optical observations with the Gemini South telescope to perform further spectroscopic analysis with very high S/N ratio (approx 200-500). In this work we present a new optical spectrum of PKS 0447-439, and report on the analysis and results of such observations. Even with this significantly high quality signal we were not able to identify any spectral features to allow an estimation of the redshift. In agreement with other recent studies, we identify the Mg II line reported previously as originated in the Earth´s atmosphere, and conclude the lower limit of the redshift is incorrect. More interestingly, we could not identify the Ca II absorption lines used to report a redshift of 0.205.Fil: Donzelli, Carlos. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba; Argentina.Fil: Donzelli, Carlos. Conicet. Instituto de Astronomía Teórica y Experimental; Argentina.Fil: Muriel, Hernán. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba; Argentina.Fil: Muriel, Hernán. Conicet. Instituto de Astronomía Teórica y Experimental; Argentina.http://adsabs.harvard.edu/abs/2013arXiv1307.6907RAstronomía (incluye Astrofísica y Ciencias del Espacio