New Signatures of the Milky Way Formation in the Local Halo and Inner Halo Streamers in the Era of Gaia

We explore the vicinity of the Milky Way through the use of spectro-photometric data from the Sloan Digital Sky Survey and high-quality proper motions derived from multi-epoch positions extracted from the Guide Star Catalogue II database. In order to identify and characterise streams as relics of the Milky Way formation, we start with classifying, select, and study $2417$ subdwarfs with $\rm{[Fe/H] < -1.5}$ up to $3$ kpc away from the Sun as tracers of the local halo system. Then, through phase-space analysis, we find statistical evidence of five discrete kinematic overdensities among $67$ of the fastest-moving stars, and compare them to high-resolution N-body simulations of the interaction between a Milky-Way like galaxy and orbiting dwarf galaxies with four representative cases of merging histories. The observed overdensities can be interpreted as fossil substructures consisting of streamers torn from their progenitors, such progenitors appear to be satellites on prograde and retrograde orbits on different inclinations. In particular, of the five detected overdensities, two appear to be associated, yelding twenty-one additional main-sequence members, with the stream of Helmi et al. (1999) that our analysis confirms on a high inclination prograde orbit. The three newly identified kinematic groups could be associated with the retrograde streams detected by Dinescu (2002) and Kepley et al. (2007), whatever their origin, the progenitor(s) would be on retrograde orbit(s) and inclination(s) within the range $10^{\circ} \div 60^{\circ}$. Finally, we use our simulations to investigate the impact of observational errors and compare the current picture to the promising prospect of highly improved data expected from the Gaia mission.Comment: 16 pages, 10 figures, 6 Tables. Accepted for publication in The Astronomical Journa

Evidence of a large scale positive rotation-metallicity correlation in the Galactic thick disk

This study is based on high quality astrometric and spectroscopic data from the most recent releases by Gaia and APOGEE. We select $58\,882$ thin and thick disk red giants, in the Galactocentric (cylindrical) distance range $5 < R < 13$~kpc and within $|z| < 3$~kpc, for which full chemo-kinematical information is available. Radial chemical gradients, $\partial \rm{[M/H]} / \partial \rm{R}$, and rotational velocity-metallicity correlations, $\partial V_\phi / \partial \rm{[M/H]}$, are re-derived firmly uncovering that the thick disk velocity-metallicity correlation maintains its positiveness over the $8$~kpc range explored. This observational result is important as it sets experimental constraints on recent theoretical studies on the formation and evolution of the Milky Way disk and on cosmological models of Galaxy formation.Comment: Accepted for publication in Monthly Notices of the Royal Astronomical Societ

GPU-powered Simulation Methodologies for Biological Systems

The study of biological systems witnessed a pervasive cross-fertilization between experimental investigation and computational methods. This gave rise to the development of new methodologies, able to tackle the complexity of biological systems in a quantitative manner. Computer algorithms allow to faithfully reproduce the dynamics of the corresponding biological system, and, at the price of a large number of simulations, it is possible to extensively investigate the system functioning across a wide spectrum of natural conditions. To enable multiple analysis in parallel, using cheap, diffused and highly efficient multi-core devices we developed GPU-powered simulation algorithms for stochastic, deterministic and hybrid modeling approaches, so that also users with no knowledge of GPUs hardware and programming can easily access the computing power of graphics engines.Comment: In Proceedings Wivace 2013, arXiv:1309.712

Molecular analysis of sarcomeric and non-sarcomeric genes in patients with hypertrophic cardiomyopathy.

Background: Hypertrophic cardiomyopathy (HCM) is a common genetic heart disorder characterized by unexplained left ventricle hypertrophy associated with non-dilated ventricular chambers. Several genes encoding heart sarcomeric proteins have been associated to HCM, but a small proportion of HCM patients harbor alterations in other non-sarcomeric loci. The variable expression of HCM seems influenced by genetic modifier factors and new sequencing technologies are redefining the understanding of genotype–phenotype relationships, even if the interpretations of the numerous identified variants pose several challenges. Methods and results: We investigated 62 sarcomeric and non-sarcomeric genes in 41 HCM cases and in 3 HCM-related disorders patients. We employed an integrated approach that combines multiple tools for the prediction, annotation and visualization of functional variants. Genotype–phenotype correlations were carried out for inspecting the involvement of each gene in age onset and clinical variability of HCM. The 80% of the non-syndromic patients showed at least one rare non-synonymous variant (nsSNV) and among them, 58% carried alterations in sarcomeric loci, 14% in desmosomal and 7% in other non-sarcomeric ones without any sarcomere change. Statistical analyses revealed an inverse correlation between the number of nsSNVs and age at onset, and a relationship between the clinical variability and number and type of variants. Conclusions: Our results extend the mutational spectrum of HCM and contribute in defining the molecular pathogenesis and inheritance pattern(s) of this condition. Besides, we delineate a specific procedure for the identification of the most likely pathogenetic variants for a next generation sequencing approach embodied in a clinical context

Hardware design of LIF with Latency neuron model with memristive STDP synapses

In this paper, the hardware implementation of a neuromorphic system is presented. This system is composed of a Leaky Integrate-and-Fire with Latency (LIFL) neuron and a Spike-Timing Dependent Plasticity (STDP) synapse. LIFL neuron model allows to encode more information than the common Integrate-and-Fire models, typically considered for neuromorphic implementations. In our system LIFL neuron is implemented using CMOS circuits while memristor is used for the implementation of the STDP synapse. A description of the entire circuit is provided. Finally, the capabilities of the proposed architecture have been evaluated by simulating a motif composed of three neurons and two synapses. The simulation results confirm the validity of the proposed system and its suitability for the design of more complex spiking neural network

A multilevel theoretical study to disclose the binding mechanisms of gold(III) bipyridyl compounds as selective aquaglyceroporin inhibitors

Structural studies have paved the avenue to a deeper understanding of aquaporins (AQPs), small ancient proteins providing efficient transmembrane pathways for water, small uncharged solutes such as glycerol, and possibly gas molecules. Despite the numerous studies, their roles in health and disease remain to be fully disclosed. The recent discovery of AuIII complexes as potent and selective inhibitors of aquaglyceroporin isoforms paves the way to their possible therapeutic application. The binding of the selective human AQP3 inhibitor, the cationic complex [Au(bipy)Cl2]+ (Aubipy), to the protein channel has been investigated here by means of a multi-level theoretical workflow that includes QM, MD and QM/MM approaches. The hydroxo complex was identified as the prevalent form of Aubipy in physiological media and its binding to AQP3 studied by MD. Both non-covalent and coordinative Aubipy–AQP3 adducts were simulated to probe their role in the modulation of water channel functionality. The electronic structures of representative Aubipy–AQP3 adducts were then analysed to unveil the role played by the metal moiety in their stabilisation. This study spotlights the overall importance of three key aspects for AQP3 inhibition: 1) water speciation of the AuIII complex, 2) stability of non-covalent adducts and 3) conformational changes induced within the pore by the coordinative binding of AuIII. The obtained results are expected to orient future developments in the design of isoform-selective AuIII inhibitors

Effect of a thin superficial layer on the estimate of hemodynamic changes in a two-layer medium by time domain NIRS

In order to study hemodynamic changes involved in muscular metabolism by means of time domain fNIRS, we need to discriminate in the measured signal contributions coming from different depths. Muscles are, in fact, typically located under other tissues, e.g. skin and fat. In this paper, we study the possibility to exploit a previously proposed method for analyzing time-resolved fNIRS measurements in a two-layer structure with a thin superficial layer. This method is based on the calculation of the timedependent mean partial pathlengths. We validated it by simulating venous and arterial arm cuff occlusions and then applied it on in vivo measurements

Probe-hosted silicon photomultipliers for time-domain functional near-infrared spectrscopy: phantom and in vivo tests

We report the development of a compact probe for time-domain (TD) functional near-infrared spectroscopy (fNIRS) based on a fast silicon photomultiplier (SiPM) that can be put directly in contact with the sample without the need of optical fibers for light collection. We directly integrated an avalanche signal amplification stage close to the SiPM, thus reducing the size of the detection channel and optimizing the signal immunity to electromagnetic interferences. The whole detection electronics was placed in a plastic screw holder compatible with the electroencephalography standard cap for measurement on brain or with custom probe holders. The SiPM is inserted into a transparent and insulating resin to avoid the direct contact of the scalp with the 100-V bias voltage. The probe was integrated in an instrument for TD fNIRS spectroscopy. The system was characterized on tissue phantoms in terms of temporal resolution, responsivity, linearity, and capability to detect deep absorption changes. Preliminary in vivo tests on adult volunteers were performed to monitor hemodynamic changes in the arm during a cuff occlusion and in the brain cortex during a motor tas