650 research outputs found
Low latency search for gravitational waves from black-hole-neutron-star binaries in coincidence with short gamma-ray bursts
No full textWe propose a procedure to be used in the search for gravitational waves from black-hole-neutron-star coalescing binaries, in coincidence with short gamma-ray bursts. It is based on two recently proposed semianalytic fits, one reproducing the mass of the remnant disk surrounding the black hole which forms after the merging as a function of some binary parameters, the second relating the neutron star compactness, i.e., the ratio of mass and radius, with its tidal deformability. Using a Fisher matrix analysis and the two fits, we assign a probability that the emitted gravitational signal is associated to the formation of an accreting disk massive enough to supply the energy needed to power a short gamma-ray burst. This information can be used in low-latency data analysis to restrict the parameter space searching for gravitational wave signals in coincidence with short gamma-ray bursts and to gain information on the dynamics of the coalescing system and on the internal structure of the components. In addition, when the binary parameters are measured with high accuracy, it will be possible to use this information to trigger the search for off-axis gamma-ray burst afterglows
Involvement of chemical perception in control of reproduction in Octopus vulgaris
No full textAmong invertebrates reproductive strategies are much more diversified than vertebrates. Recently we have found in Octopus vulgaris that olfactory sensory neurons (OSNs) express several peptides involved in reproduction and feed intake such as GnRH and NPY (Polese et al., 2015). We suggest at central level, a context-dependent modulation of olfactory epithelial activity by olfactory lobe making the octopus female more sensitive to a sex related stimulus rather than a food one during reproduction. In Octopus vulgaris mainly two lobes, subpedunculate lobe and olfactory lobe (supraoesophageal mass), and a neuroendocrine gland (the optic gland) are the neuroanatomical areas involved in the central control of reproduction. In those, several neuropeptides, NMDA receptors, an oestrogen receptor, oct-ER work in synergy to modulate optic gland activity, in turn involved in the production of a gonadotropin still unknown. The olfactory lobe plays a crucial role in mediating sexual behavior, functioning as an integrative centre in which converges chemosensory information intercepted by olfactory organ via the OSNs. At peripheral level the control of reproduction is mediated by fusiform ganglion that innervates the reproductive tracts in both male and female. Neuropeptides, sex steroid hormones, optic gland hormone and a recently discovered chemoattractant factor octo-SAP are the peripheral physiological players responsible of reproductive behavior. Despite the advanced state of knowledge about the mechanisms that regulate reproduction in Octopus vulgaris and cephalopods in general, many questions remain unanswered
Rana complex come organismo sentinella di effetti degenerativi del DNA in aree degradate della regione Campania
No full textSolving the relativistic inverse stellar problem through gravitational waves observation of binary neutron stars
No full textThe LIGO/Virgo Collaboration has recently announced the direct detection of gravitational waves emitted in the coalescence of a neutron star binary. This discovery allows, for the first time, to set new constraints on the behavior of matter at supranuclear density, complementary with those coming from astrophysical observations in the electromagnetic band. In this paper we demonstrate the feasibility of using gravitational signals to solve the relativistic inverse stellar problem, i.e., to reconstruct the parameters of the equation of state (EoS) from measurements of the stellar mass and tidal Love number. We perform Bayesian inference of mock data, based on different models of the star internal composition, modeled through piecewise polytropes. Our analysis shows that the detection of a small number of sources by a network of advanced interferometers would allow to put accurate bounds on the EoS parameters, and to perform a model selection among the realistic equations of state proposed in the literature
Constraining the equation of state of nuclear matter with gravitational wave observations: Tidal deformability and tidal disruption
No full textWe study how to extract information on the neutron star equation of state from the gravitational wave signal emitted during the coalescence of a binary system composed of two neutron stars or a neutron star and a black hole. We use post-Newtonian templates which include the tidal deformability parameter and, when tidal disruption occurs before merger, a frequency cutoff. Assuming that this signal is detected by Advanced LIGO/Virgo or the Einstein Telescope, we evaluate the uncertainties on these parameters using different data-analysis strategies based on the Fisher matrix approach and on recently obtained analytical fits of the relevant quantities. We find that the tidal deformability is more effective than the stellar compactness to discriminate among different possible equations of state. © 2013 American Physical Society
The impact of agro-pastoral abandonment on the Rock Partridge Alectoris graeca in the Apennines
No full textHuman depopulation of rural mountain areas and the consequent abandonment of tradi- tional land management are among the greatest driving forces behind changes in moun- tain ecosystems in Western Europe. Tree and shrub encroachment lead to an increase in landscape matrix uniformity and habitat fragmentation. For some animal species, this represents an unusual case of habitat loss caused by secondary succession. The animal species associated with this agro-pastoral habitat may suffer from decreased connectivity as a consequence. The Rock Partridge Alectoris graeca is a species endemic to European mountains that represents a model for investigating the impact of habitat loss. We com- pared the habitat suitability of the Apennine Rock Partridge prior to abandonment of traditional agro-pastoral activities by aerial photography with the current landscape, in order to investigate the effect of secondary succession on the distribution and viability of the species. We assessed the historical distribution (c. 1900–1950) by quantifying anec- dotal evidence from interviews, and the current distribution (2005) from survey data. We applied ecological niche factor analysis and connectivity approaches to evaluate change in habitat suitability over this time scale. Moreover, to quantify landscape connec- tivity, we evaluated the relative importance of each patch in the two periods. Results indicated that to maintain a viable population in the Apennines, the species requires an ensemble of ecological conditions considerably different from the current situation. We observed a drastic decrease in connectivity as a result of a reduction in numbers and size of high suitability patches. This is most probably the primary cause of the current decline of the Rock Partridge population in the Apennine
Testing gravity with quasi-periodic oscillations from accreting black holes: the case of the Einstein-Dilaton-Gauss-Bonnet theory
No full textQuasi-periodic oscillations (QPOs) observed in the X-ray flux emitted by accreting black holes are associated with phenomena occurring near the horizon. Future very large area X-ray instruments will be able to measure QPO frequencies with very high precision, thus probing this strong-field region. Using the relativistic precession model, we show the way in which QPO frequencies could be used to test general relativity (GR) against those alternative theories of gravity which predict deviations from the classical theory in the strong-field and high-curvature regimes. We consider one of the best-motivated high-curvature corrections to GR, namely, the Einstein–Dilaton– Gauss–Bonnet theory, and show that a detection of QPOs with the expected sensitivity of the proposed ESA M- class mission LOFT would set the most stringent constraints on the parameter space of this theory
Tidal interaction in compact binaries: A post-Newtonian affine framework
No full textWe develop a semianalytical approach, based on the post-Newtonian expansion and on the affine approximation, to model the tidal deformation of neutron stars in the coalescence of black hole-neutron star or neutron star-neutron star binaries. Our equations describe, in a unified framework, both the system orbital evolution, and the neutron star deformations. These are driven by the tidal tensor, which we expand at 1/c(3) post-Newtonian order, including spin terms. We test the theoretical framework by simulating black hole-neutron star coalescence up to the onset of mass shedding, which we determine by comparing the shape of the star with the Roche lobe. We validate our approach by comparing our results with those of fully relativistic, numerical simulations
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