GRB970228 as a prototype for short GRBs with afterglow

GRB970228 is analyzed as a prototype to understand the relative role of short GRBs and their associated afterglows, recently observed by Swift and HETE-II. Detailed theoretical computation of the GRB970228 light curves in selected energy bands are presented and compared with observational BeppoSAX data.Comment: 2 pages, 1 figure, to appear in the proceedings of "Swift and GRBs", Venice, 2006, Il Nuovo Cimento, in pres

Theoretical interpretation of GRB060124: preliminary results

We show the preliminary results of the application of our "fireshell" model to GRB060124. This source is very peculiar because it is the first event for which both the prompt and the afterglow emission were observed simultaneously by the three Swift instruments: BAT (15-350 keV), XRT (0.2-10 keV) and UVOT (170-650 nm), due to the presence of a precursor ~ 570 s before the main burst. We analyze GRB060124 within our "canonical" GRB scenario, identifying the precursor with the P-GRB and the prompt emission with the afterglow peak emission. In this way we reproduce correctly the energetics of both these two components. We reproduce also the observed time delay between the precursor (P-GRB) and the main burst. The effect of such a time delay in our model will be discussed.Comment: 6 pages, 2 figures, to appear on the Proceedings of the Eleventh Marcel Grossmann Meeting, Berlin (Germany), July 200

The Effect of the External Driving Forces Modelling on the Calculated Building Energy Need Through the Use of Dynamic Simulation

An extensive validation of the EN ISO 52016-1 hourly method is still missing. In this paper, the main modelling assumptions related to the envelope outdoor surface heat balance are analysed. The variation in the accuracy of a detailed dynamic model is assessed when the EN ISO 52016-1 assumptions are applied to the model. To guarantee a general validity of the outcomes, two case studies in three Italian cities are considered. The results showed that the assumptions related to the definition of the convective and radiative heat transfer lead to nonnegligible variation in the energy needs

Heritability of human "directed" functional connectome

IntroductionThe functional connectivity patterns in the brain are highly heritable; however, it is unclear how genetic factors influence the directionality of such "information flows." Studying the "directionality" of the brain functional connectivity and assessing how heritability modulates it can improve our understanding of the human connectome. MethodsHere, we investigated the heritability of "directed" functional connections using a state-space formulation of Granger causality (GC), in conjunction with blind deconvolution methods accounting for local variability in the hemodynamic response function. Such GC implementation is ideal to explore the directionality of functional interactions across a large number of networks. Resting-state functional magnetic resonance imaging data were drawn from the Human Connectome Project (total n = 898 participants). To add robustness to our findings, the dataset was randomly split into a "discovery" and a "replication" sample (each with n = 449 participants). The two cohorts were carefully matched in terms of demographic variables and other confounding factors (e.g., education). The effect of shared environment was also modeled. ResultsThe parieto- and prefronto-cerebellar, parieto-prefrontal, and posterior-cingulate to hippocampus connections showed the highest and most replicable heritability effects with little influence by shared environment. In contrast, shared environmental factors significantly affected the visuo-parietal and sensory-motor directed connectivity. ConclusionWe suggest a robust role of heritability in influencing the directed connectivity of some cortico-subcortical circuits implicated in cognition. Further studies, for example using task-based fMRI and GC, are warranted to confirm the asymmetric effects of genetic factors on the functional connectivity within cognitive networks and their role in supporting executive functions and learning

Validation of the simplified heat conduction model of EN ISO 52016-1

The issue of improving the building energy efficiency led to the development of calculation methods for the building energy performance assessment. To overcome the low accessibility to detailed input data, the recently introduced EN ISO 52016-1 hourly method is based on assumptions and simplifications chosen to allow a sufficient accuracy in the outcomes with a low amount of input data. Among these assumptions, a simplified mass distribution in the envelope components is considered. In the present work, the hypothesis of the simplified heat conduction model introduced by the EN ISO 52016-1 technical standard and an improved solution provided by its Italian National Annex were evaluated. In particular, the accuracy in the prediction of the internal surface temperature was assessed in comparison with a detailed finite difference conduction algorithm. The validation was performed for 5 opaque component test cases, covering a wide range of areal heat capacity values, by considering both internal and external thermal constraints (e.g. variation of the air temperature). For the structures and boundary conditions considered, results reveal that the standard algorithm allows to predict the internal surface temperatures with a valuable level of accuracy compared to the finite difference algorithm

The Blackholic energy and the canonical Gamma-Ray Burst

We outline the main results of our GRB model, based on the three interpretation paradigms we proposed in July 2001, comparing and contrasting them with the ones in the current literature. Thanks to the observations by Swift and by VLT, this analysis points to a "canonical GRB" originating from markedly different astrophysical scenarios. The communality is that they are all emitted in the formation of a black hole with small or null angular momentum. The following sequence appears to be canonical: the vacuum polarization process creating an optically thick self accelerating electron-positron plasma; the engulfment of baryonic mass during the plasma expansion; the adiabatic expansion of the optically thick "fireshell" up to the transparency; the interaction of the remaining accelerated baryons with the interstellar medium (ISM). This leads to the canonical GRB composed of a proper GRB (P-GRB), emitted at the moment of transparency, followed by an extended afterglow. The parameters are the plasma total energy, the fireshell baryon loading and the ISM filamentary distribution around the source. In the limit of no baryon loading the total energy is radiated in the P-GRB. In this limit, the canonical GRBs explain as well the short GRBs.Comment: 163 pages, 89 figures, to appear on the "Proceedings of the XIIth Brazilian School of Cosmology and Gravitation", M. Novello, S.E. Perez-Bergliaffa (editors), AIP, in pres

Short and canonical GRBs

Within the "fireshell" model for the Gamma-Ray Bursts (GRBs) we define a "canonical GRB" light curve with two sharply different components: the Proper-GRB (P-GRB), emitted when the optically thick fireshell of electron-positron plasma originating the phenomenon reaches transparency, and the afterglow, emitted due to the collision between the remaining optically thin fireshell and the CircumBurst Medium (CBM). We outline our "canonical GRB" scenario, with a special emphasis on the discrimination between "genuine" and "fake" short GRBs.Comment: 4 pages, 3 figures, in the Proceedings of the "Gamma Ray Bursts 2007" meeting, November 5-9, 2007, Santa Fe, New Mexico, US

Theoretical interpretation of "long" and "short" GRBs

Within the "fireshell" model we define a "canonical GRB" light curve with two sharply different components: the Proper-GRB (P-GRB), emitted when the optically thick fireshell of electron-positron plasma originating the phenomenon reaches transparency, and the afterglow, emitted due to the collision between the remaining optically thin fireshell and the CircumBurst Medium (CBM). We here present the consequences of such a scenario on the theoretical interpretation of the nature of "long" and "short" GRBs.Comment: 3 pages, 1 figure, to appear on the Proceedings of the Eleventh Marcel Grossmann Meeting, Berlin (Germany), July 200

The Blackholic energy and the canonical Gamma-Ray Burst IV: the "long", "genuine short" and "fake - disguised short" GRBs

(Shortened) [...] After recalling the basic features of the "fireshell model", we emphasize the following novel results: 1) the interpretation of the X-ray flares in GRB afterglows as due to the interaction of the optically thin fireshell with isolated clouds in the CircumBurst Medium (CBM); 2) an interpretation as "fake - disguised" short GRBs of the GRBs belonging to the class identified by Norris & Bonnell [...] consistent with an origin from the final coalescence of a binary system in the halo of their host galaxies with particularly low CBM density [...]; 3) the first attempt to study a genuine short GRB with the analysis of GRB 050509B, that reveals indeed still an open question; 4) the interpretation of the GRB-SN association in the case of GRB 060218 via the "induced gravitational collapse" process; 5) a first attempt to understand the nature of the "Amati relation", a phenomenological correlation between the isotropic-equivalent radiated energy of the prompt emission E_{iso} with the cosmological rest-frame \nu F_{\nu} spectrum peak energy E_{p,i}. In addition, recent progress on the thermalization of the electron-positron plasma close to their formation phase, as well as the structure of the electrodynamics of Kerr-Newman Black Holes are presented. An outlook for possible explanation of high-energy phenomena in GRBs to be expected from the AGILE and the Fermi satellites are discussed. As an example of high energy process, the work by Enrico Fermi dealing with ultrarelativistic collisions is examined. It is clear that all the GRB physics points to the existence of overcritical electrodynamical fields. In this sense we present some progresses on a unified approach to heavy nuclei and neutron stars cores, which leads to the existence of overcritical fields under the neutron star crust.Comment: 68 pages, 50 figures, in the Proceedings of the XIII Brazilian School on Cosmology and Gravitation, M. Novello, S.E. Perez-Bergliaffa, editor

A Parsimonious Granger Causality Formulation for Capturing Arbitrarily Long Multivariate Associations.

High-frequency neuroelectric signals like electroencephalography (EEG) or magnetoencephalography (MEG) provide a unique opportunity to infer causal relationships between local activity of brain areas. While causal inference is commonly performed through classical Granger causality (GC) based on multivariate autoregressive models, this method may encounter important limitations (e.g., data paucity) in the case of high dimensional data from densely connected systems like the brain. Additionally, physiological signals often present long-range dependencies which commonly require high autoregressive model orders/number of parameters. We present a generalization of autoregressive models for GC estimation based on Wiener-Volterra decompositions with Laguerre polynomials as basis functions. In this basis, the introduction of only one additional global parameter allows to capture arbitrary long dependencies without increasing model order, hence retaining model simplicity, linearity and ease of parameters estimation. We validate our method in synthetic data generated from families of complex, densely connected networks and demonstrate superior performance as compared to classical GC. Additionally, we apply our framework to studying the directed human brain connectome through MEG data from 89 subjects drawn from the Human Connectome Project (HCP) database, showing that it is able to reproduce current knowledge as well as to uncover previously unknown directed influences between cortical and limbic brain regions.MR