Multidimensional integration through Markovian sampling under steered function morphing: a physical guise from statistical mechanics

We present a computational strategy for the evaluation of multidimensional integrals on hyper-rectangles based on Markovian stochastic exploration of the integration domain while the integrand is being morphed by starting from an initial appropriate profile. Thanks to an abstract reformulation of Jarzynski's equality applied in stochastic thermodynamics to evaluate the free-energy profiles along selected reaction coordinates via non-equilibrium transformations, it is possible to cast the original integral into the exponential average of the distribution of the pseudo-work (that we may term "computational work") involved in doing the function morphing, which is straightforwardly solved. Several tests illustrate the basic implementation of the idea, and show its performance in terms of computational time, accuracy and precision. The formulation for integrand functions with zeros and possible sign changes is also presented. It will be stressed that our usage of Jarzynski's equality shares similarities with a practice already known in statistics as Annealed Importance Sampling (AIS), when applied to computation of the normalizing constants of distributions. In a sense, here we dress the AIS with its "physical" counterpart borrowed from statistical mechanics.Comment: 3 figures Supplementary Material (pdf file named "JEMDI_SI.pdf"

Attracting subspaces in a hyper-spherical representation of autonomous dynamical systems

In this work, we focus on the possibility to recast the ordinary differential equations (ODEs) governing the evolution of deterministic autonomous dynamical systems (conservative or damped and generally non-linear) into a parameter-free universal format. We term such a representation \u201chyper-spherical\u201d since the new variables are a \u201cradial\u201d norm having physical units of inverse-of-time and a normalized \u201cstate vector\u201d with (possibly complex-valued) dimensionless components. Here we prove that while the system evolves in its physical space, the mirrored evolution in the hyper-spherical space is such that the state vector moves monotonically towards fixed \u201cattracting subspaces\u201d (one at a time). Correspondingly, the physical space can be split into \u201cattractiveness regions.\u201d We present the general concepts and provide an example of how such a transformation of ODEs can be achieved for a class of mechanical-like systems where the physical variables are a set of configurational degrees of freedom and the associated velocities in a phase-space representation. A one-dimensional case model (motion in a bi-stable potential) is adopted to illustrate the procedure

Targeting Brutons Tyrosine Kinase in Chronic Lymphocytic Leukemia at the Crossroad between Intrinsic and Extrinsic Pro-survival Signals

Chemo immunotherapies for chronic lymphocytic leukemia (CLL) showed a positive impact on clinical outcome, but many patients relapsed or become refractory to the available treatments. The main goal of the researchers in CLL is the identification of specific targets in order to develop new therapeutic strategies to cure the disease. The B cell receptor-signalling pathway is necessary for survival of malignant B cells and its related molecules recently become new targets for therapy. Moreover, leukemic microenvironment delivers survival signals to neoplastic cells also overcoming the apoptotic effect induced by traditional drugs. In this context, the investigation of Bruton\u2019s tyrosine kinase (Btk) is useful in: i) dissecting CLL pathogenesis; ii) finding new therapeutic approaches striking simultaneously intrinsic as well as extrinsic pro-survival signals in CLL. This paper will review these main topics

A Low-Computational-Cost Strategy to Localize Points in the Slow Manifold Proximity for Isothermal Chemical Kinetics

Dimensionality reduction for the modeling of reacting chemical systems can represent a fundamental achievement both for a clear understanding of the complex mechanisms under study and also for the practical calculation of quantities of interest. To tackle the problem, different approaches have been proposed in the literature. Among them, particular attention has been devoted to the exploitation of the so-called slow manifolds (SMs). These are lower dimensional hypersurfaces where the slow part of the evolution takes place. In this study, we present a low-computational-cost algorithm (based on a previously developed theoretical framework) for the localization of candidate points in the proximity of the SM. A parallel implementation (called DRIMAK) of such an approach has been developed, and the source code is made freely available. We tested the performance of the code on two model schemes for hydrogen combustion, being able to localize points that fall very close to the perceived SM with limited computational effort. The method can provide starting points for other more accurate but computationally demanding strategies; this can be a great help especially when no information about the SM is available a priori, and very many species are involved in the reaction mechanism

Relativistic plasmas in AGN jets - From synchrotron radiation to γ\gamma-ray emission

Relativistic jets of plasma are a key ingredient of many types of Active Galactic Nuclei (AGN). Today we know that AGNs are powered by the accretion of inter stellar material into the gravitational field of a Super Massive Black Hole and that this process can release as much power as a whole galaxy, like the Milky Way, from a region that is comparable to the Solar System in size. Depending on the properties of the central energy source, a large fraction of this power can be involved in the acceleration of magnetized plasmas at relativistic speeds, to form large scale jets. The presence of jets affects the spectrum of AGNs through the emission of synchrotron radiation and Inverse Compton scattering of low energy photons, thus leading to a prominent non-thermal spectrum, some times extending from radio frequencies all the way up to $\gamma$-ray energies. Here we review some characteristic processes of radiation emission in AGN jets, which lead to the emission of photons in the radio, optical, X-ray and $\gamma$-ray bands, and we present the results of a spectroscopic campaign of optical counterparts. We discuss our observations and their connection with $\gamma$-ray properties in a scenario that traces the role of relativistic jets in different classes of AGNs, detected both in the local as well as in the remote Universe.Comment: 11 pages, 5 figures (3 in color), proceedings of the XXVIII School on Physics of Ionized Gases (SPIG), accepted for publication on the European Journal of Physics

UM ESTUDO DAS NEGAÇÕES DE PEDRO A PARTIR DA EXEGESE DE JOHANNES BEUTLER

Este artigo se propõe a fazer um estudo exegético das negações de Pedro relatada no Evangelho de João, à luz das contribuições do exegeta alemão Johannes Beutler. Predito por Jesus, Pedro irá negá-lo publicamente. Estando no pátio do Sumo Sacerdote Caifás, o discípulo é questionado sobre sua pertença ao grupo daqueles que seguiam Jesus de mais de perto. Pedro responde negativamente às três vezes em que é inquerido. Para o Evangelista João, a negação de Pedro é uma falta de testemunho de quem é Jesus. A tríplice negação se configura, então, como não somente uma fraqueza do discípulo, mas o aniquilamento de sua personalidade como escolhido por Jesus. Aos poucos a voz de Pedro desaparece para dar lugar apenas a voz do galo que canta encerrando o trecho das negações. O artigo é divido em três partes: a primeira negação; inquérito de Jesus diante do Sumo Sacerdote; e a segunda e terceira negação, que no Evangelho de João é descrito continuamente

Sistema software per la stima della posa di oggetti industriali da dati tridimensionali

Lo scopo del presente lavoro è sviluppare un algoritmo per individuare la posa di oggetti in point cloud tridimensionali. La posa 6DOF viene individuata utilizzando un algoritmo per il riconoscimento di oggetti basato su PCL (Point Cloud Library). La soluzione proposta per il riconoscimento di oggetti si basa su correspondences grouping, utilizzando una versione della GHT estesa allo spazio 3d. L'algoritmo proposto è stato confrontato con una soluzione che utilizza, clustering e registrazioneope

Modeling the Extended narrow line Region in the era of Integral Field surveys

The Extended Narrow Line Region (ENLR) of Active Galactic Nuclei (AGN) is a region of highly ionized gas with conical or bi-conical shape, extending from the Narrow Line Region (~ 100 pc) up to 15-20 kpc with the apexes pointing towards the nucleus. At the moment ~ 50 galaxies have been found showing evidence of ENLR, the vast majority of which are nearby Seyfert galaxies. The presence of these cones is interpreted in the framework of the Unified Model of AGN thatpredicts an anisotropic radiation field escaping from the nucleus, collimated by a dusty torus. The strong non-thermal radiation produced by the accretion disk seems indeed to be the main responsible of the ionization in the ENLR, although the contribution of shocks cannot always be neglected. The ionized gas however does not reside entirely inside the cones. There is evidence of several Seyfert galaxies (e.g. NGC 4151, Mrk 3, NGC 3393) showing low-ionization lines emission, identifiable in BPT diagnostic diagrams as LINERs emission, located in the outskirts of the cones or even in the cross-cone region. It is argued that these spatial variation of the ionization in the ENLR may be a new channel in the study of the collimation by the torus and could provide valuable information on the torus structure (e.g. clumpiness, edge features). Moreover, recent advances in integral field spectroscopy and the start of the first integral field survey could provide an unprecedented advantage in a more thorough characterization of this phenomenon. The theoretical study of ionized gas in AGN is mainly carried out through photo-ionization models realized with dedicated codes. The radiative transfer, ionization and chemistry calculations are solved numerically due to the complexity of the problem. The state of the art of these models still relies on an ad hoc single-zone or two-zone approach, able to reproduce the gas spectral features in detail, however not suited to study spatial effects in the ENLR. The aim of this work is to explore a new method to realize photo-ionization models of ENLR, taking into account both a cloud-based distributions of gas and the effects of the torus structure on the collimation of the nuclear radiation and on the ionization of gas inside and outside the cones. For the first time the models will be bi-dimensional in order to provide a useful tool to be compared with integral field data. To achieve this goal we developed a python code able to perform a procedural generation of the gas distribution in different regions of space, i.e. the cloud parameters as their position, dimension and mass are randomly drawn from a probability distribution determined by the user. This multi-cloud approach is intended to avoid the simple assumption typical of traditional photo-ionization models and at the same time to reproduce the observation with a more realistic ansatz on the distribution of gas. The user can, for instance, generate clouds of gas in the galactic disk and ionize them with a chosen Spectral Energy Distribution (SED). To collimate the radiation we included a simple torus model, either clumpy, smooth or composite. The code interfaces with Cloudy, the photo-ionization code, through the pyCloudy libraries, and it is able to define a set of models, write the input files and, after the calculations are over, read and plot the results

High resolution spectroscopy of the extended narrow-line region of IC 5063 and NGC 7212

We studied the properties of the gas of the extended narrow line region (ENLR) of two Seyfert 2 galaxies: IC 5063 and NGC 7212. We analysed high resolution spectra to investigate how the main properties of this region depend on the gas velocity. We divided the emission lines in velocity bins and we calculated several line ratios. Diagnostic diagrams and SUMA composite models (photo-ionization + shocks), show that in both galaxies there might be evidence of shocks significantly contributing in the gas ionization at high |V|, even though photo-ionization from the active nucleus remains the main ionization mechanism. In IC 5063 the ionization parameter depends on V and its trend might be explained assuming an hollow bi-conical shape for the ENLR, with one of the edges aligned with the galaxy disk. On the other hand, NGC 7212 does not show any kind of dependence. The models show that solar O/H relative abundances reproduce the observed spectra in all the analysed regions. They also revealed an high fragmentation of the gas clouds, suggesting that the complex kinematics observed in these two objects might be caused by interaction between the ISM and high velocity components, such as jets.Comment: 29 pages, 32 figures, accepted for publication in MNRA

Models of emission line profiles and spectral energy distributions to characterize the multi-frequency properties of active galactic nuclei

The spectra of Active Galactic Nuclei (AGNs) are often characterized by a wealth of emission lines with different profiles and intensity ratios that led to a complicated classification. Their electro-magnetic radiation spans more than 10 orders of magnitude in frequency. In spite of the differences between various classes, the origin of their activity is attributed to a combination of emitting components, surrounding an accreting Super Massive Black Hole, in the so called Unified Model. Currently, the execution of sky surveys, with instruments operating at various frequencies, provides the possibility to detect and to investigate the properties of AGNs on very large statistical samples. Thanks to the spectroscopic surveys that allow investigation of many objects, we have the opportunity to place new constraints on the nature and evolution of AGNs. In this contribution we present the results obtained by working on multi-frequency data and we discuss their relations with the available optical spectra. We compare our findings with the AGN Unified Model predictions, and we present a revised technique to select AGNs of different types from other line emitting objects. We discuss the multi-frequency properties in terms of the innermost structures of the sources.Comment: 11 pages, 4 figures. Proceedings of the XI Serbian Conference on Spectral Line Shapes in Astrophysics. Accepted for publication on Atom