Phase transitions between Reissner-Nordstrom and dilatonic black holes in 4D AdS spacetime

We study Einstein-Maxwell-dilaton gravity models in four-dimensional anti-de Sitter (AdS) spacetime which admit the Reissner-Nordstrom (RN) black hole solution. We show that below a critical temperature the AdS-RN solution becomes unstable against scalar perturbations and the gravitational system undergoes a phase transition. We show using numerical calculations that the new phase is a charged dilatonic black hole. Using the AdS/CFT correspondence we discuss the phase transition in the dual field theory both for non-vanishing temperatures and in the extremal limit. The extremal solution has a Lifshitz scaling symmetry. We discuss the optical conductivity in the new dual phase and find interesting behavior at low frequencies where it shows a "Drude peak". The resistivity varies with temperature in a non-monotonic way and displays a minimum at low temperatures which is reminiscent of the celebrated Kondo effect.Comment: 19 pages - v2: minor corrections and additional references -v3: Figs.5 changed and additional comments. Version accepted in JHE

Effect of space conditions on neuronal plasticity and connectivity

Looking for opportunities to explore new frontiers and developing new technologies have always been in the nature of mankind. In 1957, the first rocket in space opened a new era for space traveling towards other planets. Concomitantly, a wide range of concerns related to human health risks that could occur during spaceflight was raised. Up to now, a large number of experiments has been performed to determine the biological effects of space conditions on human health, in order to develop appropriate countermeasures. However, extensive investigations still need to be performed before considering long-term spaceflight towards other planets such as Mars. Since the first human space flight, it has been observed that in weightlessness conditions, equilibrium sense organs can send misleading inputs to the central nervous system which is forced to develop new strategies and adapt to adequately translate these messages. Furthermore, cosmic radiations are known to induce oxidative stress as well as genomic damages. In this thesis, we studied concomitant microgravity and radiation exposures as models for space conditions and developed various methods to analyse their specific and combined effects on in vitro neuronal network models. In vitro primary neuronal network cultures were established and exposed to simulated space conditions to investigate neuronal network remodelling (plasticity and connectivity) as well as genomic damage/repair dynamics. This work was performed to address questions on neuronal network disorders occurring during spaceflights and, in the future, to develop strategies against these effects

Impact of multiple modes on the black-hole superradiant instability

Ultralight bosonic fields in the mass range $\sim (10^{-20}-10^{-11})\,{\rm eV}$ can trigger a superradiant instability that extracts energy and angular momentum from an astrophysical black hole with mass $M\sim(5,10^{10})M_\odot$, forming a nonspherical, rotating condensate around it. So far, most studies of the evolution and end-state of the instability have been limited to initial data containing only the fastest growing superradiant mode. By studying the evolution of multimode data in a quasi-adiabatic approximation, we show that the dynamics is much richer and depend strongly on the energy of the seed, on the relative amplitude between modes, and on the gravitational coupling. If the seed energy is a few percent of the black-hole mass, a black hole surrounded by a mixture of superradiant and nonsuperradiant modes with comparable amplitudes might not undergo a superradiant unstable phase, depending on the value of the boson mass. If the seed energy is smaller, as in the case of an instability triggered by quantum fluctuations, the effect of nonsuperradiant modes is negligible. We discuss the implications of these findings for current constraints on ultralight fields with electromagnetic and gravitational-wave observations.Comment: 21 pages, 12 figures; matches version accepted in PR

IFHNFS: fast indexing information in mobile devices

Abstract To track movements of objects and people we need to use expensive technologies and complex softwares. Usually these softwares need lots of memory. There are many examples of objects and people of which would be useful to know the precise locations. Something sent via pony express, position of buses in the city, friends' locations, and so on. Our purpose is to use connectivity of smartphone to share position via gps by using only a filesystem created ad hoc without databases or user space programs. IFHNFS is based on Hixosfs and NFS (Linux kernel). Indexing the most relevant data directly in the fs structure makes the exchange of data Faster and, via NFS, potentially available whenever and whenever. Ad-hoc solutions for Android have been developed in real contexts. The system have been tested on a network of Android OS devices that share data with a Linux server

Superradiant instabilities by accretion disks in scalar-tensor theories

We study the superradiant instability in scalar-tensor theories of gravitation, where matter outside a black hole provides an effective mass to the scalar degree of freedom of the gravitational sector. We discuss this effect for arbitrarily spinning black holes and for realistic models of truncated thin and thick accretion disks (where the perturbation equations are nonseparable), paying particular attention to the role of hot coronal flows in the vicinity of the black hole. The system qualitatively resembles the phenomenology of plasma-driven superradiant instabilities in General Relativity. Nevertheless, we show that the obstacles hampering the efficiency of plasma-driven superradiant instabilities in General Relativity can be circumvented in scalar-tensor theories. We find a wide range of parameter space where superradiant instabilities can be triggered in realistic scenarios, and discuss the constraints on scalar-tensor theories imposed by this effect. In particular, we argue that the existence of highly spinning accreting black holes is in tension with some scalar-tensor alternatives to the dark energy, e.g. symmetron models with screening.Comment: 13 pages, 6 figure

Medicine Thefts And Their Prevention: Current Approach In Italy And Future Perspectives:

In recent years, medicine thefts have become a European challenge. In Italy, the number of thefts, from hospitals, has increased exponentially since 2011. The major drivers were the introduction of life-saving expensive medicines, the price differentials between countries and the different reimbursement regimes adopted in the European Union. This situation resulted in the AIFA (Italian Medicines Agency) Counterfeiting Prevention Unit setting up a number of preventive strategies that have minimized and in some cases eradicated the problem. In this review, we briefly describe trends and impacts of medicine thefts in Italy, the 'Herceptin Case', a major criminal effort that has been dismantled, and some of the preliminary results of PADLOck (Progetto di Adeguamento Dei Livelli di sicurezza delle farmacie Ospedaliere contro il rischio di furti e definizione di standard tecnici), a study aimed at evaluating the safety of hospital pharmacists and made sure that preventive and corrective measures against medicine thefts are put in place. The implementation of some of the tools developed by AIFA is under evaluation and/or implementation by other European Authorities, leading to a more effective approach in tackling one of the most relevant challenges in access to medicines in the European Union

An FPGA platform for real-time simulation of spiking neuronal networks

In the last years, the idea to dynamically interface biological neurons with artificial ones has become more and more urgent. The reason is essentially due to the design of innovative neuroprostheses where biological cell assemblies of the brain can be substituted by artificial ones. For closed-loop experiments with biological neuronal networks interfaced with in silico modeled networks, several technological challenges need to be faced, from the low-level interfacing between the living tissue and the computational model to the implementation of the latter in a suitable form for real-time processing. Field programmable gate arrays (FPGAs) can improve flexibility when simple neuronal models are required, obtaining good accuracy, real-time performance, and the possibility to create a hybrid system without any custom hardware, just programming the hardware to achieve the required functionality. In this paper, this possibility is explored presenting a modular and efficient FPGA design of an in silico spiking neural network exploiting the Izhikevich model. The proposed system, prototypically implemented on a Xilinx Virtex 6 device, is able to simulate a fully connected network counting up to 1,440 neurons, in real-time, at a sampling rate of 10 kHz, which is reasonable for small to medium scale extra-cellular closed-loop experiments

Non-conventional apoptotic response to ionising radiation mediated by N-methyl D-aspartate receptors in immature neuronal cells

During cortical development, N-methyl D-aspartate (NMDA) receptors are highly involved in neuronal maturation and synapse establishment. Their implication in the phenomenon of excitotoxicity has been extensively described in several neurodegenerative diseases due to the permissive entry of Ca2+ ions and massive accumulation in the intracellular compartment, which is highly toxic to cells. Ionising radiation is also a source of stress to the cells, particularly immature neurons. Their capacity to induce cell death has been described for various cell types either by directly damaging the DNA or indirectly through the generation of reactive oxygen species responsible for the activation of a battery of stress response effectors leading in certain cases, to cell death. In this study, in order to determine whether a link exists between NMDA receptors-mediated excitotoxicity and radiation-induced cell death, we evaluated radiation-induced cell death in vitro and in vivo in maturing neurons during the fetal period. Cell death induction was assessed by TUNEL, caspase-3 activity and DNA ladder assays, with or without the administration of dizocilpine (MK-801), a non-competitive NMDA receptor antagonist which blocks neuronal Ca2+ influx. To further investigate the possible involvement of Ca2+-dependent enzyme activation, known to occur at high Ca2+ concentrations, we examined the protective effect of a calpain inhibitor on cell death induced by radiation. Doses ranging from 0.2 to 0.6 Gy of X-rays elicited a clear apoptotic response that was prevented by the injection of dizocilpine (MK-801) or calpain inhibitor. These data demonstrate the involvement of NMDA receptors in radiation-induced neuronal death by the activation of downstream effectors, including calpain-related pathways. An increased apoptotic process elicited by radiation, occurring independently of the normal developmental scheme, may eliminate post-mitotic but immature neuronal cells and deeply impair the establishment of the neuronal network, which in the case of cortical development is critical for cognitive capacities

Diagnostic Value of the Early Heart-to-Mediastinum Count Ratio in Cardiac 123I-mIBG imaging for Parkinson's Disease

Early diagnosis of Parkinson's disease (PD) is of primary importance. The delayed (3-4 h after injection) Iodine-123-Metaiodobenzylguanidine (123I-mIBG) scintigraphy has been proven to be effective in early differential diagnosis for Lewy body disease. But early imaging (15-30 min after injection) has only been marginally studied for its possible diagnostic role. In this prospective study a thresholdfor the early Heart-to-Mediastinum (H/M) count ratio has been investigated, obtaining a diagnostic accuracy analogous to conventional, delayed imaging

Combined exposure to simulated microgravity and acute or chronic radiation reduces neuronal network integrity and survival

During orbital or interplanetary space flights, astronauts are exposed to cosmic radiations and microgravity. However, most earth-based studies on the potential health risks of space conditions have investigated the effects of these two conditions separately. This study aimed at assessing the combined effect of radiation exposure and microgravity on neuronal morphology and survival in vitro. In particular, we investigated the effects of simulated microgravity after acute (X-rays) or during chronic (Californium-252) exposure to ionizing radiation using mouse mature neuron cultures. Acute exposure to low (0.1 Gy) doses of Xrays caused a delay in neurite outgrowth and a reduction in soma size, while only the high dose impaired neuronal survival. Of interest, the strongest effect on neuronal morphology and survival was evident in cells exposed to microgravity and in particular in cells exposed to both microgravity and radiation. Removal of neurons from simulated microgravity for a period of 24 h was not sufficient to recover neurite length, whereas the soma size showed a clear re-adaptation to normal ground conditions. Genome-wide gene expression analysis confirmed a modulation of genes involved in neurite extension, cell survival and synaptic communication, suggesting that these changes might be responsible for the observed morphological effects. In general, the observed synergistic changes in neuronal network integrity and cell survival induced by simulated space conditions might help to better evaluate the astronaut's health risks and underline the importance of investigating the central nervous system and long-term cognition during and after a space flight