The luminosity--volume test for cosmological Fast Radio Bursts

We perform the luminosity--volume test, also known as $\langle V/V_{MAX}\rangle$, to Fast Radio Bursts (FRBs). We compare the 23 FRBs, recently discovered by ASKAP, with 20 of the FRBs found by Parkes. These samples have different flux limits and correspond to different explored volumes. We assume that their dispersion measure indicates their redshift and apply the appropriate cosmological corrections to the spectrum and rate in order to compute the $\langle V/V_{MAX}\rangle$ for the ASKAP and Parkes samples. For a radio spectrum of FRBs $F_\nu \propto \nu^{-1.6}$, we find $\langle V/V_{MAX}\rangle=0.66\pm 0.05$ for the ASKAP sample, that includes FRBs up to $z=0.7$, and 0.52$\pm 0.04$ for Parkes, that extends up to $z=2.1$. The ASKAP value suggests that the population of FRB progenitors evolves faster than the star formation rate, while the Parkes value is consistent with it. Even a delayed (as a power law or gaussian) star formation rate cannot reproduce the $\langle V/V_{MAX}\rangle$ of both samples. If FRBs do not evolve in luminosity, the $\langle V/V_{MAX}\rangle$ values of ASKAP and Parkes sample are consistent with a population of progenitors whose density strongly evolves with redshift as $\sim z^{2.8}$ up to $z \sim 0.7$. We discuss possible scenarios accounting for our results.Comment: 10 pages, 5 figures, 3 tables, accepted by A&A on 2019/04/0

A risk analysis methodology for the use of crowd models during the Covid-19 pandemic

Pandemics such as Covid-19 have posed a set of questions concerning safe space usage given the risk of virus transmission in confined and open spaces. In this context, this report presents a risk analysis methodology for the use of crowd modelling tools as an aid to assess safety in confined and open spaces. Crowd models can be used to investigate people movement in the built environment, thus they have a great potential for the performance of proximity analysis. The report presented here addresses first the psychological and physical aspects linked to physical distancing (also called social distancing). Given the limited current knowledge on human behaviour and space usage during pandemics, the changes needed in crowd modelling tools to appropriately represent people movement are listed. This includes issues associated with modifications of the fundamental relationships between the key people movement variables (speed/flow vs density), and issues linked with interactions between pedestrians (e.g. collision avoidance, queuing mechanisms, route choice). Suggestions for new crowd modelling outputs are provided in order to enhance their use during pandemics. In addition, practical solutions concerning space usage are presented in light of the assessment of human safety through a risk evaluation based on proximity analysis and/or exposure assessment. This is deemed to help identifying design and management solutions to decrease the risk of virus transmission

Power Management Circuits for Low-Power RF Energy Harvesters

The paper describes the design and implementation of power management circuits for RF energy harvesters suitable for integration in wireless sensor nodes. In particular, we report the power management circuits used to provide the voltage supply of an integrated temperature sensor with analog-to-digital converter. A DC-DC boost converter is used to transfer efficiently the energy harvested from a generic radio-frequency rectifier into a charge reservoir, whereas a linear regulator scales the voltage supply to a suitable value for a sensing and conversion circuit. Implemented in a 65 nm CMOS technology, the power management system achieves a measured overall efficiency of 20%, with an available power of 4.5 μW at the DC-DC converter input. The system can sustain a temperature measurement rate of one sample/s with an RF input power of −28 dBm, making it compatible with the power levels available in generic outdoor environments

Origins of postmodern impegno: ethical and political commitment in the works of Gianni Celati

This research investigates the role of Gianni Celati in the development of postmodern forms of impegno in contemporary Italy. It examines Celati’s entire works, as a writer, literary critic, translator and film-maker, from the perspective of his ethical and political commitment. This study analyses Celati’s choices in terms of language, content and style to see in what way his idea of literature engages with society and proposes Celati’s ethical and political commitment as a determining aspect to be considered when studying his oeuvre. In addition, it investigates what technical and theoretical structures used by Celati represent a relevant inheritance for the following generations of writers who have expressed and conceptualized forms of impegno in present-day Italy. It offers three case studies of authors who are directly linked to Celati and develop new forms of impegno, partly following Celati’s ideas, partly distancing themselves from that model. Gianni Celati (1937) is usually not considered an engaged writer and he himself would probably refuse this definition. Nevertheless, an ethical commitment constantly precedes and shapes his idea of literature and arts (Schwarz Lausten 2009). Celati’s works permanently engage with society and, it is argued, participate actively in revolutionary moments in Italian post-war history. This research draws on the more recent theories on postmodern ‘impegno’, which assign to Italian culture the role of ‘testing-ground’ of new forms of ethical and political commitment. The study draws on the theoretical framework outlined by Burns (2001) and Antonello-Mussgnug (2009). The end of structured and ideological thinking and the demise of Gramsci’s ‘organic intellectual’ do not mean the end of socio-political commitment, which instead arises now in a fragmentary way, refusing dogmatic statements. Celati has a crucial role in the passage between post-war ‘impegno’ and new forms of ethical and political commitment. Celati has never embraced an all-inclusive ideological view: he has rather differentiated his political commitment through an ethical way of thinking about the role of literature. The characteristics of Celati’s engagement anticipated what happened in Italy during the mature postmodern phase, namely what scholars have called ‘Postmodern Impegno’, addressing issues that have been emphasized by subsequent generations of ‘new engaged’ writers

The use of multi-zone modelling for tunnel fire risk analysis

Tunnel fire risk analysis are a useful tool to ensure adequate safety levels in tunnels. This report presents the work conducted to integrate a multi-zone modelling approach into a fire risk assessment tool, called ARTU. This work was performed to improve its fire modelling predictive capabilities compared to the currently adopted 1D fire modelling representation. This is deemed to allow for the use of multi-scale modelling, i.e., to select among different modelling approaches in relation to the scenarios under consideration. The multi-zone model integrated within ARTU is based on an existing tool, i.e., the MZ Fire model developed for large spaces which has been updated and adapted for tunnel environments. The integration of MZ Fire model into ARTU involved a set of developments needed specifically for tunnel fire scenarios (e.g. considering tunnel gradient, tunnel section representations, customization of outputs for use in a tunnel fire risk assessment tool, etc.). Those new features are here presented along with a sensitivity analysis looking at zone size. Benchmarking of the results produced is performed through comparison with data from the 2006 BeNeLux tunnel experiments and the 2015 Runehamar experiments. The multi-zone model results were also compared against results from the Fire Dynamics Simulator (FDS) for a set of tunnel configurations

A Low-Power Sigma-Delta Modulator for Healthcare and Medical Diagnostic Applications

This paper presents a switched-capacitor Sigma-Delta modulator designed in 90-nm CMOS technology, operating at 1.2-V supply voltage. The modulator targets healthcare and medical diagnostic applications where the readout of small-bandwidth signals is required. The design of the proposed A/D converter was optimized to achieve the minimum power consumption and area. A remarkable performance improvement is obtained through the integration of a low-noise amplifier with modified Miller compensation and rail-to-rail output stage. The manuscript also presents a set of design equations, from the small-signal analysis of the amplifier, for an easy design of the modulator in different technology nodes. The Sigma-Delta converter achieves a measured 96-dB dynamic range, over a 250-Hz signal bandwidth, with an oversampling ratio of 500. The power consumption is 30 μW, with a silicon area of 0.39 mm²

Analyzing the Galactic Pulsar Distribution with Machine Learning

We explore the possibility of inferring the properties of the Galactic population of neutron stars through machine learning. In particular, in this paper we focus on their dynamical characteristics and show that an artificial neural network is able to estimate with high accuracy the parameters that control the current positions of a mock population of pulsars. For this purpose, we implement a simplified population-synthesis framework (where selection biases are neglected at this stage) and concentrate on the natal kick-velocity distribution and the distribution of birth distances from the Galactic plane. By varying these and evolving the pulsar trajectories in time, we generate a series of simulations that are used to train and validate a suitably structured convolutional neural network. We demonstrate that our network is able to recover the parameters governing the distribution of kick velocity and Galactic height with a mean relative error of about 10−2. We discuss the limitations of our idealized approach and study a toy problem to introduce selection effects in a phenomenological way by incorporating the observed proper motions of 216 isolated pulsars. Our analysis highlights that by increasing the sample of pulsars with accurate proper-motion measurements by a factor of ∼10, one of the future breakthroughs of the Square Kilometre Array, we might succeed in constraining the birth spatial and kick-velocity distribution of the neutron stars in the Milky Way with high precision through machine learning.M.R., V.G., A.G., and N.R. acknowledge support from the H2020 ERC Consolidator Grant “MAGNESIA”’ under grant agreement No. 817661 (PI: Rea), and grants SGR2017-1383 and PGC2018-095512-B-I00. J.A.P. acknowledges support by the Generalitat Valenciana grant PROMETEO/2019/071 and by AEI grant PGC2018-095984-B-I00. This work has also been partially supported by the PHAROS COST Action (CA16214)

Epineurial window is more efficient in attracting axons than simple coaptation in a sutureless (cyanoacrylate-bound) model of end-to-side nerve repair in the rat upper limb: Functional and morphometric evidences and review of the literature

End-to-side nerve coaptation brings regenerating axons from the donor to the recipient nerve. Several techniques have been used to perform coaptation: microsurgical sutures with and without opening a window into the epi(peri)neurial connective tissue; among these, window techniques have been proven more effective in inducing axonal regeneration. The authors developed a sutureless model of end-to-side coaptation in the rat upper limb. In 19 adult Wistar rats, the median and the ulnar nerves of the left arm were approached from the axillary region, the median nerve transected and the proximal stump sutured to the pectoral muscle to prevent regeneration. Animals were then randomly divided in two experimental groups (7 animals each, 5 animals acting as control): Group 1: the distal stump of the transected median nerve was fixed to the ulnar nerve by applying cyanoacrylate solution; Group 2: a small epineurial window was opened into the epineurium of the ulnar nerve, caring to avoid damage to the nerve fibres; the distal stump of the transected median nerve was then fixed to the ulnar nerve by applying cyanoacrylate solution. The grasping test for functional evaluation was repeated every 10-11 weeks starting from week-15, up to the sacrifice (week 36). At week 36, the animals were sacrificed and the regenerated nerves harvested and processed for morphological investigations (high-resolution light microscopy as well as stereological and morphometrical analysis). This study shows that a) cyanoacrylate in end-to-side coaptation produces scarless axon regeneration without toxic effects; b) axonal regeneration and myelination occur even without opening an epineurial window, but c) the window is related to a larger number of regenerating fibres, especially myelinated and mature, and better functional outcomes