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12 pags., 6 figs., 2 tabs. ; We investigate four-body nuclear reactions in stellar environments contributing to the creation of light nuclei, exemplified by Be9 and C12. The originally assumed process is radiative capture, where nuclear clusters combine into the excited final nucleus and photon emission populates the stable nuclear ground states. Instead, we consider nuclear four-body recombination reactions where a spectator nuclear particle replaces the photon. We first develop the elaborate formalism for both direct and sequential capture processes, where the decaying three-body resonance is formed without and with population of an intermediate two-body resonance, respectively. To facilitate both calculations and practical applications we parametrize the involved cross sections as done successfully in previous computations of reaction rates. We consider the lowest-lying nuclear states with their dominant contributions at low stellar temperatures. We calculate and compare reaction and production rates for different processes. The direct reaction mechanism dominates by many orders of magnitude at low temperature, where the sequential stepping stones are energetically too expensive to use. At somewhat higher temperatures these two different nuclear four-body mechanisms become comparable. Comparison to radiative three-body capture reveals already formally, but also numerically, that four-body nuclear recombination must dominate for sufficiently high nuclear densities. Numerical values are given for all these rates as a function of temperature and density. The relative importance is exhibited. ; This work has been partially supported by the Spanish Ministerio de Economía y Competitividad and European Union FEDER funds under Contract No. PGC2018-093636-B-I00.

6 pags., 3 figs., 1 tab. ; The structure and B(E1) transition strength of 19B are investigated in a 17B+n+n model, triggered by a recent experiment showing that 19B exhibits a well-pronounced two-neutron halo structure. Preliminary analysis of the experimental data was performed by employing contact n¿n interactions, which are known to underestimate the s-wave content in other halo nuclei, such as 11Li. In the present Rapid Communication, the three-body hyperspherical formalism with finite-range two-body interactions is used to describe 19B. In particular, two different finite-range n¿n interactions will be used as well as a simple central Gaussian potential whose range is progressively reduced. The purpose is to determine the main properties of the nucleus and investigate how they change when using contactlike n¿n potentials. Special attention is also paid to the dependence on the prescription used to account for three-body effects, i.e., a three-body force or a density-dependent n¿n potential. We have found that the three-body model plus finite-range potentials provide a description of 19B consistent with the experimental data. The results are essentially independent of the short-distance details of the two-body potentials, giving rise to a (s1/2)2 content of about 55%, clearly larger than the initial estimates. Very little dependence has been found as well on the prescription used for the three-body effects. The total computed B(E1) strength is compatible with the experimental result, although we slightly overestimate the data around the low-energy peak of the dB(E1)/d¿ distribution. Finally, we show that a reduction of the n¿n interaction range produces a significant reduction of the s-wave contribution, which then should be expected in calculations using contact interactions. ; This work has been partially supported by SID funds 2019 (Università degli Studi di Padova, Italy) under Project No. CASA_SID19_01, by the Spanish Ministry of Science, Innovation and University MCIU/AEI/FEDER,UE (Spain) under Contract No. PGC2018-093636-B-I00, and by the European Union's Horizon 2020 Research and Innovation Program under Grant Agreement No. 654002 (ENSAR2).

4 págs.; 3 figs.; 1 tab. ; PACS number (s): 25.60.2t, 21.45.1v, 21.60.Gx, 27.20.1n ; Momentum distributions of particles from nuclear breakup of fast three-body halos are calculated consistently, and applied to Li-11. The same two-body interactions between the three particles are used to calculate the ground state structure and the final state of the reaction processes. We reproduce the available momentum distributions from Li-11 fragmentation, together with the size and energy of Li-11, with a neutron-core relative state containing ap-state admixture of 20%-30%. The available fragmentation data strongly suggest an s state in Li-10 at about 50 keV and indicate a p state around 500 keV. ©1996 American Physical Society ; One of us (E.G.) acknowledges support from the European Union through the Human Capital and Mobility program Contract No. ERBCHBGCT930320 ; Peer Reviewed

Abstract Although we are far from a universally accepted pattern of impaired function at altitude, there is evidence indicating motor, perceptual, memory and behavioural deficits in adults. Even relatively low altitudes (2500 m) may delay reaction time, and impair motor function. Extreme altitude exposure (>5000 m) may result in more pronounced impairment that can persist after returning to the lowlands. Research into the effects of altitude exposure earlier in development is lacking by comparison. Un‐acclimatized children can suffer from acute mountain sickness, and, in native populations born at altitude, subtle cognitive and behavioural deficits suggest incomplete adaptation to hypoxia. The study of neurobehavioural functioning at altitude may provide important information about the effects of clinical hypoxia on the human brain and behavioural development.

AbstractLarge-scale coordinated efforts have been dedicated to understanding the global health and economic implications of the COVID-19 pandemic. Yet, the rapid spread of discrimination and xenophobia against specific populations has largely been neglected. Understanding public attitudes toward migration is essential to counter discrimination against immigrants and promote social cohesion. Traditional data sources to monitor public opinion are often limited, notably due to slow collection and release activities. New forms of data, particularly from social media, can help overcome these limitations. While some bias exists, social media data are produced at an unprecedented temporal frequency, geographical granularity, are collected globally and accessible in real-time. Drawing on a data set of 30.39 million tweets and natural language processing, this article aims to measure shifts in public sentiment opinion about migration during early stages of the COVID-19 pandemic in Germany, Italy, Spain, the United Kingdom, and the United States. Results show an increase of migration-related Tweets along with COVID-19 cases during national lockdowns in all five countries. Yet, we found no evidence of a significant increase in anti-immigration sentiment, as rises in the volume of negative messages are offset by comparable increases in positive messages. Additionally, we presented evidence of growing social polarization concerning migration, showing high concentrations of strongly positive and strongly negative sentiments.

As cities expand, human mobility has become a central focus of urban planning and policy making to make cities more inclusive and sustainable. Initiatives such as the "15-minutes city" have been put in place to shift the attention from monocentric city configurations to polycentric structures, increasing the availability and diversity of local urban amenities. Ultimately they expect to increase local walkability and increase mobility within residential areas. While we know how urban amenities influence human mobility at the city level, little is known about spatial variations in this relationship. Here, we use mobile phone, census, and volunteered geographical data to measure geographic variations in the relationship between origin-destination flows and local urban accessibility in Barcelona. Using a Negative Binomial Geographically Weighted Regression model, we show that, globally, people tend to visit neighborhoods with better access to education and retail. Locally, these and other features change in sign and magnitude through the different neighborhoods of the city in ways that are not explained by administrative boundaries, and that provide deeper insights regarding urban characteristics such as rental prices. In conclusion, our work suggests that the qualities of a 15-minutes city can be measured at scale, delivering actionable insights on the polycentric structure of cities, and how people use and access this structure. ; E.G-G., F.S-B., F.M.C. and P.R. were partly supported by the H2020 IoTwins project (Distributed Digital Twins for industrial SMEs: a big-data platform) funded by the EU under the call ICT-11-2018-2019, Grant Agreement No 857191. E.G-G. was partly funded by ANID Fondecyt de Iniciación 11180913. ; Peer Reviewed ; Postprint (published version)

In this paper, the Camp Nou stadium is used as a testbed for City Physiology, a theoretical framework for urban digital twins. With this case study, the modularity and adaptability of the framework, originally intended for city-scale simulations, are tested on a large facility venue. As a proof of concept, several statistical techniques and an agent-based simulation platform are coupled to simulate a crowd in the stadium, and a process of four steps is followed to build the case study. Both the conceptual (interdomain) and technical (domain specific) layers of the digital twin are defined and connected in a nonlinear process so that they represent the complexity of the object to be simulated. &e result obtained is a strategy to build a digital twin from the domain point of view, paving the way for more complex, more ambitious simulators ; This project has received funding from the European Union's Horizon 2020 Research and Innovation Programme under the IoTwins Project (Grant agreement no. 857191). I. Meta was partially funded by the Agencia Estatal de Investigación-Ministerio de Ciencia Innovación (AEI MICINN) and the European Social Fund (ESF) under the FPI program (scholarship no. PRE2019-090239). ; Peer Reviewed ; Postprint (published version)