Oscillatons revisited

In this paper, we study some interesting properties of a spherically symmetric oscillating soliton star made of a real time-dependent scalar field which is called an oscillaton. The known final configuration of an oscillaton consists of a stationary stage in which the scalar field and the metric coefficients oscillate in time if the scalar potential is quadratic. The differential equations that arise in the simplest approximation, that of coherent scalar oscillations, are presented for a quadratic scalar potential. This allows us to take a closer look at the interesting properties of these oscillating objects. The leading terms of the solutions considering a quartic and a cosh scalar potentials are worked in the so called stationary limit procedure. This procedure reveals the form in which oscillatons and boson stars may be related and useful information about oscillatons is obtained from the known results of boson stars. Oscillatons could compete with boson stars as interesting astrophysical objects, since they would be predicted by scalar field dark matter models.Comment: 10 pages REVTeX, 10 eps figures. Updated files to match version published in Classical and Quantum Gravit

Axisymmetric Stationary Solutions as Harmonic Maps

We present a method for generating exact solutions of Einstein equations in vacuum using harmonic maps, when the spacetime possesses two commutating Killing vectors. This method consists in writing the axisymmetric stationry Einstein equations in vacuum as a harmonic map which belongs to the group SL(2,R), and decomposing it in its harmonic "submaps". This method provides a natural classification of the solutions in classes (Weil's class, Lewis' class etc).Comment: 17 TeX pages, one table,( CINVESTAV- preprint 12/93

Spin-orbit coupling induced by a mass gradient

The existence of a spin-orbit coupling (SOC) induced by the gradient of the effective mass in low-dimensional heterostructures is revealed. In structurally asymmetric quasi-two-dimensional semiconductor heterostructures the presence of a mass gradient across the interfaces results in a SOC which competes with the SOC created by the electric field in the valence band. However, in graded quantum wells subjected to an external electric field, the mass-gradient induced SOC can be finite even when the electric field in the valence band vanishes.Comment: 4 pages, 2 figures, 1 tabl

Food system sustainability metrics: Policies, quantification, and the role of complexity sciences

The rise of global attention toward sustainability and sustainable development (SD) has provided increased incentives for research development and investment in these areas. Food systems are at the center of human needs and global population growth sustainability concerns. These drives and the need to provide quantified support for related investment projects led to the proliferation of sustainability metrics and frameworks. While questions about sustainability definition and measurement still abound, SD policy design and control increasingly need adequate quantified support instruments. This paper aims to address this need, contributing to a more consistent and integrated application of food system sustainability metrics and quantified management of the implemented solutions. After presenting the relationships between sustainability, resilience, and robustness and summarizing food system sustainability quantification developments so far, we expose complexity sciences’ potential contributions toward SD quantified evaluation, addressing prediction, intangibles, and uncertainty issues. Finding a paramount need to make sense and bring existing sustainability metrics in context for operational use, we conclude that the articulated application of multiple and independent modeling approaches at the micro, meso, and macro levels can better help the development of food SD policies and implemented solution quantified management, with due regard to confidence levels of the results obtained.info:eu-repo/semantics/publishedVersio

Measured Quantum Dynamics of a Trapped Ion

The measurement process is taken into account in the dynamics of trapped ions prepared in nonclassical motional states. The induced decoherence is shown to manifest itself both in the inhibition of the internal population dynamics and in a damping of the vibrational motion without classical counterpart. Quantitative comparison with present experimental capabilities is discussed, leading to a proposal for the verification of the predicted effects.Comment: 5 Pages, no figures; Plain REVTeX; to be published in the 1st May issue of Phys. Rev. A, Rap. Commun. (1997

The impact of the Covid-19 pandemic on the execution of educational measures in the community

This study is part of the JUST COVID 19 project (Universidade Católica Portuguesa), in partnership with the YO&JUST project (Universidade NOVA de Lisboa) and its overall objective is to understand the impact of the COVID 19 pandemic on the execution of educational measures in the community. Although this phenomenon is recent, international studies have already highlighted its impact on justice systems and juvenile delinquency (Gordon, Klose, & Lyttle Storrod, 2020; Buchanan, Castro, Kushner, & Krohn, 2020; McCarthy, Homel, Ogilvie & Allard, 2021). However, at national level, there is a lack of research on this topic, thus making this study an added value to understand this reality and subsequently bring contributions that safeguard the interests of children and young people. In order to achieve the defined objectives, interviews were carried out with seven professionals working in the Portuguese juvenile justice system, particularly in the metropolitan areas of Porto and Lisbon and in Alto Alentejo. The Annual Statistical Reports of the Direção Geral de Reinserção e Serviços Prisionais from 2015 to 2020 and the Reports from February, May and December 2021 of the same entity were also used. The analysis of the data allowed evidencing several impacts arising from the pandemic in the execution of tutelary educational measures in the community.info:eu-repo/semantics/publishedVersio

Galactic Collapse of Scalar Field Dark Matter

We present a scenario for galaxy formation based on the hypothesis of scalar field dark matter. We interpret galaxy formation through the collapse of a scalar field fluctuation. We find that a cosh potential for the self-interaction of the scalar field provides a reasonable scenario for galactic formation, which is in agreement with cosmological observations and phenomenological studies in galaxies.Comment: 4 pages, 3 figue

COVID-19 pandemic and the use of illicit substances in young people with delinquent behaviors

This study is part of the JUST COVID-19 (UCP) and YO&JUST (CICS-NOVA) projects, aiming to understand the impact of the covid-19 pandemic on the use of illicit substances by young people with delinquent behaviours. Early onset of substance use in adolescence has been associated with increased delinquency and subsequent criminality, specifically including violent crime, and being at particularly high risk of serious problems later in life (Gordon et al., 2004). As the pandemic progressed, containment measures were implemented. Social distancing to decrease interaction between individuals (Duarte, 2020), the closure of schools and other places that provided crowding of the population (Schmidt, 2020), as well as the general isolation caused in young people various stressors such as fear of being infected, distress, loneliness, anxiety and depression (Scalia et al., 2020). These variables may have caused changes in the contexts and patterns of illicit substance use. To understand such changes several professionals who work with young people with deviant behaviours were interviewed. In this poster, we present the study and its main results.info:eu-repo/semantics/publishedVersio

Test Case 4: dual band transmit-array

In this report a numerical solution for the dual band transmit-array challegenge proposed for the WORKSHOP EM-ISAE 2018 (test case nº 4) is presented. The numerical results are compared with the measurements of the corresponding prototype (see Figure 1). More details about the design and fabrication processes of the dual band TA can be found in [1]. To perform the corresponding full-wave simulations was quite challenging, mainly due to the large volume occupied by the antenna (comprising the feed and lens) and the fine subwavelength details of the unit cells that populate the TA. In fact, we did not had at that time sufficient memory to perform the full-wave simulation of the complete antenna (feed+lens). In this workshop we detailed the developed approach used to conduct the full-wave analysis of the TA within our available computational resources.info:eu-repo/semantics/acceptedVersio