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

Comportamento da erva-sal (Atriplex nummularia) irrigada com água de alta salinidade.

Com o objetivo de avaliar o seu comportamento - em termos de rendimento e de retirada de sais dosolo, quando irrigada com água de alta salinidade - a erva-sal (Atriplex nummularia) foi cultivada, durante um ano, nos campos da estação Experimental da Embrapa Semi-Árido. As plantas foram irrigadas com efluentes do tanque de criação de Tilápia (Oriochromis sp.) e com água de poço, de concentração salina média de 10, 11 dS m-1. Cada planta recebeu 225 litros de água por semana, aplicada de uma só vez, durante 43 semanas. A salinidade média do perfil era de 0,40 dS m-1 antes de iniciar a irrigação das plantas. Depois da colheita das plantas, a salinidade do perfil de solo foi se 4,97 dS m-1. A produtividade da erva-sal foi de 18,92 t ha -1 ano de matéria seca. A erva-sal apresentou um grande potencial de extração de sais do perfil de solo. Neste experimento a planta conseguiu extrair 3,0 t ha -1 ano. Mais estudos são necessários para avaliar o comportamento da planta com lâminas d' águas maiores e menores à usada neste trabalho

Economic and natural effects of nitrate pollution of agricultural origin, in particular the aquatic enviroment

The whole area of Hungary is the gathering ground of our principal rivers (Duna, Tisza) and some bigger lakes, like Balaton, Fertő lake and Velencei lake. The water isn’t only staff of life; it is one of the most sensitive biotope of world. We suppose to protect our aquatic environment from environmental pollution as such nitrate pollution or eutrophication. Trough agricultural production the nutrient rate increases in water. The weeds begin to pullulate, they are taking up more oxygen from the water, they are necrosis, the depth of warp increases faster so the eutrophication drowns on, and the nitrate rate of rivers increases

Hate speech dynamics against African descent, Roma and LGBTQ+ communities in Portugal

This paper introduces FIGHT, a dataset containing 63,450 tweets, posted before and after the official declaration of Covid-19 as a pandemic by online users in Portugal. This resource aims at contributing to the analysis of online hate speech targeting the most representative minorities in Portugal, namely the African descent and the Roma communities, and the LGBTQ+ community, the most commonly reported target of hate speech in social media at the European context. We present the methods for collecting the data, and provide insightful statistics on the distribution of tweets included in FIGHT, considering both the temporal and spatial dimensions. We also analyze the availability over time of tweets targeting the aforementioned communities, distinguishing public, private, and deleted tweets. We believe this study will contribute to better understand the dynamics of online hate speech in Portugal, particularly in adverse contexts, such as a pandemic outbreak, allowing the development of more informed and accurate hate speech resources for Portuguese.info:eu-repo/semantics/publishedVersio

Entropic Entanglement Criteria for Continuous Variables

We derive several entanglement criteria for bipartite continuous variable quantum systems based on the Shannon entropy. These criteria are more sensitive than those involving only second-order moments, and are equivalent to well-known variance product tests in the case of Gaussian states. Furthermore, they involve only a pair of quadrature measurements, and will thus should prove extremely useful the experimental identification of entanglement.Comment: 4 pages, 2 figure

A simulation Approach to Assess Partners Selected for a Collaborative Network

[EN] Manufacturing enterprises are increasingly more aware of the importance of establishing collaborative relationships with their network partners, due to the advantages associated to collaboration. Nevertheless, the participation in a collaborative network (CN) comes with associated challenges, namely the need to reduce the potential for conflicts among partners. A CN consists of heterogeneous partners, each one defining its own objectives and activating its own strategies. In this context, the ability to quickly identify partners with aligned strategies is crucial for smooth operation of the CN. The main aim of this paper is to address the partners' selection problem in the context of Virtual organizations Breeding Environments (VBE) that facilitate and enable the creation of Virtual Organisations (VO), as one type of CN. In a first stage, the sets of enterprises, characterised by having the required competencies to create the VO, are identified among different potential candidates within the VBE. In a second stage, the strategies alignment approach, based on the system dynamics simulation method, is used for the partners' selection process, identifying the best set of enterprises. In this paper, the final stage of partners' selection process is addressed by obtaining the degree of alignment of the business strategies formulated by each set of enterprises. In the light of this, a system dynamics-simulation model, in AnyLogic, is presented to obtain the set of enterprises that have higher levels of alignment in its strategies. The proposed system dynamics-simulation model is applied to a case in the building industry, to deal with the partners' selection problem in a VBE with the aim of forming a stable and sustainable VO.This work has been funded in part by Programa Val i+d para investigadores en formación (ACIF 2012) and by the Uninova–Center of Technology and Systems and the Portuguese FCT-PEST program UID/EEA/00066/2013.Andres, B.; Poler, R.; Camarinha-Matos, L.; Afsarmanesh, H. (2017). A simulation Approach to Assess Partners Selected for a Collaborative Network. International Journal of Simulation Modelling. 16(3):399-411. https://doi.org/10.2507/IJSIMM16(3)3.382S39941116