Degeneracy between warm and coupled cold dark matter: A clarifying note

Wei et al [PRD 88, 043510 (2013)] have proposed the existence of a cosmological degeneracy between warm dark matter (WDM), modified gravity and coupled cold dark matter (CDM) cosmologies at both the background expansion and the growth of density perturbation levels, i.e., corresponding cosmological data would not be able to differentiate such scenarios. Here, we will focus on the specific indistinguishability between a warm dark matter plus cosmological constant ($\Lambda$) and coupled scalar field-CDM scenarios. Although the statement of Wei et al is true for very specific conditions we present a more complete discussion on this issue and show in more detail that these models are indeed distinguishable. We show that the degeneracy breaks down since coupled models leave a specific signature in the redshift space distortion data which is absent in the uncoupled warm dark matter cosmologies. Furthermore, we complement our claim by providing the reasons which suggest that even at nonlinear level a breaking of such apparent equivalence is also expected.Comment: 6 pages, 1 Figure; revised version, section IV extended and enriched with further discussion, title altered, typos corrected and new references added. Version published in PR

Alterations in brain connectivity due to plasticity and synaptic delay

Brain plasticity refers to brain's ability to change neuronal connections, as a result of environmental stimuli, new experiences, or damage. In this work, we study the effects of the synaptic delay on both the coupling strengths and synchronisation in a neuronal network with synaptic plasticity. We build a network of Hodgkin-Huxley neurons, where the plasticity is given by the Hebbian rules. We verify that without time delay the excitatory synapses became stronger from the high frequency to low frequency neurons and the inhibitory synapses increases in the opposite way, when the delay is increased the network presents a non-trivial topology. Regarding the synchronisation, only for small values of the synaptic delay this phenomenon is observed

Optimized Multimode Interference Fiber Based Refractometer in A Reflective Interrogation Scheme

A fiber based refractometer in a reflective interrogation scheme is investigated and optimized. A thin gold film was deposited on the tip of a coreless fiber section, which is spliced with a single mode fiber. The coreless fiber is a multimode waveguide, and the observed effects are due to multimode interference. To investigate and optimize the structure, the multimode part of the sensor is built with 3 different lengths: 58 mm, 29 mm and 17 mm. We use a broadband light source ranging from 1475 nm to 1650 nm and we test the sensors with liquids of varying refractive indices, from 1.333 to 1.438. Our results show that for a fixed wavelength, the sensor sensitivity is independent of the multimode fiber length, but we observed a sensitivity increase of approximately 0.7 nm/RIU for a one-nanometer increase in wavelength

Free software: A Social, Educational, Collaborative and Open to Human Inventiveness Network.

Technological advances are present in different segments of society and, in education, social transformations are consolidated as an important element for technical, human and political development, for that, it is necessary to dialogue with technologies that converge to the same look, in this sense. , Free Software represents an advance in this perception of collaborative movement, acting as a link to a scenario that represents the sum of all knowledge in the teaching versus learning relationship. This model used in Free Software, which prioritizes the subject in the construction of knowledge, constitutes an important ally for the consolidation of the elements present in the spaces of education, whether due to the cultural diversity resulting from the existing relations between the production communities, whether by the amount of existing technological resources in the different areas of knowledge and for the different levels of education. The graphic representation, supported by the theory of networks, about the existing relationships between the different areas of knowledge and the various levels of education on the quantity of software cataloged in the database of the Blog Software Livre na Educação (BSLE) of the Federal University of Rio Grande do Sul (UFRGS), although not exhausted by the present study, presents itself as an important analysis tool for discussions that dialogue with this theme, and which aims, in addition to bringing the reader closer to the theme, a computational model on the elements present in these relationships, contributing to the analysis of potentialities and specific needs in each area, especially in the educational context

Generation of higher derivatives operators and electromagnetic wave propagation in a Lorentz-violation scenario

We study the perturbative generation of higher-derivative operators as corrections to the photon effective action, which are originated from a Lorentz violation background. Such corrections are obtained, at one-loop order, through the proper-time method, using the zeta function regularization. We focus over the lowest order corrections and investigate their influence in the propagation of electromagnetic waves through the vacuum, in the presence of a strong, constant magnetic field. This is a setting of experimental relevance, since it bases active efforts to measure non linear electromagnetic effects. After surprising cancellations of Lorentz violating corrections to the Maxwell's equation, we show that no effects of the kind of Lorentz violation we consider can be detected in such a context.Comment: v2: 13 pages, no figures, section IV considerably rewritten, main results unchanged and are now obtained in a simpler way. To appear in PL

Renal Oncocytoma in Pregnancy. An Unusual Presentation of Secondary Hypertension

Introdução: O oncocitoma renal representa 5-7% das neoplasias primárias do rim, é diagnosticado em doentes assintomáticos e caracteriza-se por um comportamento benigno, sem invasão dos tecidos adjacentes ou metastização. O seu diagnóstico no decurso da gravidez é raro, havendo poucos casos descritos na literatura. Caso clínico: Os autores apresentam o caso de uma nulípara de 32 anos com hipertensão arterial de difícil controlo diagnosticada às sete semanas gestacionais com internamento às 24 semanas por quadro de hipertensão crónica agravada com pré-eclâmpsia sobreposta, edema agudo do pulmão e instabilidade hemodinâmica com necessidade de suporte ventilatório mecânico, restrição do crescimento fetal e morte fetal. O estudo etiológico do quadro hipertensivo efectuado no período pós-parto permitiu demonstrar a existência de um tumor renal-oncocitoma. Conclusão: O comportamento clínico do oncocitoma renal permanece mal caracterizado durante a gravidez, podendo associar-se, apesar do seu comportamento teoricamente benigno, a um desfecho materno e fetal adverso. É fundamental excluir uma possível causa secundária nos quadros hipertensivos de difícil controlo

O extrativismo da castanha-do-brasil na região do Baixo Rio Branco, RR.

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Coaches’ migration: decisions and perceived importance of international experience

The migration of coaches is a topic that has seen increasing research interest in recent years. Discussions are evolving around the factors driving coaches' migration, their experiences, and perceptions held by other sports stakeholders. This study aimed to explore the decision-making processes of coaches regarding migration and their views on the phenomenon. A total of 68 coaches, both with and without international experience, participated in the study. Data collection involved an online survey comprisingclosed-ended questions. For data analysis, we employed a One-Way ANOVA to draw comparisons across independent variables. Interestingly, coaches with international experience have been more frequently approached with offers than their counterparts without such experience. Nevertheless, the majority of the coaches did not perceive foreign coaches as essential to sports development. Coaches with international backgrounds expressed a belief that native coaches should exclusively coach their national teams. Overall, coaches did not highly value international placements or experience. These unexpected findings have significant implications for coach training programs globally. The results are further explored in the context of the expertise required to work in a globalised sports setting and interact with stakeholders from diverse cultural backgrounds

Electric properties of granitic rocks

The objective of this work is to clarify the role of water content on the charge trans- port mechanisms of different granitic rocks. The mineralogical content of the rocks will also be taken into account. From the electrical point of view these materials are rather insulating porous media where charge injection creates different phenomena like build-up charges, space charge limited currents, surface effects and other behav- iors that resemble much a variety of oxides, like AlO