Investigation of the existence of hybrid stars using Nambu-Jona-Lasinio models

We investigate the hadron-quark phase transition inside neutron stars and obtain mass-radius relations for hybrid stars. The equation of state for the quark phase using the standard NJL model is too soft leading to an unstable star and suggesting a modification of the NJL model by introducing a momentum cutoff dependent on the chemical potential. However, even in this approach, the instability remains. In order to remedy the instability we suggest the introduction of a vector coupling in the NJL model, which makes the EoS stiffer, reducing the instability. We conclude that the possible existence of quark matter inside the stars require high densities, leading to very compact stars.Comment: 4 pages, 2 figures; prepared for IV International Workshop on Astronomy and Relativistic Astrophysics (IWARA 2009), Maresias, 4-8 Oct 200

NUTRIÇÃO ARTIFICIAL NO DOENTE CRÍTICO

Introdução: O suporte nutricional tem papel importan- te no tratamento dos doentes internados em Unidades de Cuidados Intensivos (UCI). O objetivo deste trabalho foi avaliar a carga calórica fornecida aos doentes críticos, con- siderando o impacto da carga calórica “secundária” (não nutricional) e a teoria da “Subnutrição permissiva”. Obje- tivos: Avaliar a carga calórica fornecida aos doentes inter- nados em Unidades de Cuidados Intensivos. Material e métodos: Estudo transversal analítico realizado em 6 dife- rentes Unidades de Cuidados Intensivos em doentes inter- nados mais de 5 dias. Resultados: 153 doentes, idade 58,18 ± 18,47 anos, sendo do foro médico (22,88%), cirúrgico (21,56%), neurocirúrgico (28,76%) e trauma (26,80%). Internados durante 14,54 ± 9,05 dias, com SOFA de 6,95 ± 3.23 e IMC de 24,57 ± 3,84. A mortalidade foi de 32,03%. Foram fornecidos 12,3 ± 8,4 kcal/kg/dia, com evolução gradativa nos 10 primeiros dias. A carga calórica secundária decresceu, apresentando impacto no valor calórico global somente até ao 2o dia de internamento. Os doentes do foro médico atingiram mais precocemente os objetivos nutricio- nais. A carga calórica secundária teve maior impacto nos pacientes cirúrgicos. Numa fase imediata e intermediária os doentes receberam um aporte calórico significativamente superior ao modelo de Wilmore, enquanto que na fase final o aporte foi significativamente inferior. Discussão: A sub- nutrição encontrada revelou-se diferente do conceito de subnutrição permissiva de Wilmore, provavelmente devido à desvalorização do peso, do bom estado nutricional na admissão, ou à própria gravidade desses doentes, colocan- do a terapia nutricional em segundo plano. Conclusão: Este estudo vem realçar a dificuldade que existe em fornecer um suporte nutricional adequado aos doentes internados em Unidades de Cuidados Intensivos

Stability of pace and turn parameters of elite long-distance swimmers

This study aimed to assess the stability of the performance, pace and turn parameters of elite long-distance male swimmers during an 800 m freestyle race. The sample was composed by 38 male swimmers, participating in the 800 m event at the 2016 LEN European Aquatic Championships (long course meter). The performance, and a set of pace and turn parameters were analyzed. A customized software was used to perform each race analysis. Swimmers spent 64.05 ± 0.50% and 35.95 ± 0.49% of the final race time in the clean swim and turns, respectively. In the pace parameters, the clean swim was the only one that did not differ between the first and second half of the race (1.63 ± 0.05 vs 1.62 ± 0.05 m·s−1), and in the turn parameters, the water break distance was also similar (5.13 ± 1.17 vs 5.06 ± 0.98 m). A significant and moderate-strong variation was verified for the performance (total race lap effect: p < 0.001, η2 = 0.62), and a significant and moderate variation for the pace parameters (total race: p < 0.001, 0.15 ≤ η2 ≤ 0.33), and for the turn parameters (total race: p < 0.01, 0.15 ≤ η2 ≤ 0.33). Present data (pace and turn variation) shows that elite long-distance male swimmers do not maintain a similar pattern during an 800 m freestyle race. Future research is need to understand if this lack of pace and turn stability is the best way to enhance the performance, or if swimmers should be advised to control their pace and turn. Nevertheless, coaches are advised to help swimmers with feedback about their pace (i.e., controlling the intermediate 30 m) and turn performances (i.e., controlling the 5 m in and 15 m out), leading to a positive effect in their final race time.To LEN (Ligue Européenne de Natation) and Spiideo AB for providing the videos. This project was supported by the National Funds through FCT – Portuguese Foundation for Science and Technology ( UID/DTP/04045/2013 ) – and the European Fund for regional development ( FEDER ) allocated by European Union through the COMPETE 2020 Programme (POCI-01-0145-FEDER-006969). We would like also to thank the support of the University of Beira Interior and Santander Universities (Bolsa BIPD/ICIFCSH-Santander Universidades-UBI/2017).info:eu-repo/semantics/publishedVersio

Stellar equilibrium configurations of white dwarfs in the f(R,T)f(R,T) gravity

In this work we investigate the equilibrium configurations of white dwarfs in a modified gravity theory, na\-mely, $f(R,T)$ gravity, for which $R$ and $T$ stand for the Ricci scalar and trace of the energy-momentum tensor, respectively. Considering the functional form $f(R,T)=R+2\lambda T$, with $\lambda$ being a constant, we obtain the hydrostatic equilibrium equation for the theory. Some physical properties of white dwarfs, such as: mass, radius, pressure and energy density, as well as their dependence on the parameter $\lambda$ are derived. More massive and larger white dwarfs are found for negative values of $\lambda$ when it decreases. The equilibrium configurations predict a maximum mass limit for white dwarfs slightly above the Chandrasekhar limit, with larger radii and lower central densities when compared to standard gravity outcomes. The most important effect of $f(R,T)$ theory for massive white dwarfs is the increase of the radius in comparison with GR and also $f(R)$ results. By comparing our results with some observational data of massive white dwarfs we also find a lower limit for $\lambda$, namely, $\lambda >- 3\times 10^{-4}$.Comment: To be published in EPJ

Progression of world records in master swimming

Master sports is increasingly popular nad arguably becoming more competitive worldwideinfo:eu-repo/semantics/publishedVersio