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

Minimal random code learning: Getting bits back from compressed model parameters

While deep neural networks are a highly successful model class, their large memory footprint puts considerable strain on energy consumption, communication bandwidth, and storage requirements. Consequently, model size reduction has become an utmost goal in deep learning. A typical approach is to train a set of deterministic weights, while applying certain techniques such as pruning and quantization, in order that the empirical weight distribution becomes amenable to Shannon-style coding schemes. However, as shown in this paper, relaxing weight determinism and using a full variational distribution over weights allows for more efficient coding schemes and consequently higher compression rates. In particular, following the classical bits-back argument, we encode the network weights using a random sample, requiring only a number of bits corresponding to the Kullback-Leibler divergence between the sampled variational distribution and the encoding distribution. By imposing a constraint on the Kullback-Leibler divergence, we are able to explicitly control the compression rate, while optimizing the expected loss on the training set. The employed encoding scheme can be shown to be close to the optimal information-theoretical lower bound, with respect to the employed variational family. Our method sets new state-of-the-art in neural network compression, as it strictly dominates previous approaches in a Pareto sense: On the benchmarks LeNet-5/MNIST and VGG-16/CIFAR-10, our approach yields the best test performance for a fixed memory budget, and vice versa, it achieves the highest compression rates for a fixed test performance

Pandemic influenza control in Europe and the constraints resulting from incoherent public health laws

© 2010 Martin et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.Background: With the emergence of influenza H1N1v the world is facing its first 21st century global pandemic. Severe Acute Respiratory Syndrome (SARS) and avian influenza H5N1 prompted development of pandemic preparedness plans. National systems of public health law are essential for public health stewardship and for the implementation of public health policy[1]. International coherence will contribute to effective regional and global responses. However little research has been undertaken on how law works as a tool for disease control in Europe. With co-funding from the European Union, we investigated the extent to which laws across Europe support or constrain pandemic preparedness planning, and whether national differences are likely to constrain control efforts. Methods: We undertook a survey of national public health laws across 32 European states using a questionnaire designed around a disease scenario based on pandemic influenza. Questionnaire results were reviewed in workshops, analysing how differences between national laws might support or hinder regional responses to pandemic influenza. Respondents examined the impact of national laws on the movements of information, goods, services and people across borders in a time of pandemic, the capacity for surveillance, case detection, case management and community control, the deployment of strategies of prevention, containment, mitigation and recovery and the identification of commonalities and disconnects across states. Results: Results of this study show differences across Europe in the extent to which national pandemic policy and pandemic plans have been integrated with public health laws. We found significant differences in legislation and in the legitimacy of strategic plans. States differ in the range and the nature of intervention measures authorized by law, the extent to which borders could be closed to movement of persons and goods during a pandemic, and access to healthcare of non-resident persons. Some states propose use of emergency powers that might potentially override human rights protections while other states propose to limit interventions to those authorized by public health laws. Conclusion: These differences could create problems for European strategies if an evolving influenza pandemic results in more serious public health challenges or, indeed, if a novel disease other than influenza emerges with pandemic potential. There is insufficient understanding across Europe of the role and importance of law in pandemic planning. States need to build capacity in public health law to support disease prevention and control policies. Our research suggests that states would welcome further guidance from the EU on management of a pandemic, and guidance to assist in greater commonality of legal approaches across states.Peer reviewe

Transcontextual model of motivation in the preaching of healthy lifestyles

El presente trabajo examinó la aplicación del Modelo Transcontextual de la Motivación en la predicción de estilos de vida saludables de atletas veteranos. Se utilizó una muestra de 682 atletas veteranos portugueses de ambos géneros, de edades comprendidas entre los 30 y los 76 años (M=43.64; DT=8.25), dónde a través de cuestionarios se ha medido: la satisfacción de las necesidades psicológicas básicas, la motivación, las variables del comportamiento planeado y los estilos de vida saludables. De las conclusiones alcanzadas en este trabajo, son de destacar la relevancia de fomentar la necesidad psicológica básica de relación social, ya que ésta favorecerá la motivación intrínseca, promoviendo un mayor control del comportamiento sobre las intenciones de los practicantes, generando así mejores hábitos alimenticios, hábitos de descanso y menor consumo de tabacoThe present paper has examined the application of the Transcontextual Model of motivation in the prediction of healthy lifestyles of veteran athletes. A sample of 682 Portuguese veteran athletes of both sexes, aged between 30 and 76 years (M = 43.64; SD = 8.25), were administered the following questionnaires: satisfaction of needs basic psychological, self-determination motivation, planned behavioral variables and healthy lifestyles. From the conclusions reached in this work, it is important to emphasize the importance of fostering the basic psychological need of relatedness, since this will favor the intrinsic motivation, promoting greater control of behavior over the intentions of practitioners, thus generating more healthy eating habits, rest habits and lower tobacco consumptio

Validation of the questionnaire of the transtheoretical model of change of physical exercise

El objetivo de este estudio fue traducir y validar al español el Cuestionario del Modelo Transteórico del Cambio de Ejercicio Físico de Prochaska y DiClemente (1983). Se utilizó una muestra de 812 personas, entre los 14 y los 88 años (29,5±21,7). Se realizó un análisis factorial confirmatorio, análisis de consistencia interna y validez predictiva. Los resultados del Cuestionario del Modelo Transteórico del Cambio de Ejercicio Físico presentaron valores adecuados (χ2/g.l = 4,3, CFI = 0,92, IFI = 0,92, TLI = 0,90, RMSEA = 0,06, SRMR = 0,05). La consistencia interna mostró valores encima de .70. Se halló una predicción positiva y significativa de los estadios más activos del Modelo Transteórico sobre la intención de ser físicamente activo. Este estudio ha permitido proporcionar un cuestionario válido y fiable para evaluar el estadio en el que se encuentran las personas con respecto a la práctica de ejercicio físico, en el ámbito españolThe aim of this study was to translate and validate in Spanish the Questionnaire of the Transtheoretical Model of Change of Physical Exercise, of Prochaska and DiClemente (1983), and also to make adaptations and modifications as needed. The sample was composed of 812 people, aged between 14 and 88 years (29.5+21.7). Confirmative factorial analysis, analysis of internal consistency and of predictive validity were carried out. After the confirmative factorial analysis, the Questionnaire of the Theoretical Model of Change of Physical Exercise showed acceptable results (x2/g.1=4,3, CFI=0,92, IFI= 0.92, TLI = 0.90, RMSEA = 0.06, SRMR = 0,05). Similarly, internal consistency obtained from the respective dimensions showed values above .70. A positive and significant prediction of the most active stages of the Transtheoretical Model (action and maintenance) was found on the ‘intention to be physically active’. This study has enabled the provision of a valid and reliable questionnair

GRB 170817A-GW170817-AT 2017gfo and the observations of NS-NS, NS-WD and WD-WD mergers

The LIGO-Virgo Collaboration has announced the detection of GW170817 and has associated it with GRB 170817A. These signals have been followed after 11 hours by the optical and infrared emission of AT 2017gfo. The origin of this complex phenomenon has been attributed to a neutron star-neutron star (NS-NS) merger. In order to probe this association we confront our current understanding of the gravitational waves and associated electromagnetic radiation with four observed GRBs originating in binaries composed of different combinations NSs and white dwarfs (WDs). We consider 1) GRB 090510 the prototype of NS-NS merger leading to a black hole (BH); 2) GRB 130603B the prototype of a NS-NS merger leading to massive NS (MNS) with an associated kilonova; 3) GRB 060614 the prototype of a NS-WD merger leading to a MNS with an associated kilonova candidate; 4) GRB 170817A the prototype of a WD-WD merger leading to massive WD with an associated AT 2017gfo-like emission. None of these systems support the above mentioned association. The clear association between GRB 170817A and AT 2017gfo has led to introduce a new model based on on a new subfamily of GRBs originating from WD-WD mergers. We show how this novel model is in agreement with the exceptional observations in the optical, infrared, X- and gamma-rays of GRB 170817A-AT 2017gfo.Comment: version accepted for publication in JCAP. Missing references adde