The Radio Continuum of the Metal-Deficient Blue Compact Dwarf Galaxy SBS0335-052

We present new Very Large Array observations at five frequencies, from 1.4 to 22GHz, of the extremely low-metallicity blue compact dwarf SBS0335-052. The radio spectrum shows considerable absorption at 1.49GHz, and a composite thermal+non-thermal slope. After fitting the data with a variety of models, we find the best-fitting geometry to be one with free-free absorption homogeneously intermixed with the emission of both thermal and non-thermal components. The best-fitting model gives an an emission measure EM ~ 8x10^7pc cm^{-6} and a diameter of the radio-emitting region D ~17pc. The inferred density is n_e ~ 2000 cm^{-3}. The thermal emission comes from an ensemble of \~9000 O7 stars, with a massive star-formation rate (>=5Msun) of 0.13-0.15 yr^{-1}, and a supernova rate of 0.006 yr^{-1}. We find evidence for ionized gas emission from stellar winds, since the observed Bralpha line flux significantly exceeds that inferred from the thermal radio emission. The non-thermal fraction at 5GHz is ~0.7, corresponding to a non-thermal luminosity of ~2x10^{20} W Hz^{-1}. We attribute the non-thermal radio emission to an ensemble of compact SN remnants expanding in a dense interstellar medium, and derive an equipartition magnetic field of ~0.6-1 mG, and a pressure of \~3x10^{-8}-1x10^{-7} dyne cm^{-2}. If the radio properties of SBS0335-052 are representative of star formation in extremely low-metallicity environments, derivations of the star formation rate from the radio continuum in high redshift primordial galaxies need to be reconsidered. Moreover, photometric redshifts inferred from ``standard'' spectral energy distributions could be incorrect.Comment: 25 pages, including 3 figures, accepted for publication in Ap

Attention Enhances the Retrieval and Stability of Visuospatial and Olfactory Representations in the Dorsal Hippocampus

Attention enhances the encoding and retrieval of olfactory and visuospatial representations by modulating place field stability, firing rate, and neuronal synchronization of pyramidal cells in the hippocampus

Nonlinearity and Topology

The interplay of nonlinearity and topology results in many novel and emergent properties across a number of physical systems such as chiral magnets, nematic liquid crystals, Bose-Einstein condensates, photonics, high energy physics, etc. It also results in a wide variety of topological defects such as solitons, vortices, skyrmions, merons, hopfions, monopoles to name just a few. Interaction among and collision of these nontrivial defects itself is a topic of great interest. Curvature and underlying geometry also affect the shape, interaction and behavior of these defects. Such properties can be studied using techniques such as, e.g. the Bogomolnyi decomposition. Some applications of this interplay, e.g. in nonreciprocal photonics as well as topological materials such as Dirac and Weyl semimetals, are also elucidated

A História da Alimentação: balizas historiográficas

Os M. pretenderam traçar um quadro da História da Alimentação, não como um novo ramo epistemológico da disciplina, mas como um campo em desenvolvimento de práticas e atividades especializadas, incluindo pesquisa, formação, publicações, associações, encontros acadêmicos, etc. Um breve relato das condições em que tal campo se assentou faz-se preceder de um panorama dos estudos de alimentação e temas correia tos, em geral, segundo cinco abardagens Ia biológica, a econômica, a social, a cultural e a filosófica!, assim como da identificação das contribuições mais relevantes da Antropologia, Arqueologia, Sociologia e Geografia. A fim de comentar a multiforme e volumosa bibliografia histórica, foi ela organizada segundo critérios morfológicos. A seguir, alguns tópicos importantes mereceram tratamento à parte: a fome, o alimento e o domínio religioso, as descobertas européias e a difusão mundial de alimentos, gosto e gastronomia. O artigo se encerra com um rápido balanço crítico da historiografia brasileira sobre o tema

The Effects of Feature Necessity and Extrinsicity on Category Contrast in Natural Language Categories

This experiment tested two hypotheses: 1) that categories represented by features that many people believe to be necessary will demonstrate stronger category contrast than those represented by features that few people believe to be necessary, and 2) that categories that people believe are represented primarily by intrinsic features (i.e., features true of an entity in isolation) will have stronger category contrast than those that people believe are represented primarily by extrinsic features (i.e., features that represent relations between an entity and other entities). The findings support only the second hypothesis

Geo-spatial risk factor analysis for drug overdose death in South Florida from 2014 to 2019, and the independent contribution of social determinants of health

The physical environment and social determinants of health have been shown to influence health behaviors including drug use and fatal drug overdose. The current research examines the effects of the built environment, social determinants of health measures and aggregated risk from the built environment at neighborhood-level on drug overdose death locations in Miami-Dade County, Florida.Risk Terrain Modeling (RTM) was used to assess the place features risk factors that significantly increase the risk of drug overdose death spatially in Miami-Dade County ZIP Code Tabulation Areas, Florida from 2014 to 2019. An aggregated neighborhood risk of fatal drug overdose measure was developed by averaging the risk per grid cell from the RTM within census block groups each year. Six logistic and zero-inflated regression models were built to examine the effects of three indices of incident-specific social determinants of health (IS-SDH) measures and aggregated risk measures separately, and simultaneously on drug overdose death locations each year.Seven place features including parks, bus stops, restaurants and grocery stores were significantly related to the occurrence of fatal drug overdoses. When examined separately, one or more indices of the IS-SDH were significant covariates of drug overdose locations in some years. When examined simultaneously, the three indices of the IS-SDH and aggregated risk of fatal drug overdose measure could be all significant in certain years.The patterns of high-risk areas and place features identified from the RTM related to drug overdose deaths may be used to inform the placement of treatment and prevention resources. A multi-factor approach that combines an aggregated neighborhood risk measure reflecting the risk from the built environment and the incident-specific social determinants of health measures can be used to identify the drug overdose death locations in certain years.•Risk terrain modeling (RTM) identified high-risk locations for drug overdose deaths across years in Miami-Dade County.•The RTM risk scores improved the model fit over the model containing social determinants of health.•Patterns of high-risk locations and significant place feature risk factors can be used to inform prevention strategies