On the Progenitors of Core-Collapse Supernovae

Theory holds that a star born with an initial mass between about 8 and 140 times the mass of the Sun will end its life through the catastrophic gravitational collapse of its iron core to a neutron star or black hole. This core collapse process is thought to usually be accompanied by the ejection of the star's envelope as a supernova. This established theory is now being tested observationally, with over three dozen core-collapse supernovae having had the properties of their progenitor stars directly measured through the examination of high-resolution images taken prior to the explosion. Here I review what has been learned from these studies and briefly examine the potential impact on stellar evolution theory, the existence of "failed supernovae", and our understanding of the core-collapse explosion mechanism.Comment: 7 Pages, invited review accepted for publication by Astrophysics and Space Science (special HEDLA 2010 issue

Manganese Defective Clustering: Influence on the Spectroscopic Features of Ceria-Based Nanomaterials

The influence of manganese modification on the spectroscopic features of manganese-doped CeO2 systems synthesized by the microwave-assisted hydrothermal route and their correlation with the presence of O defective structures were verified, focusing on their interaction with poisonous atmospheres. Raman and electron paramagnetic resonance studies confirmed the presence of defective clusters formed by dipoles and/or quadrupoles. The number of paramagnetic species was found to be inversely proportional to the doping concentration, resulting in an increase in the Mn2+ signal, likely due to the reduction of Mn3+ species after the interaction with CO. X-ray photoelectron spectroscopy data showed the pure system with 33% of its cerium species in the Ce3+ configuration, with an abrupt decrease to 19%, after the first modification with Mn, suggesting that 14% of the Ce3+ species are donating one electron to the Mn2+ ions, thus becoming nonparamagnetic Ce4+ species. On the contrary, 58% of the manganese species remain in the Mn2+ configuration with five unpaired electrons, corroborating the paramagnetic feature of the samples seen in the electron paramagnetic resonance study

Low temperature transport in AC-driven Quantum Dots in the Kondo regime

We present a fully nonequilibrium calculation of the low temperature transport properties of a quantum dot in the Kondo regime when an AC potential is applied to the gate voltage. We solve a time dependent Anderson model with finite on-site Coulomb interaction. The interaction self-energy is calculated up to second order in perturbation theory in the on-site interaction, in the context of the Keldysh non-equilibrium technique, and the effect of the AC voltage is taken into account exactly for all ranges of AC frequencies and AC intensities. The obtained linear conductance and time-averaged density of states of the quantum dot evolve in a non trivial way as a function of the AC frequency and AC intensity of the harmonic modulation.Comment: 30 pages,7 figure

Kondo effect in coupled quantum dots: a Non-crossing approximation study

The out-of-equilibrium transport properties of a double quantum dot system in the Kondo regime are studied theoretically by means of a two-impurity Anderson Hamiltonian with inter-impurity hopping. The Hamiltonian, formulated in slave-boson language, is solved by means of a generalization of the non-crossing approximation (NCA) to the present problem. We provide benchmark calculations of the predictions of the NCA for the linear and nonlinear transport properties of coupled quantum dots in the Kondo regime. We give a series of predictions that can be observed experimentally in linear and nonlinear transport measurements through coupled quantum dots. Importantly, it is demonstrated that measurements of the differential conductance ${\cal G}=dI/dV$, for the appropriate values of voltages and inter-dot tunneling couplings, can give a direct observation of the coherent superposition between the many-body Kondo states of each dot. This coherence can be also detected in the linear transport through the system: the curve linear conductance vs temperature is non-monotonic, with a maximum at a temperature $T^*$ characterizing quantum coherence between both Kondo states.Comment: 20 pages, 17 figure

New perspectives for natural antimicrobial peptides : Application as antinflammatory drugs in a murine model

Background: Antimicrobial peptides (AMPs) are an ancient group of defense molecules. AMPs are widely distributed in nature (being present in mammals, birds, amphibians, insects, plants, and microorganisms). They display bactericidal as well as immunomodulatory properties. The aim of this study was to investigate the antimicrobial and anti-inflammatory activities of a combination of two AMPs (temporin B and the royal jellein I) against Staphylococcus epidermidis.Results: The temporin B (TB-KK) and the royal jelleins I, II, III chemically modified at the C terminal (RJI-C, RJII-C, RJIII-C), were tested for their activity against 10 different Staphylococcus epidermidis strains, alone and in combination. Of the three royal jelleins, RJI-C showed the highest activity. Moreover, the combination of RJI-C and TB-KK (MIX) displayed synergistic activity. In vitro, the MIX displayed low hemolytic activity, no NO2- production and the ability to curb the synthesis of the pro-inflammatory cytokines TNF-\uce\ub1 and IFN-\uce\ub3 to the same extent as acetylsalicylic acid. In vivo, the MIX sterilized mice infected with Staphylococcus epidermidis in eleven days and inhibited the expression of genes encoding the prostaglandin-endoperoxide synthase 2 (COX-2) and CD64, two important parameters of inflammation.Conclusion: The study shows that the MIX - a combination of two naturally occurring peptides - displays both antimicrobial and anti-inflammatory activities

Physical distancing and mental well-being in youth population of Portugal and Brazil during the COVID-19 pandemic

Funding Information: This paper was made possible with the scholarship from FCT and to the Unidade de I&D CHRC – Comprehensive Health Research Centre (UI/BD/150908/2021). Also to CAPES (Code 001) and CNPQ (Research Productivity Scholarship Process 304483/2018-4). The databases are anonymous, guaranteeing data confidentiality. Funding Information: Fundação para a ciência e tecnologia (FCT) and the Unidade de I&D CHRC – Comprehensive Health Research Centre (UI/BD/150908/2021). Also to CAPES (Code 001) and CNPQ (Research Productivity Scholarship Process 304483/2018-4) Publisher Copyright: © 2022Background: The COVID-19 pandemic may affect youth's physical and mental well-being, partially because of the countries' rules to contain the virus from spreading. However, there is still uncertainty about the impact of physical distancing on youth's mental health. We aimed to estimate the prevalence of feeling agitated, anxious, down, sad, or low mood (FNF) due to physical distance measures and verify which factors are associated with young Portuguese and Brazilian people. Methods: We used cross-sectional data from the instrument "COVID-19 Barometer: Social Opinion"in Portugal (March 2020 and September 2021) and from "COVID-19 Social Thermometer"in Brazil (August 2020 to April 2021); these surveys included data regarding the health and socioeconomic impact on the population. The health and sociodemographic variables of the two countries were summarized as absolute and relative frequencies. A multivariable logistic regression model was fit by country to estimate the relation between FNF and selected variables of interest. Results: Approximately 36% of the sample studied reported anxiety, agitation, sadness, or low mood almost every day in Portugal and 52% in Brazil due to physical distancing. In Portugal, having more than two comorbidities represented a greater chance of experiencing FNF every day or almost every day (odds ratio [OR] = 1.51 [CI: 1.22-1.87]) than those without comorbidities. In contrast, having a university education level represented a protector factor (OR = 0.76 [CI: 0.67-0.88]). In Brazil, being unemployed increased the chance of FNF compared to students (OR = 11.2). Conclusions: Physical distancing measures have impacted the mental well-being of the young population in Portugal and Brazil. The countries must make a quick effort to attend to and protect young people's well-being and mental health in the changing context of the current pandemic.publishersversioninpres

Coastal upwelling in the Rías Bajas, NW Spain: Contrasting the benthic regimes of Rías de Arosa and de Muros

Versión del editor0,986

Protocol for collection and separation of bone marrow mononuclear cells in Chlorocebus aethiops

Abstract: Chlorocebus aethiops is a species of non-human primate frequently used in biomedical research. Some research involves this species as an experimental model for various diseases and possible treatment with stem cells. The bone marrow is one of the main sources of these cells and provides easy access. The aim of this study was to standardize the protocol of collection and separation of bone marrow in C. aethiops. Ten animals were submitted to puncture of bone marrow with access to the iliac crest and cell separation by density gradient. The bone marrow of C. aethiops had an average of 97% viability. From the results achieved, we can conclude that C. aethiops is an excellent model to obtain and isolate mononuclear cells from bone marrow, fostering several studies in the field of cell therapy