The Expanding Fireball of Nova Delphini 2013

A classical nova occurs when material accreting onto the surface of a white dwarf in a close binary system ignites in a thermonuclear runaway. Complex structures observed in the ejecta at late stages could result from interactions with the companion during the common envelope phase. Alternatively, the explosion could be intrinsically bipolar, resulting from a localized ignition on the surface of the white dwarf or as a consequence of rotational distortion. Studying the structure of novae during the earliest phases is challenging because of the high spatial resolution needed to measure their small sizes. Here we report near-infrared interferometric measurements of the angular size of Nova Delphini 2013, starting from one day after the explosion and continuing with extensive time coverage during the first 43 days. Changes in the apparent expansion rate can be explained by an explosion model consisting of an optically thick core surrounded by a diffuse envelope. The optical depth of the ejected material changes as it expands. We detect an ellipticity in the light distribution, suggesting a prolate or bipolar structure that develops as early as the second day. Combining the angular expansion rate with radial velocity measurements, we derive a geometric distance to the nova of 4.54 +/- 0.59 kpc from the Sun.Comment: Published in Nature. 32 pages. Final version available at http://www.nature.com/nature/journal/v515/n7526/full/nature13834.htm

Secluded Dark Matter Coupled to a Hidden CFT

Models of secluded dark matter offer a variant on the standard WIMP picture and can modify our expectations for hidden sector phenomenology and detection. In this work we extend a minimal model of secluded dark matter, comprised of a U(1)'-charged dark matter candidate, to include a confining hidden-sector CFT. This provides a technically natural explanation for the hierarchically small mediator-scale, with hidden-sector confinement generating m_{gamma'}>0. Furthermore, the thermal history of the universe can differ markedly from the WIMP picture due to (i) new annihilation channels, (ii) a (potentially) large number of hidden-sector degrees of freedom, and (iii) a hidden-sector phase transition at temperatures T << M_{dm} after freeze out. The mediator allows both the dark matter and the Standard Model to communicate with the CFT, thus modifying the low-energy phenomenology and cosmic-ray signals from the secluded sector.Comment: ~50p, 8 figs; v2 JHEP versio

Cytogerontology since 1881: A reappraisal of August Weismann and a review of modern progress

Cytogerontology, the science of cellular ageing, originated in 1881 with the prediction by August Weismann that the somatic cells of higher animals have limited division potential. Weismann's prediction was derived by considering the role of natural selection in regulating the duration of an organism's life. For various reasons, Weismann's ideas on ageing fell into neglect following his death in 1914, and cytogerontology has only reappeared as a major research area following the demonstration by Hayflick and Moorhead in the early 1960s that diploid human fibroblasts are restricted to a finite number of divisions in vitro. In this review we give a detailed account of Weismann's theory, and we reveal that his ideas were both more extensive in their scope and more pertinent to current research than is generally recognised. We also appraise the progress which has been made over the past hundred years in investigating the causes of ageing, with particular emphasis being given to (i) the evolution of ageing, and (ii) ageing at the cellular level. We critically assess the current state of knowledge in these areas and recommend a series of points as primary targets for future research

Atlantic Leatherback Migratory Paths and Temporary Residence Areas

BACKGROUND: Sea turtles are long-distance migrants with considerable behavioural plasticity in terms of migratory patterns, habitat use and foraging sites within and among populations. However, for the most widely migrating turtle, the leatherback turtle Dermochelys coriacea, studies combining data from individuals of different populations are uncommon. Such studies are however critical to better understand intra- and inter-population variability and take it into account in the implementation of conservation strategies of this critically endangered species. Here, we investigated the movements and diving behaviour of 16 Atlantic leatherback turtles from three different nesting sites and one foraging site during their post-breeding migration to assess the potential determinants of intra- and inter-population variability in migratory patterns. METHODOLOGY/PRINCIPAL FINDINGS: Using satellite-derived behavioural and oceanographic data, we show that turtles used Temporary Residence Areas (TRAs) distributed all around the Atlantic Ocean: 9 in the neritic domain and 13 in the oceanic domain. These TRAs did not share a common oceanographic determinant but on the contrary were associated with mesoscale surface oceanographic features of different types (i.e., altimetric features and/or surface chlorophyll a concentration). Conversely, turtles exhibited relatively similar horizontal and vertical behaviours when in TRAs (i.e., slow swimming velocity/sinuous path/shallow dives) suggesting foraging activity in these productive regions. Migratory paths and TRAs distribution showed interesting similarities with the trajectories of passive satellite-tracked drifters, suggesting that the general dispersion pattern of adults from the nesting sites may reflect the extent of passive dispersion initially experienced by hatchlings. CONCLUSIONS/SIGNIFICANCE: Intra- and inter-population behavioural variability may therefore be linked with initial hatchling drift scenarios and be highly influenced by environmental conditions. This high degree of behavioural plasticity in Atlantic leatherback turtles makes species-targeted conservation strategies challenging and stresses the need for a larger dataset (>100 individuals) for providing general recommendations in terms of conservation

Ribosome display of combinatorial antibody libraries derived from mice immunised with heat-killed Xylella fastidiosa and the selection of MopB-specific single-chain antibodies

Pierce's disease is a devastating lethal disease of Vitus vinifera grapevines caused by the bacterium Xylella fastidiosa. There is no cure for Pierce's disease and control is achieved predominantly by suppressing transmission of the glassy winged sharpshooter insect vector. We present a simple robust approach for the generation of panels of recombinant single chain antibodies against the surface exposed elements of X. fastidiosa that may have potential use in diagnosis and/or disease transmission blocking studies. In vitro combinatorial antibody ribosome display libraries were assembled from immunoglobulin transcripts rescued from the spleens of mice immunized with heat-killed X. fastidiosa. The libraries were used in a single round of selection against an outer-membrane protein MopB, resulting in the isolation of a panel of recombinant antibodies. The potential use of selected anti-MopB antibodies was demonstrated by the successful application of the 4XfMopB3 antibody in an ELISA, western blot and immunofluorescence assay. These immortalised in vitro recombinant single chain antibody libraries generated against heat killed X. fastidiosa are a resource for the Pierce's disease research community that may be readily accessed for the isolation of antibodies against a plethora of X. fastidiosa surface exposed antigenic molecules

Teste cardiopulmonar do exercício na prática clínica Cardiopulmonary stress testing in clinical practice

O teste cardiopulmonar do exercício (CPX) apresenta-se como uma metodologia de grande utilidade diagnóstica e prognóstica. O presente estudo teve por objetivo demonstrar que os dados obtidos em laboratório fora do ambiente hospitalar comportam-se como os dados descritos na literatura, com aplicabilidade na prática clínica em nosso meio. METODOLOGIA: Trata-se de um relato de experiência, através da análise retrospectiva dos casos. O CPX foi realizado em condições de laboratório controladas, com bocal e clipe nasal, protocolo de rampa em esteira rolante e eletrocardiograma de 13 canais. RESULTADOS: Entre os 261 testes, 53,3% eram em homens, idade média de 48,2 ± 14,3 anos; ativos (45,2%) ou sedentários (34,5%). A capacidade aeróbia máxima foi superior e com declínio significativo para cada década de aumento na faixa etária entre os homens, enquanto nas mulheres o declínio significativo ocorreu entre os 30 e 60 anos. As mulheres apresentaram maior distribuição (p = 0,0006) nas classes funcionais "em programa de treinamento ou bem treinadas e motivadas". O consumo de oxigênio pico (<img border=0 width=32 height=32 src="../../../../../img/revistas/rbme/v6n6/V-com-pontinho-menor.gif">O2) foi significativamente superior nos testes máximos, mas o <img border=0 width=32 height=32 src="../../../../../img/revistas/rbme/v6n6/V-com-pontinho-menor.gif">O2 do limiar anaeróbio (<img border=0 width=32 height=32 src="../../../../../img/revistas/rbme/v6n6/V-com-pontinho-menor.gif">O2LA) não apresentou diferenças significativas, quando o teste obtido foi máximo ou submáximo. A capacidade funcional, avaliada pelo <img border=0 width=32 height=32 src="../../../../../img/revistas/rbme/v6n6/V-com-pontinho-menor.gif">O2LA como porcentagem do <img border=0 width=32 height=32 src="../../../../../img/revistas/rbme/v6n6/V-com-pontinho-menor.gif">O2 máximo previsto, comparado à porcentagem do <img border=0 width=32 height=32 src="../../../../../img/revistas/rbme/v6n6/V-com-pontinho-menor.gif">O2 máximo atingido, classificou mais indivíduos com compromisso circulatório (p = 0,002) ou com menor aptidão física em comparação com pacientes ativos ou em programa de treinamento (p < 0,00001), exceto quando entre 50,0 e 59,0%, em que o critério empregado não influenciou a classificação funcional (p = 0,221). Não haver atingido 85,0% do <img border=0 width=32 height=32 src="../../../../../img/revistas/rbme/v6n6/V-com-pontinho-menor.gif">O2 máximo previsto foi a causa mais comum de anormalidade, mais freqüente e significativo entre as mulheres. CONCLUSÃO: Os dados obtidos são comparáveis aos descritos na literatura, sugerindo que o CPX é uma metodologia factível, que poderia ser empregada rotineiramente na prática clínica em nosso meio.<br>Cardiopulmonary stress testing (CPT) is a very useful tool to determine the diagnosis and prognosis in clinical practice. The objective of this study is to demonstrate that data obtained in a laboratory outside the hospital are similar to those described in the literature. METHODOLOGY: Patients were submitted to CPT, treadmill ramp protocol, and 13 lead electrocardiogram to evaluate CPT in the clinical practice. RESULTS: Among 261 CPT, 53.3% were male, mean age 48.2 ± 14.3 years, with active (45.2%) or sedentary (34.5%) lifestyle. Male patients showed higher maximal aerobic capacity (<img border=0 width=32 height=32 src="../../../../../img/revistas/rbme/v6n6/V-com-pontinho-menor.gif">O2 max) and a significant decrease of <img border=0 width=32 height=32 src="../../../../../img/revistas/rbme/v6n6/V-com-pontinho-menor.gif">O2 for each ten years of increment in age, but it decreased from 30 to 69 years in females. Females showed a significant higher (p = 0.0006) distribution in functional classes described as "in training programs or well trained and high motivation". A <img border=0 width=32 height=32 src="../../../../../img/revistas/rbme/v6n6/V-com-pontinho-menor.gif">O2 max was superior in maximal effort tests, but anaerobic threshold (<img border=0 width=32 height=32 src="../../../../../img/revistas/rbme/v6n6/V-com-pontinho-menor.gif">O2AT) did not show differences between maximal or submaximal tests. The functionalcapacity evaluated by <img border=0 width=32 height=32 src="../../../../../img/revistas/rbme/v6n6/V-com-pontinho-menor.gif">O2AT as a fraction (%) of the <img border=0 width=32 height=32 src="../../../../../img/revistas/rbme/v6n6/V-com-pontinho-menor.gif">O2 max predicted in comparison to the fraction of the <img border=0 width=32 height=32 src="../../../../../img/revistas/rbme/v6n6/V-com-pontinho-menor.gif">O2 max measured was more rigorous, which implies a higher number of patients with circulatory impairment (p = 0.002) and also with lower physical capacity as opposed to active patients or patients under training programs (p < 0.00001); however, between 50.0% and 59.0% of the patients could be classified equally by one or the other criteria (p = 0.221). The more frequent abnormality in CPT was that it did not achieve 85.0% of the <img border=0 width=32 height=32 src="../../../../../img/revistas/rbme/v6n6/V-com-pontinho-menor.gif">O2 max predicted, more significant for females. CONCLUSION: Despite the limitations, this experience indicates that CPT data are reproducible in a laboratory outside the hospital, suggesting that CPT may be applied in clinical practice