2,753 research outputs found

    Mixed-state microwave response in superconducting cuprates

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    We report measurements of the magnetic-field induced microwave complex resistivity in REBa2_{2}Cu3_{3}O7−δ_{7-\delta} thin films, with RE = Y, Sm. Measurements are performed at 48 GHz by means of a resonant cavity in the end-wall-replacement configuration. The magnetic field dependence is investigated by applying a moderate (0.8 T) magnetic field along the c-axis. The measured vortex state complex resistivity in YBa2_{2}Cu3_{3}O7−δ_{7-\delta} and SmBa2_{2}Cu3_{3}O7−δ_{7-\delta} is analyzed within the well-known models for vortex dynamics. It is shown that attributing the observed response to vortex motion alone leads to inconsistencies in the as-determined vortex parameters (such as the vortex viscosity and the pinning constant). By contrast, attributing the entire response to field-induced pair breaking leads to a nearly quantitative description of the data.Comment: 6 pages, 4 figures, to be published in J. Supercond. as proceedings of 8th HTSHFF (May 26th-29th, 2004, Begur, Spain

    Prey selection by an apex predator : the importance of sampling uncertainty.

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    The impact of predation on prey populations has long been a focus of ecologists, but a firm understanding of the factors influencing prey selection, a key predictor of that impact, remains elusive. High levels of variability observed in prey selection may reflect true differences in the ecology of different communities but might also reflect a failure to deal adequately with uncertainties in the underlying data. Indeed, our review showed that less than 10% of studies of European wolf predation accounted for sampling uncertainty. Here, we relate annual variability in wolf diet to prey availability and examine temporal patterns in prey selection; in particular, we identify how considering uncertainty alters conclusions regarding prey selection. Over nine years, we collected 1,974 wolf scats and conducted drive censuses of ungulates in Alpe di Catenaia, Italy. We bootstrapped scat and census data within years to construct confidence intervals around estimates of prey use, availability and selection. Wolf diet was dominated by boar (61.5±3.90 [SE] % of biomass eaten) and roe deer (33.7±3.61%). Temporal patterns of prey densities revealed that the proportion of roe deer in wolf diet peaked when boar densities were low, not when roe deer densities were highest. Considering only the two dominant prey types, Manly's standardized selection index using all data across years indicated selection for boar (mean = 0.73±0.023). However, sampling error resulted in wide confidence intervals around estimates of prey selection. Thus, despite considerable variation in yearly estimates, confidence intervals for all years overlapped. Failing to consider such uncertainty could lead erroneously to the assumption of differences in prey selection among years. This study highlights the importance of considering temporal variation in relative prey availability and accounting for sampling uncertainty when interpreting the results of dietary studies

    Indicações Geográficas de Vinhos Brasileiros.

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    O tema das Indicações Geográficas (IG?s) não é contemporâneo. Desde os primórdios na antiga Grécia (século IV), há relatos de produtos que fazem relação com o lugar de origem como os vinhos de Corinto, as amêndoas de Naxos, o mel da Sicília e o mármore de Paros, enquanto no Império Romano, sob o reinado de Augustus, eram conhecidas as tâmaras do Egito, o presunto de Gália, as ostras de Brindisi e o mármore de Carrara. Na Bíblia. existem relatos de proteção de produtos como o vinho em Gedi (Cânticos I, 14), o cedro do Líbano (Cânticos III, 19 e Reis V, 6) que utilizavam uma espécie de sobrenome para produtos de diferentes origens, onde esta qualidade e diferenciação eram reconhecidas pelos consumidores (BRUSH, 2011; HATCHUEL, 2018, BERTOZZI, 1995, VALENTE et al., 2012)

    A bright impulsive solar burst detected at 30 THz

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    Ground- and space-based observations of solar flares from radio wavelengths to gamma-rays have produced considerable insights but raised several unsolved controversies. The last unexplored wavelength frontier for solar flares is in the range of submillimeter and infrared wavelengths. Here we report the detection of an intense impulsive burst at 30 THz using a new imaging system. The 30 THz emission exhibited remarkable time coincidence with peaks observed at microwave, mm/submm, visible, EUV and hard X-ray wavelengths. The emission location coincides with a very weak white-light feature, and is consistent with heating below the temperature minimum in the atmosphere. However, there are problems in attributing the heating to accelerated electrons. The peak 30 THz flux is several times larger than the usual microwave peak near 9 GHz, attributed to non-thermal electrons in the corona. The 30 THz emission could be consistent with an optically thick spectrum increasing from low to high frequencies. It might be part of the same spectral component found at sub-THz frequencies whose nature remains mysterious. Further observations at these wavelengths will provide a new window for flare studies.Comment: 9 pages, 11 figures, accepted by Astrophysical Journal, March 23, 201

    Risk factors for pre-clinical atherosclerosis in adolescents with type 1 diabetes

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    Aims: To assess whether, besides "traditional" risk factors, overall oxidative stress, oxidized lipoproteins, and glycemic variability are associated with early macro-vascular damage in type 1 diabetes (T1D). Methods: In 267 children/adolescents with T1D (130 girls, age 9.1-23.0 years) we evaluated: derivatives of reactive oxygen metabolites [d-ROMs], serum total antioxidant capacity [TAC] and oxidized LDL-cholesterol [oxLDL]; markers of early vascular damage (Lipoprotein-associated phospholipase A2 [Lp-PLA2], z-score of carotid intima-media thickness [z-cIMT] and carotid-femoral pulse wave velocity [z-PWV]); CGM metrics of four weeks preceding the visit, central systolic/diastolic blood pressures (cSBP/cDBP), and HbA1c, z-score of BP (z-SBP/z-DBP) and circulating lipids longitudinally collected since T1D onset.. Three general linear models were built with z-cIMT, z-PWV adjusted for current cDBP, and Lp-PLA2 as independent variables. Results: The z-cIMT was associated with male gender (B = 0.491, η2 = 0.029, p = 0.005), cSBP (B = 0.023, η2 = 0.026, p = 0.008) and oxLDL (B = 0.022, η2 = 0.022, p = 0.014). The z-PWV was associated with diabetes duration (B = 0.054, η2 = 0.024, p = 0.016), daily insulin dose (B = 0.52, η2 = 0.018, p = 0.045), longitudinal z-SBP (B = 0.18, η2 = 0.018, p = 0.045) and dROMs (B = 0.003, η2 = 0.037, p = 0.004). Lp-PLA2 was associated with age (B = 0.221, η2 = 0.079, p = 3*10-6), oxLDL (B = 0.081, η2 = 0.050, p = 2*10-4), longitudinal LDL-cholesterol (B = 0.031, η2 = 0.043, p = 0.001) and male gender (B = -1.62, η2 = 0.10, p = 1.3*107). Conclusions: Oxidative stress, male gender, insulin dose, diabetes duration and longitudinal lipids and blood pressure, contributed to the variance of early vascular damage in young patients with T1D

    Spatial variability of nitrogen dioxide and formaldehydeand residential exposure of children in the industrial area of Viadana, Northern Italy

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    Chipboard production is a source of ambient air pollution. We assessed the spatial variability of outdoor pollutants and residentialexposure of children living in proximity to the largest chipboard industry in Italy and evaluated the reliability of exposureestimates obtained from a number of available models. We obtained passive sampling data on NO2and formaldehyde collectedby the Environmental Protection Agency of Lombardy region at 25 sites in the municipality of Viadana during 10 weeks (2017-2018) and compared NO2measurements with average weekly concentrations from continuous monitors. We compared interpo-lated NO2and formaldehyde surfaces with previous maps for 2010. We assessed the relationship between residential proximity tothe industry and pollutant exposures assigned using these maps, as well as other available countrywide/continental models basedon routine data on NO2, PM10, andPM2.5. The correlation between NO2concentrations from continuous and passive samplingwas high (Pearson'sr= 0.89), although passive sampling underestimated NO2especially during winter. For both 2010 and 2017-2018, we observed higher NO2and formaldehyde concentrations in the south of Viadana, with hot-spots in proximity to theindustry. PM10and PM2.5exposures were higher for children at 3.5 km to theindustry, whereas NO2exposure was higher at 1-1.7 km to the industry. Road and population densities were also higher close tothe industry. Findings from a variety of exposure models suggest that children living in proximity to the chipboard industry inViadana are more exposed to air pollution and that exposure gradients are relatively stable over time

    Parâmetros sanguíneos da arraia de água doce Potamotrygon orbignyi Castelnau, 1855 (Potamotrygonidae) da Bacia do Rio Negro, Amazonas, Brasil.

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    A região Amazônica apresenta a maior diversidade de espécies de potamotrigonídeos, algumas com distribuição ampla como as arraias Paratrygon aiereba, Potamotrygon motoro e Potamotrygon orbignyi, sendo essa última encontrada nas bacias dos rios Amazonas, Orinoco e nos rios das Guianas e do Suriname. No Amazonas, as arraias de água doce são exploradas há mais de duas décadas pela pesca ornamental e, atualmente, cerca de 10.000 espécimes/ano são exportados. Deste total, 10% pertencem à espécie P. orbignyi, mesmo com participação aparentemente baixa, esta espécie é a mais valorizada entre todos os peixes ornamentais comercializados junto ao mercado internacional. A grande valorização de P. orbignyi se deve ao alto policromatismo, além da dificuldade de captura, uma vez que essa arraia vive associada às praias, margens de ilhas e igarapés de fundo arenoso e sem folhas. Embora a hematologia de peixes seja uma ferramenta biológica valiosa, o progresso no estabelecimento de parâmetros hematológicos das diversas espécies de peixes é lento e na literatura os dados são isolados e frequentemente incompletos, principalmente, no que se refere às arraias de água doce. Desta forma, este trabalho teve por objetivo descrever os parâmetros bioquímicos e hematológicos da arraia P. orbignyi
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