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In recent years, the interest with niobium alloys has been increasingly focusing on high-stress applications. This work shows the study of Cu-25wt.%Fe-25 wt.%Nb composite sintered by spark plasma at 700, 750, and 800 °C, under constant uniaxial pressure of 35 MPa for 3 min, evaluated for use as bushings. The scanning electron microscopy results showed regions rich in Nb and α-Fe embedded in a γ-Cu matrix, forming a solid solution of Fe-Nb suggesting the occurrence of a sintering process by Cu liquid phase and precipitation of an ε-phase Fe2Nb Laves. The relative density, mechanical and thermophysical properties were also evaluated. The alloy sintered at 800 °C showed hardness around 81 HB, low porosity, low porosity, yield strength 168 ± 4 MPa, modulus of elasticity 47 ± 4 GPa, and relative density 7.9% higher than the alloy prepared at 700 °C. The values of thermal conductivity obtained were above 70 Wm−1K−1, superior to SAE 65, indicating a possible material for application on bushings. [ABSTRACT FROM AUTHOR]

In modern weak-lensing surveys, the common approach to correct for residual systematic biases in the shear is to calibrate shape measurement algorithms using simulations. These simulations must fully capture the complexity of the observations to avoid introducing any additional bias. In this paper we study the importance of faint galaxies below the observational detection limit of a survey. We simulate simplified Euclid VIS images including and excluding this faint population, and measure the shift in the multiplicative shear bias between the two sets of simulations. We measure the shear with three different algorithms: a moment-based approach, model fitting, and machine learning. We find that for all methods, a spatially uniform random distribution of faint galaxies introduces a shear multiplicative bias of the order of a few times 10−3. This value increases to the order of 10−2 when including the clustering of the faint galaxies, as measured in the Hubble Space Telescope Ultra-Deep Field. The magnification of the faint background galaxies due to the brighter galaxies along the line of sight is found to have a negligible impact on the multiplicative bias. We conclude that the undetected galaxies must be included in the calibration simulations with proper clustering properties down to magnitude 28 in order to reach a residual uncertainty on the multiplicative shear bias calibration of a few times 10−4, in line with the 2 × 10−3 total accuracy budget required by the scientific objectives of the Euclid survey. We propose two complementary methods for including faint galaxy clustering in the calibration simulations. [ABSTRACT FROM AUTHOR]

Context. In the last decade, astronomers have found a new type of supernova called superluminous supernovae (SLSNe) due to their high peak luminosity and long light-curves. These hydrogen-free explosions (SLSNe-I) can be seen to z ∼ 4 and therefore, offer the possibility of probing the distant Universe. Aims. We aim to investigate the possibility of detecting SLSNe-I using ESA’s Euclid satellite, scheduled for launch in 2020. In particular, we study the Euclid Deep Survey (EDS) which will provide a unique combination of area, depth and cadence over the mission. Methods. We estimated the redshift distribution of Euclid SLSNe-I using the latest information on their rates and spectral energy distribution, as well as known Euclid instrument and survey parameters, including the cadence and depth of the EDS. To estimate the uncertainties, we calculated their distribution with two different set-ups, namely optimistic and pessimistic, adopting different star formation densities and rates. We also applied a standardization method to the peak magnitudes to create a simulated Hubble diagram to explore possible cosmological constraints. Results. We show that Euclid should detect approximately 140 high-quality SLSNe-I to z ∼ 3.5 over the first five years of the mission (with an additional 70 if we lower our photometric classification criteria). This sample could revolutionize the study of SLSNe-I at z > 1 and open up their use as probes of star-formation rates, galaxy populations, the interstellar and intergalactic medium. In addition, a sample of such SLSNe-I could improve constraints on a time-dependent dark energy equation-of-state, namely w(a), when combined with local SLSNe-I and the expected SN Ia sample from the Dark Energy Survey. Conclusions. We show that Euclid will observe hundreds of SLSNe-I for free. These luminous transients will be in the Euclid data-stream and we should prepare now to identify them as they offer a new probe of the high-redshift Universe for both astrophysics and cosmology. [ABSTRACT FROM AUTHOR]

We have used the Karl G. Jansky Very Large Array to image ~100 deg² of SDSS Stripe 82 at 1-2 GHz. The survey consists of 1026 snapshot observations of 2.5 min duration, using the hybrid CnB configuration. The survey has good sensitivity to diffuse, low surface brightness structures and extended radio emission, making it highly synergistic with existing 1.4 GHz radio observations of the region. The principal data products are continuum images, with 16 ? 10 arcsec resolution, and a catalogue containing 11 782 point and Gaussian components resulting from fits to the thresholded Stokes-I brightness distribution, forming approximately 8948 unique radio sources. The typical effective 1σ noise level is 88 μJy beam-1. Spectral index estimates are included, as derived from the 1 GHz of instantaneous bandwidth. Astrometric and photometric accuracy are in excellent agreement with existing narrowband observations. A large-scale simulation is used to investigate clean bias, which we extend into the spectral domain. Clean bias remains an issue for snapshot surveys with the VLA, affecting our total intensity measurements at the ~1σ level. Statistical spectral index measurements are in good agreement with existing measurements derived from matching separate surveys at two frequencies. At flux densities below ~35σ the median in-band spectral index measurements begin to exhibit a bias towards flatness that is dependent on both flux density and the intrinsic spectral index. In-band spectral curvature measurements are likely to be unreliable for all but the very brightest components. Image products and catalogues are publicly available via an FTP server. [ABSTRACT FROM AUTHOR]

The adaptive evolution of the Notothenia rossii occurred under the selective pressure of stable and low temperatures. It is an opportunistic feeder of Antarctic krill and the fluoride in the krill carapace is apparently not toxic. We investigated the interactive effect of fluoride, elevated temperatures, and low salinity on the plasmatic constituents of this Antarctic fish. The experiments were conducted at the Brazilian Antarctic Station Comandante Ferraz (EACF), located on King George Island. The Antarctic fish N. rossii was acclimatized to eight thermo-saline-trophic conditions, combining two temperatures (0 and 4 °C), two salinities (35 and 20), and two trophic conditions (with/without fluoride) for an 11-day period. Trophic fluoride was not able to alter the plasmatic levels of glucose, cholesterol, plasmatic protein, Cl −, Mg 2+, Ca 2+, and inorganic phosphate, but induced an acute elevation of triglycerides at 0 °C and salinity of 35. At low salinity, hyperglycemia, hypertriglyceridemia, and hypocalcemia were observed. The thermo-saline interaction at 4 °C was able to minimize the effects of fluoride and low salinity on the plasmatic constituents levels. [ABSTRACT FROM AUTHOR]

The aim of this study was to evaluate morphologic and biochemistry alterations caused by the addition of sodium nitroprusside (SNP), a NO donor, on bovine oocyte maturation in vitro.Bovine ovaries were collected at a local abattoir. COC were cultured in TCM-199 with 10% FCS, 0.5 μg mL-1FSH, 5.0 μg mL-1LH, and antibiotics. Analysis of variance was conducted and the means were compared by t-test at a level of 5%. Experimental design: (1) evaluation of the oocyte plasma membrane viability and integrity using Annexin V/propidium iodide (PI) and Hoechst 33342/PI staining, respectively; (2) microtubule and microfilament organization, and migration of cortical granules by immunofluorescence; (3) oocyte glutathione content and concentration of NO3-/NO2-using the method of Griess (Ricart-Jane D et al.2002 Nitric Oxide 6, 178-185) and (4) embryo development. In Experiment 1, the addition of 1 mMSNP caused cellular death in the majority of the oocytes [100%, AnnexinV/PI (+) and 80.7% Hoescht/IP (+)] differing from the control group and the 0.01 mMSNP (P 0.05). Nevertheless, in the group treated with 0.01 mMSNP the total cortical granule migration was greater (86.8%, P 0.05). The concentration of NO in the medium were similar to both control group (6.0 ± 3.0 μM) and treated with 0.01 mMSNP (15.8 ± 1.9 μM), however, the treatment with 1 mMSNP increased 10 times (59.9 ± 12.0 μM; P 0.05). Even so, in the group treated with 0.01 mMthere was a greater blastocyst cell number when compared to the control group (256.8 ± 52.5 and 196.9 ± 54.0, respectively-P< 0.05). These results indicate that: (1) the addition of 0.01 mMSNP increased the quality of the oocyte maturation, leading to a higher percentage of cortical granules migration and blastocyst cell numbers, in a different pathway from that of glutathione; (2) the addition of 1 mMof SNP caused a cytotoxic effect, leading to cellular death with loss of viability and integrity of plasma membrane, absence of nuclear maturation/organization of cytoskeleton and reduction of the glutathione content, although with no intervention in the migration of cortical granules. [ABSTRACT FROM AUTHOR]