Calibration of YSZ sensor for the measurement of oxygen concentration in Lbe

Although liquid lead-bismuth eutectic (LBE) is a good candidate for coolant in the sub-critical transmutation blanket, it is known to be corrosive to stainless steel tubes and containers used in nuclear installations. To prevent the long-term corrosion problem by producing and maintaining a protective oxide layer on exposed surface of stainless steel, it is essential to accurately measure and control the oxygen concentration dissolved in LBE. An automobile style voltametric oxygen sensors, with YSZ (Yttria Stabilized Zirconia) as electrolyte and molten bismuth saturated with oxygen as reference was selected. An instrumentation system was designed specifically for calibrating the YSZ sensor and measure oxygen concentration in LBE. An initial setup was built and some preliminary experiments were conducted to calibrate the oxygen sensor. A set of calibration curves of voltage vs. temperature ranging from 300°C to 500°C under various oxygen concentrations in liquid LBE was obtained and presented here. A new improvised setup and instrumentation have also been developed to obtain more accurate results for a wide range of temperature between 300°C to 700°C

On the electron-induced isotope fractionation in low temperature ³²O₂/³⁶O₂ ices—ozone as a case study

The formation of six ozone isotopomers and isotopologues, 16O16O16O, 18O18O18O, 16O16O18O, 18O18O16O, 16O18O16O, and 18O16O18O, has been studied in electron-irradiated solid oxygen 16O2 and 18O2 (1 : 1) ices at 11 K. Significant isotope effects were found to exist which involved enrichment of 18O-bearing ozone molecules. The heavy 18O18O18O species is formed with a factor of about six higher than the corresponding 16O16O16O isotopologue. Likewise, the heavy 18O18O16O species is formed with abundances of a factor of three higher than the lighter 16O16O18O counterpart. No isotope effect was observed in the production of 16O18O16O versus 18O16O18O. Such studies on the formation of distinct ozone isotopomers and isotopologues involving non-thermal, non-equilibrium chemistry by irradiation of oxygen ices with high energy electrons, as present in the magnetosphere of the giant planets Jupiter and Saturn, may suggest that similar mechanisms may contribute to the 18O enrichment on the icy satellites of Jupiter and Saturn such as Ganymede, Rhea, and Dione. In such a Solar System environment, energetic particles from the magnetospheres of the giant planets may induce non-equilibrium reactions of suprathermal and/or electronically excited atoms under conditions, which are quite distinct from isotopic enrichments found in classical, thermal gas phase reactions

When is it Better to Compare than to Score?

When eliciting judgements from humans for an unknown quantity, one often has the choice of making direct-scoring (cardinal) or comparative (ordinal) measurements. In this paper we study the relative merits of either choice, providing empirical and theoretical guidelines for the selection of a measurement scheme. We provide empirical evidence based on experiments on Amazon Mechanical Turk that in a variety of tasks, (pairwise-comparative) ordinal measurements have lower per sample noise and are typically faster to elicit than cardinal ones. Ordinal measurements however typically provide less information. We then consider the popular Thurstone and Bradley-Terry-Luce (BTL) models for ordinal measurements and characterize the minimax error rates for estimating the unknown quantity. We compare these minimax error rates to those under cardinal measurement models and quantify for what noise levels ordinal measurements are better. Finally, we revisit the data collected from our experiments and show that fitting these models confirms this prediction: for tasks where the noise in ordinal measurements is sufficiently low, the ordinal approach results in smaller errors in the estimation

Comparative study of anaphylaxis incidence in patients receiving anti-snake venom with or without prophylactic adrenaline: a prospective, randomized, blinded study

Background: Anti-snake venom serum (ASV) administered for snake-bite patients is the most specific treatment available. Unfortunately, it can cause severe anaphylaxis which can be fatal sometimes.Methods: Fifty patients were included in the study and randomly divided into group A, who received sub-cutaneous adrenaline before administration of anti-venom serum and group B who did not. Each group comprised of twenty-five patients. The incidences as well as the severity of anaphylaxis in both groups and also the effects of subcutaneous adrenaline on the hemodynamic were analysed.Results: Anaphylactic reactions were significantly less in group A than group B population (p0.05) implying that administration of sub-cutaneous adrenaline is safe.Conclusions: Prophylactic subcutaneous adrenaline before anti snake venom administration is highly efficacious and safe in reducing the incidence as well as severity of anaphylactic reactions

Vacuum ultraviolet photoabsorption of prime ice analogues of Pluto and Charon

Here we present the first Vacuum UltraViolet (VUV) photoabsorption spectra of ice analogues of Pluto and Charon ice mixtures. For Pluto the ice analogue is an icy mixture containing nitrogen (N2), carbon monoxide (CO), methane (CH4) and water (H2O) prepared with a 100:1:1:3 ratio, respectively. Photoabsorption of icy mixtures with and without H2O were recorded and no significant changes in the spectra due to presence of H2O were observed. For Charon a VUV photoabsorption spectra of an ice analogue containing ammonia (NH3) and H2O prepared with a 1:1 ratio was recorded, a spectrum of ammonium hydroxide (NH4OH) was also recorded. These spectra may help to interpret the P-Alice data from New Horizons

Estimation from Pairwise Comparisons: Sharp Minimax Bounds with Topology Dependence

Data in the form of pairwise comparisons arises in many domains, including preference elicitation, sporting competitions, and peer grading among others. We consider parametric ordinal models for such pairwise comparison data involving a latent vector $w^* \in \mathbb{R}^d$ that represents the "qualities" of the $d$ items being compared; this class of models includes the two most widely used parametric models--the Bradley-Terry-Luce (BTL) and the Thurstone models. Working within a standard minimax framework, we provide tight upper and lower bounds on the optimal error in estimating the quality score vector $w^*$ under this class of models. The bounds depend on the topology of the comparison graph induced by the subset of pairs being compared via its Laplacian spectrum. Thus, in settings where the subset of pairs may be chosen, our results provide principled guidelines for making this choice. Finally, we compare these error rates to those under cardinal measurement models and show that the error rates in the ordinal and cardinal settings have identical scalings apart from constant pre-factors.Comment: 39 pages, 5 figures. Significant extension of arXiv:1406.661