Reaction studied of steam with niobium and tantalum

Study reveals the kinetics of niobium and tantalum with steam at elevated temperatures to determine the suitability of high melting metals for fabrication of equipment for temperature steam environments. Niobium obeyed linear kinetics from 1050 degrees to 1500 degrees C but tantalum followed a paralinear rate law

Mean curvature flow in a Ricci flow background

Following work of Ecker, we consider a weighted Gibbons-Hawking-York functional on a Riemannian manifold-with-boundary. We compute its variational properties and its time derivative under Perelman's modified Ricci flow. The answer has a boundary term which involves an extension of Hamilton's Harnack expression for the mean curvature flow in Euclidean space. We also derive the evolution equations for the second fundamental form and the mean curvature, under a mean curvature flow in a Ricci flow background. In the case of a gradient Ricci soliton background, we discuss mean curvature solitons and Huisken monotonicity.Comment: final versio

A Comparison of Outcome Measures for Speech Motor Learning in Acquired Apraxia of Speech Using Motor Learning Guided Treatment

Purpose: The purpose of this study was to investigate potential benefits of using a qualitative and quantitative outcome measure of articulation accuracy and suprasegmental characteristics in isolation for speech motor learning in acquired apraxia of speech (AOS). Methods: Baseline, retention, and maintenance measures from an oral reading task of 2 speakers with chronic AOS and aphasia were rated using an 11-point multidimensional rating scale accounting for articulation and immediacy and a hybrid scale measuring number of correctly produced words, presence of distortions in correctly produced words, and immediacy of the production. Participants received motor learning guided treatment two days a week for eighteen sessions. Results: The multidimensional rating scale and the hybrid scale comparably represented speech motor changes related to articulation accuracy and immediacy of the production across the duration of the intervention. The hybrid scale provided a sensitive measure for individual differences in immediacy and presence of distortions not represented in the multidimensional rating scale. Conclusions: The results of this pilot study provide evidence to support the benefit of using a qualitative and quantitative outcome measure for speech motor changes in acquired AOS. The individual differences identified through the hybrid scale have clinical and research implications

Effects of suspended sediments, dissolved inorganic nutrients and salinity on fertilisation and embryo development in the coral Acropora millepora (Ehrenberg, 1834)

Exposure of coral reefs to river plumes carrying increasing loads of nutrients and sediments is a pressing issue for coral reefs around the world including the Great Barrier Reef (GBR). Laboratory experiments were conducted to investigate the effects of changes in inorganic nutrients (nitrate, ammonium and phosphate), salinity and various types of suspended sediments in isolation and in combination on rates of fertilisation and early embryonic development of the scleractinian coral Acropora millepora. Dose–response experiments showed that fertilisation declined significantly with increasing sediments and decreasing salinity, while inorganic nutrients at up to 20 μM nitrate or ammonium and 4 μM phosphate had no significant effect on fertilisation. Suspended sediments of ≥100 mg l−1 and salinity of 30 ppt reduced fertilisation by >50%. Developmental abnormality occurred in 100% of embryos at 30 ppt salinity, and no fertilisation occurred at ≤28 ppt. Another experiment tested interactions between sediment, salinity and nutrients and showed that fertilisation was significantly reduced when nutrients and low concentrations of sediments co-occurred, although both on their own had no effect on fertilisation rates. Similarly, while slightly reduced salinity on its own had no effect, fertilisation was reduced when it coincided with elevated levels of sediments or nutrients. Both these interactions were synergistic. A third experiment showed that sediments with different geophysical and nutrient properties had differential effects on fertilisation, possibly related to sediment and nutrient properties. The findings highlight the complex nature of the effects of changing water quality on coral health, particularly stressing the significance of water quality during coral spawning time

Concentration and localization of zinc during seed development and germination in wheat

In a field experiment, the effect of foliar Zn applications on the concentration of Zn in seeds of a bread wheat cultivar (Triticum aestivum L. cv. Balatilla) was studied during different stages of seed development. In addition, a staining method using dithizone (DTZ: diphenyl thiocarbazone) was applied to (1) study the localization of Zn in seeds, (2) follow the remobilization of Zn during germination, and (3) develop a rapid visual Zn screening method for seed and flour samples. In all seed development stages, foliar Zn treatments were effective in increasing seed Zn concentration. The highest Zn concentration in the seeds was found in the first stage of seed development (around the early milk stage); after this, seed Zn concentration gradually decreased until maturity. When reacting with Zn, DTZ forms a redcolored complex. The DTZ staining of seed samples revealed that Zn is predominantly located in the embryo and aleurone parts of the seeds. After 36 h of germination, the coleoptile and roots that emerged from seeds showed very intensive red color formation and had Zn concentrations up to 200 mg kg1, indicating a substantial remobilization of Zn from seed pools into the developing roots (radicle) and coleoptile. The DTZ staining method seems to be useful in ranking flour samples for their Zn concentrations. There was a close relationship between the seed Zn concentrations and spectral absorbance of the methanol extracts of the flour samples stained with DTZ. The results suggest that (1) accumulation of Zn in seeds is particularly high during early seed development, (2) Zn is concentrated in the embryo and aleurone parts, and (3) the DTZ staining method can be used as a rapid, semiquantitative method to estimate Zn concentrations of flour and seed samples and to screen genotypes for their Zn concentrations in seeds

Southern American University Undergraduates\u27 Attitudes toward Intrauterine Insemination Undertaken by Women of Differing Age, Marital Status and Sexual Orientation

Undergraduate college students in the southern U.S. were presented with vignettes about a fictional woman seeking to become pregnant via intrauterine insemination (IUI). Participants were randomly assigned to conditions in which the woman described was 26 or 41 years old, and single, married to a man, or married to a woman. After reading the vignettes, participants rated their expectations of the prospective mother’s preparedness for parenting, ability to provide quality of life for a child, risk for pregnancy complications and achieving a healthy pregnancy. Results yielded marginally significantly (p = .05) lower expectations of achieving a healthy pregnancy when the mother was over 40, and significantly (p \u3c .05) lower anticipation of preparedness for parenting and ability to provide quality of life when she was designated as single or married to a woman. We discuss findings in terms of bias favoring traditional families with a mother and father begun when the parents were in their twenties

In situ Activation of Bimetallic Pd−Pt Methane Oxidation Catalysts

This study investigates possible pathways to reduce water inhibition over Pd−Pt methane oxidation catalysts supported on alumina and a ceria‐zirconia mixed oxide under conditions typical for lean burn gas engines. Spatially resolved concentration and temperature profiles reveal that addition of hydrogen to the lean reaction mixture leads to significant heat production and an increase in methane conversion. Moreover, reductive pulses during operation are not only able to regenerate the catalyst deactivated by water by removal of OH‐groups from the catalyst surface, but even promote its activity after repeated application of pulsing for several hours. X‐ray absorption spectroscopy reveals the formation of a partially reduced PdO−Pd mixture during the pulsing, which explains the increase in activity. This state of high activity is stable for several hours under the tested lean conditions. The results presented in this study suggest an efficient in situ activation strategy to overcome water inhibition of methane total oxidation over Pd−Pt catalysts by careful process control

Calculus and heat flow in metric measure spaces and applications to spaces with Ricci bounds from below

This paper is devoted to a deeper understanding of the heat flow and to the refinement of calculus tools on metric measure spaces (X,d,m). Our main results are: - A general study of the relations between the Hopf-Lax semigroup and Hamilton-Jacobi equation in metric spaces (X,d). - The equivalence of the heat flow in L^2(X,m) generated by a suitable Dirichlet energy and the Wasserstein gradient flow of the relative entropy functional in the space of probability measures P(X). - The proof of density in energy of Lipschitz functions in the Sobolev space W^{1,2}(X,d,m). - A fine and very general analysis of the differentiability properties of a large class of Kantorovich potentials, in connection with the optimal transport problem. Our results apply in particular to spaces satisfying Ricci curvature bounds in the sense of Lott & Villani [30] and Sturm [39,40], and require neither the doubling property nor the validity of the local Poincar\'e inequality.Comment: Minor typos corrected and many small improvements added. Lemma 2.4, Lemma 2.10, Prop. 5.7, Rem. 5.8, Thm. 6.3 added. Rem. 4.7, Prop. 4.8, Prop. 4.15 and Thm 4.16 augmented/reenforced. Proof of Thm. 4.16 and Lemma 9.6 simplified. Thm. 8.6 corrected. A simpler axiomatization of weak gradients, still equivalent to all other ones, has been propose

Upper bounds on the first eigenvalue for a diffusion operator via Bakry-\'{E}mery Ricci curvature II

Let $L=\Delta-\nabla\varphi\cdot\nabla$ be a symmetric diffusion operator with an invariant measure $d\mu=e^{-\varphi}dx$ on a complete Riemannian manifold. In this paper we prove Li-Yau gradient estimates for weighted elliptic equations on the complete manifold with $|\nabla \varphi|\leq\theta$ and $\infty$-dimensional Bakry-\'{E}mery Ricci curvature bounded below by some negative constant. Based on this, we give an upper bound on the first eigenvalue of the diffusion operator $L$ on this kind manifold, and thereby generalize a Cheng's result on the Laplacian case (Math. Z., 143 (1975) 289-297).Comment: Final version. The original proof of Theorem 2.1 using Li-Yau gradient estimate method has been moved to the appendix. The new proof is simple and direc

On Minimum Violations Ranking in Paired Comparisons

Ranking a set of objects from the most dominant one to the least, based on the results of paired comparisons, proves to be useful in many contexts. Using the rankings of teams or individuals players in sports to seed tournaments is an example. The quality of a ranking is often evaluated by the number of violations, cases in which an object is ranked lower than another that it has dominated in a comparison, that it contains. A minimum violations ranking (MVR) method, as its name suggests, searches specifically for rankings that have the minimum possible number of violations which may or may not be zero. In this paper, we present a method based on statistical physics that overcomes conceptual and practical difficulties faced by earlier studies of the problem.Comment: 10 pages, 10 figures; typos corrected (v2