Oceanography of the Canadian Shelf of the Beaufort Sea: A Setting for Marine Life

Conservation of marine biodiversity in the Beaufort Sea demands that we understand what individual organisms require of their physical and geochemical environments in order to survive. Specifically, how do the extraordinary spatial and seasonal variations in ice cover, temperature, light, freshwater, turbidity, and currents of the Beaufort Sea define unique places or times critical to marine life? We start with the traditional "bottom-up" approach, which is to review the strongly seasonal physical forcing of the system, and from it to infer the resultant oceanographic regimes and seasons. This approach, while valuable, remains incomplete: this is due partly to limitations of the data and partly to our limited understanding of this complex system. The oceanographic features (e.g., upwelling regions, recurrent polynyas, coastal currents, sediment types and distributions) define the backdrop that animals "know and understand" in the sense of interacting with one another and finding food and habitat. We therefore seek clues to the underlying oceanographic processes in the behavioural patterns of fish, marine mammals, and birds. This "top-down" approach also has limitations, but it offers the opportunity to seek those connections in the system where climate change is likely to have its greatest impact on biological populations.La conservation de la biodiversité marine dans la mer de Beaufort passe par notre compréhension des éléments nécessaires à la survie des organismes individuels au sein de leur environnement physique et géochimique. En particulier, comment les variations spatiales et saisonnières extrêmes dans le couvert glaciel, la température, la lumière, l'eau douce, la turbidité et les courants de la mer de Beaufort définissent-elles des espaces uniques ou des périodes critiques à la vie marine? On commence avec l'approche traditionnelle "ascendante" qui consiste à examiner les pressions physiques largement saisonnières qui s'exercent sur le système, et on déduit les régimes et saisons océanographiques qui en découlent. Cette approche, tout en étant intéressante, reste incomplète, en partie à cause du manque de données et en partie à cause de notre compréhension insuffisante de ce système complexe. Les caractéristiques océanographiques (p. ex., les zones de remontée d'eau profonde, les polynies récurrentes, les courants côtiers, les types de sédiments et leur distribution) définissent l'arrière-plan que les animaux "connaissent et comprennent" au sens où ils y interagissent les uns avec les autres pour y trouver nourriture et habitat. On recherche par conséquent, dans les schémas de comportement des poissons, des mammifères marins et des oiseaux, des indices témoignant des processus océanographiques sous-jacents. Cette approche "descendante" a aussi ses limites, mais elle offre l'occasion de rechercher au sein du système les liens où le changement climatique est susceptible d'avoir le plus grand impact sur les populations biologiques

Universality for Black Hole Heat Engines Near Critical Points

Johnson has shown [arXiv:1703.06119] that in the vicinity of a critical point the efficiency of a black hole heat engine can approach the Carnot efficiency while maintaining finite power. We characterize and extend this result in several ways, and we show how the rate of approach to the Carnot efficiency is governed by the critical exponents. We apply these results to several classes of black holes to illustrate their validity. Odd-order Lovelock black holes are known to have isolated critical points for which the critical exponents differ from the mean field theory values, providing a non-trivial test of the results. In this case, our results indicate the impossibility of even-order Lovelock black holes with isolated critical points in this class: their existence would constitute a violation of the second law of thermodynamics.Comment: 23 pages, 1 figur

Metal complexes with varying intramolecular hydrogen bonding networks

Alfred Werner described the attributes of the primary and secondary coordination spheres in his development of coordination chemistry. To examine the effects of the secondary coordination sphere on coordination chemistry, a series of tripodal ligands containing differing numbers of hydrogen bond (H-bond) donors were used to examine the effects of H-bonds on Fe(II), Mn(II)–acetato, and Mn(III)–OH complexes. The ligands containing varying numbers of urea and amidate donors allowed for systematic changes in the secondary coordination spheres of the complexes. Two of the Fe(II) complexes that were isolated as their Bu4N+ salts formed dimers in the solid-state as determined by X-ray diffraction methods, which correlates with the number of H-bonds present in the complexes (i.e., dimerization is favored as the number of H-bond donors increases). Electron paramagnetic resonance (EPR) studies suggested that the dimeric structures persist in acetonitrile. The Mn(II) complexes were all isolated as their acetato adducts. Furthermore, the synthesis of a rare Mn(III)–OH complex via dioxygen activation was achieved that contains a single intramolecular H-bond; its physical properties are discussed within the context of other Mn(III)–OH complexes

Dietary sodium chloride effect in Nile tilapia fed with fish meal-free diets

Aim of study: To evaluate the effect of the dietary NaCl level for Nile tilapia fingerlings.Area of study: Palotina sector of Federal University of Paraná, in southern Brazil.Material and methods: An experiment was carried using 750 Nile tilapia fingerlings (4.61 ± 0.09 g) distributed in 30 1,000-L circular tanks in a completely randomized design with six treatments and five replicates. NaCl was added to extruded fish meal-free diets at 0.0, 2.5, 5.0, 7.5, 10.0 and 12.5 (g/kg). After the experimental period, fish were submitted to a 24 h-fast and weighed. All data were submitted to an analysis of variance and Tukey’s test followed by Levene’s test and regression test, using the Statistica 7.0® software package.Main results: Fish fed the NaCl-free diet presented better growth performance (p<0.05) compared to the other diets. Linear decrease effects on final weight (y = 50.1754 – 0.1672x, r2 = 0.6984), specific growth rate (y = 45.5418 – 0.1688x, r² = 0.6966), weight gain (y = 4.9465 – 0.008x; r² = 0.6886) and apparent feed conversion (y = 0.7113 + 0.0043x; r² = 0.7655) were noted. Efficiency and apparent protein retention were better in the NaCl-free diet (p<0.05). Significant differences (p<0.05) were observed for fillet fat and crude protein content. Increasing NaCl levels led to significant decreases (p<0.05) in Nile tilapia fingerling protein efficiency rates (y = 3.7804 - 0.0116x; r² = 0.6549).Research highlights: Thus, NaCl should not be included in fish meal-free diets for Nile tilapia fingerlings

On Ultrasmall Silicate Grains in the Diffuse Interstellar Medium

The abundance of both amorphous and crystalline silicates in very small grains is limited by the fact that the 10 micron silicate emission feature is not detected in the diffuse ISM. On the basis of the observed IR emission spectrum for the diffuse ISM, the observed ultraviolet extinction curve, and the 10 micron silicate absorption profile, we obtain upper limits on the abundances of ultrasmall (a < 15 Angstrom) amorphous and crystalline silicate grains. Contrary to previous work, as much as ~20% of interstellar Si could be in a < 15 Angstrom silicate grains without violating observational constraints. Not more than ~5% of the Si can be in crystalline silicates (of any size).Comment: Submitted to ApJ Letters, 11 pages, 4 figures, Late

The Stability of Bredigite and Other Ca-Mg Silicates

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65844/1/j.1151-2916.1980.tb10213.x.pd

A Cryogenic Silicon Interferometer for Gravitational-wave Detection

The detection of gravitational waves from compact binary mergers by LIGO has opened the era of gravitational wave astronomy, revealing a previously hidden side of the cosmos. To maximize the reach of the existing LIGO observatory facilities, we have designed a new instrument that will have 5 times the range of Advanced LIGO, or greater than 100 times the event rate. Observations with this new instrument will make possible dramatic steps toward understanding the physics of the nearby universe, as well as observing the universe out to cosmological distances by the detection of binary black hole coalescences. This article presents the instrument design and a quantitative analysis of the anticipated noise floor

First narrow-band search for continuous gravitational waves from known pulsars in advanced detector data

Spinning neutron stars asymmetric with respect to their rotation axis are potential sources of continuous gravitational waves for ground-based interferometric detectors. In the case of known pulsars a fully coherent search, based on matched filtering, which uses the position and rotational parameters obtained from electromagnetic observations, can be carried out. Matched filtering maximizes the signalto- noise (SNR) ratio, but a large sensitivity loss is expected in case of even a very small mismatch between the assumed and the true signal parameters. For this reason, narrow-band analysis methods have been developed, allowing a fully coherent search for gravitational waves from known pulsars over a fraction of a hertz and several spin-down values. In this paper we describe a narrow-band search of 11 pulsars using data from Advanced LIGO’s first observing run. Although we have found several initial outliers, further studies show no significant evidence for the presence of a gravitational wave signal. Finally, we have placed upper limits on the signal strain amplitude lower than the spin-down limit for 5 of the 11 targets over the bands searched; in the case of J1813-1749 the spin-down limit has been beaten for the first time. For an additional 3 targets, the median upper limit across the search bands is below the spin-down limit. This is the most sensitive narrow-band search for continuous gravitational waves carried out so far

Economic predictors of differences in interview faking between countries : economic inequality matters, not the state of economy

Many companies recruit employees from different parts of the globe, and faking behavior by potential employees is a ubiquitous phenomenon. It seems that applicants from some countries are more prone to faking compared to others, but the reasons for these differences are largely unexplored. This study relates country-level economic variables to faking behavior in hiring processes. In a cross-national study across 20 countries, participants (N = 3839) reported their faking behavior in their last job interview. This study used the random response technique (RRT) to ensure participants anonymity and to foster honest answers regarding faking behavior. Results indicate that general economic indicators (gross domestic product per capita [GDP] and unemployment rate) show negligible correlations with faking across the countries, whereas economic inequality is positively related to the extent of applicant faking to a substantial extent. These findings imply that people are sensitive to inequality within countries and that inequality relates to faking, because inequality might actuate other psychological processes (e.g., envy) which in turn increase the probability for unethical behavior in many forms