The effect of temperature-dependent solubility on the onset of thermosolutal convection in a horizontal porous layer

We consider the onset of thermosolutal (double-diffusive) convection of a binary fluid in a horizontal porous layer subject to fixed temperatures and chemical equilibrium on the bounding surfaces, in the case when the solubility of the dissolved component depends on temperature. We use a linear stability analysis to investigate how the dissolution or precipitation of this component affects the onset of convection and the selection of an unstable wavenumber; we extend this analysis using a Galerkin method to predict the structure of the initial bifurcation and compare our analytical results with numerical integration of the full nonlinear equations. We find that the reactive term may be stabilizing or destabilizing, with subtle effects particularly when the thermal gradient is destabilizing but the solutal gradient is stabilizing. The preferred spatial wavelength of convective cells at onset may also be substantially increased or reduced, and strongly reactive systems tend to prefer direct to subcritical bifurcation. These results have implications for geothermal-reservoir management and ore prospecting

Opportunities for Public Aquariums to Increase the Sustainability of the Aquatic Animal Trade

The global aquatic pet trade encompasses a wide diversity of freshwater and marine organisms. While relying on a continual supply of healthy, vibrant aquatic animals, few sustainability initiatives exist within this sector. Public aquariums overlap this industry by acquiring many of the same species through the same sources. End users are also similar, as many aquarium visitors are home aquarists. Here we posit that this overlap with the pet trade gives aquariums significant opportunity to increase the sustainability of the trade in aquarium fishes and invertebrates. Improving the sustainability ethos and practices of the aquatic pet trade can carry a conservation benefit in terms of less waste, and protection of intact functioning ecosystems, at the same time as maintaining its economic and educational benefits and impacts. The relationship would also move forward the goal of public aquariums to advance aquatic conservation in a broad sense. For example, many public aquariums in North America have been instrumental in working with the seafood industry to enact positive change toward increased sustainability. The actions include being good consumers themselves, providing technical knowledge, and providing educational and outreach opportunities. These same opportunities exist for public aquariums to partner with the ornamental fish trade, which will serve to improve business, create new, more ethical and more dependable sources of aquatic animals for public aquariums, and perhaps most important, possibly transform the home aquarium industry from a threat, into a positive force for aquatic conservation. Zoo Biol. 32:1-12, 2013. © 2012 Wiley Periodicals, Inc

Abstract 482: Differences in Ground Reaction Forces and Chest Compression Release Velocity in Professional and Lay Rescuers With and Without the Use of Real-Time CPR Feedback

Purpose: Chest compression release velocity (CCRV) has been associated with survival and favorable neurological outcome after cardiac resuscitation. Both complete chest release and high CCRV contribute to improved venous return during CPR. Differences in compression forces delivered by professional and lay rescuers are reported, which may contribute to differences in CCRV. The aim of this pilot study was to investigate differences in ground reaction force (GRF) and CCRV between professional and lay rescuers during CPR performed on a manikin with and without real-time feedback. Methods: Professional (n = 5) and lay rescuers (n = 11) performed two minutes of continuous compressions on a manikin positioned over a force plate for two trials. CPR feedback provided by a defibrillator was disabled in the first trial and enabled in the second. CPR pads containing an accelerometer were used to calculate individual compression characteristics. Relative maximum and minimum GRFs were calculated for each compression cycle and averaged over each trial. Paired and independent sample t tests and Pearson correlations were conducted in STATA 15.1. Results: CCRV was higher in professionals vs. lay rescuers with feedback disabled and enabled (p\u3c0.05). Professionals had greater maximal and lower minimum forces than lay rescuers without feedback (p\u3c0.05), though there were no differences between groups with feedback enabled (Table 1). CCRV was associated with minimum force (r = -0.63, p\u3c0.01) and force range (r = 0.78, p\u3c0.01) in all rescuers. Analysis of GRFs by CCRV for all rescuers indicated lower force minimum (9.71 + 3.16 N, p\u3c0.05) with CCRV \u3e400 mm/s in comparison to CCRV 300-400 mm/s (39.73 + 8.91 N) and CCRV 200-300 mm/s (63.82 + 16.98 N). Conclusions: CPR feedback attenuated differences in GRF between professional and lay rescuers. CCRV was greater in professionals and was associated with measures of GRF, and thus may serve as an indicator of both velocity and amount of chest release

Kinematic differences between professional and lay rescuers with and without the use of real-time cpr feedback

Purpose: Guideline-compliant cardiopulmonary resuscitation (CPR) performance can be achieved with training and use of real-time feedback. Kinematic differences are reported between experts and novices in various motor tasks. The aim of this pilot study was to investigate differences in kinematics between professional and lay rescuers during CPR performed on a manikin with and without feedback. Methods: Professional (n = 5) and lay rescuers (n = 11) performed two minutes of continuous chest compressions on a manikin for two trials. Real-time CPR feedback provided by a defibrillator was disabled in the first trial and enabled in the second. CPR pads containing an accelerometer were used to calculate individual compression characteristics. Participants were instrumented for electromyography (EMG) and inertial motion capture and a motion capture marker was placed on the top hand. Paired and independent-sample t-tests and Pearson correlations were conducted in STATA 15.1. Results: CPR feedback increased compression depth in lay rescuers (p \u3c 0.05) to achieve guideline compliance. Lower bilateral hip range of motion (ROM) was recorded in lay rescuers compared with professionals without feedback (p \u3c 0.05), but hip ROM was increased in lay rescuers with feedback enabled (p \u3c 0.05). Hip ROM was associated with compression depth on both right (r = 0.61, p \u3c 0.01) and left sides (r = 0.65, p \u3c 0.01) for all rescuers. Greater left shoulder flexion was measured in lay rescuers both with (p \u3c 0.05) and without feedback (p \u3c 0.05). Lower extremity muscle coactivation indexes (CI) indicate greater hip extensor activity in professionals with feedback on both left (1.42 ± 0.17 vs. 0.87 ± 0.12, p \u3c 0.05) and right sides (1.33 ± 0.16 vs. 0.99 ± 0.07, p \u3c 0.05)

Quantitative Analysis of Genetic and Neuronal Multi-Perturbation Experiments

Perturbation studies, in which functional performance is measured after deletion, mutation, or lesion of elements of a biological system, have been traditionally employed in many fields in biology. The vast majority of these studies have been qualitative and have employed single perturbations, often resulting in little phenotypic effect. Recently, newly emerging experimental techniques have allowed researchers to carry out concomitant multi-perturbations and to uncover the causal functional contributions of system elements. This study presents a rigorous and quantitative multi-perturbation analysis of gene knockout and neuronal ablation experiments. In both cases, a quantification of the elements' contributions, and new insights and predictions, are provided. Multi-perturbation analysis has a potentially wide range of applications and is gradually becoming an essential tool in biology

Opening the Black Box of Administrative Reform: A Strategic-Relational Analysis of Agency Responses to Termination Threats

How do public agencies respond when reform proposals threaten downsizing, reduction in functions, or termination? Agency survival during administrative reform is conventionally explained by structural characteristics, informed by the hardwiring thesis derived from the politics of the U.S. federal government. Parliamentary systems provide greater opportunity for agency reform, but there is little evidence of how agencies respond to such proposals or how proposals are altered prior to decision. We consider agencies as active participants in the reform processes, using strategic-relational theory to analyse their strategizing. The article employs detailed empirical evidence on 12 agencies subject to reform by the UK government between 2010 and 2013. We identify three archetypical defence strategies—technical expert, network node, and marginal adaptor—and argue that coding agency strategies alongside structural analysis can help better explain reform outcomes

Squamous Cell Carcinoma of the Skin and Coal Tar Creosote Exposure in a Railroad Worker

A 50-year-old male railroad worker presented to his primary care physician with an erythematous, tender skin lesion on the right knee; a biopsy of this lesion revealed squamous cell carcinoma in situ. The site of the lesion was sun-protected but had been associated with 30 years of creosote-soaked clothing. In this article, we review dermal and other malignancies associated with creosote, along with creosote occupational exposures and exposure limits. This is a unique case, given the lack of other, potentially confounding, polyaromatic hydrocarbons and the sun-protected location of the lesion

Isotope Geochemistry of Proterozoic Talc Occurrences in Archean Marbles of the Ruby Mountains, Southwest Montana, U.S.A

Talc occurs as massive, economic deposits in upper amphibolite facies marbles of Archean age in southwestern Montana. Previous workers have demonstrated that the talc is a replacement of the marble that resulted from interaction with a large volume of fluid. δ18O (SMOW) values for dolomite and calcite range from 20-25‰ for the unaltered Archean marbles to as little as 8-10‰ in the talc deposits, suggesting that the metasomatic fluids had low δ18O values. In contrast, δ13C values for calcite and dolomite are similar for all samples (-2 to +2‰ PDB). Therefore, it is likely that the metasomatic fluids were oxygen-rich and carbon-poor, namely water-rich and CO2-poor. A CO2-poor fluid is also indicated by Δ13C (calcite-graphite) values (3.6-5.3‰), which appear little altered from values expected for upper amphibolite facies marbles, and by the occurrence of the mineral assemblage talc+calcite, 40Ar/39Ar age spectra for hornblende, phlogopite, and biotite record cooling at 1.72 Ga from a regional thermal event. 40Ar/39Ar age spectra of fine-grained muscovite associated with the talc date talc formation at 1.36 Ga. The Ar data limit the temperature of talc crystallization to below ∼350 DEGC, the biotite closure temperature for Ar diffusion. If the metasomatic fluid was seawater (0‰), then the carbonate oxygen data require a minimum temperature of 270 DEGC for talc formation. Oxygen (δ18O = 4.7 to 8.8‰) and hydrogen (D/H = -49.9 to -57.6 SMOW) isotope data for the talc are consistent with a 200-300 DEGC metasomatic fluid derived from seawater, based on theoretical models of the fractionation of oxygen and hydrogen between talc and water. Regional, northwest-trending faults associated with the extension that formed the Belt Basin in the Middle Proterozoic may have provided channels for seawater to circulate in continental crust and to react with marble, forming talc at depths of 5-10 km

Architecture of human Rag GTPase heterodimers and their complex with mTORC1

© 2019 American Association for the Advancement of Science. All rights reserved. The Rag guanosine triphosphatases (GTPases) recruit the master kinase mTORC1 to lysosomes to regulate cell growth and proliferation in response to amino acid availability. The nucleotide state of Rag heterodimers is critical for their association with mTORC1. Our cryo–electron microscopy structure of RagA/RagC in complex with mTORC1 shows the details of RagA/RagC binding to the RAPTOR subunit of mTORC1 and explains why only the RagAGTP/RagCGDPnucleotide state binds mTORC1. Previous kinetic studies suggested that GTP binding to one Rag locks the heterodimer to prevent GTP binding to the other. Our crystal structures and dynamics of RagA/RagC show the mechanism for this locking and explain how oncogenic hotspot mutations disrupt this process. In contrast to allosteric activation by RHEB, Rag heterodimer binding does not change mTORC1 conformation and activates mTORC1 by targeting it to lysosomes