26,749 research outputs found
Wellbeing and brain structure: A comprehensive phenotypic and genetic study of image-derived phenotypes in the UK Biobank
Wellbeing, an important component of mental health, is influenced by genetic and environmental factors. Previous association studies between brain structure and wellbeing have typically focused on volumetric measures and employed small cohorts. Using the UK Biobank Resource, we explored the relationships between wellbeing and brain morphometrics (volume, thickness and surface area) at both phenotypic and genetic levels. The sample comprised 38,982 participants with neuroimaging and wellbeing phenotype data, of which 19,234 had genotypes from which wellbeing polygenic scores (PGS) were calculated. We examined the association of wellbeing phenotype and PGS with all brain regions (including cortical, subcortical, brainstem and cerebellar regions) using multiple linear models, including (1) basic neuroimaging covariates and (2) additional demographic factors that may synergistically impact wellbeing and its neural correlates. Genetic correlations between genomic variants influencing wellbeing and brain structure were also investigated. Small but significant associations between wellbeing and volumes of several cerebellar structures (β = 0.015–0.029, PFDR = 0.007–3.8 × 10−9), brainstem, nucleus accumbens and caudate were found. Cortical associations with wellbeing included volume of right lateral occipital, thickness of bilateral lateral occipital and cuneus, and surface area of left superior parietal, supramarginal and pre-/post-central regions. Wellbeing-PGS was associated with cerebellar volumes and supramarginal surface area. Small mediation effects of wellbeing phenotype and PGS on right VIIIb cerebellum were evident. No genetic correlation was found between wellbeing and brain morphometric measures. We provide a comprehensive overview of wellbeing-related brain morphometric variation. Notably, small effect sizes reflect the multifaceted nature of this concept
Measurement and Particle Statistics in the Szilard Engine
A Szilard Engine is a hypothetical device which is able to extract work from
a single thermal reservoir by measuring the position of particles within the
engine. We derive the amount of work that can be extracted from such a device
in the low temperature limit. Interestingly, we show this work is determined by
the information gain of the initial measurement rather than by the number and
type of particles which constitute the working substance. Our work provides
another clear connection between information gain and extractable work in
thermodynamical processes.Comment: 4 page
Successive spin-flop transitions of a Neel-type antiferromagnet Li2MnO3 single crystal with a honeycomb lattice
We have carried out high magnetic field studies of single-crystalline Li2MnO3, a honeycomb lattice antiferromagnet. Its magnetic phase diagram was mapped out using magnetization measurements at applied fields up to 35 T. Our results show that it undergoes two successive meta-magnetic transitions around 9 T fields applied perpendicular to the ab plane (along the c* axis). These phase transitions are completely absent in the magnetization measured with the field applied along the ab plane. In order to understand this magnetic phase diagram, we developed a mean-field model starting from the correct Neel-type magnetic structure, consistent with our single crystal neutron diffraction data at zero field. Our model calculations succeeded in explaining the two meta-magnetic transitions that arise when Li2MnO3 enters two different spin-flop phases from the zero field Neel phase.open1187Nsciescopu
Pure spinor computation towards open string three-loop
Using the recent results in the pure spinor formulation, we lay out a
ground-work towards the full momentum space amplitudes of open superstrings at
three-loop. After briefly reviewing the one-loop amplitude, we directly work
out the two-loop and reproduce the result that was obtained by a symmetry
argument. For the three-loop, first we use the two-loop regulator as a warm-up
exercise. The result vanishes. We then employ the regulator that has been
recently proposed by Aisaka and Berkovits (AB). It is noted that the terms in
higher power in that render the two-loop
regulator disqualified for the three-loop do not contribute. This with a few
other indications suggests a possibility that the AB regulator might also lead
to a vanishing result. Nevertheless, we argue that it is possible to acquire
the three-loop amplitude, and present a result that we anticipate to be the
three-loop amplitude.Comment: 41 pages, latex, cosmetic change
Staged and non-staged anaerobic filters : microbial activity segregation, hydrodynamic behaviour and performance
This work describes a comparative study of staged and non-staged anaerobic flters for treating a synthetic dairy waste under similar operating conditions.
The effect of increasing the substrate concentration from 3 to 12 g COD dmˉ³ at a constant hydraulic residence time (HRT) of 2 days was evaluated with
respect to overall reactor performance, biogas production, volatile fatty acids
profiles along the height, methanogenic and acidogenic activity distribution, and
hydrodynamic behaviour. The potential maximum specific methanogenic activity
against acetate, hydrogen, propionate and butyrate and the lactose specific activity
were determined for sludge sampled from three different points in each
reactor, under two operating conditions (influent COD of 3 and 9 g COD
dmˉ³). Although all trophic groups involved in the anaerobic process were
found throughout the reactors, it was possible to identify different specific
sludges at different heights in both reactors. Performances of the two configurations
were very similar under the operating conditions tested and the plug flow
behaviour of the staged reactor was clearly reduced when the influent concentration
increased from 3 to 9 g COD dmˉ³.EU Human Capital and Mobility network Improved Application of Anaerobic
Digestion Technology - EXBCHRXCT 930262.Fundação para a Ciência e a Tecnologia – PEAM/SEL/517/95
3′-UTR engineering to improve soluble expression and fine-tuning of activity of cascade enzymes in Escherichia coli
3'-Untranslated region (3'UTR) engineering was investigated to improve solubility of heterologous proteins (e.g., Baeyer-Villiger monooxygenases (BVMOs)) in Escherichia coli. Insertion of gene fragments containing putative RNase E recognition sites into the 3'UTR of the BVMO genes led to the reduction of mRNA levels in E. coli. Importantly, the amounts of soluble BVMOs were remarkably enhanced resulting in a proportional increase of in vivo catalytic activities. Notably, this increase in biocatalytic activity correlated to the number of putative RNase E endonucleolytic cleavage sites in the 3'UTR. For instance, the biotransformation activity of the BVMO BmoF1 (from Pseudomonas fluorescens DSM50106) in E. coli was linear to the number of RNase E cleavage sites in the 3'UTR. In summary, 3'UTR engineering can be used to improve the soluble expression of heterologous enzymes, thereby fine-tuning the enzyme activity in microbial cells.1184Ysciescopu
Gravel pits support waterbird diversity in an urban landscape
We assessed the benefit of 11 gravel pits for the settlement of waterbird communities in an urbanized area lacking natural wetlands. Gravel pits captured 57% of the regional species pool of aquatic birds. We identified 39 species, among which five were regionally rare. We used the Self Organizing Map algorithm to calculate the probabilities of presence of species, and to bring out habitat conditions that predict assemblage patterns. The age of the pits did not correlate with assemblage composition and species richness. There was a positive influence of macrophyte cover on waterbird species richness. Larger pits did not support more species, but species richness increased with connectivity. As alternative wetland habitats, gravel pits are attractive to waterbirds, when they act as stepping stones that ensure connectivity between larger natural and/or artificial wetlands separated in space
High Performance Electrocatalysts Based on Pt Nanoarchitecture for Fuel Cell Applications
Fuel cells, converting chemical energy from fuels into electricity directly without the need for combustion, are promising energy conversion devices for their potential applications as environmentally friendly, energy efficient power sources. However, to take fuel cell technology forward towards commercialization, we need to achieve further improvements in electrocatalyst technology, which can play an extremely important role in essentially determining cost-effectiveness, performance, and durability. In particular, platinum- (Pt-) based electrocatalyst approaches have been extensively investigated and actively pursued to meet those demands as an ideal fuel cell catalyst due to their most outstanding activity for both cathode oxygen reduction reactions and anode fuel oxidation reactions. In this review, we will address important issues and recent progress in the development of Pt-based catalysts, their synthesis, and characterization. We will also review snapshots of research that are focused on essential dynamics aspects of electrocatalytic reactions, such as the shape effects on the catalytic activity of Pt-based nanostructures, the relationships between structural morphology of Pt-based nanostructures and electrochemical reactions on both cathode and anode electrodes, and the effects of composition and electronic structure of Pt-based catalysts on electrochemical reaction properties of fuel cells.</jats:p
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