11 research outputs found
Validation of the Wiedemann-Franz Law in solid and molten tungsten above 2000 K through thermal conductivity measurements via steady state temperature differential radiometry
We measure the thermal conductivity of solid and molten tungsten using Steady
State Temperature Differential Radiometry. We demonstrate that the thermal
conductivity can be well described by application of Wiedemann-Franz Law to
electrical resistivity data, thus suggesting the validity of Wiedemann-Franz
Law to capture the electronic thermal conductivity of metals in their molten
phase. We further support this conclusion using ab initio molecular dynamics
simulations with a machine-learned potential. Our results show that at these
high temperatures, the vibrational contribution to thermal conductivity is
negligible compared to the electronic component
Genetic variation in a member of the laminin gene family affects variation in body composition in Drosophila and humans
<p>Abstract</p> <p>Background</p> <p>The objective of the present study was to map candidate loci influencing naturally occurring variation in triacylglycerol (TAG) storage using quantitative complementation procedures in <it>Drosophila melanogaster</it>. Based on our results from <it>Drosophila</it>, we performed a human population-based association study to investigate the effect of natural variation in <it>LAMA5 </it>gene on body composition in humans.</p> <p>Results</p> <p>We identified four candidate genes that contributed to differences in TAG storage between two strains of <it>D. melanogaster</it>, including <it>Laminin A </it>(<it>LanA</it>), which is a member of the α subfamily of laminin chains. We confirmed the effects of this gene using a viable <it>LanA </it>mutant and showed that female flies homozygous for the mutation had significantly lower TAG storage, body weight, and total protein content than control flies. <it>Drosophila LanA </it>is closely related to human <it>LAMA5 </it>gene, which maps to the well-replicated obesity-linkage region on chromosome 20q13.2-q13.3. We tested for association between three common single nucleotide polymorphisms (SNPs) in the human <it>LAMA5 </it>gene and variation in body composition and lipid profile traits in a cohort of unrelated women of European American (EA) and African American (AA) descent. In both ethnic groups, we found that SNP rs659822 was associated with weight (EA: <it>P </it>= 0.008; AA: <it>P </it>= 0.05) and lean mass (EA: <it>P= </it>0.003; AA: <it>P </it>= 0.03). We also found this SNP to be associated with height (<it>P </it>= 0.01), total fat mass (<it>P </it>= 0.01), and HDL-cholesterol (<it>P </it>= 0.003) but only in EA women. Finally, significant associations of SNP rs944895 with serum TAG levels (<it>P </it>= 0.02) and HDL-cholesterol (<it>P </it>= 0.03) were observed in AA women.</p> <p>Conclusion</p> <p>Our results suggest an evolutionarily conserved role of a member of the laminin gene family in contributing to variation in weight and body composition.</p
Assessing interactions between the associations of common genetic susceptibility variants, reproductive history and body mass index with breast cancer risk in the breast cancer association consortium: a combined case-control study.
INTRODUCTION: Several common breast cancer genetic susceptibility variants have recently been identified. We aimed to determine how these variants combine with a subset of other known risk factors to influence breast cancer risk in white women of European ancestry using case-control studies participating in the Breast Cancer Association Consortium. METHODS: We evaluated two-way interactions between each of age at menarche, ever having had a live birth, number of live births, age at first birth and body mass index (BMI) and each of 12 single nucleotide polymorphisms (SNPs) (10q26-rs2981582 (FGFR2), 8q24-rs13281615, 11p15-rs3817198 (LSP1), 5q11-rs889312 (MAP3K1), 16q12-rs3803662 (TOX3), 2q35-rs13387042, 5p12-rs10941679 (MRPS30), 17q23-rs6504950 (COX11), 3p24-rs4973768 (SLC4A7), CASP8-rs17468277, TGFB1-rs1982073 and ESR1-rs3020314). Interactions were tested for by fitting logistic regression models including per-allele and linear trend main effects for SNPs and risk factors, respectively, and single-parameter interaction terms for linear departure from independent multiplicative effects. RESULTS: These analyses were applied to data for up to 26,349 invasive breast cancer cases and up to 32,208 controls from 21 case-control studies. No statistical evidence of interaction was observed beyond that expected by chance. Analyses were repeated using data from 11 population-based studies, and results were very similar. CONCLUSIONS: The relative risks for breast cancer associated with the common susceptibility variants identified to date do not appear to vary across women with different reproductive histories or body mass index (BMI). The assumption of multiplicative combined effects for these established genetic and other risk factors in risk prediction models appears justified.RIGHTS : This article is licensed under the BioMed Central licence at http://www.biomedcentral.com/about/license which is similar to the 'Creative Commons Attribution Licence'. In brief you may : copy, distribute, and display the work; make derivative works; or make commercial use of the work - under the following conditions: the original author must be given credit; for any reuse or distribution, it must be made clear to others what the license terms of this work are
Predictions and Measurements of Thermal Conductivity of Ceramic Materials at High Temperature
The lattice thermal conductivity () of two ceramic materials, cerium
dioxide (CeO) and magnesium oxide (MgO), is computed up to 1500 K using
first principles and the phonon Boltzmann Transport Equation (PBTE) and
compared to time-domain thermoreflectance (TDTR) measurements up to 800 K.
Phonon renormalization and the four-phonon effect, along with high temperature
thermal expansion, are integrated in our \textit{ab initio} molecular dynamics
(AIMD) calculations. This is done by first relaxing structures and then fitting
to a set of effective force constants employed in a temperature-dependent
effective potential (TDEP) method. Both three-phonon and four-phonon scattering
rates are computed based on these effective force constants. Our calculated
thermal conductivities from the PBTE solver agree well with literature and our
TDTR measurements. Other predicted thermal properties including thermal
expansion, frequency shift, and phonon linewidth also compare well with
available experimental data. Our results show that high temperature softens
phonon frequency and reduces four-phonon scattering strength in both ceramics.
Compared to MgO, we find that CeO has weaker four-phonon effect and
renormalization greatly reduces its four-phonon scattering rates
Mathematical techniques for quantitative elemental analysis by energy dispersive X-ray fluorescence
Intention to Leave Self-employment: A Comparison of Business Owners and the Independently Self-employed
Update: Interim Guidance for the Diagnosis, Evaluation, and Management of Infants with Possible Congenital Zika Virus Infection — United States, October 2017
Mitochondrial Permeability Transition in the CNS - Composition, Regulation, and Pathophysiological Relevance
Mitochondrial permeability transition (MPT) is induced in isolated brain mitochondria by calcium and oxidants and is inhibited by adenine nucleotides. When induced, MPT is associated with equilibration of solutes of <1500 Da across the inner mitochondrial membrane. A persistent induction of MPT depolarizes the inner membrane and causes cessation of ATP synthesis, swelling of the matrix, and bursting of the mitochondrial membranes. The rupture of the membranes releases calcium stored in the mitochondrial matrix and apoptogenic factors from the intermembrane space, leading to cell death. MPT has been implicated in acute brain injury and neurodegenerative disease since inhibitors of MPT such as cyclosporin A (CsA) are brain protective. Whether MPT has a physiological role is unclear, but MPT may be important in calcium homeostasis under conditions of excessive neuronal activity