Breakdown voltage estimation of a supercritical nitrogen plasma switch

Supercritical fluids (SCFs), characterized by a high pressure and high density, combine the advantages of gasses and liquids: high ability of mass transfer and high heat transfer. SCFs have a high potential as an electrical switching medium owing to their high breakdown strength, quick self healing, no bubble formation, high heat capacity, high heat conductivity, low viscosity, and low impact to the environment. In this work the thermodynamic characteristics of supercritical fluids are introduced. An experimental analysis of electrical breakdown phenomena of a supercritical plasma switch with pressure up to 180 bar is presented, focusing on the breakdown voltage variation as a function of the fluid pressure, gap width of the electrodes and fluid flow rate through the gap. A new design of a supercritical switch, with flexible gap width, flushing velocity, and repetitive voltage source is introduced

Decoding dissociation of sequence-specific protein-DNA complexes with non-equilibrium simulations

Sequence-specific protein-DNA interactions are crucial in processes such as DNA organization, gene regulation and DNA replication. Obtaining detailed insights into the recognition mechanisms of protein-DNA complexes through experiments is hampered by a lack of resolution in both space and time. Here, we present a molecular simulation approach to quantify the sequence specificity of protein-DNA complexes, that yields results fast, and is generally applicable to any protein-DNA complex. The approach is based on molecular dynamics simulations in combination with a sophisticated steering potential and results in an estimate of the free energy difference of dissociation. We provide predictions of the nucleotide specific binding affinity of the minor groove binding Histone-like Nucleoid Structuring (H-NS) protein, that are in agreement with experimental data. Furthermore, our approach offers mechanistic insight into the process of dissociation. Applying our approach to the major groove binding ETS domain in complex with three different nucleotide sequences identified the high affinity consensus sequence, quantitatively in agreement with experiments. Our protocol facilitates quantitative prediction of protein-DNA complex stability, while also providing high resolution insights into recognition mechanisms. As such, our simulation approach has the potential to yield detailed and quantitative insights into biological processes involving sequence-specific protein-DNA interactions

Breakdown voltage estimation of a supercritical nitrogen plasma switch

Supercritical fluids (SCFs), characterized by a high pressure and high density, combine the advantages of gasses and liquids: high ability of mass transfer and high heat transfer. SCFs have a high potential as an electrical switching medium owing to their high breakdown strength, quick self healing, no bubble formation, high heat capacity, high heat conductivity, low viscosity, and low impact to the environment. In this work the thermodynamic characteristics of supercritical fluids are introduced. An experimental analysis of electrical breakdown phenomena of a supercritical plasma switch with pressure up to 180 bar is presented, focusing on the breakdown voltage variation as a function of the fluid pressure, gap width of the electrodes and fluid flow rate through the gap. A new design of a supercritical switch, with flexible gap width, flushing velocity, and repetitive voltage source is introduced

Economic evaluation of embryo transfer protocols:Long-term costs and effects of reducing the number of twin pregnancies in IVF by single embryo transfer

In the past, more than one embryo was often replaced with IVF to increase the chance of a pregnancy. The flip side is that this also increases the chance of a multiple pregnancy. More and more often only one embryo is replaced because multiple pregnancies are associated with complications for mother and child. In this thesis, the long-term costs and outcomes of singles and multiple births born after IVF have been mapped and used to calculate the long-term cost-effectiveness of various embryo transfer strategies. The replacement of two embryos has the highest chance of success, but is also the most expensive. In terms of cost effectiveness, the preferred strategy depends on the analysis period. From an economic perspective, it is preferable to replace two embryos if the long-term costs and outcomes of the children are include

Numerical and experimental investigation of dielectric recovery in super-critical nitrogen

A supercritical (SC) nitrogen (N2) switch is designed and tested. The dielectric strength and recovery rate of the SC switch are investigated by experiments. In order to theoretically study the discharge and recovery process of the SC N2 switch under high repetition rate operation, a numerical model is developed. For SC N2 with initial parameters of p = 80.9 bar and T = 300 K, the simulation results show that within several nanoseconds after the streamer bridges the switch gap, the spark is fully developed and this time depends on the applied electric field between electrodes. During the whole discharge process, the maximum temperature in the channel is about 20 000 K. About 10μs after the spark excitation of 200 ns duration, the temperature on the axis decays to Taxis 1500 K, mainly contributed by the gas expansion and heat transfer mechanisms. After 100μs, the dielectric strength of the gap recovers to above half of the cold breakdown voltage due to the temperature decay in the channel. Both experimental and numerical investigations indicate that supercritical fluid is a good insulating medium that has a proved high breakdown voltage and fast recovery speed

What do IPAQ questions mean to older adults? Lessons from cognitive interviews

Most questionnaires used for physical activity (PA) surveillance have been developed for adults aged ≤65 years. Given the health benefits of PA for older adults and the aging of the population, it is important to include adults aged 65+ years in PA surveillance. However, few studies have examined how well older adults understand PA surveillance questionnaires. This study aimed to document older adults' understanding of questions from the International PA Questionnaire (IPAQ), which is used worldwide for PA surveillance

Physical activity and quality of life in older women with a history of depressive symptoms

Physical activity (PA) is positively associated with health-related quality of life (HRQL) in older adults. It is not evident whether this association applies to older adults with poor mental health. This study examined associations between PA and HRQL in older women with a history of depressive symptoms. Participants were 555 Australian women born in 1921–1926 who reported depressive symptoms in 1999 on a postal survey for the Australian Longitudinal Study on Women's Health. They completed additional surveys in 2002, 2005 and 2008 that assessed HRQL and weekly minutes walking, in moderate PA, and in vigorous PA. Random effects mixed models were used to examine concurrent and prospective associations between PA and each of 10 HRQL measures (eight SF-36 subscales; two composite scales). In concurrent models, higher levels of PA were associated with better HRQL (p\ua0\ua03 point differences) were evident for physical functioning, general health, vitality and social functioning. For women in their 70s–80s with a history of depressive symptoms, PA is positively associated with HRQL concurrently, and to a lesser extent prospectively. This study extends previous work by showing significant associations in older women with a history of depressive symptoms. Incorporating PA into depression management of older women may improve their HRQL

Cap analysis of gene expression reveals alternative promoter usage in a rat model of hypertension

The role of alternative promoter usage in tissue-specific gene expression has been well established, however, its role in complex diseases is poorly understood. We performed cap analysis of gene expression (CAGE) sequencing from the left ventricle (LV) of a rat model of hypertension, the spontaneously hypertensive rat (SHR), and a normotensive strain, Brown Norway (BN) to understand the role of alternative promoter usage in complex disease. We identified 26,560 CAGE-defined transcription start sites (TSS) in the rat LV, including 1,970 novel cardiac TSSs. We identified 28 genes with alternative promoter usage between SHR and BN, which could lead to protein isoforms differing at the amino terminus between two strains and 475 promoter switching events altering the length of the 5’ UTR. We found that the shift in Insr promoter usage was significantly associated with insulin levels and blood pressure within a panel of HXB/BXH recombinant inbred rat strains, suggesting that hyperinsulinemia due to insulin resistance might lead to hypertension in SHR. Our study provides a preliminary evidence of alternative promoter usage in complex diseases