119 research outputs found
Surface Hydrogen Modeling of Super Soft X-ray Sources: Are They Supernova Ia Progenitors?
Nova explosions occur on the white dwarf (WD) component of a Cataclysmic
Variable stellar system which is accreting matter lost by a companion. A Type
Ia supernova explosion is thought to result when a WD, in a similar binary
configuration, grows in mass to the Chandrasekhar Limit. Here, we present
calculations of accretion of Solar matter, at a variety of mass accretion
rates, onto hot (K), luminous (30L), massive
(1.25M, 1.35M) Carbon-Oxygen WDs. In contrast to our nova
simulations where the WD has a low initial luminosity and a thermonuclear
runaway (TNR) occurs and ejects material, these simulations do not eject
material (or only a small fraction of the accreted material) and the WD grows
in mass. A hydrogen TNR does not occur because hydrogen fuses to helium in the
surface layers, and we call this process Surface Hydrogen Burning (SHB). As the
helium layer grows in mass, it gradually fuses either to carbon and oxygen or
to more massive nuclei depending on the WD mass and mass accretion rate. If
such a WD were to explode in a SN Ia event, therefore, it would show neither
hydrogen nor helium in its spectrum as is observed. Moreover, the luminosities
and effective temperatures of our simulations agree with the observations of
some of the Super Soft X-ray Binary Sources and, therefore, our results
strengthen previous speculation that some of them (CAL 83 and CAL 87 for
example) are probably progenitors of SN Ia explosions. Finally, we have
achieved SHB for values of the mass accretion rate that almost span the
observed values of the Cataclysmic Variables.Comment: Accepted by APJL, 4 pages, 1 figure, LaTex (uses emulateapj.sty
Utilization of fish trash for increasing yield and quality of milk in cattle
The difference between cost of milk production and Its telling price Is very thin and Is
getting thinner due to cumulative increase in cattle food prices on one side and limitations on
marketing price of milk on the other. Possible utilization of trash fish converted to liquid silage
a* a part of cattle food resulting In Increased yield of milk and fat concern are discussed in
this paper. The development of silage and field trials on milking catties were carried out by
Gujarat Fisheries Aquatic Sciences Research Institute, Okha
A Role for Drosophila dFoxO and dFoxO 5′UTR Internal Ribosomal Entry Sites during Fasting
One way animals may cope with nutrient deprivation is to broadly repress translation by inhibiting 5′-cap initiation. However, under these conditions specific proteins remain essential to survival during fasting. Such peptides may be translated through initiation at 5′UTR Internal Ribosome Entry Sites (IRES). Here we show that the Drosophila melanogaster Forkhead box type O (dFoxO) transcription factor is required for adult survival during fasting, and that the 5′UTR of dfoxO has the ability to initiate IRES-mediated translation in cell culture. Previous work has shown that insulin negatively regulates dFoxO through AKT-mediated phosphorylation while dFoxO itself induces transcription of the insulin receptor dInR, which also harbors IRES. Here we report that IRES-mediated translation of both dFoxO and dInR is activated in fasted Drosophila S2 cells at a time when cap-dependent translation is reduced. IRES mediated translation of dFoxO and dInR may be essential to ensure function and sensitivity of the insulin signaling pathway during fasting
Naturally Occurring Genetic Variants in Human Chromogranin A (CHGA) Associated with Hypertension as well as Hypertensive Renal Disease
Chromogranin A (CHGA) plays a fundamental role in the biogenesis of catecholamine secretory granules. Changes in storage and release of CHGA in clinical and experimental hypertension prompted us to study whether genetic variation at the CHGA locus might contribute to alterations in autonomic function, and hence hypertension and its target organ consequences such as hypertensive renal disease (nephrosclerosis). Systematic polymorphism discovery across the human CHGA locus revealed both common and unusual variants in both the open reading frame and such regulatory regions as the proximal promoter and 3′-UTR. In chromaffin cell-transfected CHGA 3′-UTR and promoter/luciferase reporter plasmids, the functional consequences of the regulatory/non-coding allelic variants were documented. Variants in both the proximal promoter and the 3′-UTR displayed statistical associations with hypertension. Genetic variation in the proximal CHGA promoter predicted glomerular filtration rate in healthy twins. However, for hypertensive renal damage, both end-stage renal disease and rate of progression of earlier disease were best predicted by variants in the 3′-UTR. Finally, mechanistic studies were undertaken initiated by the clue that CHGA promoter variation predicted circulating endothelin-1. In cultured endothelial cells, CHGA triggered co-release of not only the vasoconstrictor and pro-fibrotic endothelin-1, but also the pro-coagulant von Willebrand Factor and the pro-angiogenic angiopoietin-2. These findings, coupled with stimulation of endothelin-1 release from glomerular capillary endothelial cells by CHGA, suggest a plausible mechanism whereby genetic variation at the CHGA locus eventuates in alterations in human renal function. These results document the consequences of genetic variation at the CHGA locus for cardiorenal disease and suggest mechanisms whereby such variation achieves functional effects
Available phosphorus levels in diets supplemented with phytase for male broilers aged 22 to 42 days kept in a high-temperature environment
Prediction and Testing of Biological Networks Underlying Intestinal Cancer
Colorectal cancer progresses through an accumulation of somatic mutations, some of which reside in so-called “driver” genes that provide a growth advantage to the tumor. To identify points of intersection between driver gene pathways, we implemented a network analysis framework using protein interactions to predict likely connections – both precedented and novel – between key driver genes in cancer. We applied the framework to find significant connections between two genes, Apc and Cdkn1a (p21), known to be synergistic in tumorigenesis in mouse models. We then assessed the functional coherence of the resulting Apc-Cdkn1a network by engineering in vivo single node perturbations of the network: mouse models mutated individually at Apc (Apc1638N+/−) or Cdkn1a (Cdkn1a−/−), followed by measurements of protein and gene expression changes in intestinal epithelial tissue. We hypothesized that if the predicted network is biologically coherent (functional), then the predicted nodes should associate more specifically with dysregulated genes and proteins than stochastically selected genes and proteins. The predicted Apc-Cdkn1a network was significantly perturbed at the mRNA-level by both single gene knockouts, and the predictions were also strongly supported based on physical proximity and mRNA coexpression of proteomic targets. These results support the functional coherence of the proposed Apc-Cdkn1a network and also demonstrate how network-based predictions can be statistically tested using high-throughput biological data
Food Insecurity Prevalence Across Diverse Sites During COVID-19: A Year of Comprehensive Data
Key Findings NFACT includes 18 study sites in 15 states as well as a national poll, collectively representing a sample size of more than 26,000 people. Some sites have implemented multiple survey rounds, here we report results from 22 separate surveys conducted during the year since the COVID-19 pandemic began in March 2020. 18 out of 19 surveys in 14 sites with data for before and since the pandemic began found an increase in food insecurity since the start of the COVID-19 pandemic as compared to before the pandemic. In nearly all surveys (18/19) that measured food insecurity both before and during the pandemic, more Black, Indigenous, and People of Color (BIPOC) were classified as food insecure during the pandemic as compared to before it began. Prevalence of food insecurity for BIPOC respondents was higher than the overall population in the majority of surveys (19/20) sampling a general population. In almost all surveys (21/22), the prevalence of food insecurity for households with children was higher than the overall prevalence of food insecurity. Food insecurity prevalence was higher for households experiencing a negative job impact during the pandemic (i.e. job loss, furlough, reduction in hours) in nearly all surveys and study sites (21/22). Food insecurity prevalence in most sites was significantly higher before COVID-19 than estimates from that time period. Reporting a percent change between pre and during COVID-19 prevalence may provide additional information about the rate of change in food insecurity since the start of the pandemic, which absolute prevalence of food insecurity may not capture. Results highlight consistent trends in food insecurity outcomes since the start of the COVID-19 pandemic, across diverse study sites, methodological approaches, and time
The alpha-kinase family: an exceptional branch on the protein kinase tree
The alpha-kinase family represents a class of atypical protein kinases that display little sequence similarity to conventional protein kinases. Early studies on myosin heavy chain kinases in Dictyostelium discoideum revealed their unusual propensity to phosphorylate serine and threonine residues in the context of an alpha-helix. Although recent studies show that some members of this family can also phosphorylate residues in non-helical regions, the name alpha-kinase has remained. During evolution, the alpha-kinase domains combined with many different functional subdomains such as von Willebrand factor-like motifs (vWKa) and even cation channels (TRPM6 and TRPM7). As a result, these kinases are implicated in a large variety of cellular processes such as protein translation, Mg2+ homeostasis, intracellular transport, cell migration, adhesion, and proliferation. Here, we review the current state of knowledge on different members of this kinase family and discuss the potential use of alpha-kinases as drug targets in diseases such as cancer
Change & Maintaining Change in School Cafeterias: Economic and Behavioral-Economic Approaches to Increasing Fruit and Vegetable Consumption
Developing a daily habit of consuming fruits and vegetables (FV) in children is an important public-health goal. Eating habits acquired in childhood are predictive of adolescent and adult dietary patterns. Thus, healthy eating patterns developed early in life can protect the individual against a number of costly health deficits and may reduce the prevalence of obesity. At present, children in the United States (US) under-consume FV despite having access to them through the National School Lunch Program. Because access is an obstacle to developing healthy eating habits, particularly in low-income households, targeting children’s FV consumption in schools has the advantage of near-universal FV availability among more than 30 million US children. This chapter reviews economic and behavioral-economic approaches to increasing FV consumption in schools. Inclusion criteria include objective measurement of FV consumption (e.g., plate waste measures) and minimal demand characteristics. Simple but effective interventions include (a) increasing the variety of vegetables served, (b) serving sliced instead of whole fruits, (c) scheduling lunch after recess, and (d) giving children at least 25 minutes to eat. Improving the taste of FV and short-term incentivizing consumption of gradually increasing amounts can produce large increases in consumption of these foods. Low-cost game-based incentive program may increase the practicality of the latter strategy
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