324 research outputs found
Augmenting Numerical Stability of the Galerkin Finite Element Formulation for Electromagnetic Flowmeter Analysis
The magnetic flow meter is one of the best possible choice for the
measurement of flow rate of liquid metals in fast breeder reactors. Due to the
associated complexities in the measuring environment, theoretical evaluation of
their sensitivity is always preferred. In order to consider the 3D nature of
the problem and the general flow patterns, numerical field computational
approach is inevitable. When classical Galerkin's finite element formulation is
employed for the solution, it is known to introduce numerical oscillations at
high flow rates. The magnetic field produced by the flow induced currents
circulate within the fluid and forms the source of this numerical problem. To
overcome this, modified methods like stream-line upwind Petrov-Galerkin schemes
are generally suggested in the allied areas like fluid dynamics, in which a
similar dominance of advective (curl or circulation) component occurs over
diffusion (divergence) component. After a careful analysis of the numerical
instability through a reduced one dimensional problem, an elegant stable
approach is devised. In this scheme, a pole-zero cancellation approach is
adopted. The proposed scheme is shown to be absolutely stable. However, at
lower flow rates numerical results exhibits small oscillation, which can be
controlled by reducing the element size. The source of stability at higher flow
rates, as well as, oscillations at lower flow rates are analysed using
analytical solution of the associated difference equation. Finally the proposed
approach is applied to the original flow meter problem and the solution is
shown to be stable.Comment: IET Science, Measurement & Technology, 201
The plasma nitric oxide and homocysteine levels and their association with insulin resistance in South Indian women with polycystic ovary syndrome
Background: Women with polycystic ovary syndrome (PCOS) exhibit features of the metabolic syndrome apart from low-grade chronic inflammation and endothelial dysfunction and may be at increased risk for cardiovascular disease (CVD). The Nitric oxide (NO) and Homocysteine (Hcy) are important plasma markers of endothelial dysfunction, an early marker of atherosclerosis. There are no Indian studies on NO and Hcy levels in women with PCOS and their association with Insulin Resistance (IR). Therefore the present study is to estimate plasma levels of NO and Hcy in south Indian women with PCOS and association with insulin resistance.Methods: 104 women with PCOS and 95 healthy age matched control subject were enrolled in the study. Standard physical methods and Chemiluminescent Immunoassay technique were employed for estimation of Anthropometric parameter and plasma sex hormones respectively. Fasting insulin, glucose, NO and Hcy were measured by standard methods. Insulin resistance was evaluated by using Homeostasis Model Assessment for Insulin Resistance (HOMA- IR)Results: Women with PCOS had significantly higher insulin resistance (P<0.01), Hcy (p<0.05) and lower NO levels (P<0.05), IR was positively correlated with Hcy (r= 0.610, p<0.01) and negatively correlated with NO (r= -0.285; p<0.01)Conclusions: Our data revealed that South Indian women with PCOS had elevated IR and homocyeteine and lowered NO levels
Discovery of active enhancers through bidirectional expression of short transcripts
Abstract Background Long-range regulatory elements, such as enhancers, exert substantial control over tissue-specific gene expression patterns. Genome-wide discovery of functional enhancers in different cell types is important for our understanding of genome function as well as human disease etiology. Results In this study, we developed an in silico approach to model the previously reported phenomenon of transcriptional pausing, accompanied by divergent transcription, at active promoters. We then used this model for large-scale prediction of non-promoter-associated bidirectional expression of short transcripts. Our predictions were significantly enriched for DNase hypersensitive sites, histone H3 lysine 27 acetylation (H3K27ac), and other chromatin marks associated with active rather than poised or repressed enhancers. We also detected modest bidirectional expression at binding sites of the CCCTC-factor (CTCF) genome-wide, particularly those that overlap H3K27ac. Conclusions Our findings indicate that the signature of bidirectional expression of short transcripts, learned from promoter-proximal transcriptional pausing, can be used to predict active long-range regulatory elements genome-wide, likely due in part to specific association of RNA polymerase with enhancer regions
Techniques, Tricks and Algorithms for Efficient GPU-Based Processing of Higher Order Hyperbolic PDEs
GPU computing is expected to play an integral part in all modern Exascale
supercomputers. It is also expected that higher order Godunov schemes will make
up about a significant fraction of the application mix on such supercomputers.
It is, therefore, very important to prepare the community of users of higher
order schemes for hyperbolic PDEs for this emerging opportunity. We focus on
three broad and high-impact areas where higher order Godunov schemes are used.
The first area is computational fluid dynamics (CFD). The second is
computational magnetohydrodynamics (MHD) which has an involution constraint
that has to be mimetically preserved. The third is computational
electrodynamics (CED) which has involution constraints and also extremely stiff
source terms. Together, these three diverse uses of higher order Godunov
methodology, cover many of the most important applications areas. In all three
cases, we show that the optimal use of algorithms, techniques and tricks, along
with the use of OpenACC, yields superlative speedups on GPUs! As a bonus, we
find a most remarkable and desirable result: some higher order schemes, with
their larger operations count per zone, show better speedup than lower order
schemes on GPUs. In other words, the GPU is an optimal stratagem for overcoming
the higher computational complexities of higher order schemes! Several avenues
for future improvement have also been identified. A scalability study is
presented for a real-world application using GPUs and comparable numbers of
high-end multicore CPUs. It is found that GPUs offer a substantial performance
benefit over comparable number of CPUs, especially when all the methods
designed in this paper are used.Comment: 73 pages, 17 figure
Evaluation of fatty acid profile with special reference to hypertension intake from marine edible fishes
The present study describes the changes in fatty acid profile in hypertension patients by up taking the marine edible fishes Elutherenema tetradactylum, Sphyraena obtusata and Siganus javus because these marine edible fishes are rich in ? –fatty acids. In this study the total cholesterol, HDL and LDL were significantly decreased from 211.9 – 202.1 mg/dl, 177-159.6 mg/dl. The palmitic acid (C16:0) was found significantly higher in all of peoples compared with other SFAs. This study revealed that the most abundant in individual FAs 16:0,18:0,18:1 n9 and 20:2 n6 were present in blood in both before and after dietary intake. The minimal changes of SFAs levels were decreased averagely from 59.2 to 52.2%. In addition to above PUFAs also increased from 27.7-30.5%. The essential FAs like ALA (C18:3n3), EPA (C20:5n3) and DHA (C22:6n3) were accounting in the range of 2.64-2.92%, 3.67-3.94% and 3.65-4.38%. Omega – 6/3 ratio were recorded from 1.77-2.45%. This study proves the marine edible fishes reduce the hypertension of the patients. Keywords: Edible fishes, ? –fatty acids, SFAs, HDL and LD
Genome-Wide Analysis of Natural Selection on Human Cis-Elements
Background: It has been speculated that the polymorphisms in the non-coding portion of the human genome underlie much of the phenotypic variability among humans and between humans and other primates. If so, these genomic regions may be undergoing rapid evolutionary change, due in part to natural selection. However, the non-coding region is a heterogeneous mix of functional and non-functional regions. Furthermore, the functional regions are comprised of a variety of different types of elements, each under potentially different selection regimes. Findings and Conclusions: Using the HapMap and Perlegen polymorphism data that map to a stringent set of putative binding sites in human proximal promoters, we apply the Derived Allele Frequency distribution test of neutrality to provide evidence that many human-specific and primate-specific binding sites are likely evolving under positive selection. We also discuss inherent limitations of publicly available human SNP datasets that complicate the inference of selection pressures. Finally, we show that the genes whose proximal binding sites contain high frequency derived alleles are enriched for positive regulation of protein metabolism and developmental processes. Thus our genome-scale investigation provide
Differential impact of glucose administered intravenously and orally on circulating mir-375 levels in human subjects
Background: To date, numerous nucleic acid species have been detected in the systemic circulation including microRNAs (miRNAs); however their functional role in this compartment remains unclear. Objective: The aim of this study was to determine whether systemic levels of miRNAs abundant in blood, including the neuroendocrine tissue-enriched miR-375, are altered in response to a glucose challenge. Design: Twelve healthy males were recruited for an acute cross-over study which consisted of two tests each following an eight-hour fasting period. An oral glucose tolerance test (OGTT) was performed and blood samples were collected over a 3-hour period. Following a period of at least one week, the same participants were administered an isoglycemic intravenous glucose infusion (IIGI) with the same blood collection protocol. Results: The glucose response curve following the IIGI mimicked that obtained after the OGTT, but as expected systemic insulin levels were lower during the IIGI compared to the OGTT (P<0.05). MiR-375 levels in circulation were increased only in response to an OGTT and not during an IIGI. In addition, the response to the OGTT also coincided with the transient increase of circulating glucagon-like peptide-1 (GLP-1), glucagon-like peptide-2 (GLP-2), and glucose-dependent insulinotropic polypeptide (GIP). Conclusions: The present findings show levels of miR-375 increase following administration of an OGTT and in light of its enrichment in cells of the gut, suggest that the gastrointestinal tract may play a significant role to the abundance and function of this microRNA in the blood
Transcriptional targets of the schizophrenia risk gene MIR137
Genome-wide association studies (GWAS) have strongly implicated MIR137 (the gene encoding the microRNA miR-137) in schizophrenia. A parsimonious hypothesis is that a pathway regulated by miR-137 is important in the etiology of schizophrenia. Full evaluation of this hypothesis requires more definitive knowledge about biological targets of miR-137, which is currently lacking. Our goals were to expand knowledge of the biology of miR-137 by identifying its empirical targets, and to test whether the resulting lists of direct and indirect targets were enriched for genes and pathways involved in risk for schizophrenia. We overexpressed miR-137 in a human neural stem cell line and analyzed gene expression changes at 24 and 48 h using RNA sequencing. Following miR-137 overexpression, 202 and 428 genes were differentially expressed after 24 and 48 h. Genes differentially expressed at 24 h were enriched for transcription factors and cell cycle genes, and differential expression at 48 h affected a wider variety of pathways. Pathways implicated in schizophrenia were upregulated in the 48 h findings (major histocompatibility complex, synapses, FMRP interacting RNAs and calcium channels). Critically, differentially expressed genes at 48 h were enriched for smaller association P-values in the largest published schizophrenia GWAS. This work provides empirical support for a role of miR-137 in the etiology of schizophrenia
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