1,819 research outputs found

    Periodic gamma-ray emissions from Geminga at or = 10(12) eV

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    Analysis of data from an atmospheric Cerenkov telescope indicated the periodic emission of gamma rays of energy 10 to the 12th power eV, at 60.25 second period, from 2CG 195+4. The gamma ray flux at 99% confidence level is estimated to be 9.5 x 10 to 12 photons/sq cm/s

    Reconstructing promoter activity from Lux bioluminescent reporters

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    The bacterial Lux system is used as a gene expression reporter. It is fast, sensitive and non-destructive, enabling high frequency measurements. Originally developed for bacterial cells, it has also been adapted for eukaryotic cells, and can be used for whole cell biosensors, or in real time with live animals without the need for euthanasia. However, correct interpretation of bioluminescent data is limited: the bioluminescence is different from gene expression because of nonlinear molecular and enzyme dynamics of the Lux system. We have developed a computational approach that, for the first time, allows users of Lux assays to infer gene transcription levels from the light output. This approach is based upon a new mathematical model for Lux activity, that includes the actions of LuxAB, LuxEC and Fre, with improved mechanisms for all reactions, as well as synthesis and turn-over of Lux proteins. The model is calibrated with new experimental data for the LuxAB and Fre reactions from Photorhabdus luminescens --- the source of modern Lux reporters --- while literature data has been used for LuxEC. Importantly, the data show clear evidence for previously unreported product inhibition for the LuxAB reaction. Model simulations show that predicted bioluminescent profiles can be very different from changes in gene expression, with transient peaks of light output, very similar to light output seen in some experimental data sets. By incorporating the calibrated model into a Bayesian inference scheme, we can reverse engineer promoter activity from the bioluminescence. We show examples where a decrease in bioluminescence would be better interpreted as a switching off of the promoter, or where an increase in bioluminescence would be better interpreted as a longer period of gene expression. This approach could benefit all users of Lux technology

    Podophyllum hexandrum Offers Radioprotection by Modulating Free Radical Flux: Role of Aryl-Tetralin Lignans

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    We have evaluated the effect of variation in aryl-tetralin lignans on the radioprotective properties of Podophyllum hexandrum. Two fractionated fractions of P. hexandrum [methanolic (S1) and chloroform fractions (S2)], with varying aryl-tetralin lignan content were utilized for the present study. The peroxyl ion scavenging potentials of S1 and S2 were found to be comparable [i.e. 45.88% (S1) and 41% (S2)] after a 48 h interval in a time-dependent study, whereas in a 2 h study, S2 exhibited significant (P < 0.05) antioxidant activity in different metal ion + flux states. In the aqueous phase, S2 exhibited non-site-specific reactive oxygen species scavenging activity, i.e. 73.12% inhibition at 500 μg ml(−1). S1 exhibited 58.40 ± 0.8% inhibition (at 0.025 μg ml(−1)) of the formation of reactive nitrite radicals, comparable to S2 (52.45 ± 0.825%), and also showed 45.01% site-specific activity (1000 μg ml(−1)), along with significant (P < 0.05) electron donation potential (50–2000 μg ml(−1)) compared to S2. Such activities of S1 could be attributed to the significantly (P < 0.05) higher levels of podophyllotoxin β-d-glucopyranoside (16.5 times) and demethyl podophyllotoxin glucoside (2.9 times) compared with S2. Together, these findings clearly prove that aryl-tetralin lignan content influences the radiation protective potential of the Podophyllum fractions to a great extent

    Bound, virtual and resonance SS-matrix poles from the Schr\"odinger equation

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    A general method, which we call the potential SS-matrix pole method, is developed for obtaining the SS-matrix pole parameters for bound, virtual and resonant states based on numerical solutions of the Schr\"odinger equation. This method is well-known for bound states. In this work we generalize it for resonant and virtual states, although the corresponding solutions increase exponentially when rr\to\infty. Concrete calculations are performed for the 1+1^+ ground and the 0+0^+ first excited states of 14N^{14}\rm{N}, the resonance 15F^{15}\rm{F} states (1/2+1/2^+, 5/2+5/2^+), low-lying states of 11Be^{11}\rm{Be} and 11N^{11}\rm{N}, and the subthreshold resonances in the proton-proton system. We also demonstrate that in the case the broad resonances their energy and width can be found from the fitting of the experimental phase shifts using the analytical expression for the elastic scattering SS-matrix. We compare the SS-matrix pole and the RR-matrix for broad s1/2s_{1/2} resonance in 15F{}^{15}{\rm F}Comment: 14 pages, 5 figures (figures 3 and 4 consist of two figures each) and 4 table

    Association of Reduced Folate Carrier (RFC) Gene Polymorphism with Colorectal Cancer Susceptibility In Kashmir.

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    Folate, important cofactorin one carbon moiety transfer, has been a factor that may modulate the development of colorectal cancer through aberrant DNA methylation and altered nucleotide synthesis and repair. Major folate transport across cell membrane is mediated by reduced folate carrier-1 (RFC1) that also preferably transports chemotherapeutic agents. Variants within the RFC 1 by influencing folate uptake may lead to colorectal cancer susceptibility. Our study is the first to investigate prospectively the RFC gene polymorphism in colorectal cancer in Kashmiri population. A total of 620 subjects (300 colorectal cancer patients and 320 normal subjects) were analyzed by PCR-RFLP technique for RFC gene polymorphism in exon 2 at position 80. We observed 1.27 fold increased risk for AA homozygous variant (OR= 1.27; 95% CI, 0.8678 - 1.875) and 1.19 fold increased risk for GA heterozygous genotypes (OR= 1.19; 95% CI, 0.8080 - 1.760) respectively to CRC susceptibility. However the statistically significant results for smoking and tumor location characteristics were stratified with RFC1 polymorphism, which suggests a possible effect of smoking and cancer location in the etiology of CRC in Kashmir

    Assessment of Wind Power Potential Based on Raleigh Distribution Model: An Experimental Investigation for Coastal Zone

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    When compared with other renewable energy resources (RER), the wind energy share in the global energy production is increasing rapidly. Currently, the Government of Pakistan (GoP) is moving towards RER, specifically wind and solar energy. In this paper, the wind energy potential of Tando Ghulam Ali, Sindh, Pakistan is explored. For this purpose, one-year wind speed data is considered at various heights through various probability distribution functions (PDFs). Statistical comparison of Rayleigh, gamma, generalized extreme value (GEV) and lognormal PDFs have been done with two methods, namely root mean square error and (R^2) in order to select the best PDF. Results showed that the Rayleigh distribution function is the best at the above mentioned area for finding various factors like site selection and wind power cost per kWh

    Mineralocorticoid Receptor Blockade Attenuates Chronic Overexpression of the Renin-Angiotensin- Aldosterone System Stimulation of Reduced Nicotinamide Adenine Dinucleotide Phosphate Oxidase and Cardiac Remodeling

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    doi: 10.1210/en.2006-1691The renin-angiotensin-aldosterone system contributes to cardiac remodeling, hypertrophy, and left ventricular dysfunction. Angiotensin II and aldosterone (corticosterone in rodents) together generate reactive oxygen species (ROS) via reduced nicotinamide adenine dinucleotide phosphate (NADPH) oxidase, which likely facilitate this hypertrophy and remodeling. This investigation sought to determine whether cardiac oxidative stress and cellular remodeling could be attenuated by in vivo mineralocorticoid receptor (MR) blockade in a rodent model of the chronically elevated tissue renin-angiotensin-aldosterone system, the transgenic TG (mRen2) 27 rat (Ren2). The Ren2 overexpresses the mouse renin transgene with resultant hypertension, insulin resistance, proteinuria, and cardiovascular damage. Young (6- to 7-wk-old) male Ren2 and age-matched Sprague-Dawley rats were treated with spironolactone or placebo for 3 wk. Heart tissue ROS, immunohistochemical analysis of 3-nitrotyrosine,and NADPH oxidase (NOX) subunits (gp91phox recently renamed NOX2, p22phox, Rac1, NOX1, and NOX4) were measured. Structural changes were assessed with cine-magnetic resonance imaging, transmission electron microscopy, and light microscopy. Significant increases in Ren2 septal wall thickness (cine-magnetic resonance imaging) were accompanied by perivascular fibrosis, increased mitochondria, and other ultrastructural changes visible by light microscopy and transmission electron microscopy. Although there was no significant reduction in systolic blood pressure, significant improvements were seen with MR blockade on ROS formation and NOX subunits (each P < 0.05). Collectively, these data suggest that MR blockade, independent of systolic blood pressure reduction, improves cardiac oxidative stress-induced structural and functional changes, which are driven, in part, by angiotensin type 1 receptor-mediated increases in NOX.This research was supported by National Institutes of Health (NIH) Grants R01 HL73101-01A1 (to J.R.S.) and P01 HL-51952 (to C.F.), the Veterans Affairs Merit System (0018) (to J.R.S.), and Advanced Research Career Development (to C.S.). Male transgenic Ren2 rats and male Sprague-Dawley controls were kindly provided by C.F. through the Transgenic Core Facility supported in part by NIH Grant HL-51952

    Search for the standard model Higgs boson in the H to ZZ to 2l 2nu channel in pp collisions at sqrt(s) = 7 TeV

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    A search for the standard model Higgs boson in the H to ZZ to 2l 2nu decay channel, where l = e or mu, in pp collisions at a center-of-mass energy of 7 TeV is presented. The data were collected at the LHC, with the CMS detector, and correspond to an integrated luminosity of 4.6 inverse femtobarns. No significant excess is observed above the background expectation, and upper limits are set on the Higgs boson production cross section. The presence of the standard model Higgs boson with a mass in the 270-440 GeV range is excluded at 95% confidence level.Comment: Submitted to JHE

    Measurement of the t t-bar production cross section in the dilepton channel in pp collisions at sqrt(s) = 7 TeV

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    The t t-bar production cross section (sigma[t t-bar]) is measured in proton-proton collisions at sqrt(s) = 7 TeV in data collected by the CMS experiment, corresponding to an integrated luminosity of 2.3 inverse femtobarns. The measurement is performed in events with two leptons (electrons or muons) in the final state, at least two jets identified as jets originating from b quarks, and the presence of an imbalance in transverse momentum. The measured value of sigma[t t-bar] for a top-quark mass of 172.5 GeV is 161.9 +/- 2.5 (stat.) +5.1/-5.0 (syst.) +/- 3.6(lumi.) pb, consistent with the prediction of the standard model.Comment: Replaced with published version. Included journal reference and DO
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