310 research outputs found

    Chiral plasma instability and primordial Gravitational wave

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    It is known that cosmic magnetic field, if present, can generate anisotropic stress in the plasma and hence, can act as a source of gravitational waves. These cosmic magnetic fields can be generated at very high temperature, much above electroweak scale, due to the gravitational anomaly in presence of the chiral asymmetry. The chiral asymmetry leads to instability in the plasma which ultimately leads to the generation of magnetic fields. In this article, we discuss the generation of gravitational waves, during the period of instability, in the chiral plasma sourced by the magnetic field created due to the gravitational anomaly. We have shown that such gravitational wave will have a unique spectrum. Moreover, depending on the temperature of the universe at the time of its generation, such gravitational waves can have a wide range of frequencies. We also estimate the amplitude and frequency of the gravitational waves and delineate the possibility of its detection by future experiments like eLISA.Comment: 8 pages, 2 figure

    Extreme Case of Spectral Band Difference Correction Between the OSIRIS-REX-NAVCAM2 and DSCOVR-EPIC Imagers

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    Earth-viewed images acquired during a recent asteroid intercept mission present a unique opportunity for radiometric calibration of visible imagers onboard a space exploration probe. Measurements from the CERES consistent DSCOVR-EPIC imager act as a reference in providing spatially, temporally, and angularly matched radiance values for deriving OSIRIS-REx-NavCam sensor calibration gains. The calibration is accomplished using an optimized all-sky tropical ocean ray-matching technique, which employs complex pixel remapping, navigation correction, and angular geometry consideration. Of critical consideration in this specific inter-calibration event is the extreme difference in spectral response function (SRF) width between the NavCam and EPIC imagers, which could cause a rather large bias. The NASA-LaRC SCIAMACHY based online spectral band adjustment factor (SBAF) calculation tool provides an empirical solution to such potential spectral-difference-induced biases through a high spectral- resolution hyper spectral convolution approach. The adjustments produced from this tool can effectively reduce the calibration gain bias of NavCam2 by nearly 6%, thereby adjusting the NavCam2 sensor to within 3.2% of its prelaunch calibration. These results highlight the capability of the SBAF tool to account for exceptionally disparate SRFs

    Character association and path analysis for yield and its related traits in finger millet (Eleusine coracana (L.) Gaertn) genotypes

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    The present investigation was conducted during Kharif, 2014 at Research Block, Department of Crop Improvement, College of Forestry, Ranichauri Campus, V.C.S.G. Uttarakhand University of Horticulture and Forestry. The thirty-five diverse genotypes of finger millet, Eleusine coracana (L.) including three checks viz., PRM-1, PRM-2 and VL-149 laid out in Randomized Complete Block Design with replication. The data on 14 quantitative traits viz., days to 50 per cent flowering, days to maturity, plant height (cm), flag leaf area (cm2), peduncle length (cm), number of leaves on main culm, number of productive tillers per plant, number of fingers per ear, finger length (cm), ear length (cm), biological yield per plant (g), harvest index (%), 1000 seed weight, grain yield per plant (g) were collect-ed randomly from 5 plants form each genotypes. Analysis of variance revealed highly significant differences among all thirty five genotypes with a wide range of mean values for different characters. Grain yield per plant exhibited very strong positive association with biological yield per plant (0.6196, 0.6805), harvest index (0.4370, 0.3624), number of productive tillers per plant (0.3950, 0.4477), 1000 seed weight (0.3697, 0.3972) and peduncle length (0.2473, 0.2694) at phenotypic and genotypic level. Path-coefficient analysis indentified biological yield per plant (0.8983, 1.1590) and harvest index (0.7390, 0.9162) as major direct contributors towards grain yield per plant at phenotypic and genotypic level. The characters identified above merit due consideration in formulating effective selection strategy in finger millet for developing high yielding varieties

    Cross-Calibration of AQUA-MODIS and NPP-VIIRS Reflective Solar Bands for a Seamless Record of CERES Cloud and Flux Properties

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    The CERES measured shortwave and longwave fluxes rely on the cloud properties derived using the coincident observations from the accompanying high-resolution MODIS and VIIRS imagers. The calibration consistency is required between MODIS and VIIRS radiances to ensure that the CERES provided cloud property retrievals are temporally consistent. This paper presents multiple approaches of cross-calibrating the spectrally comparable reflective solar bands (RSB) of Aqua-MODIS and NPP- VIIRS, and estimates the radiometric biases for individual band pair. The inter-comparison is performed between the Aqua-MODIS collection 6.1 level 1B and NPP-VIIRS Land PEATE V1 datasets. Radiometric biases up to 3% were estimated bet een the MODIS and VIIRS radiances for visible bands

    Enhancements to the Open Access Spectral Band Adjustment Factor Online Calculation Tool for Visible Channels

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    With close to 40 years of satellite observations, from which, cloud, land-use, and aerosol parameters can be measured, inter-consistent calibrations are needed to normalize retrievals across satellite records. Various visible-sensor inter-calibration techniques have been developed that utilize radiometrically stable Earth targets, e.g., deep convective clouds and desert/polar ice pseudo-invariant calibration sites. Other equally effective, direct techniques for intercalibration between satellite imagers are simultaneous nadir overpass comparisons and ray-matched radiance pairs. Combining independent calibration results from such varied techniques yields robust calibration coefficients, and is a form of self-validation. One potential source of significant error when cross-calibrating satellite sensors, however, are the often small but substantial spectral discrepancies between comparable bands, which must be accounted for. As such, visible calibration methods rely on a Spectral Band Adjustment Factor (SBAF) to account for the spectral-response function- induced radiance differences between analogous imagers. The SBAF is unique to each calibration method as it is a function of the Earth-reflected spectra. In recent years, NASA Langley pioneered the use of SCIAMACHY-, GOME-2-, and Hyperion-retrieved Earth spectra to compute SBAFs. By carefully selecting hyperspectral footprints that best represent the conditions inherent to an inter-calibration technique, the uncertainty in the SBAF is greatly reduced. NASA Langley initially provided the Global Space-based Inter-calibration System processing and research centers with online SBAF tools, with which users select conditions to best match their calibration criteria. This article highlights expanded SBAF tool capabilities for visible wavelengths, with emphasis on the use of the spectral range filtering for the purpose of separating scene conditions for the channel that the SBAF is needed based on the reflectance values of other bands. In other words, spectral filtering will enable better scene-type selection for bands where scene determination is difficult without information from other channels, which should prove valuable to users in the calibration community

    Viscosity in cosmic fluids

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    The effective theory of large-scale structure formation based on Λ\LambdaCDM paradigm predicts finite dissipative effects in the resulting fluid equations. In this work, we study how viscous effect that could arise if one includes self-interaction among the dark-matter particles combines with the effective theory. It is shown that these two possible sources of dissipation can operate together in a cosmic fluid and the interplay between them can play an important role in determining dynamics of the cosmic fluid. In particular, we demonstrate that the viscosity coefficient due to self-interaction is added inversely with the viscosity calculated using effective theory of Λ\LambdaCDM model. Thus the larger viscosity has less significant contribution in the effective viscosity. Using the known bounds on σ/m\,\sigma/m for self-interacting dark-matter, where σ\,\sigma\, and mm are the cross-section and mass of the dark-matter particles respectively, we discuss role of the effective viscosity in various cosmological scenarios.Comment: 7 pages, Updated to match with the published versio

    Senior citizens and over the counter drugs: challenges in rural India

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    Background: The geriatric population is on a rise in India, which is accompanied by an increase in their health care needs. As they are prone to have multiple diseases simultaneously the tendency for over the counter (OTC) or non-prescription drugs is much higher among the elderly population. A thorough knowledge about the medication practices among elderly is indispensable since the chances for adverse drugs events; drug interactions etc. are higher among them. The primary objective of the present study was to measure the prevalence of over the counter drug usage among those aged 60 years or above residing in a rural block of North Tamilnadu, India.Methods: A community based cross sectional study was conducted among those aged 60 years or above using an interviewer administered questionnaire and data was collected from 100 consenting participants who were selected using multi stage sampling.Results: The prevalence of the usage of over the counter drugs among the elderly population was found to be 51% (95% CI 41.1-60.9). It was shown that the usage of OTC drugs was associated with higher socio economic status (p value 0.015) and literacy (p value 0.003).Conclusions: Further studies need to done to identify whether such high prevalence of OTC drug usage among elderly is a reflection of drug practices among general population and if proven otherwise should explore the various reasons for the same so that necessary measures can be implemented to alleviate the situation.

    Assessment of Antioxidant Properties in Fruits of Myrica esculenta: A Popular Wild Edible Species in Indian Himalayan Region

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    Crude extract of Myrica esculenta fruits, a wild edible species of Indian Himalayan Region, was evaluated for phenolic compounds and antioxidant properties. Results revealed significant variation in total phenolic and flavonoid contents across populations. Among populations, total phenolic content varied between 1.78 and 2.51 mg gallic acid equivalent/g fresh weight (fw) of fruits and total flavonoids ranged between 1.31 and 1.59 mg quercetin equivalent/g fw. Antioxidant activity determined by 2,2′-azinobis(3-ethylbenzothiazoline-6-sulphonic acid) radical scavenging, 1,1-diphenyl-2-picrylhydrazyl radical scavenging and ferric reducing antioxidant power (FRAP) exhibited considerable antioxidant potential and showed significant positive correlation with total phenolic and total flavonoids content. High performance liquid chromatography analysis revealed significant variation (P <  .01) in phenolic compounds (i.e., gallic acid, catechin, hydroxybenzioc acid and ρ-coumaric acid) across populations. This study provides evidences to establish that consumption of M. esculenta fruits while providing relished taste would also help in reduction of free radicals. Therefore, this wild edible species deserves promotion in the region through horticulture and forestry interventions

    The Characterization of Deep Convective Cloud Albedo as a Calibration Target Using MODIS Reflectances

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    There are over 25 years of historical satellite data available to climate analysis. The historical satellite data needs to be well calibrated, especially in the visible, where there is no onboard calibration on operational satellites. The key to the vicarious calibration of historical satellites relies on invariant targets, such as the moon, Dome C, and deserts. Deep convective clouds (DCC) also show promise of being a stable invariant or predictable target viewable by all satellites, since they behave as solar diffusers. However DCC have not been well characterized for calibration. Ten years of well-calibrated MODIS is now available. DCC can easily be identified using IR thresholds, where the IR calibration can be traced to the onboard black-bodies. The natural variability of DCC albedo will be analyzed geographically and seasonally, especially difference of convection initiated over land or ocean. Functionality between particle size and ozone absorption with DCC albedo will be examined. Although DCC clouds are nearly Lambertion, the angular distribution of reflectances will be sampled and compared with theoretical models. Both Aqua and Terra MODIS DCC angular models will be compared for consistency. Normalizing angular geostationary DCC reflectances, which were calibrated against MODIS, with SCIAMACHY spectral reflectances and comparing them to MODIS DCC reflectances will inspect the usage of DCC albedos as an absolute calibration target
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