166 research outputs found

    Photosynthetic Efficiency of Microalgae and Cyanobacteria on Reduced Graphene Oxide (RGO) Anode Surface for Utilization in Bio-Photovoltaics (BPV)

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    Bio-photovoltaics (BPV) is sustainable energy production technology that utilize photosynthetic organisms and convert it into electricity. This Study has been carried out to study the photosynthetic efficiency of three microalgae on a Reduced Graphene Oxide (RGO) anode surface. RGO, with its exceptional electrical conductivity and large surface area, presents an attractive platform for enhancing the performance of BPV systems. The work aims to investigate the combined effect of microalgae and RGO anodes for use in BPV technology. RGO was synthesized and characterized on which Chlorella vulgaris, Gloeocapsa and Synechocystis were allowed to grow. A model BPV system was assembled, incorporating the microalgae and cyanobacteria as photoactive agents and RGO as the anode surface. The system was subjected to different experimental condition and photosynthetic efficiency, current generation, and power output were collected and analysed. Results demonstrated a significant improvement in the photosynthetic activity of microalgae when cultured on the RGO anode surface. Chlorella Shows maximum Efficiency in terms of growth and current generation. Statistical analysis confirmed the reliability and significance of these findings. Our finding bridges a crucial knowledge gap in the field of BPV, highlighting the potential of microalgae-RGO systems for cleaner energy production

    Mapping of Thar Desert Grasslands Using High Resolution Carto-Data (A Case Study of Jodhpur District)

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    The spatio-temporal condition and trend of grasslands in India at village-level is still not known completely. Historical and contemporary monitoring and assessment protocols are primarily based on the wisdom, knowledge and experience of village-level revenue officer (patwari) which is just significant from the statistical point of view. Contrastingly, such grassland areas are considered to be of high priority by government authorities for the long-term conservation of biodiversity. Protection, development and sustainable use of grasslands are very important for the rural economy and livestock. The major grasslands now survive west of isohyets 200 to 250 mm rainfall where livestock population is more than human beings. Animal husbandry plays such an important role in the lifestyle and economics of the inhabitants, scientific management of the grasslands, on which the animals depend for nourishment, is totally neglected. Pastoralism has coexisted within dry lands for decades. The constant pressure from an increasing human population and anthropogenic activities, particularly mining, has caused considerable damage to this unique desert grassland ecosystem. Several important grasslands have been converted to agricultural fields and the pressure to convert more grassland into such uses is mounting. Area under grasslands in the Jodhpur district has declined very sharply. It was 6.4% in 1976 (Sen, 1978) but has been reduced to \u3c 1.5% of the district area. Grasslands are one of the important classes of land use mapping exercise. The aim of the present project was to identify and map all grasslands and grazing areas in the Jodhpur district using spectral signatures of 2012-13 high resolution satellite data of Cartosat LISS-IV plus PAN merged and compare with 1976-77 and 2005-06 data. There is a need to sustain and conserve grasslands at grassroots level because these are the important life-supporting mechanism of the dry region. There is an immediate scope for the spatial and temporal scale dependence of assessment tools for grassland monitoring and undertaking research at village-to district-scales to incorporate geographic information systems and satellite remote sensing data, as well as new ecological concepts from landscape ecology and complex systems science

    Land Surface Characterization for Identification and Assessment of Potential Grazing Lands in Arid Western Rajasthan, India

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    Grazing lands (non-arable terrestrial ecosystems) play a vital role in the rural economy and environmental conservation. Modern tools in which, GIS, GPS and satellite remote sensing play vital role in the assessment, characterization and management of grazinglands (Paul et al., 2010). The present study aims to assess the physical conditions and distribution pattern of permanent pastures and other grazing lands in arid Rajasthan using remote sensing and GIS techniques. Though grazing lands do occur in a number of habitats, the study has focused on those sites which have water resources for its rational utilization for pasture/grassland development. Rapid advances in the areas of Remote Sensing, Earth Observations systems, data processing techniques and applications have facilitated users for a better understanding of terrain. One of the recent trends in remote sensing is its application in the extraction of terrain related parameters using large scale mapping and DEM generation. GIS and IRS data are used in inventory, assessment, characterization and management of grazinglands and estimation of forage production & supply-demand balance sheets (Singh et al., 1997)

    Small-scale cosmic ray anisotropy observed by the GRAPES-3 experiment at TeV energies

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    GRAPES-3 is a mid-altitude (2200 m) and near equatorial (11.411.4^{\circ} North) air shower array, overlapping in its field of view for cosmic ray observations with experiments that are located in Northern and Southern hemispheres. We analyze a sample of 3.7×1093.7\times10^9 cosmic ray events collected by the GRAPES-3 experiment between 1 January 2013 and 31 December 2016 with a median energy of 16\sim16 TeV for study of small-scale (<60<60^{\circ}) angular scale anisotropies. We observed two structures labeled as A and B, deviate from the expected isotropic distribution of cosmic rays in a statistically significant manner. Structure `A' spans 5050^{\circ} to 8080^{\circ} in the right ascension and 15-15^{\circ} to 3030^{\circ} in the declination coordinate. The relative excess observed in the structure A is at the level of (6.5±1.3)×104(6.5\pm1.3)\times10^{-4} with a statistical significance of 6.8 standard deviations. Structure `B' is observed in the right ascension range of 110110^{\circ} to 140140^{\circ}. The relative excess observed in this region is at the level of (4.9±1.4)×104(4.9\pm1.4)\times10^{-4} with a statistical significance of 4.7 standard deviations. These structures are consistent with those reported by Milagro, ARGO-YBJ, and HAWC. These observations could provide a better understanding of the cosmic ray sources, propagation and the magnetic structures in our Galaxy

    Clinical features and outcomes of patients with tubercular uveitis treated with antitubercular therapy in the collaborative ocular tuberculosis study (COTS)-1

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    IMPORTANCE Eradication of systemic tuberculosis (TB) has been limited by neglected populations and the HIV pandemic. Whereas ocular TB often presents as uveitis without any prior evidence of systemic TB, the existing uncertainty in the diagnosis of TB uveitis may perpetuate missed opportunities to address systemic TB. OBJECTIVE To examine the clinical features of TB uveitis and the associations with response to antitubercular therapy (ATT). DESIGN, SETTING, AND PARTICIPANTS This retrospective multinational cohort study included patients from 25 ophthalmology referral centers diagnosed with TB uveitis and treated with ATT from January 1, 2004, through December 31, 2014, with a minimum follow-up of 1 year. MAIN OUTCOMES AND MEASURES Treatment failure, defined as a persistence or recurrence of inflammation within 6 months of completing ATT, inability to taper oral corticosteroids to less than 10mg/d or topical corticosteroid drops to less than 2 drops daily, and/or recalcitrant inflammation necessitating corticosteroid-sparing immunosuppressive therapy. RESULTS A total of 801 patients (1272 eyes) were studied (mean [SD] age, 40.5 [14.8] years; 413 [51.6%] male and 388 [48.4%] female; 577 [73.6%] Asian). Most patients had no known history (498 of 661 [75.3%]) of systemic TB. Most patients had bilateral involvement (471 of 801 [58.8%]). Common clinical signs reported include vitreous haze (523 of 1153 [45.4%]), retinal vasculitis (374 of 874 [42.8%]), and choroidal involvement (419 of 651 [64.4%]). Treatment failure developed in 102 of the 801 patients (12.7%). On univariate regression analysis, the hazard ratios (HRs) associated with intermediate uveitis (HR, 2.21; 95%CI, 1.07-4.55; P = .03), anterior uveitis (HR, 2.68; 95%CI, 1.32-2.35; P = .006), and panuveitis (HR, 3.28; 95%CI, 1.89-5.67; P &lt; .001) were significantly higher compared with posterior distribution. The presence of vitreous haze had a statistically significant association (HR, 1.95; 95%CI, 1.26-3.02; P = .003) compared with absence of vitreous haze. Bilaterality had an associated HR of 1.50 (95%CI, 0.96-2.35) compared with unilaterality (HR, 1 [reference]), although this finding was not statistically significant (P = .07). On multivariate Cox proportional hazards regression analysis, the presence of vitreous haze had an adjusted HR of 2.98 (95%CI, 1.50-5.94; P = .002), presence of snow banking had an adjusted HR of 3.71 (95%CI, 1.18-11.62; P = .02), and presence of choroidal involvement had an adjusted HR of 2.88 (95%CI, 1.22-6.78; P = .02). CONCLUSIONS AND RELEVANCE A low treatment failure rate occurred in patients with TB uveitis treated with ATT. Phenotypes and test results are studied whereby patients with panuveitis having vitreous and choroidal involvement had a higher risk of treatment failure. These findings are limited by retrospectivemethods. A prospectively derived composite clinical risk score might address this diagnostic uncertainty through holistic and standardized assessment of the combinations of clinical features and investigation results that may warrant diagnosis of TB uveitis and treatment with ATT

    Study on cosmogenic activation above ground for the DarkSide-20k project

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    The activation of materials due to the exposure to cosmic rays may become an important background source for experiments investigating rare event phenomena. DarkSide-20k is a direct detection experiment for galactic dark matter particles, using a two-phase liquid argon time projection chamber filled with 49.7 tonnes (active mass) of Underground Argon (UAr) depleted in 39Ar. Here, the cosmogenic activity of relevant long-lived radioisotopes induced in the argon and other massive components of the set-up has been estimated; production of 120 t of radiopure UAr is foreseen. The expected exposure above ground and production rates, either measured or calculated, have been considered. From the simulated counting rates in the detector due to cosmogenic isotopes, it is concluded that activation in copper and stainless steel is not problematic. Activation of titanium, considered in early designs but not used in the final design, is discussed. The activity of 39Ar induced during extraction, purification and transport on surface, in baseline conditions, is evaluated to be 2.8% of the activity measured in UAr from the same source, and thus considered acceptable. Other products in the UAr such as 37Ar and 3H are shown to not be relevant due to short half-life and assumed purification methods

    Measurement of isotopic separation of argon with the prototype of the cryogenic distillation plant Aria for dark matter searches

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    The Aria cryogenic distillation plant, located in Sardinia, Italy, is a key component of the DarkSide-20k experimental program for WIMP dark matter searches at the INFN Laboratori Nazionali del Gran Sasso, Italy. Aria is designed to purify the argon, extracted from underground wells in Colorado, USA, and used as the DarkSide-20k target material, to detector-grade quality. In this paper, we report the first measurement of argon isotopic separation by distillation with the 26&nbsp;m tall Aria prototype. We discuss the measurement of the operating parameters of the column and the observation of the simultaneous separation of the three stable argon isotopes: 36Ar , 38Ar , and 40Ar . We also provide a detailed comparison of the experimental results with commercial process simulation software. This measurement of isotopic separation of argon is a significant achievement for the project, building on the success of the initial demonstration of isotopic separation of nitrogen using the same equipment in 2019

    Directionality of nuclear recoils in a liquid argon time projection chamber

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    The direct search for dark matter in the form of weakly interacting massive particles (WIMP) is performed by detecting nuclear recoils (NR) produced in a target material from the WIMP elastic scattering. A promising experimental strategy for direct dark matter search employs argon dual-phase time projection chambers (TPC). One of the advantages of the TPC is the capability to detect both the scintillation and charge signals produced by NRs. Furthermore, the existence of a drift electric field in the TPC breaks the rotational symmetry: the angle between the drift field and the momentum of the recoiling nucleus can potentially affect the charge recombination probability in liquid argon and then the relative balance between the two signal channels. This fact could make the detector sensitive to the directionality of the WIMP-induced signal, enabling unmistakable annual and daily modulation signatures for future searches aiming for discovery. The Recoil Directionality (ReD) experiment was designed to probe for such directional sensitivity. The TPC of ReD was irradiated with neutrons at the INFN Laboratori Nazionali del Sud, and data were taken with 72 keV NRs of known recoil directions. The direction-dependent liquid argon charge recombination model by Cataudella et al. was adopted and a likelihood statistical analysis was performed, which gave no indications of significant dependence of the detector response to the recoil direction. The aspect ratio R of the initial ionization cloud is estimated to be 1.037 +/- 0.027 and the upper limit is R < 1.072 with 90% confidence levelComment: 20 pages, 10 figures, submitted to Eur. Phys. J.

    Sensitivity projections for a dual-phase argon TPC optimized for light dark matter searches through the ionization channel

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    Dark matter lighter than 10 GeV/c2^2 encompasses a promising range of candidates. A conceptual design for a new detector, DarkSide-LowMass, is presented, based on the DarkSide-50 detector and progress toward DarkSide-20k, optimized for a low-threshold electron-counting measurement. Sensitivity to light dark matter is explored for various potential energy thresholds and background rates. These studies show that DarkSide-LowMass can achieve sensitivity to light dark matter down to the solar neutrino floor for GeV-scale masses and significant sensitivity down to 10 MeV/c2^2 considering the Migdal effect or interactions with electrons. Requirements for optimizing the detector's sensitivity are explored, as are potential sensitivity gains from modeling and mitigating spurious electron backgrounds that may dominate the signal at the lowest energies
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