1,164 research outputs found

    On the Weakening of Chromospheric Magnetic Field in Active Regions

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    Simultaneous measurement of line-of-sight (LOS) magnetic and velocity fields at the photosphere and chromosphere are presented. Fe I line at λ6569\lambda6569 and HαH_{\alpha} at λ6563\lambda6563 are used respectively for deriving the physical parameters at photospheric and chromospheric heights. The LOS magnetic field obtained through the center-of-gravity method show a linear relation between photospheric and chromospheric field for field strengths less than 700 G. But in strong field regions, the LOS magnetic field values derived from HαH_{\alpha} are much weaker than what one gets from the linear relationship and also from those expected from the extrapolation of the photospheric magnetic field. We discuss in detail the properties of magnetic field observed in HαH_{\alpha} from the point of view of observed velocity gradients. The bisector analysis of HαH_{\alpha} Stokes II profiles show larger velocity gradients in those places where strong photospheric magnetic fields are observed. These observations may support the view that the stronger fields diverge faster with height compared to weaker fields.Comment: accepted for publication in Ap

    Drosophila adult muscle development and regeneration

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    Myogenesis is a highly orchestrated, complex developmental process by which cell lineages that are mesodermal in origin generate differentiated multinucleate muscle cells as a final product. Considerable insight into the process of myogenesis has been obtained for the embryonic development of the larval muscles of Drosophila. More recently, the postembryonic development of the muscles of the adult fly has become a focus of experimental investigation of myogenesis since specific flight muscles of the fly manifest remarkable similarities to vertebrate muscles in their development and organization. In this review, we catalog some of the milestones in the study of myogenesis in the large adult-specific flight muscles of Drosophila. The identification of mesoderm-derived muscle stem cell lineages, the characterization of the symmetric and asymmetric divisions through which they produce adult-specific myoblasts, the multifaceted processes of myoblast fusion, and the unexpected discovery of quiescent satellite cells that can be activated by injury are discussed. Moreover, the finding that all of these processes incorporate a plethora of signaling interactions with other myogenic cells and with niche-like neighboring tissue is considered. Finally, we briefly point out possible future developments in the area of Drosophila myogenesis that may lead to of new avenues of genetic research into the roles of muscle stem cells in development, disease and aging

    Electrochemical heavy metal detection, photocatalytic, photoluminescence, biodiesel production and antibacterial activities of Ag�ZnO nanomaterial

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    Zinc oxide nanoparticles (ZnO Nps) and silver doped zinc oxide nanoparticles (Ag�ZnO Nps) were prepared using nitrates of zinc and silver as oxidizers and succinic acid as a fuel through solution combustion synthesis (SCS) at 400 °C. The synthesized materials were characterized by various analytical techniques such as XRD, FTIR, Raman UV�vis, PL, SEM, EDX and TEM. The synthesized nanomaterials were tested for the photocatalytic degradation of methylene blue and the result reveal that Ag�ZnO Nps shows the better photocatalytic activity compared to undoped ZnO Nps. Biodiesel production from Simarouba oil shows that Ag�ZnO Nps acts as good catalyst compare to ZnO Nps, we have also developed sensor which showed a linearity in the concentration range 50�350 nM and limit of detection was found to be 3.5 and 3.8 nM (3�) for lead and cadmium respectively. Further we have examined the antibacterial activity against Escherichia coli and Staphylococcus aureus bacteria. © 2017 Elsevier Lt

    Experiences with Mycobacterium leprae soluble antigens in a leprosy endemic population

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    Rees and Convit antigens prepared from armadillo-derived Mycobacterium leprae were used for skin testing in two leprosy endemic villages to understand their use in the epidemiology of leprosy. In all, 2602 individuals comprising 202 patients with leprosy detected in a prevalence survey, 476 household contacts and 1924 persons residing in non-case households were tested with two antigens. There was a strong and positive correlation ( r = 0.85) between reactions to the Rees and Convit antigens. The distribution of reactions was bimodal and considering reactions of 12 mm or more as ‘positive’, the positivity rate steeply increased with the increase in age. However. the distributions of reactions to these antigens in patients with leprosy. their household contacts and persons living in non-case households were very similar. These results indicate that Rees and Convit antigens are not useful in the identification of M. leprae infection or in the confirmation of leprosy diagnosis in a leprosy endemic population with a high prevalence of nonspecific sensitivity

    Achromatizing a liquid-crystal spectropolarimeter: Retardance vs Stokes-based calibration of HiVIS

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    Astronomical spectropolarimeters can be subject to many sources of systematic error which limit the precision and accuracy of the instrument. We present a calibration method for observing high-resolution polarized spectra using chromatic liquid-crystal variable retarders (LCVRs). These LCVRs allow for polarimetric modulation of the incident light without any moving optics at frequencies >10Hz. We demonstrate a calibration method using pure Stokes input states that enables an achromatization of the system. This Stokes-based deprojection method reproduces input polarization even though highly chromatic instrument effects exist. This process is first demonstrated in a laboratory spectropolarimeter where we characterize the LCVRs and show example deprojections. The process is then implemented the a newly upgraded HiVIS spectropolarimeter on the 3.67m AEOS telescope. The HiVIS spectropolarimeter has also been expanded to include broad-band full-Stokes spectropolarimetry using achromatic wave-plates in addition to the tunable full-Stokes polarimetric mode using LCVRs. These two new polarimetric modes in combination with a new polarimetric calibration unit provide a much more sensitive polarimetric package with greatly reduced systematic error.Comment: Accepted in PAS

    Vibrational Analysis in Condition Monitoring and faults Diagnosis of Rotating Shaft - Over View

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    Rotating shaft is a vital element in power stations like Gas power stations, steam power station and Tidal power stations. These shaft failure or break down lead to the consequences, ranges from annoyance to the financial disaster or human damage. Hence predictive maintenance which includes early detection, identification and correction of machinery problems is paramount to anyone involved in the maintenance of industrial machinery to insure continued, safe and productive operation. Condition monitoring of machines is become necessary to run the machines efficiently. Vibrations are caused due to unbalance in the rotating components, dry friction between the two mating surfaces, misalignments, imperfect of coupling or bearings, and cracks in the shafts or blades. In predictive maintenance, vibration monitoring and analysis is essential. Health of any rotating shaft can be identified by its signature includes number of peaks. The peaks in the spectrum or signature give the information regarding the type of fault. In this paper gives a overview on vibrations analysis and faults diagnosis in various rotating machine parts and also this paper attempts to epitomize the recent research and developments in rotating element vibration analysis techniques

    "Of Mice and Measures": A Project to Improve How We Advance Duchenne Muscular Dystrophy Therapies to the Clinic

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    A new line of dystrophic mdx mice on the DBA/2J (D2) background has emerged as a candidate to study the efficacy of therapeutic approaches for Duchenne muscular dystrophy (DMD). These mice harbor genetic polymorphisms that appear to increase the severity of the dystropathology, with disease modifiers that also occur in DMD patients, making them attractive for efficacy studies and drug development. This workshop aimed at collecting and consolidating available data on the pathological features and the natural history of these new D2/mdx mice, for comparison with classic mdx mice and controls, and to identify gaps in information and their potential value. The overall aim is to establish guidance on how to best use the D2/mdx mouse model in preclinical studies

    On the warm pool dynamics in the southeastern Arabian Sea during April - May 2005 based on the satellite remote sensing and ARGO float data

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    Observational data from the Arabian Sea Monsoon Experiment (ARMEX-Phase IIA) in the southeastern Arabian Sea (SEAS) showed intense warming with the SST up to 31.5°C during April-May 2005. Analysis of 5-day repeat cycles of temperature and salinity profiles from an ARGO float (ID No. 2900345) in a 3°x1° box closer to ARMEX-II buoy (8.3°N, 72.68°E) in the SEAS during January-September 2005 revealed evolution of warm pool (SST>28°C) in spring 2005. The Argo data derived D20 (depth of 20°C isotherm) showed the influence of remote forcing during January-May, and local wind forcing during southwest monsoon. Low salinity waters (<34.0) occupied the top 30 m during January-February followed by temperature inversions (up to 0.5°C) in the 30-60 m depth range. From the peak spring warming, the SST dropped gradually by 3.5°C by end-July with the advent of southwest monsoon followed by a decrease in net heat gain upto 100 W/m^2. The merged weekly products of sea surface height anomalies and the NLOM simulated surface currents showed complex surface circulation consisting of seasonal Lakshadweep High/Low in winter/summer. The examined oceanic and atmospheric variables showed an intraseasonal variability with 41 to 63 day period, coinciding with the Madden-Julian Oscillatio

    Update on Standard Operating Procedures in Preclinical Research for DMD and SMA Report of TREAT-NMD Alliance Workshop, Schiphol Airport, 26 April 2015, The Netherlands

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    A workshop took place in 2015 to follow up TREAT-NMD activities dedicated to improving quality in the preclinical phase of drug development for neuromuscular diseases. In particular, this workshop adressed necessary future steps regarding common standard experimental protocols and the issue of improving the translatability of preclinical efficacy studies

    Impact of pulp rheology on selective recovery of value minerals from ores

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    Rheological behavior of mineral pulps plays a critical role in almost all mineral processing unit operations. Although the impact of rheology in unit operations such as grinding and slurry transport has received much attention in the past, this is not the case for flotation. The pathway by which the pulp rheology influences the flotation performance is not well understood. The aim of this paper is to explore how physical (shape, size and morphology) and surface chemical properties of minerals contribute to pulp rheology and pathways by which rheology can influence selective value mineral recovery and/or concentrate grade. Systematic studies involving spiking experiments (deliberate addition of fibrous minerals and other solids), measurement of pulp viscosity and yield stress, flotation tests, SEM, EDX and XRD were conducted on a Ni ore and a Cu ore. A phenomenological model was developed. The key components of the model are the formation of a macro-network comprising micro-aggregates of fibrous minerals which significantly increases pulp viscosity, and as a result impedes gas dispersion and bubble-particle attachment and influence froth phase properties. Additionally, the role of various reagent types in regulating pulp rheological behavior was explored
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