388 research outputs found

    Correcting C-band radar reflectivity and differential reflectivity data for rain attenuation: a self-consistent method with constraints

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    Includes bibliographical references.Quantitative use of C-band radar measurements of reflectivity (Zh) and differential reflectivity (Zdr) demands the use of accurate attenuation-correction procedures, especially in convective rain events. With the availability of differential phase measurements (Φdp) with a dual-polarized radar, it is now possible to improve and stabilize attenuation-correction schemes over earlier schemes which did not use Φdp. The recent introduction of constraint-based correction schemes using Φdp constitute an important advance [8], [9]. In this paper, a self-consistent, constraint-based algorithm is proposed and evaluated which extends the previous approaches in several important respects. Radar data collected by the C-POL radar during the South China Sea Monsoon Experiment (SCSMEX) are used to illustrate the correction scheme. The corrected radar data are then compared against disdrometer-based scattering simulations, the disdrometer data being acquired during SCSMEX. A new algorithm is used to retrieve the median volume diameter from the corrected Zh, corrected Zdr, and Kdp radar measurements which is relatively immune to the precise drop axis ratio versus drop diameter relation. Histograms of the radar-retrieved Do compared against Do from disdrometer data are in remarkable good agreement lending further validity to the proposed attenuation-correction scheme, as well as to confidence in the use of C-band radar for the remote measurement of rain microphysics.The work of V. N. Bringi and V. Chandrasekar was supported by the NASA/TRMM Grant NAG5-7717 and -7876

    The Final State of Black Strings and p-Branes, and the Gregory-Laflamme Instability

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    It is shown that the usual entropy argument for the Gregory-Laflamme (GL) instability for somesome appropriate black strings and pp-branes gives surprising agreement up to a few percent. This may provide a strong support to the GL's horizon fragmentation, which would produce the array of higher-dimensional Schwarzschild-type's black holes finally. On the other hand, another estimator for the size of the black hole end-state relative to the compact dimension indicates a second order (i.e., smooth) phase transition for some otherother appropriate compactifications and total dimension of spacetime wherein the entropy argument is not appropriate. In this case, Horowitz-Maeda-type's non-uniform black strings or pp-branes can be the final state of the GL instability.Comment: More emphasis on a second order phase transition. The computation result is unchange

    Crptography based Lifi for Patient Privacy and Emergency Health Service Using IOT

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    Medical care is one such region, where WIFI is as yet not utilized as the electromagnetic waves influences patients with sicknesses like neurological problems, diseases and so forth. Accordingly, LIFI can be respected the following large thing, as it represents no gamble to patients and offers more advantages than WIFI, such as faster speeds and a larger spectrum. The only issue that hospitals have while exchanging data through it is ensuring confidentiality. The methodology proposed here leverages Secure Hash Algorithms to give maximum security as a solution to this challenge. The Secure Hash Algorithm is a bonus feature that is mostly utilised for authentication. IoT connects physical devices such as sensors and actuators to networks. The programming routines can be visualised from any location thanks to cloud storage. These algorithms can be employed in a variety of applications, including smart homes, digital technologies, and banking systems. This research presents a model that takes into account a human's heart rate, glucose level, and temperature. In the even to fan emergency, adjacent hospitals are alerted to the patient's condition, allowing them to provide timely and correct care. This will save you from having to go to the hospital. Temperature, blood pressure, heart rate, gas sensor, and fall detection are among the vital signs monitored by the system. An Arduino controller and a GSM900Amodule make up the system design. The monitored values can be supplied via mobile phones, and if an abnormal state is detected, the buzzer is activated, and the information is communicated to the concerned members via the mobile app

    Evaluation of the Quality of Commercial Fish Feeds in India with Respect to Microbiological Parameters

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    This paper describes the first comprehensive study of the quality of commercial fish feeds in India with regard to microbiological indices. Quality of feed is an important parameter that has a direct impact on the outcome of any aquaculture system. Microbiological parameters such as total plate count (TPC), Escherichia coli (CFUg-1), coliformes (CFUg-1), Enterobacteriaceae (CFUg-1) and yeast and mould (CFUg-1) counts were analysed using 3M™ Petrifilm™ as per guidelines. The TPC ranged from 2.0 × 102 to3.13 × 104 CFUg-1 in different feeds. Presence of E. coli was detected in one of the feeds with 1.15×102 CFUg-1. Coliform bacteria were not detected in any of the feeds. Enterobacteriaceae was present in three feeds in the range of 5.45 × 102 to 1.58×103 CFUg-1. Yeast and mould count ranged from <10 to 1.68 × 104 CFUg-1 in the feeds analyzed. The results obtained from the present study indicate that the feeds were contaminated with micro-organisms. As far as Indian scenario is concerned, there exist several feed companies which do not comply with the quality regulations and specifications as laid down by the Bureau of Indian Standards (BIS). In addition, specifications are not available for aqua feeds regarding the acceptable levels of microbiological parameters. Hence the present study calls for a standardized code of quality to be observed by feed manufacturing companies for quality products

    Persistent currents in diffusive metallic cavities: Large values and anomalous scaling with disorder

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    The effect of disorder on confined metallic cavities with an Aharonov-Bohm flux line is addressed. We find that, even deep in the diffusive regime, large values of persistent currents may arise for a wide variety of geometries. We present numerical results supporting an anomalous scaling law of the average typical current with the strength of disorder ww, wγ \sim w^{- \gamma} with γ<2\gamma < 2. This is contrasted with previously reported results obtained for cylindrical samples where a scaling w2 \sim w^{-2} has been found. Possible links to, up to date, unexplained experimental data are finally discussed.Comment: 5 pages, 4 figure

    Lie families: theory and applications

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    We analyze families of non-autonomous systems of first-order ordinary differential equations admitting a common time-dependent superposition rule, i.e., a time-dependent map expressing any solution of each of these systems in terms of a generic set of particular solutions of the system and some constants. We next study relations of these families, called Lie families, with the theory of Lie and quasi-Lie systems and apply our theory to provide common time-dependent superposition rules for certain Lie families.Comment: 23 pages, revised version to appear in J. Phys. A: Math. Theo

    Nonsingular 2-D Black Holes and Classical String Backgrounds

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    We study a string-inspired classical 2-D effective field theory with {\it nonsingular} black holes as well as Witten's black hole among its static solutions. By a dimensional reduction, the static solutions are related to the (SL(2,R)kU(1))/U(1)(SL(2,R)_{k}\otimes U(1))/U(1) coset model, or more precisely its O((α)0)O\bigl((\alpha')^{0}\bigr) approximation known as the 3-D charged black string. The 2-D effective action possesses a propagating degree of freedom, and the dynamics are highly nontrivial. A collapsing shell is shown to bounce into another universe without creating a curvature singularity on its path, and the potential instability of the Cauchy horizon is found to be irrelevent in that some of the infalling observers never approach the Cauchy horizon. Finally a SL(2,R)k/U(1)SL(2,R)_{k}/U(1) nonperturbative coset metric, found and advocated by R. Dijkgraaf et.al., is shown to be nonsingular and to coincide with one of the charged spacetimes found above. Implications of all these geometries are discussed in connection with black hole evaporation.Comment: 30 pages with 2 figures, harvmac, CALT-68-1852 (Discussions on the gravitational collapse of thin shells in a charged spacetime are clarified. Two extra references.

    Direct visualization reveals dynamics of a transient intermediate during protein assembly

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    Interactions between proteins underlie numerous biological functions. Theoretical work suggests that protein interactions initiate with formation of transient intermediates that subsequently relax to specific, stable complexes. However, the nature and roles of these transient intermediates have remained elusive. Here, we characterized the global structure, dynamics, and stability of a transient, on-pathway intermediate during complex assembly between the Signal Recognition Particle (SRP) and its receptor. We show that this intermediate has overlapping but distinct interaction interfaces from that of the final complex, and it is stabilized by long-range electrostatic interactions. A wide distribution of conformations is explored by the intermediate; this distribution becomes more restricted in the final complex and is further regulated by the cargo of SRP. These results suggest a funnel-shaped energy landscape for protein interactions, and they provide a framework for understanding the role of transient intermediates in protein assembly and biological regulation

    Current-spin-density functional study of persistent currents in quantum rings

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    We present a numerical study of persistent currents in quantum rings using current spin density functional theory (CSDFT). This formalism allows for a systematic study of the joint effects of both spin, interactions and impurities for realistic systems. It is illustrated that CSDFT is suitable for describing the physical effects related to Aharonov-Bohm phases by comparing energy spectra of impurity-free rings to existing exact diagonalization and experimental results. Further, we examine the effects of a symmetry-breaking impurity potential on the density and current characteristics of the system and propose that narrowing the confining potential at fixed impurity potential will suppress the persistent current in a characteristic way.Comment: 7 pages REVTeX, including 8 postscript figure

    Temporal Experiment for Storms and Tropical Systems Technology Demonstration (TEMPEST-D) Mission: Enabling Time-Resolved Cloud and Precipitation Observations from 6U-Class Satellite Constellations

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    The Temporal Experiment for Storms and Tropical Systems Technology Demonstration (TEMPEST-D) mission is to demonstrate the capability of 6U-Class satellite constellations to perform repeat-pass radiometry to measure clouds and precipitation with high temporal resolution on a global basis. The TEMPEST mission concept is to improve understanding of clouds and precipitation by providing critical information on their time evolution in different climatic regimes. Measuring at five frequencies from 89 to 182 GHz, TEMPEST-D millimeter-wave radiometers are capable of penetrating into the cloud to observe changes as precipitation begins or ice accumulates inside the storm. The TEMPEST-D flight model radiometer instrument has been completed, passed functional testing, vibration testing and self-compatibility testing with the XB1 spacecraft bus. The next steps for the TEMPEST-D millimeter-wave radiometer are thermal vacuum testing and antenna pattern measurements. The complete TEMPEST-D flight system will be delivered to NanoRacks for launch integration in the autumn of 2017, in preparation for launch to the ISS in the second quarter of 2018, with deployment shortly thereafter into a nominal orbit at 400-km altitude and 51.6° inclination
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