3,283 research outputs found

    Electroconvective instability in a fluid layer

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    Electroconvective instabilities in fluid laye

    Anti-CTLA-4 (CD 152) monoclonal antibody-induced autoimmune interstitial nephritis

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    Targeted immune-modulating agents are entering clinical practice in many specialties, providing novel therapeutic possibilities but introducing new potential toxicities. We present the first reported case, to our knowledge, of immune-mediated nephritis following the administration of Tremelimumab (CP-675, 206), an anti-cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4) monoclonal antibody. High-dose steroid therapy led to a rapid improvement in renal function, avoiding the need for renal replacement therapy.Peer reviewe

    Thermodiffusion in model nanofluids by molecular dynamics simulations

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    In this work, a new algorithm is proposed to compute single particle (infinite dilution) thermodiffusion using Non-Equilibrium Molecular Dynamics simulations through the estimation of the thermophoretic force that applies on a solute particle. This scheme is shown to provide consistent results for simple Lennard-Jones fluids and for model nanofluids (spherical non-metallic nanoparticles + Lennard-Jones fluid) where it appears that thermodiffusion amplitude, as well as thermal conductivity, decrease with nanoparticles concentration. Then, in nanofluids in the liquid state, by changing the nature of the nanoparticle (size, mass and internal stiffness) and of the solvent (quality and viscosity) various trends are exhibited. In all cases the single particle thermodiffusion is positive, i.e. the nanoparticle tends to migrate toward the cold area. The single particle thermal diffusion 2 coefficient is shown to be independent of the size of the nanoparticle (diameter of 0.8 to 4 nm), whereas it increases with the quality of the solvent and is inversely proportional to the viscosity of the fluid. In addition, this coefficient is shown to be independent of the mass of the nanoparticle and to increase with the stiffness of the nanoparticle internal bonds. Besides, for these configurations, the mass diffusion coefficient behavior appears to be consistent with a Stokes-Einstein like law

    Conceptual Design of a High-Resolution, Low Cost Topographic Mapping Mission

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    There is a need for space-based topographic mapping missions which are an order-of-magnitude less costly than the 100M−classmissionscurrentlyplannedbyNASAandthecommercialcommunity.TheStereoImagingLong−LookSatellite(STILLSAT),havingamassofapproximately100kg,isdesignedfor5minstantaneousfieldofview(IFOV)tomeetmostofthetopographicrequirementsofboththescienceandcartographycommunity.TheresultingDigitalElevationModels(DEM)arepredictedtohave10m(absolute)contourintervals,geo−correctedbygrounddatum.FrameandpanoramiccamerasfromApollo15,16,and17,aswellasESA2˘7sMetricCamerasandtheU.S.LargeFormatCamerahavebeencitedbyphotogrammetristsasadvantageousfortopographicmapproduction.TheuseofaCCDframingcameraforstereoimagingwasdiscussedbyJPLin1979butdismissedbecauseCCDtechnologywasnotyetmatureenough.BycapitalizingonrecentadvancesinCCDtechnologyandinstitutingaconceptofsharedstabilityandpointingresponsibilitybetweenthebusandpayload,itisnowpossibletoconsidersuchanadvancedmission.Thispaperwillfocusonthesystemengineeringtradesresultingfrommissionrequirementsthatdictateearth/satellitemotioncompensationtoachieveveryhighspatialresolution,aswellasoff−axiscrosstrackimagingtomaximizetargetacquisition.Themissionisapproachedfromanintegrateddesignparadigmwhereinscience,instrument,bus,andgroundoperationsobjectivesaresimultaneouslyweighedtoachieveextremelylowcost,lowpower,andreliablemissionelements.TheinitialSTILLSATmissionoperationsplanistoobtainmultiplestereoimagesatbaseheightratiosof1.0withintargets−of−opportunityof100kmindiametertosupportspecificscienceobjectives.STILLSATisdesignedforline−of−sightpointingtowithin0.1degreeandcanimageoff−axisupto20degreesinthecrosstrackdirection.Thetotalspacecraftandmissionoperationscostisexpectedtobewellunder100M-class missions currently planned by NASA and the commercial community. The Stereo Imaging Long-Look Satellite (STILLSAT), having a mass of approximately 100 kg, is designed for 5m instantaneous field of view (IFOV) to meet most of the topographic requirements of both the science and cartography community. The resulting Digital Elevation Models (DEM) are predicted to have 10m (absolute) contour intervals, geo-corrected by ground datum. Frame and panoramic cameras from Apollo 15, 16, and 17, as well as ESA\u27s Metric Cameras and the U.S. Large Format Camera have been cited by photogrammetrists as advantageous for topographic map production. The use of a CCD framing camera for stereo imaging was discussed by JPL in 1979 but dismissed because CCD technology was not yet mature enough. By capitalizing on recent advances in CCD technology and instituting a concept of shared stability and pointing responsibility between the bus and payload, it is now possible to consider such an advanced mission. This paper will focus on the system engineering trades resulting from mission requirements that dictate earth/satellite motion compensation to achieve very high spatial resolution, as well as off-axis cross track imaging to maximize target acquisition. The mission is approached from an integrated design paradigm wherein science, instrument, bus, and ground operations objectives are simultaneously weighed to achieve extremely low cost, low power, and reliable mission elements. The initial STILLSAT mission operations plan is to obtain multiple stereo images at base height ratios of 1.0 within targets-of-opportunity of 100km in diameter to support specific science objectives. STILLSAT is designed for line-of-sight pointing to within 0.1 degree and can image off-axis up to 20 degrees in the cross track direction. The total spacecraft and mission operations cost is expected to be well under 5M (not including launch) and is being initially proposed as a Student Explorer Development Initiative (STEDI) project to the Universities Space Research Association\u27s Advanced Design Program. A launch could occur within 24 months of go-ahead. Progressively advanced concepts of this approach will be discussed, those which can map much larger regions of the Earth through use of larger detector arrays and mosaicked images. It is even conceivable that a STILLSAT-derived single global mapping satellite or constellation of simpler satellites could provide worldwide coverage. This approach holds promise for both scientific and commercial applications

    Identification of Seismo-Volcanic Regimes at Whakaari/White Island (New Zealand) Via Systematic Tuning of an Unsupervised Classifier

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    We present an algorithm based on Self-Organizing Maps (SOM) and k-means clustering to recognize patterns in a continuous 12.5-year tremor time series recorded at Whakaari/White Island volcano, New Zealand (hereafter referred to as Whakaari). The approach is extendable to a variety of volcanic settings through systematic tuning of the classifier. Hyperparameters are evaluated by statistical means, yielding a combination of “ideal” SOM parameters for the given data set. Extending from this, we applied a Kernel Density Estimation approach to automatically detect changes within the observed seismicity. We categorize the Whakaari seismic time series into regimes representing distinct volcano-seismic states during recent unrest episodes at Whakaari (2012/2013, 2016, and 2019). There is a clear separation in classification results between background regimes and those representing elevated levels of unrest. Onset of unrest is detected by the classifier 6 weeks before the August 2012 eruption, and ca. 3.5 months before the December 2019 eruption, respectively. Regime changes are corroborated by changes in commonly monitored tremor proxies as well as with reported volcanic activity. The regimes are hypothesized to represent diverse mechanisms including: system pressurization and depressurization, degassing, and elevated surface activity. Labeling these regimes improves visualization of the 2012/2013 and 2019 unrest and eruptive episodes. The pre-eruptive 2016 unrest showed a contrasting shape and nature of seismic regimes, suggesting differing onset and driving processes. The 2016 episode is proposed to result from rapid destabilization of the shallow hydrothermal system, while rising magmatic gases from new injections of magma better explain the 2012/2013 and 2019 episodes

    Demonstration of the Zero-Crossing Phasemeter with a LISA Test-bed Interferometer

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    The Laser Interferometer Space Antenna (LISA) is being designed to detect and study in detail gravitational waves from sources throughout the Universe such as massive black hole binaries. The conceptual formulation of the LISA space-borne gravitational wave detector is now well developed. The interferometric measurements between the sciencecraft remain one of the most important technological and scientific design areas for the mission. Our work has concentrated on developing the interferometric technologies to create a LISA-like optical signal and to measure the phase of that signal using commercially available instruments. One of the most important goals of this research is to demonstrate the LISA phase timing and phase reconstruction for a LISA-like fringe signal, in the case of a high fringe rate and a low signal level. We present current results of a test-bed interferometer designed to produce an optical LISA-like fringe signal previously discussed in the literature.Comment: find minor corrections in the CQG versio

    PREPARATION, CHARACTERIZATION, AND OPTIMIZATION OF MEBENDAZOLE SPHERICAL AGGLOMERATES USING MODIFIED EVAPORATIVE PRECIPITATION IN AQUEOUS SOLUTION (EPAS)

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    Objective: Mebendazole is a popular benzimidazole class anthelmintic drug useful in the treatment of main infections of threadworms as well as other less common worm infections like whipworm, roundworm, and hookworm in adults and children over 2 y of age. It is poorly soluble in water resulting in poor absorption from the intestinal tract leading to a decrease in bioavailability. Moreover, Mebendazole has poor flowability due to the needle-shaped crystals. This work was carried out with the aim of increasing the flowability and solubility of Mebendazole. Methods: A 32 full factorial design was used to investigate the effect of the concentration of Mebendazole and the quantity of water as an external phase using evaporative precipitation into an aqueous solution. The prepared agglomerates were characterized for particle size distribution, shape, Hausner ratio, Carr’s index and % dissolved in 60 min (C60).   Results: The prepared agglomerates were found to be monodispersed. They also showed a decrease in the Hausner ration and Carr’s index, indicating improved flowability. Increase in C60 indicated that the agglomerates were found to have increased water solubility. Conclusion: Scanning Electron Microscopy showed that the agglomerates were spherical in shape. Fourier Transformed Infra-Red studies showed no chemical change in the prepared spherical agglomerates. Differential Scanning Calorimetry and X-ray diffraction studies showed an increase in amorphous characteristics of prepared spherical agglomerates. This method may be used for drugs with similar characteristics as Mebendazole

    High Resolution HST-STIS Spectra of CI and CO in the Beta Pictoris Circumstellar Disk

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    High resolution FUV echelle spectra showing absorption features arising from CI and CO gas in the Beta Pictoris circumstellar (CS) disk were obtained on 1997 December 6 and 19 using the Space Telescope Imaging Spectrograph (STIS). An unsaturated spin-forbidden line of CI at 1613.376 A not previously seen in spectra of Beta Pictoris was detected, allowing for an improved determination of the column density of CI at zero velocity relative to the star (the stable component), N = (2-4) x 10^{16} cm^{-2}. Variable components with multiple velocities, which are the signatures of infalling bodies in the Beta Pictoris CS disk, are observed in the CI 1561 A and 1657 A multiplets. Also seen for the first time were two lines arising from the metastable singlet D level of carbon, at 1931 A and 1463 A The results of analysis of the CO A-X (0-0), (1-0), and (2-0) bands are presented, including the bands arising from {13}^CO, with much better precision than has previously been possible, due to the very high resolution provided by the STIS echelle gratings. Only stable CO gas is observed, with a column density N(CO) = (6.3 +/- 0.3) x 10^{14} cm{-2}. An unusual ratio of the column densities of {12}^CO to {13}^CO is found (R = 15 +/- 2). The large difference between the column densities of CI and CO indicates that photodissociation of CO is not the primary source of CI gas in the disk, contrary to previous suggestion.Comment: 13 pages, including 6 figures. LaTex2e (emulateapj5.sty). Accepted for publication in Ap

    Science with the World Space Observatory - Ultraviolet

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    The World Space Observatory-Ultraviolet (WSO-UV) will provide access to the UV range during the next decade. The instrumentation on board will allow to carry out high resolution imaging, high sensitivity imaging, high resolution (R~55000) spectroscopy and low resolution (R~2500) long slit spectroscopy. In this contribution, we briefly outline some of the key science issues that WSO-UV will address during its lifetime. Among them, of special interest are: the study of galaxy formation and the intergalactic medium; the astronomical engines; the Milky Way formation and evol ution, and the formation of the Solar System and the atmospheres of extrasolar p lanets.Comment: Just one text file (aigomezdecastro.tex). To be published in the proceeding of the conference: "New Quest in Stellar Astrophysics II: UV properties of evolved stellar populations" held in Puerto Vallarta - Mexico, in april 200
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