1,622 research outputs found

    Compactness and asymptotic behavior in nonautonomous linear parabolic equations with unbounded coefficients in Rd\R^d

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    We consider a class of second order linear nonautonomous parabolic equations in R^d with time periodic unbounded coefficients. We give sufficient conditions for the evolution operator G(t,s) be compact in C_b(R^d) for t>s, and describe the asymptotic behavior of G(t,s)f as t-s goes to infinity in terms of a family of measures mu_s, s in R, solution of the associated Fokker-Planck equation

    Field-dependent heat transport in the Kondo insulator SmB6 : phonons scattered by magnetic impurities

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    The thermal conductivity κ\kappa of the Kondo insulator SmB6_6 was measured at low temperature, down to 70 mK, in magnetic fields up to 15 T, on single crystals grown using both the floating-zone and the flux methods. The residual linear term κ0/T\kappa_0/T at T→0T \to 0 is found to be zero in all samples, for all magnetic fields, in agreement with previous studies. There is therefore no clear evidence of fermionic heat carriers. In contrast to some prior data, we observe a large enhancement of κ(T)\kappa(T) with increasing field. The effect of field is anisotropic, depending on the relative orientation of field and heat current (parallel or perpendicular), and with respect to the cubic crystal structure. We interpret our data in terms of heat transport predominantly by phonons, which are scattered by magnetic impurities.Comment: publish versio

    The Observers' Data Access Portal at the Keck Observatory Archive

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    For all active instruments, the Keck Observatory Archive (KOA) now ingests raw data from the Keck Telescopes within 1 minute of acquisition, quick-look reduced data within 5 minutes of creation, and science ready reduced data for four instruments as they are created by their automated pipelines. On August 1, 2023, KOA released the Observers Data Access Portal (ODAP), which enables observers at the telescope and their collaborators anywhere in the world to securely monitor and download science, calibration, and quick-look data as they are ingested into the archive. The portal is built using Python Socket IO.WebSockets that ensure metadata appear in the portal as the data themselves are ingested. The portal itself is a dynamic web interface built with React. It enables users to view and customize metadata fields, filter metadata according to data type, and download data as they are ingested or in bulk through wget scripts. Observers have used the ODAP since its release and have provided feedback that will guide future releases.Comment: 4 pages, 2 figs, ADASS 2024 proceeding

    Renal Dysfunction Criteria in Critically Ill Children: The PODIUM Consensus Conference

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    CONTEXT Renal dysfunction is associated with poor outcomes in critically ill children. OBJECTIVE To evaluate the current evidence for criteria defining renal dysfunction in critically ill children and association with adverse outcomes. To develop contemporary consensus criteria for renal dysfunction in critically ill children. DATA SOURCES PubMed and Embase were searched from January 1992 to January 2020. STUDY SELECTION Included studies evaluated critically ill children with renal dysfunction, performance characteristics of assessment tools for renal dysfunction, and outcomes related to mortality, functional status, or organ-specific or other patient-centered outcomes. Studies with adults or premature infants (≤36 weeks' gestational age), animal studies, reviews, case series, and studies not published in English with inability to determine eligibility criteria were excluded. DATA EXTRACTION Data were extracted from included studies into a standard data extraction form by task force members. RESULTS The systematic review supported the following criteria for renal dysfunction: (1) urine output <0.5 mL/kg per hour for ≥6 hours and serum creatinine increase of 1.5 to 1.9 times baseline or ≥0.3 mg/dL, or (2) urine output <0.5 mL/kg per hour for ≥12 hours, or (3) serum creatinine increase ≥2 times baseline, or (4) estimated glomerular filtration rate <35 mL/minute/1.73 m2, or (5) initiation of renal replacement therapy, or (6) fluid overload ≥20%. Data also support criteria for persistent renal dysfunction and for high risk of renal dysfunction. LIMITATIONS All included studies were observational and many were retrospective. CONCLUSIONS We present consensus criteria for renal dysfunction in critically ill children
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