23,119 research outputs found

    Intermediate electron transport in Porphyridium: EPR studies

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    Measurement of photosynthetic electron transport in Porphyridium by EPR electron paramagnetic resonanc

    Analyses of earth radiation budget data from unrestricted broadband radiometers on the ESSA 7 satellite

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    Six months of data from the wide-field-of-view low resolution infrared radiometers on the Environmental Science Services Administration (ESSA) 7 satellite were analyzed. Earth emitted and earth reflected irradiances were computed at satellite altitude using data from a new in-flight calibration technique. Flux densitites and albedos were computed for the top of the earth's atmosphere. Monthly averages of these quantities over 100 latitude zones, each hemisphere, and the globe are presented for each month analyzed, and global distributions are presented for typical months. Emitted flux densities are generally lower and albedos higher than those of previous studies. This may be due, in part, to the fact that the ESSA 7 satellite was in a 3 p.m. Sun-synchronous orbit and some of the comparison data were obtained from satellites in 12 noon sun-synchronous orbits. The ESSA 7 detectors seem to smooth out spatial flux density variations more than scanning radiometers or wide-field-of-view fixed-plate detectors. Significant longitudinal and latitudinal variations of emitted flux density and albedo were identified in the tropics in a zone extending about + or - 25 deg in latitude

    Giving up crime: directions for policy

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    Describes eight principles for supporting desistance in criminal justice

    Approaches for modeling magnetic nanoparticle dynamics

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    Magnetic nanoparticles are useful biological probes as well as therapeutic agents. There have been several approaches used to model nanoparticle magnetization dynamics for both Brownian as well as N\'eel rotation. The magnetizations are often of interest and can be compared with experimental results. Here we summarize these approaches including the Stoner-Wohlfarth approach, and stochastic approaches including thermal fluctuations. Non-equilibrium related temperature effects can be described by a distribution function approach (Fokker-Planck equation) or a stochastic differential equation (Langevin equation). Approximate models in several regimes can be derived from these general approaches to simplify implementation

    Oscillatory approach to the singularity in vacuum T2T^2 symmetric spacetimes

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    A combination of qualitative analysis and numerical study indicates that vacuum T2T^2 symmetric spacetimes are, generically, oscillatory.Comment: 2 pages submitted to the Ninth Marcel Grossmann Proceedings; v2, "all known cases" changed to "various known cases" in the first paragrap

    RXTE and BeppoSAX Observations of MCG -5-23-16: Reflection From Distant Cold Material

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    We examine the spectral variability of the Seyfert 1.9 galaxy MCG -5-23-16 using RXTE and BeppoSAX observations spanning 2 years from April 1996 to April 1998. During the first year the X-ray source brightens by a factor of ~25% on timescales of days to months. During this time, the reprocessed continuum emission seen with RXTE does not respond measurably to the continuum increase. However, by the end of the second year during the BeppoSAX epoch the X-ray source has faded again. This time, the reprocessed emission has also faded, indicating that the reprocessed flux has responded to the continuum. If these effects are caused by time delays due to the distance between the X-ray source and the reprocessing region, we derive a light crossing time of between ~1 light day and ~1.5 light years. This corresponds to a distance of 0.001 pc to 0.55 pc, which implies that the reprocessed emission originates between 3x10^15 cm and 1.6x10^18 cm from the X-ray source. In other words, the reprocessing in MCG -5-23-16 is not dominated by the inner regions of a standard accretion disk.Comment: Accepted for publication in ApJ. 17 pages, 8 figure

    On the area of the symmetry orbits in T2T^2 symmetric spacetimes

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    We obtain a global existence result for the Einstein equations. We show that in the maximal Cauchy development of vacuum T2T^2 symmetric initial data with nonvanishing twist constant, except for the special case of flat Kasner initial data, the area of the T2T^2 group orbits takes on all positive values. This result shows that the areal time coordinate RR which covers these spacetimes runs from zero to infinity, with the singularity occurring at R=0.Comment: The appendix which appears in version 1 has a technical problem (the inequality appearing as the first stage of (52) is not necessarily true), and since the appendix is unnecessary for the proof of our results, we leave it out. version 2 -- clarifications added, version 3 -- reference correcte

    UXperimentation: The Library as Design Studio

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    The university and seminary’s work and workplaces evolve within emerging digital ecologies, such as mobile communication, digital fabrication, and cloud hosting. At Abilene Christian University (ACU) in Abilene, TX, we have driven this transformation of educational spaces and curriculum with 1-to-1 and BYOD smartphone and tablet initiatives, and through construction of an interdisciplinary makerspace. Now our provision of personalized access to Adobe Creative Cloud for all students and faculty is again reorienting library spaces and practices with a focus on User Experience (UX). This paper explores: 1) the relation of UXD to library research and instruction. 2) an ecology for UXD and other design thinking in university academic support services, and 3) a trajectory beyond computer labs, media studios, and digital scholarship centers as library learning space

    The Singularity in Generic Gravitational Collapse Is Spacelike, Local, and Oscillatory

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    A longstanding conjecture by Belinskii, Khalatnikov, and Lifshitz that the singularity in generic gravitational collapse is spacelike, local, and oscillatory is explored analytically and numerically in spatially inhomogeneous cosmological spacetimes. With a convenient choice of variables, it can be seen analytically how nonlinear terms in Einstein's equations control the approach to the singularity and cause oscillatory behavior. The analytic picture requires the drastic assumption that each spatial point evolves toward the singularity as an independent spatially homogeneous universe. In every case, detailed numerical simulations of the full Einstein evolution equations support this assumption.Comment: 7 pages includes 4 figures. Uses Revtex and psfig. Received "honorable mention" in 1998 Gravity Research Foundation essay contest. Submitted to Mod. Phys. Lett.
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