53,491 research outputs found

    Polarimetry with a soft x-ray spectrometer

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    An approach for measuring linear X-ray polarization over a broad-band using conventional spectroscopic optics is described. A set of multilayer-coated flats reflect the dispersed X-rays to the instrument detectors. The intensity variation as a function of energy and position angle is measured to determine three Stokes parameters: I, Q, and U. By laterally grading the multilayer optics and matching the dispersion of the gratings, one may take advantage of high multilayer reflectivities and achieve modulation factors over 80% over the entire 0.2 to 0.8 keV band. A sample design is shown that could be used with a small orbiting mission.Comment: Accepted for publication in the proceedings of the SPIE, volume 701

    Ready Educators Quality Improvement Pilot: Linking Program Improvement to Child Outcomes

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    This report is an evaluation of the first year of the Ready Educators Quality Improvement Pilot (REQIP), part of Thrive in 5's city-wide Ready Educators strategy. The pilot provided technical assistance and support to early education and care programs in centers and family child care homes that serve children from birth to age five. The REQIP theory of change posits that, to meet the goal of improved child outcomes, programs need to build "sustainable independent capacity to operationalize a continuous quality improvement process (CQI)." As the Pilot was envisioned, CQI involved the development of a Program Improvement Plan (PIP) through an assessment based on child-level and program data and with support from a Quality Improvement Partner (QIP). The PIP would then serve as the basis for technical assistance to meet the goals of the PIP, followed by a re-assessment using program and childlevel data. This CQI process would be sustained over time, in an ongoing continuous loop. In July 2013, after a competitive RFP process and with funding from the Barr Foundation, Thrive in 5 selected Wellesley Centers for Women to serve as the QIP

    Insolubilized enzymes for food synthesis

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    Cellulose matrix with numerous enzyme-coated silica particles of colloidal size permanently bound at various sites within matrix was produced that has high activity and possesses requisite physical characteristics for filtration or column operations. Product also allows coupling step in synthesis of edible food to proceed under mild conditions

    Updating the Chandra HETGS Efficiencies using In-Orbit Observations

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    The efficiencies of the gratings in the High Energy Transmission Grating Spectrometer (HETGS) were updated using in-flight observations of bright continuum sources. The procedure first involved verifying that fluxes obtained from the +1 and -1 orders match, which checks that the contaminant model and the CCD quantum efficiencies agree. Then the fluxes derived using the high energy gratings (HEGs) were compared to those derived from the medium energy gratings (MEGs). The flux ratio was fit to a low order polynomial, which was allocated to the MEGs above 1 keV or the HEGs below 1 keV. The resultant efficiencies were tested by examining fits to blazar spectra.Comment: 10 pages, 7 figures; to appear in the SPIE proceedings, volume 844

    Dielectric Constant of Liquids (Fluids) Shown to be Simple Fundamental Relation of Density over Extreme Ranges from - 50^o^ to + 600^o^C, Believed Universal

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    Examinations of past complex theoretical equations describing isothermal dielectric constants (_[epsilon]_) of liquids show that none describe experiments throughout and that only a two-constant equation of density is required. The dielectric susceptibility (_[epsilon]_ – 1) as a simple exponential function of density is shown here to describe _[epsilon]_ for both polar and non-polar organic liquids over all available experimental ranges from 0.50 to 1.2 g cm^-3^ and temperatures to 400^o^C. For water above 0.25 g cm^-3^, the equation describes the excellent dielectric-constant formulation of Fernández, et al., (1997) throughout its experimental range [-35 to +600^o^C; to 1000 MPa (10000 Atm)] and even when diluted by "inert" solvents (Marshall, 2008). At lower densities at all temperatures, water susceptibilities converge to an even more simple unit proportionality to density below 0.003 g cm^-3^, not yet verified for organics without experiment. While the past Born, Tait, Clausius-Mossotti, and Owen-Brinkley theories describe _[epsilon]_ equally well over a limited 10% change in density, all are shown to fail over greater ranges. The simple density relation presented here should be useful in clarifying and reducing complexity of theory applied to liquid structure

    Enzymatic regeneration of adenosine triphosphate cofactor

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    Regenerating adenosine triphosphate (ATP) from adenosine diphosphate (ADP) by enzymatic process which utilizes carbamyl phosphate as phosphoryl donor is technique used to regenerate expensive cofactors. Process allows complex enzymatic reactions to be considered as candidates for large-scale continuous processes

    A Soft X-ray Polarimeter Designed for Broad-band X-ray Telescopes

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    A novel approach for measuring linear X-ray polarization over a broad-band using conventional imaging optics and cameras is described. A new type of high efficiency grating, called the critical angle transmission grating is used to disperse soft X-rays radially from the telescope axis. A set of multilayer-coated paraboloids re-image the dispersed X-rays to rings in the focal plane. The intensity variation around these rings is measured to determine three Stokes parameters: I, Q, and U. By laterally grading the multilayer optics and matching the dispersion of the gratings, one may take advantage of high multilayer reflectivities and achieve modulation factors over 50% over the entire 0.2 to 0.8 keV band. A sample design is shown that could be used with the Constellation-X optics.Comment: 11 pages, 7 figures, presented at conference 6688 of the SPI
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