13,125 research outputs found

    Introduction to the Infrared Space Observatory (ISO)

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    The Infrared Space Observatory (ISO) is an astronomical satellite, which will operate at infrared wavelengths (2.5 to 200 microns) for a period of at least 18 months. Imaging, spectroscopic, photometric and polarimetric observations will be obtained by four scientific instruments in the focal plane of its 60-cm diameter, cryogenically-cooled telescope. Two-thirds of ISO's observing time will be available to the astronomical community. ISO is a fully approved and funded project of the European Space Agency (ESA) with a foreseen launch date of May 1993

    A cryogenically-cooled Fabry-Perot interferometer for balloon infrared astronomy

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    Imperial Users onl

    A Generalization of the Brodsky-Lepage Formalism

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    We present an approach that generalizes in a natural way the perturbative QCD formalism developed by Brodsky and Lepage for the study of exclusive hadronic processes to the case of L≠0L\neq 0 mesons. As an application of our approach we consider here the production of meson pairs, involving tensor and pseudotensor mesons, in photon-photon collisions.Comment: LaTeX, 5 pages, 1 embedded ps figure, uses macros sprocl.sty, epsfig.sty. Talk delivered by F. Murgia at the PHOTON'97 Conference, Egmond aan Zee, The Netherlands, May 10-15, 1997. To be published in the proceedings by World Scientifi

    Evaluating Effects of Tax Preferences on Health Care Spending and Federal Revenues

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    In this paper, we calculate the consequences for health spending and federal revenues of an above-the-line deduction for out-of-pocket health spending. We show how the response of spending to this expansion in the tax preference can be specified as a function of a small number of behavioral parameters that have been estimated in the existing literature. We compare our estimates to those from other researchers. And, we use our analysis to derive some implications for tax policy toward HSAs.

    Fabric variability within layered Fe-oxide deposits in Mid-late Miocene sedimentary formations, NW Borneo: impact on facies architectural interpretations

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    Iron (Fe) can accumulate in various forms in sedimentary environments that experience alternating moisture conditions, hydration and dehydration processes and redox processes. It has been pointed out that there is a major gap in the understanding of the composition of mixed solid-phase minerals, their size, morphology and arrangement in the matrix and possible interactions with pore solutions and the environment of deposition. Variations in the fabric within concretions in some Mid-Late Miocene beds in NW Borneo suggest that there were more changes in the energy levels and processes involved than what has been perceived from routine fabric analyses of the sedimentary rocks. The sedimentary rocks are essentially carbonaceous claystones containing varying amounts of highly restricted marginal-marine fauna. The fauna probably accumulated in brackish waters, and comprise in-situ buried turritellid snails, fish teeth and bone tissue, fragments of crabs, very few forams and possibly ostracod shells. Evidence exists to support the concept of reworked cobble or pebble-sized fossiliferous mudstones picking up contemporaneous shell fragments in these restricted conditions. Iron oxide content is seen as (i) micrite-size primary components forming part of a muddy matrix and (ii) diagenetic coatings. Coatings occur in a non-rhythmical pattern after the formation of mudstones, and the reworking of the material and subsequent coatings by iron. Iron coated pebbles/cobbles may experience re-cementing into large sheets giving the appearance of red beds. These occur under some very special redox conditions. These iron-concretion rich horizons appear then to represent extreme (climatic, etc) facies developments that were restricted to coastal areas during Mid-Late Miocene. Present-day iron deposition processes might be a key to understanding past processes. This study forms the basis for an enhanced understanding on facies architectural interpretations

    Signatures of Dark Matter Scattering Inelastically Off Nuclei

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    Direct dark matter detection focuses on elastic scattering of dark matter particles off nuclei. In this study, we explore inelastic scattering where the nucleus is excited to a low-lying state of 10-100 keV, with subsequent prompt de-excitation. We calculate the inelastic structure factors for the odd-mass xenon isotopes based on state-of-the-art large-scale shell-model calculations with chiral effective field theory WIMP-nucleon currents. For these cases, we find that the inelastic channel is comparable to or can dominate the elastic channel for momentum transfers around 150 MeV. We calculate the inelastic recoil spectra in the standard halo model, compare these to the elastic case, and discuss the expected signatures in a xenon detector, along with implications for existing and future experiments. The combined information from elastic and inelastic scattering will allow to determine the dominant interaction channel within one experiment. In addition, the two channels probe different regions of the dark matter velocity distribution and can provide insight into the dark halo structure. The allowed recoil energy domain and the recoil energy at which the integrated inelastic rates start to dominate the elastic channel depend on the mass of the dark matter particle, thus providing a potential handle to constrain its mass.Comment: 9 pages, 7 figures. Matches resubmitted version to Phys. Rev. D. One figure added; supplemental material (fits to the structure functions) added as an Appendi

    Insulin-Like Growth Factor (IGF)-I and -11 and IGFBinding Proteins-l, -2, and -3 in Children and Adolescents with Diabetes Mellitus: Correlation with Metabolic Control and Height Attainment.

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    The putative effects of diabetes and metabolic control on circulating levels of insulin-like growth factors (IGFs) and their binding proteins (IGFBPs) remain controversial. In the present study, serum levels of IGF-I and IGF-II and IGFBP-1, -2, and -3 were measured in 58 patients (age, 0.8-17 yr) with treated (51 subjects) or untreated (7 subjects) insulin-dependent diabetes mellitus (IDDM) and were compared with the levels in normal subjects. In the untreated patients IGF-I and IGF-II were decreased as compared with the healthy controls. In the treated diabetics IGF-I and IGF-II were reduced; IGFBP-2 (only in prepubertal subjects) and IGFBP-3 were increased. Furthermore, age-adjusted values of IGF-I, IGF-II, and IGFBP-3 were lower in prepubertal than in pubertal patients. Regression analysis revealed a negative correlation between hemoglobin (Hb)A1c and standard deviation scores (SDS) of IGF-I and a positive association between HbA1c and IGFBP-1 SDS or IGFBP-2 SDS. In the treated patients HbA1c was positively related to IGFBP-1 SDS and IGFBP-2 SDS when applying simple regression analysis and to IGFBP-2 SDS when using a multiple regression model. Strong correlations were observed between height SDS and IGF-I SDS, IGF-II SDS, and IGFBP-3 SDS in prepubertal subjects who had had IDDM for at least 2 yr, but not in adolescents. Such correlations have also been found in healthy children and adolescents. In conclusion; 1) IDDM is associated with alterations of the IGF-IGFBP system, which are partially accounted for by differences in metabolic control and pubertal status; 2) the lower plasma concentrations of serum IGF-I may play a role in the pathogenesis of growth impairment of poorly controlled prepubertal, but not pubertal, children and adolescents with IDDM; and 3) in addition, a potential role of the altered IGF-IGFBP system for the development of diabetic late complications is hypothesized
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