5,127 research outputs found
Electromagnetic KY production from the proton in a Regge-plus-resonance approach
A Regge-plus-resonance (RPR) description of the p(\gamma,K)Y and p(e,e'K)Y
processes (Y = \Lambda, \Sigma^{0,+}) is presented. The proposed reaction
amplitude consists of Regge-trajectory exchanges in the t channel, supplemented
with a limited selection of s-channel resonance diagrams. The RPR framework
contains a considerably smaller number of free parameters than a typical
effective-Lagrangian model. Nevertheless, it provides an acceptable overall
description of the photo- and electroproduction observables over an extensive
photon energy range. It is shown that the electroproduction response functions
and polarization observables are particularly useful for fine-tuning both the
background and resonance parameters.Comment: 4 pages, 3 figures, Proceedings for IX International Conference on
Hypernuclear and Strange Particle Physics (HYP2006), October 10-14 2006,
Main
The Own-Price of Money and a New Channel of Monetary Transmission
Traditionally, the effects of monetary policy actions on output are thought to be transmitted via monetary or credit channels. Real business cycle theory, by contrast, highlights the role of real price changes as a source of revisions in spending and production decisions. Motivated by the desire to focus on the effects of price changes in the monetary transmission mechanism, this paper incorporates a direct measure of the real own-price of money into an estimated vector autoregression and a calibrated real business cycle model. Consistent with this new view of the monetary transmission mechanism, both approaches reveal that movements in the own-price of money are strongly related to movements in output.
Cathodoluminescence of nanocrystalline Y2O3:Eu3+ with various Eu3+ concentrations
© The Author(s) 2014. Published by ECS. This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 License (CC BY, http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse of the work in any medium, provided the original work is properly cited.This article has been made available through the Brunel Open Access Publishing Fund.Herein a study on the preparation and cathodoluminescence of monosized spherical nanoparticles of Y2O3:Eu3+ having a Eu3+ concentration that varies between 0.01 and 10% is described. The luminous efficiency and decay time have been determined at low a current density, whereas cathodoluminescence-microscopy has been carried out at high current density, the latter led to substantial saturation of certain spectral transitions. A novel theory is presented to evaluate the critical distance for energy transfer from Eu3+ ions in S6 to Eu3+ ions in C2 sites. It was found that Y2O3:Eu3+ with 1–2% Eu3+ has the highest luminous efficiency of 16lm/w at 15keV electron energy. Decay times of the emission from 5D0 (C2) and 5D1 (C2) and 5D0 (S6) levels were determined. The difference in decay time from the 5D0 (C2) and 5D1 (C2) levels largely explained the observed phenomena in the cathodoluminescence-micrographs recorded with our field emission scanning electron microscope
Cathodoluminescence of Double Layers of Phosphor Particles
This article has been made available through the Brunel Open Access Publishing Fund.We present radiance measurements of particle layers of ZnO:Zn, Y2O3:Eu and Y2O2S:Eu bombarded with electrons at anode voltages between 1 and 15 kV. The layers described in this work refer to single component layers, double layers and two component mixtures. The phosphor layers are deposited on ITO-coated glass slides by settling; the efficiency of the cathodoluminescence is determined by summing the radiances and luminances in the reflected and transmitted modes respectively. The efficiency of a double layer of Y2O3:Eu on top of ZnO:Zn at high electron energy is significantly larger than the efficiency of a corresponding layer in which the two components are mixed. This result is interpreted in terms of the penetration-model, which predicts a larger efficiency for a high-voltage phosphor on top of a low-voltage phosphor. When a layer of the low-voltage phosphor ZnO:Zn is on top of the high-voltage phosphor Y2O3:Eu, we also observe a higher efficiency than that of the corresponding layer with both components mixed. In this case the efficiency increases due to suppression of charging in the Y2O3:Eu layer. Double layers of ZnO:Zn and Y2O2S:Eu did not show enhanced efficiency, because the size of the Y2O2S:Eu particles was too large to evoke the penetration effect.
© The Author(s) 2014. Published by ECS
Oxygen Isotope Tracing of the Solar System.
第2回極域科学シンポジウム/第34回南極隕石シンポジウム 11月18日(金) 国立国語研究所 2階講
The diabetic kidney: a study of diabetic microangiopathy by light and electron microscopy examination of percutaneous renal biopsies
Although there is an extensive literature concerning diabetic
renal involvement, disagreement regarding the diffuse and nodular
glomerular lesions, and uncertainty about their relationship to
pyelonephritis and arteriolosclerosis, have obscured the pathogenesis
of renal disease in diabetes. The general belief,
however, that diabetics are more prone than non -diabetics to
atheroma and other less specific changes in larger blood vessels
in no way detracts from the concept that it is involvement of
small blood vessels, and of capillaries in particular, which
characterises the diabetic lesion.To investigate this problem a light and electron microscopy
examination has been made of renal tissue obtained by percutaaeous
biopsy from selected groups of patients representing different
stages or clinical categories of diabetes and from healthy nondiabetics.
Since reliable quantitative methods must be applied
when electron microscopy is used to demonstrate cellular ultra -
structure, and because the value of data based upon small biopsy
samples is limited unless it can be shown that the tissue obtained
is representative of that individual's glomerular population,
statistical methods appropriate to small samples and free of
assumptions concerning distribution have been used. Thus such
non -parametric methods as the Mann- Whitney 'U' test or the
Kolmogorov-Smirnov analysis of cumulative frequency distribution
have been applied to both the measurement of glomerular capillary
basement membrane thickness and to a technique of assessing on
a quantitative basis, within the glomerular mesangium, the ratio
of basement membrane substance to cellular cytoplasm which has
been designated the Mesangial Index.Using these methods the mean glomerular capillary basement
membrane thickness in nine non -diabetic subjects was 2,200 Å
(Angstrom Units) and although the findings in four newly diagnosed
juvenile diabetics were not significantly different from normal
either in terms of basement membrane thickness or mesangial index,
significant basement membrane thickening was found in seven of ten
patients having diabetes secondary to haemochromatosis, chronic
pancreatitis or pancreatic carcinoma. One of ten age-and duration-matched
long-standing diabetics had no evidence of glomerular
pathology after 23 years of insulin dependence. All other nine
patients had unequivocal basement membrane thickening, however
those without diabetic retinopathy had significantly lower mesnngial
indices than patients having proliferative retinopathy. Thus in
the latter patients there was attenuation of mesangial and endothelial cells with massive basement membrane accumulation. This
aspect was studied further in six diabetics having advancing
proliferative retinopathy by obtaining renal biopsy tissue before
and one to two years after pituitary surgery. Successful
pituitary ablation was followed by significant reduction in the
thickness of the glomerular capillary basement membrane, restoration
of atrophic endothelial and mesanginl cells to their normal
appearance, persistence of morphological features suggesting over-activity
of the epithelial cells and no improvement in the
arteriolar lesion.Other light and electron microscopic features of the diabetic
kidney have been reviewed and the above findings considered in
relation to various clinical factors of significance in the
diagnosis and assessment of diabetic renal disease. Current
aspects of genetic, metabolic, immunological, endocrine and other
factors of possible importance in the pathogenesis of diabetic
small blood vessel disease have been considered in relation to
the findings in this study.It is concluded that although the nodular glomerular lesion
of Kimmelstiel and Wilson remains for the light microscopist the
hallmark of diabetes in the kidney, usually it is found only in
association with the more common diffuse glomerular changes, and
with afferent and efferent arteriolosclerosis. Accompanying
changes in the túbules and interstitial tissue which often in the
past have been interpreted as chronic healed.pyelonephritis probably
represent the end result of diabetic vascular lesions.It is suggested that the excessive basement membrane material
found in the glomerular capillaries probably represents varying
degress of its epithelial production or impaired mesangial turnover.
The absence of glomerular lesions in newly diagnosed juvenile
diabetics and the demonstration of basement membrane lesions in
secondary diabetes suggests that the diabetic lesion is independent
of the genetically determined diathesis to idiopathic diabetes
but is due to some metabolic derangement aommon to both primary and
secondary diabetes. The possibility that some components of
diabetic microangiopathy can occur only in and be due to some
as yet undefined aspect of the idiopathic disorder is, however,
not excluded by these observations. Thus it is probable that
diabetic nephropathy results from several separate though inter-
related lesions each of which may be variously influenced by
the metabolic disturbance, the inherited diabetic diathesis or
pituitary activity.Although the idea of a specific diabetic microangiopathy
is widely accepted, it is concluded that this simple concept
probably conceals the complexity of the factors concerned in the
pathogenesis of the various arteriolar and capillary lesions
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Cathodoluminescence studies of phosphors in a scanning electron microscope
Cathodoluminescence studies are reported of phosphors in a field emission scanning electron microscope (FESEM). A number of phosphor materials have been studied and exhibited a pronounced comet-like structure at high scan rates, because the particle continued to emit light after the beam had moved onto subsequent pixels. Image analysis has been used to study the loss of brightness along the tail and hence to determine the decay time of the materials. This technique provides a simple and convenient way to study the decay times of individual particles
Statistical Properties of Interacting Bose Gases in Quasi-2D Harmonic Traps
The analytical probability distribution of the quasi-2D (and purely 2D) ideal
and interacting Bose gas are investigated by using a canonical ensemble
approach. Using the analytical probability distribution of the condensate, the
statistical properties such as the mean occupation number and particle number
fluctuations of the condensate are calculated. Researches show that there is a
continuous crossover of the statistical properties from a quasi-2D to a purely
2D ideal or interacting gases. Different from the case of a 3D Bose gas, the
interaction between atoms changes in a deep way the nature of the particle
number fluctuations.Comment: RevTex, 10pages, 4 figures, E-mail: [email protected]
Versican splice variant messenger RNA expression in normal human Achilles tendon and tendinopathies
Versican is the principal large proteoglycan expressed in mid-tendon, but its role in tendon pathology is unknown. Our objective was to define the expression of versican isoform splice variant messenger ribonucleic acid (mRNA) in normal Achilles tendons, in chronic painful tendinopathy and in ruptured tendons. Total RNA isolated from frozen tendon samples (normal n = 14; chronic painful tendinopathy n = 10; ruptured n = 8) was assayed by relative quantitative reverse transcriptase polymerase chain reaction (RT-PCR) for total versican, versican variants V0, V1, V2, V3 and type I collagen a1 mRNA, normalized to glyceraldehyde-3-phosphate dehydrogenase (GAPDH). Differences between sample groups were tested by Wilcoxon statistics. Painful and ruptured tendons showed a significant decrease (median 2-fold) in the expression of versican mRNA, in contrast to an increased expression (median 8-fold) of type I collagen a1 mRNA in painful tendons. Versican splice variants V0 and V1 mRNA were readily detected in normal samples, V3 levels were substantially lower, and V2 levels were more variable. Each of V1, V2 and V3 mRNA showed significant decreases in expression in painful and ruptured tendons, but V0 was not significantly changed. Changes in versican expression relative to that of collagen, and alterations in the balance of versican splice variants, may contribute to changes in matrix structure and function in tendinopathies
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