541 research outputs found

    On the rescaled Riemannian metric of Cheeger Gromoll type on the cotangent bundle

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    Let (M,g)(M,g) be an n-dimensional Riemannian manifold and TMT^{*}M be its cotangent bundle equipped with a Riemannian metric of Cheeger Gromoll type which rescale the horizontal part by a nonzero differentiable function. The main purpose of the present paper is to discuss curvature properties of TMT^{*}M and construct almost paracomplex Norden structures on TMT^{*}M. We investigate conditions for these structures to be para-K\"ahler (paraholomorphic) and quasi-K\"ahler. Also, some properties of almost paracomplex Norden structures in context of almost product Riemannian manifolds are presented

    Readout of GEM Detectors Using the Medipix2 CMOS Pixel Chip

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    We have operated a Medipix2 CMOS readout chip, with amplifying, shaping and charge discriminating front-end electronics integrated on the pixel-level, as a highly segmented direct charge collecting anode in a three-stage gas electron multiplier (Triple-GEM) to detect the ionization from 55^{55}Fe X-rays and electrons from 106^{106}Ru. The device allows to perform moderate energy spectroscopy measurements (20 % FWHM at 5.9 keV XX-rays) using only digital readout and two discriminator thresholds. Being a truly 2D-detector, it allows to observe individual clusters of minimum ionizing charged particles in Ar/CO2Ar/CO_2 (70:30) and He/CO2He/CO_2 (70:30) mixtures and to achieve excellent spatial resolution for position reconstruction of primary clusters down to 50μm\sim 50 \mu m, based on the binary centroid determination method.Comment: 18 pages, 14 pictures. submitted to Nuclear Instruments and Methods in Physics Research

    Development of Thick-foil and Fine-pitch GEMs with a Laser Etching Technique

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    We have produced thick-foil and fine-pitch gas electron multipliers (GEMs) using a laser etching technique. To improve production yield we have employed a new material, Liquid Crystal Polymer, instead of polyimide as an insulator layer. The effective gain of the thick-foil GEM with a hole pitch of 140 um, a hole diameter of 70 um, and a thickness of 100 um reached a value of 10^4 at an applied voltage of 720 V. The measured effective gain of the thick-foil and fine-pitch GEM (80 um pitch, 40 um diameter, and 100 um thick) was similar to that of the thick-foil GEM. The gain stability was measured for the thick-foil and fine-pitch GEM, showing no significant increase or decrease as a function of elapsed time from applying the high voltage. The gain stability over 3 h of operation was about 0.5%. Gain mapping across the GEM showed a good uniformity with a standard deviation of about 4%. The distribution of hole diameters across the GEM was homogeneous with a standard deviation of about 3%. There was no clear correlation between the gain and hole diameter maps.Comment: 21 pages, 9 figure

    THE COST STRUCTURE OF MICROFINANCE INSTITUTIONS IN EASTERN EUROPE AND CENTRAL ASIA

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    Microfinance institutions are important, particularly in developing countries, because they expand the frontier of financial intermediation by providing loans to those traditionally excluded from formal financial markets. This paper presents the first systematic statistical examination of the performance of MFIs operating in Eastern Europe and Central Asia. A cost function is estimated for MFIs in the region from 1999-2004. First, the presence of subsidies is found to be associated with higher MFI costs. When output is measured as the number of loans made, we find that MFIs become more efficient over time and that MFIs involved in the provision of group loans and loans to women have lower costs. However, when output is measured as volume of loans rather than their number, this last finding is reversed. This may be due to the fact that such loans are smaller in size; thus for a given volume more loans must be made.http://deepblue.lib.umich.edu/bitstream/2027.42/40195/3/wp809.pd

    Light multi-GEM detector for high-resolution tracking systems

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    Controlled etching of copper electrodes in Gas Electron Multiplier foils allows a reduction of the material budget by more than a factor of two for a triple-GEM detector. Detectors making use of thinned foils provide performances similar to those obtained with standard devices: a gain above 10^4 for a double-GEM, with energy resolution of 27 % fwhm for 5.9 keV X-rays.Comment: Submitted to Nucl.Instr.& Meth.

    Construction, test and commissioning of the triple-GEM tracking detector for COMPASS

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    The Small Area Tracking system of the COMPASS experiment at CERN includes a set of 20 large area, fast position-sensitive Gas Electron Multiplier (GEM) detectors, designed to reliably operate in the harsh radiation environment of the experiment. We describe in detail the design, choice of materials, assembly procedures and quality controls used to manufacture the devices. The test procedure in the laboratory, the performance in test beams and in the initial commissioning phase in the experiment are presented and discussed

    The Threat of Capital Drain: A Rationale for Public Banks?

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    This paper yields a rationale for why subsidized public banks may be desirable from a regional perspective in a financially integrated economy. We present a model with credit rationing and heterogeneous regions in which public banks prevent a capital drain from poorer to richer regions by subsidizing local depositors, for example, through a public guarantee. Under some conditions, cooperative banks can perform the same function without any subsidization; however, they may be crowded out by public banks. We also discuss the impact of the political structure on the emergence of public banks in a political-economy setting and the role of interregional mobility
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