1,856 research outputs found

    Nominal and real disturbances and money demand in the Chinese hyperinflation

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    This paper reexamines the dynamics of hyperinflation by allowing variability in the relative price of capital goods in units of consumption goods that reflects interactions between the real and monetary sectors. The theory generates empirically testable implications that suggest expanding the standard Caganian money demand function to include both anticipated inflation and relative price effects in a nonlinear fashion. Employing data from the post-World War II Chinese hyperinflationary episode, the empirical findings suggest that conventional econometric investigations of money demand during hyperinflation overlook important nonlinear interactions between real and monetary activities and, hence, underestimate the welfare costs of hyperinflation.Inflation (Finance) ; China ; Economic conditions - China

    Loop quantum gravity effects on inflation and the CMB

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    In loop quantum cosmology, the universe avoids a big bang singularity and undergoes an early and short super-inflation phase. During super-inflation, non-perturbative quantum corrections to the dynamics drive an inflaton field up its potential hill, thus setting the initial conditions for standard inflation. We show that this effect can raise the inflaton high enough to achieve sufficient e-foldings in the standard inflation era. We analyze the cosmological perturbations generated when slow-roll is violated after super-inflation, and show that loop quantum effects can in principle leave an indirect signature on the largest scales in the CMB, with some loss of power and running of the spectral index.Comment: revtex4, 5 pages, 3 figures, significant improvements in explanation of quantization and perturbation issues; version to appear Classical and Quantum Gravit

    Into building fading at L- and S-band for satellite PCS

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    Selected results from L- and S-Band slant-path fade measurements into six different buildings employing a tower-mounted transmitter and dual-frequency receiver are presented. The objective of the measurements was to provide information for personal communications satellite design on the correlation of fading inside buildings between frequencies near 1620 and 2500 MHz. Fades were measured along horizontal directions with 5 cm spacing. Fade differences between L- and S-Band exhibited a normal distribution with means usually near 0 dB and standard deviations from 7.2 to 8.2 dB. After spatial averaging over a few wavelengths, the correlation between L- and S-Band was significantly improved. Simultaneous swept measurements over 160 MHz spans showed that the standard deviation of the power levels as function of frequency increased linearly with average fade depth from a minimum of about 1.3 dB and increased by .2 dB per 1 dB of fade. Fade slopes were also a function of fade level, with LMSS-Band averages in the range of 1 to 2 dB/MHz for 10 dB fades and increasing to about 3 to 4 dB/MHz at a 30 dB fade

    Single-fiber reflectance spectroscopy of isotropic-scattering medium: An analytic perspective to the ratio-of-remission in steady-state measurements

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    Recent focused Monte Carlo and experimental studies on steady-state single-fiber reflectance spectroscopy (SfRS) from a biologically relevant scattering medium have revealed that, as the dimensionless reduced scattering of the medium increases, the SfRS intensity increases monotonically until reaching a plateau. The SfRS signal is semi-empirically decomposed to the product of three contributing factors, including a ratio-of-remission (RoR) term that refers to the ratio of photons remitting from the medium and crossing the fiber-medium interface over the total number of photons launched into the medium. The RoR is expressed with respect to the dimensionless reduced scattering parameter μ's dfib, where μ's is the reduced scattering coefficient of the medium and dfib is the diameter of the probing fiber. We develop in this work, under the assumption of an isotropic-scattering medium, a method of analytical treatment that will indicate the pattern of RoR as a function of the dimensionless reduced scattering of the medium. The RoR is derived in four cases, corresponding to in-medium (applied to interstitial probing of biological tissue) or surface-based (applied to contact-probing of biological tissue) SfRS measurements using straight-polished or angle-polished fiber. The analytically arrived surface-probing RoR corresponding to single-fiber probing using a 15° angle-polished fiber over the range of μ's dfib = (10-2 103) agrees with previously reported similarly configured experimental measurement from a scattering medium that has a Henyey-Greenstein scattering phase function with an anisotropy factor of 0.8. In cases of a medium scattering lightanisotropically, we propose how the treatment may be furthered to account for the scattering anisotropy using the result of a study of light scattering close to the point-of-entry by Vitkin et al.Electrical & Computer Engineerin

    Preferential loss of a polymorphic RIZ allele in human hepatocellular carcinoma

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    The RIZ (PRDM2) locus commonly undergoes loss of heterozygosity (LOH) and maps within the minimal deleted region on 1p36 in hepatocellular carcinoma (HCC). Although peptide-altering mutations of RIZ are rare in HCC, the RIZ1 product is commonly lost in HCC and has tumour suppressive activities. Here, we analysed RIZ gene mutations and LOH in HCC, breast cancer, familial melanoma, colon cancer, and stomach cancer. We found 7 polymorphisms but no mutations. By analysing the Pro704-deletion polymorphism, we detected LOH of RIZ in 31 of 79 (39%) informative HCC cases, 11 of 47 (23%) colon cancer cases, 8 of 43 (19%) breast cancer cases, 8 of 66 (12%) stomach cancer cases. Importantly, loss of the Pro704+allele was found in 74% of the 31 LOH positive HCC cases (P< 0.01), indicating a preferential loss and hence a stronger tumour suppressor role for this allele compared to the P704−allele. In addition, the Pro704+allele was found to be more common in Asians (0.61) than Caucasians (0.42) (P = 0.0000), suggesting an interesting link between gene polymorphisms and potential differences in tumour incidence between racial groups. © 2001 Cancer Research Campaign http://www.bjcancer.co

    European land CO2 sink influenced by NAO and East-Atlantic Pattern coupling

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    Large-scale climate patterns control variability in the global carbon sink. In Europe, the North-Atlantic Oscillation (NAO) influences vegetation activity, however the East-Atlantic (EA) pattern is known to modulate NAO strength and location. Using observation-driven and modelled data sets, we show that multi-annual variability patterns of European Net Biome Productivity (NBP) are linked to anomalies in heat and water transport controlled by the NAO-EA interplay. Enhanced NBP occurs when NAO and EA are both in negative phase, associated with cool summers with wet soils which enhance photosynthesis. During anti-phase periods, NBP is reduced through distinct impacts of climate anomalies in photosynthesis and respiration. The predominance of anti-phase years in the early 2000s may explain the European-wide reduction of carbon uptake during this period, reported in previous studies. Results show that improving the capability of simulating atmospheric circulation patterns may better constrain regional carbon sink variability in coupled carbon-climate models

    Low Temperature Precursor Route for Highly Efficient Spherically Shaped LED-Phosphors M2Si5N8:Eu2+ (M = Eu, Sr, Ba)

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    The highly efficient nitridosilicate phosphors M2Si5N8 (M = Sr, Ba, Eu) for phosphor-converted pc-LEDs were synthesized at low temperatures using a novel precursor route involving metal amides M(NH2)2. These precursors have been synthesized by dissolution of the respective metals in supercritical ammonia at 150°C and 300 bar. The thermal behavior and decomposition process of the amides were investigated with temperature programmed powder X-ray diffractometry and thermoanalytical measurements (DTA/TG). These investigations rendered the amides as suitable intermediates for reaction with silicon diimide (Si(NH)2). Thus, the desired nitridosilicate phosphors were obtained at relatively low temperatures around 1150−1400°C which is approximately 300°C lower compared to common synthetic approaches starting from metals or oxides. The influence of the thermal treatment on the phosphor morphology has been studied extensively. The accessibility of spherical phosphor particles represents another striking feature of this route since it improves light extraction from the crystallites due to decreasing light guiding and decreasing re-absorption inside the phosphor particle. The synthesized luminescent materials M2Si5N8:Eu2+ (M = Sr, Ba) exhibit quantum efficiencies and emission band widths (FWHM 70−90 nm) comparable to standard phosphor powders. Employment of Eu(NH2)2 as dopant reagent for synthesis of Ba2Si5N8:Eu2+ proved favorable for the formation of spherical crystallites compared to doping with Eu metal, halides, or oxide

    Mirage Cosmology of U(1) Gauge Field on Unstable D3 Brane Universe

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    An unstable D3D3-brane universe governed by the DBI action of the tachyon field minimally coupled to a U(1) gauge boson is examined. The cosmological evolution of this coupled system, is further analyzed, in terms of the expansion rate of the inflating brane, which is highly affected by the presence of the tachyonic and gauge field charges. We show, that the minimal coupling makes the effective brane density less divergent. However, for some sectors of the theory the tachyon is not able to regulate it in an efficient fashion. Also, a detailed analysis of the dependance of the effective brane density on the scale factor of the universe is performed, which leads to various cosmological models.Comment: ReVTeX format 20 pages; v2 1 figure added, one additional paragraph with extra comments added, enlarged list of references, version to appear in JHE

    Dynamics of Tachyon and Phantom Field beyond the Inverse Square Potentials

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    We investigate the cosmological evolution of the tachyon and phantom-tachyon scalar field by considering the potential parameter Γ\Gamma(=VV"V′2=\frac{V V"}{V'^2}) as a function of another potential parameter λ\lambda(=V′κV3/2=\frac{V'}{\kappa V^{3/2}}), which correspondingly extends the analysis of the evolution of our universe from two-dimensional autonomous dynamical system to the three-dimension. It allows us to investigate the more general situation where the potential is not restricted to inverse square potential and .One result is that, apart from the inverse square potential, there are a large number of potentials which can give the scaling and dominant solution when the function Γ(λ)\Gamma(\lambda) equals 3/23/2 for one or some values of λ∗\lambda_{*} as well as the parameter λ∗\lambda_{*} satisfies condition Eq.(18) or Eq.(19). We also find that for a class of different potentials the dynamics evolution of the universe are actually the same and therefore undistinguishable.Comment: 8 pages, no figure, accepted by The European Physical Journal C(2010), online first, http://www.springerlink.com/content/323417h708gun5g8/?p=dd373adf23b84743b523a3fa249d51c7&pi=
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