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Exponential Dependence (exponential + dependence)
Selected AbstractsAlu-DNA repeat-binding protein p68 is a part of Alu-RNA containing ,-RNPFEBS JOURNAL, Issue 8 2000Dmitry V. Lukyanov An Alu-DNA repeat-binding protein with a molecular mass of 68 kDa (p68) is identified in the somatic human cell nucleoplasm. Gel mobility shift assay (GMSA), South-western blotting and affinity purification on DNA attached to the carrier were used in the identification. GMSA revealed multiple complexes with the exponential dependence of their relative mobility. A narrow binding site of the p68 was revealed using synthetic oligonucleotides. It is located between the A-box and B-box of the RNA polymerase III promoter and is identical to that reported for the Alu-binding protein from human spermatozoids. The same narrow binding site, the similarity of the isolation procedure from germ and somatic cells, and similar binding properties and molecular masses suggest homology of the two proteins. Antibodies raised against Alu-protein complexes led to hypershift of the complexes in GMSA and stained p68 in active fractions in human spermatozoids and in Alu-RNA-containing ,-RNP particles. Immunofluorescence of a HeLa cell monolayer revealed an intranuclear dot pattern with the dots corresponding to euchromatin areas and some dots located at the cell periphery in the cytoplasm. ,-RNP particles bound Alu-DNA in vitro and contained p68 as shown using the immunogold procedure. Alu-DNA binding activity was revealed in cytoplasm as well as in nucleoplasm. The possible nature of the main Alu-DNA binding protein and its involvement in the particle structure are discussed. [source] On the absence of large-order divergences in superstring theoryFORTSCHRITTE DER PHYSIK/PROGRESS OF PHYSICS, Issue 1 2003S. Davis The genus-dependence of multi-loop superstring amplitudes is estimated at large orders in perturbation theory using the super-Schottky group parameterization of supermoduli space. Restriction of the integration region to a subset of supermoduli space and a single fundamental domain of the super-modular group suggests an exponential dependence on the genus. Upper bounds for these estimates are obtained for arbitrary N-point superstring scattering amplitudes and are shown to be consistent with exact results obtained for special type II string amplitudes for orbifold or Calabi-Yau compactifications. The genus-dependence is then obtained by considering the effect of the remaining contribution to the superstring amplitudes after the coefficients of the formally divergent parts of the integrals vanish as a result of a sum over spin structures. The introduction of supersymmetry therefore leads to the elimination of large-order divergences in string perturbation theory, a result which is based only on the supersymmetric generalization of the Polyakov measure and not the gauge group of the string model. [source] Effects of temperature and sediment properties on benthic CO2 production in an oligotrophic boreal lakeFRESHWATER BIOLOGY, Issue 8 2010IRINA BERGSTRÖM Summary 1. Temperature and many other physical and chemical factors affecting CO2 production in lake sediments vary significantly both seasonally and spatially. The effects of temperature and sediment properties on benthic CO2 production were studied in in situ and in vitro experiments in the boreal oligotrophic Lake Pääjärvi, southern Finland. 2. In in situ experiments, temperature of the water overlying the shallow littoral sediment varied seasonally between 0.5 and 15.7 °C, but in deep water (,20 m) the range was only 1.1,6.6 °C. The same exponential model (r2 = 0.70) described the temperature dependence at 1.2, 10 and 20 m depths. At 2.5 and 5 m depths, however, the slopes of the two regression models (r2 = 0.94) were identical but the intercept values were different. Sediment properties (wet, dry, mineral and organic mass) varied seasonally and with depth, but they did not explain a significantly larger proportion of variation in the CO2 output rate than temperature. 3. In in vitro experiments, there was a clear and uniform exponential dependence of CO2 production on temperature, with a 2.7-fold increase per 10 °C temperature rise. The temperature response (slope of regression) was always the same, but the basic value of CO2 production (intercept) varied, indicating that other factors also contributed to the benthic CO2 output rate. 4. The annual CO2 production of the sediment in Lake Pääjärvi averaged 62 g CO2 m,2, the shallow littoral at 0,3 m depth releasing 114 g CO2 m,2 and deep profundal (>15 m) 30 g CO2 m,2. On the whole lake basis, the shallow littoral at 0,3 m depth accounted for 53% and the sediment area in contact with the summer epilimnion (down to a depth c. 10 m) 75% of the estimated total annual CO2 output of the lake sediment, respectively. Of the annual production, 83% was released during the spring and summer. 5. Using the temperature-CO2 production equations and climate change scenarios we estimated that climatic warming might increase littoral benthic CO2 production in summer by nearly 30% from the period 1961,90 to the period 2071,2100. [source] Determination of Scattering and Absorption Coefficients for Plasma-Sprayed Yttria-Stabilized Zirconia Thermal Barrier CoatingsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 5 2008Jeffrey I. Eldridge Prediction of radiative transport through translucent thermal barrier coatings (TBCs) can only be performed if the scattering and absorption coefficients and index of refraction of the TBC are known. To date, very limited information on these coefficients, which depend on both the coating composition and the microstructure, has been available for the very commonly utilized plasma-sprayed 8 wt% yttria-stabilized zirconia (8YSZ) TBCs. In this work, the scattering and absorption coefficients of freestanding plasma-sprayed 8YSZ coatings were determined from room-temperature normal-incidence directional-hemispherical reflectance and transmittance spectra over the wavelength range from 0.8 to 7.5 ,m. Spectra were collected over a wide range of coating thickness from 60 to almost 900 ,m. From the reflectance and transmittance spectra, the scattering and absorption coefficients as a function of wavelength were obtained by fitting the reflectance and transmittance values predicted by a four flux model to the experimentally measured values at all measured 8YSZ thicknesses. While the combined effects of absorption and scattering were shown in general to exhibit a nonexponential dependence of transmittance on specimen thickness, it was shown that for sufficiently high absorption and optical thickness, an exponential dependence becomes a good approximation. In addition, the implications of the wavelength dependence of the plasma-sprayed 8YSZ scattering and absorption coefficients on (1) obtaining accurate surface-temperature pyrometer measurements and on (2) applying mid-infrared reflectance to monitor TBC delamination are discussed. [source] Loss inclusion via dyadic Green's function modifications for microstrip structures with complex media: Interfacial exponential field behavior within conductor ,MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 1 2001Clifford M. Krowne Abstract 2-D field behavior within a metal strip is used to correct the dyadic Green's function for a microstrip structure containing complex-layered media so that the attenuation constant can be determined. In the x -direction, the field is built to display exponential dependence. The strip width is explicitly taken into account, along with the metal thickness and conductivity. New Green's function expressions of the structure are found consistent with a full-wave electromagnetic code employing zero thickness extent conductors for the guiding metal. Implications for numerical implementation are covered. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 30: 54,60, 2001. [source] Optical Properties of Human Melanocytic Nevi In VivoPHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 1 2009George Zonios We present an in vivo study of the optical properties of melanin present in melanocytic nevi of human subjects with Fitzpatrick skin type III (Caucasian descent) using optical spectroscopy. We show that the melanin absorption spectrum exhibits an exponential dependence on wavelength with a decay constant which follows a normal distribution characteristic of a random biological variable. Moreover, we demonstrate lack of correlation among melanin optical properties, melanin concentration and skin light scattering properties, which indicates that the true optical absorption of melanin can be measured free from confounding scattering effects. We also show that the average melanin absorption spectrum in vivo is in very good agreement with a previously reported oxygen photoconsumption action spectrum of melanin. Finally, we provide an overview of the emerging picture of the melanin absorption properties in vivo among various skin types and also among various skin lesions such as melanocytic nevi and melanoma. [source] Analysis of minority carrier lifetime for InAlAs/InGaAs high electron mobility transistors by using 1.55-,m femto-second pulse laserPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 9 2008Hirohisa Taguchi Abstract The minority carrier lifetime (,) of High electron mobility transistors (HEMTs) made using the InAlAs/InGaAs material system lattice-matched to the InP substrate had been obtained from optical response measurements with a 1.55-,m femto-second pulse laser where the laser was illuminated onto the backside of a wafer. The drain current of HEMTs associated with the optical pulse was detected using a digitizing oscilloscope, and , was estimated from the exponential dependence of drain current on time. In our current investigation, we found that , is dominated by the following modes: (1) the amount of time required for holes to transit across the channel toward the source, and (2) the amount of time required for the holes accumulated in the source region to recombine with two-dimensional electron gas (2DEG) through the Auger mechanism. Because the sheet concentration (ps) of holes accumulated in source region is low at a low source-to-drain voltage (VDS), Auger recombination is not predominant, and , was only dominated by the hole transit time. At a high VDS, ps became high enough for Auger recombination to occur and dominate ,. Furthermore, we investigated the optical power dependence of , where the optical power was supplied in a continuous wave (CW) to generate photo-excited holes in a steady state. The value of , decreased monotonically as VDS increased and saturated in as little as 6x10,10 s when the optical power was increased. The theoretical investigation was made to understand this saturation phenomenon. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] | |||||||||||||