Search results for "difference"
showing 10 items of 1534 documents
�ber die Minimall�sung der Poincar�-Perronschen Differenzengleichung
1991
This paper deals with a special class of solutions of the higher order linear difference equation. It is shown that the minimal solution of Poincare-Perron type equations can be expressed in terms of generalized continued fractions.
Relative differential forms and complex polynomials
2000
Younger bank voles are more vulnerable to avian predation
2008
The importance of predation on prey populations is mainly determined by the number of eaten prey. However, the total impact of predation might also be determined by the selection of certain prey individuals, e.g., different sexes or age categories. Here we tested selective predation by an avian predator, the pygmy owl ( Glaucidium passerinum (L., 1758)), on bank voles ( Myodes ( Clethrionomys ) glareolus (Schreber, 1780)). We compared the sex, age, and mass of hoarded prey with the animals snap-trapped from the field. There were no differences in the sex ratio between hoarded bank voles and those available in the field. However, hoarded voles were significantly younger than ones in the fie…
Hybrid-Functional Calculations on the Incorporation of Na and K Impurities into the CuInSe 2 and CuIn 5 Se 8 Solar-Cell Materials
2015
International audience; We have studied the energetics, atomic, and electronic structure of Na and K point defects, as well as the (Na-Na), (K-K), and (Na-K) dumbbells in CuInSe2 and CuIn5Se8 solar cell materials by hybrid functional calculations. We found that although Na and K behaves somewhat similar; there is a qualitative difference between the inclusion of Na and K impurities. Namely, Na will be mostly incorporated into CuInSe2 and CuIn5Se8 either as an interstitial defect coordinated by cations, or two Na impurities will form (Na-Na) dumbbells in the Cu sublattice. In contrast to Na, K impurities are less likely to form interstitial defects. Instead, it is more preferable to accommod…
The Polarised Valence Quark Distribution from semi-inclusive DIS
2007
The semi-inclusive difference asymmetry A^{h^{+}-h^{-}} for hadrons of opposite charge has been measured by the COMPASS experiment at CERN. The data were collected in the years 2002-2004 using a 160 GeV polarised muon beam scattered off a large polarised ^6LiD target and cover the range 0.006 < x < 0.7 and 1 < Q^2 < 100 (GeV/c)^2. In leading order QCD (LO) the asymmetry A_d^{h^{+}-h^{-}} measures the valence quark polarisation and provides an evaluation of the first moment of Delta u_v + Delta d_v which is found to be equal to 0.40 +- 0.07 (stat.) +- 0.05 (syst.) over the measured range of x at Q^2 = 10 (GeV/c)^2. When combined with the first moment of g_1^d previously measured …
FDTD characterization of evanescent modes-multimode analysis of waveguide discontinuities
2000
In this paper, a finite-difference time-domain numerical dispersion relation for evanescent waves is derived, and its impact on the modeling accuracy is studied. The numerical evanescent constant is found to differ from the analytical one. As a result, a correction must be used to compute discontinuity parameters. This influences the reference plane chosen for the analysis of propagating modes. Moreover, on calculating multimode transmission and reflection coefficients, the dispersion for evanescent higher order modes is determinant. The dispersive relation is derived, discussed, and used to correct the evanescent constants for the multimode analysis of a waveguide discontinuity.
Valutazione comparativa delle sequenze fast Spin-echo e Spin-echo T2-dipendenti nella dimostrazione delle lesioni demielinizzanti encefaliche in cors…
1997
We compared T2-weighted fast spin-echo (FSE) magnetic resonance (MR) imaging and conventional spin-echo (CSE) T2-weighted imaging in the detection of brain lesions of multiple sclerosis (MS). 20 patients with clinically definite MS underwent brain imaging with both FSE and CSE T2-weighted imaging. There was no significant difference in total number of lesions detected on FSE vs CSE (1354 vs 1378). Slightly more periventricular and subcortical lesions were detected using CSE than FSE, whereas more posterior cranial fossa lesions were detected by FSE. There was no statistically significant difference in the signal intensity (SI) ratio of MS lesions to that of surrounding normal white matter …
Evaluation of halitosis and sialometry in patients submitted to head and neck radiotherapy
2009
Objectives: The aim of this study was to investigate the parameters of halitosis and sialometry in patients who had undergone head and neck radiotherapy, correlating oral concentration of volatile sulfur compounds (VSC) with the presence of tongue coating, salivary flow rate and BANA test. Material and Methods: 35 patients allocated in two groups were examined: group I (control) - patients with systemic and oral health; group II - patients submitted to head and neck radiotherapy. All volunteers were submitted to halitosis measurements through a sulphide monitor, evaluation of tongue coating weight, non-stimulated sialometry and BANA test. Results: The results were analyzed through analysis …
Timing and patterns of the ENSO signal in Africa over the last 30 years: insights from normalized difference vegetation index data.
2014
Abstract A more complete picture of the timing and patterns of the ENSO signal during the seasonal cycle for the whole of Africa over the three last decades is provided using the normalized difference vegetation index (NDVI). Indeed, NDVI has a higher spatial resolution and is more frequently updated than in situ climate databases, and highlights the impact of ENSO on vegetation dynamics as a combined result of ENSO on rainfall, solar radiation, and temperature. The month-by-month NDVI–Niño-3.4 correlation patterns evolve as follows. From July to September, negative correlations are observed over the Sahel, the Gulf of Guinea coast, and regions from the northern Democratic Republic of Congo…
Spatial Search by Quantum Walk is Optimal for Almost all Graphs.
2015
The problem of finding a marked node in a graph can be solved by the spatial search algorithm based on continuous-time quantum walks (CTQW). However, this algorithm is known to run in optimal time only for a handful of graphs. In this work, we prove that for Erd\"os-Renyi random graphs, i.e.\ graphs of $n$ vertices where each edge exists with probability $p$, search by CTQW is \textit{almost surely} optimal as long as $p\geq \log^{3/2}(n)/n$. Consequently, we show that quantum spatial search is in fact optimal for \emph{almost all} graphs, meaning that the fraction of graphs of $n$ vertices for which this optimality holds tends to one in the asymptotic limit. We obtain this result by provin…