2,298 research outputs found
Summary of along-track data from the earth radiation budget satellite for several representative ocean regions
For several days in January and August 1985, the Earth Radiation Budget Satellite, a component of the Earth Radiation Budget Experiment (ERBE), was operated in an along-track scanning mode. A survey of radiance measurements taken in this mode is given for five ocean regions: the north and south Atlantic, the Arabian Sea, the western Pacific north of the Equator, and part of the Intertropical Convergence Zone. Each overflight contains information about the clear scene and three cloud categories: partly cloudy, mostly cloudy, and overcast. The data presented include the variation of longwave and shortwave radiance in each scene classification as a function of viewing zenity angle during each overflight of one of the five target regions. Several features of interest in the development of anisotropic models are evident, including the azimuthal dependence of shortwave radiance that is an essential feature of shortwave bidirectional models. The data also demonstrate that the scene classification algorithm employed by the ERBE results in scene classifications that are a function of viewing geometry
Summary of along-track data from the Earth radiation budget satellite for several major desert regions
For several days in January and August 1985, the Earth Radiation Budget Satellite, a component of the Earth Radiation Budget Experiment (ERBE), was operated in an along-track scanning mode. A survey of radiance measurements is given for four desert areas in Africa, the Arabian Peninsula, Australia, and the Sahel region of Africa. Each overflight provides radiance information for four scene categories: clear, partly cloudy, mostly cloudy, and overcast. The data presented include the variation of radiance in each scene classification as a function of viewing zenith angle during each overflight of the five target areas. Several features of interest in the development of anisotropic models are evident, including day-night differences in longwave limb darkening and the azimuthal dependence of short wave radiance. There is some evidence that surface features may introduce thermal or visible shadowing that is not incorporated in the usual descriptions of the anisotropic behavior of radiance as viewed from space. The data also demonstrate that the ERBE scene classification algorithms give results that, at least for desert surfaces, are a function of viewing geometry
The Kervaire-Laudenbach conjecture and presentations of simple groups
The statement ``no nonabelian simple group can be obtained from a nonsimple
group by adding one generator and one relator"
1) is equivalent to the Kervaire--Laudenbach conjecture;
2) becomes true under the additional assumption that the initial nonsimple
group is either finite or torsion-free.
Key words: Kervaire--Laudenbach conjecture, relative presentations, simple
groups, car motion, cocar comotion.
AMS MSC: 20E32, 20F05, 20F06.Comment: 20 pages, 13 figure
Comparison of clinical signs and outcomes between dogs with presumptive ischemic myelopathy and dogs with acute non compressive nucleus pulposus extrusion
Forecasting Equicorrelation
We study the out-of-sample forecasting performance of several time-series models of equicorrelation, which is the average pairwise correlation between a number of assets. Building on the existing Dynamic Conditional Correlation and Linear Dynamic Equicorrelation models, we propose a model that uses proxies for equicorrelation based on high-frequency intraday data, and the level of equicorrelation implied by options prices. Using state-of-the-art statistical evaluation technology, we find that the use of both realized and implied equicorrelations outperform models that use daily data alone. However, the out-of-sample forecasting benefits of implied equicorrelation disappear when used in conjunction with the realized measures.Equicorrelation, Implied Correlation, Multivariate GARCH, DCC
The structure of one-relator relative presentations and their centres
Suppose that G is a nontrivial torsion-free group and w is a word in the
alphabet G\cup\{x_1^{\pm1},...,x_n^{\pm1}\} such that the word w' obtained from
w by erasing all letters belonging to G is not a proper power in the free group
F(x_1,...,x_n). We show how to reduce the study of the relative presentation
\^G= to the case n=1. It turns out that an
"n-variable" group \^G can be constructed from similar "one-variable" groups
using an explicit construction similar to wreath product. As an illustration,
we prove that, for n>1, the centre of \^G is always trivial. For n=1, the
centre of \^G is also almost always trivial; there are several exceptions, and
all of them are known.Comment: 15 pages. A Russian version of this paper is at
http://mech.math.msu.su/department/algebra/staff/klyachko/papers.htm . V4:
the intoduction is rewritten; Section 1 is extended; a short introduction to
Secton 5 is added; some misprints are corrected and some cosmetic
improvements are mad
Free subgroups of one-relator relative presentations
Suppose that G is a nontrivial torsion-free group and w is a word over the
alphabet G\cup\{x_1^{\pm1},...,x_n^{\pm1}\}. It is proved that for n\ge2 the
group \~G= always contains a nonabelian free subgroup.
For n=1 the question about the existence of nonabelian free subgroups in \~G is
answered completely in the unimodular case (i.e., when the exponent sum of x_1
in w is one). Some generalisations of these results are discussed.Comment: V3: A small correction in the last phrase of the proof of Theorem 1.
4 page
Force-Velocity Relations of a Two-State Crossbridge Model for Molecular Motors
We discuss the force-velocity relations obtained in a two-state crossbridge
model for molecular motors. They can be calculated analytically in two limiting
cases: for a large number and for one pair of motors. The effect of the
strain-dependent detachment rate on the motor characteristics is studied. It
can lead to linear, myosin-like, kinesin-like and anomalous curves. In
particular, we specify the conditions under which oscillatory behavior may be
found.Comment: 5 pages, 4 figures, REVTeX; thoroughly revised version; also
available at http://www.physik.tu-muenchen.de/~frey
X-Ray Microanalysis of Hollow Heart Potatoes
Electron microprobe and X-ray fluorescence techniques were used to study elemental gradients associated with the physiological disorder hollow heart i n potato tubers. Gradients were found along the length and across the width of mature tubers. These were not rela ted to the disorder, however . Tubers with advanced symptoms of the disorder had elemental levels and gradients similar to those in healthy, control tubers. The results suggest that if the disorder is initially caused by an elemental deficiency, as has sometimes been proposed , the deficiency is temporary and no longer exists in mature tubers with advanced hollow heart. Radial gradients were associated rnd inly with two contrasting tissues . the centra 1 pith and the surrounding perimedullary zone. Tissue differences are critical in microprobe studies involving small samples Microprobe studies of developing tubers containing incipient stages of hollow heart. employing strip samples restricted to the central pith where the disorder originates and taken so as to traverse the small lesions, showed a dramatic increase in Mg in lesion areas. It is suggested that a nutrient imbalance may trigger the onset of the cell necrosis that characterizes the initiation of hollow heart in potato . A localized Mg toxicity or Ca deficiency due to high Mg:Ca ratio is implicated
Evaluation of be-38 percent al alloy final report, 27 jun. 1964 - 28 feb. 1965
Mechanical properties, microstructural features, and general metallurgical quality of beryllium- aluminum allo
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