1,574 research outputs found
Surface circulation in the Great Lakes as observed by LANDSAT-1 August 1972 - December 1973: Southern Lake Michigan
The surface current circulation patterns of southern Lake Michigan were charted for all cardinal and subcardinal wind directions, employing LANDSAT-1 observations of the distribution of natural tracing material borne in the surface waters. These colorants consist chiefly of river discharges composed of suspended sediments, pollutants, and algae; extensive chemical precipitations proved valuable for areas farther from shore. Comparison of the satellite-derived surface current charts with previous theoretical and empirical studies shows good agreement
Receptor localization of steroid hormones and drugs: discoveries through the use of thaw-mount and dry-mount autoradiography
An evaluation of ERTS data for oceanographic uses through Great Lakes studies
The author has identified the following significant results. Prevailing wind direction on Lake Michigan is southwesterly, although during winter northwesterly stresses are common. Along the western shore the current favors a northward direction. ERTS-1 observations indicate that the southward-flowing current along the Michigan shoreline of the thumb is only reversed by southerly resultant wind stress. Along the Canadian shoreline, a northward current was observed north of Kettle Point. ERTS-1 data also reveal that a preferred southward-flowing current is found along the Detroit shoreline of Lake St. Clair. Eastward flow of surface water from the shallow western basin of Lake Erie into the middle basin is most obvious during northwesterly and northerly wind stresses. The reverse wind direction especially east and southeasterly, appear to hold the effluents from the Detroit and Maumee Rivers in the western basin. Across-lake winds from the north and south induce eddy-like circulation in surface waters of Lake Ontario. Counterclockwise alongshore flow persists in the western basin under most wind conditions
Anisotropy of Growth of the Close-Packed Surfaces of Silver
The growth morphology of clean silver exhibits a profound anisotropy: The
growing surface of Ag(111) is typically very rough while that of Ag(100) is
smooth and flat. This serious and important difference is unexpected, not
understood, and hitherto not observed for any other metal. Using density
functional theory calculations of self-diffusion on flat and stepped Ag(100) we
find, for example, that at flat regions a hopping mechanism is favored, while
across step edges diffusion proceeds by an exchange process. The calculated
microscopic parameters explain the experimentally reported growth properties.Comment: RevTeX, 4 pages, 3 figures in uufiles form, to appear in Phys. Rev.
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Thermodynamics of a mixed quantum-classical Heisenberg model in two dimensions
We study the planar antiferromagnetic Heisenberg model on a decorated
hexagonal lattice, involving both classical spins (occupying the vertices) and
quantum spins (occupying the middle of the links). This study is motivated by
the description of a recently synthesized molecular magnetic compound. First,
we trace out the spin 1/2 degrees of freedom to obtain a fully classical model
with an effective ferromagnetic interaction. Then, using high temperature
expansions and Monte Carlo simulations, we analyse its thermal and magnetic
properties. We show that it provides a good quantitative description of the
magnetic susceptibility of the molecular magnet in its paramagnetic phase.Comment: Revtex, 6 pages, 4 included postscript figures, fig.1 upon request to
[email protected] . To appear in J. of Physic C (condensed matter
Anisotropy effects in a mixed quantum-classical Heisenberg model in two dimensions
We analyse a specific two dimensional mixed spin Heisenberg model with
exchange anisotropy, by means of high temperature expansions and Monte Carlo
simulations. The goal is to describe the magnetic properties of the compound
(NBu_{4})_{2}Mn_{2}[Cu(opba)]_{3}\cdot 6DMSO\cdot H_{2}O which exhibits a
ferromagnetic transition at . Extrapolating our analysis on the
basis of renormalisation group arguments, we find that this transition may
result from a very weak anisotropy effect.Comment: 8 pages, 10 Postscript figure
Anomalous Behavior of Ru for Catalytic Oxidation: A Theoretical Study of the Catalytic Reaction CO + 1/2 O_2 --> CO_2
Recent experiments revealed an anomalous dependence of carbon monoxide
oxidation at Ru(0001) on oxygen pressure and a particularly high reaction rate.
Below we report density functional theory calculations of the energetics and
reaction pathways of the speculated mechanism. We will show that the
exceptionally high rate is actuated by a weakly but nevertheless well bound
(1x1) oxygen adsorbate layer. Furthermore it is found that reactions via
scattering of gas-phase CO at the oxygen covered surface may play an important
role. Our analysis reveals, however, that reactions via adsorbed CO molecules
(the so-called Langmuir-Hinshelwood mechanism) dominate.Comment: 5 pages, 4 figures, Phys. Rev. Letters, Feb. 1997, in prin
Perfectionism and achievement goals in young Finnish ice-hockey players aspiring to make the Under-16 national team
Research on perfectionism suggests that is it useful to differentiate between perfectionistic strivings and perfectionistic concerns. Regarding the 2 x 2 achievement goal framework, the usefulness of this differentiation was recently demonstrated in a study with university student athletes (Stoeber, Stoll, Pescheck, & Otto, 2008, Study 2), in which it was found that perfectionistic strivings were associated with mastery-approach and performance-approach goals and perfectionistic concerns with mastery-avoidance, performance-approach, and performance-avoidance goals. Because the study was largely exploratory and only used non-elite athletes, the aim of the present research was to replicate and extend these findings by investigating a sample of 138 young, elite ice-hockey players, while adding further measures of perfectionism and using structural equation modelling (SEM) to confirm the relationships between perfectionistic strivings, perfectionistic concerns,and the 2 x 2 achievement goals. The SEM results showed that, in elite athletes also, perfectionistic strivings are associated with mastery-approach and performance-approach goals, whereas perfectionistic concerns are associated with masteryavoidance,
performance-approach, and performance-avoidance goals. Our findings corroborate the importance of differentiating between perfectionistic strivings and perfectionistic concerns when studying perfectionism in sports, because
only perfectionistic concerns (and not perfectionistic strivings) are associated with maladaptive patterns of achievement goals
Localized Excitons and Breaking of Chemical Bonds at III-V (110) Surfaces
Electron-hole excitations in the surface bands of GaAs(110) are analyzed
using constrained density-functional theory calculations. The results show that
Frenkel-type autolocalized excitons are formed. The excitons induce a local
surface unrelaxation which results in a strong exciton-exciton attraction and
makes complexes of two or three electron-hole pairs more favorable than
separate excitons. In such microscopic exciton "droplets" the
electron density is mainly concentrated in the dangling orbital of a surface Ga
atom whereas the holes are distributed over the bonds of this atom to its As
neighbors thus weakening the bonding to the substrate. This finding suggests
the microscopic mechanism of a laser-induced emission of neutral Ga atoms from
GaAs and GaP (110) surfaces.Comment: submitted to PRL, 10 pages, 4 figures available upon request from:
[email protected]
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