1,969 research outputs found
Corrector theory for MsFEM and HMM in random media
We analyze the random fluctuations of several multi-scale algorithms such as
the multi-scale finite element method (MsFEM) and the finite element
heterogeneous multiscale method (HMM), that have been developed to solve
partial differential equations with highly heterogeneous coefficients. Such
multi-scale algorithms are often shown to correctly capture the homogenization
limit when the highly oscillatory random medium is stationary and ergodic. This
paper is concerned with the random fluctuations of the solution about the
deterministic homogenization limit. We consider the simplified setting of the
one dimensional elliptic equation, where the theory of random fluctuations is
well understood. We develop a fluctuation theory for the multi-scale algorithms
in the presence of random environments with short-range and long-range
correlations. What we find is that the computationally more expensive method
MsFEM captures the random fluctuations both for short-range and long-range
oscillations in the medium. The less expensive method HMM correctly captures
the fluctuations for long-range oscillations and strongly amplifies their size
in media with short-range oscillations. We present a modified scheme with an
intermediate computational cost that captures the random fluctuations in all
cases.Comment: 41 page
Electrostatic tuning of magnetism at the conducting (111) (LaSr)(AlTa)/SrTiO interface
We present measurements of the low temperature electrical transport
properties of the two dimensional carrier gas that forms at the interface of
(LaSr)(AlTa)/SrTiO (LSAT/STO) as
a function of applied back gate voltage, . As is found in (111)
LaAlO/SrTiO interfaces, the low-field Hall coefficient is
electron-like, but shows a sharp reduction in magnitude below 20 V,
indicating the presence of hole-like carriers in the system. This same value of
correlates approximately with the gate voltage below which the
magnetoresistance evolves from nonhysteretic to hysteretic behavior at
millikelvin temperatures, signaling the onset of magnetic order in the system.
We believe our results can provide insight into the mechanism of magnetism in
SrTiO based systems.Comment: 5 pages, 3 figure
Kawasaki disease following Rocky Mountain spotted fever: a case report
<p>Abstract</p> <p>Introduction</p> <p>Kawasaki disease is an idiopathic acute systemic vasculitis of childhood. Although it simulates the clinical features of many infectious diseases, an infectious etiology has not been established. This is the first reported case of Kawasaki disease following Rocky Mountain spotted fever.</p> <p>Case presentation</p> <p>We report the case of a 4-year-old girl who presented with fever and petechial rash. Serology confirmed Rocky Mountain spotted fever. While being treated with intravenous doxycycline, she developed swelling of her hands and feet. She had the clinical features of Kawasaki disease which resolved after therapy with intravenous immune globulin (IVIG) and aspirin.</p> <p>Conclusion</p> <p>This case report suggests that Kawasaki disease can occur concurrently or immediately after a rickettsial illness such as Rocky Mountain spotted fever, hypothesizing an antigen-driven immune response to a rickettsial antigen.</p
Workplace flexibility across the lifespan
As demographic changes impact the workplace, governments, organizations and workers arelooking for ways to sustain optimal working lives at higher ages. Workplace flexibility has beenintroduced as a potential way workers can have more satisfying working lives until theirretirement ages. This paper presents a critical review of the literature on workplace flexibilityacross the lifespan. It discusses how flexibility has been conceptualized across differentdisciplines, and postulates a definition that captures the joint roles of employer and employee innegotiating workplace flexibility that contributes to both employee and organization benefits.Moreover, it reviews how flexibility has been theorized and investigated in relation to olderworkers. The paper ends with a future research agenda for advancing understanding of howworkplace flexibility may enhance working experiences of older workers, and in particularfocuses on the critical investigation of uses of flexibility in relation to older workers
Kinetic Limit for Wave Propagation in a Random Medium
We study crystal dynamics in the harmonic approximation. The atomic masses
are weakly disordered, in the sense that their deviation from uniformity is of
order epsilon^(1/2). The dispersion relation is assumed to be a Morse function
and to suppress crossed recollisions. We then prove that in the limit epsilon
to 0 the disorder averaged Wigner function on the kinetic scale, time and space
of order epsilon^(-1), is governed by a linear Boltzmann equation.Comment: 71 pages, 3 figure
Regulatory Futures in Retrospect
In our 1998 volume ‘The Politics of Chemical Risk: Scenarios for a regulatory Future’ we envisioned four ideal typical scenarios for the future of European chemicals policies. The scenarios focused on the nature of expertise (seen either as a universal or a localised phenomenon) and the organisation of the boundary between science and policy (as either diverging or converging). The four scenarios were titled International Experts, European Risk Consultation, European Coordination of Assessment, and Europe as a Translator. For all four scenarios, we hypothesized internal dynamics and articulated dilemmas related to the development of the sciences contributing to chemical assessment, the relation between the EU and member states and the role of the public. In this contribution, we look back on our four scenarios fifteen years later, to see which ones have materialized and to explore whether the dilemmas we saw have indeed surfaced. We conclude that the International Experts scenario by and large has materialized and explore some of the underlying tensions and dynamics in this development
Radiation- and Phonon-Bottleneck-Induced Tunneling in the Fe8 Single-Molecule Magnet
We measure magnetization changes in a single crystal of the single-molecule
magnet Fe8 when exposed to intense, short (<20 s) pulses of microwave
radiation resonant with the m = 10 to 9 transition. We find that radiation
induces a phonon bottleneck in the system with a time scale of ~5 s. The
phonon bottleneck, in turn, drives the spin dynamics, allowing observation of
thermally assisted resonant tunneling between spin states at the 100-ns time
scale. Detailed numerical simulations quantitatively reproduce the data and
yield a spin-phonon relaxation time of T1 ~ 40 ns.Comment: 6 RevTeX pages, including 4 EPS figures, version accepted for
publicatio
Experimental Upper Bound on Superradiance Emission from Mn12 Acetate
We used a Josephson junction as a radiation detector to look for evidence of
the emission of electromagnetic radiation during magnetization avalanches in a
crystal assembly of Mn_12-Acetate. The crystal assembly exhibits avalanches at
several magnetic fields in the temperature range from 1.8 to 2.6 K with
durations of the order of 1 ms. Although a recent study shows evidence of
electromagnetic radiation bursts during these avalanches [J. Tejada, et al.,
Appl. Phys. Lett. {\bf 84}, 2373 (2004)], we were unable to detect any
significant radiation at well-defined frequencies. A control experiment with
external radiation pulses allows us to determine that the energy released as
radiation during an avalanche is less than 1 part in 10^4 of the total energy
released. In addition, our avalanche data indicates that the magnetization
reversal process does not occur uniformly throughout the sample.Comment: 4 RevTeX pages, 3 eps figure
Effect of Spacing on Canopy Microclimate, Vegetative Growth and Yield Attributes in Guava (Psidium guajava L.)
The present investigation was conducted to examine the effect of spacing on variation in canopy microclimate, vegetative growth and yield attributes in guava (cv. Allahabad Safeda). Oservations revealed that with wide plant spacing (from 6x2m to 6x4m), interception of solar radiation increased significantly. Similarly, with increase in spacing between plants, mean canopy temperature was need to increase while relative humidity decreased. Plant growth in terms of stock and scion girth, tree spread (N-S) and canopy volume increased with wide plant spacing, while tree height decreased with increase in plant spacing. Number of fruits per plant, yield per plant and fruiting density was higher at 6x5m and least in 6x2m spacing. Wider plant spacing was found to be better owing to maximum absorption of solar radiation and optimum microclimate in the orchard leading to better yield in plants, higher fruiting density and yield efficiency. However, yield/ha was maximum in 6x2m spacing during rainy season and in 6x3m spacing during winter
Ethnomedicine in Himalaya: a case study from Dolpa, Humla, Jumla and Mustang districts of Nepal
Traditional plant use in Nepal has been documented for millennia. The importance of plants as medicine has not diminished in any way in recent times, and traditional medicines are still the most important health care source for the vast majority of the population. This paper examines the ethnobotany and traditional use of plants extracted from the vulnerable alpine zone in the Dolpa, Humla, Jumla and Mustang districts of Nepal. The results of this ethnobotanical study indicate that a very large number of plant species is used as traditional medicines. There were 107, 59, 44 and 166 species of ethnomedicinal importance in surveyed areas of Dolpa, Humla, Jumla and Mustang district respectively. Of these, 84 common species, used at least in two districts, were selected to enumerate their ethnomedicinal properties. The 84 species belonged to 75 genera and 39 families. The commonest species in this pharmacopoeia were: Allium wallichii, Cordyceps sinensis, Dactylorhiza hatagirea, and Rheum australe. A total of 21 species were most common in three districts and 59 in two districts. The genera Aconitum, Allium, Arisaema, Berberis, Corydalis, Gentiana, Hippophae, Juniperus and Rhododendron each possessed two species with ethnomedicinal use. Labiatae was the most medicinally important family with five species used, followed by Araceae, Compositae, Liliaceae, Polygonaceae, Ranunculaceae, Scrophulariaceae and Umbelliferae, each contributing four species
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