1,304 research outputs found
Universal distribution of magnetic anisotropy of impurities in ordered and disordered nano-grains
We examine the distribution of the magnetic anisotropy (MA) experienced by a
magnetic impurity embedded in a metallic nano-grain. As an example of a generic
magnetic impurity with partially filled -shell, we study the case of
impurities imbedded into ordered and disordered Au nano-grains, described in
terms of a realistic band structure. Confinement of the electrons induces a
magnetic anisotropy that is large, and can be characterized by 5 real
parameters, coupling to the quadrupolar moments of the spin. In ordered
(spherical) nano-grains, these parameters exhibit symmetrical structures and
reflect the symmetry of the underlying lattice, while for disordered grains
they are randomly distributed and, - for stronger disorder, - their
distribution is found to be characterized by random matrix theory. As a result,
the probability of having small magnetic anisotropies is suppressed below
a characteristic scale , which we predict to scale with the number of
atoms as . This gives rise to anomalies in the
specific heat and the susceptibility at temperatures and
produces distinct structures in the magnetic excitation spectrum of the
clusters, that should be possible to detect experimentally
Collective excitations and low temperature transport properties of bismuth
We examine the influence of collective excitations on the transport
properties (resistivity, magneto- optical conductivity) for semimetals,
focusing on the case of bismuth. We show, using an RPA approximation, that the
properties of the system are drastically affected by the presence of an
acoustic plasmon mode, consequence of the presence of two types of carriers
(electrons and holes) in this system. We found a crossover temperature T*
separating two different regimes of transport. At high temperatures T > T* we
show that Baber scattering explains quantitatively the DC resistivity
experiments, while at low temperatures T < T* interactions of the carriers with
this collective mode lead to a T^5 behavior of the resistivity. We examine
other consequences of the presence of this mode, and in particular predict a
two plasmon edge feature in the magneto-optical conductivity. We compare our
results with the experimental findings on bismuth. We discuss the limitations
and extensions of our results beyond the RPA approximation, and examine the
case of other semimetals such as graphite or 1T-TiSe_2
Effect of 1-methylcyclopropene on ‘Bosc Kobak’ pears
1-Methylcyclopropene (1-MCP) is the active component of the SmartFresh Quality System. By the application of the 1-MCP compound, quality of the harvested pears can be preserved longer during the normal cold storage. In our work, the effectiveness of the SmartFresh Quality System was investigated on ‘Bosc Kobak’ pears (Pyruscommunis L.) harvested at different times. The rheological changes and storage losses were measured. The effectiveness of 1-MCP depends on many variables, but our results show that the optimal harvest date and the condition of the harvested fruit are the most influential factors
Rolle der jungen Strukturbewegungen in der Reliefgestaltung des Lössrückens von Monor--Ceglédbercel
Changes of the enterprise characteristics of spatial economic structure in the north-hungarian region
In this publication I analysed the tendency of the number of people employed by enterprises that operate in the counties of the North-Hungarian region and the development of the GDP produced by such enterprises according to consolidated national economic sectors. On the basis of the analysis it can be stated that in the North-Hungarianregion, and also in Hungary as a whole, the share ofthe manufacturing industry decreased, while the share of the tertiary industry increased. As the result of this, the possibility of the economic instability in-creased, because the role of industries that ensure the stability, primarily of those which are bound to place and capital equipment, diminished and the role of the easy-to-mobilise tertiary industry appreciated. Thus, on the long term the region's economic development can only be ensured by means of economic development policy inciting continuous investments
The evolving story of medical emergency teams in quality improvement
Adverse events affect approximately 3% to 12% of hospitalized patients. At least a third, but as many as half, of such events are considered preventable. Detection of these events requires investments of time and money. A report in a recent issue of Critical Care used the medical emergency team activation as a trigger to perform a prospective standardized evaluation of charts. The authors observed that roughly one fourth of calls were related to a preventable adverse event, which is comparable to the previous literature. However, while previous studies relied on retrospective chart reviews, this study introduced the novel element of real-time characterization of events by the team at the moment of consultation. This methodology captures important opportunities for improvements in local care at a rate far higher than routine incident-reporting systems, but without requiring substantial investments of additional resources. Academic centers are increasingly recognizing engagement in quality improvement as a distinct career pathway. Involving such physicians in medical emergency teams will likely facilitate the dual roles of these as a clinical outreach arm of the intensive care unit and in identifying problems in care and leading to strategies to reduce them
Laser-Induced Thermal Acoustics Theory and Expected Experimental Errors when Applied to a Scramjet Isolator Model
A scramjet isolator model test apparatus is being assembled in the Isolator Dynamics Research Lab (IDRL) at the NASA Langley Research Center in Hampton, Virginia. The test apparatus is designed to support multiple measurement techniques for investigating the flow field in a scramjet isolator model. The test section is 1-inch high by 2-inch wide by 24-inch long and simulates a scramjet isolator with an aspect ratio of two. Unheated, dry air at a constant stagnation pressure and temperature is delivered to the isolator test section through a Mach 2.5 planar nozzle. The isolator test section is mechanically back-pressured to contain the resulting shock train within the 24-inch isolator length and supports temperature, static pressure, and high frequency pressure measurements at the wall. Additionally, nonintrusive methods including laser-induced thermal acoustics (LITA), spontaneous Raman scattering, particle image velocimetry, and schlieren imaging are being incorporated to measure off-wall fluid dynamic, thermodynamic, and transport properties of the flow field. Interchangeable glass and metallic sidewalls and optical access appendages permit making multiple measurements simultaneously. The measurements will be used to calibrate computational fluid dynamics turbulence models and characterize the back-pressured flow of a scramjet isolator. This paper describes the test apparatus, including the optical access appendages; the physics of the LITA method; and estimates of LITA measurement uncertainty for measurements of the speed of sound and temperature
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