32,082 research outputs found
Violation of Kohler's rule by the magnetoresistance of a quasi-two-dimensional organic metal
The interlayer magnetoresistance of the quasi-two-dimensional metal
-(BEDT-TTF)KHg(SCN) is considered. In the temperature range
from 0.5 to 10 K and for fields up to 10 tesla the magnetoresistance has a
stronger temperature dependence than the zero-field resistance. Consequently
Kohler's rule is not obeyed for any range of temperatures or fields. This means
that the magnetoresistance cannot be described in terms of semiclassical
transport on a single Fermi surface with a single scattering time. Possible
explanations for the violations of Kohler's rule are considered, both within
the framework of semi-classical transport theory and involving incoherent
interlayer transport. The issues considered are similar to those raised by the
magnetotransport of the cuprate superconductors.Comment: 5 pages, RevTeX + epsf, 2 figures. Slightly revised version to appear
in Physical Review B, May 15, 199
Directly comparing coronal and solar wind elemental fractionation
As the solar wind propagates through the heliosphere, dynamical processes
irreversibly erase the signatures of the near-Sun heating and acceleration
processes. The elemental fractionation of the solar wind should not change
during transit however, making it an ideal tracer of these processes. We aimed
to verify directly if the solar wind elemental fractionation is reflective of
the coronal source region fractionation, both within and across different solar
wind source regions. A backmapping scheme was used to predict where solar wind
measured by the Advanced Composition Explorer (ACE) originated in the corona.
The coronal composition measured by the Hinode Extreme ultraviolet Imaging
Spectrometer (EIS) at the source regions was then compared with the in-situ
solar wind composition. On hourly timescales there was no apparent correlation
between coronal and solar wind composition. In contrast, the distribution of
fractionation values within individual source regions was similar in both the
corona and solar wind, but distributions between different sources have
significant overlap. The matching distributions directly verifies that
elemental composition is conserved as the plasma travels from the corona to the
solar wind, further validating it as a tracer of heating and acceleration
processes. The overlap of fractionation values between sources means it is not
possible to identify solar wind source regions solely by comparing solar wind
and coronal composition measurements, but a comparison can be used to verify
consistency with predicted spacecraft-corona connections.Comment: Accepted version; 8 pages, 7 figure
Basic hydrogeologic and remote sensing data for selection of sanitary landfill sites
Solid waste disposal were studied in Volusia County to protect the water supply in the area. Highlands in this County are of limited areal extent and, most significantly, the sand hills and ridges are in areas where recharge of the Floridan aquifer occurs. This study proves that well drained soils meeting the current State requirements are of limited areal extent. These areas should not be utilized as sanitary landfill sites! Rather, it is recommended that the Tomoka Farm Road site into the adjacent wetlands be extended. The County site on Rima Ridge recommended by Greenleaf-Telesca as the primary waste burial site in the County should be re-evaluated because of potential danger to the Daytona Beach water supply
Hydraulics and geology related to beach restoration in Lee County, Florida
The erosion problem on Captiva Island is discussed. It is due to a deficit in the sand budget of the littoral drift system; a system with losses due to attrition of the particles and mass losses into the lagoons, to offshore, and to lateral transport. The effect that reopening Blind Pass would have, and the placement of sediment retaining structures in the surf zone at the northern and southern limits of the Captiva beach system, wave examined. A geological approach was used to study the origin and dynamic changes that have occurred. Through hydraulic modeling, changes that will occur by reopening and stabilizing Blind Pass are predicted. It is concluded that if the island is to be stabilized, beach nourishment with proper amounts and particle size is a necessity and that jetties adequate to restrict lateral and offshore losses are essential. It is shown that the reopening of Blind Pass would have minimal effects on the passes to the north and south, and would improve the environmental conditions in the sound with no adverse effects on the beach system
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