2,681 research outputs found
Probable Displacement of Riffle-Dwelling Invertebrates by the Introduced Rusty Crayfish, \u3ci\u3eOrconectes Rusticus\u3c/i\u3e (Decapoda: Cambaridae) in a North-Central Wisconsin Stream
The rapid northward range expansion of the rusty crayfish, Orconectes rusticus, and its negative effects on Wisconsin lakes have been the subjects of intense study throughout the last fifteen years. In this study, we investigated the possible impact of rusty crayfish on the benthic macroinvertebrate community structure of the Prairie River in north-central Wisconsin. Rusty crayfish and other invertebrates were collected during August and September, 1994, from three sections of the Prairie River. Rusty crayfish relative abundance increased significantly from the upper to middle, and middle to lower sections; and correlated negatively with a significant 77% decrease in total density of aquatic invertebrates between sections. Mean density of all important invertebrate families and trophic guilds decreased significantly between the upper and lower sections. Due to the similarity of most environmental conditions between river sections, decrease of invertebrates is attributed to the increased abundance of rusty crayfish and its interactions with the native rouna. Our results suggest that a high abundance of rusty crayfish may negatively impact Wisconsin lotic systems
Cloud and ice in the planetary scale circulation and in climate
The roles of the cryosphere, and of cloud-radiative interactions are investigated. The effects clouds and ice have in the climate system are examined. The cloud radiation research attempts explain the modes of interaction (feedback) between raditive transfer, cloud formation, and atmospheric dynamics. The role of sea ice in weather and climate is also discussed. Models are used to describe the ice and atmospheric dynamics under study
Weak Field Hall Resistance and Effective Carrier Density Through Metal-Insulator Transition in Si-MOS Structures
We studied the weak field Hall voltage in 2D electron layers in Si-MOS
structures with different mobilities, through the metal-insulator transition.
In the vicinity of the critical density on the metallic side of the transition,
we have found weak deviations (about 6-20 %) of the Hall voltage from its
classical value. The deviations do not correlate with the strong temperature
dependence of the diagonal resistivity rho_{xx}(T). The smallest deviation in
R_{xy} was found in the highest mobility sample exhibiting the largest
variation in the diagonal resistivity \rho_{xx} with temperature (by a factor
of 5).Comment: 4 pages, 4 figures, RevTe
Probable Displacement of Riffle-Dwelling Invertebrates by the Introduced Rusty Crayfish, \u3ci\u3eOrconectes Rusticus\u3c/i\u3e (Decapoda: Cambaridae) in a North-Central Wisconsin Stream
The rapid northward range expansion of the rusty crayfish, Orconectes rusticus, and its negative effects on Wisconsin lakes have been the subjects of intense study throughout the last fifteen years. In this study, we investigated the possible impact of rusty crayfish on the benthic macroinvertebrate community structure of the Prairie River in north-central Wisconsin. Rusty crayfish and other invertebrates were collected during August and September, 1994, from three sections of the Prairie River. Rusty crayfish relative abundance increased significantly from the upper to middle, and middle to lower sections; and correlated negatively with a significant 77% decrease in total density of aquatic invertebrates between sections. Mean density of all important invertebrate families and trophic guilds decreased significantly between the upper and lower sections. Due to the similarity of most environmental conditions between river sections, decrease of invertebrates is attributed to the increased abundance of rusty crayfish and its interactions with the native rouna. Our results suggest that a high abundance of rusty crayfish may negatively impact Wisconsin lotic systems
Magnetoresistance of composite fermions at \nu=1/2
We have studied temperature dependence of both diagonal and Hall resistivity
in the vicinity of . Magnetoresistance was found to be positive and
almost independent of temperature: temperature enters resistivity as a
logarithmic correction. At the same time, no measurable corrections to the Hall
resistivity has been found. Neither of these results can be explained within
the mean-field theory of composite fermions by an analogy with conventional
low-field interaction theory. There is an indication that interactions of
composite fermions with fluctuations of the gauge field may reconcile the
theory and experiment.Comment: 9 pages, 4 figure
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Assignment of the Human TYRP (brown) Locus to Chromosome Region 9p23 by Nonradioactive in Situ Hybridization
The TYRP (brown) locus determines pigmentation and coat color in the mouse. The human homolog of the TYRP locus has been recently identified and shown to encode a 75-KDA transmembrane melanosomal glycoprotein called gp75. The gp 75 glycoprotein is homologous to tyrosinase, an enzyme in evolved in the synthesis of melanin, forming a family of tyrosinase-related proteins. A genomic clone of human gp75 was used to map the human TYRP locus to chromosome 9, region 9p23, by nonradioactive fluorescent in situ hybridization. Specificity of hybridization was tested with a genomic fragment of hu- man tyrosinase that mapped to a distinct site on 1lq2 1. The 9p region has been reported to be nonrandomly altered in human melanoma, suggesting a role for the region near the TYRP locus in melanocyte transformation
Cosmological Avatars of the Landscape I: Bracketing the SUSY Breaking Scale
We investigate the effects of quantum entanglement between our horizon patch
and others due to the tracing out of long wavelength modes in the wavefunction
of the Universe as defined on a particular model of the landscape. In this, the
first of two papers devoted to this topic, we find that the SUSY breaking scale
is bounded both above {\em and} below: for scale inflation. The lower bound is at least five
orders of magnitude larger than the expected value of this parameter and can be
tested by LHC physics.Comment: 7 pages, 1 figur
The bubbles of matter from multiskyrmions
The multiskyrmions with large baryon number B given by rational map (RM)
ansaetze can be described reasonably well within the domain wall approximation,
or as spherical bubbles with energy and baryon number density concentrated at
their boundary. A special class of profile functions is considered
approximating the true profile and domain wall behaviour at the same time. An
upper bound is obtained for the masses of RM multiskyrmions which is close to
the calculated masses, especially at large B. The gap between rigorous upper
and lower bounds for large B multiskyrmions is less than 4%. The basic
properties of such bubbles of matter are investigated, some of them being of
universal character, i.e. they do not depend on baryon number of configuration
and on the number of flavors. As a result, the lagrangian of the Skyrme type
models provides field theoretical realization of the bag model of special kind.Comment: 7 pages, no figure
Parabolic negative magnetoresistance in p-Ge/Ge1-xSix heterostructures
Quantum corrections to the conductivity due to the weak localization (WL) and
the disorder-modified electron-electron interaction (EEI) are investigated for
the high-mobility multilayer p-Ge/Ge1-xSix heterostructures at T = (0.1 -
20.0)K in magnetic field B up to 1.5T. Negative magnetoresistance with
logarithmic dependence on T and linear in B^2 is observed for B >= 0.1T. Such a
behavior is attributed to the interplay of the classical cyclotron motion and
the EEI effect. The Hartree part of the interaction constant is estimated
(F_/sigma = 0.44) and the WL and EEI contributions to the total quantum
correction /Delta /sigma at B = 0 are separated (/Delta /sigma_{WL} ~ 0.3/Delta
/sigma; /Delta /sigma_{EEI} ~ 0.7/Delta /sigma).Comment: 3 pages, 4 figure
Magnetoresistance and Hall Constant of Composite Fermions
We consider both disorder and interaction effects on the magnetoresistance
and Hall constant of composite fermions in the vicinity of half filled Landau
level. By contrast to the standard case of Coulomb interacting two-dimensional
electron gas we find logarithmic temperature corrections to the Hall
conductivity and the magnetoresistance of composite fermions whereas the Hall
constant acquires no such correction in the lowest order. The theory provides a
possible explanation of the resistivity minimum at filling factor .Comment: Latex, 11 pages, Nordita repor
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