2,305 research outputs found
Kondo effect in graphene with Rashba spin-orbit coupling
We study the Kondo screening of a magnetic impurity adsorbed in graphene in
the presence of Rashba spin-orbit interaction. The system is described by an
effective single-channel Anderson impurity model, which we analyze using the
numerical renormalization group. The nontrivial energy dependence of the host
density of states gives rise to interesting behaviors under variation of the
chemical potential or the spin-orbit coupling. Varying the Rashba coupling
produces strong changes in the Kondo temperature characterizing the many-body
screening of the impurity spin, and at half filling allows approach to a
quantum phase transition separating the strong-coupling Kondo phase from a
free-moment phase. Tuning the chemical potential close to sharp features of the
hybridization function results in striking features in the temperature
dependences of thermodynamic quantities and in the frequency dependence of the
impurity spectral function.Comment: 11 pages, 9 figures. Minor changes. Accepted in PR
Personality and Values Based Materialism: Their Relationship and Origins
Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/141942/1/jcpy389.pd
Signatures of quantum phase transitions in parallel quantum dots: Crossover from local-moment to underscreened spin-1 Kondo physics
We study a strongly interacting "quantum dot 1" and a weakly interacting "dot
2" connected in parallel to metallic leads. Gate voltages can drive the system
between Kondo-quenched and non-Kondo free-moment phases separated by
Kosterlitz-Thouless quantum phase transitions. Away from the immediate vicinity
of the quantum phase transitions, the physical properties retain signatures of
first-order transitions found previously to arise when dot 2 is strictly
noninteracting. As interactions in dot 2 become stronger relative to the
dot-lead coupling, the free moment in the non-Kondo phase evolves smoothly from
an isolated spin-one-half in dot 1 to a many-body doublet arising from the
incomplete Kondo compensation by the leads of a combined dot spin-one. These
limits, which feature very different spin correlations between dot and lead
electrons, can be distinguished by weak-bias conductance measurements performed
at finite temperatures.Comment: 7 pages, 7 figures. Accepted for publication in Phys. Rev.
Multiple output samples per input in a single-output Gaussian process
The standard Gaussian Process (GP) only considers a single output sample per
input in the training set. Datasets for subjective tasks, such as spoken
language assessment, may be annotated with output labels from multiple human
raters per input. This paper proposes to generalise the GP to allow for these
multiple output samples in the training set, and thus make use of available
output uncertainty information. This differs from a multi-output GP, as all
output samples are from the same task here. The output density function is
formulated to be the joint likelihood of observing all output samples, and
latent variables are not repeated to reduce computation cost. The test set
predictions are inferred similarly to a standard GP, with a difference being in
the optimised hyper-parameters. This is evaluated on speechocean762, showing
that it allows the GP to compute a test set output distribution that is more
similar to the collection of reference outputs from the multiple human raters.Comment: This paper is presented in the "Symposium for Celebrating 40 Years of
Bayesian Learning in Speech and Language Processing and Beyond", which is a
satellite event of the ASRU workshop, on 20 December 2023.
https://bayesian40.github.io
Cultural and Situational Contingencies and the Theory of Reasoned Action: Application to Fast Food Restaurant Consumption
Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/141312/1/jcpy97.pd
Abundance And Ecological Significance Of The Clam Rangia Cuneata (Sowerby, 1831) In The Upper Barataria Estuary (Louisiana, USA)
We proposed that Rangia cuneata (Sowerby, 1831) is an important estuarine bivalve with ecological significance in three coastal lakes in Barataria Bay, Gulf of Mexico—Lake Cataouatche, Lake Salvador and Lac des Allemands. Our goals were to determine the abundance and distribution of Rangia in these lakes and to measure clearance times to elucidate its potential impacts on phytoplankton communities. The estimated average densities of R. cuneata in Lake Cataouatche, Lake Salvador, and Lac des Allemands were 63, 157, and 107 individuals m−2, respectively, which is 30% lower than that observed in nearby Lake Pontchartrain. The size of clams in Lake Salvador was between 4 and 50 mm, while individuals in Lake Cataouatche and Lac des Allemands were mostly \u3e20 mm. We postulate that a relatively infrequent large tropical storm transported the larvae from Lake Salvador to the other two lakes 1 year before our sampling to create this size difference. The clams were up to 99.9% of the total benthic biomass in Lake Salvador, 15.9% in Lake Cataouatche, and 40.0% in Lac des Allemands. The R. cuneata biomass values were between 16.2 and 27.6 g m−2 and the clearance times were 1.0–1.5 days. The clearance times are among the highest previously reported for coastal bivalve communities, which were from cooler climates. The results demonstrate that Rangia can be a critical part of the ecological processes in shallow water systems of the Gulf of Mexico
Size-Dependent Top-Down Control On Phytoplankton Growth By Microzooplankton In Eutrophic Lakes
We hypothesized that the grazing on phytoplankton by the microzooplankton community is size-dependent and, therefore, the top-down control on phytoplankton by microzooplankton community could be one possible mechanism explaining why small phytoplankton become less abundant than large phytoplankton in eutrophic waters. We tested this hypothesis using the dilution method to measure microzooplankton grazing rates and phytoplankton growth rates in the eutrophic waters of the Barataria estuary, southeastern Louisiana. Microzooplankton grazing rates on the slower growing, small phytoplankton (\5 lm) were higher than on the large phytoplankton ([20 lm) which had relatively faster growth rates. The proportional loss of the small, medium, large phytoplankton, and total phytoplankton community by microzooplankton grazing was 44, 53, 0, and 29%, respectively. The relative weakness of top-down grazing control on large phytoplankton by microzooplankton, and the relatively fast growth of large phytoplankton, may be why the average size of phytoplankton, whether isolated cells or colonies, tend to increase in these eutrophic waters and elsewhere
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