2,938 research outputs found
Unconventional Metallicity and Giant Thermopower in a Strongly Interacting Two Dimensional Electron System
We present thermal and electrical transport measurements of low-density
(10 m), mesoscopic two-dimensional electron systems (2DESs) in
GaAs/AlGaAs heterostructures at sub-Kelvin temperatures. We find that even in
the supposedly strongly localised regime, where the electrical resistivity of
the system is two orders of magnitude greater than the quantum of resistance
, the thermopower decreases linearly with temperature indicating
metallicity. Remarkably, the magnitude of the thermopower exceeds the predicted
value in non-interacting metallic 2DESs at similar carrier densities by over
two orders of magnitude. Our results indicate a new quantum state and possibly
a novel class of itinerant quasiparticles in dilute 2DESs at low temperatures
where the Coulomb interaction plays a pivotal role.Comment: 8 pages, 8 figures (version to appear in Phys. Rev. B
Transfer-Recursive-Ensemble Learning for Multi-Day COVID-19 Prediction in India using Recurrent Neural Networks
The current COVID-19 pandemic has put a huge challenge on the Indian health
infrastructure. With more and more people getting affected during the second
wave, the hospitals were over-burdened, running out of supplies and oxygen. In
this scenario, prediction of the number of COVID-19 cases beforehand might have
helped in the better utilization of limited resources and supplies. This
manuscript deals with the prediction of new COVID-19 cases, new deaths and
total active cases for multiple days in advance. The proposed method uses gated
recurrent unit networks as the main predicting model. A study is conducted by
building four models that are pre-trained on the data from four different
countries (United States of America, Brazil, Spain and Bangladesh) and are
fine-tuned or retrained on India's data. Since the four countries chosen have
experienced different types of infection curves, the pre-training provides a
transfer learning to the models incorporating diverse situations into account.
Each of the four models then give a multiple days ahead predictions using
recursive learning method for the Indian test data. The final prediction comes
from an ensemble of the predictions of the combination of different models.
This method with two countries, Spain and Brazil, is seen to achieve the best
performance amongst all the combinations as well as compared to other
traditional regression models.Comment: 8 pages, 7 figure
A Powerful New Quantitative Genetics Platform, Combining Caenorhabditis elegans High-Throughput Fitness Assays with a Large Collection of Recombinant Strains.
The genetic variants underlying complex traits are often elusive even in powerful model organisms such as Caenorhabditis elegans with controlled genetic backgrounds and environmental conditions. Two major contributing factors are: (1) the lack of statistical power from measuring the phenotypes of small numbers of individuals, and (2) the use of phenotyping platforms that do not scale to hundreds of individuals and are prone to noisy measurements. Here, we generated a new resource of 359 recombinant inbred strains that augments the existing C. elegans N2xCB4856 recombinant inbred advanced intercross line population. This new strain collection removes variation in the neuropeptide receptor gene npr-1, known to have large physiological and behavioral effects on C. elegans and mitigates the hybrid strain incompatibility caused by zeel-1 and peel-1, allowing for identification of quantitative trait loci that otherwise would have been masked by those effects. Additionally, we optimized highly scalable and accurate high-throughput assays of fecundity and body size using the COPAS BIOSORT large particle nematode sorter. Using these assays, we identified quantitative trait loci involved in fecundity and growth under normal growth conditions and after exposure to the herbicide paraquat, including independent genetic loci that regulate different stages of larval growth. Our results offer a powerful platform for the discovery of the genetic variants that control differences in responses to drugs, other aqueous compounds, bacterial foods, and pathogenic stresses
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