16,907 research outputs found
Photoquenching and thermal recovery of a thermally stimulated current peak in semiâinsulating GaAs
Coordinate shift in the semiclassical Boltzmann equation and the anomalous Hall effect
We propose a gauge invariant expression for the side jump associated with
scattering between particular Bloch states. Our expression for the side jump
follows from the Born series expansion for the scattering T-matrix in powers of
the strength of the scattering potential. Given our gauge invariant side jump
expression, it is possible to construct a semiclassical Boltzmann theory of the
anomalous Hall effect which expresses all previously identified contributions
in terms of gauge invariant quantities and does not refer explicitly to
off-diagonal terms in the density-matrix response.Comment: 6 pages, 1 fugure. submitted to PR
Quantum transport through a double Aharonov-Bohm-interferometer in the presence of Andreev reflection
Quantum transport through a double Aharonov-Bohm-interferometer in the
presence of Andreev reflection is investigated in terms of the nonequilibrium
Green function method with which the reflection current is obtained. Tunable
Andreev reflection probabilities depending on the interdot coupling strength
and magnetic flux as well are analysised in detail. It is found that the
oscillation period of the reflection probability with respect to the magnetic
flux for the double interferometer depends linearly on the ratio of two parts
magnetic fluxes n, i.e. 2(n+1)pi, while that of a single interferometer is 2pi.
The coupling strength not only affects the height and the linewidth of Andreev
reflection current peaks vs gate votage but also shifts the peak positions. It
is furthermore demonstrated that the Andreev reflection current peaks can be
tuned by the magnetic fluxes.Comment: 13 pages, 12 figur
Nonorthogonal decoy-state Quantum Key Distribution
In practical quantum key distribution (QKD), weak coherent states as the
photon sources have a limit in secure key rate and transmission distance
because of the existence of multiphoton pulses and heavy loss in transmission
line. Decoy states method and nonorthogonal encoding protocol are two important
weapons to combat these effects. Here, we combine these two methods and propose
a efficient method that can substantially improve the performance of QKD. We
find a 79 km increase in transmission distance over the prior record using
decoy states method.Comment: 4 pages, 1 figure; Revtex4, submitted to PR
Crashworthiness design of a steelâaluminum hybrid rail using multi-response objective-oriented sequential optimization
© 2017 Elsevier Ltd Hybrid structures with different materials have aroused increasing interest for their lightweight potential and excellent performances. This study explored the optimization design of steelâaluminum hybrid structures for the highly nonlinear impact scenario. A metamodel based multi-response objective-oriented sequential optimization was adopted, where Kriging models were updated with sequential training points. It was indicated that the sequential sampling strategy was able to obtain a much higher local accuracy in the neighborhood of the optimum and thus to yield a better optimum, although it did lead to a worse global accuracy over the entire design space. Furthermore, it was observed that the steelâaluminum hybrid structure was capable of decreasing the peak force and simultaneously enhancing the energy absorption, compared to the conventional mono-material structure
From building to city level dynamic digital Twin: A review from data management perspective
The development of the digital twin (DT) has been focused greatly after the concept was brought from the manufacturing and aerospace areas. In the architectural, engineering, construction and facility management (AEC/FM) sector, DTs are capable of integrating heterogeneous metadata and cutting-edge technologies like artificial intelligence and machine learning to create a dynamic digital environment for various purposes. Although building information modelling (BIM) appears to be a significant contributor to DTs, one of the major limitations for DT development is how to construct and provide a shared data environment for all stakeholders to collaborate throughout the life cycle. Furthermore, as the stakeholders' requirements range of DTs expands from a single building to multiple buildings and regional/city levels, the information and data management gaps (e.g., BIM and GIS data integration) are more challenging and critical. To address these gaps, this paper aims to 1) review the current data management for building and city level DTs from a technical perspective; 2) summarise their major data management issues from building to city levels based on the review; 3) introduce the concept of city-level Common Data Environment (CDE) that addresses the issues identified above, and discuss the possibilities of developing a CDE for a dynamic city-level DT
Two Novel Genetic Variants in the Mineralocorticoid Receptor Gene Associated with Spontaneous Preterm Birth
Background: Preterm birth is the leading cause of mortality and morbidity in newborn infants. Its etiology is multifactorial with genes and environmental factors, including chronic maternal stress, contributing to its risk. Our objective was to investigate whether single nucleotide polymorphisms (SNPs) in genes involved in the stress response are associated with spontaneous preterm birth using a candidate gene approach.
Methods: A total of 210 cases (singleton spontaneous preterm birth at \u3c37 \u3eweeks) and 412 controls (singleton term birth at 38â42 weeks without a history of preterm birth) were studied. High quality maternal DNA was available from saliva samples of 190 cases and 369 controls and compared. Sociodemographic and medical data were collected. Sixteen SNPs, either tag SNPs located in key genes involved in the stress response identified in the Preterm Birth Genome Project database or SNPs found to be associated with adverse mental health outcomes in the published literature, were selected for genotyping and sequencing. SNPs were genotyped using TaqmanÂź SNP genotyping assays. Univariate and multivariate logistic regression were performed.
Results: Multivariate analysis showed that two SNPs located in the mineralocorticoid receptor gene were significantly associated with spontaneous preterm birth: rs17484063 (OR 0.50, p = 0.038) and rs2883929 (OR 0.49, p = 0.017), regardless of maternal age, smoking, alcohol use, educational status, and history of spontaneous miscarriage.
Conclusion: This report demonstrates an association between mineralocorticoid receptor gene polymorphisms, rs17484063 and rs2883929, and preterm birth, supporting a role for genetics in the association between chronic maternal stress and preterm birth. Potentially, this information may be used to predicting the risk of having a preterm delivery
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