381 research outputs found
Response of Selected Exotic and Indigenous Wheat Varieties to Changes in Day Length and Temperature
Agronomy (Field Crops
Correlation-Strength Driven Anderson Metal-Insulator Transition
The possibility of driving an Anderson metal-insulator transition in the
presence of scale-free disorder by changing the correlation exponent is
numerically investigated. We calculate the localization length for
quasi-one-dimensional systems at fixed energy and fixed disorder strength using
a standard transfer matrix method. From a finite-size scaling analysis we
extract the critical correlation exponent and the critical exponent
characterizing the phase transition.Comment: 3 pages; 2 figure
Coherent manipulation of charge qubits in double quantum dots
The coherent time evolution of electrons in double quantum dots induced by
fast bias-voltage switches is studied theoretically. As it was shown
experimentally, such driven double quantum dots are potential devices for
controlled manipulation of charge qubits. By numerically solving a quantum
master equation we obtain the energy- and time-resolved electron transfer
through the device which resembles the measured data. The observed oscillations
are found to depend on the level offset of the two dots during the manipulation
and, most surprisingly, also the on initialization stage. By means of an
analytical expression, obtained from a large-bias model, we can understand the
prominent features of these oscillations seen in both the experimental data and
the numerical results. These findings strengthen the common interpretation in
terms of a coherent transfer of electrons between the dots.Comment: 18 pages, 4 figure
Dynamics of a nano-scale rotor driven by single-electron tunneling
We investigate theoretically the dynamics and the charge transport properties
of a rod-shaped nano-scale rotor, which is driven by a similar mechanism as the
nanomechanical single-electron transistor (NEMSET). We show that a static
electric potential gradient can lead to self-excitation of oscillatory or
continuous rotational motion. The relevant parameters of the device are
identified and the dependence of the dynamics on these parameters is studied.
We further discuss how the dynamics is related to the measured current through
the device. Notably, in the oscillatory regime, we find a negative differential
conductance. The current-voltage characteristics can be used to infer details
of the surrounding environment which is responsible for damping
Comment on the paper I. M. Suslov: Finite Size Scaling from the Self Consistent Theory of Localization
In the recent paper [I.M.Suslov, JETP {\bf 114} (2012) 107] a new scaling
theory of electron localization was proposed. We show that numerical data for
the quasi-one dimensional Anderson model do not support predictions of this
theory.Comment: Comment on the paper arXiv 1104.043
Spatial transcriptomics identifies spatially dysregulated expression of <i>GRM3</i> and <i>USP47</i> in amyotrophic lateral sclerosis
Research Funding Medical Research Council. Grant Number: MR/L016400/1 Biogen Academy of Medical Sciences. Grant Number: 210JMG 3102 R45620 MND Scotland Engineering and Physical Sciences Research CouncilPeer reviewedPublisher PD
Cross-Over between universality classes in a magnetically disordered metallic wire
In this article we present numerical results of conduction in a disordered
quasi-1D wire in the possible presence of magnetic impurities. Our analysis
leads us to the study of universal properties in different conduction regimes
such as the localized and metallic ones. In particular, we analyse the
cross-over between universality classes occurring when the strength of magnetic
disorder is increased. For this purpose, we use a numerical Landauer approach,
and derive the scattering matrix of the wire from electron's Green's function.Comment: Final version, accepted for publication in New Journ. of Physics, 27
pages, 28 figures. Replaces the earlier shorter preprint arXiv:0910.427
Mutational spectra of aflatoxin B
Aflatoxin Bâ (AFBâ) and/or hepatitis B and C viruses are risk factors for human hepatocellular carcinoma (HCC). Available evidence supports the interpretation that formation of AFBâ-DNA adducts in hepatocytes seeds a population of mutations, mainly G:CâT:A, and viral processes synergize to accelerate tumorigenesis, perhaps via inflammation. Responding to a need for early-onset evidence predicting disease development, highly accurate duplex sequencing was used to monitor acquisition of high-resolution mutational spectra (HRMS) during the process of hepatocarcinogenesis. Four-day-old male mice were treated with AFBâ using a regimen that induced HCC within 72 wk. For analysis, livers were separated into tumor and adjacent cellular fractions. HRMS of cells surrounding the tumors revealed predominantly G:CâT:A mutations characteristic of AFBâ exposure. Importantly, 25% of all mutations were GâT in one trinucleotide context (CGC; the underlined G is the position of the mutation), which is also a hotspot mutation in human liver tumors whose incidence correlates with AFBâ exposure. The technology proved sufficiently sensitive that the same distinctive spectrum was detected as early as 10 wk after dosing, well before evidence of neoplasia. Additionally, analysis of tumor tissue revealed a more complex pattern than observed in surrounding hepatocytes; tumor HRMS were a composite of the 10-wk spectrum and a more heterogeneous set of mutations that emerged during tumor outgrowth. We propose that the 10-wk HRMS reflects a short-term mutational response to AFBâ, and, as such, is an early detection metric for AFBâ-induced liver cancer in this mouse model that will be a useful tool to reconstruct the molecular etiology of human hepatocarcinogenesis.National Institutes of Health (U.S.) (Grant R01-ES016313)National Institutes of Health (U.S.) (Grant P30-ES002109)National Institutes of Health (U.S.) (Grant T32-ES007020)National Institutes of Health (U.S.) (Grant R01-CA080024
The Role of Power-Law Correlated Disorder in the Anderson Metal-Insulator Transition
We study the influence of scale-free correlated disorder on the
metal-insulator transition in the Anderson model of localization. We use
standard transfer matrix calculations and perform finite-size scaling of the
largest inverse Lyapunov exponent to obtain the localization length for
respective 3D tight-binding systems. The density of states is obtained from the
full spectrum of eigenenergies of the Anderson Hamiltonian. We discuss the
phase diagram of the metal-insulator transition and the influence of the
correlated disorder on the critical exponents.Comment: 6 pages, 3 figure
Anomalous lattice dynamics and thermal properties of supported size- and shape-selected Pt nanoparticles
Anomalous lattice dynamics and thermal behavior have been observed for ligand-free, size-, and shape-selected Pt nanoparticles (NPs) supported on nanocrystalline gamma-Al(2)O(3) via extended x-ray absorption fine-structure spectroscopy. Several major differences were observed for the NPs with respect to bulk Pt: (i) a contraction in the interatomic distances, (ii) a reduction in the dynamic (temperature-dependent) bond-length disorder and associated increase in the Debye temperature (theta(D)), and (iii) an overall decrease in the bond-length expansion coefficient coupled with NP stiffening. The increase in the Debye temperature is explained in terms of the NP size, shape, support interactions, and adsorbate effects. For a similar average size, we observe a striking correlation between the shapes of the NPs and their theta(D) values
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