1,793 research outputs found
Proximity of the superconducting dome and the quantum critical point in the two-dimensional Hubbard model
We use the dynamical cluster approximation to understand the proximity of the superconducting dome to the quantum critical point in the two-dimensional Hubbard model. In a BCS formalism, Tc may be enhanced through an increase in the d-wave pairing interaction (Vd) or the bare pairing susceptibility (χ0d). At optimal doping, where Vd is revealed to be featureless, we find a power-law behavior of χ 0d(ω=0), replacing the BCS log, and strongly enhanced T c. We suggest experiments to verify our predictions. © 2011 American Physical Society
Aluminum Oxide Layers as Possible Components for Layered Tunnel Barriers
We have studied transport properties of Nb/Al/AlOx/Nb tunnel junctions with
ultrathin aluminum oxide layers formed by (i) thermal oxidation and (ii) plasma
oxidation, before and after rapid thermal post-annealing of the completed
structures at temperatures up to 550 deg C. Post-annealing at temperatures
above 300 deg C results in a significant decrease of the tunneling conductance
of thermally-grown barriers, while plasma-grown barriers start to change only
at annealing temperatures above 450 deg C. Fitting the experimental I-V curves
of the junctions using the results of the microscopic theory of direct
tunneling shows that the annealing of thermally-grown oxides at temperatures
above 300 deg C results in a substantial increase of their average tunnel
barriers height, from ~1.8 eV to ~2.45 eV, versus the practically unchanged
height of ~2.0 eV for plasma-grown layers. This difference, together with high
endurance of annealed barriers under electric stress (breakdown field above 10
MV/cm) may enable all-AlOx and SiO2/AlOx layered "crested" barriers for
advanced floating-gate memory applications.Comment: 7 pages, 6 figure
Constraints on Spin-Independent Nucleus Scattering with sub-GeV Weakly Interacting Massive Particle Dark Matter from the CDEX-1B Experiment at the China Jin-Ping Laboratory
We report results on the searches of weakly interacting massive particles
(WIMPs) with sub-GeV masses () via WIMP-nucleus spin-independent
scattering with Migdal effect incorporated. Analysis on time-integrated (TI)
and annual modulation (AM) effects on CDEX-1B data are performed, with 737.1
kgday exposure and 160 eVee threshold for TI analysis, and 1107.5
kgday exposure and 250 eVee threshold for AM analysis. The sensitive
windows in are expanded by an order of magnitude to lower DM masses
with Migdal effect incorporated. New limits on at
90\% confidence level are derived as 1010
for TI analysis at 50180 MeV/, and
1010 for AM analysis at
75 MeV/3.0 GeV/.Comment: 5 pages, 4 figure
Left-right asymmetry for pion and kaon production in the semi-inclusive deep inelastic scattering process
We analyze the left-right asymmetry in the semi-inclusive deep inelastic
scattering (SIDIS) process without introducing any weighting functions. With
the current theoretical understanding, we find that the Sivers effect plays a
key role in our analysis. We use the latest parametrization of the Sivers and
fragmentation functions to reanalyze the production process and find
that the results are sensitive to the parametrization. We also extend our
calculation on the production, which can help us know more about the
Sivers distribution of the sea quarks and the unfavored fragmentation
processes. HERMES kinematics with a proton target, COMPASS kinematics with a
proton, deuteron, and neutron target (the information on the neutron target can
be effectively extracted from the He target), and JLab kinematics (both 6
GeV and 12 GeV) with a proton and neutron target are considered in our paper.Comment: 7 latex pages, 11 figures, final version for publication, with
references update
Search for Light Weakly-Interacting-Massive-Particle Dark Matter by Annual Modulation Analysis with a Point-Contact Germanium Detector at the China Jinping Underground Laboratory
We present results on light weakly interacting massive particle (WIMP)
searches with annual modulation (AM) analysis on data from a 1-kg mass -type
point-contact germanium detector of the CDEX-1B experiment at the China Jinping
Underground Laboratory. Datasets with a total live time of 3.2 yr within a 4.2
yr span are analyzed with analysis threshold of 250 eVee. Limits on
WIMP-nucleus (-) spin-independent cross sections as function of WIMP
mass () at 90\% confidence level (C.L.) are derived using the dark
matter halo model. Within the context of the standard halo model, the 90\% C.L.
allowed regions implied by the DAMA/LIBRA and CoGeNT AM-based analysis are
excluded at 99.99\% and 98\% C.L., respectively. These results correspond to
the best sensitivity at 6 among WIMP AM
measurements to date.Comment: 5 pages, 4 figure
New insights into the evolution of wheat avenin-like proteins in wild emmer wheat (Triticum dicoccoides)
Fifteen full-length wheat grain avenin-like protein coding genes (TaALP) were identified on chromosome arms 7AS, 4AL, and 7DS of bread wheat with each containing five genes. Besides the a- and b-type ALPs, a c type was identified in the current paper. Both a and b types have two subunits, named x and y types. The five genes on each of the three chromosome arms consisted of two x-type genes, two y-type genes, and one c-type gene. The a-type genes were typically of 520 bp in length, whereas the b types were of 850 bp in length, and the c type was of 470 bp in length. The ALP gene transcript levels were significantly up-regulated in Blumeria graminis f. sp. tritici (Bgt)-infected wheat grain caryopsis at early grain filling. Wild emmer wheat [(WEW), Triticum dicoccoides] populations were focused on in our paper to identify allelic variations of ALP genes and to study the influence of natural selection on certain alleles. Consequently, 25 alleles were identified for TdALP-bx-7AS, 13 alleles were identified for TdALP-ax-7AS, 7 alleles were identified for TdALP-ay-7AS, and 4 alleles were identified for TdALP-ax-4AL. Correlation studies on TdALP gene diversity and ecological stresses suggested that environmental factors contribute to the ALP polymorphism formation in WEW. Many allelic variants of ALPs in the endosperm of WEW are not present in bread wheat and therefore could be utilized in breeding bread wheat varieties for better quality and elite plant defense characteristics
An Intersecting Loop Model as a Solvable Super Spin Chain
In this paper we investigate an integrable loop model and its connection with
a supersymmetric spin chain. The Bethe Ansatz solution allows us to study some
properties of the ground state. When the loop fugacity lies in the physical
regime, we conjecture that the central charge is for integer .
Low-lying excitations are examined, supporting a superdiffusive behavior for
. We argue that these systems are interesting examples of integrable
lattice models realizing conformal field theories.Comment: latex file, 7 page
Wheat avenin-like protein and its significant Fusarium Head Blight resistant functions
Wheat Avenin-like proteins (TaALP) are atypical storage proteins belonging to the Prolamin superfamily. Previous studies on ALPs have focused on the proteins’ positive effects on dough strength, whilst no correlation has been made between TaALPs and the plant immune system. Here, we performed genome-wide characterization of ALP encoding genes in bread wheat. In silico analyses indicated the presence of critical peptides in TaALPs that are active in the plant immune system. Pathogenesis-related nucleotide motifs were also identified in the putative promoter regions of TaALP encoding genes. RT-PCR was performed on TaALP and previously characterised pathogenesis resistance genes in developing wheat caryopses under control and Fusarium graminearum infection conditions. The results showed that TaALP and NMT genes were upregulated upon F. graminearum inoculation. mRNA insitu hybridization showed that TaALP genes were expressed in the embryo, aleurone and sub-aleurone layer cells. Seven TaALP genes were cloned for the expression of recombinant proteins in Escherichia coli, which displayed significant inhibitory function on F. graminearum under anti-fungal tests. In addition, FHB index association analyses showed that allelic variations of two ALP genes on chromosome 7A were significantly correlated with FHB symptoms. Over-expression of an ALP gene on chromosome 7A showed an enhanced resistance to FHB. Yeast two Hybridization results revealed that ALPs have potential proteases inhibiting effect on metacaspases and beta-glucosidases. A vital infection process related pathogen protein, F. graminearum Beta-glucosidase was found to interact with ALPs. Our study is the first to report a class of wheat storage protein or gluten protein with biochemical functions. Due to its abundance in the grain and the important multi-functions, the results obtained in the current study are expected to have a significant impact on wheat research and industry
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