861 research outputs found
Optimal entanglement witnesses based on local orthogonal observables
We show that the entanglement witnesses based on local orthogonal observables
which are introduced in [S. Yu and N.-L. Liu, Phys. Rev. Lett. 95, 150504
(2005)] and [O. G\"uhne, M. Mechler, G. T\'oth and P. Adam, Phys. Rev. A 74,
010301 (2006)] in linear and nonlinear forms can be optimized, respectively. As
applications, we calculate the optimal nonlinear witnesses of pure bipartite
states and show a lower bound on the I-concurrence of bipartite higher
dimensional systems with our method.Comment: 6 pages, 1 figure; minor changes, references adde
Photoinhibition and photoinhibition-like damage to the photosynthetic apparatus in tobacco leaves induced by pseudomonas syringae pv. Tabaci under light and dark conditions
BACKGROUND:
Pseudomonas syringae pv. tabaci (Pst), which is the pathogen responsible for tobacco wildfire disease, has received considerable attention in recent years. The objective of this study was to clarify the responses of photosystem I (PSI) and photosystem II (PSII) to Pst infection in tobacco leaves.
RESULTS:
The net photosynthetic rate (Pn) and carboxylation efficiency (CE) were inhibited by Pst infection. The normalized relative variable fluorescence at the K step (W
k) and the relative variable fluorescence at the J step (V
J) increased while the maximal quantum yield of PSII (F
v/F
m) and the density of Q
A-reducing PSII reaction centers per cross section (RC/CSm) decreased, indicating that the reaction centers, and the donor and acceptor sides of PSII were all severely damaged after Pst infection. The PSI activity decreased as the infection progressed. Furthermore, we observed a considerable overall degradation of PsbO, D1, PsaA proteins and an over-accumulation of reactive oxygen species (ROS).
CONCLUSIONS:
Photoinhibition and photoinhibition-like damage were observed under light and dark conditions, respectively, after Pst infection of tobacco leaves. The damage was greater in the dark. ROS over-accumulation was not the primary cause of the photoinhibition and photoinhibition-like damage. The PsbO, D1 and PsaA proteins appear to be the targets during Pst infection under light and dark conditions.This work was supported by the Fundamental Research Funds for the
Central Universities (No. 2572014AA18), China National Nature Science
Foundation (No. 31070307) and Outstanding Academic Leaders for
Innovation Talents of Science and Technology of Harbin City in Heilongjiang
Province (No. 2013RFXXJ063)
Type-II Topological Dirac Semimetals: Theory and Materials Prediction (VAl3 family)
The discoveries of Dirac and Weyl semimetal states in spin-orbit compounds
led to the realizations of elementary particle analogs in table-top
experiments. In this paper, we propose the concept of a three-dimensional
type-II Dirac fermion and identify a new topological semimetal state in the
large family of transition-metal icosagenides, MA3 (M=V, Nb, Ta; A=Al, Ga, In).
We show that the VAl3 family features a pair of strongly Lorentz-violating
type-II Dirac nodes and that each Dirac node consists of four type-II Weyl
nodes with chiral charge +/-1 via symmetry breaking. Furthermore, we predict
the Landau level spectrum arising from the type-II Dirac fermions in VAl3 that
is distinct from that of known Dirac semimetals. We also show a topological
phase transition from a type-II Dirac semimetal to a quadratic Weyl semimetal
or a topological crystalline insulator via crystalline distortions. The new
type-II Dirac fermions, their novel magneto-transport response, the topological
tunability and the large number of compounds make VAl3 an exciting platform to
explore the wide-ranging topological phenomena associated with
Lorentz-violating Dirac fermions in electrical and optical transport,
spectroscopic and device-based experiments.Comment: 28 pages, 7 Figure
Mirror protected Dirac fermions on a Weyl semimetal NbP surface
The first Weyl semimetal was recently discovered in the NbP class of
compounds. Although the topology of these novel materials has been identified,
the surface properties are not yet fully understood. By means of scanning
tunneling spectroscopy, we find that NbPs (001) surface hosts a pair of Dirac
cones protected by mirror symmetry. Through our high resolution spectroscopic
measurements, we resolve the quantum interference patterns arising from these
novel Dirac fermions, and reveal their electronic structure, including the
linear dispersions. Our data, in agreement with our theoretical calculations,
uncover further interesting features of the Weyl semimetal NbPs already exotic
surface. Moreover, we discuss the similarities and distinctions between the
Dirac fermions here and those in topological crystalline insulators in terms of
symmetry protection and topology
Hybrid nature of 0846+51W1: a BL Lac object with a narrow line Seyfert 1 nucleus
We have found a NLS1 nucleus in the extensively studied eruptive BL Lac,
0846+51W1, out of a large sample of NLS1 compiled from the spectroscopic
dataset of SDSS DR1. Its optical spectrum can be well decomposed into three
components, a power law component from the relativistic jet, a stellar
component from the host galaxy, and a component from a typical NLS1 nucleus.
The emission line properties of 0846+51W1, FWHM(Hbeta) ~ 1710 km s^-1 and
[OIII]5007/Hbeta ~ 0.32 when it was in faint state, fulfil the conventional
definition of NLS1. Strong FeII emission is detected in the SDSS spectrum,
which is also typical of NLS1s. We try to estimate its central black hole mass
using various techniques and find that 0846+51W1 is very likely emitting at a
few times 10% L_Edd. We speculate that Seyfert-like nuclei, including NLS1s,
might be concealed in a significant fraction of BL Lacs but have not been
sufficiently explored due to the fact that, by definition, the optical-UV
continuum of such kind of objects are often overwhelmed by the synchrotron
emission.Comment: ChJAA accepte
Variations and Determinants of Hospital Costs for Acute Stroke in China
BACKGROUND: The burden of stroke is high and increasing in China. We modelled variations in, and predictors of, the costs of hospital care for patients with acute stroke in China. METHODS AND FINDINGS: Baseline characteristics and hospital costs for 5,255 patients were collected using the prospective register-based ChinaQUEST study, conducted in 48 Level 3 and 14 Level 2 hospitals in China during 2006-2007. Ordinary least squares estimation was used to determine factors associated with hospital costs. Overall mean cost of hospitalisation was 11,216 Chinese Yuan Renminbi (CNY) (≈US$1,602) per patient, which equates to more than half the average annual wage in China. Variations in cost were largely attributable to stroke severity and length of hospital stay (LOS). Model forecasts showed that reducing LOS from the mean of 20 days for Level 3 and 18 days for Level 2 hospitals to a duration of 1 week, which is common among Western countries, afforded cost reductions of 49% and 19%, respectively. Other lesser determinants varied by hospital level: in Level 3 hospitals, health insurance and the occurrence of in-hospital complications were each associated with 10% and 18% increases in cost, respectively, whilst treatment in a teaching hospital was associated with approximately 39% decrease in cost on average. For Level 2 hospitals, stroke due to intracerebral haemorrhage was associated with a 19% greater cost than for ischaemic stroke. CONCLUSIONS: Changes to hospital policies to standardise resource use and reduce the variation in LOS could attenuate costs and improve efficiencies for acute stroke management in China. The success of these strategies will be enhanced by broader policy initiatives currently underway to reform hospital reimbursement systems
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