928 research outputs found
A Note on Chiral Symmetry Breaking from Intersecting Branes
In this paper, we will consider the chiral symmetry breaking in the
holographic model constructed from the intersecting brane configuration, and
investigate the Nambu-Goldstone bosons associated with this symmetry breaking.Comment: 16 pp, minor changes, to appear PR
Geographical, meteorological and vectorial factors related to malaria re-emergence in Huang-Huai River of central China
<p/> <p>Background</p> <p>Malaria still represents a significant public health problem in China, and the cases dramatically increased in the areas along the Huang-Huai River of central China after 2001. Considering spatial aggregation of malaria cases and specific vectors, the geographical, meteorological and vectorial factors were analysed to determine the key factors related to malaria re-emergence in these particular areas.</p> <p>Methods</p> <p>The geographic information of 357 malaria cases and 603 water bodies in 113 villages were collected to analyse the relationship between the residence of malaria cases and water body. Spearman rank correlation, multiple regression, curve fitting and trend analysis were used to explain the relationship between the meteorological factors and malaria incidence. Entomological investigation was conducted in two sites to get the vectorial capacity and the basic reproductive rate to determine whether the effect of vector lead to malaria re-emergence.</p> <p>Results</p> <p>The distances from household of cases to the nearest water-body was positive-skew distributed, the median was 60.9 m and 74% malaria cases were inhabited in the extent of 60 m near the water body, and the risk rate of people live there attacked by malaria was higher than others(<it>OR </it>= 1.6, 95%<it>CI </it>(1.042, 2.463), <it>P </it>< 0.05). The annual average temperature and rainfall may have close relationship with annual incidence. The average monthly temperature and rainfall were the key factors, and the correlation coefficients are 0.501 and 0.304(<it>P </it>< 0.01), respectively. Moreover, 75.3% changes of monthly malaria incidence contributed to the average monthly temperature (T<sub>mean</sub>), the average temperature of last two months(T<sub>mean01</sub>) and the average rainfall of current month (R<sub>mean</sub>) and the regression equation was Y = -2.085 + 0.839I<sub>1 </sub>+ 0.998T<sub>mean0 </sub>- 0.86T<sub>mean01 </sub>+ 0.16R<sub>mean0</sub>. All the collected mosquitoes were <it>Anopheles sinensis</it>. The vectorial capacity and the basic reproductive rate of <it>An. sinensis </it>in two sites were 0.6969, 0.4983 and 2.1604, 1.5447, respectively.</p> <p>Conclusion</p> <p>The spatial distribution between malaria cases and water-body, the changing of meteorological factors, and increasing vectorial capacity and basic reproductive rate of <it>An. sinensis </it>leaded to malaria re-emergence in these areas.</p
Internal friction and Jahn-Teller effect in the charge-ordered La1-xCaxMnO3 (0.5<x<0.87)
The Jahn-Teller effect in the charge-ordered (CO) state for La1-xCaxMnO3
(0.5<x<0.87) was studied by measuring the low-temperature powder x-ray
diffraction, internal friction, and shear modulus. We find that the
electron-lattice interaction with the static Jahn-Teller distortion is the
strongest near x=0.75 in the CO state. It was particularly observed that a
crossover of the Jahn-Teller vibration mode from Q2 to Q3 near x=0.75 induces
crossovers of the crystal structure from tetragonally compressed to
tetragonally elongated orthorhombic, and of the magnetic structure from CE-type
to C-type near x=0.75. The experimental results give strong evidence that the
Jahn-Teller effect not only plays a key role in stabilizing the CO state, but
also determines the magnetic and crystal structures in the CO state for
La1-xCaxMnO3.Comment: 13 pages, 3 figures, PD
Weakly Nonlinear AC Response: Theory and Application
We report a microscopic and general theoretical formalism for electrical
response which is appropriate for both DC and AC weakly nonlinear quantum
transport. The formalism emphasizes the electron-electron interaction and
maintains current conservation and gauge invariance. It makes a formal
connection between linear response and scattering matrix theory at the weakly
nonlinear level. We derive the dynamic conductance and predict the
nonlinear-nonequilibrium charge distribution. The definition of a nonlinear
capacitance leads to a remarkable scaling relation which can be measured to
give microscopic information about a conductor
Evolution of entanglement for quantum mixed states
A simple relation is introduced for concurrence to describe how much the
entanglement of bipartite system is at least left if either (or both) subsystem
undergoes an arbitrary physical process. This provides a lower bound for
concurrence of mixed states (pure states are included) in contrast to the upper
bound given by Konrad et al [Nature Physics \textbf{4}, 99 (2008)]. Our results
are also suitable for a general high dimensional bipartite quantum systems.Comment: 6 pages and 1 figur
Scattering Matrix Theory For Nonlinear Transport
We report a scattering matrix theory for dynamic and nonlinear transport in
coherent mesoscopic conductors. In general this theory allows predictions of
low frequency linear dynamic conductance, as well as weakly nonlinear DC
conductance. It satisfies the conditions of gauge invariance and electric
current conservation, and can be put into a form suitable for numerical
computation. Using this theory we examine the third order weakly nonlinear DC
conductance of a tunneling diode
Phase Behavior of Columnar DNA Assemblies
The pair interaction between two stiff parallel linear DNA molecules depends
not only on the distance between their axes but on their azimuthal orientation.
The positional and orientational order in columnar B-DNA assemblies in solution
is investigated, based on the DNA-DNA electrostatic pair potential that takes
into account DNA helical symmetry and the amount and distribution of adsorbed
counterions. A phase diagram obtained by lattice sum calculations predicts a
variety of positionally and azimuthally ordered phases and bundling transitions
strongly depending on the counterion adsorption patterns.Comment: 4 pages, 3 figures, submitted to PR
Intermittent QPO properties of MAXI J1820+070 revealed by Insight-HXMT
We investigate the dynamical properties of low frequency quasi-periodic
oscillations (QPOs) observed from the black hole X-ray binary MAXI J1820+070
during the early part of its 2018 outburst, when the system was in a bright
hard state. To this aim, we use a series of observations from the Hard X-ray
Modulation Telescope Insight-HXMT, and apply a wavelet decomposition (weighted
wavelet Z-transforms) to the X-ray light-curve. We find that the QPO phenomenon
is intermittent within each individual observation, with some sub-intervals
where the oscillation is strongly detected (high root-mean-square amplitude)
and others where it is weak or absent. The average life time of individual QPO
segments is ~ 5 oscillation cycles, with a 3 sigma tail up to ~ 20 cycles.
There is no substantial difference between the energy spectra during intervals
with strong and weak/absent QPOs. We discuss two possible reasons for the
intermittent QPO strength, within the precessing jet model previously proposed
for MAXI J1820+070. In the rigid precession model, intermittent QPOs are
predicted to occur with a coherence Q ~ a few when the disk alignment
time-scale is only a few times the precession time-scale. Alternatively, we
suggest that changes in oscillation amplitude can be caused by changes in the
jet speed. We discuss a possible reason for the intermittent QPO strength,
within the precessing jet model previously proposed for MAXI J1820+070: we
suggest that changes in oscillation amplitude are caused by changes in the jet
speed. We argue that a misaligned, precessing jet scenario is also consistent
with other recent observational findings that suggest an oscillation of the
Compton reflection component in phase with the QPOs.Comment: 8 pages, 4 figure
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