1,680 research outputs found
Establishment of an arabinose-inducible system in Stenotrophomonas maltophilia
A pBBad22T-derived conditioned arabinose (Ara)-inducible expression system was evaluated in Stenotrophomonas maltophilia (an opportunistic pathogen and has gained increasing attention as a cause of healthcare-associated infection). S. maltophilia cannot grow well when Ara is the sole available carbon source. The induction kinetic study, optimal inducer concentration determination, and depletion experiment were performed by using a xylE gene fusion construct, pBxylE, to monitor the expression of pBBad22T in S. maltophilia. For induction survey, the expression of catechol 2,3-dioxygenase (C23O), encoded by xylE gene, continuously increases during an 8-h induced course and can be modulated by different inducer concentrations. The applied induction condition of pBBad22T in S. maltophilia is the inducer concentration ranging from 0.1% to 0.5% for an induction time of 4 h. For repression evaluation, the C23O expression is rapidly turned off within 30 min after the removal of Ara. Accordingly, the established Ara-inducible system can provide a convenient tool for the study of S. maltophilia
Induced four fold anisotropy and bias in compensated NiFe/FeMn double layers
A vector spin model is used to show how frustrations within a multisublattice
antiferromagnet such as FeMn can lead to four-fold magnetic anisotropies acting
on an exchange coupled ferromagnetic film. Possibilities for the existence of
exchange bias are examined and shown to exist for the case of weak chemical
disorder at the interface in an otherwise perfect structure. A sensitive
dependence on interlayer exchange is found for anisotropies acting on the
ferromagnet through the exchange coupling, and we show that a wide range of
anisotropies can appear even for a perfect crystalline structure with an
ideally flat interface.Comment: 7 pages, 7 figure
Experimentally realizable characterizations of continuous variable Gaussian states
Measures of entanglement, fidelity and purity are basic yardsticks in quantum
information processing. We propose how to implement these measures using linear
devices and homodyne detectors for continuous variable Gaussian states. In
particular, the test of entanglement becomes simple with some prior knowledge
which is relevant to current experiments.Comment: 4 pages, This paper supersedes quant-ph/020315
Field dynamics and kink-antikink production in rapidly expanding systems
Field dynamics in a rapidly expanding system is investigated by transforming
from space-time to the rapidity - proper-time frame. The proper-time dependence
of different contributions to the total energy is established. For systems
characterized by a finite momentum cut-off, a freeze-out time can be defined
after which the field propagation in rapidity space ends and the system decays
into decoupled solitons, antisolitons and local vacuum fluctuations. Numerical
simulations of field evolutions on a lattice for the (1+1)-dimensional
model illustrate the general results and show that the freeze-out time and
average multiplicities of kinks (plus antikinks) produced in this 'phase
transition' can be obtained from simple averages over the initial ensemble of
field configurations. An extension to explicitly include additional dissipation
is discussed. The validity of an adiabatic approximation for the case of an
overdamped system is investigated. The (3+1)-dimensional generalization may
serve as model for baryon-antibaryon production after heavy-ion collisions.Comment: 18 pages, 7 figures. Two references added. New subsection III.E
added. Final version accepted for publication in PR
Emerging threat of thrips-borne Melon yellow spot virus on melon and watermelon in Taiwan
The thrips-borne Melon yellow spot virus (MYSV) has recently been found infecting cucurbits in Taiwan. However, this virus was indistinguishable from another thrips-borne virus species Watermelon silver mottle virus (WSMoV), which has been devastating on cucurbits in Taiwan for decades, when the antisera against their nucleocapsid proteins (NPs) were used for diagnosis. To understand the incidences of WSMoV and MYSV in melon and watermelon fields, a survey was conducted in central and southern Taiwan from July 2007 to December 2009. The samples collected from symptomatic plants were tested by indirect enzyme-linked immunosorbent assay (ELISA) using monoclonal antibodies (MAbs) specific to the NP of WSMoV or MYSV and the reliability of the results was verified by reverse transcription-polymerase chain reaction (RT-PCR) using species-specific primers. Among a total of 10,480 melon samples collected, 6% and 18.2% of them were found singly infected with WSMoV and MYSV, respectively, and 0.16% infected with both viruses. On the other hand, among 1,811 watermelon samples assayed, 22.4% and 9.2% samples were singly infected with WSMoV and MYSV, respectively, and 0.17% were infected with both viruses. In addition, the aphid-borne viruses Zucchini yellow mosaic virus (ZYMV), Papaya ringspot virus watermelon type (PRSV-W) and Cucumber mosaic virus (CMV) were also detected as prevalent viruses. Our results indicated that mixed infection with the two thrips-borne viruses is rare. Moreover, host preference for both viruses is different; WSMoV prevails on watermelon whereas MYSV is more widespread on melon. We conclude that MYSV has become a serious threat for watermelon and melon production in Taiwan and the possible control measures are discussed
Dynamical approach to spectator fragmentation in Au+Au reactions at 35 MeV/A
The characteristics of fragment emission in peripheral Au+Au
collisions 35 MeV/A are studied using the two clusterization approaches within
framework of \emph{quantum molecular dynamics} model. Our model calculations
using \emph{minimum spanning tree} (MST) algorithm and advanced clusterization
method namely \emph{simulated annealing clusterization algorithm} (SACA) showed
that fragment structure can be realized at an earlier time when spectators
contribute significantly toward the fragment production even at such a low
incident energy. Comparison of model predictions with experimental data reveals
that SACA method can nicely reproduce the fragment charge yields and mean
charge of the heaviest fragment. This reflects suitability of SACA method over
conventional clusterization techniques to investigate spectator matter
fragmentation in low energy domain.Comment: 6 pages, 5 figures, accepte
Covariant derivative expansion of fermionic effective action at high temperatures
We derive the fermionic contribution to the 1-loop effective action for A_4
and A_i fields at high temperatures, assuming that gluon fields are slowly
varying but allowing for an arbitrary amplitude of A_4.Comment: RevTex 4, 11 pages, 3 figures. Version 2: Typos corrected; magnetic
fields restricted to parallel sector. Version accepted for publication in PR
Covariant derivative expansion of Yang-Mills effective action at high temperatures
Integrating out fast varying quantum fluctuations about Yang--Mills fields
A_i and A_4, we arrive at the effective action for those fields at high
temperatures. Assuming that the fields A_i and A_4 are slowly varying but that
the amplitude of A_4 is arbitrary, we find a non-trivial effective gauge
invariant action both in the electric and magnetic sectors. Our results can be
used for studying correlation functions at high temperatures beyond the
dimensional reduction approximation, as well as for estimating quantum weights
of classical static configurations such as dyons.Comment: Minor changes. References added. Paper accepted for publication in
Phys.Rev.
Continuous variable entanglement and quantum state teleportation between optical and macroscopic vibrational modes through radiation pressure
We study an isolated, perfectly reflecting, mirror illuminated by an intense
laser pulse. We show that the resulting radiation pressure efficiently
entangles a mirror vibrational mode with the two reflected optical sideband
modes of the incident carrier beam. The entanglement of the resulting
three-mode state is studied in detail and it is shown to be robust against the
mirror mode temperature. We then show how this continuous variable entanglement
can be profitably used to teleport an unknown quantum state of an optical mode
onto the vibrational mode of the mirror.Comment: 18 pages, 10 figure
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