865 research outputs found
Vortex phase transformations probed by the local ac response of Bi_{2}Sr_{2}CaCu_{2}O_{8+\delta} single crystals with various doping
The linear ac response of the vortex system is measured locally in Bi-2212
single crystals at various doping, using a miniature two-coil mutual-inductance
technique. It was found that a step-like change in the local ac response takes
place exactly at the first-order transition (FOT) temperature T_{FOT}(H)
determined by a global dc magnetization measurement. The T_{FOT}(H) line in the
H-T phase diagram becomes steeper with increasing doping. In the higher-field
region where the FOT is not observed, the local ac response still shows a
broadened but distinct feature, which can be interpreted to mark the growth of
a short-range order in the vortex system.Comment: 4 pages, including 5 eps figure
In Vitro Toxicity And Control Of Meloidogyne Incognita In Soybean By Rosemary Extract
The control of nematodes in plants can be challenging, and there is a need for alternative, environmentally conscious methods for their management. The purpose of this study was to evaluate the effect of rosemary extract (Rosmarinus officinalis) on the in vitro toxicity and control of Meloidogyne incognita in CD 206 and CD 215 soybean cultivars. Using an in vitro assay, 500 M. incognita eggs per plate were observed for 15 days after incubation with rosemary extract at concentrations of 1%, 5%, and 10%. Soybean plants were studied under greenhouse conditions, and starting at V3 stage, were sprayed weekly with the same concentration of rosemary extract for 64 days. Three days after the first treatment, each soybean plant was inoculated with 1800 eggs and 400 second-stage juveniles (J2). At the end of this essay, number of eggs and J2 in the roots and soil, number of galls, and the reproduction factor (RF) were evaluated. Our results showed that in the in vitro assay, rosemary extract reduced the number of M. incognita eggs that hatched. Under greenhouse conditions, the CD 206 cultivar showed a 46.5% reduction in the number of galls, as well as fewer eggs in the soil and a lower RF. Similarly, in the CD 215 cultivar, the number of eggs was reduced and the RF was lower. These results indicate the potential for rosemary extract to control M. incognita in soybean crops.37110311
Non-Traditional University Research Partners That Facilitate Service Learning and Graduate Research for Sustainable Development
Hydrodynamic modes of a 1D trapped Bose gas
We consider two regimes where a trapped Bose gas behaves as a one-dimensional
system. In the first one the Bose gas is microscopically described by 3D mean
field theory, but the trap is so elongated that it behaves as a 1D gas with
respect to low frequency collective modes. In the second regime we assume that
the 1D gas is truly 1D and that it is properly described by the Lieb-Liniger
model. In both regimes we find the frequency of the lowest compressional mode
by solving the hydrodynamic equations. This is done by making use of a method
which allows to find analytical or quasi-analytical solutions of these
equations for a large class of models approaching very closely the actual
equation of state of the Bose gas. We find an excellent agreement with the
recent results of Menotti and Stringari obtained from a sum rule approach.Comment: 15 pages, revtex, 1 figure
Revisiting consistency conditions for quantum states of systems on closed timelike curves: an epistemic perspective
There has been considerable recent interest in the consequences of closed
timelike curves (CTCs) for the dynamics of quantum mechanical systems. A vast
majority of research into this area makes use of the dynamical equations
developed by Deutsch, which were developed from a consistency condition that
assumes that mixed quantum states uniquely describe the physical state of a
system. We criticise this choice of consistency condition from an epistemic
perspective, i.e., a perspective in which the quantum state represents a state
of knowledge about a system. We demonstrate that directly applying Deutsch's
condition when mixed states are treated as representing an observer's knowledge
of a system can conceal time travel paradoxes from the observer, rather than
resolving them. To shed further light on the appropriate dynamics for quantum
systems traversing CTCs, we make use of a toy epistemic theory with a strictly
classical ontology due to Spekkens and show that, in contrast to the results of
Deutsch, many of the traditional paradoxical effects of time travel are
present.Comment: 10 pages, 6 figures, comments welcome; v2 added references and
clarified some points; v3 published versio
Simulation study of Non-ergodicity Transitions: Gelation in Colloidal Systems with Short Range Attractions
Computer simulations were used to study the gel transition occurring in
colloidal systems with short range attractions. A colloid-polymer mixture was
modelled and the results were compared with mode coupling theory expectations
and with the results for other systems (hard spheres and Lennard Jones). The
self-intermediate scattering function and the mean squared displacement were
used as the main dynamical quantities. Two different colloid packing fractions
have been studied. For the lower packing fraction, -scaling holds and
the wave-vector analysis of the correlation function shows that gelation is a
regular non-ergodicity transition within MCT. The leading mechanism for this
novel non-ergodicity transition is identified as bond formation caused by the
short range attraction. The time scale and diffusion coefficient also show
qualitatively the expected behaviour, although different exponents are found
for the power-law divergences of these two quantities. The non-Gaussian
parameter was also studied and very large correction to Gaussian behaviour
found. The system with higher colloid packing fraction shows indications of a
nearby high-order singularity, causing -scaling to fail, but the
general expectations for non-ergodicity transitions still hold.Comment: 13 pages, 15 figure
Plasmonic atoms and plasmonic molecules
The proposed paradigm of plasmonic atoms and plasmonic molecules allows one
to describe and predict the strongly localized plasmonic oscillations in the
clusters of nanoparticles and some other nanostructures in uniform way.
Strongly localized plasmonic molecules near the contacting surfaces might
become the fundamental elements (by analogy with Lego bricks) for a
construction of fully integrated opto-electronic nanodevices of any complexity
and scale of integration.Comment: 30 pages, 16 figure
Potential and current distribution in strongly anisotropic Bi(2)Sr(2) CaCu(2)O(8) single crystals at current breakdown
Experiments on potential differences in the low-temperature vortex solid
phase of monocrystalline platelets of superconducting Bi(2)Sr(2)CaCu(2)O(8)
(BSCCO) subjected to currents driven either through an "ab" surface or from one
such surface to another show evidence of a resistive/nonresistive front moving
progressively out from the current contacts as the current increases. The depth
of the resistive region has been measured by a novel in-depth voltage probe
contact. The position of the front associated with an injection point appears
to depend only on the current magnitude and not on its withdrawal point. It is
argued that enhanced nonresistive superconducting anisotropy limits current
penetration to less than the London length and results in a flat rectangular
resistive region with simultaneous "ab" and "c" current breakdown which moves
progressively out from the injection point with increasing current.
Measurements in "ab" or "c" configurations are seen to give the same
information, involving both ab-plane and c-axis conduction properties.Comment: 9 pages, 13 figures, typo error corrected, last section was refine
The Tachyon Potential in the Sliver Frame
We evaluate the tachyon potential in the Schnabl gauge through off-shell
computations in the sliver frame. As an application of the results of our
computations, we provide a strong evidence that Schnabl's analytic solution for
tachyon condensation in open string field theory represents a saddle point
configuration of the full tachyon potential. Additionally we verify that
Schnabl's analytic solution lies on the minimum of the effective tachyon
potential.Comment: v1: 19 pages, 1 figure, 1 table; v2: 20 pages, 1 figure, 2 tables, 1
reference added, comments added; v3: 21 pages, 1 figure, 2 tables, 4
references added, comments adde
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