418 research outputs found
Sulfur Deficiency of Sugar Beets
Sulfur deficiency of sugar beets (Beta Vulgaris L.) was first reported in
1941 by Tolman and Stoker (10) in beets grown for seed in the Willamette Valley
of Oregon. The symptoms were described as retarded growth, yellow color,
breakdown of leaf tissue, lack of flowering, and increased susceptibility to
disease. Since then sulfur deficiency of this crop has been reported in California
(11) and Sweden (5). Sulfur deficiency of sugar beets decreases seed
yield (10) as well as the yield and percent of sugar in the roots (5). A review
of the sulfur requirements of sugar, fiber and oil crops has been published (8)
N identical particles under quantum confinement: A many-body dimensional perturbation theory approach
Systems that involve N identical interacting particles under quantum
confinement appear throughout many areas of physics, including chemical,
condensed matter, and atomic physics. In this paper, we present the methods of
dimensional perturbation theory, a powerful set of tools that uses symmetry to
yield simple results for studying such many-body systems. We present a detailed
discussion of the dimensional continuation of the N-particle Schrodinger
equation, the spatial dimension D -> infinity equilibrium (D^0) structure, and
the normal-mode (D^{-1}) structure. We use the FG matrix method to derive
general, analytical expressions for the many-body normal-mode vibrational
frequencies, and we give specific analytical results for three confined N-body
quantum systems: the N-electron atom, N-electron quantum dot, and N-atom
inhomogeneous Bose-Einstein condensate with a repulsive hardcore potential
Dynamics of trapped bright solitons in the presence of localized inhomogeneities
We examine the dynamics of a bright solitary wave in the presence of a
repulsive or attractive localized ``impurity'' in Bose-Einstein condensates
(BECs). We study the generation and stability of a pair of steady states in the
vicinity of the impurity as the impurity strength is varied. These two new
steady states, one stable and one unstable, disappear through a saddle-node
bifurcation as the strength of the impurity is decreased. The dynamics of the
soliton is also examined in all the cases (including cases where the soliton is
offset from one of the relevant fixed points). The numerical results are
corroborated by theoretical calculations which are in very good agreement with
the numerical findings.Comment: 8 pages, 5 composite figures with low res (for high res pics please
go to http://www.rohan.sdsu.edu/~rcarrete/ [Publications] [Publication#41
Two-level system with a thermally fluctuating transfer matrix element: Application to the problem of DNA charge transfer
Charge transfer along the base-pair stack in DNA is modeled in terms of
thermally-assisted tunneling between adjacent base pairs. Central to our
approach is the notion that tunneling between fluctuating pairs is rate-limited
by the requirement of their optimal alignment. We focus on this aspect of the
process by modeling two adjacent base pairs in terms of a classical damped
oscillator subject to thermal fluctuations as described by a Fokker-Planck
equation. We find that the process is characterized by two time scales, a
result that is in accord with experimental findings.Comment: original file is revtex4, 10 pages, three eps figure
Low-temperature dynamical simulation of spin-boson systems
The dynamics of spin-boson systems at very low temperatures has been studied
using a real-time path-integral simulation technique which combines a
stochastic Monte Carlo sampling over the quantum fluctuations with an exact
treatment of the quasiclassical degrees of freedoms. To a large degree, this
special technique circumvents the dynamical sign problem and allows the
dynamics to be studied directly up to long real times in a numerically exact
manner. This method has been applied to two important problems: (1) crossover
from nonadiabatic to adiabatic behavior in electron transfer reactions, (2) the
zero-temperature dynamics in the antiferromagnetic Kondo region 1/2<K<1 where K
is Kondo's parameter.Comment: Phys. Rev. B (in press), 28 pages, 6 figure
A Coulomb gas approach to the anisotropic one-dimensional Kondo lattice model at arbitrary filling
We establish a mapping of a general spin-fermion system in one dimension into
a classical generalized Coulomb gas. This mapping allows a renormalization
group treatment of the anisotropic Kondo chain both at and away from
half-filling. We find that the phase diagram contains regions of paramagnetism,
partial and full ferromagnetic order. We also use the method to analyze the
phases of the Ising-Kondo chain.Comment: 19 pages, 9 figure
Bose-Einstein condensates in a one-dimensional double square well: Analytical solutions of the Nonlinear Schr\"odinger equation and tunneling splittings
We present a representative set of analytic stationary state solutions of the
Nonlinear Schr\"odinger equation for a symmetric double square well potential
for both attractive and repulsive nonlinearity. In addition to the usual
symmetry preserving even and odd states, nonlinearity introduces quite exotic
symmetry breaking solutions - among them are trains of solitons with different
number and sizes of density lumps in the two wells. We use the symmetry
breaking localized solutions to form macroscopic quantum superpositions states
and explore a simple model for the exponentially small tunneling splitting.Comment: 11 pages, 11 figures, revised version, typos and references correcte
Superfluid rotation sensor with helical laser trap
The macroscopic quantum states of the dilute bosonic ensemble in helical
laser trap at the temperatures about are considered in the
framework of the Gross-Pitaevskii equation. The helical interference pattern is
composed of the two counter propagating Laguerre-Gaussian optical vortices with
opposite orbital angular momenta and this pattern is driven in
rotation via angular Doppler effect. Macroscopic observables including linear
momentum and angular momentum of the atomic cloud are evaluated explicitly. It
is shown that rotation of reference frame is transformed into translational
motion of the twisted matter wave. The speed of translation equals the group
velocity of twisted wavetrain and alternates with a sign
of the frame angular velocity and helical pattern handedness .
We address detection of this effect using currently accessible laboratory
equipment with emphasis on the difference between quantum and classical fluids.Comment: 8 pages, 3 figures, accepted to publication Journ.Low Temp.Phy
Search for direct production of charginos and neutralinos in events with three leptons and missing transverse momentum in âs = 7 TeV pp collisions with the ATLAS detector
A search for the direct production of charginos and neutralinos in final states with three electrons or muons and missing transverse momentum is presented. The analysis is based on 4.7 fbâ1 of protonâproton collision data delivered by the Large Hadron Collider and recorded with the ATLAS detector. Observations are consistent with Standard Model expectations in three signal regions that are either depleted or enriched in Z-boson decays. Upper limits at 95% confidence level are set in R-parity conserving phenomenological minimal supersymmetric models and in simplified models, significantly extending previous results
Jet size dependence of single jet suppression in lead-lead collisions at sqrt(s(NN)) = 2.76 TeV with the ATLAS detector at the LHC
Measurements of inclusive jet suppression in heavy ion collisions at the LHC
provide direct sensitivity to the physics of jet quenching. In a sample of
lead-lead collisions at sqrt(s) = 2.76 TeV corresponding to an integrated
luminosity of approximately 7 inverse microbarns, ATLAS has measured jets with
a calorimeter over the pseudorapidity interval |eta| < 2.1 and over the
transverse momentum range 38 < pT < 210 GeV. Jets were reconstructed using the
anti-kt algorithm with values for the distance parameter that determines the
nominal jet radius of R = 0.2, 0.3, 0.4 and 0.5. The centrality dependence of
the jet yield is characterized by the jet "central-to-peripheral ratio," Rcp.
Jet production is found to be suppressed by approximately a factor of two in
the 10% most central collisions relative to peripheral collisions. Rcp varies
smoothly with centrality as characterized by the number of participating
nucleons. The observed suppression is only weakly dependent on jet radius and
transverse momentum. These results provide the first direct measurement of
inclusive jet suppression in heavy ion collisions and complement previous
measurements of dijet transverse energy imbalance at the LHC.Comment: 15 pages plus author list (30 pages total), 8 figures, 2 tables,
submitted to Physics Letters B. All figures including auxiliary figures are
available at
http://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/HION-2011-02
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