12,535 research outputs found
Simulation of electron transport in quantum well devices
Double barrier resonant tunneling diodes (DBRTD) have received much attention as possible terahertz devices. Despite impressive experimental results, the specifics of the device physics (i.e., how the electrons propagate through the structure) are only qualitatively understood. Therefore, better transport models are warranted if this technology is to mature. In this paper, the Lattice Wigner function is used to explain the important transport issues associated with DBRTD device behavior
Meissner screening mass in two-flavor quark matter at nonzero temperature
We calculate the Meissner screening mass of gluons 4--7 in two-flavor quark
matter at nonzero temperature. To this end, we study the effective potential of
the 2SC/g2SC phases including a vector condensate . We find
that the Meissner mass becomes real at the critical temperature which is about
the half of the chemical potential mismatch. The phase diagram of the neutral
two-flavor color superconductor is presented in the plane of temperature and
coupling strength. We indicate the unstable region for gluons 4--7 on the phase
diagram.Comment: 4 pages, 3 figures, minor revisions to text, version to appear in PR
Experimental Evidence of Time Delay Induced Death in Coupled Limit Cycle Oscillators
Experimental observations of time delay induced amplitude death in a pair of
coupled nonlinear electronic circuits that are individually capable of
exhibiting limit cycle oscillations are described. In particular, the existence
of multiply connected death islands in the parameter space of the coupling
strength and the time delay parameter for coupled identical oscillators is
established. The existence of such regions was predicted earlier on theoretical
grounds in [Phys. Rev. Lett. 80, 5109 (1998); Physica 129D, 15 (1999)]. The
experiments also reveal the occurrence of multiple frequency states, frequency
suppression of oscillations with increased time delay and the onset of both
in-phase and anti-phase collective oscillations.Comment: 4 aps formatted RevTeX pages; 6 figures; to appear in Phys. Rev. Let
Collective excitations, instabilities, and ground state in dense quark matter
We study the spectrum of light plasmons in the (gapped and gapless)
two-flavor color superconducting phases and its connection with the
chromomagnetic instabilities and the structure of the ground state. It is
revealed that the chromomagnetic instabilities in the 4-7th and 8th gluonic
channels correspond to two very different plasmon spectra. These spectra lead
us to the unequivocal conclusion about the existence of gluonic condensates
(some of which can be spatially inhomogeneous) in the ground state. We also
argue that spatially inhomogeneous gluonic condensates should exist in the
three-flavor quark matter with the values of the mass of strange quark
corresponding to the gapless color-flavor locked state.Comment: Revtex, 5 pages, 4 figures, two figures and clarifications added, to
appear in PRD (Rapid Communications
Recent Developments In Serology And Electron Microscopy For The Diagnosis Of Plant Virus Diseases
One ol the important prerequisites to
the management of virus diseases is the
precise identification o f the C~USa~geIn t.
Diagnosis of viral diseases n3w demands
a wide variety of skills which are constantly
being improved as a result of rapid
technological advances. By the introduction
o f increasinglv sensitive serological
methods and transmission electron rnicro-
*copy, i t is now pomible to detect viruses
that are present in plant tissues in extremely
low concentrations. Many early reports on
the occurrence of viral diseases have been
largely based on visual symptoms and
host range. External symptoms of diseases
associated with spiroplasma, rickertsiae,
mvcoplesma-like organisms and even
nutrient deficiency symptoms have been
confused with viral diseases. In addition.
external symptoms produced by viruses
can b4 greatlv influenced bv such factors
ss genotype, plant age, environment and
strain of virus present
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