25,513 research outputs found
Wigner Crystallization in inhomogeneous one dimensional wires
We explore the theory of electrons confined by one dimensional power law
potentials. We calculate the density profile in the high density electron gas,
the low density Wigner crystal, and the intermediate regime. We extract the
momentum space wavefunction of the electron at the Fermi surface, which can be
measured in experiments on tunneling between parallel wires. The onset of
localization leads to a dramatic broadening of the momentum space wavefunction
together with pronounced sharpening (in energy) of the tunneling spectrum.Comment: 11 pages, 10 figures, RevTeX4: v2. Revised+Expande
Interference of Mycobacterium tuberculosis with macrophage responses
Tuberculosis, caused by Mycobacterium tuberculosis, has become an important health and economic burden, with more than four thousand people succumbing to the disease every day. Thus, there is an urgent need to understand the molecular basis of this pathogen's success in causing disease in humans, in order to develop new drugs superior to conventional drugs available at present. One reason why M. tuberculosis is such a dangerous microbe lies within its ability to survive within infected hosts, thereby efficiently circumventing host immune responses. Over the past few years, a number of mechanisms have been unravelled that are utilized by M. tuberculosis to survive within hosts and to avoid immune defence mechanisms. Several of these mechanisms have been described in this communication that may be useful for the development of novel compounds to treat tuberculosis
Collective oscillations of a Fermi gas near a Feshbach resonance
A sum rule approach is used to calculate the zero temperature oscillation
frequencies of a two component trapped atomic Fermi gas in the BCS-Bose
Einstein condensation crossover region. These sum rules are evaluated using a
local density approximation which explicitly includes Feshbach molecules.
Breathing modes show non-monotonic behavior as a function of the interaction
strength, while quadrupole modes are insensitive to interactions for both
spherically symmetric and axially symmetric traps. Quantitative agreement is
found with experiments on atomic system and with other theoretical
approaches.Comment: 7 pages, 4 figure
Wind-tunnel tests on a 3-dimensional fixed-geometry scramjet inlet at M = 2.30 to 4.60
Wind-tunnel tests were conducted on a baseline scramjet inlet model having fixed geometry and swept leading edges at M = 2.30, 2.96, 3.95, and 4.60 in the Langley unitary plan wind tunnel. The unit Reynolds number of the tests was held constant at 6.56 million per meter (2 million per foot). The objectives of the tests were to establish inlet performance and starting characteristics in the lower Mach number range of operation (less than M = 5). Surface pressures obtained on the inlet components are presented, along with the results of the internal flow surveys made at the throat and capture stations of the inlet. Contour plots of the inlet-flow-field parameters such as Mach numbers, pressure recovery, flow capture, local static and total pressure ratios at the survey stations are shown for the test Mach numbers
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