44,069 research outputs found
Fabric for micrometeoroid protection garment Patent
Structure of fabric layers for micrometeoroid protection garment with capability for eliminating heat shorts for use in manufacturing space suit
Improved heat-resistant garments
Fabrication method for protective clothing eliminates the common heat-short by avoiding the stitch which is common to all layers, and preventing external exposure of any stitch to the outer environment. A unique overlap arrangement is described and additional protective methods are discussed
Orbital stability in combined uniform axial and three-dimensional wiggler magnetic fields for free-electron lasers
Zachary Phys. Rev. A 29 (6), 3224 (1984) recently analyzed the instability of relativistic-electron helical trajectories in combined uniform axial and helical wiggler magnetic fields when the radial variation of the wiggler field is taken into account. It is shown here that the type 2 instability comprised of secular terms growing linearly in time, identified by Zachary and earlier by Diament Phys. Rev. A 23 (5), 2537 (1981), is an artifact of simple perturbation theory. A multiple-time-scale perturbation analysis reveals a nonsecular evolution on a slower time scale which accommodates an arbitrary initial perturbation. It is shown that, in the absence of exponential instability, the electron seeks a modified helical orbit more appropriate to its perturbed state and oscillates stably about it. Thus, the perturbed motion is oscillatory but nonsecular, and hence the helical orbits are stable
Changing clinical behaviour by making guidelines specific
Efforts to get doctors to follow guidelines have overlooked the importance of clear and concise recommendation
The effects of non-linear electron-phonon interactions on superconductivity and charge-density-wave correlations
Determinant quantum Monte Carlo (DQMC) simulations are used to study
non-linear electron-phonon interactions in a two-dimensional Holstein-like
model on a square lattice. We examine the impact of non-linear electron-lattice
interactions on superconductivity and on Peierls charge-density-wave (CDW)
correlations at finite temperatures and carrier concentrations. We find that
the CDW correlations are dramatically suppressed with the inclusion of even a
small non-linear interaction. Conversely, the effect of the non-linearity on
superconductivity is found to be less dramatic at high temperatures; however,
we find evidence that the non-linearity is ultimately detrimental to
superconductivity. These effects are attributed to the combined hardening of
the phonon frequency and a renormalization of the effective linear
electron-phonon coupling towards weaker values. These results demonstrate the
importance of non-linear interactions at finite carrier concentrations when one
is addressing CDW and superconducting order and have implications for
experiments that drive the lattice far from equilibrium.Comment: 5 Pages, 5 Figure
Origin of the transient unpulsed radio emission from the PSR B1259-63 binary system
We discuss the interpretation of transient, unpulsed radio emission detected
from the unique pulsar/Be-star binary system PSR B1259-63. Extensive monitoring
of the 1994 and 1997 periastron passages has shown that the source flares over
a 100-day interval around periastron, varying on time-scales as short as a day
and peaking at 60 mJy (~100 times the apastron flux density) at 1.4 GHz.
Interpreting the emission as synchrotron radiation, we show that (i) the
observed variations in flux density are too large to be caused by the shock
interaction between the pulsar wind and an isotropic, radiatively driven,
Be-star wind, and (ii) the radio emitting electrons do not originate from the
pulsar wind. We argue instead that the radio electrons originate from the
circumstellar disk of the Be star and are accelerated at two epochs, one before
and one after periastron, when the pulsar passes through the disk. A simple
model incorporating two epochs of impulsive acceleration followed by
synchrotron cooling reproduces the essential features of the radio light curve
and spectrum and is consistent with the system geometry inferred from pulsed
radio data.Comment: To be published in Astrophysical Journal Letters 7 pages, 1
postscript figur
Neutron interference scattering in crystalline solids Progress report
Neutron elastic and inelastic interference scattering cross section in crystalline lattices of solid
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