12,203 research outputs found
Foldable beam
A foldable beam possessing superior qualities of light weight, compactness for transportation, quick deployment with minimum use of force, and high strength is described. These qualities are achieved through the use of a series of longitudinally rigid segments, hinged along one side and threaded by one or two cables along the opposite side. Tightening the cables holds the beam extended. Loosening the cables permits the segments to fold away from the threaded side. In one embodiment the segments are connected by canted hinges with the result that the beam may be folded in a helix-like configuration around a cylinder. In another embodiment the segments themselves may be hinged to fold flat laterally as the beam is folded, resulting in a configuration that may be helixed around a shorter cylinder
Relativistic semiclassical approach in strong-field nonlinear photoionization
Nonlinear relativistic ionization phenomena induced by a strong laser
radiation with elliptically polarization are considered. The starting point is
the classical relativistic action for a free electron moving in the
electromagnetic field created by a strong laser beam. The application of the
relativistic action to the classical barrier-suppression ionization is briefly
discussed. Further the relativistic version of the Landau-Dykhne formula is
employed to consider the semiclassical sub-barrier ionization. Simple
analytical expressions have been found for: (i) the rates of the strong-field
nonlinear ionization including relativistic initial and final state effects;
(ii) the most probable value of the components of the photoelectron final state
momentum; (iii) the most probable direction of photoelectron emission and (iv)
the distribution of the photoelectron momentum near its maximum value.Comment: 13 pages, 3 figures, to be published in Phys. Rev.
Heat sterilizable and impact resistant Ni-Cd battery development Quarterly report, 1 Apr. - 30 Jun. 1969
Electrochemistry, battery engineering, and impact tests of heat sterilizable nickel cadmium cell
A Search for Single Radio Pulses and Bursts from Southern AXPs
We observed four southern AXPs in 1999 near 1400 MHz with the Parkes 64-m
radio telescope to search for periodic radio emission. No Fourier candidates
were discovered in the initial analysis, but the recent radio activity observed
for the AXP XTE J1810-197 has prompted us to revisit these data to search for
single radio pulses and bursts. The data were searched for both persistent and
bursting radio emission at a wide range of dispersion measures, but no
detections of either kind were made. These results further weaken the proposed
link between rotating radio transient sources and magnetars. However, continued
radio searches of these and other AXPs at different epochs are warranted given
the transient nature of the radio emission seen from XTE J1810-197, which until
very recently was the only known radio-emitting AXP.Comment: 3 pages, including 1 table. To appear in the proceedings of "40 Years
of Pulsars: Millisecond Pulsars, Magnetars, and More", August 12-17, 2007,
McGill University, Montreal, Canad
CAP1 expression is developmentally regulated in Xenopus
We have cloned and characterized a Xenopus member of the cyclase associated protein (CAP) gene family. xCAP1 is expressed as a maternal transcript, but is up-regulated prior to gastrulation and subsequently localizes to head mesenchyme, lens, otic vesicle, and trunk mesoderm including the pronephros. At different stages, the gone also appears to differentiate surface from deep (sensorial) ectoderm. As in Drosophila, Xenopus CAP1 is expressed in the developing eye, specifically in the differentiating lens. However, in distinction to Drosophila, Xenopus CAP1 does not express in periodically arrayed neural bands. (C) 2002 Elsevier Science Ireland Ltd. All rights reserved
Dzyaloshinsky-Moriya Spin Canting in the LTT Phase of La2-x-yEuySrxCuO4
The Cu spin magnetism in La2-x-yEuySrxCuO4 (x<=0.17; y<=0.2) has been studied
by means of magnetization measurements up to 14 T. Our results clearly show
that in the antiferromagnetic phase Dzyaloshinsky-Moriya (DM)superexchange
causes Cu spin canting not only in the LTO phase but also in the LTLO and LTT
phases. In La1.8Eu0.2CuO4 the canted DM-moment is about 50% larger than in pure
La2CuO4 which we attribute to the larger octahedral tilt angle. We also find
clear evidence that the size of the DM-moment does not change significantly at
the structural transition at T_LT from LTO to LTLO and LTT. The most important
change induced by the transition is a significant reduction of the magnetic
coupling between the CuO2 planes. As a consequence, the spin-flip transition of
the canted Cu spins which is observed in the LTO phase for magnetic field
perpendicular to the CuO2 planes disappears in the LTT phase. The shape of the
magnetization curves changes from the well known spin-flip type to a
weak-ferromagnet type. However, no spontaneous weak ferromagnetism is observed
even at very low temperatures, which seems to indicate that the interlayer
decoupling in our samples is not perfect. Nonetheless, a small fraction (<15%)
of the DM-moments can be remanently magnetized throughout the entire
antiferromagnetically ordered LTT/LTLO phase, i.e. for T<T_LT and x<0.02. It
appears that the remanent DM-moment is perpendicular to the CuO2 planes. For
magnetic field parallel to the CuO2 planes we find that the critical field of
the spin-flop transition decreases in the LTLO phase, which might indicate a
competition between different in-plane anisotropies. To study the Cu spin
magnetism in La2-x-yEuySrxCuO4, a careful analysis of the Van Vleck
paramagnetism of the Eu3+ ions was performed.Comment: 22 pages, 27 figure
PAM14: TREATMENT WITH LEFLUNOMIDE IMPROVES THE UTILITY OF PATIENTS WITH ACTIVE RHEUMATOID ARTHRITIS: AN APPLICATION OF THE SF-6D
Relativistic photoelectron spectra in the ionization of atoms by elliptically polarized light
Relativistic tunnel ionization of atoms by intense, elliptically polarized
light is considered. The relativistic version of the Landau-Dykhne formula is
employed. The general analytical expression is obtained for the relativistic
photoelectron spectra. The most probable angle of electron emission, the
angular distribution near this angle, the position of the maximum and the width
of the energy spectrum are calculated. In the weak field limit we obtain the
familiar non-relativistic results. For the case of circular polarization our
analytical results are in agreement with recent derivations of Krainov [V.P.
Krainov, J. Phys. B, {\bf 32}, 1607 (1999)].Comment: 8 pages, 2 figures, accepted for publication in Journal of Physics
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