34,290 research outputs found
Development of mathematical models of environmental physiology
Selected articles concerned with mathematical or simulation models of human thermoregulation are presented. The articles presented include: (1) development and use of simulation models in medicine, (2) model of cardio-vascular adjustments during exercise, (3) effective temperature scale based on simple model of human physiological regulatory response, (4) behavioral approach to thermoregulatory set point during exercise, and (5) importance of skin temperature in sweat regulation
Lunar surface engineering properties experiment definition Quarterly report, 1 Oct. - 31 Dec. 1968
Mechanical properties of simulated lunar soil
An operational satellite scatterometer for wind vector measurements over the ocean
Performance requirements and design characteristics of a microwave scatterometer wind sensor for measuring surface winds over the oceans on a global basis are described. Scatterometer specifications are developed from user requirements of wind vector measurement range and accuracy, swath width, resolution cell size and measurement grid spacing. A detailed analysis is performed for a baseline fan-beam scatterometer design, and its performance capabilities for meeting the SeaSat-A user requirements. Various modes of operation are discussed which will allow the resolution of questions concerning the effects of sea state on the scatterometer wind sensing ability and to verify design boundaries of the instrument
Full Bulk Spin Polarization and Intrinsic Tunnel Barriers at the Surface of Layered Manganites
Transmission of information using the spin of the electron as well as its
charge requires a high degree of spin polarization at surfaces. At surfaces
however this degree of polarization can be quenched by competing interactions.
Using a combination of surface sensitive x-ray and tunneling probes, we show
for the quasi-two-dimensional bilayer manganites that the outermost Mn-O
bilayer, alone, is affected: it is a 1-nm thick insulator that exhibits no
long-range ferromagnetic order while the next bilayer displays the full spin
polarization of the bulk. Such an abrupt localization of the surface effects is
due to the two-dimensional nature of the layered manganite while the loss of
ferromagnetism is attributed to weakened double exchange in the reconstructed
surface bilayer and a resultant antiferromagnetic phase. The creation of a
well-defined surface insulator demonstrates the ability to naturally
self-assemble two of the most demanding components of an ideal magnetic tunnel
junction.Comment: 19 pages, 5 figure
Accurate Transfer Maps for Realistic Beamline Elements: Part I, Straight Elements
The behavior of orbits in charged-particle beam transport systems, including
both linear and circular accelerators as well as final focus sections and
spectrometers, can depend sensitively on nonlinear fringe-field and
high-order-multipole effects in the various beam-line elements. The inclusion
of these effects requires a detailed and realistic model of the interior and
fringe fields, including their high spatial derivatives. A collection of
surface fitting methods has been developed for extracting this information
accurately from 3-dimensional field data on a grid, as provided by various
3-dimensional finite-element field codes. Based on these realistic field
models, Lie or other methods may be used to compute accurate design orbits and
accurate transfer maps about these orbits. Part I of this work presents a
treatment of straight-axis magnetic elements, while Part II will treat bending
dipoles with large sagitta. An exactly-soluble but numerically challenging
model field is used to provide a rigorous collection of performance benchmarks.Comment: Accepted to PRST-AB. Changes: minor figure modifications, reference
added, typos corrected
Conditions for spin squeezing in a cold 87Rb ensemble
We study the conditions for generating spin squeezing via a quantum
non-demolition measurement in an ensemble of cold 87Rb atoms. By considering
the interaction of atoms in the 5S_{1/2}(F=1) ground state with probe light
tuned near the D2 transition, we show that, for large detunings, this system is
equivalent to a spin-1/2 system when suitable Zeeman substates and quantum
operators are used to define a pseudo-spin. The degree of squeezing is derived
for the rubidium system in the presence of scattering causing decoherence and
loss. We describe how the system can decohere and lose atoms, and predict as
much as 75% spin squeezing for atomic densities typical of optical dipole
traps.Comment: 9 pages, 3 figures, submitted to J. Opt. B: Quantum Semiclass. Opt.
Proceedings of ICSSUR'0
Constitutional and environmental factors related to serum lipid and lipoprotein levels
Serum lipoproteins and lipids in 657 human males correlated to multiple constitutional and environmental variable
Galactic Cosmic Ray Origins and OB Associations: Evidence from SuperTIGER Observations of Elements Fe through Zr
We report abundances of elements from Fe to Zr in the cosmic
radiation measured by the SuperTIGER (Trans-Iron Galactic Element Recorder)
instrument during 55 days of exposure on a long-duration balloon flight over
Antarctica. These observations resolve elemental abundances in this charge
range with single-element resolution and good statistics.
These results support a model of cosmic-ray origin in which the source
material consists of a mixture of 19\% material from massive stars
and 81\% normal interstellar medium (ISM) material with solar system
abundances. The results also show a preferential acceleration of refractory
elements (found in interstellar dust grains) by a factor of 4 over
volatile elements (found in interstellar gas) ordered by atomic mass (A). Both
the refractory and volatile elements show a mass-dependent enhancement with
similar slopes.Comment: 9 pages, 12 figures, 2 tables, accepted by Ap
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