4,070 research outputs found
Neurophysiology
Contains reports on sixo research projects.National Institutes of Health (Grant 5 RO1 NB-04985-03)National Institutes of Health (Grant 5 RO1 NB-4897-03)National Institutes of Health (Grant NB-06251-01)U.S. Air Force (Office of Scientific Research) under Grant AF-AFOSR-880-65U.S. Air Force (Research and Technology Division) under Contract AF33(615)-1747The Teagle Foundation, Inc. (Grant)Bell Telephone Laboratories, Inc. (Grant)Instrumentation Laboratory under the auspices of DSR Project 55-257Bioscience Division of National Aeronautics and Space Administratio
Anomalous spin-splitting of two-dimensional electrons in an AlAs Quantum Well
We measure the effective Lande g-factor of high-mobility two-dimensional
electrons in a modulation-doped AlAs quantum well by tilting the sample in a
magnetic field and monitoring the evolution of the magnetoresistance
oscillations. The data reveal that |g| = 9.0, which is much enhanced with
respect to the reported bulk value of 1.9. Surprisingly, in a large range of
magnetic field and Landau level fillings, the value of the enhanced g-factor
appears to be constant.Comment: 4 pages, 3 figure
Mesoscopic Capacitors: A Statistical Analysis
The capacitance of mesoscopic samples depends on their geometry and physical
properties, described in terms of characteristic times scales. The resulting ac
admittance shows sample to sample fluctuations. Their distribution is studied
here -through a random-matrix model- for a chaotic cavity capacitively coupled
to a backgate: it is observed from the distribution of scattering time delays
for the cavity, which is found analytically for the orthogonal, unitary, and
symplectic universality classes, one mode in the lead connecting the cavity to
the reservoir and no direct scattering. The results agree with numerical
simulations.Comment: 4 pages (Revtex), 4 PS figures. Minor corrections. New e-mail
address: [email protected] [email protected] e-mail
address: [email protected]
Recommended from our members
FLOWTRAN-TF v1.2 source code
The FLOWTRAN-TF code development effort was initiated in early 1989 as a code to monitor production reactor cooling systems at the Savannah River Plant. This report is a documentation of the various codes that make up FLOWTRAN-TF
Comparison of the Electronic Structures and Energetics of Ferroelectric LiNbO3 and LiTaO3
This paper explains the origin of the ferroelectric instability in LiNbO3 and
LiTaO3 and compares the electronic structures and energetics of the two
materials.Comment: 31 pages, 11 Postscript figure
Apparent Metallic Behavior at B = 0 of a two-dimensional electron system in AlAs
We report the observation of metallic-like behavior at low temperatures and
zero magnetic field in two dimensional (2D) electrons in an AlAs quantum well.
At high densities the resistance of the sample decreases with decreasing
temperature, but as the density is reduced the behavior changes to insulating,
with the resistance increasing as the temperature is decreased. The effect is
similar to that observed in 2D electrons in Si-MOSFETs, and in 2D holes in SiGe
and GaAs, and points to the generality of this phenomenon
A Cryogenic Underground Observatory for Rare Events: Cuore, an Update
CUORE is a proposed tightly packed array of 1000 TeO_{2} bolometers, each
being a cube 5 cm on a side with a mass of 750 gms. The array consists of 25
vertical towers, arranged in a square, of 5 towers by 5 towers, each containing
10 layers of 4 crystals. The design of the detector is optimized for ultralow-
background searches for neutrinoless double beta decay of ^{130}Te (33.8%
abundance), cold dark matter, solar axions, and rare nuclear decays. A
preliminary experiment involving 20 crystals of various sizes (MIBETA) has been
completed, and a single CUORE tower is being constructed as a smaller scale
experiment called CUORICINO. The expected performance and sensitivity, based on
Monte Carlo simulations and extrapolations of present results, are reported.Comment: in press: Nucl. Phys. of Russian Academy of Sc
Six-dimensional Supergravity and Projective Superfields
We propose a superspace formulation of N=(1,0) conformal supergravity in six
dimensions. The corresponding superspace constraints are invariant under
super-Weyl transformations generated by a real scalar parameter. The known
variant Weyl super-multiplet is recovered by coupling the geometry to a
super-3-form tensor multiplet. Isotwistor variables are introduced and used to
define projective superfields. We formulate a locally supersymmetric and
super-Weyl invariant action principle in projective superspace. Some families
of dynamical supergravity-matter systems are presented.Comment: 39 pages; v3: some modifications in section 2; equations (2.3),
(2.14b), (2.16) and (2.17) correcte
Search for star cluster age gradients across spiral arms of three LEGUS disc galaxies
This is the final version. Available from OUP via the DOI in this recordOne of the main theories for explaining the formation of spiral arms in galaxies is the stationary density wave theory. This theory predicts the existence of an age gradient across the arms. We use the stellar cluster catalogues of the galaxies NGC 1566, M51a, and NGC 628 from the Legacy ExtraGalactic UV Survey (LEGUS) program. In order to test for the possible existence of an age sequence across the spiral arms, we quantified the azimuthal offset between star clusters of different ages in our target galaxies. We found that NGC 1566, a grand-design spiral galaxy with bisymmetric arms and a strong bar, shows a significant age gradient across the spiral arms that appear to be consistent with the prediction of the stationary density wave theory. In contrast, M51a with its two well-defined spiral arms and a weaker bar does not show an age gradient across the arms. In addition, a comparison with non-LEGUS star cluster catalogues for M51a yields similar results. We believe that the spiral structure of M51a is not the result of a stationary density wave with a fixed pattern speed. Instead, tidal interactions could be the dominant mechanism for the formation of spiral arms. We also found no offset in the azimuthal distribution of star clusters with different ages across the weak spiral arms of NGC 628.This work is based on observations made with the NASA/ESA HST, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. These observations are associated with program 13364. Support for Program 13364 was provided by NASA through a grant from the Space Telescope Science Institute.
This research has made use of the NED, which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration.
AA acknowledges the support of the Swedish Research Council (VetenskapsrĂĄdet) and the Swedish National Space Board. DAG kindly acknowledges financial support by the German Research Foundation (DFG) through programme GO 1659/3-2
- …