1,689 research outputs found
Development and fabrication of improved Schottky power diodes, phases I and II
Reproducible methods for the fabrication of silicon Schottky diodes were developed for the metals tungsten, aluminum, conventional platinum silicide and low temperature platinum silicide. Barrier heights and barrier lowering were measured permitting the accurate prediction of ideal forward and reverse diode performance. Processing procedures were developed which permit the fabrication of large area (approximately 1 sqcm) mesa-geometry power Schottky diodes with forward and reverse characteristics that approach theoretical values
National Endowment for the Arts v. Finley: Challenging the Facial Challenge
This Note examines the facial challenge in National Endowment for the Arts ( NEA ) v. Finley and how an as-applied challenge may have produced a different outcome. In particular, this Note will analyze the inadequacy of a facial challenge to the decency & respect provision, and in the alternative how an asapplied challenge would have invalidated the provision when applied to artists such as the Respondents in Finley
Development and fabrication of improved Schottky power diodes
Reproducible methods for the fabrication of silicon Schottky diodes have been developed for tungsten, aluminum, conventional platinum silicide, and low temperature platinum silicide. Barrier heights and barrier lowering under reverse bias have been measured, permitting the accurate prediction of forward and reverse diode characteristics. Processing procedures have been developed that permit the fabrication of large area (about 1 sq cm) mesageometry power Schottky diodes with forward and reverse characteristics that approach theoretical values. A theoretical analysis of the operation of bridge rectifier circuits has been performed, which indicates the ranges of frequency and voltage for which Schottky rectifiers are preferred to p-n junctions. Power Schottky rectifiers have been fabricated and tested for voltage ratings up to 140 volts
A New Species of Basicladia from the Snail Viviparus Malleatus Reeve
Author Institution: Department of Zoology and Entomology and Department of Botany and Plant Pathology, The Ohio State Universit
The Age of the Inner Halo Globular Cluster NGC 6652
HST (V,I) photometry has been obtained for the inner halo globular cluster
NGC 6652. The photometry reaches approximately 4 mag below the turn-off and
includes a well populated horizontal branch. This cluster is located close to
the Galactic center at a galactocentric distance of approximately 2.0 kpc with
a reddening of E(V-I) = 0.15 +/- 0.02 and has a metallicity of [Fe/H]
approximately -0.85. Based upon Delta(V) between the point on the sub-giant
branch which is 0.05 mag redder than the turn-off and the horizontal branch,
NGC 6652 is 11.7 +/- 1.6 Gyr old. Using this same Delta(V), precise
differential ages for 47 Tuc (a thick disk globular), M107 and NGC 1851 (both
halo clusters) were obtained. NGC 6652 appears to be the same age as 47 Tuc and
NGC 1851 (within +/- 1.2 Gyr), while there is a slight suggestion that M107 is
older than NGC 6652 by 2.3 +/- 1.5 Gyr. As this is a less than 2-sigma result,
this issue needs to be investigated further before a definitive statement
regarding the relative age of M107 and NGC 6652 may be made.Comment: accepted for publication in the Astronomical Journal, December 2000
issu
A Survey for Low-Surface-Brightness Galaxies Around M31. I. The Newly Discovered Dwarf Andromeda V
We present images and a color-magnitude diagram for And V, a new dwarf
spheroidal companion to M31 that was found using a digital filtering technique
applied to 1550 square degrees of the second Palomar Sky Survey. And V resolves
into stars easily in follow-up 4-m V- and I-band images, from which we deduce a
distance of 810 +/- 45 kpc using the tip of the red giant branch method. Within
the uncertainties, this distance is identical to the Population II distances
for M31 and, combined with a projected separation of 112 kpc, provides strong
support for a physical association between the two galaxies. There is no
emission from And V detected in H alpha, 1.4 GHz radio continuum, or IRAS
bandpasses, and there is no young population seen in the color-magnitude
diagram that might suggest that And V is an irregular. Thus, the classification
as a new dwarf spheroidal member of the Local Group seems secure. With an
extinction-corrected central surface brightness of 25.2 V mag per square
arcsec, a mean metal abundance of [Fe/H] approximately -1.5, and no evidence
for upper AGB stars, And V resembles And I & III.Comment: Accepted for publication in The Astronomical Journal, November 1998
issue; 4 embedded PostScript figures, 4 JPEG figures; see
http://aloe.tuc.noao.edu/jacoby/dwarfs.html for a complete full-resolution
PostScript versio
Women with a Reduced Ovarian Complement May Have an Increased Risk for a Child with Down Syndrome
Advanced maternal age is the only well-established risk factor for trisomy 21 Down syndrome (DS), but the basis of the maternal-age effect is not known. In a population-based, case-control study of DS, women who reported surgical removal of all or part of an ovary or congenital absence of one ovary were significantly more likely to have delivered a child with DS than were women who did not report a reduced ovarian complement (odds ratio 9.61; 95% confidence interval 1.18–446.3). Because others have observed that women who have had an ovary removed exhibit elevated levels of FSH and similar hallmarks of advanced maternal age, our finding suggests that the physiological status of the ovary is key to the maternal-age effect. In addition, it suggests that women with a reduced ovarian complement should be offered prenatal diagnosis
Heisenberg realization for U_q(sln) on the flag manifold
We give the Heisenberg realization for the quantum algebra , which
is written by the -difference operator on the flag manifold. We construct it
from the action of on the -symmetric algebra by the
Borel-Weil like approach. Our realization is applicable to the construction of
the free field realization for the [AOS].Comment: 10 pages, YITP/K-1016, plain TEX (some mistakes corrected and a
reference added
Anisotropy of graphite optical conductivity
The graphite conductivity is evaluated for frequencies between
0.1 eV, the energy of the order of the electron-hole overlap, and 1.5 eV, the
electron nearest hopping energy. The in-plane conductivity per single atomic
sheet is close to the universal graphene conductivity and,
however, contains a singularity conditioned by peculiarities of the electron
dispersion. The conductivity is less in the direction by the factor of the
order of 0.01 governed by electron hopping in this direction.Comment: 3 pages, 3 figure
Model Exact Low-Lying States and Spin Dynamics in Ferric Wheels; Fe to Fe
Using an efficient numerical scheme that exploits spatial symmetries and
spin-parity, we have obtained the exact low-lying eigenstates of exchange
Hamiltonians for ferric wheels up to Fe. The largest calculation
involves the Fe ring which spans a Hilbert space dimension of about 145
million for M=0 subspace. Our calculated gaps from the singlet ground state
to the excited triplet state agrees well with the experimentally measured
values. Study of the static structure factor shows that the ground state is
spontaneously dimerized for ferric wheels. Spin states of ferric wheels can be
viewed as quantized states of a rigid rotor with the gap between the ground and
the first excited state defining the inverse of moment of inertia. We have
studied the quantum dynamics of Fe as a representative of ferric wheels.
We use the low-lying states of Fe to solve exactly the time-dependent
Schr\"odinger equation and find the magnetization of the molecule in the
presence of an alternating magnetic field at zero temperature. We observe a
nontrivial oscillation of magnetization which is dependent on the amplitude of
the {\it ac} field. We have also studied the torque response of Fe as a
function of magnetic field, which clearly shows spin-state crossover.Comment: Revtex, 24 pages, 8 eps figure
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