4,984 research outputs found
Black Symposium Correspondence Between W. Linwood Chase and Stephen Hughes on Appreciating the Symposium on Black America
A letter from University of Maine alumnus W. Linwood Chase, Class of 1920, to Stephen T. Hughes, Student Senate President at the University of Maine, sent on January 14, 1969 in regards to an interview Stephen Hughes gave on The Distinguished Lecture Series featuring the Symposium on Black America. W. Linwood Chase hoped that the symposium would bring attention to the problems of Black America.
Stephen Hughes letter in response to W. Linwood Chase on January 17, 1969 sends thanks and best wishes and appreciated the encouraging remarks on the Symposium of Black America
Black Symposium_Correspondence Between W. Linwood Chase and Stephen Hughes on Appreciating the Symposium on Black America
A letter from University of Maine alumnus W. Linwood Chase, Class of 1920, to Stephen T. Hughes, Student Senate President at the University of Maine, sent on January 14, 1969 in regards to an interview Stephen Hughes gave on The Distinguished Lecture Series featuring the Symposium on Black America. W. Linwood Chase hoped that the symposium would bring attention to the problems of Black America.
Stephen Hughes letter in response to W. Linwood Chase on January 17, 1969 sends thanks and best wishes and appreciated the encouraging remarks on the Symposium of Black America.https://digitalcommons.library.umaine.edu/racial_justice/1022/thumbnail.jp
Chemical Equilibrium Abundances in Brown Dwarf and Extrasolar Giant Planet Atmospheres
We calculate detailed chemical abundance profiles for a variety of brown
dwarf and extrasolar giant planet atmosphere models, focusing in particular on
Gliese 229B, and derive the systematics of the changes in the dominant
reservoirs of the major elements with altitude and temperature. We assume an
Anders and Grevesse (1989) solar composition of 27 chemical elements and track
330 gas--phase species, including the monatomic forms of the elements, as well
as about 120 condensates. We address the issue of the formation and composition
of clouds in the cool atmospheres of substellar objects and explore the rain
out and depletion of refractories. We conclude that the opacity of clouds of
low--temperature (900 K), small--radius condensibles (specific chlorides
and sulfides), may be responsible for the steep spectrum of Gliese 229B
observed in the near infrared below 1 \mic. Furthermore, we assemble a
temperature sequence of chemical transitions in substellar atmospheres that may
be used to anchor and define a sequence of spectral types for substellar
objects with Ts from 2200 K to 100 K.Comment: 57 pages total, LaTeX, 14 figures, 5 tables, also available in
uuencoded, gzipped, and tarred form via anonymous ftp at
www.astrophysics.arizona.edu (cd to pub/burrows/chem), submitted to Ap.
InSb charge coupled infrared imaging device: The 20 element linear imager
The design and fabrication of the 8585 InSb charge coupled infrared imaging device (CCIRID) chip are reported. The InSb material characteristics are described along with mask and process modifications. Test results for the 2- and 20-element CCIRID's are discussed, including gate oxide characteristics, charge transfer efficiency, optical mode of operation, and development of the surface potential diagram
Adaptive constraints for feature tracking
In this paper extensions to an existing tracking algorithm are described.
These extensions implement adaptive tracking constraints in the form
of regional upper-bound displacements and an adaptive track smoothness
constraint. Together, these constraints make the tracking algorithm
more flexible than the original algorithm (which used fixed tracking
parameters) and provide greater confidence in the tracking results.
The result of applying the new algorithm to high-resolution ECMWF
reanalysis data is shown as an example of its effectiveness
Vacuum-UV negative photoion spectroscopy of CF3Cl, CF3Br and CF3I
Using synchrotron radiation negative ions have been detected by mass spectrometry following vacuum-UV photoexcitation of trifluorochloromethane (CFCl), trifluorobromomethane (CFBr) and trifluoroiodomethane (CFI). The anions F, X, F, FX, CF, CF and CF were observed from all three molecules, where X = Cl, Br or I, and their ion yields recorded in the range 8-35 eV. With the exception of Br and I, the anions observed show a linear dependence of signal with pressure, showing that they arise from unimolecular ion-pair dissociation. Dissociative electron attachment, following photoionization of CFBr and CFI as the source of low-energy electrons, is shown to dominate the observed Br and I signals, respectively. Cross sections for ion-pair formation are put on to an absolute scale by calibrating the signal strengths with those of F from both SF and CF. These anion cross sections are normalized to vacuum-UV absorption cross sections, where available, and the resulting quantum yields are reported. Anion appearance energies are used to calculate upper limits to 298 K bond dissociation energies for (CF-X) which are consistent with literature values. We report new data for (CFI-F) †2.7 ± 0.2 eV and (CFI) †(598 ± 22) kJ mol. No ion-pair formation is observed below the ionization energy of the parent molecule for CFCl and CFBr, and only weak signals (in both I and F) are detected for CFI. These observations suggest neutral photodissociation is the dominant exit channel to Rydberg state photoexcitation at these lower energies
Expert chess memory: Revisiting the chunking hypothesis
After reviewing the relevant theory on chess expertise, this paper re-examines experimentally the finding of Chase and Simon (1973a) that the differences in ability of chess players at different skill levels to copy and to recall positions are attributable to the experts' storage of thousands of chunks (patterned clusters of pieces) in long-term memory. Despite important differences in the experimental apparatus, the data of the present experiments regarding latencies and chess relations between successively placed pieces are highly correlated with those of Chase and Simon. We conclude that the 2-second inter-chunk interval used to define chunk boundaries is robust, and that chunks have psychological reality. We discuss the possible reasons why Masters in our new study used substantially larger chunks than the Master of the 1973 study, and extend the chunking theory to take account of the evidence for large retrieval structures (templates) in long-term memory
Structure of the western Somali Basin
Originally issued as Reference No. 67-38, series later renamed WHOI-. Reprint from Journal of Geophysical Research, vol. 72, no. 10, May 1967.The western Somali Basin in the northwestern Indian Ocean is covered by thick deposits
of terrigenous sediments. Seismic reflection profiles show, however, the northern and southern
parts to be very different. The northern sections is a deep basin filled with thick uniformly
stratified sediments. It is enclosed by the continental margin to the west and north,
Chain ridge to the east, and shallow basement structure to the south. A change in depth
of basement occurs along an approximately east-west line at latitude 3°30'N very near the
southern end of Chain ridge. In the southern portion of the basin the basement is shallow,
and, immediately south of latitude 3°30'N, it has high relief. Stratified flat-lying sediments
fill the basement depressions, and isolated hills formed of basement material rise above the
abyssal plain deposits. Farther to the south the abyssal plain becomes very narrow. Gabbro
dredged from the southeast slope of Chain ridge has been dated by the potassium-argon
method as 89.6 ± 4.5 m.y., which should be considered a minimum age. The evidence suggests
that the entire sediment sequence of the northern basin was deposited subsequent to
the formation of the ridge. The thin sediment cover of the southern portion of the basin is
probably no older than Tertiary.Office of Naval Research under contract
Nonr-4029(00) NR 260-101
Gravitationally Collapsing Shells in (2+1) Dimensions
We study gravitationally collapsing models of pressureless dust, fluids with
pressure, and the generalized Chaplygin gas (GCG) shell in (2+1)-dimensional
spacetimes. Various collapse scenarios are investigated under a variety of the
background configurations such as anti-de Sitter(AdS) black hole, de Sitter
(dS) space, flat and AdS space with a conical deficit. As with the case of a
disk of dust, we find that the collapse of a dust shell coincides with the
Oppenheimer-Snyder type collapse to a black hole provided the initial density
is sufficiently large. We also find -- for all types of shell -- that collapse
to a naked singularity is possible under a broad variety of initial conditions.
For shells with pressure this singularity can occur for a finite radius of the
shell. We also find that GCG shells exhibit diverse collapse scenarios, which
can be easily demonstrated by an effective potential analysis.Comment: 27 pages, Latex, 11 figures, typos corrected, references added, minor
amendments in introduction and conclusion introd
Atomic and Molecular Opacities for Brown Dwarf and Giant Planet Atmospheres
We present a comprehensive description of the theory and practice of opacity
calculations from the infrared to the ultraviolet needed to generate models of
the atmospheres of brown dwarfs and extrasolar giant planets. Methods for using
existing line lists and spectroscopic databases in disparate formats are
presented and plots of the resulting absorptive opacities versus wavelength for
the most important molecules and atoms at representative temperature/pressure
points are provided. Electronic, ro-vibrational, bound-free, bound-bound,
free-free, and collision-induced transitions and monochromatic opacities are
derived, discussed, and analyzed. The species addressed include the alkali
metals, iron, heavy metal oxides, metal hydrides, , , , ,
, , , and representative grains. [Abridged]Comment: 28 pages of text, plus 22 figures, accepted to the Astrophysical
Journal Supplement Series, replaced with more compact emulateapj versio
- âŠ