1,783 research outputs found
Collision Integrals for the Exponential Attractive Potential
Numerical integration calculation of collision integrals for exponential attractive potential of gase
Potassium Relationships of Three Ohio Soils
Author Institution: The Ohio State University Agricultural Technical Institute; Department of Agronomy, The Ohio State UniversityThree Ohio soils, Hoytville clay, Brookston silty clay loam, and Wooster silt loam located at various branches of the Ohio Agricultural Research and Development Center, were studied. Bulk samples from each horizon were tested for exchangeable basic cations, pH, sulfuric acid extractable potassium (K+), and particle-size distribution. The surface horizons of each soil were characterized by measurement of cation exchange capacity, quantity-intensity adsorption isotherms for K+ and x-ray diffraction of the clay ( times greater than that for Wooster. Hoytville clay was predominantly illitic while the Brookston and Wooster clays were of a more mixed mineralogical nature. The potassium content and crystallinity of the illite in the Hoytville clay is lower than those of the Brookston and Wooster clays
Hyper-Raman scattering analysis of the vibrations in vitreous boron oxide
Hyper-Raman scattering has been measured on vitreous boron oxide,
BO. This spectroscopy, complemented with Raman scattering and
infrared absorption, reveals the full set of vibrations that can be observed
with light. A mode analysis is performed based on the local D symmetry
of BO triangles and BO boroxol rings. The results show that in
BO the main spectral components can be succesfully assigned using
this relatively simple model. In particular, it can be shown that the
hyper-Raman boson peak arises from external modes that correspond mainly to
librational motions of rigid boroxol rings.Comment: 13 pages, 11 figures, 2 table
Inverse monoids and immersions of 2-complexes
It is well known that under mild conditions on a connected topological space
, connected covers of may be classified via conjugacy
classes of subgroups of the fundamental group of . In this paper,
we extend these results to the study of immersions into 2-dimensional
CW-complexes. An immersion between
CW-complexes is a cellular map such that each point has a
neighborhood that is mapped homeomorphically onto by . In order
to classify immersions into a 2-dimensional CW-complex , we need to
replace the fundamental group of by an appropriate inverse monoid.
We show how conjugacy classes of the closed inverse submonoids of this inverse
monoid may be used to classify connected immersions into the complex
A Detailed Model Atmosphere Analysis of Cool White Dwarfs in the Sloan Digital Sky Survey
We present optical spectroscopy and near-infrared photometry of 126 cool
white dwarfs in the Sloan Digital Sky Survey (SDSS). Our sample includes high
proper motion targets selected using the SDSS and USNO-B astrometry and a dozen
previously known ultracool white dwarf candidates. Our optical spectroscopic
observations demonstrate that a clean selection of large samples of cool white
dwarfs in the SDSS (and the SkyMapper, Pan-STARRS, and the Large Synoptic
Survey Telescope datasets) is possible using a reduced proper motion diagram
and a tangential velocity cut-off (depending on the proper motion accuracy) of
30 km/s. Our near-infrared observations reveal eight new stars with significant
absorption. We use the optical and near-infrared photometry to perform a
detailed model atmosphere analysis. More than 80% of the stars in our sample
are consistent with either pure hydrogen or pure helium atmospheres. However,
the eight stars with significant infrared absorption and the majority of the
previously known ultracool white dwarf candidates are best explained with mixed
hydrogen and helium atmosphere models. The age distribution of our sample is
consistent with a Galactic disk age of 8 Gyr. A few ultracool white dwarfs may
be as old as 12-13 Gyr, but our models have problems matching the spectral
energy distributions of these objects. There are only two halo white dwarf
candidates in our sample. However, trigonometric parallax observations are
required for accurate mass and age determinations and to confirm their
membership in the halo.Comment: ApJ Supplements, in pres
Spectroscopy of Quasar Candidates from SDSS Commissioning Data
The Sloan Digital Sky Survey has obtained images in five broad-band colors
for several hundred square degrees. We present color-color diagrams for stellar
objects, and demonstrate that quasars are easily distinguished from stars by
their distinctive colors. Follow-up spectroscopy in less than ten nights of
telescope time has yielded 22 new quasars, 9 of them at , and one with
, the second highest-redshift quasar yet known. Roughly 80% of the
high-redshift quasar candidates selected by color indeed turn out to be
high-redshift quasars.Comment: 4 pages, 3 figures, to appear in the proceedings of "After the Dark
Ages: When Galaxies were Young (the Universe at 2<z<5)", 9th Annual October
Astrophysics Conference in Marylan
Factors Affecting Mississippi’s NIPF Landowners’ Reforestation Decisions
Non-industrial private forest (NIPF) landowners have played an increasingly important role in the nation\u27s timber economy. Nearly 70% of the forestland in the South is owned by NIPF landowners (Powell et al., 1994). In Mississippi alone, these landowners control approximately 66% of the state\u27s forestland base (Hartsell and London, 1995). Therefore, NIPF landowners are expected to provide a large portion of the state\u27s supply of timber. However, whether they do so depends largely on how their timberlands are managed. Forest management decisions of NIPF landowners can impact future timber supply due to the magnitude of their collective ownership
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