5,877 research outputs found
Ohio's statewide land use inventory: An operational approach for applying LANDSAT data to state, regional and local planning programs
The programmatic, technical, user application, and cost factors associated with the development of an operational, statewide land use inventory from LANDSAT data are described. The LANDSAT multispectral data are subjected to geometrical and categorical processing to produce map files for each of the 200 fifteen (15) minute quads covering Ohio. Computer compatible tapes are rescanned to produce inventory tapes which identify eight (8) Level I land use categories and a variety of Level II categories. The inventory tapes are processed through a series of ten (10) software programs developed by the State of Ohio. The net result is a computerized inventory which can be displayed in map or tabular form for various geographic units, at a variety of scales and for selected categories of usage. The computerized inventory data files are applied to technical programs developed by the various state agencies to be used in state, regional, and local planning programs
Irreversible Deposition of Line Segment Mixtures on a Square Lattice: Monte Carlo Study
We have studied kinetics of random sequential adsorption of mixtures on a
square lattice using Monte Carlo method. Mixtures of linear short segments and
long segments were deposited with the probability and , respectively.
For fixed lengths of each segment in the mixture, the jamming limits decrease
when increases. The jamming limits of mixtures always are greater than
those of the pure short- or long-segment deposition.
For fixed and fixed length of the short segments, the jamming limits have
a maximum when the length of the long segment increases. We conjectured a
kinetic equation for the jamming coverage based on the data fitting.Comment: 7 pages, latex, 5 postscript figure
Information content of ozone retrieval algorithms
The algorithms are characterized that were used for production processing by the major suppliers of ozone data to show quantitatively: how the retrieved profile is related to the actual profile (This characterizes the altitude range and vertical resolution of the data); the nature of systematic errors in the retrieved profiles, including their vertical structure and relation to uncertain instrumental parameters; how trends in the real ozone are reflected in trends in the retrieved ozone profile; and how trends in other quantities (both instrumental and atmospheric) might appear as trends in the ozone profile. No serious deficiencies were found in the algorithms used in generating the major available ozone data sets. As the measurements are all indirect in someway, and the retrieved profiles have different characteristics, data from different instruments are not directly comparable
The resistance of randomly grown trees
Copyright @ 2011 IOP Publishing Ltd. This is a preprint version of the published article which can be accessed from the link below.An electrical network with the structure of a random tree is considered: starting from a root vertex, in one iteration each leaf (a vertex with zero or one adjacent edges) of the tree is extended by either a single edge with probability p or two edges with probability 1 − p. With each edge having a resistance equal to 1 omega, the total resistance Rn between the root vertex and a busbar connecting all the vertices at the nth level is considered. A dynamical system is presented which approximates Rn, it is shown that the mean value (Rn) for this system approaches (1 + p)/(1 − p) as n → ∞, the distribution of Rn at large n is also examined. Additionally, a random sequence construction akin to a random Fibonacci sequence is used to approximate Rn; this sequence is shown to be related to the Legendre polynomials and its mean is shown to converge with |(Rn) − (1 + p)/(1 − p)| ∼ n−1/2.Engineering and Physical Sciences Research Council (EPSRC
Struvite Crystalluria and Urolithiasis in Cross Labradors
Recurrent struvite crystalluria and urolithiasis in a Cross-Labrador bitch was studied using a combined Coulter-Counter and scanning electron microscope (SEM) approach. Staphylococcus bacteria were cultured from the patient\u27s urine as well as from the calculi themselves. Urine samples were subjected to particle counting and sizing during active and non-active periods of stone formation. Size distribution curves so obtained were identical as were those derived from sterile and non-sterile specimens. These showed a peak incidence at a diameter of 5 μm. Particle sizes for 6 controls were also determined and showed an even distribution over a much wider range with small peaks occurring at 3,10, and 20 μm diameters.
SEM studies of urine sediments revealed the presence of struvite crystals in all the controls as well as in the stone-former. These occurred in a variety of shapes and sizes but were generally larger in the controls. SEM also revealed intimate admixtures of struvite and apatite in calculi surgically removed from the patient.
The results of this study indicate that crystal numbers are of greater significance than crystal size. It is also suggested that Cross-Labradors may be unusually predisposed to struvite crystalluria. The repeated recurrence of struvite urolithiasis in the subject indicates a possible inherent physiological malfunction in the animal\u27s ability to cope with this crystalluria. The absence of a nucleation inhibitor in the stone-farmer\u27s urine is also postulated
An analytic model for a cooperative ballistic deposition in one dimension
We formulate a model for a cooperative ballistic deposition (CBD) process
whereby the incoming particles are correlated with the ones already adsorbed
via attractive force. The strength of the correlation is controlled by a
tunable parameter that interpolates the classical car parking problem at
, the ballistic deposition at and the CBD model at . The
effects of the correlation in the CBD model are as follows. The jamming
coverage increases with the strength of attraction due to an ever
increasing tendency of cluster formation. The system almost reaches the closest
packing structure as but never forms a percolating cluster which
is typical to 1D system. In the large regime, the mean cluster size
increases as . Furthermore, the asymptotic approach towards the
closest packing is purely algebraic both with as and with as where .Comment: 9 pages (in Revtex4), 9 eps figures; Submitted to publicatio
Kinetics of catalysis with surface disorder
We study the effects of generalised surface disorder on the monomer-monomer
model of heterogeneous catalysis, where disorder is implemented by allowing
different adsorption rates for each lattice site. By mapping the system in the
reaction-controlled limit onto a kinetic Ising model, we derive the rate
equations for the one and two-spin correlation functions. There is good
agreement between these equations and numerical simulations. We then study the
inclusion of desorption of monomers from the substrate, first by both species
and then by just one, and find exact time-dependent solutions for the one-spin
correlation functions.Comment: LaTex, 19 pages, 1 figure included, requires epsf.st
Analytical solution of the optimal laser control problem in two-level systems
The optimal control of two-level systems by time-dependent laser fields is
studied using a variational theory. We obtain, for the first time, general
analytical expressions for the optimal pulse shapes leading to global
maximization or minimization of different physical quantities. We present
solutions which reproduce and improve previous numerical results.Comment: 12 pages, 2 figure
The Chemical Compositions of the Type II Cepheids -- The BL Her and W Vir Variables
Abundance analyses from high-resolution optical spectra are presented for 19
Type II Cepheids in the Galactic field. The sample includes both short-period
(BL Her) and long-period (W Vir) stars. This is the first extensive abundance
analysis of these variables. The C, N, and O abundances with similar spreads
for the BL Her and W Vir show evidence for an atmosphere contaminated with
-process and CN-cycling products. A notable anomaly of the BL Her
stars is an overabundance of Na by a factor of about five relative to their
presumed initial abundances. This overabundance is not seen in the W Vir stars.
The abundance anomalies running from mild to extreme in W Vir stars but not
seen in the BL Her stars are attributed to dust-gas separation that provides an
atmosphere deficient in elements of high condensation temperature, notably Al,
Ca, Sc, Ti, and -process elements. Such anomalies have previously been seen
among RV Tau stars which represent a long-period extension of the variability
enjoyed by the Type II Cepheids. Comments are offered on how the contrasting
abundance anomalies of BL Her and W Vir stars may be explained in terms of the
stars' evolution from the blue horizontal branch.Comment: 41 pages including 11 figures and 4 tables; Accepted for publication
in Ap
Nonlinear models of the bump cepheid HV 905 and the distance modulus to the large magellanic cloud
Nonlinear pulsation models have been used to simulate the light curve of the LMC bump Cepheid HV 905. In order to reproduce the light curve accurately, tight constraints on the input parameters M, L, and T-eff are required. The results, combined with accurate existing V and I photometry, yield an LMC distance modulus of 18.51 +/- 0.05, and they show that the luminosity of HV 905 is much higher than expected from the mass-luminosity relation of stellar evolution theory. If we assume that the pulsation models are accurate, this suggests that there is a larger amount of convective core overshoot during the main-sequence evolution of stars with M similar to 5 M. than is usually assumed
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