3,378 research outputs found
Testing the usefulness of ERTS-1 imagery for inventorying wildland resources in northern California
The usefulness of ERTS-1 imagery for inventorying wildland resources in northern California is discussed. Studies are being conducted in two large wildland areas, namely, the Feather River Watershed and the Northern Coastal Zone. The 2.5 million-acre Feather River headwaters area in northern California is the keystone watershed for the California Water Project, one of the most extensive and ambitious water resource developments ever attempted. Consequently, accurate and timely information on the quantity, quality and distribution of timber, forage, water and recreational resources is of immediate importance to each public agency and private group managing this vast, but inaccessible, wildland area. The Northern Coastal Zone (consisting of the counties of Marin, Sonoma, Mendicino, Humbolt and Del Norte) is relatively rural, with an economy based on agriculture, timber, commercial fishing and tourism. However, it is expected that intensive resource use resulting from increasing population will soon become a serious problem unless wise land use planning is undertaken. Thus, this coastal region is particularly well suited to investigations of the ways in which ERTS-1 imagery and other supporting data may be used in conducting land use evaluations
Marital Status and Car Ownership as Related to Sex Differences in Traffic Accidents and Violations in a Two-Year Period
On the basis of considerable previous work in the collection and tabulation of motor vehicle accidents and traffic violations, the hypothesis that women are better accident risks than men has come to be widely accepted. According to Lauer (3) even when corrections are made for age and amount of driving exposure, women have fewer reported accidents and violations than men. Using this past information as a basis of approach, the present study was made in order to determine if the same relationships hold when the additional factors of marital status and car ownership are considered. Instead of asking questions of the form, Do men have~ more accidents than women? , this study was interested in questions such as, Do married men who own automobiles have more accidents than married women who own automobiles?\u27\u27 Essentially the purpose of the present study was to control on two variables which had hitherto been uncontrolled in comparisons of traffic accidents and violations between the sexes. The data which were available for use were such that only a partial answer to the problem could be obtained, but the information which was gathered was a start in this direction and suggested important future research to be done in the area
The Nuclear Stellar Disk in Andromeda: A Fossil from the Era of Black Hole Growth
The physics of angular momentum transport from galactic scales (~10-100 pc)
to much smaller radii is one of the oustanding problems in our understanding of
the formation and evolution of super-massive black holes (BHs). Seemingly
unrelated observations have discovered that there is a lopsided stellar disk of
unknown origin orbiting the BH in M31, and possibly many other systems. We show
that these nominally independent puzzles are in fact closely related.
Multi-scale simulations of gas inflow from galactic to BH scales show that when
sufficient gas is driven towards a BH, gravitational instabilities form a
lopsided, eccentric disk that propagates inwards from larger radii. The
lopsided stellar disk exerts a strong torque on the remaining gas, driving
inflows that fuel the growth of the BH and produce quasar-level luminosities.
The same disk can produce significant obscuration along many sightlines and
thus may be the putative 'torus' invoked to explain obscured active galactic
nuclei and the cosmic X-ray background. The stellar relic of this disk is long
lived and retains the eccentric pattern. Simulations that yield quasar-level
accretion rates produce relic stellar disks with kinematics, eccentric
patterns, precession rates, and surface density profiles in reasonable
agreement with observations of M31. The observed properties of nuclear stellar
disks can thus be used to constrain the formation history of super-massive BHs.Comment: 6 pages, 4 figures, accepted to MNRAS Letters (matches published
version
A Non-Parametric Estimate of Mass 'Scoured' in Galaxy Cores
We present a simple estimate of the mass 'deficits' in cored spheroids, as a
function of galaxy mass and radius within the galaxy. Previous attempts to
measure such deficits depended on fitting some functional form to the profile
at large radii and extrapolating inwards; this is sensitive to the assumed
functional form and does not allow for variation in nuclear profile shapes. We
take advantage of larger data sets to directly construct stellar mass profiles
of observed systems and measure the stellar mass enclosed in a series of
physical radii (M(<R)), for samples of cusp and core spheroids at the same
stellar mass. There is a significant bimodality in this distribution at small
radii, and we non-parametrically measure the median offset between core and
cusp populations (the deficit Delta_M(<R)). We construct the scoured mass
profile as a function of radius, without reference to any assumed functional
form. The mass deficit rises in power-law fashion (Delta_M(<R) R^{1.3-1.8})
from a significant but small mass at R<10pc, to asymptote to a maximum ~0.5-2
M_BH at ~100pc. At larger radii there is no statistically significant
separation between populations; the upper limit to the cumulative scoured mass
at ~kpc is ~2-4 M_BH. This does not depend strongly on stellar mass. The
dispersion in M(<R) appears larger in the core population, possibly reflecting
the fact that scouring increases the scatter in profile shapes. These results
are in good agreement with models of scouring from BH binary systems.Comment: 11 pages, 5 figures, accepted to MNRA
Bremsstrahlung in alpha-Decay Reexamined
A high-statistics measurement of bremsstrahlung emitted in the alpha decay of
210Po has been performed, which allows to follow the photon spectra up to
energies of ~ 500 keV. The measured differential emission probability is in
good agreement with our theoretical results obtained within the quasi classical
approximation as well as with the exact quantum mechanical calculation. It is
shown that due to the small effective electric dipole charge of the radiating
system a significant interference between the electric dipole and quadrupole
contributions occurs, which is altering substantially the angular correlation
between the alpha particle and the emitted photon.Comment: 10 pages, 5 figures, v2: fix of small typo
A Novel Hybrid CNN-AIS Visual Pattern Recognition Engine
Machine learning methods are used today for most recognition problems.
Convolutional Neural Networks (CNN) have time and again proved successful for
many image processing tasks primarily for their architecture. In this paper we
propose to apply CNN to small data sets like for example, personal albums or
other similar environs where the size of training dataset is a limitation,
within the framework of a proposed hybrid CNN-AIS model. We use Artificial
Immune System Principles to enhance small size of training data set. A layer of
Clonal Selection is added to the local filtering and max pooling of CNN
Architecture. The proposed Architecture is evaluated using the standard MNIST
dataset by limiting the data size and also with a small personal data sample
belonging to two different classes. Experimental results show that the proposed
hybrid CNN-AIS based recognition engine works well when the size of training
data is limited in siz
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