3,625 research outputs found
Research in interactive scene analysis
An interactive scene interpretation system (ISIS) was developed as a tool for constructing and experimenting with man-machine and automatic scene analysis methods tailored for particular image domains. A recently developed region analysis subsystem based on the paradigm of Brice and Fennema is described. Using this subsystem a series of experiments was conducted to determine good criteria for initially partitioning a scene into atomic regions and for merging these regions into a final partition of the scene along object boundaries. Semantic (problem-dependent) knowledge is essential for complete, correct partitions of complex real-world scenes. An interactive approach to semantic scene segmentation was developed and demonstrated on both landscape and indoor scenes. This approach provides a reasonable methodology for segmenting scenes that cannot be processed completely automatically, and is a promising basis for a future automatic system. A program is described that can automatically generate strategies for finding specific objects in a scene based on manually designated pictorial examples
Partonic Energy Loss and the Drell-Yan Process
We examine the current status of the extraction of the rate of partonic
energy loss in nuclei from A dependent data. The advantages and difficulties of
using the Drell-Yan process to measure the energy loss of a parton traversing a
cold nuclear medium are discussed. The prospects of using relatively low energy
proton beams for a definitive measurement of partonic energy loss are
presented.Comment: 12 pages, 2 figure
Probing Nucleon Strangeness with Neutrinos: Nuclear Model Dependences
The extraction of the nucleon's strangeness axial charge, Delta_s, from
inclusive, quasielastic neutral current neutrino cross sections is studied
within the framework of the plane-wave impulse approximation. We find that the
value of Delta_s can depend significantly on the choice of nuclear model used
in analyzing the quasielastic cross section. This model-dependence may be
reduced by one order of magnitude when Delta_s is extracted from the ratio of
total proton to neutron yields. We apply this analysis to the interpretation of
low-energy neutrino cross sections and arrive at a nuclear theory uncertainty
of plus/minus 0.03 on the value of Delta_s expected to be determined from the
ratio of proton and neutron yields measured by the LSND collaboration. This
error compares favorably with estimates of the SU(3)-breaking uncertainty in
the value of Delta_s extracted from inclusive, polarized deep-inelastic
structure function measurements. We also point out several general features of
the quasielastic neutral current neutrino cross section and compare them with
the analogous features in inclusive, quasielastic electron scattering.Comment: 40 pages (including 11 postscript figures), uses REVTeX and
epsfig.st
The Angular Correlations in the Decay of Excited States in 8Be
Motivated by the recent observation of anomalous electron-positron angular
correlations in the decay of the 18.15 MeV 1+ excited states in 8Be, we
reexamine in detail the Standard Model expectations for these angular
correlations. The 18.15 MeV state is above particle threshold, and several
multipoles can contribute to its decay. We present the general
theoretical expressions for angular distributions for nuclear decay by
C0, C1, C2 M1, E1, and E2 multipoles, and we examine their relative
contribution to the decay of 8Be at 18.15 MeV. We find that this
resonance is dominated by M1 and E1 decay, and that the ratio of M1 to E1
strength is a strong function of energy. This is in contract to the original
analysis of the angular distributions, where the M1/E1 ratio was
assumed to be a constant over the energy region Ep = 0:8-1:2 MeV. We find that
the existence of a `bump' in the measured angular distribution is strongly
dependent on the assumed M1/E1 ratio, with the present analysis finding the
measured large-angle contributions to the angular distribution to be
lower than expectation. Thus, in the current analysis we find no evidence for
axion decay in the 18.15 MeV resonance region of 8Be
Why, what, and how? case study on law, risk, and decision making as necessary themes in built environment teaching
The paper considers (and defends) the necessity of including legal studies as a core part of built environment undergraduate and postgraduate curricula. The writer reflects upon his own experience as a lawyer working alongside and advising built environment professionals in complex land remediation and site safety management situations in the United Kingdom and explains how themes of liability, risk, and decision making can be integrated into a practical simulation in order to underpin more traditional lecture-based law teaching. Through reflection upon the writer's experiments with simulation-based teaching, the paper suggests some innovations that may better orientate law teaching to engage these themes and, thereby, enhance the relevance of law studies to the future needs of built environment professionals in practice.</p
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