78,848 research outputs found
Graph inverse semigroups: their characterization and completion
Graph inverse semigroups generalize the polycyclic inverse monoids and play
an important role in the theory of C*-algebras. This paper has two main goals:
first, to provide an abstract characterization of graph inverse semigroups; and
second, to show how they may be completed, under suitable conditions, to form
what we call the Cuntz-Krieger semigroup of the graph. This semigroup is the
ample semigroup of a topological groupoid associated with the graph, and the
semigroup analogue of the Leavitt path algebra of the graph.Comment: Some minor corrections made and tangential material remove
Encouraging the perceptual underdog: positive affective priming of nonpreferred localâglobal processes
Two experiments examined affective priming of global and local perception. Participants attempted to detect a target that might be present as either a global or a local shape. Verbal primes were used in 1 experiment, and pictorial primes were used in the other. In both experiments, positive primes led to improved performance on the nonpreferred dimension. For participants exhibiting global precedence, detection of local targets was significantly improved, whereas for participants exhibiting local precedence, detection of global targets was significantly improved. The results provide support for an interpretation of the effects of positive affective priming in terms of increased perceptual flexibility
Migration of latent fingermarks on non-porous surfaces:observation technique and nanoscale variations
Latent fingermark morphology was examined over a period of approximately two months. Variation in topography was observed with atomic force microscopy and the expansion of the fingermark occurred in the form of the development of an intermediate area surrounding the main fingermark ridge. On an example area of a fingermark on silicon, the intermediate region exists as a uniform 4nm thick deposit; on day 1 after deposition this region extends approximately 2”m from the edge of the main ridge deposit and expands to a maximum of ~ 4”m by day 23. Simultaneously the region breaks up, the integrity is compromised by day 16, and by day 61 the area resembles a series of interconnected islands, with coverage of approximately 60%. Observation of a similar immediate area and growth with time on surfaces such as Formica was possible by monitoring the mechanical characteristics of the fingermark and surfaces though phase contrast in tapping mode AFM. The presence of this area may affect fingermark development, for example affecting the gold distribution in vacuum metal deposition. Further study of time dependence and variation with donor may enable assessment of this area to be used to evaluate the age of fingermarks
A shock wave study of Coconino sandstone
Hugoniot equation of state measurements from shock wave loading study of Coconino sandston
Wakefield damping for the CLIC crab cavity
A crab cavity is required in the CLIC to allow effective head-on collision of
bunches at the IP. A high operating frequency is preferred as the deflection
voltage required for a given rotation angle and the RF phase tolerance for a
crab cavity are inversely proportional to the operating frequency. The short
bunch spacing of the CLIC scheme and the high sensitivity of the crab cavity to
dipole kicks demand very high damping of the inter-bunch wakes, the major
contributor to the luminosity loss of colliding bunches. This paper
investigates the nature of the wakefields in the CLIC crab cavity and the
possibility of using various damping schemes to suppress them effectively
Propagation of Light Elements in the Galaxy
The origin and evolution of isotopes of the lightest elements H2, He3, Li,
Be, B in the universe is a key problem in such fields as astrophysics of CR,
Galactic evolution, non-thermal nucleosynthesis, and cosmological studies. One
of the major sources of these species is spallation by CR nuclei in the
interstellar medium. On the other hand, it is the B/C ratio in CR and Be10
abundance which are used to fix the propagation parameters and thus the
spallation rate. We study the production and Galactic propagation of isotopes
of elements Z<6 using the numerical propagation code GALPROP and updated
production cross sections.Comment: 4 pages, 6 ps-figures, tsukuba.sty, to appear in the Proc. 28th
International Cosmic Ray Conference (Tsukuba, Japan 2003). More details can
be found at http://www.gamma.mpe-garching.mpg.de/~aws/aws.htm
Evaluation of enzyme immunoassays in the diagnosis of camel (Camelus dromedarius) trypanosomiasis:a preliminary investigation
Three enzyme immunoassays were used for the serodiagnosis of Trypanosoma evansi in camels in the Sudan in order to evaluate their ability to discriminate between infected and non-infected animals. Two assays were used for the detection of trypanosomal antibodies, one using specific anti-camel IgG conjugate and another using a non-specific Protein A conjugate. The third assay detected the presence of trypanosomal antigens using anti-T. evansi antibodies in a double antibody sandwich assay. Inspection of the frequency distribution of assay results suggested that the ELISA for circulating trypanosomal antibodies using specific antisera and the ELISA for circulating antigens can distinguish between non-infected camels and infected camels exhibiting patent infections or not. The ELISA using Protein A conjugate to bind non-specifically to camel immunoglobulin did not appear to discriminate between infected and non-infected animals
Form Factors from a Relativistic Dynamical Model of Pion Electroproduction
We obtain the electromagnetic form factors of the transition
by analyzing recent pion-electroproduction data using a fully relativistic
dynamical model. Special care is taken to satisfy Ward-Takahashi identities for
the Born term in the presence of form factors thereby allowing the use of
realistic electromagnetic form factors of the nucleon and pion. We parametrize
the dependence of the {\it bare} form factors by a
three-parameter form which is consistent with the asymptotic behavior inferred
from QCD. The parameters of the bare form factors are the
only free parameters of the model and are fitted to the differential
cross-section and multipole-analysis data up to (GeV/c) in the
-resonance region. This analysis emphasizes the significance of
the pion-cloud effects in the extraction of the resonance parameters.Comment: 9 pages, 5 figures, several small corrections, to be published in
Phys. Rev.
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