2,593 research outputs found
Effects of Meson Mass Reduction on the Properties of Neutron Star Matter
We investigate the effects of meson-mass reduction on the properties of the
neutron star matter. We adopt the Brown-Rho scaling law to take into account
density dependence of meson masses in the quantum hadrodynamics, quark-meson
coupling and modified quark-meson coupling models. It is found that the
equation of state becomes stiff when the mass of meson is reduced in dense
medium. We discuss its implication on the properties of the neutron star.Comment: 3 pages, 2 figures and 10 references. Use espcrc1.sty. Appeared in
the proceedings of the 7th international symposium on Nuclei in the Cosmos,
Fuji-Yoshida, Japan, July 8-12, 200
The topological dimension of type I C*-algebras
While there is only one natural dimension concept for separable, metric
spaces, the theory of dimension in noncommutative topology ramifies into
different important concepts. To accommodate this, we introduce the abstract
notion of a noncommutative dimension theory by proposing a natural set of
axioms. These axioms are inspired by properties of commutative dimension
theory, and they are for instance satisfied by the real and stable rank, the
decomposition rank and the nuclear dimension.
We add another theory to this list by showing that the topological dimension,
as introduced by Brown and Pedersen, is a noncommutative dimension theory of
type I C*-algebras. We also give estimates of the real and stable rank of a
type I C*-algebra in terms of its topological dimension.Comment: 20 pages; minor correction
Potential benefits of an adaptive forward collision warning system
Forward collision warning (FCW) systems can reduce rear-end vehicle collisions. However, if the presentation of warnings is perceived as mistimed, trust in the system is diminished and drivers become less likely to respond appropriately. In this driving simulator investigation, 45 drivers experienced two FCW systems: a non-adaptive and an adaptive FCW that adjusted the timing of its alarms according to each individual driver’s reaction time. Whilst all drivers benefited in terms of improved safety from both FCW systems, non-aggressive drivers (low sensation seeking, long followers) did not display a preference to the adaptive FCW over its non-adaptive equivalent. Furthermore, there was little evidence to suggest that the non-aggressive drivers’ performance differed with either system. Benefits of the adaptive system were demonstrated for aggressive drivers (high sensation seeking, short followers). Even though both systems reduced their likelihood of a crash to a similar extent, the aggressive drivers rated each FCW more poorly than their non-aggressive contemporaries. However, this group, with their greater risk of involvement in rear-end collisions, reported a preference for the adaptive system as they found it less irritating and stress-inducing. Achieving greater acceptance and hence likely use of a real system is fundamental to good quality FCW design
Dambo Farming In Zimbabwe: Water Management, Cropping and Soil Potentials for Smallholder Farming in the Wetlands.
A Conference Paper on garden irrigation in Zimbabwe.The research described in this report has the potential to improve sustainability of agriculture by reducing farmer reliance on extensive farming systems. The overall aim of the project is to promote the use of small irrigated community gardens to complement
rainfed cropping. In years of good rainfall, these gardens can augment rainfed crop production, reduce the need to crop marginal land and improve nutrition by providing a continuous supply of vegetables during the dry season. In years of drought, such as that now occuring in Southern Africa, there is no rain-fed cropping. Irrigated gardens can provide rural communities with a vital "safety net", providing the only means of food production
Effects of Noisy Oracle on Search Algorithm Complexity
Grover's algorithm provides a quadratic speed-up over classical algorithms
for unstructured database or library searches. This paper examines the
robustness of Grover's search algorithm to a random phase error in the oracle
and analyzes the complexity of the search process as a function of the scaling
of the oracle error with database or library size. Both the discrete- and
continuous-time implementations of the search algorithm are investigated. It is
shown that unless the oracle phase error scales as O(N^(-1/4)), neither the
discrete- nor the continuous-time implementation of Grover's algorithm is
scalably robust to this error in the absence of error correction.Comment: 16 pages, 4 figures, submitted to Phys. Rev.
Parity nonconservation in deuteron photoreactions
We calculate the asymmetries in parity nonconserving deuteron
photodisintegration due to circularly polarized photons gamma+d to n+p with the
photon laboratory energy ranging from the threshold up to 10 MeV and the
radiative capture of thermal polarized neutrons by protons n+p to gamma+d. We
use the leading order electromagnetic Hamiltonian neglecting the smaller
nuclear exchange currents. Comparative calculations are done by using the
Reid93 and Argonne v18 potentials for the strong interaction and the DDH and
FCDH "best" values for the weak couplings in a weak one-meson exchange
potential. A weak NDelta transition potential is used to incorporate also the
Delta(1232)-isobar excitation in the coupled-channels formalism.Comment: 14 pages, 13 figures (18 eps files), LaTeX2
Compartmentalized megakaryocyte death generates functional platelets committed to caspase-independent death
Caspase-directed apoptosis usually fragments cells, releasing nonfunctional, prothrombogenic, membrane-bound apoptotic bodies marked for rapid engulfment by macrophages. Blood platelets are functional anucleate cells generated by specialized fragmentation of their progenitors, megakaryocytes (MKs), but committed to a constitutive caspase-independent death. Constitutive formation of the proplatelet-bearing MK was recently reported to be caspase-dependent, apparently involving mitochondrial release of cytochrome c, a known pro-apoptogenic factor. We extend those studies and report that activation of caspases in MKs, either constitutively or after Fas ligation, yields platelets that are functionally responsive and evade immediate phagocytic clearance, and retain mitochondrial transmembrane potential until constitutive platelet death ensues. Furthermore, the exclusion from the platelet progeny of caspase-9 present in the progenitor accounts for failure of mitochondrial release of cytochrome c to activate caspase-3 during platelet death. Thus, progenitor cell death by apoptosis can result in birth of multiple functional anucleate daughter cells
Experimental observation of nonclassical effects on single-photon detection rates
It is often asserted that quantum effects can be observed in coincidence
detection rates or other correlations, but never in the rate of single-photon
detection. We observe nonclassical interference in a singles rate, thanks to
the intrinsic nonlinearity of photon counters. This is due to a dependence of
the effective detection efficiency on the quantum statistics of the light beam.
Such measurements of detector response to photon pairs promise to shed light on
the microscopic aspects of silicon photodetectors, and on general issues of
quantum measurement and decoherence.Comment: 8 pages, 4 figure
Parity nonconserving cold neutron-parahydrogen interactions
Three pion dominated observables of the parity nonconserving interactions
between the cold neutrons and parahydrogen are calculated. The transversely
polarized neutron spin rotation, unpolarized neutron longitudinal polarization,
and photon-asymmetry of the radiative polarized neutron capture are considered.
For the numerical evaluation of the observables, the strong interactions are
taken into account by the Reid93 potential and the parity nonconserving
interactions by the DDH model along with the two-pion exchange.Comment: 17 pages, 2 figure
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