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A Cell-Centered Adaptive Projection Method for the IncompressibleNavier-Stokes Equations in Three Dimensions
We present a method for computing incompressible viscousflows in three dimensions using block-structured local refinement in bothspace and time. This method uses a projection formulation based on acell-centered approximate projection, combined with the systematic use ofmultilevel elliptic solvers to compute increments in the solutiongenerated at boundaries between refinement levels due to refinement intime. We use an L_0-stable second-order semi-implicit scheme to evaluatethe viscous terms. Results are presentedto demonstrate the accuracy andeffectiveness of this approach
Quenching Capabilities of Long-Chain Carotenoids in Light-Harvesting-2 Complexes from Rhodobacter sphaeroides with an Engineered Carotenoid Synthesis Pathway
Six light-harvesting-2 complexes (LH2) from genetically modified
strains of the purple photosynthetic bacterium Rhodobacter (Rb.) sphaeroides were
studied using static and ultrafast optical methods and resonance Raman
spectroscopy. These strains were engineered to incorporate carotenoids for
which the number of conjugated groups (N = NCC + NCO) varies from 9 to 15.
The Rb. sphaeroides strains incorporate their native carotenoids spheroidene (N =
10) and spheroidenone (N = 11), as well as longer-chain analogues including
spirilloxanthin (N = 13) and diketospirilloxantion (N = 15) normally found in
Rhodospirillum rubrum. Measurements of the properties of the carotenoid first
singlet excited state (S1) in antennas from the Rb. sphaeroides set show that
carotenoid-bacteriochlorophyll a (BChl a) interactions are similar to those in LH2 complexes from various other bacterial species
and thus are not significantly impacted by differences in polypeptide composition. Instead, variations in carotenoid-to-BChl a
energy transfer are primarily regulated by the N-determined energy of the carotenoid S1 excited state, which for long-chain (N â„
13) carotenoids is not involved in energy transfer. Furthermore, the role of the long-chain carotenoids switches from a lightharvesting
supporter (via energy transfer to BChl a) to a quencher of the BChl a S1 excited state B850*. This quenching is
manifested as a substantial (âŒ2-fold) reduction of the B850* lifetime and the B850* fluorescence quantum yield for LH2
housing the longest carotenoids
Determination of nuclear parton distributions
Parametrization of nuclear parton distributions is investigated in the
leading order of alpha_s. The parton distributions are provided at Q^2=1 GeV^2
with a number of parameters, which are determined by a chi^2 analysis of the
data on nuclear structure functions. Quadratic or cubic functional form is
assumed for the initial distributions. Although valence quark distributions in
the medium x region are relatively well determined, the small x distributions
depend slightly on the assumed functional form. It is difficult to determine
the antiquark distributions at medium x and gluon distributions. From the
analysis, we propose parton distributions at Q^2=1 GeV^2 for nuclei from
deuteron to heavy ones with the mass number A~208. They are provided either
analytical expressions or computer subroutines for practical usage. Our studies
should be important for understanding the physics mechanism of the nuclear
modification and also for applications to heavy-ion reactions. This kind of
nuclear parametrization should also affect existing parametrization studies in
the nucleon because "nuclear" data are partially used for obtaining the optimum
distributions in the "nucleon".Comment: 16 pages, REVTeX4b5, revtex4.cls, url.sty, natbib.sty, 10pt.rtx,
aps.rtx, revsymb.sty, 21 eps figures. Submitted for publication. Computer
codes for the nuclear parton distributions could be obtained from
http://www-hs.phys.saga-u.ac.jp Email: [email protected]
Creating patient value in glaucoma care
Purpose: The purpose of this paper is to explore in a specific hospital care process the applicability
in practice of the theories of quality costing and value chains.
Design/methodology/approach: In a retrospective case study an in-depth evaluation of the use of
a quality cost mode
Quantum Maxwell-Bloch equations for spatially inhomogeneous semiconductor lasers
We present quantum Maxwell-Bloch equations (QMBE) for spatially inhomogeneous
semiconductor laser devices. The QMBE are derived from fully quantum mechanical
operator dynamics describing the interaction of the light field with the
quantum states of the electrons and the holes near the band gap. By taking into
account field-field correlations and field-dipole correlations, the QMBE
include quantum noise effects which cause spontaneous emission and amplified
spontaneous emission. In particular, the source of spontaneous emission is
obtained by factorizing the dipole-dipole correlations into a product of
electron and hole densities. The QMBE are formulated for general devices, for
edge emitting lasers and for vertical cavity surface emitting lasers, providing
a starting point for the detailed analysis of spatial coherence in the near
field and far field patterns of such laser diodes. Analytical expressions are
given for the spectra of gain and spontaneous emission described by the QMBE.
These results are applied to the case of a broad area laser, for which the
frequency and carrier density dependent spontaneous emission factor beta and
the evolution of the far field pattern near threshold are derived.Comment: 22 pages RevTex and 7 figures, submitted to Phys.Rev.A, revisions in
abstract and in the discussion of temporal coherenc
Phenomenological Tests of Supersymmetric A_4 Family Symmetry Model of Neutrino Mass
Recently Babu, Ma and Valle proposed a model of quark and lepton mixing based
on symmetry. Within this model the lepton and slepton mixings are
intimately related. We perform a numerical study in order to derive the slepton
masses and mixings in agreement with present data from neutrino physics. We
show that, starting from three-fold degeneracy of the neutrino masses at a high
energy scale, a viable low energy neutrino mass matrix can indeed be obtained
in agreement with constraints on lepton flavour violating
and decays. The resulting slepton spectrum must necessarily
include at least one mass below 200 GeV which can be produced at the LHC. The
predictions for the absolute Majorana neutrino mass scale eV
ensure that the model will be tested by future cosmological tests and
searches.
Rates for lepton flavour violating processes
in the range of sensitivity of current
experiments are typical in the model, with BR(\mu \to e \gamma) \gsim
10^{-15} and the lower bound BR. To first
approximation, the model leads to maximal leptonic CP violation in neutrino
oscillations.Comment: 23 pages, 7 figure
Charged-Lepton-Flavour Violation in the CMSSM in View of the Muon Anomalous Magnetic Moment
We use the BNL E821 measurement of g - 2, the anomalous magnetic moment of
the muon, to normalize, within a supersymmetric GUT framework, constrained MSSM
(CMSSM) predictions for processes that violate charged-lepton flavour
conservation, including mu to e gamma, mu to e conversion and K^0_L to mu e. We
illustrate our analysis with two examples of lepton mass matrix textures
motivated by data on neutrino oscillations. We find that mu to e gamma may well
occur at a rate within one or two (two or three) orders of magnitude of the
present experimental upper limit if g - 2 is within the one- (two-)standard
deviation range indicated by E821. We also find that mu to e conversion is
likely to occur at rate measurable by MECO, and there is a chance that K^0_L to
mu e may be observable in an experiment using an intense proton source.Comment: 14 pages, 3 eps figure
Do the Unidentified EGRET Sources Trace Annihilating Dark Matter in the Local Group?
In a cold dark matter (CDM) framework of structure formation, the dark matter
haloes around galaxies assemble through successive mergers with smaller haloes.
This merging process is not completely efficient, and hundreds of surviving
halo cores, or {\it subhaloes}, are expected to remain in orbit within the halo
of a galaxy like the Milky Way. While the dozen visible satellites of the Milky
Way may trace some of these subhaloes, the majority are currently undetected. A
large number of high-velocity clouds (HVCs) of neutral hydrogen {\it are}
observed around the Milky Way, and it is plausible that some of the HVCs may
trace subhaloes undetected in the optical. Confirming the existence of
concentrations of dark matter associated with even a few of the HVCs would
represent a dramatic step forward in our attempts to understand the nature of
dark matter. Supersymmetric (SUSY) extensions of the Standard Model of particle
physics currently suggest neutralinos as a natural well-motivated candidate for
the non-baryonic dark matter of the universe. If this is indeed the case, then
it may be possible to detect dark matter indirectly as it annihilates into
neutrinos, photons or positrons. In particular, the centres of subhaloes might
show up as point sources in gamma-ray observations. In this work we consider
the possibility that some of the unidentified EGRET -ray sources trace
annihilating neutralino dark matter in the dark substructure of the Local
Group. We compare the observed positions and fluxes of both the unidentified
EGRET sources and the HVCs with the positions and fluxes predicted by a model
of halo substructure, to determine to what extent any of these three
populations could be associated.Comment: 12 Pages, 4 figures, to appear in a special issue of ApSS. Presented
at "The Multiwavelength Approach to Unidentified Gamma-Ray Sources" (Hong
Kong, June 1 - 4, 2004; Conference organizers: K.S. Cheng and G.E. Romero
Quantum electromagnetic field in a three dimensional oscillating cavity
We compute the photon creation inside a perfectly conducting, three
dimensional oscillating cavity, taking the polarization of the electromagnetic
field into account. As the boundary conditions for this field are both of
Dirichlet and (generalized) Neumann type, we analyze as a preliminary step the
dynamical Casimir effect for a scalar field satisfying generalized Neumann
boundary conditions. We show that particle production is enhanced with respect
to the case of Dirichlet boundary conditions. Then we consider the transverse
electric and transverse magnetic polarizations of the electromagnetic field.
For resonant frequencies, the total number of photons grows exponentially in
time for both polarizations, the rate being greater for transverse magnetic
modes.Comment: 11 pages, 1 figur
Setting ART initiation targets in response to changing guidelines: The importance of addressing both steady-state and backlog
BACKGROUND: Target setting is useful in planning, assessing and improving antiretroviral treatment (ART) programmes. In the past 4 years, the ART initiation environment has been transformed due to the change in eligibility criteria (starting ART at a CD4+ count <350 cells/”lv. <200 cells/”l) and the roll-out of nurse-initiated management of ART. OBJECTIVE: To describe and illustrate the use of a target-setting model for estimating district-based targets in the era of an expanding ART programme and changing CD4+ count thresholds for ART initiation. METHOD: Using previously described models and data for annual new HIV infections, we estimated both steady-state need for ART initiation and backlog in a North West Province district, accounting for the shift in eligibility. Comparison of actual v. targeted ART initiations was undertaken. The change in CD4+ count threshold adds a once-off group of newly eligible patients to the pool requiring ART - the backlog. The steady-state remains unchanged as it is determined by the annual rate of new HIV infections in previous years. RESULTS: The steady-state need for the district was 639 initiations/month, and the backlog was ~15 388 patients. After the shift in eligibility in September 2011, the steady-state target was exceeded over several months with some backlog addressed. Of the total backlog for this district, 72% remains to be cleared. CONCLUSION: South Africa has two pools of patients who need ART: the steady-state of HIV-infected patients entering the programme each year, determined by historical infection rates; and the backlog created by the shift in eligibility. The healthcare system needs to build long-term capacity to meet the steady-state need for ART and additional capacity to address the backlog
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