595 research outputs found
Quasi-local Energy for Spherically Symmetric Spacetimes
We present two complementary approaches for determining the reference for the
covariant Hamiltonian boundary term quasi-local energy and test them on
spherically symmetric spacetimes. On the one hand, we isometrically match the
2-surface and extremize the energy. This can be done in two ways, which we call
programs I (without constraint) and II (with additional constraints). On the
other hand, we match the orthonormal 4-frames of the dynamic and the reference
spacetimes. Then, if we further specify the observer by requiring the reference
displacement to be the timelike Killing vector of the reference, the result is
the same as program I, and the energy can be positive, zero, or even negative.
If, instead, we require that the Lie derivatives of the two-area along the
displacement vector in both the dynamic and reference spacetimes to be the
same, the result is the same as program II, and it satisfies the usual
criteria: the energies are non-negative and vanish only for Minkowski (or
anti-de Sitter) spacetime.Comment: 16 pages, no figure
A Note on Acceleration from Product Space Compactification
We study compactifications of Einstein gravity on product spaces in vacuum
and their acceleration phases. Scalar potentials for the dimensionally reduced
effective theory are found to be of exponential form and exact solutions are
obtained for a class of product spaces. The inflation in our solutions is not
sufficient for the early universe. We comment on the possibility of obtaining
sufficient inflation by compactification in general.Comment: 19 pages, 6 figures, v2: further comments and references added, v3:
typos fixe
A marker of glutathione S-transferase-mediated resistance to insecticides is associated with higher Plasmodium infection in the African malaria vector Anopheles funestus
Metabolic resistance to insecticides is threatening malaria control in Africa. However, the extent to which it impacts malaria transmission remains unclear. Here, we investigated the association between a marker of glutathione S-transferase mediated metabolic resistance and Plasmodium infection in field population of Anopheles funestus s.s. in comparison to the A296S-RDL target site mutation. The 119F-GSTe2 resistant allele was present in southern (Obout) (56%) and central (Mibellon) (25%) regions of Cameroon whereas the 296S-RDL resistant allele was detected at 98.5% and 15% respectively. The whole mosquito Plasmodium and sporozoite infection rates were 57% and 14.8% respectively in Obout (n = 508) and 19.7% and 5% in Mibellon (n = 360). No association was found between L119F-GSTe2 genotypes and whole mosquito infection status. However, when analyzing oocyst and sporozoite infection rates separately, the resistant homozygote 119F/F genotype was significantly more associated with Plasmodium infection in Obout than both heterozygote (OR = 2.5; P = 0.012) and homozygote susceptible (L/L119) genotypes (OR = 2.10; P = 0.013). In contrast, homozygote RDL susceptible mosquitoes (A/A296) were associated more frequently with Plasmodium infection than other genotypes (OR = 4; P = 0.03). No additive interaction was found between L119F and A296S. Sequencing of the GSTe2 gene showed no association between the polymorphism of this gene and Plasmodium infection. Glutathione S-transferase metabolic resistance is potentially increasing the vectorial capacity of resistant An. funestus mosquitoes. This could result in a possible exacerbation of malaria transmission in areas of high GSTe2-based metabolic resistance to insecticides
Hyperbolic Space Cosmologies
We present a systematic study of accelerating cosmologies obtained from
M/string theory compactifications of hyperbolic spaces with time-varying
volume. A set of vacuum solutions where the internal space is a product of
hyperbolic manifolds is found to give qualitatively the same accelerating
four-dimensional FLRW universe behavior as a single hyperbolic space. We also
examine the possibility that our universe is a hyperbolic space and provide
exact Milne type solutions, as well as intersecting S-brane solutions. When
both the usual 4D spacetime and the m-dimensional internal space are
hyperbolic, we find eternally accelerating cosmologies for , with and
without form field backgrounds. In particular, the effective potential for a
magnetic field background in the large 3 dimensions is positive definite with a
local minimum and thus enhances the eternally accelerating expansion.Comment: 33 pages, 2 figures; v2 refs added; v3 minor change in text, JHEP
versio
Notes on the algebraic curves in (p,q) minimal string theory
Loop amplitudes in (p,q) minimal string theory are studied in terms of the
continuum string field theory based on the free fermion realization of the KP
hierarchy. We derive the Schwinger-Dyson equations for FZZT disk amplitudes
directly from the W_{1+\infty} constraints in the string field formulation and
give explicitly the algebraic curves of disk amplitudes for general
backgrounds. We further give annulus amplitudes of FZZT-FZZT, FZZT-ZZ and ZZ-ZZ
branes, generalizing our previous D-instanton calculus from the minimal unitary
series (p,p+1) to general (p,q) series. We also give a detailed explanation on
the equivalence between the Douglas equation and the string field theory based
on the KP hierarchy under the W_{1+\infty} constraints.Comment: 61 pages, 1 figure, section 2.5 and Appendix B added, references
added, final version to appear in JHE
Comments on the Quark Content of the Scalar Meson
Based on the measurements of we determine, in
a model independent way, the allowed content in the scalar meson
. We find that, on the one hand, if this isoscalar resonance is a
pure state [ , a very
large -annihilation term will be needed to accommodate . On the other hand, the component of
should be small enough to avoid excessive induced
from the external -emission. Measurement of production in the
decay will be useful to test the above picture. For the
decay which is kinematically barely or even not
allowed, depending on the mass of , we find that the finite width
effect of plays a crucial role on the resonant three-body decay
.Comment: 12 pages, 2 figure
Measuring the Relative Strong Phase in and Decays
In a recently suggested method for measuring the weak phase in
decays, the relative strong phase in and decays (equivalently, in and \od \to K^{*+} K^-) plays a role. It is shown how a study of
the Dalitz plot in can yield information on this phase,
and the size of the data sample which would give a useful measurement is
estimated.Comment: 13 pages, latex, 5 figures, submitted to Phys. Rev. D. Appendix and
some text on additional resonant contributions adde
Using untagged B^0 -> D K_S to determine gamma
It is shown that the weak phase gamma=arg(-V_{ud}V^*_{ub}V_{cb}V_{cd}^*) can
be determined using only untagged decays B/Bbar--> D K_S. In order to reduce
the uncertainty in gamma, we suggest combining information from B^{+-}-->
DK^{+-} and from untagged B^0 decays, where the D meson is observed in common
decay modes. Theoretical assumptions, which may further reduce the statistical
error, are also discussed.Comment: 18 pages, same as published versio
Cosmic Microwave Background Observables of Small Field Models of Inflation
We construct a class of single small field models of inflation that can
predict, contrary to popular wisdom, an observable gravitational wave signal in
the cosmic microwave background anisotropies. The spectral index, its running,
the tensor to scalar ratio and the number of e-folds can cover all the
parameter space currently allowed by cosmological observations. A unique
feature of models in this class is their ability to predict a negative spectral
index running in accordance with recent cosmic microwave background
observations. We discuss the new class of models from an effective field theory
perspective and show that if the dimensionless trilinear coupling is small, as
required for consistency, then the observed spectral index running implies a
high scale of inflation and hence an observable gravitational wave signal. All
the models share a distinct prediction of higher power at smaller scales,
making them easy targets for detection.Comment: 13 pages, 3 figures, added numerical analysis and discussion on the
properties of the spectra. Version to be published in JCA
A Phenomenological Analysis of Gluon Mass Effects in Inclusive Radiative Decays of the and $\Upsilon
The shapes of the inclusive photon spectra in the processes \Jp \to \gamma
X and \Up \to \gamma X have been analysed using all available experimental
data.
Relativistic, higher order QCD and gluon mass corrections were taken into
account in the fitted functions. Only on including the gluon mass corrections,
were consistent and acceptable fits obtained. Values of
GeV and GeV were found for the
effective gluon masses (corresponding to Born level diagrams) for the \Jp and
\Up respectively. The width ratios \Gamma(V \to {\rm hadrons})/\Gamma(V \to
\gamma+ {\rm hadrons}) V=\Jp, \Up were used to determine and . Values consistent with the current world
average were obtained only when gluon mass correction factors,
calculated using the fitted values of the effective gluon mass, were applied. A
gluon mass GeV, as suggested with these results, is consistent with
previous analytical theoretical calculations and independent phenomenological
estimates, as well as with a recent, more accurate, lattice calculation of the
gluon propagator in the infra-red region.Comment: 50 pages, 11 figures, 15 table
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