442 research outputs found
Localization of Bulk Form Fields on Dilatonic Domain Walls
We study the localization properties of bulk form potentials on dilatonic
domain walls. We find that bulk form potentials of any ranks can be localized
as form potentials of the same ranks or one lower ranks, for any values of the
dilaton coupling parameter. For large enough values of the dilaton coupling
parameter, bulk form potentials of any ranks can be localized as form
potentials of both the same ranks and one lower ranks.Comment: 9 pages, LaTeX, reference adde
Towards the entropy of gravity time-dependent models via the Cardy-Verlinde formula
For models with several time-dependent components generalized entropies can
be defined. This is shown for the Bianchi type IX model. We first derive the
Cardy-Verlinde formula under the assumption that the first law of
thermodynamics is valid. This leads to an explicit expression of the total
entropy associated with this type of universes. Assuming the validity of the
Cardy entropy formula, we obtain expressions for the corresponding Bekenstein,
Bekenstein-Hawking and Hubble entropies. We discuss the validity of the
Cardy-Verlinde formula and possible extensions of the outlined procedure to
other time-dependent models.Comment: 13 page
Supergravity, Non-Conformal Field Theories and Brane-Worlds
We consider the supergravity dual descriptions of non-conformal super
Yang-Mills theories realized on the world-volume of Dp-branes. We use the dual
description to compute stress-energy tensor and current correlators. We apply
the results to the study of dilatonic brane-worlds described by non-conformal
field theories coupled to gravity. We find that brane-worlds based on D4 and D5
branes exhibit a localization of gauge and gravitational fields. We calculate
the corrections to the Newton and Coulomb laws in these theories.Comment: 24 pages, Latex, 2 figure
Simple quantum cosmology: Vacuum energy and initial state
A static non-singular 10-dimensional closed Friedmann universe of Planck
size, filled with a perfect fluid with an equation of state with w = -2/3, can
arise spontaneously by a quantum fluctuation from nothing in 11-dimensional
spacetime. A quantum transition from this state can initiate the inflationary
quantum cosmology outlined in Ref. 2 [General Relativity and Gravitation 33,
1415, 2001 - gr-qc/0103021]. With no fine-tuning, that cosmology predicts about
60 e-folds of inflation and a vacuum energy density depending only on the
number of extra space dimensions (seven), G, h, c and the ratio between the
strength of gravity and the strength of the strong force. The fraction of the
total energy in the universe represented by this vacuum energy depends on the
Hubble constant. Hubble constant estimates from WMAP, SDSS, the Hubble Key
Project and Sunyaev-Zeldovich and X-ray flux measurements range from 60 to 72
km/(Mpc sec). With a mid-range Hubble constant of 65 km/(Mpc sec), the model in
Ref. 2 predicts Omega-sub-Lambda = 0.7Comment: To be published in General Relativity and Gravitation, Vol. 37, May
2005. 5 pages, no figure
Life-fertility tables of Bracon hebetor Say (Hymenoptera: Braconidae) reared on Heliocheilus albipunctella de Joannis (Lepidoptera: Noctuidae).
Life-fertility tables were described for Bracon hebetor Say (Hymenoptera: Braconidae) developing on the millet head caterpillar (MHC), Heliocheilus albipunctella de Joannis (Lepidoptera: Noctuidae). Mated B. hebetor females lived an average of 24.7 days, oviposited ca. 22 days, and produced, 173.7 adult progeny with a 1:1 sex ratio. The estimated innate capacity of increase (r) and net reproductive rate (R0) were 0.26 and 86.5, respectively. The mean generation time was 1 days
Population dynamics and parasitism of Coniesta(= Haimbachia) ignefusalis, Sesamia calamistis, and Heliocheilus albipunctella in millet monoculture
Studies were conducted in Niger in 1986 and 1987 on the population dynamics and parasitism of the millet stem borer, Coniesta (=Haimbachia) ignefusalis (Hampson) (Lepidoptera:Pyralidae), Sesamia calamistis Hampson, and the millet head caterpillar, Heliocheilus albipunctella de Joannis (Lepidoptera:Noctuidae). Planting dates were assessed for effects on population densities of C. ignefusalis and H. albipunctella. Population densities of C. ignefusalis were not reduced by adjusting millet planting dates, but were affected by millet growth stage. Platytelenomus sp. (Hymenoptera:Scelionidae) was the most common parasite of C. ignefusalis on millet. Parasitism of C. ignefusalis larvae and pupae was rare. Sesamia calamistis was a minor pest of millet in Niger, and was rarely parasitized. Population densities of H. albipunctella were reduced by delaying millet planting dates. Bracon hebetor (Hymenoptera:Braconidae) was the most common parasite of H. albipunctella
Assessment of yield loss due to the millet head miner, Heliocheilus albipunctella (Lepidoptera: Noctuidae) using a damage rating scale and regression analysis in Niger
Linear equations for five pearl millet (Pennisetum glaucum) varieties were established for yield losses due to damage by the noctuid Heliocheilus albipunctella, using a panicle damage rating scale. A very high positive correlation (r0.90; P=0.001) was found between damage rating and percentage yield loss, and also between observed and predicted yield loss. The low percentage absolute deviation (% ad) and deviation ratios (dr) between observed and predicted yield loss demonstrated the reliability of the damage rating scale, and the established yield loss equations. In addition, the damage rating on farmers'' fields by farmers and a team of technicians showed that the method can be used for quick on-farm assessment of yield loss by extension agents and farmers. In four farmers'' fields, the estimated yield loss for the local variety (Sadore local) ranged from 11.7 to 41.9%. Implications of the use of the method for future crop loss assessment in pearl millet are presented and discussed
Habitat site selection, crop damage and oviposition preference by Contesta ( = Haimbachia) ignefusalis (Lepidoptera: Pyralidae)
Studies were conducted during 1986â1988 to investigate habitat site selection, evaluate damage, and study the oviposition preference of Coniesta ignefusalis (Hampson) on natural and artificial substrates to improve rearing and management techniques. Millet grain weight was negatively correlated with numbers of stemâborer larval exit and entrance holes. Numbers of diapausing larvae and borer larval holes were positively correlated with the location of internodes on millet stems. Survival of C. ignefusalisin dry millet stems is significant when stems were stacked as practised by farmers. C. ignefusalistemaie oviposition occurred mostly within leaf sheaths of green millet plants, rarely on green or dry leaves, and seldom on dry millet stems. Paper substrates rarely received eggs when offered to females in association with green millet stems with attached leaf sheath. The implications of our findings for IPM of C. ignefusalis are discussed
Origin of FRW cosmology in slow-roll inflation from noncompact Kaluza-Klein theory
Using a recently introduced formalism we discuss slow-roll inflaton from
Kaluza-Klein theory without the cylinder condition. In particular, some
examples corresponding to polynomic and hyperbolic -potentials are
studied. We find that the evolution of the fifth coordinate should be
determinant for both, the evolution of the early inflationary universe and the
quantum fluctuations.Comment: (final version) to be published in EPJ
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