914 research outputs found
Horizon Problem Remediation via Deformed Phase Space
We investigate the effects of a special kind of dynamical deformation between
the momenta of the scalar field of the Brans-Dicke theory and the scale factor
of the FRW metric. This special choice of deformation includes linearly a
deformation parameter. We trace the deformation footprints in the cosmological
equations of motion when the BD coupling parameter goes to infinity. One class
of the solutions gives a constant scale factor in the late time that confirms
the previous result obtained via another approach in the literature. This
effect can be interpreted as a quantum gravity footprint in the coarse grained
explanation. The another class of the solutions removes the big bang
singularity, and the accelerating expansion region has an infinite temporal
range which overcomes the horizon problem. After this epoch, there is a
graceful exiting by which the universe enters in the radiation dominated era.Comment: 13 pages, 2 figures, to appear in GER
Analysis of the rare semileptonic B_c \rar P(D,D_s) l^{+}l^{-}/\nu\bar{\nu} decays within QCD sum rules
Considering the gluon condensate corrections, the form factors relevant to
the semileptonic rare B_c \rar D,D_s(J^{P}=0^{-}) l^{+}l^{-} with
and B_c \rar D,D_s(J^{P}=0^{-})\nu\bar{\nu} transitions are
calculated in the framework of the three point QCD sum rules. The heavy quark
effective theory limit of the form factors are computed. The branching fraction
of these decays are also evaluated and compared with the predictions of the
relativistic constituent quark model. Analyzing of such type transitions could
give useful information about the strong interactions inside the pseudoscalar
meson and its structure.Comment: 32 Pages, 8 Figures and 6 Table
The Effect of Homogenization Pressure and Stages on the Amounts of Lactic and Acetic Acids of Probiotic Yoghurt
Nowadays the use of probiotic products especially yogurt, due to having wonderful and health properties, has become popular in the world. In this study, the effect of homogenization pressure (100, 150 and 200 bars) and stage (single and two) on the amount of lactic and acetic acids was investigated. Yoghurts were manufactured from low-fat milk treated using high pressure homogenization at 100,150 and 200 bar and at 60°C. The amount of lactic and acetic acids was determined after the days 1, 7, 14 and 21 of storage at 4ºC. The experiments were set up using a completely randomized design. With the increase of pressure and stage of homogenization, the amount of both acids was increased (p<0.01). The greatest amount of lactic and acetic acids during the storage period was observed in the sample homogenized at a pressure of 200 bars and two stages
Semileptonic transition in three--point QCD sum rules and HQET with gluon condensate corrections
Taking into account the gluon condensate contributions, the form factors of
the semileptonic transition with are
calculated in the framework of the three point QCD sum rules. The heavy quark
effective theory limit of the form factors are also computed. The relevant
total decay width as well as the branching ratio are evaluated and compared
with the predictions of the other non-perturbative approaches.Comment: 27 Pages, 4 Figures and 4 Table
Identification and abundance of fungal flora in egg, and larvae of Acipenser persicus in Shahid Beheshti Sturgeon Rearing Center (2007)
Fungal flora in egg, yolk sac larvae and larvae of Acipenser persicus were identified and studied. Totally, 270 specimens from Shahid Beheshti Sturgeon Rearing Center were examined. A heterogeneous solution from samples was prepared and inoculated on culture media SDA+C and CMA+C in lines under sterile conditions. Wet mounts were prepared for the identification of Saprolegnia sp. and the inoculants were cultured on culture media GP containing gentamycin and chloramphenicol. We found Penicillium, Cladosporium, Fusarium, Yeast, Mucor sp., Aspergillus niger and Paecilomuces on egg samples in order of frequency and in water samples we observed Penicillium, Cladosporium, Fusarium, Yeast, Mucor sp., Aspergillus niger, and Paecilomyces. Fungal species identified in yolk sac larvae included Penicilliium sp., Cladosporium sp., Fusarium sp., Alternaria sp., Yeast and in water samples we found Penicillium, Cladosporium, Fusarium, and Yeast, while in larvae we saw Cladosporium sp., Penicilliium sp., Fusarium sp., Alternaria sp., Aspergilus fumigatus, Yeast and Mucor spp. In water samples containing larvae we were able to identify Cladosporium sp., Penicilliium sp., Fusarium sp., Yeast and Aspergilus niger. Fungal species such as Cladosporium sp., Penicillium, Fusarium, Yeast and Saprolegnia were detected in all four sampling mediums. T-test indicated no significant differences in total counts (colonies/2 plates in all samples) in eggs (15.08 ±3.51 colony forming unit; CFU) and in water (15.91± 2.63) samples. However, t-test indicated significant differences in total counts in yolk sac larvae (5.33 ±1.05) and in water (11.77 ±2.39) samples. T-test showed no significant differences in total counts of larvae (32 ±12.46) and water (31.11 ±12.79) samples
Retrieval of Terrestrial Plant Fluorescence based on the in-filling of far-red Fraunhofer lines using SCIAMACHY Observations
Application of Artificial Neural Network (ANN) for Modelling Chromium (VI) Removal from Aqueous Media using Iron Oxide Nanoparticles
Correlation effects in bistability at the nanoscale: steady state and beyond
The possibility of finding multistability in the density and current of an
interacting nanoscale junction coupled to semi-infinite leads is studied at
various levels of approximation. The system is driven out of equilibrium by an
external bias and the non-equilibrium properties are determined by real-time
propagation using both time-dependent density functional theory (TDDFT) and
many-body perturbation theory (MBPT). In TDDFT the exchange-correlation effects
are described within a recently proposed adiabatic local density approximation
(ALDA). In MBPT the electron-electron interaction is incorporated in a
many-body self-energy which is then approximated at the Hartree-Fock (HF),
second-Born (2B) and GW level. Assuming the existence of a steady-state and
solving directly the steady-state equations we find multiple solutions in the
HF approximation and within the ALDA. In these cases we investigate if and how
these solutions can be reached through time evolution and how to reversibly
switch between them. We further show that for the same cases the inclusion of
dynamical correlation effects suppresses bistability.Comment: 13 pages, 12 figure
On the error term in Weyl's law for the Heisenberg manifolds (II)
In this paper we study the mean square of the error term in the Weyl's law of
an irrational -dimensional Heisenberg manifold . An asymptotic formula
is established
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