Brans-Dicke Theory as a Unified Model for Dark Matter - Dark Energy

The Brans-Dicke (BD) theory of gravity is taken as a possible theory of k-essence coupled to gravity. It then has been realized that the BD scalar field does indeed play a role of a k-essence, but in a very unique way which distinguishes it from other k-essence fields studied in the literature. That is, first in the BD scalar field-dominated era when the contribution from this k-essence overwhelms those from other types of matter, the BD theory predicts the emergence of a yet-unknown {\it zero acceleration} epoch which is an intermediate stage acting as a ``crossing bridge'' between the decelerating matter-dominated era and the accelerating phase. Upon realizing this, next, closer study of the effects of this k-essence on the evolutionary behavior of the matter-dominated and the accelerating eras has been performed. The result of the study indicates that the BD scalar field appears to interpolate {\it smoothly} between these two late-time stages by speeding up the expansion rate of the matter-dominated era somewhat while slowing down that of the accelerating phase to some degree. Thus with the newly found BD scalar field-dominated era in between these two, the late-time of the universe evolution appears to be mixed sequence of the three stages.Comment: 25 pages, Mon. Not. R. Astron. Soc.(MNRAS), in pres

A natural solution to the μ\mu-problem in dynamical supergravity model

The Higgs mixing term coefficient $\mu$ is calculated in the supersymmetric theory which possesses a non-anomalous $U(1)_{R}$ symmetry in the limit of global supersymmetry. In this model, supersymmetry is assumed to be broken by gaugino condensation in the hidden sector when the supergravity effects are turned on. The soft breaking terms in the visible sector and the $\mu$ term of order the weak scale are produced in a simple manner.Comment: 6 pages, Latex, accepted for publication in Phys.Rev.

Phytochemical Constituents and Analgesic Activity of Ethyl Acetate Fraction of Punicagranatum L (Punicaceae)

Purpose: To investigate the active fraction of pomegranate fruit extract and screen it for analgesic activity.Methods: The analgesic activity of pomegranate ethyl acetate fraction (EtOAc) was examined using three models of pain: writhing, hot tail flick and plantar tests. EtOAc was administered by oral gavage in doses of 100, 150 and 200 mg/kg, p.o., for all the tests and compared to aspirin (100 mg/kg, p.o.) which was used as standard drug. Phytochemical studies of EtOAc were carried out by high performance liquid chromatography (HPLC) with ultraviolet (UV) detection and mass spectrometry (MS).Results: In the writhing test, the index of pain inhibition (IPI) was 41 % for EtOAc (200 mg/kg, p.o.) and 56 % for aspirin. In the hot tail flick test, EtOAc (200 mg/kg, p.o.) showed analgesia reaching its peak at 60 min with maximum possible analgesia (MPA) of 30.5 %, compared with 43.8 % for aspirin. Plantar test showed that pain was reduced by EtOAc in a dose-dependent manner and compared well with aspirin at 100 mg/kg, p.o., dose. The 200 mg/kg dose showed the highest effect, prolonging withdrawal latency in the left hind paw to 11.9 ± 0.3 compared to aspirin with 13.4 ± 0.2 (p < 0.001). HPLC analysis of EtOAc revealed the presence of gallic acid, ellagic acid and punicalagins A & B. Confirmation of their structures was achieved by mass spectroscopy.Conclusion: EtOAc has a central and peripheral analgesic effect that is most likely due to the presence of gallic acid and ellagic acid.Keywords: Analgesia, Pomegranate, Gallic acid, Ellagic acid, Punicalagins, Phytochemical constituent