Energy-Momentum Localization for a Space-Time Geometry Exterior to a Black Hole in the Brane World

In general relativity one of the most fundamental issues consists in defining a generally acceptable definition for the energy-momentum density. As a consequence, many coordinate-dependent definitions have been presented, whereby some of them utilize appropriate energy-momentum complexes. We investigate the energy-momentum distribution for a metric exterior to a spherically symmetric black hole in the brane world by applying the Landau-Lifshitz and Weinberg prescriptions. In both the aforesaid prescriptions, the energy thus obtained depends on the radial coordinate, the mass of the black hole and a parameter $\lambda_{0}$, while all the momenta are found to be zero. It is shown that for a special value of the parameter $\lambda_{0}$, the Schwarzschild space-time geometry is recovered. Some particular and limiting cases are also discussed.Comment: 10 pages, sections 1 and 3 slightly modified, references modified and adde

Hidden vector dark matter

We show that dark matter could be made of massive gauge bosons whose stability doesn't require to impose by hand any discrete or global symmetry. Stability of gauge bosons can be guaranteed by the custodial symmetry associated to the gauge symmetry and particle content of the model. The particle content we consider to this end is based on a hidden sector made of a vector multiplet associated to a non-abelian gauge group and of a scalar multiplet charged under this gauge group. The hidden sector interacts with the Standard Model particles through the Higgs portal quartic scalar interaction in such a way that the gauge bosons behave as thermal WIMPS. This can lead easily to the observed dark matter relic density in agreement with the other various constraints, and can be tested experimentally in a large fraction of the parameter space. In this model the dark matter direct detection rate and the annihilation cross section can decouple if the Higgs portal interaction is weak.Comment: 13 pages, 7 figures, JHEP published version (2009) + update of section 7 (reference to arXiv:0912.4496

Gallstone Disease After Laparoscopic Sleeve Gastrectomy in an Asian Population—What Proportion of Gallstones Actually Becomes Symptomatic?

10.1007/s11695-017-2657-yObesity Surgery2792419-2423OBSU

Anaesthesia considerations and techniques for Pressurised IntraPeritoneal Aerosol Chemotherapy (PIPAC)

10.1515/pp-2019-0013Pleura and Peritoneum542019001

Dimensioning and location planning for wireless networks under multi-level cooperative relaying

This paper studies the problem of network dimensioning and location planning in multi-hop wireless networks. A key technology of wireless multi-level cooperative relaying (CR) is incorporated, which has been recognized as an effective design paradigm for achieving throughput enhancement. A mathematical formulation is presented to capture the nature of the problem, and characterize the behavior of multi-level CR. The tasks of dimensioning, relay placement, relay allocation, and relay sequence design have been considered in a unified optimization framework. The formulation is a nonlinear integer program. To avoid the intractable computation complexity in solution, an efficient two-phase algorithm is developed. We conduct a series of case studies to verify the proposed algorithm, in which the results demonstrate the efficiency of our proposed algorithm and the significant benefits in terms of deployment cost reduction under multi-level CR. © IFIP International Federation for Information Processing 2009.link_to_subscribed_fulltex

Cloning of rat telomerase catalytic subunit functional domains, reconstitution of telomerase activity and enzymatic profile of pig and chicken tissues

10.1016/S0024-3205(03)00670-2Life Sciences73212749-2760LIFS

Palaeoproterozoic ice houses and the evolution of oxygen-mediating enzymes: the case for a late origin of photosystem II

Two major geological problems regarding the origin of oxygenic photosynthesis are (i) identifying a source of oxygen pre-dating the biological oxygen production and capable of driving the evolution of oxygen tolerance, and (ii) determining when oxygenic photosynthesis evolved. One solution to the first problem is the accumulation of photochemically produced H2O2 at the surface of the glaciers and its subsequent incorporation into ice. Melting at the glacier base would release H2O2, which interacts with seawater to produce O2 in an environment shielded from the lethal levels of ultraviolet radiation needed to produce H2O2. Answers to the second problem are controversial and range from 3.8 to 2.2 Gyr ago. A sceptical view, based on the metals that have the redox potentials close to oxygen, argues for the late end of the range. The preponderance of geological evidence suggests little or no oxygen in the Late Archaean atmosphere (less than 1 ppm). The main piece of evidence for an earlier evolution of oxygenic photosynthesis comes from lipid biomarkers. Recent work, however, has shown that 2-methylhopanes, once thought to be unique biomarkers for cyanobacteria, are also produced anaerobically in significant quantities by at least two strains of anoxygenic phototrophs. Sterane biomarkers provide the strongest evidence for a date 2.7 Gyr ago or above, and could also be explained by the common evolutionary pattern of replacing anaerobic enzymes with oxygen-dependent ones. Although no anaerobic sterol synthesis pathway has been identified in the modern biosphere, enzymes that perform the necessary chemistry do exist. This analysis suggests that oxygenic photosynthesis could have evolved close in geological time to the Makganyene Snowball Earth Event and argues for a causal link between the two