Rotating black hole in extended Chern-Simons modified gravity

We investigate a slowly rotating black hole in four-dimensional extended Chern-Simons modified gravity. We obtain an approximate solution that reduces to the Kerr solution when a coupling constant vanishes. The Chern-Simons correction effectively reduces the frame-dragging effect around a black hole in comparison with that of the Kerr solution.Comment: 9 pages, 1 figure, to appear in Progress of Theoretical Physics, typos correcte

Does a black hole rotate in Chern-Simons modified gravity?

Rotating black hole solutions in the (3+1)-dimensional Chern-Simons modified gravity theory are discussed by taking account of perturbation around the Schwarzschild solution. The zenith-angle dependence of a metric function related to the frame-dragging effect is determined from a constraint equation independently of a choice of the embedding coordinate. We find that at least within the framework of the first-order perturbation method, the black hole cannot rotate for finite black hole mass if the embedding coordinate is taken to be a timelike vector. However, the rotation can be permitted in the limit of $M/r \to 0$ (where $M$ is the black hole mass and $r$ is the radius). For a spacelike vector, the rotation can also be permitted for any value of the black hole mass.Comment: 4 pages, Accepted for publication in Phys. Rev.

Perceptions of caregivers about health and nutritional problems and feeding practices of infants: a qualitative study on exclusive breast-feeding in Kwale, Kenya

BACKGROUND: Despite the significant positive effect of exclusive breast-feeding on child health, only 32% of children under 6 months old were exclusively breast-fed in Kenya in 2008. The aim of this study was to explore perceptions and feeding practices of caregivers of children under 6 months old with special attention to the caregivers’ indigenous knowledge, perceptions about the health and nutritional problems of their infants, and care-seeking behaviors that affect feeding practices. METHODS: The study was exploratory and used an inductive approach. In all, 32 key informants, including mothers, mothers-in-law, and traditional healers, were interviewed in-depth. The number of participants in free-listing of perceived health problems of babies, in ranking of the perceived severity of these health problems, and in free-listing of food and drink given to children under 6 months old were 29, 28, and 32, respectively. Additionally, 28 babies under 6 months old were observed at home with regard to feeding practices. Data obtained using these methods were triangulated to formulate an ethnomedical explanatory model for mothers who do not practice exclusive breast-feeding. RESULTS: The informants stated that various types of food, drink, and medicine were given to infants under 6 months old. Direct observation also confirmed that 2- to 3-month-old babies were given porridge, water, juice, herbal medicine, and over-the-counter medicine. Mothers’ perceptions of insufficient breast milk production and a lack of proper knowledge about the value of breast milk were identified in key informant interviews, free-listing, and ranking as important factors associating with the use of food and drink other than breast milk; in addition, perceived ill health of babies appears to be associated with suboptimal practice of exclusive breast-feeding. Caregivers used various folk and popular medicines from the drugstore, their own backyard or garden, and traditional healers so that the mother or child would not be exposed to perceived risks during the vulnerable period after birth. CONCLUSIONS: Mothers should be advised during their antenatal and postnatal care about exclusive breast-feeding. This should be done not as a single vertical message, but in relation to their concerns about the health and nutritional problems of their babies

Discovery of parity-violating Majorana fermions in a chiral superconductor Sr2RuO4

We found parity-violating Majorana fermions in a chiral superconductor Sr2RuO4. The current-voltage curves show an anomalous behavior: The induced voltage is an even function of the bias current. The magnetic field dependent results suggest the excitation of the Majorana fermions along the closed chiral edge current of the single domain under bias current. We also discuss the relationship between a change of the chirality and spontaneous magnetization of the single domain Sr2RuO4

Development of ion beam figuring system with electrostatic deflection for ultraprecise X-ray reflective optics

We developed an ion beam figuring system that utilizes electrostatic deflection. The system can produce an arbitrary shape by deterministically scanning the ion beam. The scan of the ion beam, which can be precisely controlled using only an electrical signal, enables us to avoid degradation of the mirror shape caused by imperfect acceleration or deceleration of a mechanically scanning stage. Additionally, this surface figuring method can easily be combined with X-ray metrology because the workpiece remains fixed during the figuring. We evaluated the figuring accuracy of the system by fabricating a plano-elliptical mirror for X-ray focusing. A mirror with a shape error of 1.4 nm root mean square (RMS) with a maximum removal depth of 992 nm, which corresponds to figuring accuracy of 0.14% RMS, was achieved. After the second shape corrections, an elliptical shape with a shape error of approximately 1 nm peak-to-valley, 0.48 nm RMS could be fabricated. Then, the mirror surface was smoothed by a low-energy ion beam. Consequently, a micro-roughness of 0.117 nm RMS, measured by atomic force microscopy, was achieved over an area of 1 × 1 μm2.Jumpei Yamada, Satoshi Matsuyama, Yasuhisa Sano, and Kazuto Yamauchi, "Development of ion beam figuring system with electrostatic deflection for ultraprecise X-ray reflective optics", Review of Scientific Instruments 86, 093103 (2015) https://doi.org/10.1063/1.4929323

Flat rotation curves in Chern-Simons modified gravity

We investigate the spacetime of a slowly rotating black hole in the Chern-Simons modified gravity. The long range feature of frame-dragging effect under the Chern-Simon gravity well explains the flat rotation curves of galaxies which is a central evidence of dark matter. Our solution provides a different scenario of rotating space from Goedel's solution.Comment: 4 pages, Accepted for publication in Phys. Rev.

The Nakano-Nishijima-Gell-Mann Formula From Discrete Galois Fields

The well known Nakano-Nishijima-Gell-Mann (NNG) formula relates certain quantum numbers of elementary particles to their charge number. This equation, which phenomenologically introduces the quantum numbers $I_z$ (isospin), $S$ (strangeness), etc., is constructed using group theory with real numbers $\mathbb{R}$. But, using a discrete Galois field $\mathbb{F}_p$ instead of $\mathbb{R}$ and assuring the fundamental invariance laws such as unitarity, Lorentz invariance, and gauge invariance, we derive the NNG formula deductively from Meson (two quarks) and Baryon (three quarks) representations in a unified way. Moreover, we show that quark confinement ascribes to the inevitable fractionality caused by coprimeness between half-integer (1/2) of isospin and number of composite particles (e.g. three).Comment: 14 pages, 4 figures, 2 table