Gauss-Bonnet black holes with non-constant curvature horizons

We investigate static and dynamical n(\ge 6)-dimensional black holes in Einstein-Gauss-Bonnet gravity of which horizons have the isometries of an (n-2)-dimensional Einstein space with a condition on its Weyl tensor originally given by Dotti and Gleiser. Defining a generalized Misner-Sharp quasi-local mass that satisfies the unified first law, we show that most of the properties of the quasi-local mass and the trapping horizon are shared with the case with horizons of constant curvature. It is shown that the Dotti-Gleiser solution is the unique vacuum solution if the warp factor on the (n-2)-dimensional Einstein space is non-constant. The quasi-local mass becomes constant for the Dotti-Gleiser black hole and satisfies the first law of the black-hole thermodynamics with its Wald entropy. In the non-negative curvature case with positive Gauss-Bonnet constant and zero cosmological constant, it is shown that the Dotti-Gleiser black hole is thermodynamically unstable. Even if it becomes locally stable for the non-zero cosmological constant, it cannot be globally stable for the positive cosmological constant.Comment: 15 pages, 1 figure; v2, discussion clarified and references added; v3, published version; v4, Eqs.(4.22)-(4.24) corrected, which do not change Eqs.(4.25)-(4.27

Evaluation of Antenatal Screening for Neural Tube Defects in Glasgow 1976-1986: An Epidemiological Study

Glasgow suffers one of the highest prevalence rates of congenital neural tube defects in the world. There have been reports of a long-term decline in the prevalence of neural tube defects although the reasons for it are unclear. Anencephaly is always fatal while, even with active treatment, spina bifida is associated with high rates of early infant mortality and a high degree of physical and mental impairment in the survivors. Antenatal screening followed by induced abortion is the only available means of avoiding such births

Exact dynamical AdS black holes and wormholes with a Klein-Gordon field

We present several classes of exact solutions in the Einstein-Klein-Gordon system with a cosmological constant. The spacetime has spherical, plane, or hyperbolic symmetry and the higher-dimensional solutions are obtained in a closed form only in the plane symmetric case. Among them, the class-I solution represents an asymptotically locally anti-de Sitter (AdS) dynamical black hole or wormhole. In four and higher dimensions, the generalized Misner-Sharp quasi-local mass blows up at AdS infinity, inferring that the spacetime is only locally AdS. In three dimensions, the scalar field becomes trivial and the solution reduces to the BTZ black hole.Comment: 11 pages, 2 figures, 2 tables; v2, results strengthened, argument on trapping horizon corrected; v3, argument on locally AdS property added, accepted for publication in Physical Review

Direct Separation of Short Range Order in Intermixed Nanocrystalline and Amorphous Phases

Diffraction anomalous fine-structure (DAFS) and extended x-ray absorption fine-structure (EXAFS) measurements were combined to determine short range order (SRO) about a single atomic type in a sample of mixed amorphous and nanocrystalline phases of germanium. EXAFS yields information about the SRO of all Ge atoms in the sample, while DAFS determines the SRO of only the ordered fraction. We determine that the first-shell distance distribution is bimodal; the nanocrystalline distance is the same as the bulk crystal, to within 0.01(2)   Å, but the mean amorphous Ge-Ge bond length is expanded by 0.076(19)   Å. This approach can be applied to many systems of mixed amorphous and nanocrystalline phases

Hall effect in superconducting Fe(Se0.5Te0.5) thin films

The Hall effect is investigated for eight superconducting Fe(Se_0.5_Te_0.5_) thin films grown on MgO and LaSrAlO_4_ substrates with different transition temperatures (T_c_). The normal Hall coefficients (R_H_) have positive values with magnitude of 1 - 1.5 x 10^-3^ cm^3^/C at room temperature for the all samples. With decreasing temperature, we find two characteristic types of behavior in R_H_(T) depending on T_c_. For thin films with lower T_c_ (typically T_c_ < 5 K), R_H_ start decreasing approximately below T = 250 K toward a negative side, some of which shows sign reversal at T = 50 - 60 K, but turns positive toward T = 0 K. On the other hand for the films with higher T_c_ (typically T_c_ > 9 K), R_ H_ leaves almost unchanged down to T = 100 K, and then starts decreasing toward a negative side. Around the temperatures when R_H_ changes its sign from positive to negative, obvious nonlinearity is observed in the field-dependence of Hall resistance as to keep the low-field R_H_ positive while the high-field R_H_ negative. Thus the electronic state just above T_c_ is characterized by n_e_ (electron density) > n_h_ (hole density) with keeping \mu_e_ < \mu_h_. These results suggest the dominance of electron density to the hole density is an essential factor for the occurence of superconductivity in Fe-chalcogenide superconductors.Comment: 11 pages, 4 figures, revised version for Physical Review B. accepted for publication in Physical Review

Propriedades químicas de solo tratado com resíduos da indústria de celulose e papel.

A utilização de resíduos gerados nas indústrias de celulose e papel como insumo agrícola e florestal é uma alternativa para o problema de descarte, além de contribuir para a redução do custo da produção agrícola e florestal. No entanto, para o uso adequado e seguro desses resíduos, torna-se necessário conhecer seus efeitos em atributos químicos do solo. Foi avaliado o efeito de doses de carbonato de cálcio, cinza de biomassa florestal, lama de cal e lodos celulósicos em atributos químicos de um Neossolo Regolítico Distrófico húmico. O pH e os teores de Ca, Mg e P aumentaram com o aumento das doses testadas, enquanto o teor de Al e sua saturação reduziram com a aplicação de todos os materiais avaliados. Os teores de K aumentaram principalmente pela aplicação de cinzas de madeira. A relação Ca/Mg foi elevada pela aplicação de carbonato de cálcio, lama de cal e lodo celulósico a valores que podem ser prejudiciais. As cinzas foram importantes fontes de K, Ca, Mg e P