Oxygen adsorption effect on magnetic properties of graphite

Both experimental and theoretical studies of the magnetic properties of micrographite and nanographite indicate a crucial role of the partial oxidation of graphitic zigzag edges in ferromagnetism. In contrast to total and partial hydrogenation, the oxidation of half of the carbon atoms on the graphite edges transforms the antiferromagnetic exchange interaction between graphite planes and over graphite ribbons to the ferromagnetic interaction. The stability of the ferromagnetism is discussed.Comment: 14 pages, 6 figure

Black string corrections in variable tension braneworld scenarios

Braneworld models with variable tension are investigated, and the corrections on the black string horizon along the extra dimension are provided. Such corrections are encrypted in additional terms involving the covariant derivatives of the variable tension on the brane, providing profound consequences concerning the black string horizon variation along the extra dimension, near the brane. The black string horizon behavior is shown to be drastically modified by the terms corrected by the brane variable tension. In particular, a model motivated by the phenomenological interesting case regarding Eotvos branes is investigated. It forthwith provides further physical features regarding variable tension braneworld scenarios, heretofore concealed in all previous analysis in the literature. All precedent analysis considered uniquely the expansion of the metric up to the second order along the extra dimension, what is able to evince solely the brane variable tension absolute value. Notwithstanding, the expansion terms aftermath, further accomplished in this paper from the third order on, elicits the successive covariant derivatives of the brane variable tension, and their respective coupling with the extrinsic curvature, the Weyl tensor, and the Riemann and Ricci tensors, as well as the scalar curvature. Such additional terms are shown to provide sudden modifications in the black string horizon in a variable tension braneworld scenarioComment: 12 pages, 5 figures, accepted in PR

Notes on the Two-brane Model with Variable Tension

Motivated by possible extensions of the braneworld models with two branes, we investigate some consequences of a variable brane tension using the well established results on consistency conditions. By a slight modification of the usual stress-tensor used in order to derive the braneworld sum rules, we find out some important constraints obeyed by time dependent brane tensions. In particular it is shown that the tensions of two Randall-Sundrum like branes obeying, at the same time, an Eotvos law, aggravate the fine tuning problem. Also, it is shown that if the hidden brane tension obeys an Eotvos law, then the visible brane has a mixed behavior allowing a bouncing-like period at early times while it is dominated by an Eotvos law nowadays. To finalize, we discuss some qualitative characteristics which may arise in the scope of dynamical brane tensions, as anisotropic background and branons production.Comment: 7 pages, 1 figure, accepted for publication in Physical Review

Stretching the peace: The role of Kundalini yoga in the lives of young people in Alexandra, South Africa

The purpose of this exploratory study is to underline the importance of a humanistic approach to peace studies against a scenario characterized by the failings and weaknesses of the liberal peacebuilding agenda. To do so, we employ a transrational peace research framework to investigate whether Kundalini yoga can be used as a peacebuilding tool by analyzing its role in the lives of young people living in an Alexandra township, in South Africa. We conducted semistructured interviews with yoga instructors, surveyed yogis online, and analyzed three annual reports of Yoga4Alex, an organization that provides young people in Alexandra with tools for a better life through Kundalini yoga (and other programs). The main findings of this study demonstrate that practicing Kundalini yoga plays a vital role in the yogis’ lives in Alexandra, creating a space where peace can grow. Many respondents consider that yoga creates a community that offers them support and mental well-being. Moreover, yoga practice helps to develop tools they can use for personal transformation, contributing to the creation of a new identity and offering a nonviolent alternative for everyday life. This study provides reflections for both research and practice.info:eu-repo/semantics/publishedVersio