A characterization of quadric constant mean curvature hypersurfaces of spheres

Let $\phi:M\to\mathbb{S}^{n+1}\subset\mathbb{R}^{n+2}$ be an immersion of a complete $n$-dimensional oriented manifold. For any $v\in\mathbb{R}^{n+2}$, let us denote by $\ell_v:M\to\mathbb{R}$ the function given by $\ell_v(x)=\phi(x),v$ and by $f_v:M\to\mathbb{R}$, the function given by $f_v(x)=\nu(x),v$, where $\nu:M\to\mathbb{S}^{n}$ is a Gauss map. We will prove that if $M$ has constant mean curvature, and, for some $v\ne{\bf 0}$ and some real number $\lambda$, we have that $\ell_v=\lambda f_v$, then, $\phi(M)$ is either a totally umbilical sphere or a Clifford hypersurface. As an application, we will use this result to prove that the weak stability index of any compact constant mean curvature hypersurface $M^n$ in $\mathbb{S}^{n+1}$ which is neither totally umbilical nor a Clifford hypersurface and has constant scalar curvature is greater than or equal to $2n+4$.Comment: Final version (February 2008). To appear in the Journal of Geometric Analysi

Bilateral and Unilateral Asymmetries of Strength and Flexibility in Young Elite Sailors: Windsurfing, Optimist and Laser Classes

In sport sailing, performance is related to the sailor’s ability to maintain the stability of the boat, and the boat class determines the variables involved in such ability. In monohull-type vessels, such as the Optimist and Laser classes, the flexibility of the hip joint is a key performance factor. In the Windsurfing class, performance is determined by the strength of the flexors of the fingers and elbows. The performance of the sailor may be a ected by asymmetries in the strength and flexibility of the muscles and joints involved in technical actions. The objective of this study was to evaluate asymmetries in strength and flexibility in young sailors. Thirty-three young sailors (ten girls) from the Windsurfing, Optimist and Laser classes were assessed for manual strength and flexibility, by dynamometry and straight leg lift tests, respectively. The symmetry index and the functional asymmetry of compression force were calculated. The results showed no di erences between sailors according to gender. The sailors of the Laser class obtained the highest levels of manual strength, whereas those of the Windsurfing class showed the highest flexibility levels. The girls’ group andWindsurfing class had the highest percentage of sailors with strength asymmetry, whereas, the sailors of the Optimist class presented a greater percentage of asymmetry in flexibility. There were no di erences in upper limb strength and lower limb flexibility between the dominant and non-dominant sides

Trauma, shame and performance: Towards a new topography of affects in black queer identities

Haitian American feminist and lesbian activist MilDred Gerestant has become one of the most acclaimed gender performers who best illustrates the malleability of gender, race and sexuality in the reconstruction of black queer identities. Drawing on interdisciplinary theoretical frameworks like trauma studies, queer theory and affect theory, my contribution analyses MilDred''s gender performances as creative attempts to surpass negative affects often attached to minority identities. By exploring the affect of shame as a productive enactment of transformation and hope, rather than as a source of numbness and suffering, this article aims to offer an alternative epistemological paradigm of feminist feeling and thinking, thus challenging mainstream discourses of identity and affective normalcy

Trauma, Shame and Performance: Towards a New Topography of Affects in Black Queer Identities

Haitian American feminist and lesbian activist MilDred Gerestant has become one of the most acclaimed gender performers who best illustrates the malleability of gender, race and sexuality in the reconstruction of black queer identities. Drawing on interdisciplinary theoretical frameworks like trauma studies, queer theory and affect theory, my contribution analyses MilDred’s gender performances as creative attempts to surpass negative affects often attached to minority identities. By exploring the affect of shame as a productive enactment of transformation and hope, rather than as a source of numbness and suffering, this article aims to offer an alternative epistemological paradigm of feminist feeling and thinking, thus challenging mainstream discourses of identity and affective normalcy

Optimización de la generación de un parque eólico considerando efectos de estela

El objetivo de este trabajo es verificar la hipótesis de que operar los diferentes aerogeneradores de un parque a velocidades específicas distintas de la óptima tiene como resultado un aumento en la velocidad del viento en las estelas y que éste comporta un aumento de la generación eléctrica total del parque. Para ello se hace un repaso de la teoría aerodinámica de aerogeneradores necesaria, se establece un caso de estudio y se simula. A partir de los resultados favorables se establece un sistema de operación que haga uso de este efecto para así mejorar la producción energética del parque en su conjunto

A reparative reading of feminism

The aim of this article is to offer a reparative framework for current feminist approaches, most of which seek to inhabit rather than assimilate previous forms of inclusivity or intersectionality, by vindicating the pioneering role of past feminisms. For this purpose, I will stick to a double-edged methodological tool that has been an object of dispute in feminist and literary studies for the last decades, namely, critique and postcritique, two concepts that could be said to bear witness to old and new ways of doing feminism. My aim is not to dismiss recent feminist work but to render visible forgotten critiques that have been an essential heritage of feminism. To acknowledge such debts is part of the reparative reading I present here, for I hold that the desire for deep knowledge is accretive and demands a closer and more respectful attention to past practices and theoretical positions

On the r−r-stability of spacelike hypersurfaces

In this paper we study the strong stability of spacelike hypersurfaces with constant $r$-th mean curvature in Generalized Robertson-Walker spacetimes of constant sectional curvature. In particular, we treat the case in which the ambient spacetime is the de Sitter space