The paradox of parallel lives: immigration policy and transnational polygyny between Senegal and France

In Dakar, everyday conversations are filled with entertaining stories about the adventures of returning migrants. One common theme involves the visit of a Senegalese man who has returned from Europe with a foreign spouse. The most entertaining part of the story comes when the man’s family and friends go to great pains to conceal the existence of another wife and children in Senegal. In one version, the Senegalese wife is introduced to the European one as the husband’s “sister” or “cousin,” thereby deceiving the European wife into believing that the children in the household are her husband’s nieces and nephews whereas in fact they are his own children (see also Salomon 2009). The most appreciated elements of the story are usually the tricks deployed by various family members to maintain the illusion of a biological relationship between the husband and his “sister.” The truth is finally revealed when, for example, a child, a family member, or a jealous rival reveals who really is who

Introduction: dance in Africa and beyond: creativity and identity in a globalized world

In this introduction to the special issue on dance in Africa and beyond, we review the anthropological study of dance in Africa since the 1920s and introduce the seven contributions, organized around the key themes of transformed identities (both contemporary and historical), decoloniality, new media, morality, and the problematic representations of African diasporic identities in contemporary Europe. With this special issue, we argue that the study of dance and music provides an important window into the myriad creative ways in which people in Africa and in the African diaspora deal with problematic situations, generate new artistic forms, engage with questions of ethics, and carve out spaces in which they experiment with novelty and reinvigorate their lives

Weeklong improved colour contrasts sensitivity after single 670 nm exposures associated with enhanced mitochondrial function

Mitochondrial decline in ageing robs cells of ATP. However, animal studies show that long wavelength exposure (650-900 nm) over weeks partially restores ATP and improves function. The likely mechanism is via long wavelengths reducing nanoscopic interfacial water viscosity around ATP rota pumps, improving their efficiency. Recently, repeated 670 nm exposures have been used on the aged human retina, which has high-energy demands and significant mitochondrial and functional decline, to improve vision. We show here that single 3 min 670 nm exposures, at much lower energies than previously used, are sufficient to significantly improve for 1 week cone mediated colour contrast thresholds (detection) in ageing populations (37-70 years) to levels associated with younger subjects. But light needs to be delivered at specific times. In environments with artificial lighting humans are rarely dark-adapted, hence cone function becomes critical. This intervention, demonstrated to improve aged mitochondrial function can be applied to enhance colour vision in old age

S'aimer sous les yeux de l’État : les couples binationaux et le vécu du contrôle de la migration de mariage en France

En France, les femmes étrangères victimes de violences conjugales, en rompant la vie commune avec leur époux, risquent de perdre leur droit au séjour. Si elles sont en capacité de prouver les violences dont elles ont été victimes par des plaintes, des certificats médicaux, elles peuvent espérer obtenir un titre de séjour. Malheureusement, souvent ces preuves sont absentes, car ces femmes sont dans des situations qui ne leur permettent pas de rassembler les éléments nécessaires. Quand les preuves font défaut, les avocats et les associations qui les accompagnent mettent en place des stratégies spécifiques pour obtenir une régularisation en s’appuyant sur d’autres critères qu’elles peuvent remplir. Ce faisant, ils passent sous silence les violences conjugales, ces femmes ne sont jamais reconnues comme victimes et leurs conjoints violents jamais sanctionnés. / In France, foreign women victims of domestic violence, breaking the common life with their spouse, may lose their right to stay. If they are able to prove the violence they have suffered from by complaints, medical certificates, they can expect to obtain a residence permit. Unfortunately, often the evidence is lacking because these women are in situations that do not allow them to collect the necessary items. When the evidences are lacking, lawyers and associations accompanying the women implement specific strategies for regularize their administrative situation on the basis of other criteria that they can fulfil. In doing so, domestic violence disappeared and these women are never recognized as victims and the authors of the violence never punished

Exact 1/N and Optimized Perturbative Evaluation of mu_c for Homogeneous Interacting Bose Gases

In the framework of the O(N) three-dimensional effective scalar field model for homogeneous dilute weakly interacting Bose gases we use the 1/N expansion to evaluate, within the large N limit, the parameter r_c which is directly related to the critical chemical potential mu_c. This quantity enters the order-a^2 n^{2/3} coefficient contributing to the critical temperature shift Delta T_c where a represents the s-wave scattering length and n represents the density. Compared to the recent precise numerical lattice simulation results, our calculation suggests that the large N approximation performs rather well even for the physical case N=2. We then calculate the same quantity but using different forms of the optimized perturbative (variational) method, showing that these produce excellent results both for the finite N and large-N cases.Comment: 12 pages, 2 figures. We have performed a refined and extended numerical analysis to take into account the very recent results of Ref. [15

Survival of near-critical branching Brownian motion

Consider a system of particles performing branching Brownian motion with negative drift $\mu = \sqrt{2 - \epsilon}$ and killed upon hitting zero. Initially there is one particle at $x>0$. Kesten showed that the process survives with positive probability if and only if $\epsilon>0$. Here we are interested in the asymptotics as \eps\to 0 of the survival probability $Q_\mu(x)$. It is proved that if $L= \pi/\sqrt{\epsilon}$ then for all $x \in \R$, $\lim_{\epsilon \to 0} Q_\mu(L+x) = \theta(x) \in (0,1)$ exists and is a travelling wave solution of the Fisher-KPP equation. Furthermore, we obtain sharp asymptotics of the survival probability when $x<L$ and $L-x \to \infty$. The proofs rely on probabilistic methods developed by the authors in a previous work. This completes earlier work by Harris, Harris and Kyprianou and confirms predictions made by Derrida and Simon, which were obtained using nonrigorous PDE methods

A new improved optimization of perturbation theory: applications to the oscillator energy levels and Bose-Einstein critical temperature

Improving perturbation theory via a variational optimization has generally produced in higher orders an embarrassingly large set of solutions, most of them unphysical (complex). We introduce an extension of the optimized perturbation method which leads to a drastic reduction of the number of acceptable solutions. The properties of this new method are studied and it is then applied to the calculation of relevant quantities in different $\phi^4$ models, such as the anharmonic oscillator energy levels and the critical Bose-Einstein Condensation temperature shift $\Delta T_c$ recently investigated by various authors. Our present estimates of $\Delta T_c$, incorporating the most recently available six and seven loop perturbative information, are in excellent agreement with all the available lattice numerical simulations. This represents a very substantial improvement over previous treatments.Comment: 9 pages, no figures. v2: minor wording changes in title/abstract, to appear in Phys.Rev.

The eyes of the deep diving hooded seal (Cystophora cristata) enhance sensitivity to ultraviolet light

The mammalian visual range is approximately 400-700nm, although recent evidence suggests varying ultraviolet (UV) extensions in diverse terrestrial species. UV sensitivity may have advantages in the dim, blue light shifted environment experienced by submerged marine mammals. It may also be advantageous when seals are hauled out as UV is reflected by snow and ice but absorbed by fur, enhancing visual contrast. Here we show that the pelagic hooded seal (Cystophora cristata) has a highly UV permissive cornea and lens. Seals like other carnivores have a tapetum lucidum (TL) reflecting light back through the retina increasing sensitivity. The TL in this seal is unusual being white and covering almost the entire retina unlike that in other carnivores. Spectral reflectance from its surface selectively increases the relative UV/blue components >10 times than other wavelengths. Retinal architecture is consistent with a high degree of convergence. Enhanced UV from a large TL surface with a high degree of retinal convergence will increase sensitivity at a cost to acuity. UV electrophysiological retina responses were only obtained to dim, rod mediated stimuli, with no evidence of cone input. As physiological measurements of threshold sensitivity are log units higher than those for psychophysical detection, these seals are likely to be more UV sensitive than our results imply. Hence, UV reflections from the TL will afford increased sensitivity in dim oceanic environments