Reproductive factors and risk of melanoma : a population-based cohort study

Background The association between reproductive factors and risk of cutaneous melanoma (CM) is unclear. We investigated this issue in the Norwegian Women and Cancer cohort study. Objectives To examine the association between the reproductive factors age at menarche, menstrual cycle length, parity, age at first and last birth, menopausal status, breastfeeding duration and length of ovulatory life, and CM risk, overall and by histological subtypes and anatomical site. Methods We followed 165 712 women aged 30-75 years at inclusion from 1991-2007 to the end of 2015. Multivariable Cox regression was used to estimate hazard ratios (HRs) with 95% confidence intervals (CIs). Results The mean age at cohort enrolment was 49 years. During a median follow-up of 18 years, 1347 cases of CM were identified. No reproductive factors were clearly associated with CM risk. When stratifying by histological subtype we observed significant heterogeneity (P = 0 center dot 01) in the effect of length of ovulatory life on the risk of superficial spreading melanoma (HR 1 center dot 02, 95% CI 1 center dot 01-1 center dot 04 per year increase) and nodular melanoma (HR 0 center dot 97, 95% CI 0 center dot 94-1 center dot 01 per year increase). When stratifying by anatomical site, menopausal status (HR 0 center dot 54, 95% CI 0 center dot 31-0 center dot 92, postmenopausal vs. premenopausal) and menstrual cycle length (HR 1 center dot 07, 95% CI 1 center dot 01-1 center dot 13, per day increase) were associated with CM of the trunk, and significant heterogeneity between anatomical sites was observed for menopausal status (P = 0 center dot 04). Conclusions In this large population-based Norwegian cohort study, we did not find convincing evidence of an association between reproductive factors and risk of CM.Peer reviewe

A Finite Element Computation of the Gravitational Radiation emitted by a Point-like object orbiting a Non-rotating Black Hole

The description of extreme-mass-ratio binary systems in the inspiral phase is a challenging problem in gravitational wave physics with significant relevance for the space interferometer LISA. The main difficulty lies in the evaluation of the effects of the small body's gravitational field on itself. To that end, an accurate computation of the perturbations produced by the small body with respect the background geometry of the large object, a massive black hole, is required. In this paper we present a new computational approach based on Finite Element Methods to solve the master equations describing perturbations of non-rotating black holes due to an orbiting point-like object. The numerical computations are carried out in the time domain by using evolution algorithms for wave-type equations. We show the accuracy of the method by comparing our calculations with previous results in the literature. Finally, we discuss the relevance of this method for achieving accurate descriptions of extreme-mass-ratio binaries.Comment: RevTeX 4. 18 pages, 8 figure

Antisymmetrization of a Mean Field Calculation of the T-Matrix

The usual definition of the prior(post) interaction $V(V^\prime )$ between projectile and target (resp. ejectile and residual target) being contradictory with full antisymmetrization between nucleons, an explicit antisymmetrization projector ${\cal A}$ must be included in the definition of the transition operator, $T\equiv V^\prime{\cal A}+V^\prime{\cal A}GV.$ We derive the suitably antisymmetrized mean field equations leading to a non perturbative estimate of $T$. The theory is illustrated by a calculation of forward $\alpha$-$\alpha$ scattering, making use of self consistent symmetries.Comment: 30 pages, no figures, plain TeX, SPHT/93/14

(I)Migrantes, diversidades e desigualdades no sistema educativo português : balanço e perspectivas

O objectivo do presente artigo consiste em procurar transmitir um olhar sociologicamente informado no que concerne à situação portuguesa no domínio das políticas educativas públicas e investigações produzidas relacionadas com o sistema educativo e a (i)migração, ou seja, com a tentativa de construção de uma educação intercultural. Neste sentido, será realizada uma análise descritiva e compreensivo-interpretativa da evolução desta problemática em Portugal desde que a mesma se tornou objecto de reflexão por parte de investigadores/as e políticos nos finais da década de oitenta, início da década de noventa do século XX. Nesta análise, será dada ênfase às investigações e quadros teóricos produzidos e às medidas legislativas e políticas educativas no domínio do tratamento da diferença cultural dentro do sistema educativo português.The aim of this article consists in attempting to transmit a sociologically informed view in what the Portuguese situation in the field of public policies and research related to the educational system and (im)migration are concerned, that is, in attempting to construct an intercultural education. In this way, a descriptive and comprehensiveinterpretative analysis of the evolution of this problem in Portugal will be realized, since the latter became an object of reflection on the part of researchers and politicians towards the end of the 80s, the beginning of the 90s of the XXth century. In this analysis, emphasis will be given on the research and theoretical frameworks produced and on the legislative measures and educational policies in the field of treating cultural difference in the Portuguese educational system

Stability of vortices in rotating taps: a 3d analysis

We study the stability of vortex-lines in trapped dilute gases subject to rotation. We solve numerically both the Gross-Pitaevskii and the Bogoliubov equations for a 3d condensate in spherically and cilyndrically symmetric stationary traps, from small to very large nonlinearities. In the stationary case it is found that the vortex states with unit and $m=2$ charge are energetically unstable. In the rotating trap it is found that this energetic instability may only be suppressed for the $m=1$ vortex-line, and that the multicharged vortices are never a local minimum of the energy functional, which implies that the absolute minimum of the energy is not an eigenstate of the $L_z$ operator, when the angular speed is above a certain value, $\Omega > \Omega_2$.Comment: 10 pages, 7 figures in EPS forma

Can a student learn optimally from two different teachers?

We explore the effects of over-specificity in learning algorithms by investigating the behavior of a student, suited to learn optimally from a teacher $\mathbf{B}$, learning from a teacher $\mathbf{B}'\neq\mathbf{B}$. We only considered the supervised, on-line learning scenario with teachers selected from a particular family. We found that, in the general case, the application of the optimal algorithm to the wrong teacher produces a residual generalization error, even if the right teacher is harder. By imposing mild conditions to the learning algorithm form we obtained an approximation for the residual generalization error. Simulations carried in finite networks validate the estimate found.Comment: 20 pages, 4 figure

Localizing gravity on Maxwell gauged CP1 model in six dimensions

We shall consider about a 3-brane embedded in six-dimensional space-time with a negative bulk cosmological constant. The 3-brane is constructed by a topological soliton solution living in two-dimensional axially symmetric transverse subspace. Similar to most previous works of six-dimensional soliton models, our Maxwell gauged CP1 brane model can also achieve to localize gravity around the 3-brane. The CP1 field is described by a scalar doublet and derived from O(3) sigma model by projecting it onto two-dimensional complex space. In that sense, our framework is more effective than other solitonic brane models concerning with gauge theory. We shall also discuss about linear stability analysis for our new model by fluctuating all fields.Comment: 23 pages, 7 figures; references adde

Fermi surface topology and low-lying quasiparticle structure of magnetically ordered Fe1+xTe

We report the first photoemission study of Fe1+xTe - the host compound of the newly discovered iron-chalcogenide superconductors. Our results reveal a pair of nearly electron- hole compensated Fermi pockets, strong Fermi velocity renormalization and an absence of a spin-density-wave gap. A shadow hole pocket is observed at the "X"-point of the Brillouin zone which is consistent with a long-range ordered magneto-structural groundstate. No signature of Fermi surface nesting instability associated with Q= pi(1/2, 1/2) is observed. Our results collectively reveal that the Fe1+xTe series is dramatically different from the undoped phases of the high Tc pnictides and likely harbor unusual mechanism for superconductivity and quantum magnetic order.Comment: 5 pages, 4 Figures; Submitted to Phys. Rev. Lett. (2009

La gestion démocratique des écoles: de l´autogouvernement à l’émergence d’une post-démocratie gestionnaire?

O autor assinala três elementos básicos que têm sido historicamente associados à gestão democrática das escolas: eleição, colegialidade, participação na decisão. A combinação ou rejeição de algumas dessas diferentes dimensões, em contextos sociais específicos, pode resultar em várias concepções de gestão democrática das escolas, desde o autogoverno até à possível ascensão de uma pós-democracia gestionária.The author points out three basic elements that have been historically associated with the democratic management of schools: election, collegiality, participation in decision-making. The combination or the rejection of some of those different dimensions in specific social contexts may result in various conceptions of democratic management of schools, from selfgovernment to the possible rise of a managerial post-democracyL’auteur souligne trois éléments de base qui ont été historiquement associés à la gestion démocratique des écoles: l’élection, la collégialité, la participation à la décision. La combinaison ou le rejet de certaines de ces différentes dimensions, dans des contextes sociaux spécifiques, peuvent entraîner des diverses conceptions de la gestion démocratique des écoles, de l’autogouvernement à l’émergence d’une post-démocratie gestionnaire(undefined