Receiver Architectures for MIMO-OFDM Based on a Combined VMP-SP Algorithm

Iterative information processing, either based on heuristics or analytical frameworks, has been shown to be a very powerful tool for the design of efficient, yet feasible, wireless receiver architectures. Within this context, algorithms performing message-passing on a probabilistic graph, such as the sum-product (SP) and variational message passing (VMP) algorithms, have become increasingly popular. In this contribution, we apply a combined VMP-SP message-passing technique to the design of receivers for MIMO-ODFM systems. The message-passing equations of the combined scheme can be obtained from the equations of the stationary points of a constrained region-based free energy approximation. When applied to a MIMO-OFDM probabilistic model, we obtain a generic receiver architecture performing iterative channel weight and noise precision estimation, equalization and data decoding. We show that this generic scheme can be particularized to a variety of different receiver structures, ranging from high-performance iterative structures to low complexity receivers. This allows for a flexible design of the signal processing specially tailored for the requirements of each specific application. The numerical assessment of our solutions, based on Monte Carlo simulations, corroborates the high performance of the proposed algorithms and their superiority to heuristic approaches

Engagement de groupe, transformation des représentations sociales et modifications comportementales

Dans cette recherche, on s\u27intéresse à la modification d\u27une représentation sociale et à l\u27émission d\u27un comportement. Dans une première condition, les groupes sont composés de personnes « familières », dans la seconde condition, elles ne se connaissent pas. De plus, chaque groupe est divisé en deux sous-groupes, selon qu\u27il y a ou non signature d\u27un document. Il est, ensuite, demandé, aux étudiants, de participer à la mise en place d\u27une campagne de promotion et de valorisation des études. Les résultats montrent des modifications importantes, au niveau des éléments de la représentation sociale, ainsi qu\u27une acceptation plus importante du comportement demandé par l\u27expérimentateur, pour les sujets engagés et familiers. (French

Biharmonic pattern selection

A new model to describe fractal growth is discussed which includes effects due to long-range coupling between displacements $u$. The model is based on the biharmonic equation $\nabla^{4}u =0$ in two-dimensional isotropic defect-free media as follows from the Kuramoto-Sivashinsky equation for pattern formation -or, alternatively, from the theory of elasticity. As a difference with Laplacian and Poisson growth models, in the new model the Laplacian of $u$ is neither zero nor proportional to $u$. Its discretization allows to reproduce a transition from dense to multibranched growth at a point in which the growth velocity exhibits a minimum similarly to what occurs within Poisson growth in planar geometry. Furthermore, in circular geometry the transition point is estimated for the simplest case from the relation $r_{\ell}\approx L/e^{1/2}$ such that the trajectories become stable at the growing surfaces in a continuous limit. Hence, within the biharmonic growth model, this transition depends only on the system size $L$ and occurs approximately at a distance $60 \%$ far from a central seed particle. The influence of biharmonic patterns on the growth probability for each lattice site is also analysed.Comment: To appear in Phys. Rev. E. Copies upon request to [email protected]

Effects of oral contraceptives on spatial cognition depend on pharmacological properties and phase of the contraceptive cycle

The central nervous system effects of oral contraceptives (OCs) are not well-documented. In a set of 3 studies, we investigated a specific cognitive function, mental rotation, in healthy women currently using OCs for contraceptive purposes (n = 201) and in medication-free controls not using OCs (n = 44). Mental rotation was measured using a well-standardized and extensively validated psychometric test, the Vandenberg Mental Rotations Test (MRT). In an initial study (Study 1), current OC users (n = 63) were tested during the active or inactive phases of the contraceptive cycle in a parallel-groups design. Studies 2 and 3 were based on an archival dataset (n = 201 current OC users) that consisted of data on the MRT collected in real-time over a 30-year period and compiled for purposes of the present work. The OCs were combined formulations containing ethinyl estradiol (10-35 ug/day) plus a synthetic progestin. All 4 families of synthetic progestins historically used in OCs were represented in the dataset. Cognitive performance was evaluated during either active OC use (‘active phase’) or during the washout week of the contraceptive cycle (‘inactive phase’) when OC steroids are not used. The results showed a significant phase-of-cycle (POC) effect. Accuracy on the MRT was mildly diminished during the active phase of OC use, while scores on verbal fluency and speeded motor tasks were modestly improved. The POC effect was most evident in women using OCs that contained first- or second-generation progestins (the estrane family of progestins or OCs containing levonorgestrel), but not in women using OCs containing recently developed progestins and lower doses of ethinyl estradiol. Using independently established ratings of the estrogenic, androgenic, and progestogenic intensities of the different OC formulations, each brand of OC was classified according to its distinct endocrine profile. Multiple regression revealed that the effects of OC use on the MRT could be predicted based on the estrogenic strength of the contraceptives used. Estrogenic potency, not androgenic or anti-androgenic effects of the OC pill, may underlie the effects of OC usage on spatial cognition

The EU and US : friends or rivals

As boas relações entre a União Europeia e os EUA são essenciais para a estabilidade global. Mas as actuais relações transatlânticas permanecem constrangidas sobretudo como resultado da guerra no Iraque e da abordagem unilateral da primeira administração George W. Bush. As divergências entre UE-EUA têm aumentado nas áreas políticas e estratégicas bem como nas áreas económicas e sociais. Uma das maiores divergências incide sobre a governação global e sobre o papel atribuído à ONU e a outras instituições multilaterais. Também existe um elevado grau de anti-americanismo (ou de oposição às políticas da administração Bush) na Europa, e de ressentimento para com a Europa (ou melhor, para com a França e Alemanha) nos EUA. A UE não tem ideia de como lidar com a única superpotência mundial. Normalmente prefere- se o bilateral aos canais europeus. Mas as actuais estruturas UE-EUA não permitem uma discussão séria sobre muitas destas diferenças. Nem a OTAN é uma estrutura adequada para um diálogo estratégico transatlântico, como o chanceler Schroeder referiu na Conferencia Wehrkunde, em Munique, em Janeiro de 2005

Efficiency of the lausanne clinical pathway for proximal femoral fractures.

Purpose/Introduction: The number of hip fractures is rising, due to increases in life expectancy. In such cases, patients are at risk from post-operative complications and subsequently the average length of hospitalization may be extended. In 2011, we established a clinical pathway (CP), a specific model of care for patient-care management, to improve the clinical and economic outcomes of proximal femoral fracture management in elderly patients. The goal was to evaluate the CP using clinical, process, and financial indicators. METHODS: We included all surgical patients aged 65 and over, admitted to the emergency department with a fracture of the proximal femur following a fall. Assessment parameters included three performance indicators: clinical, process, and financial. The clinical indicators were the presence or absence of acute delirium on the third post-operative day, diagnosis of nosocomial pneumonia, and the number of patients fulfilling at least 75% of their nutritional requirements at the end of the hospitalization period. The process indicator was the time interval between arrival at the emergency department and surgery. The financial indicator was based on the number of days spent in hospital. RESULTS: From 2011 to 2013, 669 patients were included in the CP. We observed that the average length of stay in hospital decreased as soon as the CP was implemented and stabilized afterwards. The goal of 90% of patients undergoing surgery within 48 h of arrival in the emergency department was surpassed in 2013 (93.1%). Furthermore, we observed an improvement in the clinical indicators. CONCLUSION: The application of a CP allowed an improvement in the qualitative and quantitative efficiency of proximal femoral fracture management in elderly patients, in terms of clinical, process, and financial factors

Investigation of the prevalence of antibodies against neurotropic polyomaviruses BK, JC and SV40 in sera from patients affected by multiple sclerosis.

Viral agents seem to be linked to multiple sclerosis (MS). This association is based on evidence of (1) early exposure to viruses and MS onset; (2) increased prevalence of MS disease in specific geographic regions; (3) likelihood of developing MS being more prevalent in high-risk areas; (4) altered immune responses to different viruses. In this study, sera from patients affected by MS and controls, represented by sera from patients with other neurologic diseases, both inflammatory and non-inflammatory, and from healthy donors, were investigated for the presence of antibodies against neurotropic polyomaviruses BKV, JCV and SV40 in their sera. Our study has indicated that the prevalence of BKV antibodies in sera from MS patients is higher than that detected in normal individuals, while levels of antibodies against BKV and JCV are lower in MS patients compared to those of normal subjects