Gibbs sampling methods for Pitman-Yor mixture models

We introduce a new sampling strategy for the two-parameter Poisson-Dirichlet process mixture model, also known as Pitman-Yor process mixture model (PYM). Our sampler is therefore applicable to the well-known Dirichlet process mixture model (DPM). Inference in DPM and PYM is usually performed via Markov Chain Monte Carlo (MCMC) methods, specifi cally the Gibbs sampler. These sampling methods are usually divided in two classes: marginal and conditional algorithms. Each method has its merits and limitations. The aim of this paper is to propose a new sampler that combines the main advantages of each class. The key idea of the proposed sampler consists in replacing the standard posterior updating of the mixing measure based on the stick-breaking representation, with a posterior updating of Pitman(1996) which represents the posterior law under a Pitman-Yor process as the sum of a jump part and a continuous one. We sample the continuous part in two ways, leading to two variants of the proposed sampler. We also propose a threshold to improve mixing in the first variant of our algorithm. The two variants of our sampler are compared with a marginal method, that is the celebrated Algorithm 8 of Neal(2000), and two conditional algorithms based on the stick-breaking representation, namely the efficient slice sampler of Kalli et al. (2011) and the truncated blocked Gibbs sampler of Ishwaran and James (2001). We also investigate e ffects of removing the proposed threshold in the first variant of our algorithm and introducing the threshold in the efficient slice sampler of Kalli et al. (2011). Results on real and simulated data sets illustrate that our algorithms outperform the other conditionals in terms of mixing properties

La finance islamique et les marchés boursiers

Notre étude a pour objet l'analyse des marchés boursiers en présence de finance islamique. Nous faisons ici l'hypothèse que finance islamique et finance conventionnelle ne sont pas entièrement indépendantes et prenons en compte l'interaction pouvant exister entre les deux. D'une manière générale, nous étudions l'impact de la finance islamique sur la structure des rendements boursiers de 7 pays d'Asie-Pacifique. Les données ont été recueillies sur une période de 11 ans (janvier 2001 à décembre 2011) et, par égard à la crise financière de 2008, deux sous périodes ont été définies : la première allant de janvier 2001 à décembre 2007 (pré-crise), et la seconde, de janvier 2008 à décembre 2011 (post-crise). Globalement, la finance islamique semble avoir une influence positive sur les rendements de pays ayant une population à prédominance musulmane. Nous constatons également que les variables islamiques tendent à être plus significatives en période de crise et parvenons à déceler un effet positif des jours de Ramadan sur les rendements des indices considérés

Plantes médicinales utilisées dans le traitement traditionnel du paludisme à Bamako (Mali)

Le paludisme constitue un problème de santé publique à Bamako et l’utilisation des plantes dans sa prise en charge est fréquente. Cependant beaucoup de menaces pèsent sur ces plantes à cause de plusieurs facteurs dont leur méconnaissance d’où la nécessité de les connaitre pour améliorer leur gestion et leur conservation. Une enquête ethnobotanique a été conduite à Bamako d’Août 2012 à Novembre 2012. Les résultats ont montré que 52 espèces reparties dans 48 genres, 24 familles sont utilisées. Les familles les plus représentées étaient les Caesalpiniaceae, les Rubiaceae, les Combretaceae, les Euphorbiaceae et les Fabaceae. Cette flore était dominée surtout par les espèces africaines et pantropicales. Le type biologique le plus nombreux était constitué par les phanérophytes. Les feuilles constituaient la partie la plus utilisée, la préparation la plus utilisée était la décoction. Les résultats de cette étude pourront ainsi contribuer à la connaissance exhaustive des plantes à visée antipaludique et à une valorisation de la médecine traditionnelle Malienne.© 2016 International Formulae Group. All rights reserved.Mots clés: Paludisme, plantes médicinales, ethnobotanique, BamakoEnglish Title: Medicinal plants used in traditional treatment of malaria in Bamako (Mali)English AbstractMalaria is a public health problem in Bamako and the use of plants in its management is common. However many threats to these plants were observed because of several factors including their lack of the need to know them to improve their management and conservation. An ethnobotanical survey was conducted in Bamako from August 2012 to November 2012. The results showed that 52 species distributed in 48 genera, 24 families are used. The most represented families were Caesalpiniaceae, Rubiaceae, the Combretaceae,  Euphorbiaceae and Fabaceae. This flora was dominated mostly by African and pan-tropical species. The largest biological type was made by phanerophytes. The leaves are the most used part of the most common preparation was the decoction. The results of this study could contribute to the comprehensive knowledge of plants with antimalarial properties and valorization of traditional Malian medicine.© 2016 International Formulae Group. All rights reserved.Keywords: Malaria, medicinal plants, ethnobotany, Bamak

Knowledge and attitudes of Senegalese sailors about HIV/AIDS

Background: In West Africa there is little information on the behavior of sailors with respect to HIV/AIDS.Aim: The objective of this study was to assess the knowledge and attitudes on HIV/AIDS and their risk factors.Materials and methods: This was a cross-sectional study on a sample of 400 sailors. Information was collected on knowledge and attitudes. Multiple logistic regression was performed to analyse the factors related to knowledge and attitudes.Results: The mean age was 38.1 ± 9.8 years. Among sailors, 7.5% knew the 3 main modes of HIV transmissionand 48.3% did not sail with a crew member infected with HIV. Knowledge was related to occupationalcategory (OR = 14.07 [5.40–36.65]). Stigmatisation was related to education (OR = 0.45 [0.27–0.74]) and fear (0.19 [0.09–0.41]).Conclusions: Sailors have a low level of knowledge and negative attitudes towards people living with HIV. Intervention simplemented must take into account the low level of knowledge and the mobility of the target population

Analysis of cesarean section rate according to Robson’s classification in an urban health centre in Senegal

Background: Robson, proposed a new classification system, the Robson’s Ten-Group Classification System to allow critical analysis according to characteristics of pregnancy. The objective was to describe caesarean rates in an urban health centre in Dakar using Robson’s Ten groups classificationMethods: This study was performed in Philippe Senghor health centre in Dakar (Senegal), a secondary health centre that performs CS since 2011. Before this date, only midwifes performed deliveries in this centre. The study took place between 1 January and 31 December 2013. All patients who delivered during this period by CS were included.Women were classified in 10 groups according to Robson’s classification, using maternal characteristics and obstetrical history. For each group, we calculated its relative size and its contribution to the overall caesarean rate.Results: The overall rate of caesarean was 18.2%. The main contributors to the overall caesarean rate were primiparous women in spontaneous labour (group 1) and women with previous caesarean section (group 5). Further analysis of group 1 showed that more than half of CS indications in this group were fetal-pelvic disproportion in 55.2% and fetal hypoxia in 27%.Conclusion: The Robson’s classification is easy to use. Each maternity unit can compare its rates with those of units with similar level, to find whether some groups of women have very high rates of caesarean sections. Attention should be made because CS rates is rising up and will be problematic in our low resource countries. It is time to implement obstetric audits to lower the CS rates

Inflammatory breast cancer: features and outcomes in a breast unit in Dakar, Senegal

Background: The aim of this study was to determine clinical features and outcomes of patients with inflammatory breast cancer (IBC) treated in our breast unit.Methods: This study was performed at Gynaecologic and Obstetric Clinic of Dakar Teaching Hospital, in which a breast unit was created since 2007. All women with diagnosis of inflammatory breast cancer in our Breast Unit between January 2010 and December 2013 were included in this study. The diagnosis of IBC was made clinically using the American Joint Committee on Cancer (AJCC) and confirmed histologically. The follow-up cut-off for this data set was December 31st, 2014. All analyses for this study were performed using SPSS software (version 20.0).Results: Between 2010 and 2013, 22 women with breast cancer who met eligibility criteria were included out of 161 patients followed for breast cancer leading to a frequency of 13.6%. The median age at diagnosis was 43.4 years (26-79 years). Mean time to diagnosis was 4 months. The mean time to recurrence was 11.2 months. This recurrence was observed in 45.5% of cases. The median overall survival was 13.3 months (CI 95% 8.576-18.526), the survival rate was 31.8%.Conclusions: This series shows a high frequency of inflammatory breast cancer. These tumours are very aggressive with a very poor prognosis

Invasive mole: a rare cause of postmenopausal bleeding

Gestational trophoblastic disease (GTD) describes a number of gynaecological tumours that originate in the trophoblast layer, including hydatidiform mole (complete or partial), placental site trophoblastic tumour, choriocarcinoma and invasive mole. Invasive moles are responsible of most cases of localized gestational trophoblastic neoplasia (GTN). Invasive mole is a condition where a molar pregnancy, such as a partial hydatidiform mole or complete hydatidiform mole, invades the wall of the uterus. It is an extremely rare condition. As GTN is not considered in the differential diagnosis of postmenopausal uterine malignancies, its preoperative diagnosis is challenging. We report a case of invasive hydatidiform mole in a postmenopausal woman discovered in a context of postmenopausal bleeding. She underwent hysterectomy and followed up till her beta hCG levels were within normal limits. The patient is in complete remission in the first postoperative year.

Puerperal uterine inversion: a new case report

Puerperal uterine inversion is a rare and severe affection which the uterine fundus collapses into the endometrial cavity. The diagnosis is essentially made on clinical examination, which also allows to determinate the gravity. The management must be done early, which can be surgical or non-surgical. Through a case study we will review the literature

About a case of a specific complication of monoamniotic twin pregnancy: umbilical cord entanglement

Monoamniotic twin pregnancies are uncommon and often complicated by umbilical cord entanglement. It is important to investigate a umbilical cord entanglement during antenatal ultrasound examinations. The diagnosis is based on ultrasound with color and pulsed Doppler. Despite the high percentage of cord entanglement, the perinatal mortality rate remains very low. Rigorous ultrasound monitoring and recording of fetal heart rhythms can improve the prognosis. We report a case of umbilical cord entanglement in a monoamniotic twin pregnancy discovered during a caesarean section with a favorable outcome

Choriocarcinoma with uterine rupture presenting as acute haemoperitoneum and shock

Choriocarcinoma is a rare neoplasm and a malignant form of gestational trophoblastic disease. Invasive mole may perforate uterus through the myometrium resulting in uterine perforation and intraperitoneal bleeding. But uterine perforation due to choriocarcinoma is rare. We present a case of a young woman who presented 1 year after uterine evacuation of a molar pregnancy with invasive choriocarcinoma complicated by a uterine rupture and haemoperitoneum