Sex determination in Bonellia viridis (Echiura : Bonelliidae) : population dynamics and evolution

In the echiuran worm Bonellia viridis Rolando, the vast majority of sexually undifferentiated larvae metamorphose into dwarf males that live inside the female when exposed to females, but differentiate into females when developing in the absence of females. By means of a spatially explicit, individual-based model the authors examine how this specific form of environmental sex determination (ESD) affects dynamics of Bonellia populations and investigate the selective advantage of ESD over the more widespread genotypic sex determination (GSD). Population dynamics of Bonellia appear rather simple and not too sensitive to parameter changes around their measured values, or to changes in distribution and sizes of inhabitable patches. Starting even from low sizes, populations soon attain equilibrium densities. Explored aspects of population dynamics indicate an advantage of ESD over GSD. Moreover, simulated invasibility experiments show that while the maternal inheritance scenario allows for fixation of GSD under some limited conditions, both the classical and proportional inheritance scenarios always lead to fixation of ESD in the population. This article also shows that only the ability of ESD larvae to adapt their ultimate sex both in competition for empty burrows and for mating within females gives them a competitive edge over nonadaptive response to feminising and/or masculinising signals and generally leads to fixation of ESD by small step evolution. The original hypothesis of Charnov and Bull thus needs to be refined in the sense that along with females forming an unpredictable resource for males, empty burrows are an unpredictable resource for femalespeer-reviewe

Management of the child with spina bifida

Meningomyelocele is one of the most important of the congenital anomalies of the spine, with an incidence of about 3 per 1000 live births in Western Europe. After birth the danger of infection is considerable. Also, the neural plaque dries out, with further damage to the nerves in the sac. These infants are therefore dealt with as acute emergencies and are operated within 48 hours (preferably 24 hours) after birth. Other major problems that spina bifida may present to the child are discussed, including hydrocephalus, urinary tract anomalies and orthopedic problems. Paralytic dislocation of the hips is the biggest problem and occurs in about one half of these children.peer-reviewe

Peutz Jeghers syndrome in childhood : report of a case

Peutz-Jeghers syndrome is a condition characterized by intestinal polyposis associated with typical pigmented spots around the mouth and on the oral mucosa. The syndrome is rare and to date about 300 cases have been reported in the world literature. It is much rarer in children than in adults. A case study of an 8-year-old boy with a 12 months history of recurrent episodes of anorexia, abdominal pain and vomiting is reported. The pain was colicky and localised to the epigastrium, usually coming on a few minutes after meals. On examination the boy looked pale and thin, weighing 41 lbs. He had numerous freckles on the face, especially on the nose and cheeks and around the mouth. The pigmentation extended over the vermilion of both lips and there were everal bluish-black pigmented spots on the labial and buccal mucosa. In diagnosis, it is usually the characteristic peri-oral and buccal pigmentation which suggests intestinal polyps as the basic cause of the patient's abdominal symptoms. In view of the decision to operate, the anemia was corrected by blood transfusion. The prognosis of the condition is, on the whole, good though these patients are prone to develop anemia from intestinal blood loss and have repeated episodes of intussusception from further polyps which tend to crop up in spurts over the years and which often require further surgical treatment.peer-reviewe

Purpura in the newborn

Generalised purpura is rare and of the many possible causes, perhaps the most common is thrombocytopenia associated with idiopathic thrombocytopenic purpura (I.T.P.) in the mother. One such case is presented in this study: The child was born from a 28-year old primigravida who in 1954, at the age of twelve years, had undergone splenectomy for I.T.P. On examination the male newborn had generalised purpura and areas of ecchymosis. The treatment provided to the neonate is described. Neonatal thrombocytopenia presents as generalized petechaie, purpuric spots and bleeding from various sites, e.g. melaena, haematuria and umbilical cord haemorrhage. In most cases no treatment is required as the condition is mild and resolves spontaneously. With severe thrombocytopenia, one must treat actively because of the threat of intracranial bleeding.peer-reviewe

Le programme Mogador en linguistique formelle arabe et ses applications dans le domaine de la recherche et du filtrage sémantique

The MOGADOR project aims at devolopping a new approach to Arabic Natural Langage Processing, by designing software tools based on an original description of Arabic grammar that gives top priority to its tool-words (in a redefined definition). These 'tool-words', that do not derivate from the standard morphological system, trigger off expectations at both syntactic and semantic levels, and thus constrain the sentence either locally or globally. Based on our theoretical and algorithmic work in morphological analysis, electronic dictionaries and proof software in corpora analysis and Information Retrieval, we plan to make available a new generation of filters featuring limited complexity. We propose steps in both theoretical and software fields, with the design of new parsers and software proof tools. These filters could be embedded in search tools boosting them with the results of new linguistic analysis, which have become essential considering the recent boom of the Arabic Web.Développer une approche nouvelle du traitement automatique de larabe fondés sur une modélisation originale de la grammaire arabe donnant la priorité aux mots-outils (redéfinis), est l'ambition du programme MOGADOR. Échappant au système de dérivation, ces mots-outils induisent des attentes syntaxiques voire sémantiques contraignant localement et/ou globalement la phrase. Forts de nos développements algorithmiques et applicatifs en analyse morphologique, en dictionnaires électroniques et en démonstrateurs dans le domaine de l'analyse de corpus et de la recherche d'informations, nous projetons, par des développements théoriques, la construction de nouveaux analyseurs et des mises en oeuvre concrètes, de rendre possibles de nouvelles méthodes de filtrage à complexité maîtrisée. Ces filtres pourront être couplés à des moteurs de recherche, dopant ces derniers par des analyses linguistiques qui sont devenues nécessaires depuis l'explosion du Web en langue arabe