Biotic and abiotic factors influencing the mangrove vegetation of Qaoqiang (Guangdong, China): a first approach

The present ongoing MSc study is carried out in south-western China, in a mangrove managed by the Zhanjiang Mangrove National Natural Reserve (ZMNNR). The ZMNNR covers approximately 20,000ha of naturally established mangrove forest, mangrove plantations, inter-tidal sand and mud flats, river channels and streams. The reserve has been classified in 2002 as a wetland of national importance by the Ramsar Convention for its biodiversity, for the goods and services provided to the population and also as a bird refuge of great importance. However, this area is still relatively unknown, and not much phytosociological studies were carried out there. The mangrove we are studying is located in the County of Lianjiang: an enclave in the Beibu Gulf, at 4.5km to the southwest of the town of Gaoqiao. The Gaoqiao mangrove is the most important wetland area managed by the ZMNNR. The aim of this study is to understand and analyse the structure of the vegetation in terms of floristic diversity, biomass, density and height of the trees based on nine transects with a total of 210 sampled points. The structure of the vegetation will be determined with beta diversity index, biomass, height and basal area of trees for each of the sampling point. Then we will apply a multivariate analysis (ordination, cluster and statistical analysis) to find which of the selected environmental factors can explain the most part of the vegetation. Each analysis will be done for two phytosociological methods: a plot-based method and a plot-less method. We will test the relationship between these sampling methods to find an appropriate compromise between accuracy and time spent on it. Other observations were also made in this newly studied mangrove. New researches will be done soon on the parasitism of mangrove trees by barnacles and caterpillars, on the invasion of exotic introduced species, on fishing impact, aquaculture and rice culture, on the climate impacts and on the importance of the rivers network on the vegetation structure and dynamics

Prognostic implications of mean nuclear diameter in breast cancer.

The mean nuclear diameter of 100 breast cancers was measured on tissue sections, to evaluate its importance for early prognosis. The cases were subdivided into 3 subgroups: small (25.5% of cases), medium (63.3%) and large (11.2%) nuclei. Early recurrence and mortality rates were investigated in each of the categories. Increasing nuclear size was shown to be related to mortality from metastatic disease. However, large-nucleus tumours had an inverse relationship with lymphnode involvement and possibly with recurrence rate. Hence, in our material nuclear size as a sole criterion was not a good indicator of the early behaviour of operable breast cancer

Low energy measurement of the 7Be(p,gamma)8B cross section

We have measured the cross section of the 7Be(p,gamma)8B reaction for E_cm = 185.8 keV, 134.7 keV and 111.7 keV using a radioactive 7Be target (132 mCi). Single and coincidence spectra of beta^+ and alpha particles from 8B and 8Be^* decay, respectively, were measured using a large acceptance spectrometer. The zero energy S factor inferred from these data is 18.5 +/- 2.4 eV b and a weighted mean value of 18.8 +/- 1.7 eV b (theoretical uncertainty included) is deduced when combining this value with our previous results at higher energies.Comment: Accepted for publication in Phys. Rev. Let

Analyse de la distribution spatiale des Acanthaceae en Afrique Centrale et comparaison avec les théories phytogéographiques de Robyns, White et Ndjele.

Cette étude a pour but d\'analyser les modèles de distribution spatiale des Acanthaceae, récoltées en République Démocratique du Congo, au Rwanda et au Burundi et de comparer leur répartition spatiale avec les systèmes phytogéographiques qui couvrent cette zone. Elle porte sur 9181 échantillons regroupés en 48 genres et 310 espèces. Un système d\'information géographique a été utilisé pour réaliser des cartes de distribution de chaque espèce. La méthode multi variée de classification, appuyée par deux indices de structure spatiale (équitabilité et fragmentation) a permis de stratifier la zone d\'étude afin de permettre une comparaison visuelle avec les systèmes phytogéographiques définis par Robyns, White et Ndjele. On note une large distribution spatiale pour certaines espèces sur l\'ensemble du territoire, alors que d\'autres sont inféodées à certains territoires phytogéographiques bien déterminés. Les savanes situées au Sud de l\'équateur contiennent des sites plus riches en Acanthaceae que celles situées au Nord. Les centres d\'endémisme Guinéo-Congolais, Zambézien et Afromontagnard pourraient être les sources de migration des taxons. Les Acanthaceae suivent relativement bien le système phytogéographique de White et sont utilisables en tant que bioindicatrices afin de rapprocher la distribution spatiale des communautés végétales décrites par ce système.By means of 9181 samples representing 48 genus and 310 species, the spatial distribution models of the Acanthaceae family in Central Africa (Democratic Republic of Congo, Rwanda and Burundi) were analysed. Consequently, a comparison to existing phytogeographic systems for the study region was executed. Spatial distribution maps for each species were created using a geographic information system. Subdivision of the study area was realised using a multivariate classification analysis. Using two indices of spatial pattern (fragmentation, class size evenness), the classification result was compared to the phytogeographic zones defined by Robyns, White and Ndjele. While certain species showed a distribution throughout the study area, the presence of other species was found to be bound to one single phytogeographic territory in particular, or to a restricted number of them. The savannas situated in the southern part of the study area contained more Acanthaceae species than the zones situated north of the equator. The Guineo-Congolian, the Zambezian and the Afromontane centre of endemism are suggested to be the origins of taxon migration. Since it was observed that the spatial pattern of the Acanthaceae species corresponded up a certain extent to the phytogeographic system proposed by White, it can be concluded that the Acanthaceae could be used as bio-indicators to proxy the spatial distribution of plant communities as described by this system. Keywords: phytogeography, spatial analysis, Acanthaceae, Central Africa, district, sector.Sciences & Nature Vol. 5 (2) 2008: pp. 101-11

Effets de lisière et sex-ratio de rongeurs forestiers dans un écosystème fragmenté en République Démocratique du Congo (Réserve de Masako, Kisangani)

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