Variations altitudinale et saisonnière de l’abondance de deux crevettes Atyidae dans les cours d’eau du mont Simandou (Guinée)

Les crevettes Caridinopsis chevalieri Bouvier, 1912 et Caridina africana Kingsley, 1883 sont les plus rencontrées dans les cours d’eau du mont Simandou (Guinée). Les variations altitudinale et saisonnière de leur abondance sont discutées dans la présente étude. Deux campagnes d’échantillonnage (saisons sèche et pluvieuse) ont été effectuées sur 27 sites en 2011. Des paramètres physico-chimiques ont été mesurés avant l’échantillonnage des crevettes en vue de la caractérisation du milieu. Au total, 323 individus de crevettes dont 57% de C. chevalieri et 43% de C. africana ont été collectés. En basse altitude (< 650m), la population est dominée par C. africana (79%). Par contre, en haute altitude (> 650m), C. chevalieri est le plus abondant (71%). C. chevalieri est plus rencontré en saison sèche alors que C. africana prédomine la population en saison des pluies. La conductivité, la température, le pH, la vitesse du courant et le type d’habitat sont les principaux paramètres du milieu qui influencent la distribution spatio-temporelle de l’abondance des deux espèces étudiées. Cette étude présente les données préliminaires sur les crevettes du mont Simandou et constitue une base importante pour des études futures sur la diversité et l’écologie de faune de crustacés de cette zone.Mots clés: Crevette, Caridina africana, Caridinopsis chevalieri, abondance, Mont SimandouEnglish Title: Altitudinal and seasonal variations in the abundance of two Atyidae shrimps in the streams of Mount Simandou (Guinea)English AbstractThe shrimp Caridinopsis chevalieri Bouvier, 1912 and Caridina africana Kingsley, 1883 are the most encountered in the rivers of the Simandou Mountain (Guinea). The altitudinal and seasonal variations in abundance of both species are discussed in this study. Two sampling campaigns (dry and rainy season) were conducted at 27 sites during year 2011. Some physical and chemical parameters were measured before sampling shrimp in order to the characterization of the environment. A total of 323 individuals of shrimp comprising 57% of C. chevalieri and 43% C. africana were collected. In low altitude (<650m), the population is dominated by C. africana. (79%). On the other hand, at high altitude (> 650m), C. chevalieri is the most abundant (71%). C. chevalieri is most sampled during the dry season while C. africana dominates shrimp population in the rainy season. The conductivity, temperature, pH, dissolved oxygen and the type of habitat are the main environmental parameters that influence the spatial and temporal distribution of the abundance of the two studied species. This research presents preliminary data on shrimp from Simandou Mountain and is an important basis for future studies on diversity and ecology of crustacean from this area.Keywords: Shrimp, Caridina africana, Caridinopsis chevalieri, abundance, Simandou Mountai

The Polygenic and Monogenic Basis of Blood Traits and Diseases

Blood cells play essential roles in human health, underpinning physiological processes such as immunity, oxygen transport, and clotting, which when perturbed cause a significant global health burden. Here we integrate data from UK Biobank and a large-scale international collaborative effort, including data for 563,085 European ancestry participants, and discover 5,106 new genetic variants independently associated with 29 blood cell phenotypes covering a range of variation impacting hematopoiesis. We holistically characterize the genetic architecture of hematopoiesis, assess the relevance of the omnigenic model to blood cell phenotypes, delineate relevant hematopoietic cell states influenced by regulatory genetic variants and gene networks, identify novel splice-altering variants mediating the associations, and assess the polygenic prediction potential for blood traits and clinical disorders at the interface of complex and Mendelian genetics. These results show the power of large-scale blood cell trait GWAS to interrogate clinically meaningful variants across a wide allelic spectrum of human variation. Analysis of blood cell traits in the UK Biobank and other cohorts illuminates the full genetic architecture of hematopoietic phenotypes, with evidence supporting the omnigenic model for complex traits and linking polygenic burden with monogenic blood diseases

High-K,t1/2=1.4(1) ms, isomeric state in Lr255

An isomeric state in Lr255 with a half-life of t1/2=1.4(1) ms and Ex>720-keV has been observed for the first time using the GABRIELA setup at the focal plane of the VASSILISSA separator. Based on its K-forbiddeness, the configuration of the state is most probably formed by coupling the valence proton to a two quasiparticle neutron excitation. Possible three quasiparticle configurations are discussed. © 2008 The American Physical Society.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Detailed spectroscopy in 249^{249}Fm

Excited states in 249Fm were populated via the alpha decay of 253No and the subsequent decay was observed with the GABRIELA detection system installed at the focal plane of the VASSILISSA recoil separator. The energies, spins, and parities of these states could be established through combined alpha, gamma, and conversion-electron spectroscopy. The first members of the ground-state rotational band were identified. Their excitation energies as well as the observation of a cross-over E2 transition confirm the assignment of 7/2+[624] for the ground state of 249Fm. Two excited states were also observed and their decay properties suggest that they correspond to the particle excitation 9/2-[734] and hole excitation 5/2+[622]. The analysis suggests that the 279-keV transition de-exciting the 9/2- state has anomalous E1 conversion coefficients

Gamma and electron spectroscopy of heavy nuclei at FLNR JINR

Detailed spectroscopic information of excited nuclear states in deformed transfermium nuclei is scarce. Most of the information available today has been obtained from investigations of fine structure α decay. Although α decay gives access to hindrance factors and lifetimes which are strongly correlated to shell/subshell closures and the presence of isomers, only the combined use of γ and conversion electron spectroscopy allows the precise determination of excitation energy, spin and parity of nuclear levels. In particular, the study of odd isotopes gives crucial information on the single particle states available at and around the Fermi surface. In the following, the preliminary results of decay studies using α - γ and α - beta coincidences at the focal plane of the VASSILISSA recoil separator are presented. © 2007 American Institute of Physics.SCOPUS: cp.pinfo:eu-repo/semantics/publishe

Isomeric states in 253No

Isomeric states in 253No have been investigated by conversion electron and γ -ray spectroscopy with the GABRIELA detection system. The 31μs isomer reported more than 30 years ago is found to decay to the ground state of 253No by the emission of a 167keV M2 transition. The spin and parity of this low-lying isomeric state are established to be 5/2 + .The presence of another longer-lived isomeric state is also discussed. © Società Italiana di Fisica and Springer-Verlag 2007.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Spectroscopy of heavy elements at Dubna

In 2004, the GABRIELA (Gamma Alpha Beta Recoil Investigation with the Electromagnetic Analyzer VASSILISSA) collaboration started a twofold scientific program at the FLNR (Dubna) laboratory: (a) the systematic study of the behaviour of single particle states within isotopic and isotonic chains with Z = 100-104 as N varies from 152 to 162 and (b) the study of isotopes for which very little spectroscopic information is known. After discussing the Physics motivations and the experimental setup, some new results concerning the structure of 249Fm and 253No nuclei, and some preliminary results on the decay of 217Pa decay are presented.SCOPUS: cp.pinfo:eu-repo/semantics/publishe