Caractéristiques phénotypique et structurale de la population de Parkia biglobosa (Jacq.) R. Br. du Nord-Bénin

La présente étude a pour objectif principal d’identifier les caractéristiques phénotypiques et structurales des sous-populations de Parkia biglobosa (néré) du Nord-Bénin, en vue d’une gestion durable de l’espèce. Cinq cent quatre vingt seize arbres de néré ont été échantillonnés. Les principaux résultats ont montré qu’il existe quatre sous-populations de néré dans le milieu d’étude. Les huit descripteurs quantitatifs étudiés sur l’espèce (nombre de rachis par feuille, nombre de gousses par infrutescence, longueur du pédoncule, épaisseur du pédoncule, longueur du pédicelle de la gousse, longueur de la gousse, poids de la gousse, nombre de graines par gousse) varient d’une sous-population à une autre, alors que les paramètres dendrométriques varient très peu. L’étude de la structure diamétrique des différentes sous-populations a montré que l’espèce connait un problème de régénération. En ce qui concerne l’importance pratique de ce travail, notons que l’aspect du néré le plus recherché est sa production fruitière. Les pieds de néré de la sous-population Kalalé présentent des valeurs moyennes élevées de poids de gousse, de nombre de graines par gousse et de nombre de gousses par infrutescence. Ils sont particulièrement intéressants et peuvent être pris en compte dans le cadre d’une sélection de variétés à haut rendement.Mots clés : Sous-population, Parkia biglobosa, phénotype, structure, Nord-Béni

Decay Properties of 266^{266}Bh and 262^{262}Db Produced in the 248^{248}Cm + 23^{23}Na Reaction

Decay properties of an isotope $^{266}$Bh and its daughter nucleus $^{262}$Db produced by the $^{248}$Cm($^{23}$Na, 5\textit{n}) reaction were studied by using a gas-filled recoil separator coupled with a position-sensitive semiconductor detector. $^{266}$Bh was clearly identified from the correlation of the known nuclide, $^{262}$Db. The obtained decay properties of $^{266}$Bh and $^{262}$Db are consistent with those observed in the $^{278}$113 chain, which provided further confirmation of the discovery of $^{278}$113.Comment: Accepted for publication in J. Phys. Soc. JPN., to be published in Vol.78 No.

A Comparative Study of Perceived Stress among Female Medical and Non-Medical University Students in Dammam, Saudi Arabia

Objectives: The objective of this study was to investigate any differences between female undergraduate medical and non-medical students for: 1) prevalence and causes of perceived academic stress, and 2) changes in physical, mental, psychological and emotional health as well as life-style since starting college studies. Methods: A cross-sectional study was conducted at Dammam University, Dammam, Saudi Arabia, in January 2008. All 319 pre-clinical female medical students were included in the study and 297 non-medical students from the College of Applied Studies and Community Services (CASCS) were selected by stratified random sampling. The study instrument was a questionnaire on the “Influence of Studying on Students’ Health”. Results: More medical students (48.6%) reported being frequently stressed due to studies than CASCS students (38.7%, P <0.01). Unsuitable teaching methods, an unsatisfactory study environment, and fear of failure in examinations were more frequently mentioned by medical than non-medical students (P <0.05). While underlying social problems were significantly more common in medical students, economic problems were more prevalent among CASCS students (P <0.05, P <0.05). More medical than non-medical students reported a worse status of physical and mental health, anxiety and depression and negative life-style changes since initiation of the college programme. Conclusion: Medical students were at higher risk of physical and mental health problems than non-medical students due to academic stress. Since a substantial proportion of CASCS students also experienced academic stress, we recommend that a student support committee be established for both colleges to provide counselling and guidance in healthy ways to cope with stress

Pionic Atom Spectroscopy in the (d,3He) reaction at finite angles

We study the formation of deeply bound pionic atoms in the (d,3He) reactions theoretically and show the energy spectra of the emitted 3He at finite angles, which are expected to be observed experimentally. We find that the different combinations of the pion-bound and neutron-hole states dominate the spectra at different scattering angles because of the matching condition of the reaction. We conclude that the observation of the (d,3He) reaction at finite angles will provide the systematic information of the pionic bound states in each nucleus and will help to develop the study of the pion properties and the partial restoration of chiral symmetry in nuclei.Comment: 7 pages, 4 figures, 1 tabl

Application of First-Principles-Based Artificial Neural Network Potentials to Multiscale-Shock Dynamics Simulations on Solid Materials

The use of artificial neural network (ANN) potentials trained with first-principles calculations has emerged as a promising approach for molecular dynamics (MD) simulations encompassing large space and time scales while retaining first-principles accuracy. To date, however, the application of ANN-MD has been limited to near-equilibrium processes. Here we combine first-principles-trained ANN-MD with multiscale shock theory (MSST) to successfully describe far-from-equilibrium shock phenomena. Our ANN-MSST-MD approach describes shock-wave propagation in solids with first-principles accuracy but a 5000 times shorter computing time. Accordingly, ANN-MD-MSST was able to resolve fine, long-time elastic deformation at low shock speed, which was impossible with first-principles MD because of the high computational cost. This work thus lays a foundation of ANN-MD simulation to study a wide range of far-from-equilibrium processes

Inducible nitric oxide synthase (iNOS) expression may predict distant metastasis in human melanoma

Expression of inducible nitric oxide synthase (iNOS) and its cellular localization was investigated in subcutaneous or lymph node metastases of human melanoma. Immunohistochemistry revealed that iNOS expression was limited to melanoma cells. In samples of patients without distant metastases, the number of iNOS+ tumour cells/total tumour cells was 55% ± 17% (n = 12) compared with 9% ± 8% when distant metastases of lung, liver or brain occurred within an observation period of 3 years (n = 10) (P < 0.001). Western blotting confirmed the expression of iNOS protein in select cases. Notably, iNOS is expressed in regional melanoma metastases and its expression is inversely related to the tumour's metastatic potential. Thus, iNOS expression may have predictive value for the development of distant metastases of human melanoma. © 1999 Cancer Research Campaig

Decay modes of 250No

The Fragment Mass Analyzer at the ATLAS facility has been used to unambiguously identify the mass number associated with different decay modes of the nobelium isotopes produced via 204Pb(48Ca,xn)(252-x)No reactions. Isotopically pure (>99.7%) 204Pb targets were used to reduce background from more favored reactions on heavier lead isotopes. Two spontaneous fission half-lives (t_1/2 = 3.7+1.1-0.8 us and 43+22-15 us) were deduced from a total of 158 fission events. Both decays originate from 250No rather than from neighboring isotopes as previously suggested. The longer activity most likely corresponds to a K-isomer in this nucleus. No conclusive evidence for an alpha branch was observed, resulting in upper limits of 2.1% for the shorter lifetime and 3.4% for the longer activity.Comment: RevTex4, 10 pages, 5 figures, submitted to PR

Optimal design of multi-channel microreactor for uniform residence time distribution

Multi-channel microreactors can be used for various applications that require chemical or electrochemical reactions in either liquid, gaseous or multi phase. For an optimal control of the chemical reactions, one key parameter for the design of such microreactors is the residence time distribution of the fluid, which should be as uniform as possible in the series of microchannels that make up the core of the reactor. Based on simplifying assumptions, an analytical model is proposed for optimizing the design of the collecting and distributing channels which supply the series of rectangular microchannels of the reactor, in the case of liquid flows. The accuracy of this analytical approach is discussed after comparison with CFD simulations and hybrid analytical-CFD calculations that allow an improved refinement of the meshing in the most complex zones of the flow. The analytical model is then extended to the case of microchannels with other cross-sections (trapezoidal or circular segment) and to gaseous flows, in the continuum and slip flow regimes. In the latter case, the model is based on second-order slip flow boundary conditions, and takes into account the compressibility as well as the rarefaction of the gas flow

New Features in the Computational Infrastructure for Nuclear Astrophysics

A Computational Infrastructure for Nuclear Astrophysics has been developed to streamline the inclusion of the latest nuclear physics data in astrophysics simulations. The infrastructure consists of a platform-independent suite of computer codes that are freely available online at http://nucastrodata.org. The newest features of, and future plans for, this software suite are given. © Copyright owned by the author(s)