Range Grasses of Hawaii

This bulletin discusses the more important grasses growing on local ranges, their growth in other parts of the world, nature of growth, palatability, persistence, climatic requirements, and present importance and possibilities for Hawaii

Le paludisme urbain à Yaoundé (Cameroun) : 2. Etude entomologique dans deux quartiers peu urbanisés

International audienceA one year entomological survey was carried out to precise the malaria vectors and the malaria transmission in Yaounde, the Cameroon capital (800,000 inhabitants). The study was done in two districts not yet fully urbanized: Nkol Bikok and Nkol Bisson. The latter is located at the periphery and has a pool. Anopheles gambiae was the only human malaria vector. Its agressivity for man depended on the urbanization of the district. Annual man biting rate was 284 in Nkol Bikok and 1,813 in Nkol Bisson. The densities were maximum in May-June and in October-November, corresponding to the end of the short and long rainy seasons. The presence of A. gambiae was permanent except in August-September in Nkol Bikok. In Nkol Bisson the density was higher in the houses near the pool. The yearly inoculation rate (h) was 14 in Nkol Bikok and 30 in Nkol Bisson. The vectorial transmission was observed in may in Nkol Bikok and during four months (June, August, January, February) in Nkol Bisson. These entomological data showed clearly that malaria transmission actually occurred in Yaounde and that the probability to receive at least one infected anopheline bite per year was very near to 1 for inhabitants unprotected against mosquito bites.Une étude longitudinale basée sur la capture des moustiques sur sujets humains s'est déroulée pendant un an dans deux quartiers de la ville de Yaoundé, l'un est situé à la périphérie de la ville (Nkol Bisson) et l'autre est plus central (Nkol Bikok). Ces deux quartiers présentent encore un caractère périurbain mais ils sont en pleine urbanisation. Le vecteur du paludisme humain identifé est Anopheles gambiae. Sa densité agressive pour l'homme (ma) est variable selon le degré d'urbanisation des quartiers : forte en Zone périphérique (ma annuel = I 813) et faible en zone centrale (ma annuel = 284). Cette densité est importante de mai à juin et d'octobre 6 novembre, c'est-à-dire à la fin de la petite et de la grande saison des pluies. Le taux d'inoculation (h) varie comme les densités agressives : h annuel = 30 en zone périphérique contre 14 en zone centrale. La transmission vectorielle est notable seulement pendant un mois (mai) à Nkol Bikok et pendant quatre mois (juin, août, janvier, février) à Nkol Bisson. Le risque quotidien d'au moins une inoculation par A. gambiae est environ deux fois plus élevé en zone périphérique qu'en zone centrale

Anthropophilic mosquitoes and malaria transmission at Edea, Cameroon

International audienceAn entomological study was carried out during 1990 in the town of Edea in the south of Cameroon to study anthropophilic mosquitoes with special reference to malaria transmission. Man-biting mosquitoes were caught regularly during one night each month in two different districts: Bilalang which is a well planned suburb with 160 houses on a hill-top, provided with a piped water supply; and Pongo which is a densely urbanised suburb in a valley. From 188 man-nights 1030 mosquitoes were collected, comprising 700 Culex quinquefasciatus (68%), 262 Anopheles gambiae (25%) and others species (7%) belonging to the genus Anopheles, Mansonia, Culex and Aedes. The estimated annual biting rates of mosquitoes were 811 bites per man in Bilalang and 2,866 in Pongo. The estimated yearly malaria inoculation rates were 3.8 and 30.2 infective bites per man in Bilalang and Pongo, respectively. In different parts of Pongo district much variation existed; extreme values of the estimated yearly inoculation rate were zero and 86.3 in two houses 200 m apart, located on the top of a hill and in the bottom of a valley, respectively. This study is one of the first conducted on malaria transmission in a moderate sized African town; it shows that the mosquito populations are typically urban and differ greatly from rural ones

A neutron scattering study of two-magnon states in the quantum magnet copper nitrate

We report measurements of the two-magnon states in a dimerized antiferromagnetic chain material, copper nitrate (Cu(NO3)2*2.5D2O). Using inelastic neutron scattering we have measured the one and two magnon excitation spectra in a large single crystal. The data are in excellent agreement with a perturbative expansion of the alternating Heisenberg Hamiltonian from the strongly dimerized limit. The expansion predicts a two-magnon bound state for q ~ (2n+1)pi*d which is consistent with the neutron scattering data.Comment: 11 pages of revtex style with 6 figures include

Large enhancement of deuteron polarization with frequency modulated microwaves

We report a large enhancement of 1.7 in deuteron polarization up to values of 0.6 due to frequency modulation of the polarizing microwaves in a two liters polarized target using the method of dynamic nuclear polarization. This target was used during a deep inelastic polarized muon-deuteron scattering experiment at CERN. Measurements of the electron paramagnetic resonance absorption spectra show that frequency modulation gives rise to additional microwave absorption in the spectral wings. Although these results are not understood theoretically, they may provide a useful testing ground for the deeper understanding of dynamic nuclear polarization.Comment: 10 pages, including the figures coming in uuencoded compressed tar files in poltar.uu, which also brings cernart.sty and crna12.sty files neede

Azimuthal asymmetries of charged hadrons produced by high-energy muons scattered off longitudinally polarised deuterons

Azimuthal asymmetries in semi-inclusive production of positive (h^+) and negative hadrons (h^-) have been measured by scattering 160 GeV muons off longitudinally polarised deuterons at CERN. The asymmetries were decomposed in several terms according to their expected modulation in the azimuthal angle phi of the outgoing hadron. Each term receives contributions from one or several spin and transverse-momentum-dependent parton distribution and fragmentation functions. The amplitudes of all phi-modulation terms of the hadron asymmetries integrated over the kinematic variables are found to be consistent with zero within statistical errors, while the constant terms are nonzero and equal for h^+ and h^- within the statistical errors. The dependencies of the phi-modulated terms versus the Bjorken momentum fraction x, the hadron fractional momentum z, and the hadron transverse momentum p_h^T were studied. The x dependence of the constant terms for both positive and negative hadrons is in agreement with the longitudinal double-spin hadron asymmetries, measured in semi-inclusive deep-inelastic scattering. The x dependence of the sin phi-modulation term is less pronounced than that in the corresponding HERMES data. All other dependencies of the phi-modulation amplitudes are consistent with zero within the statistical errors.Comment: 12 pages, 11 Figures; revision 1 signs in Eq 5 corrected, polishe

An Observational Overview of Solar Flares

We present an overview of solar flares and associated phenomena, drawing upon a wide range of observational data primarily from the RHESSI era. Following an introductory discussion and overview of the status of observational capabilities, the article is split into topical sections which deal with different areas of flare phenomena (footpoints and ribbons, coronal sources, relationship to coronal mass ejections) and their interconnections. We also discuss flare soft X-ray spectroscopy and the energetics of the process. The emphasis is to describe the observations from multiple points of view, while bearing in mind the models that link them to each other and to theory. The present theoretical and observational understanding of solar flares is far from complete, so we conclude with a brief discussion of models, and a list of missing but important observations.Comment: This is an article for a monograph on the physics of solar flares, inspired by RHESSI observations. The individual articles are to appear in Space Science Reviews (2011