In vitro activity of antimalarials against clinical isolates of Plasmodium falciparum in Yaounde, Cameroon

The in vitro activity of nine antimalarials was determined against 119 fresh clinical isolates of #Plasmodium falciparum$ obtained from symptomatic indigenous patients in Yaounde, Cameroun, using the isotopic semimicrotest. Seventy-four parasites were resistant to chloroquine (mean 50% inhibitory concentration [IC50] 337 nM) ; 45 were chloroquine-sensitive (mean IC50 35.6 nM). Twenty-five of 58 chloroquine-resistant parasites were resistant to monodesethylamodiaquine, the biologically active metabolite of amodiaquine. None of the chloroquine-sensitive isolates was resistant to monodesethylamodiaquine (IC50 17.3 nM). Pyronaridine, quinine, mefloquine, halofantrine, and artemether were highly active against the chloroquine-sensitive and the chloroquine-resistant isolates. Of the 43 isolates tested, 25 were sensitive to both pyrimethamine and cycloguanil, the biologically active metabolite of proguanil. The in vitro responses of chloroquine and monodesethylamodiaquine, chloroquine and quinine, quinine and mefloquine, mefloquine and halofantrine, artemether and mefloquine or halofantrine, and pyrimethamine and cycloguanil were significantly correlated. The present study suggests that chloroquine resistance is highly prevalent in vitro in Yaounde and that the alternative drugs are generally highly active against the chloroquine-resistant parasites. (Résumé d'auteur

General Statistical properties of the CMB Polarization field

The distribution of the polarization of the Cosmic Microwave Background (CMB) in the sky is determined by the hypothesis of random Gaussian distribution of the primordial density perturbations. This hypotheses is well motivated by the inflationary cosmology. Therefore, the test of consistency of the statistical properties of the CMB polarization field with the Gaussianity of primordial density fluctuations is a realistic way to study the nature of primordial inhomogeneities in the Universe. This paper contains the theoretical predictions of the general statistical properties of the CMB polarization field. All results obtained under assumption of the Gaussian nature of the signal. We pay the special attention to the following two problems. First, the classification and statistics of the singular points of the polarization field where polarization is equal to zero. Second, the topology of contours of the value of the degree of polarization. We have investigated the percolation properties for the zones of ``strong'' and ``weak'' polarization. We also have calculated Minkowski functionals for the CMB polarization field. All results are analytical.Comment: Latex, 22 pages, including 5 figure

Fuel Cell Testing Protocols: An International Perspective

An overview of international polymer-electrolyte fuel cell (PEMFC) test procedures is presented. This overview is the first step in the global harmonization of testing methods. Many techniques and procedures determining stack performance and durability are discussed. Each approach has differences that may or may not impact the data and data quality. Through experiments, it was found that differences in the results from two methods for measuring sequential polarization curves are minimal. Answers to questions regarding differences in the aging duty cycles need to be determined experimentally. The results of these experiments are expected to help the harmonization process, to facilitate the understanding of test results, and, possibly, to accelerate the commercialization of PEMFCs.JRC.F.2-Cleaner energ

Why and when do family firms invest less in talent management? The suppressor effect of risk aversion

none4siThis article explores the complex relationship between family firms and talent management practices. We use an international sample of medium-sized manufacturing firms to show that the relationship between family-owned firms and investment in talent management practices is mediated by the firm’s level of risk aversion, which is, in turn, moderated by industry competition. Risk-averse family-owned firms tend to invest less in talent management practices when industry competition is weak. In contrast, when competition increases, family-owned firms tend to invest in talent as much as non-family-owned firms do.openBasco, Rodrigo; Bassetti, Thomas; Dal Maso, Lorenzo; Lattanzi, NicolaBasco, Rodrigo; Bassetti, Thomas; Dal Maso, Lorenzo; Lattanzi, Nicol

Rozvoj osobnosti studenta na vysoké škole – francouzský model

Šance studentů uspět na vysoké škole jsou ovlivněny četnými faktory. Kulturní a socioekonomické rozdíly mezi jednotlivými studenty jsou značné. Je proto nutné vytvořit podmínky, které jim umožní osvojit si schopnosti nezbytné k úspěchu při studiu. V kontextu francouzské pedagogické reality zde nabízíme jednu z možností, jak pedagogicky podpořit rozvoj osobnosti studenta. Zkušenosti z Francie by mohly být přínosné i pro Českou republiku, která je nyní sice v jiné situaci, avšak směřuje k podobným změnám ve vysokoškolském vzdělávání, kterými v minulosti prošla Francie, tj. k rozšířenému přístupu k vysokoškolskému vzdělávání a k jeho opravdové demokratizaci, tedy i k nárůstu počtu vysokoškolských studentů

Stripes, Pseudogaps, and Van Hove Nesting in the Three-band tJ Model

Slave boson calculations have been carried out in the three-band tJ model for the high-T_c cuprates, with the inclusion of coupling to oxygen breathing mode phonons. Phonon-induced Van Hove nesting leads to a phase separation between a hole-doped domain and a (magnetic) domain near half filling, with long-range Coulomb forces limiting the separation to a nanoscopic scale. Strong correlation effects pin the Fermi level close to, but not precisely at the Van Hove singularity (VHS), which can enhance the tendency to phase separation. The resulting dispersions have been calculated, both in the uniform phases and in the phase separated regime. In the latter case, distinctly different dispersions are found for large, random domains and for regular (static) striped arrays, and a hypothetical form is presented for dynamic striped arrays. The doping dependence of the latter is found to provide an excellent description of photoemission and thermodynamic experiments on pseudogap formation in underdoped cuprates. In particular, the multiplicity of observed gaps is explained as a combination of flux phase plus charge density wave (CDW) gaps along with a superconducting gap. The largest gap is associated with VHS nesting. The apparent smooth evolution of this gap with doping masks a crossover from CDW-like effects near optimal doping to magnetic effects (flux phase) near half filling. A crossover from large Fermi surface to hole pockets with increased underdoping is found. In the weakly overdoped regime, the CDW undergoes a quantum phase transition ($T_{CDW}\to 0$), which could be obscured by phase separation.Comment: 15 pages, Latex, 18 PS figures Corrects a sign error: major changes, esp. in Sect. 3, Figs 1-4,6 replace

Sentinel network for monitoring in vitro susceptibility of Plasmodium falciparum to antimalarial drugs in Colombia: a proof of concept

Drug resistance is one of the principal obstacles blocking worldwide malaria control. In Colombia, malaria remains a major public health concern and drug-resistant parasites have been reported. In vitro drug susceptibility assays are a useful tool for monitoring the emergence and spread of drug-resistant Plasmodium falciparum. The present study was conducted as a proof of concept for an antimalarial drug resistance surveillance network based on in vitro susceptibility testing in Colombia. Sentinel laboratories were set up in three malaria endemic areas. The enzyme linked immunosorbent assay-histidine rich protein 2 and schizont maturation methods were used to assess the susceptibility of fresh P. falciparum isolates to six antimalarial drugs. This study demonstrates that an antimalarial drug resistance surveillance network based on in vitro methods is feasible in the field with the participation of a research institute, local health institutions and universities. It could also serve as a model for a regional surveillance network. Preliminary susceptibility results showed widespread chloroquine resistance, which was consistent with previous reports for the Pacific region. However, high susceptibility to dihydroartemisinin and lumefantrine compounds, currently used for treatment in the country, was also reported. The implementation process identified critical points and opportunities for the improvement of network sustainability strategies.PAHO [057-1-3144141]; COLCIENCIAS [ID 2229-405-20319]info:eu-repo/semantics/publishedVersio