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Michez D.,University of Mons | Eardley C.,Agricultural Research Council | Eardley C.,University of KwaZulu - Natal | Kuhlmann M.,Natural History Museum in London | And 2 more authors.
Invertebrate Systematics | Year: 2010

Recent molecular phylogenetic data showed the Melittidae as the likely sister group to all other bees and indicated that proto-melittids could have been host-plant specialists originating in Africa. However, robust phylogenetic data at generic and species level are now needed for all melittid clades to test these hypotheses and investigate early melittid and bee evolution in general. The bee genera Haplomelitta and Samba, which comprise the former tribe Sambini (Hymenoptera:Melittidae), are revised here. The genera are endemic to the Afrotropical region, occurring in eastern and southern Africa. Previous studies hypothesised that Samba rendered Haplomelitta paraphyletic but a conclusive taxonomic decision was not proposed. By performing a comprehensive phylogenetic analysis based on five nuclear genes (28S, CAD, EF-1 (F2 copy), long-wavelength rhodopsin (opsin) and RNA polymerase II (RNAp); total 4179bp) and morphological characters (34 characters), we here synonymise Haplomelitta with Samba. The genus is now subdivided into six subgenera containing 10 species, four of which are here described as new, namely: S. ascheri, S. gessorum, S. spinosa and S. rubigoinis. Moreover, we also considered biogeography, phenology and floral visitation data. Samba seems to have originated in southern Africa and later colonised eastern Africa. The ancestral host-plant foraging strategy was probably specialisation on one plant family (e.g. oligolectism). This result supports the hypothesis that the ancestor of bees arose in Africa and was a host-plant specialist. © CSIRO. Source

Impellizzeri G.,CNR Institute for Microelectronics and Microsystems | Boninelli S.,CNR Institute for Microelectronics and Microsystems | Priolo F.,CNR Institute for Microelectronics and Microsystems | Napolitani E.,CNR Institute for Microelectronics and Microsystems | And 3 more authors.
Journal of Applied Physics | Year: 2011

The enhanced diffusion of donor atoms, via a vacancy (V)-mechanism, severely affects the realization of ultrahigh doped regions in miniaturized germanium (Ge) based devices. In this work, we report a study about the effect of fluorine (F) on the diffusion of arsenic (As) in Ge and give insights on the physical mechanisms involved. With these aims we employed experiments in Ge co-implanted with F and As and density functional theory calculations. We demonstrate that the implantation of F enriches the Ge matrix in V, causing an enhanced diffusion of As within the layer amorphized by F and As implantation and subsequently regrown by solid phase epitaxy. Next to the end-of-range damaged region F forms complexes with Ge interstitials, that act as sinks for V and induce an abrupt suppression of As diffusion. The interaction of Ge interstitials with fluorine interstitials is confirmed by theoretical calculations. Finally, we prove that a possible F-As chemical interaction does not play any significant role on dopant diffusion. These results can be applied to realize abrupt ultra-shallow n-type doped regions in future generation of Ge-based devices. © 2011 American Institute of Physics. Source

Neeraja C.,University of Hyderabad | Anil K.,University of Hyderabad | Purushotham P.,University of Hyderabad | Suma K.,University of Hyderabad | And 3 more authors.
Critical Reviews in Biotechnology | Year: 2010

Fungal diseases of plants continue to contribute to heavy crop losses in spite of the best control efforts of plant pathologists. Breeding for disease-resistant varieties and the application of synthetic chemical fungicides are the most widely accepted approaches in plant disease management. An alternative approach to avoid the undesired effects of chemical control could be biological control using antifungal bacteria that exhibit a direct action against fungal pathogens. Several biocontrol agents, with specific fungal targets, have been registered and released in the commercial market with different fungal pathogens as targets. However, these have not yet achieved their full commercial potential due to the inherent limitations in the use of living organisms, such as relatively short shelf life of the products and inconsistent performance in the field. Different mechanisms of action have been identified in microbial biocontrol of fungal plant diseases including competition for space or nutrients, production of antifungal metabolites, and secretion of hydrolytic enzymes such as chitinases and glucanases. This review focuses on the bacterial chitinases that hydrolyze the chitinous fungal cell wall, which is the most important targeted structural component of fungal pathogens. The application of the hydrolytic enzyme preparations, devoid of live bacteria, could be more efficacious in fungal control strategies. This approach, however, is still in its infancy, due to prohibitive production costs. Here, we critically examine available sources of bacterial chitinases and the approaches to improve enzymatic properties using biotechnological tools. We project that the combination of microbial and recombinant DNA technologies will yield more effective environment-friendly products of bacterial chitinases to control fungal diseases of crops. © 2010 Informa Healthcare USA, Inc. Source

Bittner A.,Hospital of the University of Mnster | Bittner A.,University of Chile | Mnnig G.,Hospital of the University of Mnster | Vagt A.J.,Hospital of the University of Mnster | And 8 more authors.
Europace | Year: 2011

Aims: : Pulmonary veins (PV) play a pivotal role in atrial fibrillation (AF). Anatomical variants of PV have been described and related to a higher arrhythmogenic potential. The aim of this study was to compare the prevalence of PV variants and diameters of PV ostia in AF patients and controls. Methods and results: : Variants of PV were defined as right or left common ostia (RCO, LCO), a right middle or right top PV. A long common trunk (LCT) was defined as an LCO with a distance to the first branching <10 mm. Multislice contrast-enhanced thoracic computed tomography was performed prior to AF ablation in 166 consecutive patients, 47.6 with paroxysmal, 52.4 with persistent AF, as well as in a sex- and age-matched control group without AF, for non-cardiological indications. Images were evaluated by two independent observers. The mean age was 59 ± 10 years, 108 were men (65.1). A higher prevalence of LCO was found in the AF group: 33.7 vs. 19.9 (P 0.004), odds ratio (OR) 2.1; 15.4 in patients vs. 10.2 in controls had an LCT (P 0.14). No differences in other PV variants were found. The ostial diameters were greater in AF-patients (P< 0.001). Conclusion: s: To the best of our knowledge, the present study shows for the first time a higher prevalence of an LCO in patients with AF as compared with controls, with an OR of 2.1. This suggests a pre-disposing role of LCO in the development of AF. Published on behalf of the European Society of Cardiology. All rights reserved. © 2011 The Author. Source

Prall M.,University of Mnster
Progress in Particle and Nuclear Physics | Year: 2011

The KArlsruhe TRItium Neutrino experiment, KATRIN[21] will determine the mass of the ν̄e with a sensitivity of 0.2 eV (90% C.L.) via a measurement of the β-spectrum of gaseous tritium near its endpoint of 18.57 keV. An ultra-low background of a few mHz and an energy resolution of 0.93 eV are among the requirements to reach the sensitivity. These demands are fulfilled with the main spectrometer being of the MAC-E filter type and which is equipped with a 650m2, two-layered and quasi-massless wire electrode presented in this article. We also report on a recent background related test experiment: the investigation of the possibility to reduce the retarding voltage of the pre-spectrometer in order to diminish a Penning trap leading to increased background. © 2011 Elsevier B.V. All rights reserved. Source

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