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101.
Daniel?BeckerEmail author Markus?Geimer Rolf?Rabenseifner Felix?Wolf 《Cluster computing》2013,16(1):171-189
Event traces are helpful in understanding the performance behavior of parallel applications since they allow the in-depth analysis of communication and synchronization patterns. However, the absence of synchronized clocks on most cluster systems may render the analysis ineffective because inaccurate relative event timings may misrepresent the logical event order and lead to errors when quantifying the impact of certain behaviors or confuse the users of time-line visualization tools by showing messages flowing backward in time. In our earlier work, we have developed a scalable algorithm called the controlled logical clock that eliminates inconsistent inter-process timings postmortem in traces of pure MPI applications, potentially running on large processor configurations. In this paper, we first demonstrate that our algorithm also proves beneficial in computational grids, where a single application is executed using the combined computational power of several geographically dispersed clusters. Second, we present an extended version of the algorithm that—in addition to message-passing event semantics—also preserves and restores shared-memory event semantics, enabling the correction of traces from hybrid applications. 相似文献
102.
Sara Borin Francesca Mapelli Eleonora Rolli Bongkeun Song Craig Tobias Markus C. Schmid Gert J. De Lange Gert J. Reichart Stefan Schouten Mike Jetten Daniele Daffonchio 《Extremophiles : life under extreme conditions》2013,17(2):289-299
To extend the knowledge of anaerobic ammonium oxidation (anammox) habitats, bacterial communities were examined in two hypersaline sulphidic basins in Eastern Mediterranean Sea. The 2 m thick seawater–brine haloclines of the deep anoxic hypersaline basins Bannock and L’Atalante were sampled in intervals of 10 cm with increasing salinity. 15N isotope pairing incubation experiments showed the production of 29N2 and 30N2 gases in the chemoclines, ranging from 6.0 to 9.2 % salinity of the L’Atalante basin. Potential anammox rates ranged from 2.52 to 49.65 nmol N2 L?1 day?1 while denitrification was a major N2 production pathway, accounting for more than 85.5 % of total N2 production. Anammox-related 16S rRNA genes were detected along the L’Atalante and Bannock haloclines up to 24 % salinity, and the amplification of the hydrazine synthase genes (hzsA) further confirmed the presence of anammox bacteria in Bannock. Fluorescence in situ hybridisation and sequence analysis of 16S rRNA genes identified representatives of the marine anammox genus ‘Candidatus Scalindua’ and putatively new operational taxonomic units closely affiliated to sequences retrieved in marine environments that have documented anammox activity. ‘Scalindua brodae’ like sequences constituted up to 84.4 % of the sequences retrieved from Bannock. The anammox community in L’Atalante was different than in Bannock and was stratified according to salinity increase. This study putatively extends anammox bacterial habitats to extremely saline sulphidic ecosystems. 相似文献
103.
Mobility is an important factor influencing the range and persistence of local populations. However, mobility is very difficult to measure empirically and thus is poorly known in most taxa. Since ecological characteristics have been suggested as good estimators of mobility, we here explore the association between ecological characteristics and mobility. We surveyed night-active moths on a Swedish island, situated 16 km from the mainland, and compared ecological characteristics of the non-resident moths found on the island with those of a species pool of assumed potential vagrants from the neighbouring mainland. Species associated with high mobility were characterised by a large range, a high population density, an activity period during warm temperatures and by being habitat generalists or preferring open habitats. The generally assumed view of poly- and oligophagous species being more mobile than monophagous species was obscured by the effect of population density. Poly- and oligophagous species had higher population densities than did monophagous species, which probably explain their higher mobility found in this study. Our result highlights the need to consider the influence of ecological characteristics on mobility. This in turn will have implications for an increased understanding of distribution patterns, population persistence and how to prioritise conservation actions, especially since habitats and climate are under dramatic changes. In taxa where data on mobility are poor, ecological characteristics can be used as a proxy for mobility. 相似文献
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105.
Tracie Pennimpede Stefanie Wolter Lars Wittler Anne‐Karoline Ebert Wolfgang Rösch Raimund Stein Enrika Bartels Dominik Schmidt Thomas M. Boemers Eberhard Schmiedeke Per Hoffmann Susanne Moebus Bernhard G. Herrmann Markus M. Nöthen Heiko Reutter Michael Ludwig 《Birth defects research. Part A, Clinical and molecular teratology》2013,97(3):133-139
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107.
Julia D. I. Meuwese Anouk M. van Loon H. Steven Scholte Philipp B. Lirk Nienke C. C. Vulink Markus W. Hollmann Victor A. F. Lamme 《PloS one》2013,8(11)
Recurrent interactions between neurons in the visual cortex are crucial for the integration of image elements into coherent objects, such as in figure-ground segregation of textured images. Blocking N-methyl-D-aspartate (NMDA) receptors in monkeys can abolish neural signals related to figure-ground segregation and feature integration. However, it is unknown whether this also affects perceptual integration itself. Therefore, we tested whether ketamine, a non-competitive NMDA receptor antagonist, reduces feature integration in humans. We administered a subanesthetic dose of ketamine to healthy subjects who performed a texture discrimination task in a placebo-controlled double blind within-subject design. We found that ketamine significantly impaired performance on the texture discrimination task compared to the placebo condition, while performance on a control fixation task was much less impaired. This effect is not merely due to task difficulty or a difference in sedation levels. We are the first to show a behavioral effect on feature integration by manipulating the NMDA receptor in humans. 相似文献
108.
Assessing diversity is among the major tasks in ecology and conservation science. In ecological and conservation studies, epiphytic cryptogams are usually sampled up to accessible heights in forests. Thus, their diversity, especially of canopy specialists, likely is underestimated. If the proportion of those species differs among forest types, plot-based diversity assessments are biased and may result in misleading conservation recommendations. We sampled bryophytes and lichens in 30 forest plots of 20 m × 20 m in three German regions, considering all substrates, and including epiphytic litter fall. First, the sampling of epiphytic species was restricted to the lower 2 m of trees and shrubs. Then, on one representative tree per plot, we additionally recorded epiphytic species in the crown, using tree climbing techniques. Per tree, on average 54% of lichen and 20% of bryophyte species were overlooked if the crown was not been included. After sampling all substrates per plot, including the bark of all shrubs and trees, still 38% of the lichen and 4% of the bryophyte species were overlooked if the tree crown of the sampled tree was not included. The number of overlooked lichen species varied strongly among regions. Furthermore, the number of overlooked bryophyte and lichen species per plot was higher in European beech than in coniferous stands and increased with increasing diameter at breast height of the sampled tree. Thus, our results indicate a bias of comparative studies which might have led to misleading conservation recommendations of plot-based diversity assessments. 相似文献
109.
Daniela I. Schneider Markus Riegler Wolfgang Arthofer Hervé Mer?ot Christian Stauffer Wolfgang J. Miller 《PloS one》2013,8(12)
The common endosymbiotic Wolbachia bacteria influence arthropod hosts in multiple ways. They are mostly recognized for their manipulations of host reproduction, yet, more recent studies demonstrate that Wolbachia also impact host behavior, metabolic pathways and immunity. Besides their biological and evolutionary roles, Wolbachia are new potential biological control agents for pest and vector management. Importantly, Wolbachia-based control strategies require controlled symbiont transfer between host species and predictable outcomes of novel Wolbachia-host associations. Theoretically, this artificial horizontal transfer could inflict genetic changes within transferred Wolbachia populations. This could be facilitated through de novo mutations in the novel recipient host or changes of haplotype frequencies of polymorphic Wolbachia populations when transferred from donor to recipient hosts. Here we show that Wolbachia resident in the European cherry fruit fly, Rhagoletis cerasi, exhibit ancestral and cryptic sequence polymorphism in three symbiont genes, which are exposed upon microinjection into the new hosts Drosophila simulans and Ceratitis capitata. Our analyses of Wolbachia in microinjected D. simulans over 150 generations after microinjection uncovered infections with multiple Wolbachia strains in trans-infected lines that had previously been typed as single infections. This confirms the persistence of low-titer Wolbachia strains in microinjection experiments that had previously escaped standard detection techniques. Our study demonstrates that infections by multiple Wolbachia strains can shift in prevalence after artificial host transfer driven by either stochastic or selective processes. Trans-infection of Wolbachia can claim fitness costs in new hosts and we speculate that these costs may have driven the shifts of Wolbachia strains that we saw in our model system. 相似文献
110.
Luciana Cadore Stefani Suzana Muller Iraci L. S. Torres Bruna Razzolini Joanna R. Rozisky Felipe Fregni Regina Markus Wolnei Caumo 《PloS one》2013,8(10)