80 research outputs found
Diffusione dei vibrioni nell'emisfero settentrionale associata al riscaldamento delle acque.
No full textDevelopment and application of monoclonal antibodies for in situ detection of indigenous bacterial strains in aquatic ecosystems
No full textLong-term effects of ocean warming on the prokaryotic community: evidence from the vibrios
No full textThe long-term effects of ocean warming on prokaryotic communities are unknown because of lack of historical data. We overcame this gap by applying a retrospective molecular analysis to the bacterial community on formalin-fixed samples from the historical Continuous Plankton Recorder archive, which is one of the longest and most geographically extensive collections of marine biological samples in the world. We showed that during the last half century, ubiquitous marine bacteria of the Vibrio genus, including Vibrio cholerae, increased in dominance within the plankton-associated bacterial community of the North Sea, where an unprecedented increase in bathing infections related to these bacteria was recently reported. Among environmental variables, increased sea surface temperature explained 45% of the variance in Vibrio data, supporting the view that ocean warming is favouring the spread of vibrios and may be the cause of the globally increasing trend in their associated diseases
Electron cloud observation in LHC
No full textOperation of LHC with bunch trains at different spacings
has revealed the formation of an electron cloud inside the
machine. The main observations of electron cloud build
up are the pressure rise measured at the vacuum gauges
in the warm regions, as well as the increase of the beam
screen temperature in the cold regions due to an additional
heat load. The effects of the electron cloud were also visible as instability and emittance growth affecting the last bunches of longer trains, which could be improved running with higher chromaticity or larger transverse emittances. A summary of the 2010 and 2011 observations and measurements and a comparison with models will be presented.
The efficiency of scrubbing to improve the machine running performance will be briefly discussed
Single and combined effects of sympathetic and parasympathetic activity on perceptual sensitivity and attention
No full textPulse rate and cephalic pulse volume were recorded from 17 male and 37 female normal subjects during performance of an attentional task under high and low stress conditions. Verbal threshold (perceptual sensitivity) and word recognition (attention) were assessed using a visual verbal recognition task. Subjects were divided at the median for pulse rate and pulse volume during baseline, instruction, and task periods and grouped in terms of these two measures to represent different patterns of parasympathetic (vagal) and sympathetic activity. Analysis of variance was used to examine the effects of gender, stress condition, and autonomic pattern on autonomic activity, perceptual sensitivity, and attentional performance. Gender showed significant effects for pulse rate with higher scores for women during the instruction and task periods. High stress reduced perceptual sensitivity and resulted in better attentional performance. Whereas stress-induced sympathetic activity was related to low perceptual sensitivity and good attentional performance, high sympathetic in conjunction with low vagal baseline activity predicted relatively high perceptual sensitivity and poor attentional performance. Low or high baseline activity in both autonomic systems predicted low perceptual sensitivity and good attentional performance. Predictions of perception and attention can be improved by examining the effects of patterns of sympathetic and parasympathetic activity
Lysogeny and virus‐induced mortality of bacterioplankton in surface, deep, and anoxic marine waters
No full textInternational audienceLysogeny (bacteria containing inducible prophages) and lytic viral infection (bacteria in a lytic stage of infection) were investigated at the community level in contrasting marine environments such as estuarine versus offshore waters, surface versus deep waters, and oxic versus anoxic waters in the Mediterranean and Baltic Seas. The frequency of lysogenic cells (FLC) in bacterioplankton communities ranged from not detectable to 84% as estimated by prophage induction due to mitomycin C, and highest values were typically found in deep waters (800-2,000 m). Transmission electron microscopy based estimates of virus-induced mortality of bacterioplankton (VMB) ranged from a few percent to 71%, and highest values were found in anoxic waters of the Baltic Sea. FLC and the frequency of infected cells (FIC) were related in form of a negative power function indicating that environments exist where one of the two viral life strategies prevails. Across all investigated environments, FLC was negatively related to bacterial abundance and production, whereas FIC showed a positive relationship with viral and bacterial parameters. FIC was higher and FLC was lower in moderately productive estuarine and offshore surface waters than in less productive mesopelagic and deep waters. Thus, lysogeny seems to be a survival strategy at low host abundance and activity, whereas high host abundance and activity seems to favor the lytic life cycle. The key process for the prevalence of lytic infection compared to prophage replication at high host abundance could be competition due to outnumbering. Between 11% and 88% (average, 35%) of the bacteria contained a functional (lytic or lysogenic) viral genome
ADT and OBSBOX in 2016
No full textA performant transverse feedback is vital for accelerators like LHC. The LHC transverse feedback (ADT) provides a lot of important data and functionality outside of the " damping envelope ". The contribution summarizes the ADT performance in 2016, and presents the newly implemented and commissioned features. Among those is the most awaited online instability detection system, but also new excitation modes allowing to perform precision beam measurements like the tune shift along the batch, excitation for automatic coupling correction or single jaw collimator impedance
Correlation of compressive stress with spalling of plasma sprayed ceramic materials
No full textCeramics on metal substrates for potential use as high temperature seals or other applications are exposed to forces originating from differences in thermal expansion between the ceramic and the metal substrate. This report develops a relationship between the difference in expansion of the ceramic and the substrate, defines conditions under which shear between the ceramic and the substrate occurs, and those under which bending forces are produced in the ceramic. The off-axis effect of compression forces resulting from high temperature plastic flow of the ceramic producing buckling of the ceramic is developed. Shear is associated with the edge or boundary stresses on the component while bending is associated with the distortion of an interior region. Both modes are significant in predicting life of the ceramic
A novel biosynthetic pathway providing precursors for fatty acid biosynthesis and secondary metabolite formation in myxobacteria
No full textShort chain carboxylic acids are well known as the precursors of fatty acid and polyketide biosynthesis. Iso-fatty acids, which are important for the control of membrane fluidity, are formed from branched chain starter units (isovaleryl-CoA and isobutyryl-CoA), which in turn are derived from the degradation of leucine and valine, respectively. Branched chain carboxylic acids are also employed as starter molecules for the biosynthesis of secondary metabolites, e.g. the therapeutically important anthelmintic agent avermectin or the electron transport inhibitor myxothiazol. During our studies on myxothiazol biosynthesis in the myxobacterium, Stigmatella aurantiaca, we detected a novel biosynthetic route to isovaleric acid. After cloning and inactivation of the branched chain keto acid dehydrogenase complex, which is responsible for the degradation of branched chain amino acids, the strain is still able to produce iso-fatty acids and myxothiazol. Incorporation studies employing deuterated leucine show that it can only serve as precursor in the wild type strain but not in the esg mutant. Feeding experiments using C-13-labeled precursors show that isovalerate is efficiently made from acetate, giving rise to a labeling pattern in myxothiazol that provides evidence for a novel branch of the mevalonate pathway involving the intermediate 3,3-dimethylacryloyl-CoA. 3,3-Dimethylacrylic acid was synthesized in deuterated form and fed to the esg mutant, resulting in strong incorporation into myxothiazol and iso-fatty acids. Similar experiments employing Myxococcus xanthus revealed that the discovered biosynthetic route described is present in other myxobacteria as well
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