Towards a Transverse Feedback System and Damper for the SPS in the LHC Era

The SPS will serve as injector for the LHC, accelerating up to 4 x 10^13 protons per cycle from 26 GeV/c to 450 GeV/c. The transverse feedback system (damper) is essential for keeping the transverse emittance blowup within the limits fixed for the LHC injector chain. The fast filamentation requires rapid damping of any injection errors. Injection errors are the combined result of steering errors and ripples on the magnet power supplies in the transfer line as well as from the PS extraction kicker and the SPS injection kicker. Besides damping injection oscillations the damper will also provide transverse feedback to stabilise the beam against the resistive wall coupled bunch instability. The required bandwidth, kick strength and power bandwidth (rise time) were discussed during the 1996 Montreux "Workshop on High Brightness Beams for Large Hadron Colliders" in the working group on "Active Emittance Control". In the present report the requirements for the damper are summarised and the development of a system to meet these specifications, based on the existing hardware, is described

Transverse feeback systems in the LHC and its injector: projected performance and upgrade paths

Transverse feedback systems are essential to preserve the small transverse emittances throughout the injector chain and in LHC itself. The striving for higher brilliance beams will put increased demands on the transverse feedback systems in the future. Possible upgrades of the LHC damper will address the low noise performance that is essential for operation in coast, while for the injectors a new generation of sophisticated digital electronics will replace the analogue signal processing as it is still employed in the PS booster today. A particular challenge for the smaller accelerators is the large frequency swing not present in the LHC

Cross-sectional study of the occurrence of Campylobacter spp., Yersinia enterocolitica, Salmonella spp., Rotavirus and Cryptosporidium parvum in dairy farms with problems of diarrhoea in northern Baden-Württemberg

Deckblatt-Impressum Inhaltsverzeichnis Einleitung Literaturübersicht Eigene Untersuchungen Besprechung der Ergebnisse Zusammenfassung Summary Anhang Literaturverzeichnis Danksagung SelbständigkeitserklärungZur Einschätzung der epidemiologischen Situation von Campylobacter spp., Yersinia enterocolitica, Salmonella spp., Rotaviren und Kryptosporidium parvum in Milchviehbeständen mit Durchfallproblemen im nördlichen Baden-Württemberg wurden in einer Querschnittsstudie 425 Kälberkotproben und 401 Kuhkotproben in 30 Milchviehbetrieben entnommen und untersucht. Zum Zeitpunkt der Probenentnahme zeigte mindestens ein Kalb je Betrieb klinische Symptome einer Durchfallerkrankung. In jedem Betrieb wurden alle Kälber im Alter von 0 - 21 Wochen und deren Mütter in die Studie miteinbezogen. Zusätzlich wurden betriebsspezifische und einzeltierspezifische Daten erhoben und Umgebungsproben von den Kälberboxen und dem Tränkegeschirr entnommen. Die untersuchten bakteriellen Erreger wurden mittels Anzüchtung aus den Kot- und Umgebungsproben isoliert und anschließend biochemisch (C. spp., Y. enterocolitica) bzw. anhand der Objektträgeragglutinationsreaktion (Salmonellen) differenziert. Zusätzlich wurden aus den Kälberkotproben bovine Rotaviren und Kryptosporidium parvum mittels kommerzieller ELISA-Tests bestimmt. Kryptosporidium parvum wurde parallel außerdem mittels phasenkontrastmikroskopischer Untersuchung nachgewiesen. Folgende Prävalenzen wurden festgestellt: Erreger Prävalenz Campylobacter spp. 29,6 % C. jejuni subsp. jejuni 89,7 % C. jejuni subsp. doylei 7,1 % C. coli 3,2 % Y. enterocolitica 0,7 % Salmonella spp. 4,7 % bovine Rotaviren 7,5 % Kryptosporidium parvum 19,3 % Die Prävalenzen aus den Kuhkotproben betrugen für Campylobacters spp. 13,9 %, für Y. enterocolitica 4 % und für Salmonellen 1,2 %. Sowohl eine klinisch festgestellte Durchfallerkrankung als auch die Nachweishäufigkeit der untersuchten Erreger waren vom Lebensalter der Kälber abhängig. Diarrhoeerkrankungen traten in den ersten vier Lebenswochen der Kälber signifikant häufig auf. Zwischen dem Auftreten einer klinischen Diarrhoe und dem Nachweis von Erregern bestand, bis auf bovine Rotaviren, jedoch kein Zusammenhang. Der Großteil der Durchfälle trat mithin unabhängig von den hier untersuchten Erregern auf. Die Erreger C. spp. und Y. enterocolitica spielen im Rahmen des Kälberdurchfallkomplexes eine untergeordnete Rolle, da für beide Erreger kein Zusammenhang zwischen dem Lebensalter, in dem Durchfallerkrankungen bei Kälbern vermehrt auftreten, und einer gleichzeitig vorhandenen Durchfallerkrankung feststellbar war. Salmonellen werden vermehrt von neugeborenen Kälbern (< 1 Woche) bzw. von Kälbern, die sich neben der Geburt in einer weiteren Stressphase befinden, ausgeschieden. Es bestand weiterhin kein signifikanter Zusammenhang zwischen der Ausscheidungshäufigkeit von C. parvum und einer Durchfallerkrankung. Kälber scheiden C. parvum nicht nur in den ersten vier Lebenswochen sondern auch später aus, was die Vermutung nahe legt, dass ältere Kälber als symptomlose Ausscheider fungieren. Somit verteilen sie den Erreger in der Umwelt und können Neugeborene damit infizieren. In der univariaten Analyse wirkten sich die Rinderzahl und Kälbergesamtzahl der einzelnen Betriebe, die Tränkemethode, die Haltung sowie die Rasse unterschiedlich signifikant auf die Nachweishäufigkeit der untersuchten Erreger aus. In Betrieben mit weniger als 132 Rindern waren Campylobacter spp. seltener nachweisbar als in Betrieben mit mehr als 144 Rindern. Salmonellen waren in Betrieben mit weniger als 22 Kälbern signifikant häufiger nachweisbar. Die Nachweishäufigkeit von Campylobacter war am größten bei abgesetzten bzw. in einer Gruppe gehaltenen Kälbern, während jene von C. parvum und bovinen Rotaviren bei einzeln gehaltenen bzw. mit dem Nuckeleimer getränkten Kälbern am größten war. Außerdem wurden bei schwarzbunten Kälbern signifikant seltener bovine Rotaviren nachgewiesen als bei Kälbern anderer Rassen. Die multivariate Analyse der hier vorliegenden Untersuchungen machte deutlich, dass sowohl bovine Rotaviren als auch Salmonellen häufige Erreger im Kälberdurchfallkomplex darstellen. In Bezug auf Campylobacter spp., Y. enterocolitica und C. parvum wurde deutlich, dass diese Erreger von meist symptomlosen, älteren Tieren ausgeschieden werden, und diese als Ansteckungsquelle für andere, meist jüngere Kälber dienen. Bei den fünf untersuchten Erregern handelt es sich um potentiell auch für den Menschen infektiöse Keime. Zudem stellen Kälber nach den in der hier vorliegenden Studie ermittelten Prävalenzwerten insgesamt ein Reservoir für diese fünf zoonotischen Erreger dar.In order to evaluate the epidemiological situation of Campylobacter spp., Yersinia enterocolitica, Salmonella spp., bovine Rotavirus and Cryptosporidium parvum in dairy farms of northern Baden-Württemberg, 425 fecal samples of calves and 401 fecal samples of cows from 30 dairy farms were collected and examined. At the time of sampling at least one calf of the farm showed clinical signs of diarrhea. In every farm all calves from birth till the age of 21 weeks and their mothers were included in the study. In addition, herd specific and individual animal data were collected as well as samples from the calfboxes and of the watery equipments. The bacterial agents were isolated by cultivation and differentiated biochemically (Campylobacter spp., Y. enterocolitica) or by slide-agglutination reaction (Salmonella spp.). In addition, bovine Rotavirus and C. parvum in fecal samples of calves were identified by use of commercial ELISA-kits. C. parvum further was also identified by phase-contrast microscopy. The following prevalences were determined: Pathogens Prevalence Campylobacter spp. 29,6 % C. jejuni subsp. jejuni 89,7 % C. jejuni subsp. doylei 7,1 % C. coli 3,2 % Y. enterocolitica 0,7 % Salmonella spp. 4,7 % bovine Rotavirus 7,5 % Cryptosporidium parvum 19,3 % In the fecal samples of the cows the prevalence of Campylobacter spp. was 13,9 %, of Y. enterocolitica 4 % and of Salmonella spp. 1,2 %. Both, clinical evident diarrhea and the frequencies of the examined causative agents were depended upon the age of the calves. Diarrhea appeared significantly more often during the first 4 weeks ante partum. A relationship between the appearance of diarrhea and prevalence of bovine Rotavirus was determined. Campylobacter spp .and Y. enterocolitica played a secondary role in the cause of calf diarrhea, as for both agents no relationship between the age at first viable clinical signs in the calves and the occurrence of diarrhea could be established. Salmonella spp. is frequently excreted by newborns calves (< 1 week) or older calves suffering from other stresses. No significant relationship between the frequency of excretion of C. parvum and clinical diarrhea could be determined. Calves excrete C. parvum during the first 4 weeks of life as well as later on, which leads to the conclusion, that older calves function as asymptomatic secretors. Therefore, older calves excreting C. parvum are very likely an important source of infection for newborn calves. The total number of cattle and calves in each herd, the method of watering and housing as well as the breed do exert significant influence on the detection frequency of the examined agents. In herds with less than 132 cattle, Campylobacter spp. was less frequently detected than in herds with more than 144 cattle. Salmonella spp. was significantly more often detected in farms with less than 22 calves. The detection frequency of Campylobacter spp. was highest in weaned or group-housed calves, whereas C. parvum and bovine Rotavirus were highest in single-housed calves or calves raised with nippelbucket. Furthermore, bovine Rotavirus was significantly less often detected in Holstein Friesian calves than in calves of other breeds. Multivariate analyses clearly demonstrated that bovine Rotavirus as well as Salmonella spp. play an important role in the cause of calf diarrhea. Concerning Campylobacter spp., Y. enterocolitica and C. parvum, it is suggested that they are mostly excreted by asymptomatic older calves which function as an important source of infection for younger ones. The 5 examined pathogenic agents are potentially infectious for humans. Further, because of the prevalences established in this study, calves appear to be a reservoir for these zoonotic agents, which is a factor in the process of human infection that should not to be underestimated

Phosphorylation regulates the assembly of chloroplast import machinery

Chloroplast function depends on the translocation of cytosolically synthesized precursor proteins into the organelle. The recognition and transfer of most precursor proteins across the outer membrane depend on a membrane inserted complex. Two receptor components of this complex, Toc34 and Toc159, are GTPases, which can be phosphorylated by kinases present in the hosting membrane. However, the physiological function of phosphorylation is not yet understood in detail. It is demonstrated that both receptors are phosphorylated within their G-domains. In vitro, the phosphorylation of Toc34 disrupts both homo- and heterodimerization of the G-domains as determined using a phospho-mimicking mutant. In endogenous membranes this mutation or phosphorylation of the wild-type receptor disturbs the association of Toc34, but not of Toc159 with the translocation pore. Therefore, phosphorylation serves as an inhibitor for the association of Toc34 with other components of the complex and phosphorylation can now be discussed as a mechanism to exchange different isoforms of Toc34 within this ensemble

Organic matter composition and dynamic in polygonal tundra soils

Arctic permafrost regions are postulated to be most strongly affected by the on-going global warming resulting in longer summer seasons and higher temperatures. This may cause the degradation of permafrost and increase the thickness of the annual superficial thawing layer (active layer) of permafrost soils. Thereby permafrost soils may turn from carbon sinks into carbon sources for the atmosphere as large, previously frozen carbon pools become available for microbial degradation, a key factor in the soil organic matter (OM) degradation. The aim of this thesis was to investigate soil organic matter of permafrost soil to identify stabilization mechanisms, soil bacterial communities and carbon pools preferably metabolised by soil bacteria using bulk, molecular lipid-biomarker, physical fractionation and radiocarbon analysis. In temperate soils stabilization mechanism of OM, mainly organo-mineral associations and soil aggregations, are well studied by separating the OM into functional pools with different turnover rates, which are determined by their chemical properties and bioavailability. However, little is known about the quality of the soil OM, its stability and its accessibility for the microbial community in permafrost soils. The most important location for microbial metabolic activity in permafrost soils is the active layer. Therefore, this thesis concentrated on investigating different soil horizons of the active layer and the still frozen permafrost top layer of the polygonal tundra in the Siberian Lena Delta, Russia. Soil samples were predominantly taken from Samoylov Island and for the characterisation of soil bacterial communities additional samples from Kurungnakh Island were also analysed. The results show that the OM of both different cryogenic structures (polygon rim and centre) on Samoylov Island is dominated by little-decomposed, higher plant-derived material as indicated by the dominance of long-chain lipid biomarkers (n-alkanes and n-fatty acids) and high C/N ratios (16-51). The bulk soil OM of the active layer of the water saturated polygon centre is very young (0 to 43 cm depth: modern to 300 yrs BP) indicating that plant roots introduce modern carbon into deeper soil horizons. In contrast, the 14C age of the bulk OM of the polygon rim increases strongly with depth in the active layer (0 to 32 cm depth: modern to 1950 yrs BP) and even further in the permafrost top layer (32-37 cm depth: 3050 yrs BP) suggesting a slow microbial OM degradation in this cold environment. Soil organic carbon in the polygon rim is mainly stored in the clay and fine silt sized fractions (< 6.3 μm). These fractions are surprisingly ‘young’ with 14C contents similar to the bulk soil values suggesting that organo-mineral associations are of little importance in the OM stabilization. Particular OM occluded in soil aggregates has increased carbon contents with depth and higher 14C ages (55-3080 yrs BP) than free light particular OM (modern-1240 yrs BP). This indicates that soil aggregation seems to be of a stabilization mechanism occurring only at greater soil depth. The living microbial soil biomass is dominated by Gram-positive and Gram-negative bacteria as indicated by the dominance of their phospholipid fatty acid biomarkers (PLFAs, membrane lipids of living microbial cells). Another bacterial biomarker are bacteriohopanepolyols (BHPs), which are almost exclusively produced by bacteria. In different soil horizons on Samoylov and Kurungnakh Island the soil horizons differed in the abundances of methanotrophs, cyanobacteria, soil-marker BHP-producing bacteria and unknown BHP-producing bacteria. The greatest structural diversity and highest BHP concentrations probably indicating a great bacterial diversity and biomass were observed in the uppermost organic soil horizons (Oi) of the polygon rim and centre. It seems that several soil properties as high organic carbon content and relatively low soil pH have a positive influence on the diversity of the BHP-producing bacterial community. Microorganisms seem to predominantly metabolise the youngest, presumably labile OM pools available, as the 14C ages of individual PLFA biomarkers were always lower than the 14C ages of the bulk OM from which the biomarkers were isolated. It can be further suggested that the microbial utilized labile OM pools are plant-derived as the microbial PLFA biomarkers have similar 14C ages the as long-chain (plant-derived) lipid biomarkers and the free particular organic matter (fPOM). The increasing 14C age of microbial PLFAs with soil depths suggested that microorganisms metabolise older carbon sources in greater soil depth. However, these sources are most likely still the most labile and plantderived OM pools available as fPOM has similar 14C ages as the PLFAs. Therefore, it is possible either that ‘old’, presumably more stable carbon pools are not in favour to microbial decomposition or are not bioavailable or are degraded by microorganism other than (aerobic) soil bacteria