Free Lamplighter Groups and a Question of Atiyah

We compute the von Neumann dimensions of the kernels of adjacency operators on free lamplighter groups and show that they are irrational, thus providing an elementary constructive answer to a question of Atiyah.Comment: AMSLaTeX, 10 pages, to appear in Amer J Mat

Virtual Integration Platforms (VIP) –A Concept for Integrated and Interdisciplinary Air Transportation Research and Assessment

The paper descibes a new methodology for a holistic development of air transportation concepts. The Virtual Integration Plattform (VIP) concept is based on an IT tool chain as well as human collaborative methods to deal with complex systems. As a result the definitions of future air transportation concepts for short range "Quiet and Clean", long range "Comfortable and Clean" and individual transport "Fast and Flexible" are presente

16S rRNA gene based analysis of Enterobacter sakazakii strains from different sources and development of a PCR assay for identification

BACKGROUND: E. sakazakii is considered to be an opportunistic pathogen, implicated in food borne diseases causing meningitis or enteritis especially in neonates and infants. Cultural standard identification procedures for E. sakazakii include the observation of yellow pigmentation of colonies and a positive [Image: see text] glucosidase activity. Up to now, only one PCR system based on a single available 16S rRNA gene sequence has been published for E. sakazakii identification. However, in our hands a preliminary evaluation of this system to a number of target and non-target strains showed significant specificity problems of this system. In this study full-length 16S rRNA genes of thirteen E. sakazakii strains from food, environment and human origin as well as the type strain ATCC 51329 were sequenced. Based on this sequence data a new specific PCR system for E. sakazakii was developed and evaluated. RESULTS: By phylogenetic analysis of the new full-length 16S rRNA gene sequence data obtained we could show the presence of a second phylogenetic distinct lineage within the E. sakazakii species. The newly developed 16S rRNA gene targeting PCR system allows identification of E. sakazakii strains from both lineages. The assay's ability to correctly identify different E. sakazakii isolates as well as to differentiate E. sakazakii from other closely related Enterobacteriaceae species and other microorganisms was shown on 75 target and non-target strains. CONCLUSION: By this study we are presenting a specific and reliable PCR identification system, which is able to correctly identify E. sakazakii isolates from both phylogenetic distinct lines within the E. sakazakii species. The impact of this second newly described phylogenetic line within the E. sakazakii species in view of clinical and food safety aspects need further investigation

An evaluation of the geographic method for recognizing innovations in nature, using zoo orangutans

Innovation and social learning are the raw materials for traditions and culture. Of these two, innovation has received far less scrutiny, largely because of difficulties assessing the innovation status of behaviors. A recent attempt proposes recognition of innovations in natural populations based on assessment of the behavior's properties and its geographic and local prevalence. Here we examine the validity of this approach and the list of 43 potential innovations it generated for wild orangutans by extending the comparison to zoo orangutans. First, we created an inventory of the behavioral repertoire in the zoo population. Four of ten putative innovations recognized in the field and potentially present in captivity did not occur despite appropriate conditions, suggesting they are indeed innovations. Second, we experimentally produced relevant conditions to evaluate whether another five potential innovations could be elicited. Based on their continued absence or on their latencies relative to known behaviors, four of the potential innovations could be assessed as innovations and one as a modification. Because 53% of relevant innovations recognized in the field could be confirmed in this analysis, and another 27% assigned possible innovation status, we conclude that the geographic method for detecting innovation in the wild is valid. However, the experiments also yielded up to 13 additional innovations, suggesting that zoo orangutans are far more innovative than wild ones. We discuss the implications of this latter finding with regard to limiting factors for the expansion of cultural repertoires in wild orangutan

Resistance profiles and genetic diversity of Escherichia coli strains isolated from acute bovine mastitis

Between March 2011 and February 2012 83 E. coli strains were isolated from mastitis milk samples from 83 different animals (67 farms) and tested for their sensitivity to various antibiotics by means of disk diffusion method and genotyped by determination of the phylogenetic groups as well as by pulsed field gel electrophoresis (PFGE). The antibiotics were chosen on the basis of their licenses for intramammary application in Switzerland. As many as 16.9 % of the isolates were resistant to one or more antimicrobial agents. Amoxicillin-clavulanic acid, gentamicin and third generation cephalosporins proved effective against the majority of these strains. Nevertheless, one blaCTX-M-14 harbouring extended-spectrum-beta-lactamase producing strain was found. Genetic analysis grouped most of the strains (87 %) into phylogenetic groups A and B1. PFGE genotyping demonstrated that E. coli from cows with mastitis even from the same farm were genotypically very diverse. = Entre mars 2011 et février 2012, 83 souches d'E. coli issues de 83 vaches différentes provenant de 67 exploitations ont été collectées et testées quant à leur sensibilité vis-à-vis de divers antibiotiques. Ces antibiotiques ont été choisis sur la base de leurs autorisations pour l'application intra mammaire en Suisse et le test a été effectué par diffusion sur gel d'agar. En outre toutes les souches ont été typisées quant à leur appartenance aux groupes phylogénétiques. 16.9 % des souches présentaient une résistance à un ou plusieurs antibiotiques. L'amoxicilline-acide clavulanique, la gentamicine et les céphalosporines de troisièmes générations se montraient efficaces contre la majorité des souches d'E. coli. On a toutefois trouvé une souche fabriquant un extended-spectrum-beta-lactamase qui portait le gène blaCTX-M-14. L'analyse génétique groupait la majorité des souches (87 %) dans les groupes phylogénétiques A et B1. La génotypisation par PFGE montrait une grande diversité entre les souches, même si elles provenaient de la même exploitation. = Zwischen März 2011 und Februar 2012 wurden 83 E. coli Stämme von 83 verschiedenen Kühen aus 67 Betrieben gesammelt und auf ihre Empfindlichkeit gegenüber verschiedenen Antibiotika getestet. Die Antibiotika wurden aufgrund der Zulassung für eine intramammäre Applikation in der Schweiz ausgesucht und die Empfindlichkeitstestung mittels Agardiffusions-Methode durchgeführt. Zudem wurden alle Stämme hinsichtlich ihrer Zugehörigkeit zu den phylogenetischen Gruppen wie auch mittels Pulsfeldgelelektrophorese (PFGE) genotypisiert. 16.9 % aller Stämme zeigten Resistenzen gegenüber einem oder mehreren Antibiotika. Amoxicillin-Clavulansäure, Gentamicin und Cephalosporine der dritten Generation erwiesen sind als wirksam gegen die Mehrheit der E. coli Stämme. Jedoch wurde ein extended-Spectrum-beta-Lactamase Bildner, welcher das blaCTX-M-14-Gen trägt, gefunden. Die genetische Analyse gruppierte das Gros der Stämme (87 %) in die phylogentischen Guppen A und B1. Die weitere Genotypisierung mittels PFGE zeigte eine grosse Diversität unter den E. coli Stämmen, auch wenn diese vom selben Betrieb stammten

Comparison of two chromogenic media and evaluation of two molecular based identification systems for Enterobacter sakazakii detection

BACKGROUND: Enterobacter sakazakii is a foodborne pathogen that has been associated with sporadic cases and outbreaks causing meningitis, necrotizing enterocolitis and sepsis especially in neonates. The current FDA detection method includes two enrichment steps, the subculturing of the second enrichment broth on a selective agar (VRBG), a further subculturing of selected grown colonies on TSA and the subsequent biochemical identification of yellow-pigmented colonies by API20E. However, there is a strong need for simplified methods for isolation and identification of E. sakazakii. In this study, two chromogenic media, which allow to indicate presumptive E. sakazakii colonies by the alpha glucosidase activity, as well as a newly developed 1,6-alpha-glucosidase based conventional PCR assay and a rRNA oligonucleotide probe based commercial test system for identification of presumptive E. sakazakii were evaluated on 98 target and non-target strains. The methods were compared with respect to specificity aspects. RESULTS: A total of 75 presumptive E. sakazakii and 23 non-target strains were analysed by using chromogenic media, alpha-glucosidase based PCR assay, and the VIT assay. For most presumptive E. sakazakii strains on the chromogenic media, the PCR and VIT assay confirmed the identification. However, for a number of presumptive E. sakazakii isolates from fruit powder, the alpha-glucosidase PCR and VIT assay did not correspond to the typical E. sakazakii colonies on DFI and ESIA. Further characterization by API32E identification, phylogenetic analysis of partial 16S rRNA sequences and ribotyping strongly suggested, that these strains did not belong to the species E. sakazakii. The newly developed alpha-glucosidase based PCR assay as well as the commercially available VIT Enterobacter sakazakii identification test showed an excellent correlation with the 16S rRNA data, and are thus well suited for identification of E. sakazakii. CONCLUSION: The results indicate that presumptive colonies on ESIA and DFI media need further species identification. Both evaluated molecular methods, the alpha-glucosidase PCR and the 16S RNA in situ hybridisation test (VIT), although based on completely different target regions and methodologies performed equally well in terms of specificity

Wide Band Propagation in Train-to-Train Scenarios - Measurement Campaign and First Results

Within the next decades the railway systems will change to fully autonomous high speed trains (HSTs). An increase in efficiency and safety and a reduction of costs would go hand in hand. Today’s centralized railway management system and established regulations can not cope with trains driving within the absolute braking distance as it would be necessary for electronic coupling or platooning maneuvers. Hence, to ensure safety and reliability, new applications and changes in the train control and management are necessary. Such changes demand new reliable control communication links between train-to-train (T2T) and future developments on train-to-ground (T2G). T2G will be covered by long term evolution-railway (LTE-R) which shall replace today’s global system for mobile communications-railway (GSM-R). The decentralized T2T communication is hardly investigated and no technology has been selected. This publication focuses on the wide band propagation for T2T scenarios and describes a extensive channel sounding measurement campaign with two HSTs. First results of T2T communication at high speed conditions in different environments are presented

Cloning and characterization of Enterobacter sakazakii pigment genes and in situ spectroscopic analysis of the pigment

Enterobacter sakazakii is considered an opportunistic foodborne pathogen that is characterized by formation of yellow-pigmented colonies. Because of the lack of basic knowledge about Enterobacter sakazakii genetics, the BAC approach and the heterologous expression of the pigment in Escherichia coli were used to elucidate the molecular structure of the genes responsible for pigment production in Enterobacter sakazakii strain ES5. Sequencing and annotation of a 33.025 bp fragment revealed seven ORFs that could be assigned to the carotenoid biosynthesis pathway. The gene cluster had the organization crtE-idi-XYIBZ, with the crtE-idi-XYIB genes putatively transcribed as an operon and the crtZ gene transcribed in the opposite orientation. The carotenogenic nature of the pigment of Enterobacter sakazakii wt was ascertained by in situ analysis using visible microspectroscopy and resonance Raman microspectroscop

Endophytic root colonization of gramineous plants by Herbaspirillum frisingense

Herbaspirillum frisingense is a diazotrophic betaproteobacterium isolated from C4-energy plants, for example Miscanthus sinensis. To demonstrate endophytic colonization unequivocally, immunological labeling techniques using monospecific polyclonal antibodies against two H. frisingense strains and green fluorescent protein (GFP)-fluorescence tagging were applied. The polyclonal antibodies enabled specific in situ identification and very detailed localization of H. frisingense isolates Mb11 and GSF30T within roots of Miscanthus×giganteus seedlings. Three days after inoculation, cells were found inside root cortex cells and after 7 days they were colonizing the vascular tissue in the central cylinder. GFP-tagged H. frisingense strains could be detected and localized in uncut root material by confocal laser scanning microscopy and were found as endophytes in cortex cells, intercellular spaces and the central cylinder of barley roots. Concerning the production of potential plant effector molecules, H. frisingense strain GSF30T tested positive for the production of indole-3-acetic acid, while Mb11 was shown to produce N-acylhomoserine lactones, and both strains were able to utilize 1-aminocyclopropane-1-carboxylate (ACC), providing an indication of the activity of an ACC-deaminase. These results clearly present H. frisingense as a true plant endophyte and, although initial greenhouse experiments did not lead to clear plant growth stimulation, demonstrate the potential of this species for beneficial effects on the growth of crop plant

CONTROLLING IM WISSENSMANAGEMENT – KONZEPTION EINES ALLGEMEINEN ANSATZES ZUR ERFOLGSBEWERTUNG IM WISSENSMANAGEMENT

Es ist allgemein akzeptiert, dass Wissensversorgung und interne Wissensweitergabe unverzichtbare Erfolgsfaktoren für Unternehmen im Wettbewerb sind. Offen ist allerdings wie man den diesbezüglichen Status eines Unternehmens messen oder diagnostizieren kann, um daraus konkrete und wirksame Maßnahmen für die Verbesserung des Wissensmanagements abzuleiten. Da es bisher keine methodisch zufrieden stellende Unterstützung dafür gibt, ist das Ziel des Beitrags eine Bestandsaufnahme und kritische Reflexion der bisherigen Ansätze zur Erfolgsmessung im Wissensmanagement sowie ein Beitrag für die Entwicklung einer konzeptionellen Grundlage