Prevalence and diversity of Campylobacter jejuni in pig herds on farms with and without cattle or poultry

The prevalence and diversity of Campylobacter jejuni was investigated in pig herds on farms with and without cattle or poultry production. A bacteriological screening of pig cecal samples from 247 finisher herds was carried out at the slaughter-house. Subsequently, a follow-up study was conducted in 24 herds (either with or without prior C. jejuni isolation from pigs) in which fecal samples were collected from pigs and, if present, cattle and poultry. Samples were analyzed for presence of Campylobacter, and subsequent analysis included species identification, serotyping, and, for selected strains, pulsed-field gel electrophoresis typing. In the slaughterhouse screening, C. jejuni was isolated from pigs in 21 (8.5%) herds, but no significant difference in prevalence was found between herd types (pigs, pigs and cattle, pigs and poultry). At the slaughterhouse, C. jejuni and Campylobacter coli prevalence in pigs was 2.3 and 90.1%, respectively. In the follow-up study, herd prevalence of C. jejuni was 8.3%, whereas C. jejuni and C. coli were isolated from 0.8 and 92.0% of pigs, respectively. In mixed production herds, C. jejuni predominated in cattle (42.7%) and poultry (31.6%), whereas C. jejuni was only isolated from 1.3 to 2.5% of pigs in these herds. There were no significant differences in C. jejuni or C. coli prevalence in pigs, cattle, and poultry between herds with and without prior C. jejuni isolation at the slaughterhouse. Pulsed-field gel electrophoresis typing did not yield evidence of C. jejuni transmission between cattle or poultry and pigs in mixed production herds. In contrast, pulsed-field gel electrophoresis analysis showed indistinguishable serotypes of C. coli in pigs and cattle in two herds. Verification of C. jejuni-positive pig samples showed that individual pigs can excrete high levels of C. jejuni and that mixed infection with C. jejuni and C. coli was common in C. jejuni-positive pigs. The results of our study suggest that transmission of C. jejuni between pigs and cattle or poultry in mixed production herds occurs infrequently. Detection of indistinguishable C. coli isolates in two herds, however, might indicate the existence of low-level transmission between pigs and cattle in herds of mixed production.     

Effect of psychrotrophic bacteria and of an isolated protease from Pseudomonas fluorescens M3/6 on the plasmin system of fresh milk

In the present study, we investigated the effect of Pseudomonas spp. growth on the plasmin enzymatic system in casein and whey fractions of fresh milk. Two bacterial strains, Pseudomonas spp. SRM28A and Pseudomonas fluorescens M3/6, were inoculated at a level of approximately 10(3) cfu/ml into fresh milk and incubated at 7 degrees C for 3 d. Bacterial counts were approximately 10(8) cfu/ml by d 3. Samples collected every 24 h were treated to separate the casein from the whey fraction. Casein and whey fractions were subjected to electrophoresis to visualize protein breakdown and plasmin activity and to colorimetric assays to quantify plasmin-related activities. With psychrotrophic bacterial growth, plasmin levels in casein fractions decreased significantly and in whey fractions increased then decreased significantly. Fresh milk results were similar for the two strains and were similar to earlier results with reconstituted nonfat dry milk. A transmission electron microscopy study by immunocytochemistry showed the presence of plasmin in casein micelles and its disappearance upon microbial growth in the milk. We hypothesized that extracellular microbial proteases produced by psychrotrophic microorganisms are responsible for this effect. To confirm this, an extracellular bacterial protease was isolated from Pseudomonas fluorescens M3/6 by ammonium sulfate fractionation and ion-exchange chromatography and incubated with fresh milk. Milk samples analyzed during incubation with the protease had significantly increased plasmin and plasminogen activities in the whey fraction within 5 h of incubation, while differences in activities in the casein fraction occurred at time 7.5 h for plasmin activity and 10 h of incubation for plasminogen activity. These quantitative data were supported by plasmin activity as visualized by casein-SDS-PAGE. These results suggest that growth of the Pseudomonas strains in fresh milk, and particularly their production of extracellular proteases, may be a causative factor in the release of plasmin from the casein micelle. Such plasmin release could affect the quality of cheeses and other food products that utilize dairy ingredients.     

Environmental air pollution and DNA adducts in Copenhagen bus drivers--effect of GSTM1 and NAT2 genotypes on adduct levels

Fecal samples from 335 dairy farm residents and 1458 cattle on 80 farms were tested for Vero cytotoxin (VT)-producing Escherichia coli (VTEC). Residents were also tested for antibodies to VT1 and O157 lipopolysaccharide (LPS). Residents and cattle on farms with VTEC-positive persons or E. coli O157:H7-positive cattle were retested. Twenty-one persons (6.3%) on 16 farms (20.8%) and 46% of cattle on 100% of the farms had VTEC in fecal samples. Human VTEC isolates included E. coli O157:H7 and 8 other serotypes, 4 of which were present in cattle on the same farms. More persons had antibodies to VT1 (41%) than to O157 LPS (12.5%). Seropositivity to O157 LPS was associated with isolation of E. coli O157:H7 on the farm (P = .022). Human VTEC infection was negatively associated with age (P < .05) and was not associated with clinical illness. Many dairy farm residents experience subclinical immunizing VTEC infections at a young age, which frequently involve non-O157 VTEC found in cattle.     

The effect of external flow on the feeding currents of sessile microorganisms

Microscopic sessile suspension feeders live attached to surfaces and, by consuming bacteria-sized prey and by being consumed, they form an important part of aquatic ecosystems. Their environmental impact is mediated by their feeding rate, which depends on a self-generated feeding current. The feeding rate has been hypothesized to be limited by recirculating eddies that cause the organisms to feed from water that is depleted of food particles. However, those results considered organisms in still water, while ambient flow is often present in their natural habitats. We show, using a point-force model, that even very slow ambient flow, with speed several orders of magnitude less than that of the self-generated feeding current, is sufficient to disrupt the eddies around perpendicular suspension feeders, providing a constant supply of food-rich water. However, the feeding rate decreases in external flow at a range of non-perpendicular orientations due to the formation of recirculation structures not seen in still water. We quantify the feeding flow and observe such recirculation experimentally for the suspension feeder Vorticella convallaria in external flows typical of streams and rivers.     

Frontier-based performance analysis models for supply chain management: State of the art and research directions

Effective supply chain management relies on information integration and implementation of best practice techniques across the chain. Supply chains are examples of complex multi-stage systems with temporal and causal interrelations, operating multi-input and multi-output production and services under utilization of fixed and variable resources. Acknowledging the lack of system’s view, the need to identify system-wide and individual effects as well as incorporating a coherent set of performance metrics, the recent literature reports on an increasing, but yet limited, number of applications of frontier analysis models (e.g. DEA) for the performance assessment of supply chains or networks. The relevant models in this respect are multi-stage models with various assumptions on the intermediate outputs and inputs, enabling the derivation of metrics for technical and cost efficiencies for the system as well as the autonomous links. This paper reviews the state of the art in network DEA modeling, in particular two-stage models, along with a critical review of the advanced applications that are reported in terms of the consistency of the underlying assumptions and the results derived. Consolidating current work in this range using the unified notations and comparison of the properties of the presented models, the paper is closed with recommendations for future research in terms of both theory and application.     

Surface wrinkling: the phenomenon causing bees in bitumen

The so called “bee phenomenon” in bitumen has been investigated by means of AFM quantitative nanomechanical property mapping. Bees are a phenomenon that can be observed by topography measurements using AFM. The characteristic “bee” appearance comes from regions with alternating higher and lower bands in the surface topography of bitumen, which are surrounded by a flat area. The proposed mechanism for bee formation is phase separation and differential contraction during cooling from melt temperatures leading to wrinkling due to differences in the elastic modulus of the material phases. Using a laminate wrinkling model, the thickness of the bee laminate was calculated from the wavelengths and Young’s moduli of the bee laminate and the matrix. It was found to vary between 70 and 140 nm for the five bitumen samples that contained significant amounts of wax.     

Carrot cropping on organic soil is a hotspot for nitrous oxide emissions

The emissions of the greenhouse gas nitrous oxide (N₂O) were measured from a non nitrogen fertilized carrot (Daucus carota ssp. sativa) field on an organic soil in Sweden during one cropping and post-harvest season. The cumulative emission during the measuring period of 149?days was 41 (±2.8) kg N₂O ha^?1. Dividing the measuring period into a cropping and a post-harvest period revealed that the presence of carrots strongly stimulated N₂O emissions, as the emission during the cropping period was one order of magnitude higher compared to the post-harvest period. The N₂O emission from the carrot field were higher than fluxes reported from cereal crop and grass production, but in the same order as reported fluxes from vegetable cropping on organic soils. In conclusion, our results indicate that the cultivation of root vegetable, such as carrots, on organic soil can be a high point source for N₂O emissions.     

Using enterprise architecture analysis and interview data to estimate service response time

Insights into service response time is important for service-oriented architectures and service management. However, directly measuring the service response time is not always feasible or can be very costly. This paper extends an analytical modeling method which uses enterprise architecture modeling to support the analysis. The extensions consist of (i) a formalization using the Hybrid Probabilistic Relational Model formalism, (ii) an implementation in an analysis tool for enterprise architecture and (iii) a data collection approach using expert assessments collected via interviews and questionnaires. The accuracy and cost effectiveness of the method was tested empirically by comparing it with direct performance measurements of five services of a geographical information system at a Swedish utility company. The tests indicate that the proposed method can be a viable option for rapid service response time estimates when a moderate accuracy within 15% is sufficient.     

From the times of the first scribes: innovation and technology within graphic design

The authors use their different work and training background as perspectives for discussing the changing world of graphical design. In this digital world, expert knowledge of the technology is essential, but the authors argue that a consequence of prioritising technical expertise in the new interdisciplinary IT- design studies may be a loss of quality in design. To improve the depth in design the authors introduce a psychological framework for design work and on this basis they suggest a systematic method. The method is a 4-step conceptual model: reason, function, emotion and senses, and technology. The model interacts with all phases of the design, and functions as a generating-creating and execution-evaluation system. The authors emphasise that evaluation is embedded throughout the design process. They suggest that a systematic method becomes the guiding tool in interdisciplinary design education, an essential part of the students design qualifications as well as an essential tool in design work.     

Investigation of the Equivalence of National Dew-Point Temperature Realizations in the ?50?°C to +?20?°C Range

In the field of humidity quantities, the first CIPM key comparison, CCT-K6 is at its end. The corresponding European regional key comparison, EUROMET.T-K6, was completed in early 2008, about 4?years after the starting initial measurements in the project. In total, 24 NMIs from different countries took part in the comparison. This number includes 22 EURAMET countries, and Russia and South Africa. The comparison covered the dew-point temperature range from ?50?°C to +20?°C. It was carried out in three parallel loops, each with two chilled mirror hygrometers as transfer standards in each loop. The comparison scheme was designed to ensure high quality results with evenly spread workload for the participants. It is shown that the standard uncertainty due to the long-term instability was smaller than 0.008?°C in all loops. The standard uncertainties due to links between the loops were found to be smaller than 0.025?°C at ?50?°C and 0.010?°C elsewhere. Conclusions on the equivalence of the dew-point temperature standards are drawn on the basis of calculated bilateral degrees of equivalence and deviations from the EURAMET comparison reference values (ERV). Taking into account 16 different primary dew-point realizations and 8 secondary realizations, the results demonstrate the equivalence of a large number of laboratories at an uncertainty level that is better than achieved in other multilateral comparisons so far in the humidity field.