Intercomparison of Multiple UV-LIF Spectrometers using the Aerosol Challenge Simulator

Measurements of primary biological aerosol particles (PBAPs) have been conducted worldwide using ultraviolet light-induced fluorescence (UV-LIF) spectrometers. However, how these instruments detect and respond to known biological and non-biological particles, and how they compare, remains uncertain due to limited laboratory intercomparisons. Using the Defence Science and Technology Laboratory, Aerosol Challenge Simulator (ACS), controlled concentrations of biological and non-biological aerosol particles, singly or as mixtures, were produced for testing and intercomparison of multiple versions of the Wideband Integrated Bioaerosol Spectrometer (WIBS) and Multiparameter Bioaerosol Spectrometer (MBS). Although the results suggest some challenges in discriminating biological particle types across different versions of the same UV-LIF instrument, a difference in fluorescence intensity between the non-biological and biological samples could be identified for most instruments. While lower concentrations of fluorescent particles were detected by the MBS, the MBS demonstrates the potential to discriminate between pollen and other biological particles. This study presents the first published technical summary and use of the ACS for instrument intercomparisons. Within this work a clear overview of the data pre-processing is also presented, and documentation of instrument version/model numbers is suggested to assess potential instrument variations between different versions of the same instrument. Further laboratory studies sampling different particle types are suggested before use in quantifying impact on ambient classification.Peer reviewe

Let Me Learn with My Peers Online!: Foreign Language Learning Through Reciprocal Peer Tutoring

Rayenne Dekhinet, Keith Topping, David Duran, and Silvia Blanch describe a pilot project on the use of Internet-assisted reciprocal peer tutoring in foreign-language learning. The eight-week project connected Spanish-speaking English-language learners at a primary school in Catalonia with English-speaking Spanish-language learners at a Scottish primary school. Children were matched in pairs and acted as language tutors in their own mother tongue to their peers. Each week, the children wrote or corrected a text, depending on their role for that week, and sent messages to their peers. During and after the intervention, data were collected in the form of observations, participant and teacher interviews, and analysis of student writing in the target languages. The results of this study show how Internet technology can be leveraged with reciprocal peer tutoring to enhance language learning. (Contains 8 exhibits and 1 figure.

Linking morphodynamic response with sediment mass balance on the Colorado River in Marble Canyon: Issues of scale, geomorphic setting, and sampling design

Measurements of morphologic change are often used to infer sediment mass balance. Such measurements may, however, result in gross errors when morphologic changes over short reaches are extrapolated to predict changes in sediment mass balance for long river segments. This issue is investigated by examination of morphologic change and sediment influx and efflux for a 100 km segment of the Colorado River in Grand Canyon, Arizona. For each of four monitoring intervals within a 7 year study period, the direction of sand-storage response within short morphologic monitoring reaches was consistent with the flux-based sand mass balance. Both budgeting methods indicate that sand storage was stable or increased during the 7 year period. Extrapolation of the morphologic measurements outside the monitoring reaches does not, however, provide a reasonable estimate of the magnitude of sand-storage change for the 100 km study area. Extrapolation results in large errors, because there is large local variation in site behavior driven by interactions between the flow and local bed topography. During the same flow regime and reach-average sediment supply, some locations accumulate sand while others evacuate sand. The interaction of local hydraulics with local channel geometry exerts more control on local morphodynamic response than sand supply over an encompassing river segment. Changes in the upstream supply of sand modify bed responses but typically do not completely offset the effect of local hydraulics. Thus, accurate sediment budgets for long river segments inferred from reach-scale morphologic measurements must incorporate the effect of local hydraulics in a sampling design or avoid extrapolation altogether

Consumption of foods by young children with diagnosed campylobacter infection - a pilot case-control study

Objective: To determine whether parentally reported habitual intake of specific foods differed between children with diagnosed Campylobacter jejuni infection and children of a comparison group without diagnosed infection. Design, setting and subjects: Information was collected from the parents or primary caregivers of South Australian children aged 1–5 years with diagnosed C. jejuni (cases, n = 172) and an age- and gender-matched group of uninfected children (controls, n = 173). Frequency of consumption of 106 food and drink items was determined for the preceding two months by food-frequency questionnaire. Four children in the control group had recorded diarrhoeal episodes during the assessment period and were excluded, so 169 responses were evaluated for this group. Information was gathered on possible confounders including socio-economic status. Response frequencies were classified into three levels of consumption (rarely, weekly or daily) and statistical comparison was made by frequency of consumption of foods versus the ‘rarely’ classification for cases and controls, respectively. Results: Frequency of consumption of most foods, including starchy foods and fruits and vegetables, did not differ between cases and controls. However, reported consumption of eight food items (block and processed cheese (slices and spread), salami/fritz (a form of processed sausage), chicken nuggets, pasteurised milk, fish (canned or fresh) and hot French fries) was significantly higher by controls. Conclusions: The hypothesis that reported consumption of starchy foods was lower by cases than by controls was not supported by the data. However, consumption of some processed and unprocessed foods was higher by controls. Some of these foods have established bactericidal actions in vitro that may indicate a possible mechanism for this apparent protection

Influence of a dam on fine-sediment storage in a canyon river

Glen Canyon Dam has caused a fundamental change in the distribution of fine sediment storage in the 99-km reach of the Colorado River in Marble Canyon, Grand Canyon National Park, Arizona. The two major storage sites for fine sediment (i.e., sand and finer material) in this canyon river are lateral recirculation eddies and the main-channel bed. We use a combination of methods, including direct measurement of sediment storage change, measurements of sediment flux, and comparison of the grain size of sediment found in different storage sites relative to the supply and that in transport, in order to evaluate the change in both the volume and location of sediment storage. The analysis shows that the bed of the main channel was an important storage environment for fine sediment in the predam era. In years of large seasonal accumulation, approximately 50% of the fine sediment supplied to the reach from upstream sources was stored on the main-channel bed. In contrast, sediment budgets constructed for two short-duration, high experimental releases from Glen Canyon Dam indicate that approximately 90% of the sediment discharge from the reach during each release was derived from eddy storage, rather than from sandy deposits on the main-channel bed. These results indicate that the majority of the fine sediment in Marble Canyon is now stored in eddies, even though they occupy a small percentage ( similar to 17%) of the total river area. Because of a 95% reduction in the supply of fine sediment to Marble Canyon, future high releases without significant input of tributary sediment will potentially erode sediment from long-term eddy storage, resulting in continued degradation in Marble Canyon

Type-Decomposition of a Pseudo-Effect Algebra

The theory of direct decomposition of a centrally orthocomplete effect algebra into direct summands of various types utilizes the notion of a type-determining (TD) set. A pseudo-effect algebra (PEA) is a (possibly) noncommutative version of an effect algebra. In this article we develop the basic theory of centrally orthocomplete PEAs, generalize the notion of a TD set to PEAs, and show that TD sets induce decompositions of centrally orthocomplete PEAs into direct summands.Comment: 18 page

Applying phylogenomics to understand the emergence of Shiga Toxin producing Escherichia coli O157:H7 strains causing severe human disease in the United Kingdom

Shiga Toxin producing Escherichia coli (STEC) O157:H7 is a recently emerged zoonotic pathogen with considerable morbidity. Since the serotype emerged in the 1980s, research has focussed on unravelling the evolutionary events from the E. coli O55:H7 ancestor to the contemporaneous globally dispersed strains. In this study the genomes of over 1000 isolates from human clinical cases and cattle, spanning the history of STEC O157:H7 in the United Kingdom were sequenced. Phylogenetic analysis reveals the ancestry, key acquisition events and global context of the strains. Dated phylogenies estimate the time to the most recent common ancestor of the current circulating global clone to 175 years ago, followed by rapid diversification. We show the acquisition of specific virulence determinates occurred relatively recently and coincides with its recent detection in the human population. Using clinical outcome data from 493 cases of STEC O157:H7 we assess the relative risk of severe disease including HUS from each of the defined clades in the population and show the dramatic effect Shiga toxin complement has on virulence. We describe two strain replacement events that have occurred in the cattle population in the UK over the last 30 years; one resulting in a highly virulent strain that has accounted for the majority of clinical cases in the UK over the last decade. This work highlights the need to understand the selection pressures maintaining Shiga-toxin encoding bacteriophages in the ruminant reservoir and the study affirms the requirement for close surveillance of this pathogen in both ruminant and human populations

Towards integration of environmental and health impact assessments for wild capture fishing and farmed fish with particular reference to public health and occupational health dimensions

The paper offers a review and commentary, with particular reference to the production of fish from wild capture fisheries and aquaculture, on neglected aspects of health impact assessments which are viewed by a range of international and national health bodies and development agencies as valuable and necessary project tools. Assessments sometimes include environmental health impact assessments but rarely include specific occupational health and safety impact assessments especially integrated into a wider public health assessment. This is in contrast to the extensive application of environmental impact assessments to fishing and the comparatively large body of research now generated on the public health effects of eating fish. The value of expanding and applying the broader assessments would be considerable because in 2004 the United Nations Food and Agriculture Organization reports there were 41,408,000 people in the total ‘fishing’ sector including 11,289,000 in aquaculture. The paper explores some of the complex interactions that occur with regard to fishing activities and proposes the wider adoption of health impact assessment tools in these neglected sectors through an integrated public health impact assessment tool

Aleurone flour increases red-cell folate and lowers plasma homocyst(e)ine substantially in man

Aleurone flour (ALF) is a rich source of natural folate (>500 μg/100 g wet weight). Our objective was to establish whether intake of ALF in man can significantly improve folate status and reduce plasma homocyst(e)ine. We performed a randomised, controlled intervention, of 16 weeks duration, in free-living healthy individuals (mean age 46–52 years). Participants were assigned to one of three groups: ALF, 175 g bread made with ALF and placebo tablet each day; PCS, 175 g bread made with pericarp seed coat (PCS) flour and placebo tablet each day (low-folate control); or FA, 175 g bread made with PCS flour and tablet containing 640 μg folic acid each day (high-folate control). The daily folate intake contributed by the bread and tablet was 233 μg in the PCS group, 615 μg in the ALF group and 819 μg in the FA group. The number of participants completing all phases of the PCS, ALF and FA interventions was twenty-five, twenty-five and eighteen, respectively. Plasma and red-cell folate increased significantly (P<0·0001) and plasma homocyst(e)ine decreased significantly (P<0·0001) in the ALF and FA groups only. Plasma folate and red-cell folate in the ALF group (mean, 95 % CI) increased from baseline values of 12·9 (9·9, 15·7) nmol/l and 509 (434, 584) nmol/l to 27·1 (22·5, 31·7) nmol/l and 768 (676, 860) nmol/l, respectively. Plasma homocyst(e)ine in the ALF group decreased from 9·1 (8·2, 10·0) μmol/l at baseline to 6·8 (6·2, 7·5) μmol/l after 16 weeks. In conclusion, moderate dietary intake of ALF can increase red-cell folate and decrease plasma homocyst(e)ine substantially.Michael Fenech, Manny Noakes, Peter Clifton and David Toppin