Deposits and Cutoff Ages of Horseshoe and Marion Oxbow Lakes, Red River, Manitoba

Horseshoe Lake and the Marion Lake scar, along the Red River, southern Manitoba, were cored to investigate the timing of the meander cutoffs and the sedimentology of the channel in-fill deposits. The Horseshoe Lake core, 10.75 m long, consists of 9.73 m of silt-rich deposits inferred to be lacustrine from 0 to 4 m deep, transitional from 4 to 5 m deep and alluvial below 5 m deep. Four wood and charcoal specimens sampled from the core yielded radiocarbon ages of 310 ± 40, 1730 ± 50, 2040 ± 50 and 2240 ± 50 BP. The Marion Lake core, 16.77 m long, consists of 14.73 m of silt-rich deposits inferred to be lacustrine from 0 to 5 m deep and alluvial below 8.5 m deep; the transition is indistinct and falls between 5 to 8.5 m deep. Four wood samples from the fluvial deposits yielded radiocarbon ages of 1600 ± 40, 1700 ± 40, 1660 ± 40 and 1620 ± 40 BP. The cutoffs that led to the formation of Horseshoe and Marion lakes are interpreted to have occurred at ~1990 and ~1520 cal BP or shortly thereafter, respectively. The silt-rich, alluvial-lacustrine deposits in the lakes lack structural and textural characteristics that can be readily recognized in core to distinguish the depositional environments. The absence of coarse sediments at the base of the fluvial units at both sites implies that minor to negligible amounts of sand were transported along the thalwegs of the channels prior to the meanders being cutoff. The dominance of silt within the oxbow deposits reflects sediment supply as the geomorphic setting of the river is within an extensive glaciolacustrine clay plain.Le lac Horseshoe et l'ancien lac Marion ont fait l'objet de carottages dans le but d'établir le moment du recoupement de leur méandre et la sédimentologie des dépôts accumulés dans leur chenal. La carotte du lac Horseshoe (10,75 m) est constituée de 9,73 m de dépôts riches en limon, probablement lacustres entre 0 et 4 m de profondeur, de transition entre 4 et 5 m et alluviaux sous les 5 m. Quatre échantillons de bois et de charbon ont donné des âges au radiocarbone de 310 ± 40, 1730 ± 50, 2040 ± 50 et 2240 ± 50 BP. La carotte du lac Marion (16,77 m) est constituée de 14,73 m de dépôts riches en limon, apparemment lacustres entre 0 et 5 m et alluviaux sous les 8,5 m ; la transition, mal définie, se situe entre 5 et 8,5 m de profondeur. Quatre échantillons de bois provenant des dépôts fluviatiles ont donné des âges au radiocarbone de 1600 ± 40, 1700 ± 40, 1660 ± 40 et 1620 ± 40 BP. On estime que les recoupements qui ont donné naissance aux deux lacs se sont produits il y a environ 1990 (Horseshoe) et 1520 cal. BP (Marion), ou peu après. Les dépôts alluvio-lacustres riches en limon des lacs ne comportent pas de structures et de textures assez nettes pour permettre d’identifier leur milieux de sédimentation. L'absence, dans les deux cas, de sédiments grossiers à la base de l'unité fluviatile laisse supposer que des quantités minimes, voire négligeables, de sable ont été transportées le long des thalwegs avant que les recoupements ne surviennent. La prédominance du limon dans les dépôts des lacs en croissant reflète la provenance des sédiments, le cadre géomorphologique de la rivière étant celui d’une vaste plaine d'argile glaciolacustre.Los sedimentos de los lagos Horseshoe y Marion situados a lo largo del río Red al sur de Manitoba fueron estudiados para establecer la fecha de formación de meandros y la sedimentología de los depósitos de los canales. El núcleo testigo de sondeo proveniente del lago Horseshoe, de 10,75 m de largo, está compuestos de depósitos ricos en limo de hasta 9,73 m. Dichos depósitos son considerados como de origen lacustre en una región de 0 a 4 m de profundidad, de tipo de transición entre 4 y 5 m de profundidad y de origen aluvial por debajo de 5 m de profundidad. Cuatro especímenes de madera y de carbón obtenidos de dicho núcleo testigo fueron datados con radiocarbono proporcionando un edad cercana a los 310 ± 40, 1730 ± 50, 2040 ± 50 y 2240 ± 50 años BP. El núcleo testigo de sondeo de 16,77 m de largo proveniente del lago Marion, esta compuesto de una zona que abarca 14.73 m de depósitos arcillosos de origen lacustre entre 0-5 m de profundidad y de origen aluvial por debajo de los 8.5 m de profundidad; la zona de transición se sitúa entre 5 y 8.5 m de profundidad pero no se encuentra bien definida. La datación con radiocarbono de cuatro muestras de depósitos fluviales proporciono una edad que las sitúa hace unos 1600 ± 40, 1660 ± 40 y 1620 ± 40 años BP. Se cree que el corte de terreno que dio origen a la formación de los lagos Horseshoe y Marion ocurrió hace unos 19 900 a 15 200 años o poco tiempo después, respectivamente. Los depósitos ricos en limo de origen lacustre-aluvial de los lagos carecen de las características estructurales y de textura que pueden ser reconocidos fácilmente en el núcleo testigo para distinguir los ambientes de depósito. La ausencia de sedimentos de tipo grueso en la base de la unidad fluvial en ambos sitios indica que un aporte pequeño o insignificante de arena fue transportado a lo largo de la vaguada de los canales antes de que ocurriera la formación de los meandros. La predominancia de limos entre los depósitos del brazo muerto refleja el origen de los sedimentos y concuerda con el cuadro geomorfológico de un rió situado dentro de una planicie arcillosa glaciolacustre muy extensa

Development of a New in vitro System for Cystic Fibrosis Research

poster abstractIndividuals with cystic fibrosis (CF) have a life expectancy of 40 years and require daily treatments to mitigate the effects of the disease. CF impacts organs throughout the body, especially the lungs, where thick mucus builds up, impairs breathing, and provides an environment for bacterial growth. Chronic lung infection is the leading cause of mortality in CF. The majority of CF lung infections are caused by Pseudomonas aeruginosa, a common bacterium which typically does not cause disease in healthy individuals. In the CF lung, however, P. aeruginosa burrows into the thick mucus layer, evades the immune system, and resists antibiotic therapy by encasing itself in a protective matrix called a biofilm. Laboratory methods for studying biofilm are not true replicas of the CF lung environment, leaving a knowledge gap between how bacteria grow in a test tube (in vitro) and how they grow in the lungs of a person with CF. The focus of this work is to develop an improved laboratory model which combines artificial sputum (as a surrogate for mucus in the CF lung) and cultured CF airway epithelial cells. To assess the potential of this model, we have performed experiments to compare P. aeruginosa in artificial sputum versus standard laboratory media. Results demonstrate that P. aeruginosa in artificial sputum exhibits differences in growth, biofilm formation, toxin production, cytotoxicity, and protein expression, compared to results in standard media. These data suggest that our model system can contribute new information to the understanding of CF airway infection. The aim of future studies is to use this system to identify sputum components and bacterial proteins which have not been recognized previously by standard methods. It is our ultimate goal to contribute knowledge leading to improved longevity and quality of life for people with CF

Associations between diurnal preference, sleep quality and externalizing behaviours: a behavioural genetic analysis

Background - Certain aspects of sleep co-occur with externalizing behaviours in youth, yet little is known about these associations in adults. The present study: (1) examines the associations between diurnal preference (morningness versus eveningness), sleep quality and externalizing behaviours; (2) explores the extent to which genetic and environmental influences are shared between or are unique to these phenotypes; (3) examines the extent to which genetic and environmental influences account for these associations. Method - Questionnaires assessing diurnal preference, sleep quality and externalizing behaviours were completed by 1556 young adult twins and siblings. Results - A preference for eveningness and poor sleep quality were associated with greater externalizing symptoms [r=0.28 (95% CI 0.23–0.33) and 0.34 (95% CI 0.28–0.39), respectively]. A total of 18% of the genetic influences on externalizing behaviours were shared with diurnal preference and sleep quality and an additional 14% were shared with sleep quality alone. Non-shared environmental influences common to the phenotypes were small (2%). The association between diurnal preference and externalizing behaviours was mostly explained by genetic influences [additive genetic influence (A)=80% (95% CI 0.56–1.01)], as was the association between sleep quality and externalizing behaviours [A=81% (95% CI 0.62–0.99)]. Non-shared environmental (E) influences accounted for the remaining variance for both associations [E=20% (95% CI −0.01 to 0.44) and 19% (95% CI 0.01–0.38), respectively]. Conclusions - A preference for eveningness and poor sleep quality are moderately associated with externalizing behaviours in young adults. There is a moderate amount of shared genetic influences between the phenotypes and genetic influences account for a large proportion of the association between sleep and externalizing behaviours. Further research could focus on identifying specific genetic polymorphisms common to both sleep and externalizing behaviours

Comparison of heterotrophic bioleaching and ammonium sulfate ion exchange leaching of Rare Earth Elements from a Madagascan Ion-Adsorption Clay

Rare earth elements (REE) are considered to be a critical resource, because of their importance in green energy applications and the overdependence on Chinese imports. REE rich ion-adsorption deposits (IAD) result from tropical weathering of REE enriched igneous rocks. Commercial REE leaching from IAD, using salt solutions occurs via an ion-exchange mechanism. Bioleaching of IAD by Aspergillus or Bacillus, was compared to Uninoculated Control and Salt leaching (0.5 M ammonium sulfate) over 60 days. Salt leaching was most effective, followed by Aspergillus, Bacillus then Uninoculated Control. Most of the REE and major elements released by Salt leaching occurred before day 3. With bioleaching, REE and major elements release increased with time and had a greater heavy to light REE ratio. Similar total heavy REE release was observed in Salt leaching and Aspergillus (73.1% and 70.7% Lu respectively). In bioleaching experiments, pH was inversely correlated with REE release (R2 = 0.947 for Lu) indicating leaching by microbially produced acids. These experiments show the potential for bioleaching of REE from IAD, but dissolution of undesirable elements could cause problems in downstream processing. Further understanding of the bioleaching mechanisms could lead to optimization of REE recover

DOES LOW MAGNESIUM IN CYSTIC FIBROSIS CONTRIBUTE TO BACTERIAL PATHOGENICITY?

poster abstractCystic fibrosis (CF) is a genetic disease for which there is currently no cure. Individuals with CF are plagued by myriad symptoms, including chronic pneumonia, which diminishes quality of life and reduces life expectancy to 40 years. The most common bacterium in CF patients’ lungs is Pseudomonas aeruginosa, a highly adaptable organism capable of surviving robust antibi-otic treatment. At the heart of developing improved treatments for CF pa-tients is the need to better understand P. aeruginosa pathogenicity. To this end, we have been studying the role of magnesium, which is often found at below normal levels in CF patients. Magnesium is an essential element in numerous cellular functions in both bacteria and humans. In previous re-search, we developed a P. aeruginosa strain with a deletion of the magnesi-um transport protein MgtE, as well as 16 plasmids carrying different muta-tions of the mgtE gene. Experiments with these constructs demonstrated a relationship between magnesium transport and bacterial toxin production. In the research presented here, we hypothesize that lower levels of magnesium may trigger a bacterial response, causing a change in P. aeruginosa patho-genicity. Changes may include differential growth, toxin release, and for-mation of biofilms, which are surface-adhered, antibiotic tolerant bacterial communities in a protective polysaccharide matrix. Using various magnesi-um levels, we have measured P. aeruginosa growth rates, motility, biofilm formation, and cytotoxicity toward cultured cells derived from the CF bron-chial epithelium. Preliminary results suggest that lower magnesium contrib-utes to changes in the bacterium that favor persistence in the CF lung. On-going studies include the effect of long-term growth of P. aeruginosa in low magnesium and how this impacts a number of virulence factors. We antici-pate that our research will elucidate the relationship between magnesium and P. aeruginosa pathogenicity and potentially lead to improved treatments for CF patients

Locating the LCROSS Impact Craters

The Lunar CRater Observations and Sensing Satellite (LCROSS) mission impacted a spent Centaur rocket stage into a permanently shadowed region near the lunar south pole. The Sheperding Spacecraft (SSC) separated \sim9 hours before impact and performed a small braking maneuver in order to observe the Centaur impact plume, looking for evidence of water and other volatiles, before impacting itself. This paper describes the registration of imagery of the LCROSS impact region from the mid- and near-infrared cameras onboard the SSC, as well as from the Goldstone radar. We compare the Centaur impact features, positively identified in the first two, and with a consistent feature in the third, which are interpreted as a 20 m diameter crater surrounded by a 160 m diameter ejecta region. The images are registered to Lunar Reconnaisance Orbiter (LRO) topographical data which allows determination of the impact location. This location is compared with the impact location derived from ground-based tracking and propagation of the spacecraft's trajectory and with locations derived from two hybrid imagery/trajectory methods. The four methods give a weighted average Centaur impact location of -84.6796\circ, -48.7093\circ, with a 1{\sigma} un- certainty of 115 m along latitude, and 44 m along longitude, just 146 m from the target impact site. Meanwhile, the trajectory-derived SSC impact location is -84.719\circ, -49.61\circ, with a 1{\sigma} uncertainty of 3 m along the Earth vector and 75 m orthogonal to that, 766 m from the target location and 2.803 km south-west of the Centaur impact. We also detail the Centaur impact angle and SSC instrument pointing errors. Six high-level LCROSS mission requirements are shown to be met by wide margins. We hope that these results facilitate further analyses of the LCROSS experiment data and follow-up observations of the impact region.Comment: Accepted for publication in Space Science Review. 24 pages, 9 figure

Aspirin Use in Children for Fever or Viral Syndromes

Aspirin should not be used to treat acute febrile viral illness in children. (Strength of Recommendation [SOR]: C, based on case- control studies). Although no causal link has been proven, data from case-control and historic cohort studies demonstrate an association between aspirin use and Reye syndrome