Influences and drivers of woody debris movement in urban watercourses

Abstract It is recognised that the blockage of culverts by woody debris can result in an increased risk of infrastructure damage and flooding. To date, debris transport analysis has focused on regional fluvial systems and large woody debris, both in flume and field experiments. Given the social and economic risk associated with urban flooding, and as urban drainage design shifts away from subsurface piped network reliance, there is an increasing need to understand debris movement in urban watercourses. The prediction of urban watercourse small woody debris (SWD) movement, both quantity and risk, has undergone only limited analysis predominantly due to lack of field data. This paper describes the development of a methodology to enable the collection of accurate and meaningful SWD residency and transportation data from watercourses. The presented research examines the limitations and effective function of PIT tag technology to collect SWD transport data in the field appropriate for risk and prediction analysis. Passive integrated transponder (PIT) technology provides a method to collect debris transport data within the urban environment. In this study, the tags are installed within small woody debris and released at known locations into a small urban natural watercourse enabling monitoring of movement and travel time. SWD velocity and detention are collated with solute time of travel, watercourse and point flow characteristics to identify the relationships between these key variables. The work presented tests three hypotheses: firstly, that the potential for unobstructed or un-detained SWD movement increases with flow velocity and water level. Secondly, that SWD travel distance, and the resistance forces along this travel path, influence SWD transport potential. Thirdly, the relationship between SWD and channel dimensions is examined with the aim of advancing representative debris transport prediction modelling.</jats:p

Life Beneath Glacial Ice - Earth(!) Mars(?) Europa(?)

We are investigating a set of cold springs that deposit sulfur and carbonate minerals on the surface of a Canadian arctic glacier. The spring waters and mineral deposits contain microorganisms, as well as clear evidence that biological processes mediate subglacial chemistry, mineralogy, and isotope fractionation . The formation of native sulphur and associated deposits are related to bacterially mediated reduction and oxidation of sulphur below the glacier. A non-volcanic, topography driven geothermal system, harboring a microbiological community, operates in an extremely cold environment and discharges through solid ice. Microbial life can thus exist in isolated geothermal refuges despite long-term subfreezing surface conditions. Earth history includes several periods of essentially total glaciation. lee in the near subsurface of Mars may have discharged liquid water in the recent past Cracks in the ice crust of Europa have apparently allowed the release of water to the surface. Chemolithotrophic bacteria, such as those in the Canadian springs, could have survived beneath the ice of "Snowball Earth", and life forms with similar characteristics might exist beneath the ice of Mars or Europa. Discharges of water from such refuges may have brought to the surface living microbes, as well as longlasting chemical, mineralogical, and isotopic indications of subsurface life

Phase 1 study of sirolimus in combination with oral cyclophosphamide and topotecan in children and young adults with relapsed and refractory solid tumors.

PurposeTo determine the maximum tolerated dose (MTD), toxicities, and pharmacodynamics effects of sirolimus combined with oral metronomic topotecan and cyclophosphamide in a pediatric population.Materials and methodsPatients who were 1 to 30 years of age with relapsed/refractory solid tumors (including CNS) were eligible. Patients received daily oral sirolimus and cyclophosphamide (25-50 mg/m2/dose) on days 1-21 and oral topotecan (0.8 mg/m2/dose) on days 1-14 in 28-day cycles. Sirolimus steady-state plasma trough concentrations of 3-7.9 ng/mL and 8-12.0 ng/mL were evaluated, with dose escalation based on a 3+3 phase 1 design. Biomarkers of angiogenesis were also evaluated.ResultsTwenty-one patients were treated (median age 18 years; range 9-30). Dose-limiting toxicities included myelosuppression, ALT elevation, stomatitis, and hypertriglyceridemia. The MTD was sirolimus with trough goal of 8-12.0 ng/mL; cyclophosphamide 25 mg/m2/dose; and topotecan 0.8 mg/m2/dose. No objective responses were observed. Four patients had prolonged stable disease &gt; 4 cycles (range 4-12). Correlative biomarker analyses demonstrated reductions in thrombospondin-1 (p=0.043) and soluble vascular endothelial growth factor receptor-2 plasma concentrations at 21 days compared to baseline.ConclusionsThe combination of oral sirolimus, topotecan, and cyclophosphamide was well tolerated and biomarker studies demonstrated modulation of angiogenic pathways with this regimen

A novel analytical ultracentrifugation based approach to the low resolution structure of gum arabic

Under investigation are the structural properties of gum arabic, an industrially important biopolymer for use as a stabilizer or in drug delivery, using Analytical Ultracentrifugation—a well-established, matrix-free probe for macromolecular size and shape. These results are combined with chromatographically-coupled methods (multi-angle light scattering, differential press imbalance viscometry) to provide a global analysis of its structure in varying ionic strength conditions. This analysis indicates that gum Arabic may have a compact, elliptical structure in solution, the significance of which for biotechnological use is indicated. This modelling method can be applied to other biopolymers and synthetic polymers

The Effect of Selection for Desiccation Resistance on Cold Tolerance of Drosophila Melanogaster

Low Temperature and Desiccation Stress Are Thought to Be Mechanistically Similar in Insects, and Several Studies Indicate that There is a Degree of Cross-Tolerance between Them, such that Increased Cold Tolerance Results in Greater Desiccation Tolerance and Vice Versa. This Assertion is Tested at an Evolutionary Scale by Examining Basal Cold Tolerance, Rapid Cold-Hardening (RCH) and Chill Coma Recovery in Replicate Populations of Drosophila Melanogaster Selected for Desiccation Resistance (With Controls for Both Selection and Concomitant Starvation) for over 50 Generations. All of the Populations Display a RCH Response, and There is No Effect of Selection Regime on RCH or Basal Cold Tolerance, Although There Are Differences in Basal Cold Tolerance between Sampling Dates, Apparently Related to Inter-Individual Variation in Development Time. Flies Selected for Desiccation Tolerance Recover from Chill Coma Slightly, But Significantly, Faster Than Control and Starvation-Control Flies. These Findings Provide Little Support for Cross-Tolerance between Survival of Near-Lethal Cold and Desiccation Stress in D. Melanogaster. © 2007 the Authors