The effects of dietary selenomethionine on the escape behaviours of Fathead Minnows

Selenium is both an essential nutrient and a toxicant for animals, with only a relatively small concentration change separating the two. Toxicological work has reported various effects of selenium on fishes, including developmental impacts and deformities of the musculature and sensory systems. Behavioural ecotoxicology, a more sensitive study of toxicity, has also provided evidence that sublethal concentrations of selenium are having measurable impacts, such as negatively affecting swimming behaviours, in real-world ecosystems. In this thesis, I assessed the impacts of a selenomethionine-laden diet on the escape behaviours of the Fathead Minnow. Using kinematic analysis, I observed how fish responded to various looming threats. I exposed fish to sub-chronic periods of environmentally relevant concentrations of selenium in the form of selenomethionine-spiked diets. I achieved whole-body concentrations that approach Canadian tissue-specific guidelines for wild fish populations. In my first experiment, I used a weight drop to test the fish’s ability to respond to a mechanosenory stimulus and the performance of their fast-start response. My second experiment focused on the impacts of selenomethionine on visual acuity and how it affects visual perception of a threat. I also investigated how exposed fish would recover from any potential impacts when returned to a contaminant-free diet. My results indicated there was no significant effect of selenomethionine on either the visual response to a threat, or burst swimming behaviours of the fast-start response in Fathead Minnows. Additionally, there were no latent changes to Fathead Minnow escape behaviour throughout the recovery period. These results were contrary to both my predictions and the literature that showed critical swimming behaviour was compromised in selenomethionine -exposed freshwater fish. My work helps to show that the effects of toxicants on behaviours can be highly specific and cannot be generalized

The Local Environments of Core-Collapse SNe within Host Galaxies

We present constraints on core-collapse supernova progenitors through observations of their environments within host galaxies. This is achieved through 2 routes. Firstly, we investigate the spatial correlation of supernovae with host galaxy star formation using pixel statistics. We find that the main supernova types form a sequence of increasing association to star formation. The most logical interpretation is that this implies an increasing progenitor mass sequence going from the supernova type Ia arising from the lowest mass, through the type II, type Ib, and the supernova type Ic arising from the highest mass progenitors. We find the surprising result that the supernova type IIn show a lower association to star formation than type IIPs, implying lower mass progenitors. Secondly, we use host HII region spectroscopy to investigate differences in environment metallicity between different core-collapse types. We find that supernovae of types Ibc arise in slightly higher metallicity environments than type II events. However, this difference is not significant, implying that progenitor metallicity does not play a dominant role in deciding supernova type.Comment: to appear in Proceedings of IAU 279 "Death of Massive Stars: Supernovae and Gamma-ray Bursts

Unique methods for on-orbit structural repair, maintenance, and assembly

This paper reviews the MDA independent research and development (IRAD) efforts since 1986 in the development of two distinctly different approaches to on-orbit tube repair: (1) one-piece mechanical tube fittings that are forced, under pressure, onto the tube outer surface to effect the repair; and (2) electron beam weldings as demonstrated with the Paton-developed universal hand tool (UHT) space welding system for the repair of fluid lines and tubular components. Other areas of potential on-orbit repair using the UHT include damage to the flat or curved surfaces of habitation modules and truss assemblies. This paper will also address MDA evaluation of the Paton UHT system for on-orbit coating, cleaning, brazing, and cutting of metals. MDA development of an on-orbit compatible nondestructive evaluation (NDE) system for the inspection of tube welds is an important part of this complete space welding capability and will be discussed in a separate paper

Which weather and water conditions affect the biodiversity and abundance of macroinvertebrates the most?

Macroinvertebrates are important biological monitors that play a valuable role in the metabolism of freshwater food chains. Previous studies have suggested that conditions such as dissolved oxygen, pH, water temperature, precipitation, and air temperature can affect the abundance of macroinvertebrates which can in turn affect the health of freshwater ecosystems. This research aimed to find the relationship between macroinvertebrate biodiversity and various environmental conditions in freshwater ecosystems. Weather data was taken from a weather station at Lancer Park and water data was taken on-site at Wilson stream, both locations in Farmville, Virginia. Sample collection and identification occurred twice a week for five weeks. Macroinvertebrates were collected using a depolled net and then stored for identification. It is expected that moderate weather conditions and above average precipitation will be associated with higher observed macroinvertebrate biodiversity. However, if the weather conditions are cooler with below average precipitation there will be a lower biodiversity of aquatic macroinvertebrates

Development of a Smartphone Application to Enable Remote Monitoring in the Outpatient Management of Cirrhotic Ascites

Patients who develop hepatic decompensation with ascites have a poor prognosis and often experience other complications including spontaneous bacterial peritonitis, hepatic encephalopathy and variceal bleeding. We hypothesised that smartphone (SP)-enabled remote monitoring of patients with ascites may enable early detection of infection and acute decompensation, facilitate timely intervention and improve patient outcomes. Aim:  We aimed to design, develop and implement a remote monitoring system (RMS) for outpatients with cirrhotic ascites. Method: We undertook surveys with patients and hepatologists to quantify the demand for a RMS and identify issues regarding implementation. A smartphone and a web-based application were developed as a RMS. Patients used the RMS in a 6-week prospective non-randomised trial.  Results: We surveyed 27 patients (mean age 56 years, 18 (67%) were male, 16 (59%) had Childs Pugh B cirrhosis, and 20 (74%) had a history of alcoholic liver disease) and 5 hepatologists. There were 19 patients (70%) who reported that they would use a RMS. The RMS was used by 10 patients for a mean 53.8days (11-70), who entered 20.6 (0-71) updates. A total of 18 automated alerts occurred. 22% of automated alerts resulted in clinically significant changes to management, such as inpatient admission n=1 (6%), early outpatient appointment n=1 (6%) and reinforced adherence n=2 (11%). Conclusion:   We have successfully designed an internet-enabled RMS for outpatients with cirrhotic ascites that could be used as an adjunct to existing outpatient services. Future studies will optimise the alert thresholds, assess long-term patient adoption and quantify clinical impact

Why you Can’t Use Water to Make Cryoporometric Measurements of the Pore Size Distributions in Meteorites – or in High Iron Content Clays, Rocks or Concrete.

Many porous materials have high susceptibility magnetic gradients in the pores, due to the presence of iron or other magnetic materials. Thus if probe liquids are placed in the pores they exhibit fast decaying signals with a short T2*. Usually the actual T2 of the liquids is also reduced, due the presence of paramagnetic ions in the pore walls. The usual solution in NMR is to measure an echo (or echo train) at short times. However, recent work [J. Phys.: Condens. Matter 19, 415117, 2007.] has shown that water/ice systems near a pore wall form rotator phase plastic ice, with T2 relaxation times in the region of 100 to 200 ms. Thus if a NMR cryoporometric measurement is attempted with a measurement time significantly less than 1 or 2 milli-seconds, the result is to make a measurement based on the phase properties of the brittle to plastic ice phase transition, not that of the brittle ice to water phase transition. This gives rise to artefacts of small pore sizes that may not actually be present. This work successfully uses a-polar liquids instead

Practical corn sampling and hand sieving procedures

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