Mollusca Non-Grata: The influence of top-down control and residence time on the abundance, distribution, and behavior of non-native marine snails in Washington State

Thesis (Ph.D.)--University of Washington, 2016-06

Analysis of an Intervention to Reduce Truck Drivers' Exposure to Whole-Body Vibration

Thesis (Master's)--University of Washington, 2016-06

Enhanced spin injection efficiency in ferromagnet/semiconductor tunnel junctions

Within the ballistic transport picture, we have investigated the spin-polarized transport properties of a ferromagnetic metal/two-dimensional semiconductor (FM/SM) hybrid junction and an FM/FM/SM structure using quantum tunnelling theory. Our calculations indicate explicitly that the low spin injection efficiency (SIE) from an FM into an SM, compared with a ferromagnet/normal metal junction, originates from the mismatch of electron densities in the FM and SM. To enhance the SIE from an FM into an SM, we introduce another FM film between them to form FM/FM/SM double tunnel junctions, in which the quantum interference effect will lead to the current polarization exhibiting periodically oscillating behaviour, with a variation according to the thickness of the middle FM film and/or its exchange energy strength. Our results show that, for some suitable values of these parameters, the SIE can reach a very high level, which can also be affected by the electron density in the SM electrode.

Children and war

Children bear disproportionate consequences of armed conflict. The 21st century continues to see patterns of children enmeshed in international violence between opposing combatant forces, as victims of terrorist warfare, and, perhaps most tragically of all, as victims of civil wars. Innocent children so often are the victims of high-energy wounding from military ordinance. They sustain high-energy tissue damage and massive burns - injuries that are not commonly seen in civilian populations. Children have also been deliberately targeted victims in genocidal civil wars in Africa in the past decade, and hundreds of thousands have been killed and maimed in the context of close-quarter, hand-to-hand assaults of great ferocity. Paediatricians serve as uniformed military surgeons and as civilian doctors in both international and civil wars, and have a significant strategic role to play as advocates for the rights and welfare of children in the context of the evolving 'Laws of War'. One chronic legacy of contemporary warfare is blast injury to children from landmines. Such blasts leave children without feet or lower limbs, with genital injuries, blindness and deafness. This pattern of injury has become one of the post-civil war syndromes encountered by all intensivists and surgeons serving in four of the world's continents. The continued advocacy for the international ban on the manufacture, commerce and military use of antipersonnel landmines is a part of all paediatricians' obligation to promote the ethos of the Laws of War. Post-traumatic stress disorder remains an undertreated legacy of children who have been trapped in the shot and shell of battle as well as those displaced as refugees. An urgent, unfocused and unmet challenge has been the increase in, and plight of, child soldiers themselves. A new class of combatant comprises these children, who also become enmeshed in the triad of anarchic civil war, light-weight weaponry and drug or alcohol addiction. The International Criminal Court has outlawed as a War Crime, the conscription of children under 15 years of age. Nevertheless, there remain more than 300 000 child soldiers active and enmeshed in psychopathic violence as part of both civil and international warfare. The typical profile of a child soldier is of a boy between the ages of 8 and 18 years, bonded into a group of armed peers, almost always an orphan, drug or alcohol addicted, amoral, merciless, illiterate and dangerous. Paediatricians have much to do to protect such war-enmeshed children, irrespective of the accident of their place of birth. Only by such vigorous and maintained advocacy can the world's children be better protected from the scourge of future wars.

Effector ExoU from the type III secretion system is an important modulator of gene expression in lung epithelial cells in response to Pseudomonas aeruginosa infection

Pseudomonas aeruginosa is an important pathogen in immunocompromised patients and secretes a diverse set of virulence factors that aid colonization and influence host cell defenses. An important early step in the establishment of infection is the production of type III-secreted effectors translocated into host cells by the bacteria. We used cDNA microarrays to compare the transcriptomic response of lung epithelial cells to P. aeruginosa mutants defective in type IV pili, the type III secretion apparatus, or in the production of specific type III-secreted effectors. Of the 18,000 cDNA clones analyzed, 55 were induced or repressed after 4 It of infection and could be classified into four different expression patterns. These include (i) host genes that are induced or repressed in a type III secretion-independent manner (32 clones), (ii) host genes induced specifically by ExoU (20 clones), and (iii) host genes induced in an ExoU-independent but type III secretion dependent manner (3 clones). In particular, ExoU was essential for the expression of immediate-early response genes, including the transcription factor c-Fos. ExoU-dependent gene expression was mediated in part by early and transient activation of the AN transcription factor complex. In conclusion, the present study provides a detailed insight into the response of epithelial cells to infection and indicates the significant role played by the type III virulence mechanism in the initial host response.

Food choice in Siganus fuscescens: influence of macrophyte nutrient content and availability

Using multiple-choice feeding experiments, the selection of six species of macrophytes by the herbivorous rabbitfish Siganus fuscescens was examined. The rabbitfish showed distinct food choice in the laboratory; however, selection of macrophytes by S. fuscescens was not related to their absolute nutrient content (nitrogen, carbon, energy and ash free dry mass). Nutrient assimilation estimates showed that the macrophytes which were most preferred were those that S. fuscescens assimilated best. In S. fuscescens, the macrophytes that were preferred passed through the gut significantly faster than the less preferred species. Gut transit time had a significant effect on the absolute value of a food item in terms of net nutrient gain per unit time. This study showed that food value could be inferred from the absolute nutrient content of the macrophytes. Thus both the ability to assimilate nutrients as well as the absolute nutrient content of macrophytes must be quantified when assessing food value. (C) 2004 The Fisheries society of the British Isles.

Contrary effects of jasmonate treatment of two closely related plant species on attraction of and oviposition by a specialist herbivore

Elevated jasmonic acid (JA) concentrations in response to herbivory can induce wounded plants to produce defences against herbivores. In laboratory and field experiments we compared the effects of exogenous JA treatment to two closely related cabbage species on the host-searching and oviposition preference of the diamondback moth (DBM), Plutella xylostella. JA-treated Chinese cabbage (Brassica campestris) was less attractive than untreated Chinese cabbage to ovipositing DBM, while JA-treatment of common cabbage (B. oleracea) made plants more attractive than untreated controls for oviposition by this insect. Similar effects were observed when plants of the two species were damaged by DBM larvae. In the absence of insect-feeding, or JA application, Chinese cabbage is much more attractive to DBM than common cabbage. Inducible resistance therefore appears to occur in a more susceptible plant and induced susceptibility appears to occur in a more resistant plant, suggesting a possible balance mechanism between constitutive and inducible defences to a specialist herbivore.

Tailored conductivity in ion implanted polyetheretherketone

Ion implantation can be used to confer electrical conductivity upon conventional insulating polymers such as polyetheretherketone (PEEK). We have implanted PEEK films using three different types of ion implantation: conventional inert gas and metal ion implantation, and ion beam mixing. We have applied a number of analytical techniques to compare the chemical, structural and electrical properties of these films. The most effective means of increasing electrical conductivity appears to be via ion beam mixing of metals into the polymer, followed by metal ion implantation and finally, inert gas ion implantation. Our results suggest that in all cases, the conducting region corresponds to the implanted layer in the near surface to a depth of similar to750 Angstrom (ion beam mixed) to similar to5000 Angstrom (metal ion). This latter value is significantly higher than would be expected from a purely ballistic standpoint, and can only be attributed to thermal inter-diffusion. Our data also indicates that graphitic carbon is formed within the implant region by chain scission and subsequent cross-linking. All ion implanted samples retained their bulk mechanical properties, i.e. they remained flexible. The implant layers showed no signs of de-lamination. We believe this to be the first comparative study between different implantation techniques, and our results support the proposition that soft electronic circuitry and devices can be created by conductivity engineering with ion beams. (C) 2004 Elsevier B.V. All rights reserved.

Dynamic force balances for short-duration hypersonic testing facilities

Two force balance techniques for use in hypersonic impulse facilities are compared by measuring the drag force on a 30° semi-apex-angle blunt cone model in a hypersonic shock tunnel at a free stream Mach number of 5.75. An accelerometer-based balance and a stress-wave force balance were tested simultaneously on the same model to measure the drag force. It was found that drag force measurements could be made using both techniques in a flow with a 450-μ s test period. The measured drag forces compared well with the theoretical values estimated using Newtonian theory.

Diel 'tuning' of coral metabolism: physiological responses to light cues

Hermatypic-zooxanthellate corals track the diel patterns of the main environmental parameters temperature, UV and visible light - by acclimation processes that include biochemical responses. The diel course of solar radiation is followed by photosynthesis rates and thereby elicits simultaneous changes in tissue oxygen tension due to the shift in photosynthesis/respiration balance. The recurrent patterns of sunlight are reflected in fluorescence yields, photosynthetic pigment content and activity of the two protective enzymes superoxide dismutase (SOD) and catalase (CAT), enzymes that are among the universal defenses against free radical damage in living tissue. All of these were investigated in three scleractinian corals: Favia favus, Plerogyra sinuosa and Goniopora lobata. The activity of SOD and CAT in the animal host followed the course of solar radiation, increased with the rates of photosynthetic oxygen production and was correlated with a decrease in the maximum quantum yield of photochemistry in Photosystem H (PSII) (Delta F'/F-m'). SOD and CAT activity in the symbiotic algae also exhibited a light intensity correlated pattern, albeit a less pronounced one. The observed rise of the free-radical-scavenger enzymes, with a time scale of minutes to several hours, is an important protective mechanism for the existence and remarkable success of the unique cnidarian-dinoflagellate associations, in which photosynthetic oxygen production takes place within animal cells. This represents a facet of the precarious act of balancing the photosynthetic production of oxygen by the algal symbionts with their destructive action on all living cells, especially those of the animal host.

Feeding preference and deterrence in rabbitfish Siganus fuscescens for the cyanobacterium Lyngbya majuscula in Moreton Bay, south-east Queensland, Australia

Rabbitfish Siganus fuscescens preferences for Lyngbya majuscula collected from three bloom locations in Moreton Bay, Queensland, Australia, were tested along with a range of local plant species in the laboratory. Consumption of L. majuscula by fish did not differ between wild and captive-bred fish (P = 0.152) but did differ between bloom location (P = 0.039). No relationship was found between consumption rates and lyngbyatoxin-a concentration (r(2) = 0.035, P = 0.814). No correlation existed between C : N and proportion of food consumed when all food types were analysed statistically, whereas a clear correlation was observed when L. majuscula was removed from the calculations. In simulated bloom conditions, fish avoided ingestion of L. majuscula by feeding through gaps in the L. majuscula coverage. Both wild and captive-bred S. fuscescens showed a distinct feeding pattern in 10 day no-choice feeding assays, with less L. majuscula being consumed than the preferred red alga Acanthophora spicifera. Lyngbya majuscula however, was consumed in equal quantities to A. spicifera by wild S. fuscescens when lyngbyatoxin-a was not detectable. Wild fish probably do not preferentially feed on L. majuscula when secondary metabolites are present and are not severely impacted by large L. majuscula blooms in Moreton Bay. Furthermore, poor feeding performance in both captive-bred and wild S. fuscescens suggests that they would exert little pressure as a top-down control agent of toxic L. majuscula blooms within Moreton Bay. (c) 2006 The Fisheries Society of the British Isles.

Flight data analysis of the HyShot 2 scramjet flight experiment

The development of scramjet propulsion for alternative launch and payload delivery capabilities has been composed largely of ground experiments for the last 40 years. With the goal of validating the use of short duration ground test facilities, a ballistic reentry vehicle experiment called HyShot was devised to achieve supersonic combustion in flight above Mach 7.5. It consisted of a double wedge intake and two back-to-back constant area combustors; one supplied with hydrogen fuel at an equivalence ratio of 0.34 and the other unfueled. Of the two flights conducted, HyShot 1 failed to reach the desired altitude due to booster failure, whereas HyShot 2 successfully accomplished both the desired trajectory and satisfactory scramjet operation. Postflight data analysis of HyShot 2 confirmed the presence of supersonic combustion during the approximately 3 s test window at altitudes between 35 and 29 km. Reasonable correlation between flight and some preflight shock tunnel tests was observed.

Substantial changes in the genetic basis of tadpole morphology of Rana lessonae in the presence of predators

Predator-induced morphological plasticity is a model system for investigating phenotypic plasticity in an ecological context. We investigated the genetic basis of the predator-induced plasticity in Rana lessonae by determining the pattern of genetic covariation of three morphological traits that were found to be induced in a predatory environment. Body size decreased and tail dimensions increased when reared in the presence of preying dragonfly larvae. Genetic variance in body size increased by almost an order of magnitude in the predator environment, and the first genetic principal component was found to be highly significantly different between the two environments. The across environment genetic correlation for body size was significantly below 1 indicating that different genes contributed to this trait in the two environments. Body size may therefore be able to respond to selection independently in the two environments to some extent.

Effects of anitoxidant supplementation and exercise training on erythrocyte antioxidant enzymes

Erythrocytes transport oxygen to tissues and exercise-induced oxidative stress increases erythrocyte damage and turnover. Increased use of antioxidant supplements may alter protective erythrocyte antioxidant mechanisms during training. Aim of study: To examine the effects of antioxidant supplementation, (alpha-lipoic acid and a-tocopherol) and/or endurance training on the antioxidant defenses of erythrocytes. Methods: Young male Wistar rats were. assigned to (1) sedentary; (2) sedentary and antioxidant-supplemented; (3) endurance-trained; or (4) endurance-trained and antioxidant-supplemented groups for 14 weeks. Erythrocyte superoxide dismutase (SOD), glutathione peroxidase (GPX), and catalase (CAT) activities, and plasma malondialdehyde (MDA) were then measured. Results: Antioxidant supplementation had no significant effect (p > 0.05) on activities of antioxidant enzymes in sedentary animals. Similarly, endurance training alone also bad no effect (p > 0.05). GPX (125.9 2.8 vs. 121.5 3.0 U.gHb(-1), p < 0.05) and CAT (6.1 0.2 vs. 5.6 0.2 U.mgHb-1, p < 0.05) activities were increased in supplemented trained animals compared to non-supplemented sedentary animals whereas SOD (61.8 4.3 vs. 52.0 5.2 U.mgHb(-1), p < 0.05) activity was decreased. Plasma MDA was not different among groups (p > 0.05). Conclusions: In a rat model, the combination of exercise training and antioxidant supplementation increased antioxidant enzyme activities (GPX, CAT) compared with each individual intervention.

Gas and particle dynamics of a contoured shock tube for pre-clinical microparticle drug delivery

We investigate the gas-particle dynamics of a device designed for biological pre-clinical experiments. The device uses transonic/supersonic gas flow to accelerate microparticles such that they penetrate the outer skin layers. By using a shock tube coupled to a correctly expanded nozzle, a quasi-one-dimensional, quasi-steady flow (QSF) is produced to uniformly accelerate the microparticles. The system utilises a microparticle cassette (a diaphragm sealed container) that incorporates a jet mixing mechanism to stir the particles prior to diaphragm rupture. Pressure measurements reveal that a QSF exit period - suitable for uniformly accelerating microparticles - exists between 155 and 220 mus after diaphragm rupture. Immediately preceding the QSF period, a starting process secondary shock was shown to form with its (x,t) trajectory comparing well to theoretical estimates. To characterise the microparticle, flow particle image velocimetry experiments were conducted at the nozzle exit, using particle payloads with varying diameter (2.7-48 mu m), density (600-16,800 kg/m(3)) and mass (0.25-10 mg). The resultant microparticle velocities were temporally uniform. The experiments also show that the starting process does not significantly influence the microparticle nozzle exit velocities. The velocity distribution across the nozzle exit was also uniform for the majority of microparticle types tested. For payload masses typically used in pre-clinical drug and vaccine applications (