Impacts of flow releases on invertebrate drift and juvenile Chinook salmon (Oncorhynchus tshawytscha) diet on the Trinity River below Lewiston Dam

Benthic macroinvertebrate (BMI) drift, species composition and abundance are specific to local hydrologic and habitat conditions, which can restrict or enhance availability to salmonids as a food resource. Currently, a knowledge gap exists on the Trinity River (northern California) in how flow releases from Lewiston Dam potentially impact BMI drift and feeding opportunities for juvenile salmonids. Samples of BMIs from drift, benthos, and diets of juvenile Chinook salmon (Oncorhynchus tshawytscha) were collected from two sites in the upper Trinity River February-April 2018, during stable flow conditions (~8 ) and two increased flow conditions peaking at ~50 . Chironomidae (Diptera) and Baetidae (Ephemeroptera) were dominant BMI taxa in the drift, benthos and diets. Although contributions to biomass were more even across BMI taxa in the drift, biomass consumed by fish was dominated by Chironomidae and Baetidae at both study sites. BMI taxonomic composition was more similar between benthic, drift and diet samples at the upstream study site below Lewiston Dam, whereas compositional similarities diverged during peak discharge conditions at the downstream study site. Although standardized drift rates (ex. mg/m3) did not increase with increased flow, the total export of BMI drift increased significantly with increased flow (

P4_7 Make a Brake for It!

AbstractThe paper investigates the plausibility of using a solar sail to reduce the orbital radius of a satellite around Mars instead of rocket thrusters. This is done by calculating the surface area of sail needed to lower the orbital radius from 3657km to 3517km by deploying the sail for a quarter of the orbit. The resulting surface area is 2.5x10 km2, which is impractical as a replacement for current methods

P4_2 Beam Me Up

The effects of sending a laser powered platform to low Earth orbit are investigated. We consider the effects of drag, attenuation by the atmosphere and divergence of the laser beam. It is found that a 1000kg platform could be accelerated to an altitude of 200km using an average laser power of 1.8 terawatts; however it is unfeasible to extend this argument to a much more massive space shuttle sized object

P4_3 Total Free Fall

This paper analyses the logistics of The Fall, a fictional elevator through the Earth in the 2012 film Total Recall. In the film, it is claimed that the elevator can make its journey in 17 minutes by free falling through the centre of the planet. By modelling the actual free fall of an object in a vacuum through the Earth, it is shown that this trip would in fact take over 42 minutes. Drag forces were then considered, showing that without an external force The Fall would enter damped harmonic motion and would never reach its destination

P4_6 A Good Hose Down

This paper investigates the maximum pressure of a fire hydrant that a human can withstand before losing control due to the impulse at the hose aperture. The effects of static friction and the maximum grip force are compared, and it is found that at a hydrant pressure of 131KPa, a human will lose grip of the hose, whereas a pressure of 140KPa is required to cause the handler of the hose to begin to slide backwards

Retirees' Attitudes Toward Mental Illness Treatment: A Life-Course Perspective

This purpose of this dissertation was to examine the attitudes of retirees toward mental illness treatment. Secondary data from the Survey Research Center at the University of North Texas was utilized for this study. The focus was on the influence that gender, income, education, race/ethnicity, personal experience, fear, goodwill, and social control might have had on retirees' attitudes toward mental illness treatment. An n = 225 was selected out of the existing data to serve as the sample population. Binary logistic regression was utilized to analyze the data. Results indicated that the obtained significant findings were consistent with existing literature

Back seat driving: hindlimb corticospinal neurons assume forelimb control following ischaemic stroke

Whereas large injuries to the brain lead to considerable irreversible functional impairments, smaller strokes or traumatic lesions are often associated with good recovery. This recovery occurs spontaneously, and there is ample evidence from preclinical studies to suggest that adjacent undamaged areas (also known as peri-infarct regions) of the cortex ‘take over' control of the disrupted functions. In rodents, sprouting of axons and dendrites has been observed in this region following stroke, while reduced inhibition from horizontal or callosal connections, or plastic changes in subcortical connections, could also occur. The exact mechanisms underlying functional recovery after small- to medium-sized strokes remain undetermined but are of utmost importance for understanding the human situation and for designing effective treatments and rehabilitation strategies. In the present study, we selectively destroyed large parts of the forelimb motor and premotor cortex of adult rats with an ischaemic injury. A behavioural test requiring highly skilled, cortically controlled forelimb movements showed that some animals recovered well from this lesion whereas others did not. To investigate the reasons behind these differences, we used anterograde and retrograde tracing techniques and intracortical microstimulation. Retrograde tracing from the cervical spinal cord showed a correlation between the number of cervically projecting corticospinal neurons present in the hindlimb sensory-motor cortex and good behavioural recovery. Anterograde tracing from the hindlimb sensory-motor cortex also showed a positive correlation between the degree of functional recovery and the sprouting of neurons from this region into the cervical spinal cord. Finally, intracortical microstimulation confirmed the positive correlation between rewiring of the hindlimb sensory-motor cortex and the degree of forelimb motor recovery. In conclusion, these experiments suggest that following stroke to the forelimb motor cortex, cells in the hindlimb sensory-motor area reorganize and become functionally connected to the cervical spinal cord. These new connections, probably in collaboration with surviving forelimb neurons and more complex indirect connections via the brainstem, play an important role for the recovery of cortically controlled behaviours like skilled forelimb reachin