京都大学 / 新制・課程博士 / 博士(理学) / 甲第23042号 / 理博第4719号 / 新制||理||1676(附属図書館) / 京都大学大学院理学研究科生物科学専攻 / (主査)教授 沼田 英治, 教授 曽田 貞滋, 准教授 森 哲 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DGAM

In this paper, binaural beats were used as stimuli to induce Gamma neural activity in the brains of 18 participants with the purpose to see if the effect enhanced memory and/or speech perception. Participants conducted a word-list recall task, followed by a speech-in-noise task under three conditions: before Gamma stimulus, after Gamma stimulus, and after a placebo stimulus. The results showed that the method works to boost Gamma neural activity, but that neither memory nor speech-perception was significantly affected by the stimulus. The conclusion is that binaural beats is unreliable as a method to enhance memory and speech-perception in humans.

A selective combination of the principles of a thermal mass flow meter and constant temperature anemometry was used to develop a solid mass flow meter that improves significantly on the flow meter developed by De Vos et al (2010). The flow meter has a measurement plate that is kept at a constant temperature. Due to conductive heat transfer between the entrained solids and the measurement plate, additional power is needed to maintain the plate at this setpoint temperature value. This additional power was correlated against the average solids flow rate. The calibration curve shows a linear relationship between the power measurement and the entrainment flux for entrainment fluxes between 3.4 x 10-4 kg/(m2.s) and 7.5 x 10-3 kg/(m2.s). Deviation from a linear response at lower entrainment fluxes may be caused by a longer residence time of fine particles on the measurement plate due to lower shear forces. At higher entrainment fluxes the power measurements were unreliable due to poor temperature control. The turndown ratio of the linear section of the calibration curve is approximately 3 times that of the linear part of the calibration curve of the flow meter developed by De Vos et al (2010). Even further improvement is possible with better temperature control. In a case study to test the applicability of the flow meter to measure changes in entrainment rate associated with hydrodynamic properties other than a change in gas superficial velocity, small amounts of ethanol were dosed to the inlet air. The continuously measured entrainment rate increased at lower ethanol dosing rates but decreased as the dosing rate of ethanol was increased. The increase in entrainment rate may be explained by a reduction in static electricity in the bed, while the decrease at higher dosing rates may be as a result of increased powder cohesivity. / Dissertation (MEng)--University of Pretoria, 2012. / Chemical Engineering / unrestricted

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Management agencies documented a decline in the mountain whitefish (Prosopium williamsoni) population on the Big Lost River, and unscreened diversions were recognized as a potential factor for this decline. Research suggests the Big Lost River mountain whitefish population is genetically unique, and it has been petitioned for protection under the Endangered Species Act. In 2007, a basin-wide synopsis of diversions was conducted to describe relative entrainment and identify diversions that entrained the most mountain whitefish. This larger scaled synopsis facilitated a more precise assessment of entrainment by a subset of diversions in 2008. In 2008, the volume that was diverted and the available stream-flows were assessed to identify correlations between discharge and increased entrainment. Lastly, a stage-structured population matrix model was used to describe the potential effect that entrainment is having on the mountain whitefish population. Entrainment was evaluated in canals using multiple-pass electrofishing depletions in conjunction with block-nets. Entrainment was estimated using simple or stratified random population estimates. Entrainment varied widely among diversions and between water years. Variations in entrainment were attributed to seasonal patterns, population densities, and the physical characteristics of the diversion. A positive correlation was identified (R2 = 0.81) between the number of mountain whitefish entrained and the volume of water diverted annually. I observed substantial numbers of fish entrained by two diversions on the upper Big Lost River. I illustrate how reducing entrainment at these diversions will increase recruitment to adulthood and increase the viability of the population overall.

We examined the circadian rhythms of locomotor activity in three spider species in the Family Theridiidae under light–dark cycles and constant darkness. Contrary to previous findings in other organisms, we found exceptionally high variability in endogenous circadian period both within and among species. Many individuals exhibited circadian periods much lower (19–22 h) or much higher (26–30 h) than the archetypal circadian period. These results suggest relaxed selection on circadian period as well as an ability to succeed in nature despite a lack of circadian resonance with the 24-h daily cycle. Although displaying similar entrainment waveforms under light–dark cycles, there were remarkable differences among the three species with respect to levels of apparent masking and dispersion of activity under constant dark conditions. These behavioral differences suggest an aspect of chronotype adapted to the particular ecologies of the different species.

Circadian clocks are vital to the proper functioning of organisms’ internal processes and behavioral outputs and typically have endogenous periods that approximate (within 1-2 hours) the 24-hour solar day. Clocks that deviate significantly from about 24 hours are often associated with metabolic syndromes or other disease states. For instance, organisms with near-24-hour clocks have higher survivorship under 24-h light:dark (LD) cycles than with 22- or 26-hour cycles. Likewise, mutant organisms with 22-hour clocks survive better under 22-h cycles but fare poorly under 24- and 26-h cycles. In other words, organisms suffer if their circadian clocks do not “resonate” with environmental cycles. Organisms fail to synchronize (entrain) their activity with non-resonant LD cycles and this failure typically leads to a number of physiological disruptions. Interestingly, several spider species have endogenous circadian periods that deviate by several hours from the period of the Earth’s solar day. The object of the present study is to investigate whether the phenomenon of circadian resonance also pertains to these atypical spider circadian rhythms. We investigated three spider species, two of which have internal periods (τ) significantly different from 24 hours. Approximately 50 individuals of each species of spider (Frontinella communis: τ=29.05±0.62 hours; Metazygia wittfeldae: τ=22.74±0.24h; and Cyclosa turbinata: τ=18.54±0.28h) were placed into chambers with periods of 19 (9.5:9.5h L:D), 24 (12:12h L:D), or 29 hours (14.5:14.5h L:D). If resonance is pertinent for spiders, we would expect survivorship to decrease in non-resonant LD cycles. Instead, no spider species exhibited decreased longevity in non-resonant L:D cycles. These findings contradict all previous research into circadian resonance and suggest that spiders do not suffer the costs of extreme desynchronization. In a second experiment, 10-11 spiders from each species were placed into infrared activity monitors to determine if their locomotor activity could entrain to (synchronize with) the three different LD cycles. Individuals from all three spider species entrained to all LD period lengths, again in contrast with prior research in other species. These results indicate that spider circadian clocks have highly unusual limits of entrainment and suggest a remarkable level of plasticity in their release from the selective pressure to maintain an internal period of approximately 24 hours.

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