This study examines the effects of a low oxygen environment, in concert with fluctuating temperature and salinity conditions, on the nearshore depth distributions (0-1 m) and flood tide movements of juvenile chinook (Oncorhynchus tshawytscha) and chum (O. keta) salmon. Comparisons are made between an unpolluted and a sewage polluted estuarine intertidal flat in the Fraser River estuary, British Columbia, the polluted area being characterized by the regular occurrence of low dissolved oxygen levels. Results are based on 380 beach seine samples taken between April and June of 1984. In general, chum and chinook salmon of increasing length were captured in increasing depths, though this pattern was modified by seasonal changes in water temperature. Low dissolved oxygen conditions in deeper waters may have been responsible for the presence of larger, and often sluggishly swimming fish in higher oxygenated surface water layers or in shallow waters near the shore. In both areas, the risk of aerial predation was high. On a flood tide, the likelihood of capturing a chinook salmon was reduced as temperatures increased and oxygen levels decreased. A combination of avoidance behaviour and a regularity in the movement patterns of chinook onto the study area in the later stages of the flood tide may account for their rare occurrence in low oxygen concentrations (<6 mg/1) and high temperatures (>20 °C). Fish mortalities were most likely to occur on the ebb tide when fish were forced into waters of low oxygen content by the drainage patterns characteristic of the polluted study area. Though wide ranges in salinity were recorded on both tidal flats, this factor was not strongly correlated to Chinook distributions. However, significantly higher salinity levels in the unpolluted area may account for the greater numbers of chum salmon captured there. An understanding of the influence of estuarine water quality conditions on the distribution of juvenile salmonids may assist in the identification of significant sources of mortality in their early marine life. This knowledge is particularly important in the evaluation of water quality changes as caused by human activity. / Science, Faculty of / Zoology, Department of / Graduate

Oxygen is known to sensitize X-irradiated cells to lethal radiation damage. At low ambient oxygen tensions, however, the molecular mechanisms of the sensitization process and the metabolic requirements of the cell may be forced to compete for the cellular oxygen supply. The effect of cell respiration on the availability of intracellular oxygen during irradiation was consequently investigated by comparing the radiosensitivities of respiring and non-respiring cells. Cultured mammalian cells were irradiated in single cell suspensions and thin film monolayers at respiration inhibiting (4°C) and at normal cell culturing (37°C) temperatures. Due to oxygen equilibration and radiolytic depletion problems, the results of the suspension culture experiments were inconclusive. By subsequently analyzing the diffusive mass transfer of oxygen in the suspension medium, the stirrer flask was determined to be an inappropriate culture vessel in which to irradiate cells at constant low oxygen concentrations. A thin film cell culture system in which the oxygen concentrations to which the cells were exposed during irradiation could be more accurately controlled was then developed. A comparison of the oxygen enhanced radiosensitivities of the respiring and non-respiring cells in thin film monolayers suggested that the metabolic depletion of oxygen at low oxygen tensions has a significant effect on the local and intracellular oxygen distribution. These effects are representative of those that would be produced if respiration induced oxygen gradients existed inside and immediately around respiring cells. The magnitude of the differential radiosensitivities was found to be dependent on cell shape and to have values that agreed very well with theoretical predictions based on the existence of such gradients. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

The finding that the performance of a response during periods of drug exposure facilitates the development of tolerance to the effects of the drug on that response is commonly referred to as contingent drug tolerance. Contingent tolerance is typically demonstrated in before-and-after design experiments. One group of subjects receives drug before the performance of the criterion response (drug-before-test condition) and a second group of subjects receives drug after the performance of the criterion response (the drug-after-test condition). The usual finding is that substantial tolerance develops in the drug-before-test condition, but no tolerance whatsoever develops in the drug-after-test condition. Such demonstrations of contingent tolerance have led to the drug-effect theory of tolerance: the theory that tolerance to a particular drug effect is an adaptive response to the experience of that particular drug effect. The purpose of this thesis was to clarify the relation between drug exposure, drug effects, and the development of tolerance. Several experiments have demonstrated that no tolerance whatsoever develops to anticonvulsant drug effects if convulsive stimulation is administered prior to each drug injection (drug-after-test condition), rather than afterwards (drug-before-test condition). Be that as it may, a different experimental design was used in Experiments 1 and 2 to show that small amounts of tolerance develop in the absence of concurrent convulsive stimulation. Rats that received either 3 intraperitoneal injections of diazepam (5.0 mg/kg) per day for 10 days (Experiment 1) or 1 gastric intubation of ethanol (5 g/kg) for 21 days (Experiment 2) were significantly more tolerant than vehicle controls; however, the tolerance could be detected only by a sensitive savings measure. The purpose of Experiment 3 was to test a novel interpretation for the inconsistency between Experiments 1 and 2 on the one hand and the repeated failure to observe tolerance to anticonvulsant drugs following drug exposure without concurrent convulsive stimulation in the drug-after-test condition of before-and-after experiments on the other. This hypothesis is that small amounts of tolerance do develop following each drug injection in the drug-after-test condition but that it is dissipated the next day by the convulsive activity experienced in the absence of the drug. To test this hypothesis, one group of amygdala-kindled rats received 15 diazepam injections (2.5 mg/kg) each before a convulsive stimulation, one group received 15 diazepam injections each after a convulsive stimulation, one group received 15 diazepam injections with no convulsive stimulation, and one group received 15 vehicle injections either with or without convulsive stimulations. The drug-before-stimulation rats developed substantial tolerance as has been frequently reported, and the hypothesis was confirmed by the finding that the drug-only rats developed tolerance significantly faster than the rats in the drug-afterstimulation group and the rats in the vehicle-control group. The results of these experiments make two important points. First, tolerance develops following drug exposure even when the criterion response is not performed during drug exposure —albeit substantially less than when it is performed. Presumably, this is because a few of the neural circuits that are active during a convulsion are spontaneously active following the drug administration. Second, the reason why the subjects in the drug-after condition display no evidence of tolerance is because the drug-free performance of the criterion response prior to each drug exposure causes any tolerance that has developed to dissipate. / Arts, Faculty of / Psychology, Department of / Graduate

This investigation was initiated to study the effect of CO₂ on phytochrome-mediated morphogenesis in flowering and seed germination. Removal of CO₂ by flushing the plant environment with CO₂-free air inhibited the red light interruption effects on flowering in Xanthium pennsylvanicum and on seed germination in Lactuca sativa cv Grand Rapids. Further experiments were done to investigate the involvement of CO₂ exchange in the effects of night interruptions on flowering in Xanthium. ¹⁴CO₂ feeding trials showed that red light given for 5 minutes caused a net increase in ¹⁴C activity in the ethanol soluble fraction when ¹⁴CO₂ was fed during the light treatment. There was no effect of red light on the extent of ¹⁴CO₂ fixation in the dark period immediately following red light. The types of free amino acids recovered after paper chromatography were essentially the same after ¹⁴CO₂ feedings in darkness, red light, and far red light following red light. However, there was a considerable increase in ¹⁴C activity in most of the amino acids in leaves given red light interruption, and the amount further increased when far red light was given following the red light. The extent of ¹⁴C label in tyrosine, valine and leucine was essentially the same in all the three treatments. In CO₂-exchange experiments using the IRGA, brief red or far red light treatments were applied to Xanthium plants under inductive dark periods and the subsequent flowering response was assessed according to bud morphology. The occurrence of flowering depended on the timing, wavelength and intensity of the light treatments, and on the CCL concentration during the light treatments. CO₂ exchange was measured during the night interruptions in single attached leaves. CO₂ exchange was influenced by the conditions during the night interruptions, but there was no apparent correlation between the pattern of CO₂ exchange observed and the subsequent flowering response. It appears that the action of during night interruptions is not associated with the exchange of during the night interruption. In an attempt to investigate other possible roles of CO₂, experiments were done with light sensitive lettuce and Amaranthus retroflexus L. seeds. These experiments pertained to changes in pH of the incubation medium and CO₂ concentration simultaneously. Germination was strongly promoted at pH 4.0 but the promotion diminished with increases in pH and did not occur at pH 7.5. The response of germination to red irradiation was suppressed by CO₂ removal and enhanced by CO₂ enrichment in air or atmospheres. There was a close similarity between the pH effects on percentage germination and pH dependence of the CO₂ /HCO₃ - equilibrium. Transfer experiments, in which lettuce seeds were exchanged between buffers of pH 4.0 and pH 3.0, showed that the red/far red photo-transformation of phytochrome v/as independent of pH. Low pH, however, was required for onset of germination following red irradiation. Thereafter, pH between 4.0 and 8.0 did not limit the progress of germination. It is postulated that following red irradiation, a product develops which is distinguishable from the Pfr form of phytochrome. The product is stable at pH 8.0 and at pH 4.0 it acts to promote germination. / Science, Faculty of / Botany, Department of / Graduate

The chloride current-voltage characteristics of the membrane of sartorius fibers from Xenopus laevis were studied using a three microelectrode voltage clamp system. In fibers with normal resting potentials (-70 to -90 mV) and in fibers depolarized in 115 mM KC1 (resting potential -20 mV) the direction and degree of steady state rectification depended on extracellular pH. In alkaline solutions (pH 8.4) the current rectified outwards; with large hyperpolarizations the current recorded in normally polarized fibers was sometimes seen to diminish as the voltage was made extremely negative (the current-voltage relation exhibited a negative slope). In the depolarizing region (in depolarized fibers) the slope of the I-V relation became constant (limiting conductance) in alkaline solutions. In acid solutions (pH 5.4) the current rectified inwards with hyperpolarization and reached a limiting value with depolarization. Chloride currents decay ('inactivate') following changes of membrane potential from the resting potential (for both polarized and depolarized fibers). The kinetics of current relaxation exhibited voltage-dependent time constants depending on the size of the voltage step with a sensitivity of about -1.5 msec/mV but were independent of absolute membrane potential and external pH. Inactivation of chloride conductance was studied in two-pulse (conditioning (v₁) and test (V₂), pulses) voltage clamp experiments. In variable experiments the dependence of the initial current at the onset of was sigmoidally related to (inactivation relation). The slope of the inactivation relation was twice as steep in acid as in alkaline solutions, but was independent of the resting potential. In variable V₂ experiments, the current-voltage relation was linear over a wide voltage range and for different values of V₁, the instantaneous I-V relations converged in the outward current region; they also had zero-current potentials that became increasingly negative with respect to the holding potential as V₁ was made negative. Instantaneous chloride currents and the kinetics of current relaxation were found to depend on initial conditions when the membrane potential was changed under non-stationary conditions. The inactivation and recovery of initial current had similar timecourses as did the prolongation and recovery of the time constants. Initial currents recovered from conditioning with an exponential or sigmoid timecourse. Relaxation time constants exhibited a similar recovery pattern. The decline of initial current was initially exponentially dependent on the duration of conditioning. The time constant increased sigmoidally, or exponentially as the duration of conditioning increased. Using the data from variable conditioning step and variable test step experiments a manifold (or state space representation) was constructed that enables much of the current-voltage behavior of the chloride permeation system to be predicted. Currents recorded in voltage clamp experiments can be visualized as time-dependent flows along trajectories that are determined by the voltage. The rectification of the steady state and instantaneous current-voltage relations are related to the dispersion of the trajectories. The dependence of time constants of current transients can also be accounted for by the manifold. The results are examined in light of models for channel behavior. The instantaneous I-V characteristics exhibit some properties of channels of the electrodiffusion type. The steady state current-voltage relations are qualitatively similar to those of a model incorporating a particle within the chloride channel that either blocks or unblocks it depending on the extracellular pH. The dependence of relaxation kinetics on the size of the voltage step and on initial conditions suggest the participation of a molecule acting in a catalytic role controlling the relaxation of current transients. / Science, Faculty of / Mathematics, Department of / Unknown

Anaerobic threshold speed (VTAM) was determined for 20 male university students using a continuous treadmill protocol. The onset of anaerobiosis was determined by analyzing excess CO₂ elimination. The following week, all subjects ran at the VTAM median speed of 7.25 miles per hour for 10 minutes. Recovery oxygen consumption was monitored after this run. Application of double exponential equations by computer and subsequent integration, calculated Total, Alactic, and Lactic Oxygen Debts. Subjects who ran above their VTAM (group L-VTAM) had significantly (p < .05) higher total, lactic and alactic debts than those subjects who ran below their VTAM (group H-VTAM). The total debt showed a significant (p < .05) negative correlation (r=-.77) to in; group L-VTAM. This appears to be due to the increasing lactic debt, that was also significantly (p < .05) negatively correlated (r=-.73) to VTAM. Group H-VTAM did not exhibit this characteristic. This study demonstrates that VTAM is a critical factor in determining oxygen debt and therefore, work above this point results in the onset of metabolic acidosis, which may limit the optimal running speed for a given distance. / Education, Faculty of / Kinesiology, School of / Graduate

This thesis deals with the importance of salinity to the distribution of three chironomid species of the genus Chironomus (C. anthracinus. C. athalassicus. and C. tentans). Research to date suggests that salinity and coexistence problems are the major factors influencing the distribution of the chironomid fauna of fresh and saline lakes in the Cariboo and Chilcotin areas of central British Columbia. The difference in the distribution of these three Chironomus species is particularly interesting. The investigation of the importance of salinity to their distribution consisted of a study of (i) the salinity tolerance of each species, (ii)the regulation of the haemolymph, and (iii) the influx and efflux of sodium and chloride ions. Several conclusions were drawn from the investigation. A difference in the salinity tolerance of each species was found in the laboratory: C. anthracinus and C. tentans did not survive at lake water conductivities above 9000 micro-o mhos/cm at 25 C, C. athalassicus survived in lake water conductivities at least as high as 15»000 micromhos/cm at o 25 C. Temperature affected the survival of each species in a similar way; at high temperatures survival time decreased. Sodium, potassium, and chloride as well as the concentration of the haemolymph were regulated by the three species at low salinities. C. athalassicus was the only species able to conform at higher external concentrations. C. athalassicus had a low sodium affinity and a powerful sodium uptake system compared to the other species. Chloride affinity and the power of the uptake system exceeded that of C. anthracinus and C. tentans. The general conclusion reached was that salinity does affect the distribution of the three Chlronomus species. More research is called for in this and related areas in order to more fully understand the distribution of the chironomid fauna. / Science, Faculty of / Zoology, Department of / Graduate

Evidence that recoilless emission and absorption exist may be shown by an experiment in which the source gamma rays are allowed to pass through a suitable absorber to a detector.

acase@tulane.edu / Rational, synthetic design is implemented in a systematic study of the effect of host shape and properties and manifestations of the reverse Hofmeister effect. Hofmeister specific effects were observed at the molecular level wherein it was shown that key to the effectiveness of some “salting-in” anions is their complementarity to hydrophobic cavities and other binding surfaces. A gamut of responses was observed across a range of hosts possessing different structural and functional motifs. These observations were typically manifest at a relatively low (<20 mM) critical precipitation concentration (CPC). Furthermore, it was shown that at low concentrations, typical observations of screening effects are not observed, and binding-site competition is a predominant factor when multiple anions are present in solution. In terms of quantifying the ion recognition sites of different, similarly charged hosts there is little difference in anion affinity, but large differences are observed in 1/CPC values. Thus, subtle changes in the recognition site have dramatic changes in terms of manifestations of the reverse Hofmeister effect. This is (to the authors best knowledge) the first example of a systematic study sequentially modifying small molecular hosts and utilizing them to study reverse Hofmeister trends. In total 12 hosts and 6 host-guest complexes were examined. These studies demonstrate applications of the reverse Hofmeister effect to generate single crystal X-ray structures, with potential applications in protein and small molecule purifications, separations, and crystallizations. / 1 / Jacobs Jordan

Data-driven decision making is an integral part of higher education and it needs to be rooted in strong methodological and statistical practices. Key practices include the use and interpretation of effect sizes as well as a correct understanding of null hypothesis significance testing (NHST). Therefore, effect size reporting and interpreting practices in higher education journal articles represent an important area of inquiry. This study examined effect size reporting and interpretation practices of published quantitative studies in three core higher education journals: Journal of Higher Education, Review of Higher Education, and Research in Higher Education. The review covered a three-year publication period between 2013 and 2015. Over the three-year span, a total of 249 articles were published by the three journals. The number of articles published across the three years did not vary appreciably. The majority of studies employed quantitative methods (71.1%), about a quarter of them used qualitative methods (25.7%), and the remaining 3.2% used mixed methods. Seventy-three studies were removed from further analysis because they did not feature any quantitative analyses. The remaining 176 quantitative articles represented the sample pool. Overall, 52.8% of the 176 studies in the final analysis reported effect size measures as part of their major findings. Of the 93 articles reporting effect sizes, 91.4% of them interpreted effect sizes for their major findings. The majority of studies that interpreted effect sizes also provided a minimal level of interpretation (60.2% of the 91.4%). Additionally, 26.9% of articles provided average effect size interpretation, and the remaining 4.3% of studies provided strong interpretation and discussed their findings in light of previous studies in their field.