No description available.

A study was made on morphological and cytological features of four Rivulariaceae strains from marine, partially saline and freshwater environments using three versions of saline and freshwater media (standard. - Fe. low P). A brackish Anabaena sp. was used for comparison. Subculture to - Fe medium led to marked changes in morphology and cytology. These were (base to apex): a series of new heterocysts apical to the original one. Intra-thylakoldal vacuolation. Lack of cyanophycin granules, presence of polyphosphate granules, pale colour, brown sheath, short hair and low hairiness. With low P medium, the changes were the opposite. Hairs did not form in Calpthrix D253 in saline medium, whether the cultures were in - Fe or low P medium. Downshift from saline to freshwater medium led to the synchronized development of hairs in most trichomes. Whereas the reciprocal upshift led to loss of hairs. The Fe content was studied in three Rivulariaceae and Anabaena in batch culture in high and low P media, which eventually led to Fe- and P- limitation. respectively. The content reached a maximum by 24 h in all strains, decreasing subsequently from 1.80 - 0.06 % dry weight. Siderophore production was tested in four Rivulariaceae and Anabaena in saline and freshwater media. Two Calothrlx strains and Anabaena produced a siderophore in freshwater medium. Influence of Fe status on nitrogenase activity was tested in two Rivulariaceae and Anabaena in saline and freshwater media during batch culture. Peaks of nitrogenase activity in the former came three to five days after the Fe peak, by which stage Fe content had dropped to within the range 0.6 - 0.3 % dry weight. In contrast, peak activity in Anabaena came within a day of the Fe peak. Addition of Fe to Fe-limited cultures led to rapid increase in activity. The significance of these data on morphology, cytology and physiology and possible interactions between Fe- and P-limitation are discussed.

No description available.

The purpose of this thesis is to assess and develop a non-destructive evaluation (NDE) procedure for evaluating the integrity of rectangular and square reinforced concrete (RC) slabs. This procedure employs both dynamic frequency and deformation response signatures to track changes in the slab following dynamic excitation. Such a procedure could provide a good basis for practising engineers to conduct nondestructive testing (NDT) and evaluation of general RC structures. The response of RC floor slabs to dynamic excitation have been experimentally studied at 1/3rd scale for two aspect ratios (square and rectangular), three concrete grades, and with and without cement replacement under clamped edge conditions. The model slabs were subjected to series of quasi-static loading and unloading sequences, to increasing load levels until failure was reached. At the unloaded part of each load cycle, the slabs were subjected to dynamic excitations, alternately using a hand-held, Bruel and Kjaer (B and K) impact hammer, and broad-band burst chirp shaker excitation. For the larger square slabs, at each unloaded part of the load cycle, a 265 gm steel ball bearing dropped from a fixed, standard height to provide more robust impulse excitation. All of the slabs were instrumented with optimally located accelerometers and strain gauges to capture the slab responses. The acceleration, deflection and strain readings resulting from the dynamic excitation were recorded at incremental load steps, from the initial unloaded state up to failure, and subsequently evaluated and analysed. The results show that the changes resulting from damage are readily observable, in the fundamental and higher modes of vibration and in the load-deflection and strain responses. These changes have been examined and analysed in both the time and frequency domains, and using other techniques, to establish the viability of this approach in evaluating the integrity of RC and other complex structures.

The thermoregulatory responses of subjects wearing two different forms of rugby league jersey, one with plastic sponsorship recognition and numbering (trial Gl) and one without (trial G2), and a lightweight alternative (trial G3), were compared with a trial without any form of upper body garment (trial GO). Ten male volunteers, mean age 20.9 (±2.3) years, height 179.8 (±4.7) cm, weight 80.2 (±8.9) kg, and body surface area 1.99 (±0.13) m2, participated in this study. Subjects had a mean maximal oxygen uptake capacity of 56.0 (±6.3) ml.kg.min-1 and a sum of 8 skinfolds of 80.6 (±23.8) mm. Subjects were exercised at approximately 50% of maximal oxygen uptake in a warm humid environment for 50 minutes. Mean ambient temperature was 27.6°C (±0.32) with a relative humidity of 64.7% (±1.44). Measurements of core and skin (7 sites) temperature, heart rate, oxygen uptake, plasma volume, peak lactate concentration, and pre- and post-trial body weight, hematocrit and garment weight were recorded. The statistical results showed that all subjects experienced significant (p ≤.0001) decreases in body weight representing a percentage decrease ranging from 1.2-1.3%. No significant difference was found between trials with respect to body weight change. No significant effect of garment type was found on pre- and post-trial hematocrit, plasma volume changes or peak blood lactic acid concentration. However, mean peak lactate was highest for trial Gl (5.6 mmol.L-1 ±2.2) and lowest for trial G3 (4.6 mmol.L-1 ±1.27). Post-trial core temperature was significantly (p≤ .0001) higher than the resting value; no significant difference was found between trials. The mean absolute increase for all experimental trials was 0.9°C. A significant (p≤.005) difference between mean total (7 sites) skin temperature was found with a post-hoc test revealing that trials Gl and G2 were significantly higher than trial GO; no significant difference was found when comparing trial G3 with trial GO or when comparing the garments between each other. Mean skin temperature under the garment (4 sites) was found to be significantly (p≤.05) higher for all trials involving a garment when compared with mean skin temperature outside (3 sites) the garment; no significant difference was found between trials. Mean oxygen uptake was significantly different between trials (p≤.005), with trial Gl and G3 found to be significantly lower than trial GO; no difference was found when comparing the garments with each other. Post-trial garment weights were significantly (p≤.001) heavier than pre-trial and were significantly (p≤.0001) different when compared with each other. There was no significant effect on heart rate, haematocrit, plasma volume changes, peak blood lactic acid concentration, or core temperature due to garment type. However, differences in skin temperature suggest that the garment used in trial G3 may have a benefit. Further research should consider the impact of increased exercise intensity and/or environmental temperature and humidity on the measured parameters while wearing the garments described in this study.

PI3Ks (phosphoinositide 3-kinases), a family of enzymes expressed in immune cells, are activated in response to a wide variety of stimuli by generating second lipid messengers. A subset of singnaling molecules containing lipid-binding pleckstrin homology (PH) domains are downstream molecules of PI3K signaling pathway, essential to mediate the functional outcomes of PI3Ks. Bam32 / DAPP1 is a PH domain-containing adaptor protein, which was discovered from human tonsil germinal centers (GCs); however, its biological function related to GCs, where efficient T-cell-dependent (TD) antibody responses are generated, is unknown. This thesis is focused on the effect of genetic or pharmacological blockade of PI3K p110delta activity on T and B cells, and the role of Bam32 in GC responses. Type 2 cytokine responses are significantly decreased in p110delta-inactivated mice, whereas Type 1 cytokine responses are increased or comparable after primary and secondary immunization. Hallmarks of asthma, airway inflammation and respiratory hyper-responsiveness are dramatically reduced in those mice. Adoptive transfer of OVA-primed splenocytes from normal, but not p110delta-inactivated mice could induce airway eosinophilia in naïve, airway-challenged recipient mice. These data demonstrate a novel functional role for p110delta signaling in induction of Type 2 responses in vivo and may offer a new therapeutic target for Th2-mediated airway disease. Paradoxically, serum IgE levels are markedly increased in OVA-immunized p110delta-inactivated mice despite lower level of swich factor IL-4. In vitro studies showed that p110delta is required to restrain IgE class switch recombination in a B-cell intrinsic manner. Blockade of PI3K activity using broad-spectrum PI3K inhibitors PIK-90 and PI-103 generates similar results. In vivo administration of p110delta-selective inhibitor IC87114 into OVA-immunized mice results in selective elevation of antigen-specific IgE production. Disruption of p110delta signaling leads to increased germline transcription at the epsilon locus (epsilon GLT) and increased induction of activation induced cytidine deaminase (AID) enzyme, suggesting deregulation at the level of the isotype switch process. Moreover, p110delta signaling selectively regulates the expression level of transcription factor Bcl6 and IRF4, which may be responsible for the regulation of AID and epsilon GLT. PI3K signaling regulates multiple steps of GC development, and Bam32 may be involved. GCs dissipate prematurely in Bam32-deficient mice after immunization with OVA/alum. In vitro, Bam32-deficient B cells are functional competent in proliferation, chemotaxis, isotype switching and plasma cell differentiation in response to signals present in GCs. In vivo, Bam32-deficient GC B cells proliferate normally; however, they are more apoptotic. Adoptive transfer studies indicated that intrinsic defect of Bam32-/- B cells leads to premature GC dissolution. Additionally, GCs formed by Bam32-/- B cells contain fewer T cells, implying that Bam32 is required for B cell-dependant T cell accumulation within established GCs. Treatment of Bam32-/- mice with agonistic anti-CD40 fully restored GC persistence and IgG1 isotype switching, demonstrating that Bam32-deficient GC B cells are functionally competent when access to cognate signals is not limiting. Collectively, those data demonstrate that Bam32 is not required for GC initiation, but rather functions in a late checkpoint of GC progression associated with T cell recruitment and GC B cell survival. In general, by focusing on PI3K p110delta and its downstream adaptor protein Bam32, my studies clearly indicate that p110delta is a potential therapeutic target for the treatment of Th2-induced airway inflammation. The unexpected immunomodulatory acitivity on IgE switching associated with multiple PI3K inhibitor compounds is first discovered in this thesis, suggesting that more need to be investigated in this aspect before those inhibitor compounds are widely used in the clinic. Furthermore, the specific regulatory role of Bam32 in GCs represents a unique model for us to study the late GC checkpoint in regarding to in vivo GC B cell and T cell interaction, which is an important issue need to be clarified in order to fully understand GC responses.

PI3Ks (phosphoinositide 3-kinases), a family of enzymes expressed in immune cells, are activated in response to a wide variety of stimuli by generating second lipid messengers. A subset of singnaling molecules containing lipid-binding pleckstrin homology (PH) domains are downstream molecules of PI3K signaling pathway, essential to mediate the functional outcomes of PI3Ks. Bam32 / DAPP1 is a PH domain-containing adaptor protein, which was discovered from human tonsil germinal centers (GCs); however, its biological function related to GCs, where efficient T-cell-dependent (TD) antibody responses are generated, is unknown. This thesis is focused on the effect of genetic or pharmacological blockade of PI3K p110delta activity on T and B cells, and the role of Bam32 in GC responses. Type 2 cytokine responses are significantly decreased in p110delta-inactivated mice, whereas Type 1 cytokine responses are increased or comparable after primary and secondary immunization. Hallmarks of asthma, airway inflammation and respiratory hyper-responsiveness are dramatically reduced in those mice. Adoptive transfer of OVA-primed splenocytes from normal, but not p110delta-inactivated mice could induce airway eosinophilia in naïve, airway-challenged recipient mice. These data demonstrate a novel functional role for p110delta signaling in induction of Type 2 responses in vivo and may offer a new therapeutic target for Th2-mediated airway disease. Paradoxically, serum IgE levels are markedly increased in OVA-immunized p110delta-inactivated mice despite lower level of swich factor IL-4. In vitro studies showed that p110delta is required to restrain IgE class switch recombination in a B-cell intrinsic manner. Blockade of PI3K activity using broad-spectrum PI3K inhibitors PIK-90 and PI-103 generates similar results. In vivo administration of p110delta-selective inhibitor IC87114 into OVA-immunized mice results in selective elevation of antigen-specific IgE production. Disruption of p110delta signaling leads to increased germline transcription at the epsilon locus (epsilon GLT) and increased induction of activation induced cytidine deaminase (AID) enzyme, suggesting deregulation at the level of the isotype switch process. Moreover, p110delta signaling selectively regulates the expression level of transcription factor Bcl6 and IRF4, which may be responsible for the regulation of AID and epsilon GLT. PI3K signaling regulates multiple steps of GC development, and Bam32 may be involved. GCs dissipate prematurely in Bam32-deficient mice after immunization with OVA/alum. In vitro, Bam32-deficient B cells are functional competent in proliferation, chemotaxis, isotype switching and plasma cell differentiation in response to signals present in GCs. In vivo, Bam32-deficient GC B cells proliferate normally; however, they are more apoptotic. Adoptive transfer studies indicated that intrinsic defect of Bam32-/- B cells leads to premature GC dissolution. Additionally, GCs formed by Bam32-/- B cells contain fewer T cells, implying that Bam32 is required for B cell-dependant T cell accumulation within established GCs. Treatment of Bam32-/- mice with agonistic anti-CD40 fully restored GC persistence and IgG1 isotype switching, demonstrating that Bam32-deficient GC B cells are functionally competent when access to cognate signals is not limiting. Collectively, those data demonstrate that Bam32 is not required for GC initiation, but rather functions in a late checkpoint of GC progression associated with T cell recruitment and GC B cell survival. In general, by focusing on PI3K p110delta and its downstream adaptor protein Bam32, my studies clearly indicate that p110delta is a potential therapeutic target for the treatment of Th2-induced airway inflammation. The unexpected immunomodulatory acitivity on IgE switching associated with multiple PI3K inhibitor compounds is first discovered in this thesis, suggesting that more need to be investigated in this aspect before those inhibitor compounds are widely used in the clinic. Furthermore, the specific regulatory role of Bam32 in GCs represents a unique model for us to study the late GC checkpoint in regarding to in vivo GC B cell and T cell interaction, which is an important issue need to be clarified in order to fully understand GC responses.

No description available.

Title page, table of contents and abstract only. The complete thesis in print form is available from the University of Adelaide Library. / Visual movement is important to most animals that move quickly, and even some that do not. What neural computations do animals use to see visual motion in their natural environment? The visual stimulus used to perform experiments on such questions is critical, and has historically limited the ability to perform experiments asking critical questions about responses to naturalistic moving scenes. The ability to display, at high frame rates, moving natural panoramas and other stimuli distorted to compensate for projection onto a flat screen was important to the experiments described here. I therefore created a software library called the 'Vision Egg' that allows creation of motion stimuli with recent, inexpensive computer hardware, and was used for the experiments described here. Additionally, I developed a mathematical model to determine the quality of motion simulation possible with computer displays. This model was applied to reach an understanding of the 'ghosting' artifact sometimes perceived on such apparent motion displays. Psychophysical experiments on human observers confirmed model predictions and allowed testing of synthetic motion blur for simulation of smooth motion and elimination of the ghosting artifact. I show this synthetic motion blur is optimal in the sense of creating the closest perception possible to that of smooth motion experienced in natural settings. Experiments on humans and flies show that such synthetic 'motion blur' has no effect on motion detection per se. However, ghosting in sampled displays results in information not present in smooth motion at high velocities, permitting inappropriate discrimination of rapidly moving features. I performed experiments measuring the responses of hoverfly wide-field motion detecting neurons (HS cells) in adapted and unadapted states to the velocity of natural scenes. Responses to natural images of varied intrinsic contrast depend little on the choice of image. Artificially reducing contrast, however, does reduce response magnitudes. Finally, the greatest component of response variation to natural scenes is directly related to local structure in the scenes, and could thus be called 'pattern noise.' The large receptive field of HS cells arises from a (non-linear) spatial summation of numerous elementary motion detectors. I measured spatial and temporal contrast sensitivity of small patches in the large receptive field. As predicted from the presence of a frontal optical acute zone, spatial tuning is highest frontally. A sexually dimorphic 'bright zone' in the frontodorsal eye is correlated with enhanced contrast sensitivity and faster temporal tuning in HS cells with receptive fields in this region of male flies. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1125182 / Thesis (Ph.D.) -- University of Adelaide, School of Molecular and Biomedical Science, 2004

Title page, table of contents and abstract only. The complete thesis in print form is available from the University of Adelaide Library. / Visual movement is important to most animals that move quickly, and even some that do not. What neural computations do animals use to see visual motion in their natural environment? The visual stimulus used to perform experiments on such questions is critical, and has historically limited the ability to perform experiments asking critical questions about responses to naturalistic moving scenes. The ability to display, at high frame rates, moving natural panoramas and other stimuli distorted to compensate for projection onto a flat screen was important to the experiments described here. I therefore created a software library called the 'Vision Egg' that allows creation of motion stimuli with recent, inexpensive computer hardware, and was used for the experiments described here. Additionally, I developed a mathematical model to determine the quality of motion simulation possible with computer displays. This model was applied to reach an understanding of the 'ghosting' artifact sometimes perceived on such apparent motion displays. Psychophysical experiments on human observers confirmed model predictions and allowed testing of synthetic motion blur for simulation of smooth motion and elimination of the ghosting artifact. I show this synthetic motion blur is optimal in the sense of creating the closest perception possible to that of smooth motion experienced in natural settings. Experiments on humans and flies show that such synthetic 'motion blur' has no effect on motion detection per se. However, ghosting in sampled displays results in information not present in smooth motion at high velocities, permitting inappropriate discrimination of rapidly moving features. I performed experiments measuring the responses of hoverfly wide-field motion detecting neurons (HS cells) in adapted and unadapted states to the velocity of natural scenes. Responses to natural images of varied intrinsic contrast depend little on the choice of image. Artificially reducing contrast, however, does reduce response magnitudes. Finally, the greatest component of response variation to natural scenes is directly related to local structure in the scenes, and could thus be called 'pattern noise.' The large receptive field of HS cells arises from a (non-linear) spatial summation of numerous elementary motion detectors. I measured spatial and temporal contrast sensitivity of small patches in the large receptive field. As predicted from the presence of a frontal optical acute zone, spatial tuning is highest frontally. A sexually dimorphic 'bright zone' in the frontodorsal eye is correlated with enhanced contrast sensitivity and faster temporal tuning in HS cells with receptive fields in this region of male flies. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1125182 / Thesis (Ph.D.) -- University of Adelaide, School of Molecular and Biomedical Science, 2004