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The large conductance calcium dependent potassium (BKCa) channels are expressed in a large variety of cell types including neurons where they modulate excitability and action potential shape. Within the enteric nervous system, stretch-sensitive BKCa channels are expressed on intrinsic primary afferent neurons (IPANs) where they decrease the neurons’ excitability during intestinal contractions. A major determinant of peristalsis is slow excitatory neurotransmission (sEPSPs) within the IPAN to IPAN sensory network, and we wondered whether such transmission might also alter BKCa channel opening. All experiments were performed on longitudinal-muscle myenteric preparations prepared from jejunal segment taken from freshly euthanized adult male Swiss Webster mice. With the myenteric plexus exposed by microdissection, BKCa channel activity was recorded in cell-attached mode via the patch clamp technique. BKCa channel activity was recorded before and after presynaptic electrical stimulation, which was designed to evoke postsynaptic sEPSPs. The morphotype was verified by intracellular injection of a marker dye (neurobiotin). In addition, a blocker and opener were used to identify the effects of BKCa currents on IPAN properties. Analysis of unitary channel recordings revealed increased BKCa open probability (NPo) at fixed trans-patch potentials following sEPSPs. All BKCa channels were independently voltage sensitive with increased NPo during patch depolarisation. Analysis of whole-cell experiments also revealed BKCa channels have a significant effect on the undershoot amplitude of action potentials, and the rate at which IPANs repolarise. This study demonstrates that sEPSPs within the enteric nervous system modulate the function of BKCa channels in IPANs adding to the mechanistic understanding of enteric synaptic transmission and providing a potential target for therapeutic modulation of enteric nervous system excitability. / Thesis / Master of Science (MSc)

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This dissertation details the development of the star spiral antenna and demonstrates the advantages of the star spiral when used in a wideband array with variable element sizes. The wideband array with variable element sizes (WAVES) is a multi-octave array that uses different sized circular Archimedean spirals for each octave of frequency coverage. A two-octave WAVES array has been presented in the literature, but a gap in the two-octave frequency coverage exists along the principal axes. The star spiral antenna was developed to eliminate the performance gap in the WAVES array. The star spiral is a type of slow-wave spiral that also offers array-packing advantages, particularly for the WAVES array. The size reduction that can be achieved with the star spiral is comparable to that of the square spiral, but the star spiral is much more efficient in terms of its expected size reduction compared to its circumference. The far-field patterns, gain, and scan performance of the star spiral are similar to that of the circular Archimedean spiral. The use of the star spiral to eliminate the performance gap in a WAVES array of circular Archimedean spirals is detailed. Furthermore, a three-octave WAVES array of star spirals is built and measured, and the scan performance of the array is investigated via simulation. / Ph. D.

Eighteen untrained males [age: 23 +/- 0.6 yr (SEM)] were randomized into high intensity (HIT: above lactate threshold, LT), moderate intensity (LIT: below the LT) or no training (NT) groups. Subjects trained on a cycle ergometer 4 days.wk-1 for 6 wk with the power output held constant. Maximal cycle ergometry was performed before and after the training period to determine changes in power output and oxygen consumption (VO2) at the LT and peak exertion. Before training and after 1, 2, 4, and 6 wk, subjects performed high constant-load (HCL) cycling bouts to quantify training adaptations in the SC. Training was designed to keep total work equivalent between the HIT and LIT groups. Increases in power output and VO2 at LT and peak exercise after 6 wk were noted in the HIT and LIT groups in comparison to NT group (p<0.05). No differences were noted between HIT and LIT. Two-way repeated measures ANOVA revealed a significant trial*group interaction for adaptation in the SC (p<0.001). After 1wk of training, a significant reduction in the SC was noted for HIT [mean+/-SEM]: (pre-training (PT): 703 +/- 61 ml.min-1; 1 wk: 396 +/- 60 ml.min-1) (- 44% from PT). Further adaptation for the HIT was also noted at 4 wk: 202 +/- 45 ml.min-1 (-71% from PT). For LIT, a significant reduction was noted at 2 wk (PT: 588+/-76 ml.min-1; 2 wk: 374 +/- 50ml.min-1) (-36% from PT). Further adaptation for LIT group was noted at 6 wk (252 +/- 38 ml.min-1) (- 57% from PT). Adaptation in SC was not noted at any interval for NT. Temporal changes in blood lactate (r = 0.40) and ventilation (r = 0.72) were significantly correlated with the changes for SC over the 6 wk training period (p<0.05). In conclusion, it was demonstrated that training at supra-LT and sub-LT intensities produces similar improvement in VO2 and power output at peak exercise and in the LT, when total work output is controlled. However, training at supra-LT intensity promotes larger and faster adaptations in the SC than training at the sub-LT levels. / Ph. D.

Esta tesis doctoral tiene como objetivo el diseño y la implementación de dispositivos ópticos novedosos capaces de realizar tareas de procesado de señales de rediofrecuencia, concretamente en las bandas de microondas y milimétricas, explotando para ello efectos de luz lenta que tienen lugar sobre algunos medios físicos que presentan características especiales. Con este propósito, se han investigado estructuras basadas en tecnología de semiconductor en guiaonda, además de estructuras de naturaleza resonante sobre circuitos en silicio y compuestos híbridos fabricados con materiales activos pertenecientes a los grupos III-V sobre silicio. En concreto, se han prouestos diferentes circuitos ópticos capaces de desarrollar tareas propias de desfasador y retardadeo verdadero de banda ancha para señales de radiofrecuncia. El comportamiento de dichos circuitos ópticos bajo estudio se ha caracterizado mediante modelado teórico, quedando éstos adecuadamente validados a través de resultados experimentales. En primer lugar, se han llevado a cabo estudios concernientes a la degradación producida por ruido en estructuras desfasadores formadas por amplificadores ópticos de semiconductor. Como resultado, se ha propuesto una nueva estructura que ha revertido en un rendimiento optimizado en términos de ruido sin que ello suponga una alteración en su funcionnalidad básica como desfasador. Esta estructura desfasadora ha sido el elemento clave en el ensamblado de un filtro elimina banda sintonizable. En segundo lugar, se han utilizado diferentes configuraciones basadas en anillos de silicio con dimensiones micrométricas para el desarrollo e implementación de diferentes procesadores de señal, tales como filtros reconfigurables y sintonizables y retardadores multicanal. Concretamente, se ha introducido un nuevo concepto inspirado en la técnica conocida como SCT, cuyo beneficio redunda en un aumento considerable del ancho de banda útil de las señales de radiofrecuencia a procesar gracias a / Lloret Soler, JA. (2012). Slow Light Effects in Photonic Integrated Circuits with Application to Microwave Photonics [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/16472

Literature on reading comprehension assessment advocates a multiple-measures approach over a single-test methodology in view of the cognitive and linguistic complexity of the behavior being evaluated. Relationships among multiple measures have been observed, but no study has examined the nature of relationships among categories of comprehension assessment (product-process) or has conducted an explicit test of possible patterns of association, expressed as three models of comprehension assessment, in a sample of learning disabled subjects. Therefore, the passage comprehension of 48 seventh and eighth grade males was assessed by questioning, retelling, cloze and miscue assessments followed by a correlational analysis of scores. Regression analysis examined which of the four assessments best predicted subjects' scores on a standardized test. The data did not confirm any of the three hypothesized models of comprehension assessment but subjects' comprehension appeared to be partly a function of how it was measured. Performance on the miscue assessment best predicted standardized test performance. / Ed. D.