The control of skeletal muscle relies on a complex integration between descending central input and information that originates from receptors that lie within peripheral tissue. The following investigations were performed to contribute to our understanding of this control. Study 1 ( Chapter 2 ) was designed to determine ( using the H - reflex ) if muscle spindle feedback is similar in the gastrocnemius and soleus. The strength of the H - reflex at rest and during contraction was compared between muscles. The results showed that the maximal H - reflex obtained at any level of contraction is larger in the soleus than in the gastrocnemius. We argue that along with the muscles having different structures and functions, the recruitment capabilities of their motoneurons are quite different. We also found that the maximal M - wave, which has for years been thought to be a consistent measure of maximal muscle activity, was quite variable within subjects during different conditions. Review of the maximal M - wave literature showed evidence that variability in this response did exist between conditions, but that the variability was rarely seen in pooled data, and was therefore not often reported. Study 2 ( Chapter 3 ) was developed to determine if experimental recording techniques, or analysis methods, could affect the magnitude of the maximal M - wave within subjects. The first finding of this study showed that the two most commonly used analysis methods ( peak - to - peak amplitude and area ) provided comparable results, and could not account for the differences seen in the maximal M - wave magnitude. The study did however suggest that the orientation of surface recording electrodes can significantly alter the recorded signal. We argue that although bipolar surface recording is considered superior to monopolar recording in its ability to record a clean signal, it has a large limiting factor, which we call " signal cancellation ". The third study ( Chapter 4 ) focused on the variability in M - wave strength in the gastrocnemius and soleus during a variety of ankle orientations and voluntary contraction levels. This study supported our previous work, and showed that when monopolar recording is used, consistent and significant differences exist in the strength on the M - wave obtained during different conditions that were not seen in bipolar recordings. It was concluded that the difference in maximal M - wave strength obtained during different muscle conditions may be related to a change in the recording electrode to muscle bulk relationship. This finding is important as M - wave strength is consistently used as a normalisation factor in reflex studies, and therefore variability in this measure may seriously affect the results obtained during muscle reflex investigations. The final study ( chapter 5 ) considered the size of the H - reflex, the level of background muscle activity, and the subjects ' weight distribution, during painful and non - painful conditions. We determined that these factors were not modified by pain induced in either agonist or antagonist muscles. The final chapter outlines the major findings from this work, highlights limitations to the research conducted using the H - reflex, and makes suggestions for future research in this area. / Thesis (Ph.D.)--School of Molecular and Biomedical Science, 2006.

Purpose: The purpose of this study was to determine if there were any differences between four different target types when measuring the near point of convergence in adults. Methods and Material: The near point of convergence was measured in 35 subjects with a visual acuity of at least 1.0 (6/6) in each eye and without any strabismus. The targets used were: the tip of a pen, an accommodative target, the RAF line target and a penlight viewed through red-green filters. Both break and recovery points were assessed for the different techniques. Each target was used twice in consecutive order. The line target from RAF ruler was copied on to a small plastic ruler in order to be able to use the same ruler for measuring the results. All subjects were fitted with their best correction in the trial frame after a complete refraction. The measurements were taken to the nearest 0.25cm. Results: There was no difference found between NPC break values for the different target types in the control group. The NPC values were found to be 5.0/7.4 in the control group and 10.8/18.2 in the anomalous group. The accommodative target was found to give more remote values (11.5cm) than expected in comparison to the other targets in the anomalous group. Conclusion: In patients with normal NPC, the measurements can be taken with line target or Acc. target. Patients with receded NPC values should be evaluated with penlight and red-green glasses or at least twice with the tip of a pen.

There is a growing demand for faster, improved data and voice services in rural areas without modern telecom infrastructure. A wireless network is often the only feasible solution for providing network access in this environment, due to the sparse populations and difficult natural conditions. A system solution that incorporates the Multipoint Communication System (MCS) algorithm created by TRLabs into the available IEEE 802.11b Wireless Local Area Network (WLAN) devices was proposed and studied in this thesis. It combines the advantages of both systems, that is, the MCS capability of integrating Voice over Internet Protocol (VoIP) and data services and the IEEE 802.11b standard, currently the most widely used in WLAN products. A system test bed was set up inside Network Simulator-2 (NS-2). The data and VoIP performance was tested. Modifications to the original MCS algorithm to improve system performance were made throughout this thesis. In a constant rate radio channel, data performance (throughput and transmission efficiency) was measured using the original MCS algorithm, which was comparable to the standard Distribution Coordination Function (DCF) operation of IEEE 802.11b when both were simulated at similar conditions. On an 802.11b platform, the Automatic Rate Fallback (ARF) feature was incorporated into the original MCS algorithm. However, when clients with different data rates were present in the same channel, all the clients involved received unacceptably low and equal data throughput, dragged down by the low rate clients. A modified MCS data polling algorithm was proposed with the capability of repeated polling, which eliminated the negative effect of low rate clients in a multi-rate channel. In addition, the original MCS algorithm was modified to be more efficient in the voice polling process. The voice performance and data throughput were tested at various conditions. However, the one-by-one polling still resulted in very low voice transmission efficiency. The time wasted became more severe with increasing relay distance and channel rate (only 8.5% in an 11 Mbps channel at 30 km). A new voice handling process similar to Time Division Multiple Access (TDMA) mode was implemented and simulated. Its voice efficiency can be kept at 25% at any setting of relay distance and channel rate. Data transmission in the same channel can also benefit from using the new voice scheme. The normalized saturation throughput could be improved by 13.5% if there were 40 voice clients involved in an 11 Mbps channel at the relay distance of 15 km, compared to the original MCS algorithm. More improvement in voice efficiency, voice capacity, and data throughput can be achieved at longer relay distance, or with more voice calls set up.

There is a growing demand for faster, improved data and voice services in rural areas without modern telecom infrastructure. A wireless network is often the only feasible solution for providing network access in this environment, due to the sparse populations and difficult natural conditions. A system solution that incorporates the Multipoint Communication System (MCS) algorithm created by TRLabs into the available IEEE 802.11b Wireless Local Area Network (WLAN) devices was proposed and studied in this thesis. It combines the advantages of both systems, that is, the MCS capability of integrating Voice over Internet Protocol (VoIP) and data services and the IEEE 802.11b standard, currently the most widely used in WLAN products. A system test bed was set up inside Network Simulator-2 (NS-2). The data and VoIP performance was tested. Modifications to the original MCS algorithm to improve system performance were made throughout this thesis. In a constant rate radio channel, data performance (throughput and transmission efficiency) was measured using the original MCS algorithm, which was comparable to the standard Distribution Coordination Function (DCF) operation of IEEE 802.11b when both were simulated at similar conditions. On an 802.11b platform, the Automatic Rate Fallback (ARF) feature was incorporated into the original MCS algorithm. However, when clients with different data rates were present in the same channel, all the clients involved received unacceptably low and equal data throughput, dragged down by the low rate clients. A modified MCS data polling algorithm was proposed with the capability of repeated polling, which eliminated the negative effect of low rate clients in a multi-rate channel. In addition, the original MCS algorithm was modified to be more efficient in the voice polling process. The voice performance and data throughput were tested at various conditions. However, the one-by-one polling still resulted in very low voice transmission efficiency. The time wasted became more severe with increasing relay distance and channel rate (only 8.5% in an 11 Mbps channel at 30 km). A new voice handling process similar to Time Division Multiple Access (TDMA) mode was implemented and simulated. Its voice efficiency can be kept at 25% at any setting of relay distance and channel rate. Data transmission in the same channel can also benefit from using the new voice scheme. The normalized saturation throughput could be improved by 13.5% if there were 40 voice clients involved in an 11 Mbps channel at the relay distance of 15 km, compared to the original MCS algorithm. More improvement in voice efficiency, voice capacity, and data throughput can be achieved at longer relay distance, or with more voice calls set up.

Acoustic point-source reflection from an unperturbed seabed with a continuously varying density and sound speed profile in a fluid-like sediment layer overlying an elastic basement is considered in this paper. This fundamental problem has illuminated many interesting phenomena about the effects of sediment stratification on acoustic wave interactions with the seabeds. The analysis employs the analytical solutions for the Helmholtz equation in the sediment layer, in which the density and the sound speed are, respectively, described by three kinds of geological models. The results have demonstrated that the effects of sediment stratifacation are confined in a region in range, where the reflection field is dominated by the reflected ray bundles containing ray components with the grazing angles which are neither too steep nor too shallow. The effects of many other factors, such as frequency, sediment thickness, basement elasticity, on the reflection fields are investigated, in particular, the interface wave component may become important in the region close to the seabed, if the sediment thickness is relatively thin in comparison with the acoustic wave length.

Reservoir simulation models are becoming increasingly sophisticated in tandem with the rapid development of geological modeling methods. Widely used commercial simulators usually model flow through heavily faulted and structurally complex geometries with the flexibility provided by corner-point geometry. However, the nonorthogonality component present within these frameworks may compromise the solution accuracy of the model and the subsequent operational decisions involved. We propose a systematic methodology to evaluate the impact of complex gridding introducing a new streamline formulation for corner-point geometry. Based on a new time-like variable, the new formulation provides a significantly simpler and more robust development to handle the complexity in structurally demanding and faulted systems. It retains the simplicity and speed of streamline-based flow models and provides an efficient way to visualize nonorthogonal effects. Applied to various geometries showing challenging features of geology and flow, the displacement fronts obtained from streamline-derived analytic calculation identified the discrepancies characteristic between known solutions and results from two widely used commercial simulators.

Reproduction de : Thèse de doctorat : Linguistique : Metz : 1996. / Titre provenant de l'écran-titre. Notes bibliographiques. Index.

In this dissertation, three types of paper-based analytical devices for point-of-care biosensing, a potentiometric method for analyzing percent hemoglobin A1c (%HbA1c) and a PDMS-glass microelectrochemical device for highly reproducible amperometric measurement in microdroplet, are described. The first paper-based sensing device is fabricated using the principles of origami (paper folding). The three-dimensional origami paper analytical device (oPAD) is fabricated on a single sheet of flat paper in a single photolithographic step and assembled by simply folding the paper by hand. Following analysis, the device can be unfolded to reveal each layer for optical and fluorescent read-out. The second type of paper-based device has an integral aluminum/air battery as the power source and reports its output using Prussian blue as an electrochromic indicator. The integrated aluminum/air battery powers both the electrochemical sensor and the electrochromic read-out. The applicability of the device to point-of-care sensing is demonstrated by qualitative detection of glucose and H2O2 in artificial urine. The third type of paper-based device (oPAD 2) uses an aptamer to recognize the analyte, adenosine, a glucose oxidase tag to modify the relative concentrations of an electroactive redox couple, and a digital multimeter to transduce the result of the assay. Adenosine is quantitatively determined using this device with a detection limit of 11.8 uM. The method for measuring HbA1c concentration, hemoglobin concentration, and thus %HbA1c in human blood is based on potentiometry. We use Alizarin red s (ARS) as a redox indicator. The potential shift of ARS owing to diol-boronic acid complexation is used to determine the HbA1c, which is a competitor of ARS for the complexation reaction. The concentration of Hb is determined by reacting it with Fe(CN)₆³⁻ and measuring the potential shift arising from the reduction of Fe(CN)₆³⁻ by Hb. The results obtained for %HBA1c in human blood are in good agreement with those determined using a reference method. The method for highly reproducible chronoamperometric analysis of the contents of microdroplets is developed. Aqueous microdroplets (~ 1 nL) and separated by a fluorocarbon solvent are generated within a microfluidic device using a T-shaped junction. Highly reproducible quasi-steady-state currents (relative standard deviations = ~ 2%) are observed when the microdroplets are stretched by a factor of 10 in a narrowed segment of a microchannel, which leads to desirable intradroplet mass transfer characteristics. Importantly, the design of the microelectrochemical device ensures direct contact between intradroplet redox molecules and the electrode surface to study inner-sphere electrocatalytic processes such as the oxygen reduction reaction. Finite-element simulations are presented that are in accord with the experimental findings. / text

Obesity related employer healthcare costs increased 8% from 2010 to 2011 (PwC, 2012; Durden, 2008), which has spurred an increase in worksite weight management programs. Due to minimal success of individually focused programs (Anderson, 2009; Mhurchu, 2010), efforts have shifted to the potential impact of environmental interventions. The purpose of this study was to evaluate the influence of a red, yellow, and green (R/Y/G) point of purchase (POP) labeling system on perceived health literacy and purchasing behaviors at three on-campus eateries frequented by university faculty and staff. Foods were rated as red, yellow, or green based on the Nutrient Rich Food Index. All foods were labeled with stickers that looked like miniature traffic lights with the appropriate color light lit up through menu boards and nametags. Posters, emails and table tents were also used to communicate about the intervention. In order to provide various levels of exposure, the first eatery had the intervention for six weeks, the second for four weeks, and the last for two weeks. Eatery patrons (N=191 across the three locations) completed a paper and pencil pre-intervention survey assessing healthy eating intentions, knowledge, and behaviors. Post-intervention data collection was conducted via online survey (N=89), and consisted of the pre-test items and additional questions about label awareness and utilization. While the intervention did not appear to influence healthy eating intentions or knowledge, 41.6% of the patrons reported that the labels influenced their food choices. Patrons also reported being aware of, understanding, and using the labels. The average food sales for the six weeks prior to the intervention were compared to the average food sales during the intervention. Food sales data were compared by location and food category (R/Y/G). There was a significant increase in green food sales and a significant decrease in red food sales (r=-.375, p=.044). However, there were no significant differences between locations. These findings suggest that future research with the traffic light labeling is warranted. / text

The Spruce Point Site (DjKq-1) in the northwestern sector of Lake of the Woods, Ontario, is a Selkirk site dated through ceramic seriational analysis to the sixteenth or seventeenth century A.D. It is rare for two reasons. First, it is a single component among a plethora of multi-component sites with collapsed stratigraphy which characterize the major portion of the Lake of the Woods prehistoric record. This factor allows for the first analysis and description of Lake of the Woods Selkirk community patterns, material remains, especially ceramics, and adaptive strategy free from stratigraphic interference. The assemblage is represented by ceramics and lithics akin to the Winnipeg River Complex and a faunal sample indicating an exploitation pattern using an unspecialized strategy and varied resources. Second, the site has remains of two house structures, unreported elsewhere for the Selkirk Composite, that are similar in floor plan and size to earlier Laurel structures and later Cree houses reported in the ethnographic literature. House style and geographic location, plus the faunal assemblage indicate the site was occupied during the summer and was chosen for its varied animal, plant and lithic resources.