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Non-steroidal anti-inflammatory drugs (NSAIDs) have been shown to suppress bone formation when administered before, but not if administered after, an acute bout of mechanical load in rats. The NSAID ibuprofen inhibits cyclooxygenase-2 enzyme, effectively reducing loading induced prostaglandin E2. Whether this affects eventual bone mass gains after multiple sessions of a more physiological mechanical loading regimen is unclear. Therefore, the aim of this study was to test the hypothesis that gains in bone mass and size will be diminished in adult rats given ibuprofen before, but not after, each exercise bout during 20 days of simulated resistance training (SRT). Virgin female Sprague-Dawley rats (5-mo-old, n=29) completed 9 SRT sessions using stimulated muscle contractions under anesthesia at 75% peak isometric strength on alternate days; each of 20 contractions included 1 sec isometric + 1 sec eccentric contraction. Animals were blocked assigned by body weight to one of three groups: 1) ibuprofen (30mg/kg) before exercise, placebo after (I:P)(n=9), 2) placebo before, ibuprofen after (P:I)(n=10) and 3) placebo before and after (P:P)(n=10). In vivo pQCT scans measured changes in total volumetric bone mineral density (vBMD) and total bone mineral content (BMC) at the proximal tibia (cancellous), and total vBMD, total BMC and total area at midshaft tibia on days -7 and 21. Dynamic histomorphometry on both midshaft tibiae (exercised and non-exercised legs) determined mineralizing surface (MS/BS), mineral apposition rate (MAR) and bone formation rate (BFR) on the periosteal surface. There were no differences in body weights among groups at baseline or at day 21. There were significant gains due to SRT, but not ibuprofen treatment in total BMC (+10.50 ± S.D. +8.15%) and total vBMD (+5.29 ± 3.41%) at the proximal tibia. The midshaft tibia exhibited significant gains in total vBMD (6.68 ± 3.03%), total BMC (19.18 ± 5.51%) and total area (11.68 ± 5.49%) due solely to SRT. Furthermore, there were significant increases in periosteal BFR (pre 21.89 µm3/µm2/d ±2.63; post 717.81 µm3/µm2/d ±100.57) at the midshaft tibia in the exercised vs. non-exercised legs in all groups but no effect of ibuprofen regimen was detected on these indices of bone formation. In the context of robust increase in BFR and bone mass within this simulated resistance protocol, we were unable to detect any impact of ibuprofen administration on the response to bone loading.

In modular hip implants, micro-motion, which leads to fretting corrosion at the head/neck and neck/stem interfaces, has been identified as a major cause of early revision in hip implants, particularly those with heads larger than 32mm. It has been found that the type of fluid used to simulate the fretting corrosion of biomedical materials is crucial for the reliability of laboratory tests. Therefore, to properly understand and effectively design against fretting corrosion damage in modular hips, there is the need to replicate the human body environment as closely as possible during in-vitro testing and validation. In this work, corrosion behavior of CoCrMo in 0.14 M NaCl, phosphate buffered saline (PBS) and clinically relevant simulated body fluid (sbf) is carried out. Also, fretting corrosion studies of the CoCrMo alloy in a clinically relevant novel simulated body fluid (sbf) environment is studied. The presence of phosphate ions in PBS accounted for the higher corrosion rate when compared with 0.14 M NaCl and sbf environment. Despite the low and comparable corrosion rates in 0.14 M NaCl and sbf, the nature of the protective passive film formed in sbf shows the suitability of the novel sbf for future corrosion and fretting corrosion analysis. Finally, the influence of micro-motion at the modular head/neck and neck/stem interfaces on the concentration of metallic ions that goes into the synovial fluid and surrounding tissues is reported.

The first purpose of this study was to determine the effect of simulation in high school United States History classes on students’ cognitive retention of facts, concepts, and principles. The second purpose was to determine the effect of the simulation technique on students’ and teachers’ affective perceptions of the learning experience.

In this thesis, we consider joint beamforming, power, and channel allocation in a multi-user and multi-channel underlay cognitive radio network (CRN). In this system, beamforming is implemented at each SU-TX to minimize the co-channel interference. The formulated joint optimization problem is a non-convex, mixed integer nonlinear programming (MINLP) problem. We propose a solution which consists of two stages. At first, given a channel allocation, a feasible solutions for power and beamforming vectors are derived by converting the problem into a convex form with an introduced optimal auxiliary variable and semidefinite relaxation (SDR) approach. Next, two explicit searching algorithms, i.e., genetic algorithm (GA) and simulated annealing (SA)-based algorithm are proposed to determine optimal channel allocations. Simulation results show that beamforming, power and channel allocation with SA (BPCA-SA) algorithm achieves a close optimal sum-rate with a lower computational complexity compared with beamforming, power and channel allocation with GA (BPCA-GA) algorithm. Furthermore, our proposed allocation scheme shows significant improvement than zero-forcing beamforming (ZFBF).

There is significant interest in the synthesis of discrete-state random fields, particularly those possessing structure over a wide range of scales. However, given a model on some finest, pixellated scale, it is computationally very difficult to synthesize both large and small-scale structures, motivating research into hierarchical methods. This thesis proposes a frozen-state approach to hierarchical modelling, in which simulated annealing is performed on each scale, constrained by the state estimates at the parent scale. The approach leads significant advantages in both modelling flexibility and computational complexity. In particular, a complex structure can be realized with very simple, local, scale-dependent models, and by constraining the domain to be annealed at finer scales to only the uncertain portions of coarser scales, the approach leads to huge improvements in computational complexity. Results are shown for synthesis problems in porous media.

Live high - train low altitude camps can enhance endurance power at sea level by 1-2% (Levine & Stray-Gunderson, 1997). More convenient methods to simulate altitude exposure are now available, but their effects on performance are less well characterized. In this study, we investigated intermittent hypoxic training (IHT) using an Hypoxicator, a device that produces oxygen-depleted air that athletes breathe intermittently through masks in a small group at a central venue. Twelve highly-competitive, male cyclists and multi-sport athletes (IHT group) underwent IHT in two, four-week bouts separated by eight weeks. Bout one consisted of 20 one-hour exposures and bout two 18 exposures where normal and low-oxygenated air was breathed in alternating five-minute intervals. The percentage of oxygen inhaled by the subjects was adjusted to produce an oxygen saturation of the blood of 88-92% in the first week of the study, decreasing to 76-80% (equivalent to an altitude of approximately 6000m) in the final week. A control group of 13 similar athletes did not use the Hypoxicator. Performance trials and blood tests were at four-week intervals; there were 3 trials (familiarization and reliability) before use of the Hypoxicator, 3 trials after to determine the effect of simulated altitude, then a second four-week exposure and one more trial. The measures of performance were mean power in a 16-km time trial on a Kingcycle ergometer (IHT group only) and power in a lactate-threshold test at 3 mmol/L above baseline (both groups). The measures from the blood tests were haemoglobin and haematocrit. There was a gradual but erratic improvement in performance in the time trial and lactate threshold tests over the course of the study in both groups, indicating an improvement through training. Relative to the last baseline test (Trial 3), the IHT group showed a 0.6% decrease in mean power over and above the effect of training in the 16-km time trial in Trial 4, nine days after last use of IHT. There was a 0.3% increase in mean power independent of the training effect in Trial 7, after the second round of altitude exposure. Uncertainty in these changes in performance was ±3.5% (95% confidence interval). The changes in lactate threshold in trials 4 and 7 indicate a possible improvement as a result of IHT exposure. Uncertainty in these changes was ±4.0%. There were negligible changes in the haemoglobin and hematocrit of either group at any time. There was small evidence of high responders, who were probably subjects with the DD genotype for the angiotensin converting enzyme gene. The time exposed to IHT had no bearing on performance and there was no evidence "peak" in results at either four or eight weeks after exposure to IHT. In summary, four weeks of IHT exposure probably resulted in a trivial effect on 16-km time-trial performance and the effort-independent measures provided no further clear-cut evidence of a performance improvement.

Thesis (Ph.D.)--Duquesne University, 2007. / Title from document title page. Abstract included in electronic submission form. Includes bibliographical references (p. 97-103) and index.

Techn. University, Diss., 2006--Darmstadt.

Thesis (Ph.D.)--University of Tulsa, 1993. / Includes bibliographical references (leaves 240-250).