Walking biomechanics of end stage knee OA and TKA patients.

Osteoarthritis (OA) of the knee is associated with decline in functional capacity and ultimately leads to Total Knee Arthroplasty (TKA) in many of these patients. Exercise regimens prior to surgery may potentially enhance pre and post TKA functional performance. However, assessment of such performance should involve biomechanical factors that characterize the mechanisms with which tasks are performed, and not just the quantity of task performed. The present overall study investigated walking biomechanics of end stage knee OA and TKA patients. Throughout the three sub-studies that comprised the overall investigation, particular emphasis was placed on heelstrike and the loading response phase of gait, in addition to functional ability parameters. The first sub-study investigated gait biomechanics and fatigue during a 6 minute walk for patients with end stage knee OA. Results demonstrated that even if patients were able to maintain their gait velocity throughout the walk, subtle but statistically significant differences at the ankle were present after the 6 minute walk. Knee OA patients may be experiencing higher loading conditions at the knee after 6 min. In order to adapt to fatigue, knee OA patients appear to adopt ankle strategies alleviating the load from a painful knee, rather than knee strategies, causing greater instability and reduced performances. A single walking trial for gait analysis may be insufficient to assess gait compensations due to fatigue in daily activities. In light of the initial results on end stage knee OA walking biomechanics, the second sub-study included investigation of the effects of a 4 to 6 weeks exercise program on TKA outcomes. Results demonstrated that exercise therapy was effective at improving function and reducing pain to a certain extent pre-surgery. However, assessment of the walking biomechanics raised the question of whether improving physical ability improved knee OA condition or caused further knee joint degeneration and possibly the onset of OA in the opposite leg. Control patients exhibited a more careful gait pattern with lower speed and gait parameters reflecting potentially lower impact at heelstrike which may be more beneficial for knee OA conditions. The exercisers\u27 walking characteristics showed evidence of an overstriding gait pattern with potentially reduced shock absorption mechanisms that can lead to lower leg injuries. The third sub-study investigated walking biomechanics of prehab and non prehab subjects one month after surgery and results suggested that the effects of the pre-surgery exercise program did not remain post-surgery. Even if patients in the exercise group had increased physical ability performances and experienced less pain just prior to surgery compared to the control group, one month after surgery there was no difference between the groups. The lack of a significant effect of the exercise program on gait changes post surgery may indicate that the exercise regimen prior to surgery requires an additional component such as gait retraining. Adding a gait retraining component to the prehab protocol may improve the rate of recovery and help patients to maintain the prehab benefits even post TKA surgery

AGRICULTURAL OUTPUT AND PRODUCTIVITY IN THE FORMER SOVIET REPUBLICS

The paper reviews agricultural development in the fifteen former Soviet republics over the period 1965-1998. Production functions are estimated and productivity differences and changes calculated. Large differences were found in terms of productivity and growth between the republics. The differences grew after 1990 reflecting variation in reform policies.Productivity Analysis,

AGRICULTURAL OUTPUT AND PRODUCTIVITY IN THE FORMER SOVIET REPUBLIC

The paper reviews agricultural development in the fifteen former Soviet republics over the period 1965-1997. Production functions are estimated and productivity differences and changes calculated. Large differences were found in terms of productivity and growth between the republics. The differences grew after 1990 reflecting variation in reform policies.International Development, Productivity Analysis,

Haldun Taner'i yasaklamak...

Taha Toros Arşivi, Dosya No: 34-Haldun Taner. Not: Gazetenin "Arada Bir" köşesinde yayımlanmıştır

Sustainable performance : a comparison between the sports, corporate and arts industries

This study sought to recognise individual sustainability as a tangible and identifiable concept, by beginning to determine some of the contributing factors of individual sustainability of performance, or individual sustainability of competitive advantage. As no comprehensive research presently exists in relation to individual sustainability, the approach taken was to build on and extend current research, as well as addressing issues on individual sustainability of performance. An accepted theoretical framework (the resource based theory) was used to guide data collection, and both elite sustainable and elite non-sustainable performers participated. The primary focus of the research was to identify the processes, (individual and historical variables), that were characteristics of sustained performers at an elite level. So that this could be accomplished, a number of aims were proposed, including: To determine the relationship between sustained performance, levels of sustained performance and specific individual and historical variables; to identify whether differences exist as a function of gender; and to identify whether differences exist due to type of performance discipline. A multi-method approach was used, with 50 individuals completing a questionnaire, and 18 individuals participating further in an interview. Results indicated significant differences between sustainable and non-sustainable performers on a variety of variables. For example, sustainable performers demonstrated a significantly higher level of innate confidence as compared to non-sustainable performers. The concept of failure was also highlighted as being of singular importance. Criticality of gender, both generally, and in relation to sustainability was established, with differences also being revealed between industries. Specific variables such as gender, confidence and failure were found to be predictors of sustainability. The findings clearly indicated areas for future consideration in the research and development of the concept of individual sustainability

A cost-benefit analysis of a pellet boiler with electrostatic precipitator versus conventional biomass technology: A case study of an institutional boiler in Syracuse, New York

BACKGROUND: Biomass facilities have received increasing attention as a strategy to increase the use of renewable fuels and decrease greenhouse gas emissions from the electric generation and heating sectors, but these facilities can potentially increase local air pollution and associated health effects. Comparing the economic costs and public health benefits of alternative biomass fuel, heating technology, and pollution control technology options provides decision-makers with the necessary information to make optimal choices in a given location. METHODS: For a case study of a combined heat and power biomass facility in Syracuse, New York, we used stack testing to estimate emissions of fine particulate matter (PM2.5) for both the deployed technology (staged combustion pellet boiler with an electrostatic precipitator) and a conventional alternative (wood chip stoker boiler with a multicyclone). We used the atmospheric dispersion model AERMOD to calculate the contribution of either fuel-technology configuration to ambient primary PM2.5 in a 10 km x 10 km region surrounding the facility, and we quantified the incremental contribution to population mortality and morbidity. We assigned economic values to health outcomes and compared the health benefits of the lower-emitting technology with the incremental costs. RESULTS: In total, the incremental annualized cost of the lower-emitting pellet boiler was $190,000 greater, driven by a greater cost of the pellet fuel and pollution control technology, offset in part by reduced fuel storage costs. PM2.5 emissions were a factor of 23 lower with the pellet boiler with electrostatic precipitator, with corresponding differences in contributions to ambient primary PM2.5 concentrations. The monetary value of the public health benefits of selecting the pellet-fired boiler technology with electrostatic precipitator was$1.7 million annually, greatly exceeding the differential costs even when accounting for uncertainties. Our analyses also showed complex spatial patterns of health benefits given non-uniform age distributions and air pollution levels. CONCLUSIONS: The incremental investment in a lower-emitting staged combustion pellet boiler with an electrostatic precipitator was well justified by the population health improvements over the conventional wood chip technology with a multicyclone, even given the focus on only primary PM2.5 within a small spatial domain. Our analytical framework could be generalized to other settings to inform optimal strategies for proposed new facilities or populations.This research was supported by the New York State Energy Research and Development Authority (NYSERDA), via an award to the Northeast States for Coordinated Air Use Management (Agreement #92229). The SCICHEM work of KMZ was supported by the Electric Power Research Institute (EPRI)

MR imaging–derived oxygen-hemoglobin dissociation curves and fetal-placental oxygen-hemoglobin affinities

PURPOSE: To generate magnetic resonance (MR) imaging–derived, oxygen-hemoglobin dissociation curves and to map fetal-placental oxygen-hemoglobin affinity in pregnant mice noninvasively by combining blood oxygen level–dependent (BOLD) T2* and oxygen-weighted T1 contrast mechanisms under different respiration challenges. MATERIALS AND METHODS: All procedures were approved by the Weizmann Institutional Animal Care and Use Committee. Pregnant mice were analyzed with MR imaging at 9.4 T on embryonic days 14.5 (eight dams and 58 fetuses; imprinting control region ICR strain) and 17.5 (21 dams and 158 fetuses) under respiration challenges ranging from hyperoxia to hypoxia (10 levels of oxygenation, 100%–10%; total imaging time, 100 minutes). A shorter protocol with normoxia to hyperoxia was also performed (five levels of oxygenation, 20%–100%; total imaging time, 60 minutes). Fast spin-echo anatomic images were obtained, followed by sequential acquisition of three-dimensional gradient-echo T2*- and T1-weighted images. Automated registration was applied to align regions of interest of the entire placenta, fetal liver, and maternal liver. Results were compared by using a two-tailed unpaired Student t test. R1 and R2* values were derived for each tissue. MR imaging–based oxygen-hemoglobin dissociation curves were constructed by nonlinear least square fitting of 1 minus the change in R2*divided by R2*at baseline as a function of R1 to a sigmoid-shaped curve. The apparent P50 (oxygen tension at which hemoglobin is 50% saturated) value was derived from the curves, calculated as the R1 scaled value (x) at which the change in R2* divided by R2*at baseline scaled (y) equals 0.5. RESULTS: The apparent P50 values were significantly lower in fetal liver than in maternal liver for both gestation stages (day 14.5: 21% ± 5 [P = .04] and day 17.5: 41% ± 7 [P < .0001]). The placenta showed a reduction of 18% ± 4 in mean apparent P50 values from day 14.5 to day 17.5 (P = .003). Reproduction of the MR imaging–based oxygen-hemoglobin dissociation curves with a shorter protocol that excluded the hypoxic periods was demonstrated. CONCLUSION: MR imaging–based oxygen-hemoglobin dissociation curves and oxygen-hemoglobin affinity information were derived for pregnant mice by using 9.4-T MR imaging, which suggests a potential to overcome the need for direct sampling of fetal or maternal blood. Online supplemental material is available for this article