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Paired equine third metacarpal bones were drilled and tapped for 4.5 mm and 5.5 mm cortical screws. Tapping was done by hand or with an air-driven reversible orthopedic drill. Screws were inserted and subjected to extraction forces to failure of the osseous threads or the screws. There was no difference in holding power of either screw size between hand-tapped and power-tapped holes.
PURPOSE: To evaluate white matter disorders with magnetization transfer (MT) techniques. MATERIALS AND METHODS: In 46 healthy volunteers and 46 clinical patients, MT Z spectra were obtained with various continuous-wave-equivalent MT powers (B1CW) and frequency offsets. RESULTS: With B1CW of 270 Hz and 4,000-Hz frequency offset, the MT ratio of normal callosal white matter was 59.2% +/- 1.5 (standard deviation), with less than 5% contribution from direct saturation and spin locking. A small statistically significant (P < .01) regional variation in normal white matter was seen. Plaques in MS patients had a broad (or wide) range of MT ratios; normal appearing white matter had a slightly reduced MT ratio. Vasogenic edema had a minimal effect on MT ratio, and radiation necrosis showed prominent reductions in MT ratio. CONCLUSION: High MT power techniques can expand the dynamic range of MT ratios, maintain a relatively pure MT effect, and be used effectively in MT imaging to evaluate white matter disorders.
We report a large-core, Yb-doped photonic crystal fiber amplifier generating diffraction-limited (M2 = 1.04), approximately 0.45 ns, approximately 8 GHz linewidth pulses with energies of 540 microJ, peak power in excess of 1.1 MW, and average power of approximately 7.2 W at a repetition rate of 13.4 kHz. The pulse peak spectral brightness exceeds 10 kW/(sr Hz cm2) and is the highest generated by a fiber source, to our knowledge.
600 mW second-harmonic blue light at 488 nm has been generated by use of a master-oscillator power amplifier diode laser system as a pump source with a maximum optical output power of 4 W in continuous-wave operation. For frequency doubling, a periodically poled MgO:LiNbO3 bulk crystal was used in a single-pass configuration. A conversion efficiency of 15% and an overall wall-plug efficiency of 4% were achieved.
Three hundred and fourteen adult upper limb amputees were reviewed retrospectively at the Ontario Workers' Compensation Board. A questionnaire was used to evaluate the use of body and electrically powered prostheses. Follow-up ranged from 1 to 49 years with a mean of 15 years. Results indicated that complete or useful acceptance of an electrically powered prosthesis was reported by 69 of 83 amputees (83%); 199 of 291 amputees (68%) used the cable operated hook, 57 of 291 (20%) used the cable operated hand and 40 of 83 (48%) used the cosmetic prosthesis. The majority of amputees used more than one prosthesis for their functional needs and should be fitted with more than one type of prosthesis. Acceptance of an upper limb prosthesis by 89% (196/220) of below-elbow, 76% (56/74) of above-elbow and 60% (12/20) of high level amputees indicates that for most upper limb amputees, their prostheses are well used and essential to their personal and employment activities.
The Wertheimer-Leeper wire code, originally developed as a surrogate for magnetic-field exposure, has been associated with childhood leukemia in several epidemiologic investigations. However, these and other studies indicate that most between-residence variability in measured magnetic fields remains unexplained by wire codes. To better understand this remaining variability, engineering and demographic data were examined for 333 underground (UG) and very-low current configuration (VLCC) single-family or duplex residences, selected from a database of nearly 1000 residences specifically because their magnetic fields are most likely affected negligibly by overhead power lines. Using linear regression techniques, four factors predictive of the log-transformed residential field were identified: the square-root of the 24-h average net service drop current (this current is equivalent to the current in the grounding system), the log of the number of service drops on the same secondary serving the residence, residence age (four categories), and area type (rural, suburban, or urban). Complete data on ground current and service drops, the two factors with the strongest individual relationships to measured fields, were available for only half of the residences in the sample. However, these data were determined to be "missing at random" according to established statistical criteria. The full-sample or "composite" models thus relied on a method similar to regression imputation, accounting for missing data with binary dummy variables. When applied to the samples from which they were derived, these models accounted for 25% of the variance of the log-spot-measured magnetic field values in the full sample, while models that considered only those residences with complete data (n = 167) explained about 35%. The model validated well against a sample of 201 ordinary low current configuration (OLCC) homes selected from the same database.
The growing importance of IT is reflected in Modem Healthcare's third annual ranking of the 100 Most Powerful People in Healthcare. The person topping the 2004 list is a newcomer who recently vaulted to prominence. Who is he, and what other industry movers and shakers made the ranking.
An evaluation of exposure to dust of workers employed at typical work-stands in power industry plants was made. Mean concentrations of respirable dust determined at 14 different work-posts range from 0.45 to 8.95 mg/m3, and of total dust from 1.55 to 85.0 mg/m3. Mean content of free crystalline silica in dust samples is less than 10%. At the work-stands where ash dust was encountered, the presence of respirable fibres at concentration below 0.2 fibre/cm3 was observed. In all ash samples alpha-quartz and mullite were found: in some of them also kaolinite and orthoclase were traced. Only at five out of all 14 work-stands examined mean concentration of respirable dust was lower than the hygienic standard value.
A Q-switched Nd:YAG laser apparatus has been used in the treatment of a number of pathological conditions of the anterior and posterior segments of the human eye. This laser system may be driven in a free running mode, thereby allowing variation of pulse duration over a range of 12 ns to 10 ms. With increasing pulse duration, non-linear mechanical damage patterns characteristic of the biological effects at the lower exposure duration range become unimportant when compared to the so-called thermal effects met at the upper pulse duration range. The thermal damage mechanisms may be useful when applied together with the mechanical damage mechanism, for instance when iris perforations are intended. Because the Wise-Witter irradiation method for the treatment of open angle glaucoma depends on low power, thermal mechanisms, this instrument may also be useful for the treatment of this disease entity. This same irradiation mode may also be applied to at least some irradiation tasks of the retina and choroid.
OBJECTIVES: To evaluate and compare the safety and effectiveness of two noncontact laser regimens for the treatment of human benign prostatic hyperplasia (BPH), and to assess the impact of the spatial distribution of the laser-induced lesions on treatment outcome. METHODS: This was a prospective, double-blind, randomized study that included 29 patients with BPH (both the patients and the study physician assistant in charge of the follow-up evaluation were blinded to the treatment rendered). The patients were randomized to receive either a 15 W for 180 s (15 patients) or 50 W for 60 s (14 patients) laser regimen (powers measured at the fiber tip). There were two study phases for each treatment group: the irradiated sites were not overlapping during the first phase (lesions 1.5 cm apart), and were overlapping during the second phase (lesion less than 1.0 cm apart). RESULTS: Morbidity was minimal in both groups. At 1 year of follow-up, there was significant improvement of the American Urological Association-7 symptom score, the peak urinary flow rate, and the postvoid residual in both treatment groups. These improvements were not statistically significantly different regardless of time or the phase of the study for the two treatment groups. There were 3 treatment failures, 2 of whom were later successfully re-treated with larger amounts of laser energy. Furthermore, the peak flows in the second phase of the study were statistically significantly higher than those in the first phase of the study, regardless of the treatment group. CONCLUSIONS: Our results suggest that both the 15 W for 180 s and the 50 W for 60 s are equally safe and effective treatments for BPH. Perhaps more importantly, they also suggest that the spatial distribution of lesions and overlapping of treated (irradiated) sites has significant impact on treatment outcome.
The output from physiotherapy ultrasound (US) probes is usually measured using a radiation force balance. Some balances are sealed and incorporate a membrane coupling window. The probes are highly resonant, and the output may be affected by changes in acoustic loading caused by the membrane. A model has been developed to examine this effect, and predicts that a polythene membrane 100-microm thick can change the output power by up to 17%.
Foucault's genealogies and archeologies provide occasions in which one may come to know the powers, accidents, and influences that have structured a particular knowledge or discipline. The Birth of the Clinic shows the development of modern medicine in a process by which rational inference and emphasis on the history of a disease are replaced by pathological anatomy. In modern anatomy, the corpse, not reason, became the "space" of modern medical knowledge. In this "space" developed a confederation of dead body, knowledge, trained and noninferential gaze, organic unity, and the increased importance of bodily space instead of physical time. The discussion shows how Foucault's genealogy of modern medicine is influenced by and overcomes the knowledge that it describes. In this context, his genealogy is also shown to be self-overcoming and to raise important questions for medical ethics when ethical thought is conceived within the structures of knowledge that have been exposed by the genealogy.
The importance of genetic and environmental factors in muscular strength and power variation has been reported in the last two decades. However, there is a paucity of data on gender- and age-specific estimates of heritabilities. Linkage and association studies that aim to identify genes and gene variants for muscular strength are only emerging.
We show that Brownian motion of a one-dimensional domain wall in a large but finite system yields a omega(-3/2) power spectrum. This is successfully applied to the totally asymmetric simple exclusion process with open boundaries. An excellent agreement between our theory and numerical results is obtained in a frequency range where the domain wall motion dominates and the discreteness of the system is not effective.
1. Length-tension relationships and work output were investigated in the intact, dorso-ventral flight muscle of the bumblebee Bombus terrestris. The muscle is an asynchronous muscle. Like other asynchronous flight muscles, it has high resting stiffness and produces relatively low active force in response to tetanic stimulation. 2. The muscle shows shortening deactivation and stretch activation, properties that result in delayed force changes in response to step changes in length, a phase lag between force and length during imposed sinusoidal strain and, under appropriate conditions, positive work output during oscillatory length change. 3. Work loops were used to quantify work output by the muscle during imposed sinusoidal oscillation. The curves relating net work per cycle with muscle length, oscillatory strain and oscillatory frequency were all roughly bell-shaped. The work-length curve was narrow. The optimum strain for net work per cycle was approximately 3 %, which is probably somewhat greater than the strain experienced by the muscle in an intact, flying bumblebee. The optimum frequency for net work output per cycle was 63 Hz (30 °C). The optimum frequency for power output was 73 Hz, which agrees well with the normal wing stroke frequency if allowance is made for the elevated temperature (approximately 40 °C) in the thorax of a flying bumblebee. The optimal strain for work output was not strongly dependent on oscillation frequency. 4. Resilience (that is the work output during shortening/work input during lengthening) for unstimulated muscle and dynamic stiffness (=stress/strain) for both stimulated and unstimulated muscles were determined using the strain (3 %) and oscillation frequency (64 Hz) which maximized work output in stimulated muscles. Unstimulated muscle is a good energy storage device. Its resilience increased with increasing muscle length (and increasing resting force) to reach values of over 90 %. The dynamic stiffness of both stimulated and unstimulated muscles increased with muscle length, but the increase was relatively greater in unstimulated muscle, and at long muscle lengths the stiffness of unstimulated muscle exceeded that of stimulated muscle. Effectively, dynamic stiffness is reduced by stimulation! This is taken as indicating that part of the stiffness in an unstimulated muscle reflects structures, possibly attached cross bridges, whose properties change upon stimulation.
AIM: To investigate the characteristics of the vascularity of hepatic metastasis. METHODS: Six New Zealand rabbits, weighing averagely 2.7+/-0.4 kg, were selected and operated to establish hepatic VX2 tumor carrier model. Hepatic VX2 tumors were then imaged with conventional B mode US, second harmonic imaging (SHI), color Doppler flow imaging (CDFI), power Doppler imaging (PDI) and harmonic PDI by a transducer S8 connected to HP-5 500 ultrasound system. A kind of self made echo contrast agent was intravenously injected at a dose of 0.01 mL/kg through ear vein, and then the venous passage was cleaned with sterilized saline. RESULTS: Totally, 6 hypoechoic lesions and 3 hyperechoic lesions were found in the six carrier rabbits with a mean size about 2.1+/-0.4 cm under conventional B mode ultrasound, they were oval or round in shape with a clear outline or a hypoechoic halo at the margin of the lesions. Contrast agent could not change the echogenicity of the lesions under conventional B mode and SHI, however, it could greatly increase the flow sensitivity of the lesions under PDI and harmonic PDI. Nutrient artery of these metastatic lesions might also be well depicted under contrast enhanced PDI and harmonic PDI. CONCLUSION: Our result suggested that contrast enhanced PDI, especially harmonic PDI, was a promised method in the detection of vascularity of hepatic tumor nodules.
The present study examined whether a six-week resistance training program would influence the critical power (CP) function, time to exhaustion (TE) at CP and/or peak oxygen uptake (VO2 peak). The CP function is believed to provide an index of endurance ability (CP given by the slope), and anaerobic work capacity (the y-intercept). Eight healthy, untrained males undertook lower-body resistance training (90 min/day, 3-4 times/wk) for six weeks; eight controls refrained from resistance or endurance training for the same period. Before and immediately following the training period, subjects completed three trials to determine their CP function, a test of VO2 peak, a one-repetition maximum (1-RM) leg press test and TE at their CP. Training significantly increased both 1-RM leg press (28.6%, P < 0.05) and the y-intercept (34.9%, P < 0.05) while no changes in CP, VO2 peak or TE (p > 0.05) were found. Changes in the y-intercept following resistance training were negatively correlated with changes in the CP (r = -0.94, p < 0.05, N = 8). The present data show that the y-intercept of the CP function is sensitive to, and modified by, six weeks of resistance training. Given that resistance training had no significant influence on CP, TE at CP or VO2 peak, the present study has also shown that six weeks of resistance training will not alter indices of endurance ability. The negative relationship between changes in the y-intercept and CP exposes a potential limitation of the linear CP function when evaluating changes in endurance ability following an intervention which significantly alters the y-intercept.
Previously established data on average forces applied to various brushing instruments during in vivo toothbrushing were incorporated into a laboratory abrasion model. The apparatus included a specially constructed and standardized brushing machine and utilized an acrylic resin substrate. Three powered brushing instruments (Rota-dent, Interplak and Braun Oral-B Plaque Remover) and a manual toothbrush (Oral-B P40), were compared in this model. The system demonstrated excellent precision and could distinguish between brushing instruments with as little as 10% difference in abrasivity. It was found that brushing abrasivity increased in the order of Rota-dent < Braun < Interplak.