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A general routine exists for estimating dioptric power from any number of measurements of sagitta, lens thickness, meridional curvature or power, and prismatic effect. This paper shows how the routine is modified when among the measurements there are measurements of dioptric power itself.
The Fusion Free-Electron Maser (FFF) is the prototype of a high-power, tunable source of mm-wave radiation, for use on fusion plasma devices. In previous experiments a net output power of 730 kW at 206 GHz was generated in short pulses. The present experiment has been equipped with a system to recover the charge and energy of the spent electron beam. We present experimental results which show output of mm-wave radiation at constant power level during the full pulse length, as well as single-frequency operation; even though the cavity is highly overmoded; the latter is reached by effective suppression of spurious modes by the feedback system.
General or local variations of the refractive elements in the eye, called irregular astigmatism, may manifest as non-orthogonal meridians when each principal meridian on the front surface of a cornea is independently aligned with the focussed mires of a keratometer. These are examples of astigmatic systems that are thick. The representation of power along the principal meridians is not suitable for quantitative work. The purpose of this research note is to convert power along principal meridians that can be non-orthogonal, to the coordinates of the power matrix that are suitable for quantitative analysis.
We trained two starlings (Sturnus vulgaris) to fly in a wind tunnel whilst wearing respirometry masks. We measured the metabolic power (P(met)) from the rates of oxygen consumption and carbon dioxide production and calculated the mechanical power (P(mech)) from two aerodynamic models using wingbeat kinematics measured by high-speed cinematography. P(met) increased from 10.4 to 14.9 W as flight speed was increased from 6.3 to 14.4 m s(-1) and was compatible with the U-shaped power/speed curve predicted by the aerodynamic models. Flight muscle efficiency varied between 0.13 and 0.23 depending upon the bird, the flight speed and the aerodynamic model used to calculate P(mech). P(met) during flight is often estimated by extrapolation from the mechanical power predicted by aerodynamic models by dividing P(mech) by a flight muscle efficiency of 0.23 and adding the costs of basal metabolism, circulation and respiration. This method would underestimate measured P(met) by 15-25 % in our birds. The mean discrepancy between measured and predicted P(met) could be reduced to 0.1+/-1.5 % if flight muscle efficiency was altered to a value of 0.18. A flight muscle efficiency of 0.18 rather than 0.23 should be used to calculate the flight costs of birds in the size range of starlings (approximately 0.1 kg) if P(met) is calculated from P(mech) derived from aerodynamic models.
Continuous-wave 457 blue laser emission at powers as high as 4.6 W is achieved by using a fiber-coupled laser diode array with a power of 30 W to pump 0.1 at. % low-doped bulk Nd:YVO4 crystal, with intracavity frequency doubling in a 15 mm long type I critical phase-matched LiB3O5 (LBO) crystal in a compact three-fold cavity with a length of less than 100 mm. The optical-optical conversion efficiency is greater than 15.3%, and the stability of the output power is better than 3% for an hour.
Nearly all tractor PTO arrangements used today consist of a rotating mechanical shaft with two or more universal joints and splined couplings. Although this method of power transfer has been the standard for decades, it continues to be a hazard to farm workers. Commonly, PTO accidents involve the snagging of clothes, resulting in the victim being rapidly and violently drawn into (and around) the rotating shaft. Entanglement injuries are both common and severe in the agricultural workforce, with poor shielding maintenance as a contributing factor. If PTO loads were driven with fluid power, this entanglement hazard would be eliminated. With high-pressure injection injury being the principal hazard, the fluid power alternative appears to pose a lower risk in terms of both frequency of occurrence and severity of injury.
INTRODUCTION: An examiner-blinded, randomized, parallel, three-cell, controlled clinical trial was conducted to compare the efficacy of a new powered toothbrush (Hydrabrush) to that of two presently marketed power brushes (Oral-B and Sonicare) in reducing stain, supragingival plaque, gingivitis and the signs of periodontitis while monitoring safety. METHODS: One hundred ten subjects were randomly assigned to three groups (35--Oral-B group, 36--Sonicare group, and 39--Hydrabrush group). Subjects were instructed to use the assigned powered toothbrush according to the manufacturer's instructions for 2-minutes duration twice per day. Clinical examinations conducted at baseline and at weeks 4, 8, and 12 included the following parameters: (1) oral tissues; (2) staining; (3) plaque index; (4) gingivitis; (5) probing depth; (6) clinical attachment loss; and 7) bleeding on probing. RESULTS: The results showed that the body intensity and extent of stain and the gingival intensity and extent of stain at 8 and 12 weeks, respectively, were significantly less in the Hydrabrush group compared with the Sonicare group. The modified gingival index (MGI) in all groups significantly decreased over the 12 weeks. However, the groups did not differ from each other statistically. At 4, 8 and 12 weeks, the Hydrabrush group had statistically significantly less plaque than the Sonicare group. At 4 weeks, the Hydrabrush group had statistically significantly lower mean probing depth than both the Oral-B and Sonicare groups. At 8 and 12 weeks, the Hydrabrush group had statistically significantly lower mean probing depths than the Sonicare group. With regard to mean percentage of sites with probing depth > or =4 mm, the Hydrabrush group had statistically significantly fewer sites > or =4 mm at 4, 8 and 12 weeks. Differences among the groups in clinical attachment loss at 4, 8 and 12 weeks were representative of small imbalances at baseline. No differences were seen among the treatment groups with regard to gingival recession and bleeding on probing. CONCLUSIONS: With the exception of clinical attachment loss, all subject groups were balanced for all measured clinical parameters at baseline. Tooth stain became significantly less in the Hydrabrush group compared with the Sonicare group at 8 and 12 weeks. At all examinations, the Hydrabrush group had statistically significantly less plaque than the Sonicare group. At 4 weeks, the Hydrabrush group had statistically significantly lower mean probing depth than both the Oral-B and Sonicare groups, and at 8 and 12 weeks, the Hydrabrush group had statistically significantly lower mean probing depth than the Sonicare group. With regard to mean percentage of sites with probing depth > or =4 mm, the Hydrabrush group had statistically significantly fewer sites > or =4 mm when compared to the other two tested brushes at all examinations. No differences were seen among the treatment groups with regard to gingival recession and bleeding on probing and none of the tested brushes caused any adverse reactions.
The Powered Gait Orthosis (PGO) is a powered exoskeleton developed as an experimental device to provide bipedal locomotion to individuals with physical impairment. The current prototype consists of a single degree of freedom (DOF) system for each leg, providing power and proper displacement required for bipedal locomotion. It is the goal of this research to obtain the forces that are present in the device while it is in normal operation. In addition, the time ratio of the hip function generator has been varied to determine the effect that different time ratios have on system forces and required user energy. The time ratio is the relationship between the time period that the thigh is in swing phase and when it is in support phase. Knowing the forces in the system and the optimal time ratio will allow for the design and construction of a feasible device for the rehabilitation and assistance of individuals who have lost the ability to walk.
Mechanical oral hygiene instruments are intended to aid in the removal of stain and dental plaque from tooth surfaces. Certain home hygiene procedures, however, can lead to soft and hard tissue trauma. Power assisted brushing instruments are gaining in popularity, yet there is limited information on the interaction of these home care instruments with commercial dentifrices, and the resultant impact on oral tissues. In this study, the average forces applied during in vivo toothbrushing were determined for three powered brushing instruments (Rota-dent, Interplak and Braun Oral-B Plaque Remover) and a manual toothbrush (Oral-B P40). The Rota-dent instrument was found to be used with the lowest brushing pressure followed, in order, by the Braun Oral-B Plaque Remover. Interplak and the manual toothbrush. The average amount of dentifrice applied to the three powered brush heads was directly related to the size of the head, with Rota-dent typically receiving the least and Interplak the most applied dentifrice.
The continuous emission monitoring system (CEMS) can monitor flue gas emissions continuously and instantaneously. However, it has the disadvantages of enormous cost, easily producing errors in sampling periods of bad weather, lagging response in variable ambient environments, and missing data in daily zero and span tests and maintenance. The concept of a predictive emission monitoring system (PEMS) is to use the operating parameters of combustion equipment through thermodynamic or statistical methods to construct a mathematic model that can predict emissions by a computer program. The goal of this study is to set up a PEMS in a gas-fired combined cycle power generation unit at the Hsinta station of Taiwan Power Co. The emissions to be monitored include nitrogen oxides (NOx) and oxygen (O2) in flue gas. The major variables of the predictive model were determined based on the combustion theory. The data of these variables then were analyzed to establish a regression model. From the regression results, the influences of these variables are discussed and the predicted values are compared with the CEMS data for accuracy. In addition, according to the cost information, the capital and operation and maintenance costs for a PEMS can be much lower than those for a CEMS.
The place of theorizing disability in everyday lives was investigated and how theorizing that is available in academic discourse can move from the ivory tower to be the "stuff" of everyday life conversations, with practical usefulness when put in the hands of nonacademic users, was discussed. Examples in which accessibility to scholarly theory resonated with families and support staff in their daily lives were provided. A rights-based theorization of disability with its corresponding feeling of power was contrasted with a relationship-based theorization with its corresponding power of feelings. The contrast is suggested to demonstrate the usefulness of drawing on theorization to expose personal theories-in-operation and invigorate personal practices of inclusion.
For unilateral below-elbow amputated children a new elbow-controlled hand prosthesis has been developed. Since the triceps of young children have insufficient power to activate normal spring-closing hands, a special mechanism with low operating power has been developed for this prosthesis. A stiff spring gives a good gripping force. When the elbow is slightly extended this spring is switched off, and by further extension the hand is opened against a weak spring. So far, six children have used this special prosthesis. Their initial enthusiasm resulted in an improved system, which is now being designed.
PURPOSE: The aim of this prospective study was to evaluate the diagnostic value of power Doppler ultrasonography (PDUS) and contrast-enhanced PDUS (CEPDUS) in the depiction and characterization of experimentally induced arthritis in the rabbit. MATERIALS AND METHODS: Thirty rabbits were divided into three groups consisting of one control group (saline injection group) and two experimental groups: a suppurative arthritis group and a chemically induced synovitis group. The same amount (1 ml) of each agent was directly injected into the right hip joint. Serial color Doppler ultrasound (CDUS), PDUS, and CEPDUS images were obtained before and after injection. RESULTS: We observed that all of the infected knees in the suppurative arthritis group with Staphylococcus aureus demonstrated an increased signal on PDUS after inoculation. A minimal power Doppler signal was presented in the chemically induced synovitis group with talc injection, but none of the control knees demonstrated any increased signals. CEPDUS was the most sensitive imaging modality for evaluating the increase of blood flows in suppurative arthritis and was subsequently followed by PDUS and CDUS. CONCLUSION: The increased signals obtained with PDUS represent increased local blood flows; therefore, this technique can be used for evaluating the degree of inflammation. Furthermore, using the contrast agent enhances the sensitivity of PDUS, and it can even be useful for differentiating borderline cases.
Disturbances of Mg2+ metabolism have been reported in association with affective disorders, seizures in eclampsia, and alcohol withdrawal. Mg2+ has been reported to have N-methyl-D-aspartate (NMDA)-antagonistic and gamma-aminobutyric acid (GABA)-agonistic properties and modulation of GABA(A)- and NMDA-dependent systems is involved in pharmacological treatment of affective disorders and seizures. We studied the effect of Mg2+ on sleep electroencephalogram (EEG) and nocturnal hormonal secretion in men. Ten normal controls were given MgSO4 (3 g MgSO4 between 2030 hours and 2100 hours, followed by 0.5 g MgSO4 per hour until 0700 hours) or placebo i.v. according to a randomized schedule. The sleep EEG was recorded from 2300 hours to 0700 hours. Blood samples were taken from 2000 hours to 0700 hours for analysis of plasma corticotropin (ACTH), cortisol, growth hormone, prolactin and melatonin. The sleep-EEG power within the spindle frequency range (11.0-12.9 Hz) showed a significant increase in the third sleep cycle, but delta power was unchanged throughout the night. ACTH concentration was suppressed between 2200 hours and 0700 hours. No changes in cortisol, growth hormone prolactin or melatonin release were found. The findings are consistent with the assumption that Mg2+ has GABA(A)-agonistic or NMDA-antagonistic effects on sleep and nocturnal hormonal secretion and hence may be useful in controlling depressive symptoms and seizures.
The aims of this study were to evaluate the ability of 3-dimensional (3-D) power Doppler angiography (3DPDA) to depict the intracranial vasculature in infants, to compare with 2-D power Doppler ultrasonography (2DPDU), and to explore the potential clinical applications of this procedure in young infants with brain disorders. We performed 3DPDA in 27 infants. 2DPDU were completed in both sagittal and coronal directions in 12 of these patients. In the other 15, only right sagittal plane images were available for comparison. Using a grading system and with only vessels with more than half of the length demonstrated included for comparison, we compared the Doppler signals of major vessels. 3DPDA could have good visualization in more than 60% of the internal carotid artery, ophthalmic artery, pericallosal artery, callosomarginal artery, internal cerebral vein, vein of Galen, and straight sinus in the sagittal plane. 3DPDA also could have good demonstration in about 50% of basilar artery in coronal plane, and posterior communicating artery, posterior cerebral artery, and lenticulostriate artery in sagittal plane. 3DPDA was better than 2DPDU in demonstrating all the major intracranial vessels in different planes, except the anterior communicating artery. In the anterior communicating artery, neither can demonstrate more than 30%.
Indexes of left ventricular systolic function that are considered relatively load-insensitive were assessed to determine their relation to the severity of heart failure symptoms and their ability to predict the outcome of idiopathic dilated cardiomyopathy. Stress, flow, power, and ejection force were calculated throughout ejection by echocardiography at rest in 35 patients with idiopathic dilated cardiomyopathy and in 20 control subjects. Patients were evaluated prospectively every 6 months for 2 years. Asymptomatic patients were separated most clearly from New York Heart Association (NYHA) class II by end-systolic stress; NYHA class II patients were separated from NYHA class III and the latter from NYHA class IV by peak rate of change of flow. Ten patients showed improvement in symptoms as well as in systolic indexes; none of them died during the follow-up. Improvement was unpredictable with the evaluated variables. One- and 2-year cardiovascular mortality rates were 17% and 26%, respectively. Patients whose condition did not improve after the first year had a 17% second-year mortality rate. Peak rate of change of power predicted death with 100% sensitivity, 56% specificity, and 64% positive predictive value in NYHA III and IV patients.
A method published elsewhere for estimating dioptric power from meridional measurements is generalized here to allow for measurements of sagitta, lens thickness, and prismatic effect as well. Measurements may be of only one type or of combinations of types. Any number of measurements may be used. Within the usual limitations of first-order optics the method always works and gives all solutions when solutions exist. When no solutions exist it gives approximate solutions called least-squares estimates. At least one least-squares estimate always exists. A wide class of ostensibly distinct problems reduces to a single standard routine that is easy to execute with matrix-handling software. If there is reason to believe that the dioptric power is of some particular form then constrained estimation may be applied to find that form.
Test-retest reliability of measurements of peak aerobic power (cycle ergometer), anaerobic power (cycle ergometer), and isokinetic muscle strength of the knee (Cybex) was established in 12 young children with cerebral palsy (spastic diplegia/tetraplegia; mean age 8.8 years) and in addition in 39 healthy controls (mean age 9.2 years). The cycle ergometer tests were found to be reliable in both the group with CP and the control group (test-retest correlations varying from 0.72 to 0.96). The isokinetic strength test in the group with CP was only reliable at 30 degrees/s, whereas in the control group high test-retest correlations were also found at 60 degrees/s and 120 degrees/s.