Neural network based tracking control of a flexible macro-micro manipulator system.

In this paper, we address the problem of stable tracking control of a flexible macro-micro manipulator (M(3)) system. A two-layer neural network is utilized to approximate the nonlinear robot dynamic behavior of the M(3) system, and the controllers for the macro and micro arms are developed without any need for prior knowledge of the dynamic model of the controlled M(3) system. A learning algorithm for the neural network using Lyapunov stability theory is derived. It is shown that both the tracking error and the weight-tuning error are uniformly ultimately bounded under this new control scheme. Simulation results are presented and compared to those obtained using a PD controller.     

Ulcer of the tongue as a presenting feature of pulmonary tuberculosis

Oral tuberculosis is very rare and when present they are usually secondary to pulmonary tuberculosis. Tuberculous lesions of the tongue have become so infrequent that they are virtually a forgotten disease entity and may pose a diagnostic problem. The case reported in this paper emphasizes the importance of including tuberculosis in the differential diagnosis of any chronic oral ulcer. The low number of oral infections by M. tuberculosis could be due to underreporting.     

Increased Ventricular Vulnerability in a Chronic Ethanol Model Despite Reduced Electrophysiologic Responses to Catecholamines

An increased incidence of sudden death has been reported in chronic alcoholism. To assess electrical vulnerability of the heart, action potential responses, and the role of the sympathetic system, a well-nourished canine model has been studied intact under chloralose anesthesia after 1 year of ethanol consumption at 36% of caloric intake. Two alcoholic groups were compared with controls (Group 1). In Group 2 myocardial vulnerability was assessed after chronic EtOH and superimposed acute administration. In Group 3 basal vulnerability was related to circulating norepinephrine and release of neurohormone from the myocardium. Subsequently the responsiveness to catecholamine infusion was determined. To assess vulnerability an electrode catheter was placed in the right ventricular apex. The basal ventricular fibrillation threshold (VFT) was reduced to 27 +/- 3 ma in Group 2 versus 43 +/- 1.0 in Group 1. Acute infusion of ethanol in Group 2 further reduced the threshold. Group 3 had a reduced basal VFT. Baseline arterial plasma levels of norepinephrine were 8-fold higher and coronary venous levels 13 times higher in the alcoholic group than in Group 1. However, VFT was not responsive to infused epinephrine, compared with Group 1 controls. In vitro study of superfused ventricular tissue from Group 3 revealed that basal action potential amplitude, overshoot, and resting potential were comparable with normals. Basal repolarization time (90%) was 198 +/- 12 msec in Group 3 versus 215 +/- 6 msec in Group 1 (p less than 0.05). After acute EtOH, repolarization time was shortened to 170 +/- 8.6 in Group 1 at 90 mg% ethanol (p less than 0.002), with minimal further change up to 280 mg%.(ABSTRACT TRUNCATED AT 250 WORDS)     

High-resolution imaging of progressive articular cartilage degeneration.

The objective of this study was to develop and verify a new technique for monitoring the progression of osteoarthritis (OA) by combining a rat model with the imaging modality optical coherence tomography (OCT). Time-sequential, in vivo, OCT imaging was performed on the left femoral condyles of 12 Wistar rats following sodium-iodoacetic acid-induced OA progression. The right femoral condyles (untreated) were also imaged and served as controls. Imaging was performed on days 0, 10, 20, 30, and 60 with an OCT system capable of acquiring images at four frames per second and an axial resolution of 5 microm. Progressive changes were analyzed using an OA scoring system. OCT successfully identified progressive cartilage degeneration as well as alteration of the cartilage/bone interface. Significant changes to both of these structures were observed in the sodium-iodoacetic acid-injected condyles. Structural changes detected with OCT were confirmed histologically. OCT in combination with a well-known model used in arthritis research represents a powerful tool for following degenerative joint disease progression in a given animal by detecting changes to the cartilage/bone interface and articular cartilage.     

The multiple drug resistance gene,MDR1: Expression at the protein and RNA levels

A comparison of three different approaches to detect MDR₁ expression in myeloid leukemia cells was undertaken. With respect to the 4 different antibodies studied, a high proportion of false positive reactions were detected. Substantial discordance between MDR₁ expression as indicated by Northern blot analysis, PCR, and immunohistochemistry was found. These findings complicate the clinical interpretation of data derived from these methods.     

Quantitative assessment of variables that influence soft-tissue electrovaporization in a fluid environment

Objectives. To evaluate the process of soft-tissue electrovaporization and to study variables that affect tissue clearance rates in a laboratory setting, in order to identify parameters that can optimize transurethral electrovaporization of the prostate.Methods. Fresh bovine skeletal muscle, equivalent in impedance and surface properties to the human prostate, was submerged in 3.3% sorbitol solution and electrovaporized with a grooved monopolar electrode attached to the weighted arm of a linear actuator. The effects of excursion rate, applied mechanical load, power setting, electrode configuration, and generator performance on the volume of tissue removed, were assessed.Results. Tissue removal increased significantly when electrode excursion rate was slowed from 25 to 15 mm/s (P <0.05) and then to 10 mm/s (P <0.05); when the load was increased from 20 to 50 g (P <0.005); and when dial power was increased from 120 to 150 W (P <0.01). Tissue removal was generator dependent. There was no significant difference between the Force 40 and the Force 2 (P > 0.4), but a new computer-controlled constant power output generator (Force FX) did significantly improve tissue vaporization at an equivalent power setting (P <0.005 and P <0.01, respectively). Tissue removal was also dependent upon electrode configuration, with the VaporTrode-Grooved Bar removing significantly more tissue than either an ungrooved roller bar of equivalent size or 2-mm smooth roller ball, respectively, both after a single pass (P <0.001 and P <0.05) and after five repeated passes (P <0.05 and P <0.005). The histologic depth of tissue thermal effect was less than 1 mm, but it was 38% greater for the VaporTrode-Grooved Bar (0.68 mm) than for the standard cutting loop (0.5 mm, P <0.01).Conclusions. Using a novel method to quantify tissue removal, we have demonstrated that electrode configuration, excursion rate, applied load, power setting, and generator performance are interdependent factors that influence the efficacy of the electrovaporization process in a fluid environment.     

Aggressive behaviour in elderly psychiatric inpatients.

We describe the types of aggressive behaviour and determine their prevalence in a sample of hospitalized elderly psychiatric patients. Data were obtained by nurse ratings of aggressive behaviour using the recently developed Rating Scale for Aggressive Behaviour in the Elderly; 90 patients were rated over a 3-d period. Nearly half the sample were at least mildly aggressive; the frequencies of some specific types of aggressive behaviour were high. In contrast, the frequency of injuries and the use of restraints and medication for aggressive behaviour were low. Some correlates of the aggressive behaviour were also analysed.     

Single-stage repair of severe hypospadias using bladder mucosa graft

Our experience of single-stage repair of severe hypospadias (penoscrotal, scrotal, and perineal) in 30 children using urinary bladder mucosa for urethroplasty is reported. These children had severe chordee, small prepuce, and often ventral transposition of the penis with bifid scrotum where Devine and Horton, Asopa, or Duckett techniques are not so suitable. The graft uptake was uniformly satisfactory. Ten patients had complications; most of the fistulae healed spontaneously. Surgical intervention was required in 2 cases only: 1 for a fistula and another for a stricture with fistula. Meatal stenosis, seen in 4 cases, led to delayed distal fistulae in 2, which healed spontaneously with meatal dilatation. Regular dilatation of the external meatus is recommended to prevent this problem.