Unicompartmental or total knee replacement? Five-year results of a prospective, randomised trial of 102 osteoarthritic knees with unicompartmental arthritis

We randomised 102 knees suitable for a unicompartmental replacement to receive either a unicompartmental (UKR) or total knee replacement (TKR) after arthrotomy. Both groups were well matched with a predominance of females and a mean age of 69 years. Patients in the UKR group showed less perioperative morbidity, but regained knee movement more rapidly and were discharged from hospital sooner. At five years, two UKRs and one TKR had been revised; another TKR was radiologically loose. All other knees appeared to be clinically and radiologically sound. Pain relief was good in both groups but the number of knees able to flex > or =120 degrees was significantly higher in the UKR group (p < 0.001) and there were more excellent results in this group. Our findings have shown that UKR gives better results than TKR and that this superiority is maintained for at least five years.     

Log-domain synthesis of nth order universal filter

In this paper a synthesis approach for an nth-order universal log-domain filter comprising lowpass (LP), highpass (HP) and bandpass(BP) filtering functions is proposed. The approach is simple and the method of extending the approach to two uncommon filtering functions, lowpass notch (LPN) and high pass notch (HPN), is also given. The second, fourth and sixth-order universal log-domain filters are designed using log-exponential relationship between voltage and current of bipolar junction transistors (BJT) for the verification of approach. The performance of proposed universal filter and that of extended LPN and HPN was verified through simulation results.     

A continuous stirred tank heater simulation model with applications

This article presents a first principles simulation of a continuous stirred tank heater pilot plant at the University of Alberta. The model has heat and volumetric balances, and a very realistic feature is that instrument, actuator and process non-linearities have been carefully measured, for instance to take account of the volume occupied by heating coils in the tank. Experimental data from step testing and recordings of real disturbances are presented. The model in Simulink and the experimental data are available electronically, and some suggestions are given for their application in education, system identification, fault detection and diagnosis.     

Fracturing at contact surfaces subjected to normal and tangential loads

A variety of rock engineering problems including drilling, cutting, abrasion, and milling involve rock tool contact and indentation. The pattern of indentation fractures and the role of slip conditions, surface roughness, tool radius and initial flaw size for an arbitrarily loaded contact are not fully known. The present paper aims to identify the elastic stress field for a contact subjected to both normal and tangential loads, and evaluate the condition for the fracture initiation and propagation. Stress fields within two spheres at contact are available when either only normal load is applied or when tangential load causes full-slip conditions. It is shown here that through appropriate superposition of the above two solutions, the stress field under partial-slip conditions, as well as during the unloading of tangential force may be determined. Maximum tensile stress increases significantly under partial-slip conditions as compared to the full-slip case even though the same magnitude of tangential force is applied. The location of maximum tensile stress moves inward from the trailing edge as the tangential force is unloaded. The stress-intensity factors for a penny-shaped crack which initiates at the contact periphery, and follows the minimum principal stress trajectory are obtained and utilized to study indentation fracturing. The dependency of critical loads on initial flaw size, indenter radius and slip conditions is quantified. The predictions of fracture density and spacing under a sliding indenter are achieved through a simple estimate of shielding interaction between adjacent fractures. Relation of these evenly spaced fractures with the formation of wear grooves on sliding surfaces is discussed.     

Pharmacokinetics of oral and intravenous dolasetron mesylate in patients with renal impairment

In an open-label, randomized, two-way complete crossover study, the influence of renal impairment on the pharmacokinetics of dolasetron and its primary active metabolite, hydrodolasetron, were evaluated. Patients with renal impairment were stratified into three groups of 12 based on their 24-hour creatinine clearance (Cl(cr)): group 1, mild impairment (Cl(cr) between 41 and 80 mL/min); group 2, moderate impairment (Cl(cr) between 11 and 40 mL/min); and group 3, endstage renal impairment (Cl(cr) < or = 10 mL/min). Twenty-four healthy volunteers from a previous study served as the control group. Each participant received a single intravenous or oral 200-mg dose of dolasetron mesylate on separate occasions. Serial blood samples were collected up to 60 hours after dose for determination of dolasetron and hydrodolasetron, and urine samples were collected in intervals up to 72 hours for determination of dolasetron, hydrodolasetron, and the 5' and 6'-hydroxy metabolites of hydrodolasetron. Because plasma concentrations were low and sporadic, pharmacokinetic parameters of dolasetron were not calculated after oral administration. Although some significant differences in area under the concentration-time curve (AUC0-infinity), volume of distribution (Vd), systemic clearance (Cl), and elimination half-life (t1/2) of the parent drug were observed between control subjects and patients with renal impairment, there were no systematic findings related to degree of renal dysfunction. The elimination pathways of hydrodolasetron include both hepatic metabolism and renal excretion. Consistent increases in mean Cmax, AUC0-infinity, and t1/2 and decreases in renal and total apparent clearance of hydrodolasetron were seen with diminishing renal function after intravenous administration of dolasetron mesylate. No consistent changes were found after oral administration. Urinary excretion of hydrodolasetron and its metabolites decreased with decreasing renal function, but the profile of metabolites remained constant. Dolasetron was well tolerated in all three groups of patients. Based on these findings, no dosage adjustment for dolasetron is recommended in patients with renal impairment.     

Predictions of comulative damage for concrete and reinforced concrete

Nonlinear damage evolution equation is suggested to predict fatigue life of plain concrete subjected to sequential, constant amplitude loading. This approach seems to eliminate the nonconservative aspect of the linear damage law (the Miner hypothesis) and is based on the observed shape of the damage growth relationship. For serviceability based design of reinforced concrete structures, a simple nonlinear relationship is developed to relate the increases in deflection and crack width with the cycle-ratio. The results compare favorably with experimental data.     

Polymer outdoor insulating materials. Part III-Silicone elastomerconsiderations

The silicone-based formulations now in use by Raychem have been specially developed for electrical insulating applications. They have undergone many years of development and optimization to yield exceptional electrical and weathering performance properties, comparable to the polyolefin copolymer materials. The intent of this article is to highlight the advantages of properly formulated silicone materials in outdoor insulating applications     

Prevalence of microalbuminuria in diabetic subjects

Total 193 diabetic patients were investigated to assess the prevalence of microalbuminuria. Urinary albumin excretion rate (UAER) was measured by radioimmunoassay (RIA) on 3 hours urine samples. The prevalence of microalbuminuria (UAER) > 15 micrograms/min was 41%. Microalbuminuria was commonly observed in patients having diabetes for more than 5 years. A significant correlation was found between duration of diabetes and microalbuminuria (p < 0.01). Glycemic control (fasting and postprandial blood sugar) did not show any correlation with UAER, whereas blood urea (r.39, p < 0.01), creatinine (r.26, p < 0.05) and chloride (r.24, p < 0.05) were positively correlated. A significant correlation was found between raised blood pressure and UAER (p < 0.01).     

Prediction of heat transfer during boiling of cryogenic fluids flowing in tubes

Data from eleven sources for nitrogen, neon, helium, and argon boiling in horizontal and vertical tubes were compared with the correlations of Shah and Klimenko as well as the superposition correlation of Rohsenow. Best agreement was found with the Shah correlation which agrees with nine of the data sets. Each of the other two correlations gives satisfactory agreement with only four of the twelve data sets. The results of data analysis are presented and discussed.     

Differentiated reliability in optical networks: theoretical and practical results

This paper presents both theoretical and experimental studies carried on wavelength-division multiplexing (WDM) networks with arbitrary (mesh) topology that provide optical circuits with differentiated reliability (DiR). Reliability is obtained by means of a modified shared path protection (SPP) switching scheme-here referred to as SPP-DiR. As explained in the paper, SPP-DiR networks provide multiple degrees of circuit reliability that satisfy client-specific reliability requirements in a cost-effective way. The theoretical study first defines the problem of optimally designing SPP-DiR WDM networks. It then presents a time-efficient suboptimal algorithm that determines the routing and the reliability degree of each demand in the given traffic matrix by applying both the conventional SPP and the SPP-DiR scheme. When compared to dedicated path protection switching, results obtained for the pan-European network using the proposed algorithm indicate cost reductions of about 16% when SPP is applied, and up to 34% when SPP-DiR is applied. The experimental study describes the /spl Omega/ testbed-a WDM optical circuit-switched mesh network with an IP control plane-which is believed to be the first testbed ever built that makes use of the SPP-DiR scheme. Experimental results performed on the /spl Omega/ testbed report restoration times of the optical circuits-disrupted by a fiber fault-that are few tens of milliseconds.