Target-thickness-angular-spread tables for proton and pion beams

When passing through materials, a parallel beam of charged particles is given an angular divergence by multiple Coulomb scattering processes. Convenient measures of the spreading of the scattered beam are given by the standard-deviation angle, the full-width-half-maximum angle, and the full-width-tenth-maximum angle. These tables present the thicknesses of materials that produce these three angular spreadings in the range 5 to 60 mrad. Values are given for protons with energies between 200 and 850 MeV and for pions with energies between 50 and 700 MeV. Steps of 50 MeV are employed in both cases. The target materials are He, C, Al, Ar, Ca, Fe, Zn, Ge, Kr, Zr, Ag, Cs, Hf, Au, and Pb. The tabulated values were computed from Molière theory with constants chosen to fit experimental data. Suggestions for interpolation in Z, A, particle energy, and angle are given.     

The rationale for cementless total hip replacement

Current cementing techniques of distal plugging, pulsatile water cleaning of the canal, and retrograde filling with PMMA in a low-viscous state prepared using porosity reduction techniques and then pressurized have been shown to give excellent results at 10 or more years after operation. However, physical and aging characteristics of PMMA do not guarantee that those results will hold up in the 20- to 30-year time frame. Fifteen-year experience with bony ingrowth systems indicate the development of a durable interface without PMMA, although the interface does appear more vulnerable to attack by the biologic reaction to HMWPE debris. Bone remodeling appears more favorable around proximally fixed bone ingrowth prostheses than around distally fixed prostheses. Softening of the physical characteristics of the stem tip may reduce the incidence of thigh pain. Patients with high activity potential and a life expectancy of greater than 25 years should be strongly considered for a proximally fixed bone ingrowth or ongrowth prosthesis.     

Assessment of corticosteroid-induced alkaline phosphatase isoenzyme as a screening test for hyperadrenocorticism in dogs

Quantitative determination of the corticosteroid-induced isoenzyme of alkaline phosphatase (CAP) was evaluated as a screening test for hyperadrenocorticism (HAC) in dogs. A series of 40 dogs with HAC (CAP range, 96 to 14,872 U/L), 30 clinically normal dogs (CAP range, 0 to 38 U/L), and 80 dogs with various diseases (non-HAC) and without history of exogenous glucocorticoid exposure for a minimum of 60 days (CAP range, 0 to 1163 U/L) were used to evaluate the test. Sensitivity and specificity of CAP was calculated at various cutoff points for absolute CAP activity and for CAP activity expressed as a percentage of total alkaline phosphatase activity. A cutoff point of 90 U/L was selected as optimal for use of this assay as a screening test for HAC. A prevalence survey then was done of all canine serum samples submitted to our diagnostic laboratory over a 3-month period, to calculate the predictive values of a positive and a negative test result in a clinical population and to determine the relative frequency and magnitude of CAP activity in dogs that had received glucocorticoids. The predictive values of a positive and a negative test result at the 90 U/L cutoff value were 21.43% (95% confidence limits, 8.3 to 40.95%) and 100% (95% confidence limit > 96%), respectively. It was concluded that CAP isoenzyme activity, determined by routine biochemical analysis by an automated levamisole-inhibition assay, could function as a screening test for HAC; however, the predictive value of a positive test result was too low to recommend the assay as a diagnostic test.(ABSTRACT TRUNCATED AT 250 WORDS)     

Isoxazolylthioamides as potential immunosuppressants a combinatorial chemistry approach

A library of thioamide derivatives of leflunomide 1a and of its bioactive metabolite 1b has been synthesised on solid phase. Thus, para-substituted phenylacetic acids were coupled to TentaGel and were subsequently reacted with aromatic isothiocyanates. Treatment of the resulting enaminothioamides with hydroxylamine led to their simultaneous cyclisation and cleavage from the resin affording 2-25. Their in vitro profiling demonstrated that the amide-thioamide isologous substitution was detrimental of the biological activity.     

Total knee arthroplasty in patients receiving Workers' Compensation

The poor outcomes in patients who have a low-back injury that was sustained while they were on the job have been well described in many studies. The purpose of the current study was to determine the influence of Workers' Compensation on the outcome of total knee arthroplasty in forty-two patients who had been managed between January 1980 and December 1993. There were thirty-two men and ten women, and the mean age at the time of the operation was forty-eight years (range, twenty-nine to sixty-eight years). These patients were directly matched with a group of forty-two patients who were not receiving compensation. The two groups were matched with regard to nine parameters: age, gender, obesity index, preoperative deformity in the coronal plane, preoperative level of symptoms, preoperative radiographic severity according to the criteria of Ahlb?ck, method of fixation, number of previous procedures, and duration of follow-up. After a mean duration of follow-up of eighty months (range, forty-eight to 178 months), the patients who were receiving compensation had a mean Knee Society score of 64 points (range, 25 to 100 points). Twelve (29 per cent) of the patients in this group had an excellent or good clinical result, and thirty (71 per cent) had a fair or poor result or had had a revision. The patients who were not receiving compensation had a mean Knee Society score of 93 points (range, 57 to 100 points) after a similar duration of follow-up. Thirty-seven patients (88 per cent) in this group had an excellent or good clinical result, and five (12 per cent) had a fair or poor result or had had a revision; the difference between the two groups with regard to fair or poor results and revisions was significant (p < 0.01). With the numbers available, no significant differences could be detected between the two groups with regard to objective measurements of range of motion and stability or with regard to radiographic alignment, the presence of radiolucent lines, or the shedding of beads. On the basis of our findings, we believe that surgeons should be aware that Workers' Compensation is one of several variables that may have an untoward influence on the perceived outcome of total knee arthroplasty.     

Static forces on the anode wires in a straw chamber

This paper derives equations for the deflection of an anode wire in a proportional straw chamber under electrostatic forces due to misalignments of the wire, deformation of the straw tube surface, and gravity.     

Prevalence, risk factors, O serogroups, and virulence profiles of Shiga toxin-producing bacteria from cattle production environments

Shiga toxin (Stx)-producing bacteria are important human pathogens that have been linked with cattle and associated food products. We recovered Stx-producing bacteria from 27.5% of cattle, 6.8% of water, and 2.3% of wildlife samples from a cattle production area during an 11-month period. Positive samples were found during every month and on 98% of sampling days. We recovered isolates from all cattle operations sampled, and prevalence within operations ranged from approximately 5 to 33%. Cattle prevalence was associated with the presence of Stx-producing bacteria in water and the production group and environment of cattle, with an interaction between production group and environment. Odds of recovering isolates from cattle were highest for groups of adult cows and their unweaned calves in pasture environments. Overall, 49 O serogroups were identified from 527 isolates. Seventy of the isolates contained virulence genes that encoded intimin and enterohemorrhagic Escherichia coli hemolysin. These were serogroups O111, O157, O109, O103, O145, O172, O84, O26, O108, O117, O126, O159, O5, O69, O74, O98, and O-rough. Our results suggest that the prevalence of Stx-producing bacteria can be relatively high in cattle, and associated factors may not be entirely similar to those reported for serotype O157:H7. Although Stx-producing bacteria were frequently detected, the strains may not be equally pathogenic for humans given the wide variety of serogroups and virulence genes. However, focusing on O157:H7 in food safety and surveillance programs may allow other Stx-producing bacteria, which appear to be widespread in cattle, to go undetected.