Errors in two-point sound reproduction.

This paper deals with the problem of reproducing two signals at two points in space by using two acoustic sources. While much is now known about the techniques available for the design of matrices of inverse filters that enable this objective to be achieved in practice, it is still the basic physics of the sound field produced that controls the effectiveness of such systems and which ultimately dictates their design. The basic physical processes involved in producing the cross-talk cancellation that enables the reproduction of the desired signals is revisited here by using a simple two source/two field point free field model. The singular value decomposition is used to identify those frequencies where the inversion problem becomes ill-conditioned and to explain physically the origin of the ill-conditioning. As observed previously, it is found that cross-talk cancellation becomes problematic when the path length difference between the two sources and one of the field points becomes equal to one half the acoustic wavelength. The ill-conditioned frequencies are also found to be associated with a limited spatial region of cross-talk cancellation and with large source outputs manifested in the time domain by responses of long duration.

Calciphylaxis causing necrotizing mastitis: a case report.

Calciphylaxis is a rare condition most commonly related to ESRD and hyperparathyroidism. We report a case of necrotizing mastitis caused by calciphylaxis following routine breast biopsy for microcalcifications. Early recognition of the potential for this condition should help in clinical management of patients with calciphylaxis.

Initial experience with soft-copy display of computed radiography images on three picture archive and communication systems.

We recently installed picture archive and communication systems (PACS) from three different vendors on our campus for evaluation. A major part of this evaluation involved assessing the capabilities of these systems for displaying computed radiography (CR) images for primary interpretation. The three PACS provided different functionality for CR image display in terms of availability of the proprietary Fuji CR image processing algorithms, availability of user-specified contrast look-up tables, and application of the processing at the time of CR image capture or image display. We found that the Fuji processing algorithms were important for printing film, but were not necessary for acceptable soft-copy display. Non-linear contrast processing produced superior results compared to simple linear processing (via standard window width and level controls). Display processing was best applied immediately prior to the display operation, as opposed to at the image capture time. This allows the display to be adjusted to demonstrate the full 10-bit range of the CR image, and also allows raw CR data (i.e. not optimized for any particular display device) to be stored in the long-term archive.

Oral ivermectin paste for the treatment of chorioptic mange in horses.

A single blind controlled clinical trial of oral ivermectin paste at a dose rate of 0.1 mg/kg daily for seven days for the treatment of chorioptic mange in horses was carried out. There was a statistically significant reduction in the numbers of mites in the samples taken from the treated horses compared with the untreated horses, but the mites were not eliminated from all the treated animals. Two further groups of horses were treated, one at a dose rate of 0.1 mg/kg daily for 10 days and the other with two doses of 0.2 mg/kg given two weeks apart. There were no statistically significant differences between any of the three treatment groups, and none of the treatments eliminated mites from all the treated horses.

Comparison of two shampoos for treatment of Malassezia pachydermatis-associated seborrhoeic dermatitis in basset hounds.

A randomised-double-blind parallel study compared the clinical and antimicrobial efficacies of a miconazole-chlorhexidine shampoo with a selenium sulphide shampoo for the treatment of seborrhoeic dermatitis associated with Malassezia pachydermatis in 33 basset hounds. All 16 miconazole-chlorhexidine treated hounds and 11 of 17 selenium sulphide treated hounds improved when shampooed at three-day intervals for three weeks. The miconazole-chlorhexidine treated hounds showed significantly greater reductions in pruritus (P < 0.01), erythema (P < 0.001), exudation (P < 0.01) and overall severity (P < 0.001), and in counts of M pachydermatis (P < 0.001), total bacteria (P < 0.001) and coagulase-positive staphylococci (P < 0.001), when compared to the selenium sulphide treated group. Improvements in scaling and coat condition did not vary significantly between the two groups. These results indicate that seborrhoeic dermatitis in basset hounds is often associated with elevated cutaneous populations of M pachydermatis and bacteria, and that the miconazole-chlorhexidine shampoo is more effective than the selenium sulphide product for the treatment for this disease.

Cost and efficacy of extracorporeal shock wave lithotripsy versus ureteroscopy in the treatment of lower ureteral calculi.

We retrospectively reviewed the extracorporeal shock wave lithotripsy (ESWL) and ureteroscopy experience relative to cost and efficacy of a group of practitioners skilled in the use of both procedures for the treatment of lower ureteral stones. Although the initial success rate was higher with ureteroscopy, no significant difference could be found in final success or complication rates. The cost of ESWL was approximately 60% higher than that for ureteroscopy (mean $7,320.26 versus $4,568.47, p less than 0.005). Given the current restraints on resources, and the equal efficacy and morbidity of both procedures, ureteroscopy must be considered the procedure of choice in the management of lower ureteral stones.

Plain film reporting in the UK.

A survey has been carried out to investigate the extent of non-reporting and delayed reporting of plain radiographs in UK hospitals. The survey took the form of a confidential postal questionnaire to all consultant radiologists in the UK. Five hundred and sixty-five replies were included in the study, representing 45% of the total consultant workforce. The majority of respondents (58%) indicated their belief that all plain films should be reported by a radiologist. However, only 16% stated that all films were reported, and 22% stated that more than 10% of films were never reported. The principal categories of films not reported were: out of date, dental, fracture clinic follow-up and orthopaedic out-patients. The commonest reason given for non-reporting was the near certainty that the report would be too late to influence clinical management. Although such a survey cannot be used to estimate precise prevalence, it does show that large numbers of radiological examinations go unreported, or are reported after the films have been returned from the referring clinician. The level of non-reporting is at variance with the stated ideals of the majority of radiologists questioned. Further research is needed to establish the clinical importance of present levels of non-reporting and delayed reporting.

Psychologic health of women: a phenomenologic study of women's inner strength.

This article describes a phenomenologic research study of psychologic health--the inner strength of women. The research objective was to identify and to describe the meanings, qualities, and structures of the lived experiences of inner strength for women. Nine women were selected who acknowledged and articulated their subjective experience of inner strength. Data were generated using unstructured, in-depth, face-to-face interviews. Data analysis incorporated the methods of Colaizzi, van Manen, and Spiegelberg. The results revealed nine essential themes that add to the cumulative knowledge base of psychologic health by generating new meanings of the nature and essences of inner strength from female perspectives.

Bladder carcinoma treated by partial cystectomy: a review of 54 cases.

A retrospective study of 54 partial cystectomies done between 1958 and 1973 was undertaken to evaluate the proper role of the procedure in the treatment of bladder carcinoma. The operative mortality rate was 1.8% and the postoperative morbidity was low in the series. The 5-year survival rate for stages B1 (21 cases) and B2 (16 cases) lesions was 57%, with an over-all 5-year survival rate for all stages of 48%. Indications for the operation are presented and factors influencing survival are discussed.

Gastric bezoars--spontaneous resolution.

Six cases of gastric phytobezoars were seen on fiberoptic gastroscopy over a period of four years during which time 1,400 gastroscopies were done. Four of these cases showed complete resolution of bezoars on repeat endoscopy during a follow-up period ranging from two weeks to one year. Our experience shows that, in the absence of gastric outlet obstruction, small bowel obstruction or other serious problems due to bezoars, they may not need surgical or aggressive medical treatment.