Large-scale simulation studies in image pattern recognition

Many obstacles to progress in image pattern recognition result from the fact that per-class distributions are often too irregular to be well-approximated by simple analytical functions. Simulation studies offer one way to circumvent these obstacles. We present three closely related studies of machine-printed character recognition that rely on synthetic data generated pseudo-randomly in accordance with an explicit stochastic model of document image degradations. The unusually large scale of experiments - involving several million samples that makes this methodology possible have allowed us to compute sharp estimates of the intrinsic difficulty (Bayes risk) of concrete image recognition problems, as well as the asymptotic accuracy and domain of competency of classifiers     

Training in firearm safety counseling in family practice residency programs

We have studied the function of partial orthotopic liver transplantation in the rat by evaluating prothrombin time (PT), liver blood flow, basal and glucose-stimulated insulin secretion and glucose tolerance, and the reticuloendothelial function (RES) in hepatectomized rats subjected to partial liver transplantation. A graft corresponding to 68% of a normal liver was transplanted to totally hepatectomized rats. Comparison was made between control rats and rats subjected to 32% liver resection. PT was not significantly different in the transplanted group compared with liver-resected and control rats. Laser Doppler flowmetry showed that at 28 days after surgery, blood flow had increased in the transplanted livers. Furthermore, on the third day after transplantation, basal plasma insulin was increased and the plasma insulin response to glucose was exaggerated, suggesting reduced insulin action and impaired insulin degradation. Finally, uptake of radioactive-labeled E. coli bacteria, as a measure of RES function, was not compromised in transplanted animals. Based on these results, we conclude that reduced-size liver transplant in out-bred rats results in fast normalization of liver function after surgery although, immediately after surgery, glucose intolerance is seen.     

Relation between sexual abuse in childhood and adult depression: case-control study

OBJECTIVE: To examine the association between sexual abuse in childhood and adult depression in women. DESIGN: Two stage, case detection and case identification design, using the 30-item general health questionnaire and the Beck depression inventory for screening and the affective items relating to current functioning on the schizophrenia and affective disorders schedule to identify depressed cases. Details of sexual abuse in childhood were elicited retrospectively by semistructured interview, and social problems by the social problems questionnaire. SETTING: Three general practices, in middle class suburban, deprived inner city, and rural areas. SUBJECTS: 1189 women were screened and 237 subsequently interviewed; 132 were depressed. RESULTS: 49 (37%) of the depressed interviews and 24 (23%) of the non-depressed interviews reported experience of sexual abuse when they were aged under 16 years. A positive association existed between the more severe abuse and depression--all those who had experienced penetration were depressed as adults. A relation was also found between sexual abuse in childhood and sexual problems, housing problems, and problems with their children at school. CONCLUSION: A positive association between child sexual abuse and depression was confirmed, but this was confined to more severe abuse (penetration or attempted penetration).     

Changes in medical stability upon admission to a rehabilitation unit

The implementation of Medicare's prospective payment system in acute care has coincided with a steady increase in medically unstable admissions to our freestanding rehabilitation facility. We investigated the consequences of these admissions by collecting medical information regarding transfers beginning in 1983. Patients requiring transfer back to the acute setting within 1 day of admission were considered medically unstable and their charts were reviewed. The number of patients requiring transfer back within 1 day increased from 1.5% of all first admissions to 3.1% in 1988 (Mantel - Haenszel chi 2 = 8.03, (df = 1), p < .01), but the increase among Medicare patients alone was not significant. This progressive increase was most pronounced in the cerebrovascular accident and spinal cord injury populations. Beginning in 1988, an intensified preadmission evaluation program was implemented, resulting in a significant decline in unstable patient transfers from hospitals where our consultants were on staff. Physiatric consultations at referral institutions decreased the number of unstable patients at admission.     

Family practice physicians' firearm safety counseling beliefs and behaviors

The purpose of this study was to identify family physicians' firearm safety counseling beliefs and behaviors. A survey was mailed to a random sample of 600 members of the American Academy of Family Physicians. A three wave mailing technique was used to maximize the response rate and yielded 271 usable surveys (55% response rate). Outcome measures included training experience in firearm safety counseling, the prevalence of firearm safety counseling by family physicians, and their perceptions regarding such counseling. The majority (78%) of family physicians lacked formal training on how to counsel patients about firearm safety and 49% believed more time should be spent in residency programs on firearm safety counseling. The majority (84%) of respondents never or rarely counseled patients on firearm safety and 50% believed firearm safety counseling should be a low priority in their delivery of primary care. The majority of respondents did not regularly counsel patients about firearm safety, did not believe firearm safety counseling should be a priority, and did not believe firearm safety counseling would be effective in reducing firearm-related trauma.     

Laser scattering instrument for real time in-vivo measurement of ciliary activity in human fallopian tubes

Based on a laser light scattering technique and fibre optic probe, we have developed and tested a simple and practical device for real time measurements of ciliary activity in human Fallopian tubes during laparoscopy and laparotomy. A further aim was to investigate the relationship between the ciliary beat frequency (CBF) and the morphology of the ciliary epithelium. The mean +/- SE of CBF in the fimbria and in the ampulla were 5.4 +/- 0.3 Hz and 5.0 +/- 0.1 Hz respectively. Small pieces of fimbria and ampulla epithelium were taken from the same sites at which the CBF was measured, and the percentage of ciliary cells was determined by scanning electron microscopy. A high positive correlation was found between CBF and the percentage of ciliary cells in the fimbria (r = 0.84) and in the ampulla (r = 0.88). The instrument presented in this study provided, for the first time, a quantitative examination of the CBF in intact human Fallopian tubes and may be used for the investigation of ciliary activity in patients with infertility.     

Curvilinear fatigue crack reliability analysis by stochastic boundary element method

In this paper, the stochastic boundary element method, which combines the mixed boundary integral equations method explored in Reference 1 with the first-order reliability method, is developed to study probabilistic fatigue crack growth. Due to the high degree of complexity and non-linearity of the response, direct differentiation coupied with the response-surface method is employed to determine the response gradient. Three random processes, the mode I and mode II. stress intensity factors and the crack direction angle, are included in the expression of the response gradient. The sensitivity of these random processes is determined using a first-order response model. An iteration scheme based on the HL-RF method² is applied to locate the most probable failure point on the limit-state surface. The accuracy and efficiency of the stochastic boundary element method are evaluated by comparing the cumulative distribution function of the fatigue life obtained with Monte Carlo simulation. The reliability index and the corresponding probability of failure are calculated for a fatigue crack growth problem with randomness in the crack geometry, defect geometry, fatigue parameters and external loads. The response sensitivity of each primary random variable at the design point is determined to show its role in the fatigue failure. The variation of each primary random variable at the design point with the change of probability of failure is also presented in numerical examples.     

Tight bounds on Rician-type error probabilities and someapplications

Consider the classic problem of evaluating the probability that one Rician random variable exceeds another, possibly correlated, Rician random variable. This probability is given by Stein (1964) in terms of the Marcum's Q-function, which requires numerical integration on the computer for its evaluation. To facilitate application in many digital communication problems, we derive here tight upper and lower bounds on this probability. The bounds are motivated by a classic result in communication theory, namely, the error probability performance of binary orthogonal signaling over the Gaussian channel with unknown carrier phase. Various applications of the bounds are reported, including the evaluation of the bit error probabilities of MDPSK and MPSK with differential detection and generalized differential detection, respectively. The bounds prove to be tight in all cases. Further applications will be reported in the future