Merging Data with Modeling: An Example from Fatigue.

It is well known that errors are inevitable in experimental observations, but it is equally unavoidable to eliminate errors in modeling the process leading to the experimental observations. If estimation and prediction are to be done with reasonable accuracy, the accumulated errors must be adequately managed. Research in fatigue is challenging because modeling can be quite complex. Furthermore, experimentation is time-consuming, which frequently yields limited data. Both of these exacerbate the magnitude of the potential error. The purpose of this paper is to demonstrate a procedure that combines modeling with independent experimental data to improve the estimation of the cumulative distribution function (cdf) for fatigue life. Subsequently, the effect of intrinsic error will be minimized. Herein, a simplified fatigue crack growth modeling is used. The data considered are a well-known collection of fatigue lives for an aluminum alloy. For lower applied stresses, the fatigue lives can range over an order of magnitude and up to 107 cycles. For larger applied stresses, the scatter in the lives is considerably reduced. Consequently, modeling must encompass a variety of conditions. The primary conclusion of the effort is that merging independent experimental data with a reasonably acceptable model vastly improves the accuracy of the calibrated cdfs for fatigue life, given the loading conditions. This allows for improved life estimation and prediction. For the aluminum data, the calibrated cdfs are shown to be quite good by using statistical goodness-of-fit tests, stress-life (S-N) analysis, and confidence bounds estimated using the mean square error (MSE) method. A short investigation into the effect of sample size is also included. Thus, the proposed methodology is warranted.

Impaired quality of life of adults with skin disease in primary care.

BACKGROUND: Although 75% of skin problems are managed exclusively in primary care, most information on the impact of skin disease on quality of life is hospital based. OBJECTIVES: To examine the ease of use of the Dermatology Life Quality Index (DLQI) in primary care and to measure the handicap levels found, analysed by skin disease, sex and age. METHODS: The handicap levels identified were compared with those published for patients with the same conditions attending hospital clinics. Some conditions that rarely present in secondary care were also studied. RESULT: S The overall mean +/- SD DLQI score was 7.37 +/- 5.71 (women 7.8 +/- 5.8, n = 196; men 6.8 +/- 5.6, n = 145). The scores for separate diseases were similar in ranking and only slightly lower than those in hospital-based studies. The possibility of bias towards surveying an unrepresentative sample of patients is discussed. There was no correlation between age and DLQI score. CONCLUSIONS: The DLQI proved easy to use in general practice. The impact of skin diseases on the quality of life of patients seen in primary care is comparable with that of patients seen in secondary care. This information could be used to inform the planning of services for these patients.

Salivary and gastric epidermal growth factor in patients with Zollinger-Ellison syndrome: its protective potential.

OBJECTIVE: Evidence is accumulating that epidermal growth factor (EGF) is a major molecule contributing to the maintenance of the integrity of the upper alimentary tract mucosa before and after injury by acid and pepsin. Patients with Zollinger-Ellison Syndrome (ZES) typically have hypersecretion of acid and pepsin; however, the concentration and rate of secretion of salivary and gastric EGF that could counteract these potentially aggressive factors are unknown. Accordingly, this study was conducted to determine whether EGF affords mucosal protection in ZES patients. METHODS: The concentration and output of salivary (sEGF) and gastric epidermal growth factor (gEGF) were measured in eight patients with ZES and the results compared to those in 17 patients with nonulcer dyspepsia (NUD), serving as a control group. All patients had normal esophageal and gastric mucosa as determined by endoscopy. Total saliva was collected during 1-h parafilm- and 1-h pentagastrin/parafilm-stimulated conditions, as well as basal and pentagastrin-stimulated gastric juice. The concentration and output of EGF were determined by radioimmunoassay. RESULTS: The concentration of EGF in saliva collected from ZES patients after parafilm chewing was significantly higher compared to that in NUD patients (4.61 +/- 0.59 vs 2.75 +/- 0.50 ng/ml, p < 0.05). The concentration of EGF in saliva collected after pentagastrin stimulation in ZES patients was also significantly higher than in NUD patients (4.37 +/- 0.73 vs 2.22 +/- 0.37 ng/ml, p < 0.05). Salivary EGF output during parafilm chewing in ZES and NUD were similar (68 +/- 6.4 vs 109 +/- 25.2 ng/h). Salivary EGF output after administration of pentagastrin in ZES and NUD was also similar (66 +/- 6.1 vs 132 +/- 45.4 ng/h). Basal EGF output in the gastric juice of patients with ZES was 3-fold higher than in patients with NUD (801 +/- 73 vs 271 +/- 32 ng/h, p < 0.01). Pentagastrin-stimulated EGF output was similar in both groups (705 +/- 92 vs 675 +/- 168 ng/h). CONCLUSIONS: Patients with ZES have a significantly higher EGF concentration in saliva and EGF output in basal gastric juice. This elevated content of salivary and gastric EGF in ZES patients may play a protective role in preventing the development of reflux esophagitis and gastric ulcer under the impact of gastric acid and pepsin hypersecretion.

Minocycline-induced discolouration of the sclerae.

We report two patients with minocycline-induced pigmentation of the sclerae. Cutaneous pigmentation is a well-recognized complication of minocycline therapy, but only five cases of pigmentation of the sclerae have been described previously. These five patients have a number of features in common with the two reported here. We propose that these patients represent the most severe end of the spectrum of minocycline-induced cutaneous changes. Patients should be warned about the possibility of the occurrence of pigmentary changes before starting therapy.

Effective measures for reducing blood loss from diagnostic laboratory tests in intensive care unit patients.

We studied ICU patient blood loss as a result of diagnostic testing (DBL) and the effect of two measures to reduce it. A policy of using small volumes (pediatric phlebotomy tubes, reduced syringe volumes) for the most frequent laboratory tests was implemented in our medical ICU. We prospectively studied 151 patients admitted during two consecutive 10-wk periods. During period 2, DBL was displayed on each ICU flow sheet. The DBL/day (43.6 +/- 3 [SEM] ml) was significantly lower (62.6 +/- 4 ml) than it would have been if standard volume tubes had been used. This represented an average savings of 33%. During period 1 (n = 81), eight (10%) patients with no diagnosis involving blood loss had a decrease in Hct and received transfusion. DBL was significantly higher (316 +/- 81 vs. 168 +/- 18 ml, p less than .001) for these patients and represented an average of 17% of transfusion requirements. During period 2 (n = 70), such transfusion requirements were significantly reduced (only one of 70, p less than .001), as were tests ordered/day (7.8 +/- 0.5 vs. 9.5 +/- 0.6, p less than .05). We conclude that DBL is a major health problem for the ICU patient. Routine use of small specimen volumes in this setting is warranted. Recording DBL for use in physician decision-making also significantly impacts this problem and should be considered an important part of the ICU database.

Quiet Zone Within a Seismic Gap near Western Nicaragua: Possible Location of a Future Large Earthquake.

A 5700-square-kilometer quiet zone occurs in the midst of the locations of more than 4000 earthquakes off the Pacific coast of Nicaragua. The region is indicated by the seismic gap technique to be a likely location for an earthquake of magnitude larger than 7. The quiet zone has existed since at least 1950; the last large earthquake originating from this area occurred in 1898 and was of magnitude 7.5. A rough estimate indicates that the magnitude of an earthquake rupturing the entire quiet zone could be as large as that of the 1898 event. It is not yet possible to forecast a time frame for the occurrence of such an earthquake in the quiet zone.