Ultrasonic Characterization of Horizontal Density Variations in Oriented Strandboard

Random flake deposition in mat forming of oriented strandboard (OSB) results in inherent horizontal density variation that affects the panel strength quality. In this paper, a silicon gel coupled ultrasonic transmission (UT) was used to locate, map, and validate the horizontal density distribution in laboratory-made OSB. Two test boards were manufactured at each of three nominal density (ND) and three resin content (RC) levels. The UT variables velocity, attenuation, and root mean square voltage formed excellent complementary predictors of density for all RC and panel types. Based on the allowable ±10% variation in the average measured densities, both the general and polynomial models provided improved density prediction for boards at higher RC and ND levels. Using the contour and out-of-limits plots, the predicted horizontal densities gave a reasonable spatial approximation to the measured densities. All 6% RC panels with densities of 0.60 g/cm3 or greater conformed well to the limits, with declining conformity towards the lower RC panels

Fitting Weibull and Lognormal Distributions to Medium-Density Fiberboard Fiber and Wood Particle Length

Fiber lengths were analyzed for random samples of medium-density fiberboard (MDF) fibers and wood particles taken from eleven different populations. For six of the samples, the lognormal distribution fit the data, while the Weibull distribution did not. For three of the samples, the Weibull fit the data, while the lognormal did not. For two of the samples, both the lognormal and Weibull fit the data. Conclusions were based on hypothesis tests imposing a bound of 0.05 on the probability of making a Type I error for each test. Tests were based on large sample 95% nonparametric simultaneous confidence bands for the underlying cumulative distribution functions of the data

Reply: Contrasting Split Plot And Repeated Measures Experiments And Analyses

The terms split plot and repeated measures are used by many authors throughout the statistical literature. However, the former is not used in a consistent manner, since many authors use this term in reference to inherently different experimental situations, each requiring a different analysis. Conversely, quite often inherently different experiments share a common analysis, as is the case with some types of split-plot and repeated measures experiments. Four distinct analyses are employed by various authors when describing split plot and repeated measures experiments in the classic literature. Four linear models, accounting for the four analyses, are stated in this article. Detailed examples are given that illustrate the relationships between experimental setup, model specification, and subsequent analysis

The role of bowel preparation in colorectal surgery: Results of the 2012-2015 ACS-NSQIP data

To analyze potential benefits with regards to infectious complications with combined use of mechanical bowel preparation (MBP) and ABP in elective colorectal resections.Despite recent literature suggesting that MBP does not reduce infection rate, it still is commonly used. The use of oral antibiotic bowel preparation (ABP) has been practiced for decades but its use is also controversial.Patients undergoing elective colorectal resection in the 2012 to 2015 American College of Surgeons National Surgical Quality Improvement Program cohorts were selected. Doubly robust propensity score-adjusted multivariable regression was conducted for infectious and other postoperative complications.A total of 27,804 subjects were analyzed; 5471 (23.46%) received no preparation, 7617 (32.67%) received MBP only, 1374 (5.89%) received ABP only, and 8855 (37.98%) received both preparations. Compared to patients receiving no preparation, those receiving dual preparation had less surgical site infection (SSI) [odds ratio (OR) = 0.39, P < 0.001], organ space infection (OR = 0.56, P ≤ 0.001), wound dehiscence (OR = 0.43, P = 0.001), and anastomotic leak (OR = 0.53, P < 0.001). ABP alone compared to no prep resulted in significantly lower rates of surgical site infection (OR = 0.63, P = 0.001), organ space infection (OR = 0.59, P = 0.005), anastomotic leak (OR = 0.53, P = 0.002). MBP showed no significant benefit to infectious complications when used as monotherapy.Combined MBP/ABP results in significantly lower rates of SSI, organ space infection, wound dehiscence, and anastomotic leak than no preparation and a lower rate of SSI than ABP alone. Combined bowel preparation significantly reduces the rates of infectious complications in colon and rectal procedures without increased risk of Clostridium difficile infection. For patients undergoing elective colon or rectal resection we recommend bowel preparation with both mechanical agents and oral antibiotics whenever feasible