size reduction of high energy materials such as 1, 3, 5, 7-tetranitro- 1, 3, 5, 7-tetraaza cyclooctane (hmx) has considerable influences on improving their explosive characteristics. in this study, nanosized hmx par­ticles were produced using ultrasonically reprecipitation method by applying water as a safe and accessible antisolvent instead of unsafe conventional methods. sem photographs revea...

the influence of mo particle size on the catalytic activity and product selectivity of alkalized mos2 nanocatalysts has been investigated. nanocatalysts are prepared using a microemulsion technique with water-to-surfactant ratios of 1-12. three different techniques, including xrd, tem, and hydrogen chemisorption were used to determine the molybdenum average particle size and their activity and ...

Sample-size determination is often an important step in planning a statistical study—and it is usually a difficult one. Among the important hurdles to be surpassed, one must obtain an estimate of one or more error variances, and specify an effect size of importance. There is the temptation to take some shortcuts. This paper offers some suggestions for successful and meaningful sample-size deter...

using size at first maturity (sfm) as a biological reference point, the minimum legal size (mls) for the black clam, villorita cyprinoides was fixed at 20 mm. corresponding minimum legal weight was calculated as 3.4 g. the reproductive load and mean generation time were determined as 0.35 and 0.72, respectively. of the total quantity of clams exploited during 1996-97, 50% were juveniles. the pe...

network scale-up is an indirect method for estimating the size of hidden, hard-to-count or high risk populations. social network size estimation is the first step in this method. the present study was conducted with the purpose of estimating the social network size of the tehran province residents and its determinants.maximum likelihood estimation was applied to estimate people's network sizes ...

optimum sample size is an essential component of any research. the main purpose of the sample size calculation is to determine the enough number of units needed to detect the unknown clinical parameters or the treatment effects or the association after data gathering. it is not uncommon for studies to be underpowered and failing to detect the existed treatment effects due to inadequate sample s...

A sample size calculation for logistic regression involves complicated formulae. This paper suggests use of sample size formulae for comparing means or for comparing proportions in order to calculate the required sample size for a simple logistic regression model. One can then adjust the required sample size for a multiple logistic regression model by a variance inflation factor. This method re...

As the sizes of food packages and portions have changed rapidly over the past decades, it has become crucial to understand how consumers perceive and respond to changes in size. Existing evidence suggests that consumers make errors when visually estimating package and portion sizes, and these errors significantly influence subsequent food choices and intake. We outline four visual biases (arisi...

Exact power and sample size calculation for bioequivalence studies with high order crossover designs using statistical software nQuery are presented. Such calculation can be very easily performed, and thus provides a convenient tool for practical usage.