due to their widespread availability, sandstones are commonly used as a natural stone for buildings, monuments and sculptures. in thecurrent study, nine sandstone samples from the upper red formation (specified by the letters a, b, c, cg, s, s1, sh, tr and min)were studied from a petrophysical point of view and their durability was evaluated. then, their suitability as building stones wasassess...

background sleep apnea (sa) is a common sleep disorder among us adults. associations of sa with alcohol consumption and some chronic diseases have been inconsistent. objectives this study aimed to estimate prevalence of sa and examine its associations with potential factors including alcohol consumption, asthma, diabetes, and hypertension. patients and methods this was a cross-sectional study o...

In this experiment, wheat plants were exposed to drought stress during seed development then we worked on the obtained seeds. The seed mitochondrial ultra-structure, and antioxidant enzymes in seedling were investigated after exposure to seed accelerated ageing. Drought stress during seed development induced some changes in mitochondrial ultra-structure. Encountering seed development to drought...

fifty-four specimens of the kingsoldier bream, argyrops spinifer (forsskal, 1775) from coastal waters of the persian gulf, in bushehr province, were aged by otolith readings to assess the suitability of using otolith length/weight for age estimation in this fish. otolith length and weight increased along with an increase in length and age of the fish. the relationship between fish length (tl) a...

we propose to use a mathematical method based on stochastic comparisons of markov chains in order to derive performance indice bounds‎. ‎the main goal of this paper is to investigate various monotonicity properties of a single server retrial queue with first-come-first-served (fcfs) orbit and general retrial times using the stochastic ordering techniques‎.

in this paper, we present a genetic algorithm (ga) for optimization of a multi-mode resource constrained time cost trade off (mrctct) problem. the proposed ga, each activity has several operational modes and each mode identifies a possible executive time and cost of the activity. beyond earlier studies on time-cost trade-off problem, in mrctct problem, resource requirements of each execution mo...

given a set  of  points in the plane and a constant ,-center problem is to find two closed disks which each covers the whole , the diameter of the bigger one is minimized, and the distance of the two centers is at least . constrained -center problem is the -center problem in which the centers are forced to lie on a given line . in this paper, we first introduce -center problem and its constrain...

Planktonic copepods are a key group in the marine pelagic ecosystem, linking primary production with upper trophic levels. Their abundance and population dynamics are constrained by the life history tradeoffs associated with resource availability, reproduction and predation pressure. The tradeoffs associated with the ageing process and its underlying biological mechanisms are, however, poorly k...

Atrial fibrillation (AF) is the most common cardiac arrhythmia, its prevalence increasing markedly with age. Atrial fibrillation is strongly associated with increased risk of morbidity, including stroke and thromboembolism. There is growing awareness of the economic burden of AF due to ageing populations and constrained public finances. A systematic review was performed (1990-2009). Cost studie...