We consider visibility graphs involving bars and arcs in which lines of sight can pass through at most k objects. We prove a new edge bound for arc k-visibility graphs, provide maximal constructions for arc visibility graphs and semi-arc k-visibility graphs, and give a complete characterization of semi-arc visibility graphs. We further show that the family of arc i-visibility graphs is never co...

We analyze the behavior of a fragile material reinforced by a reticulated elastic unbreakable structure in the case of antiplane shear. The microscopic geometry of this material is described by means of two small parameters: the period ε of the grid and the ratio δ between the thickness of the fibers and the period ε. We show that the asymptotic behavior as ε → 0 and δ → 0 depends dramatically ...

purpose: to compare thickness of central cornea measured using pentacam, orbscan ii, and ultrasound pachymeter methods: patients with no history of corneal diseases or systemic diseases affecting eyes, who did not wear contact lens or use eye medications, and who with no previous history of corneal surgery were selected for this study. central corneal thickness (cct) was measured by three metho...

introduction: based on the invasive studies it has been shown that factors such as age, the progress of eye disorders, lens fibers compression and the biochemical changes of ocular matrix alter the physical characteristics and elastic properties of eye. in this study, a noninvasive method of estimating human eye elasticityis proposed and its relation with age and gender is evaluated using ultra...

purpose: to evaluate the effects of smoking on the central corneal thickness (cct). methods: in a historical chohort analytic study, referred cases have been divided into two groups (cigarette smokers, and non–cigarette smokers).  laboratory tests including fasting blood sugar (fbs), blood urea nitrogen (bun); and blood pressure were checked. complete eye examination was performed. cct was meas...

conclusions la increases the risk of cva and dementia. the la pathology is unknown. the epidemiological studies revealed the age, diabetes, smoking and atherosclerosis are related with la. our findings showed that cimt as an atherosclerosis marker was higher in la patients than control group. results totally 200 patients were studied, 102 in normal group and 98 in ila group. the mean age of pat...

objective: to assess follicular development and endometrial growth using transvaginal sonography in spontaneous and clomiphene citrate induced (cc) cycles. materials and methods: one hundred consecutive couples with unexplained infertility were recruited for this cross sectional study from 2003 to 2005. patients were monitored for the first cycle with no medication while the laboratory routine ...

background: sildenafil citrate may increase endometrial thickness and affect the outcome of frozen-thawed embryo transfer cycles. objective: the aim of this study was to estimate the effect of sildenafil citrate on ultrasonographic endometrial thickness and pattern and to investigate the estrogen level on the day of progesterone administration, the implantation rate and chemical pregnancy rate ...

In his discussion of Cox's (1972) paper on proportional hazards regression, Breslow (1972) provided the maximum likelihood estimator for the cumulative baseline hazard function. This estimator is commonly used in practice. The estimator has also been highly valuable in the further development of Cox regression and semiparametric inference with censored data. The present paper describes the Bres...