the statistical analysis of spatial data is usually done under gaussian assumption for the underlying random field model. when this assumption is not satisfied, block bootstrap methods can be used to analyze spatial data. one of the crucial problems in this setting is specifying the block sizes. in this paper, we present asymptotic optimal block size for separate block bootstrap to estimate the...

background: in radiotherapy, wedge filters are used for optimizing the tumor dose distribution in patients. the attenuation in beam intensity due to the presence of wedge filter is compensated by means of a wedge factor measured at the central axis of the beam. the field size, depth and ssd dependence of wedge factor have been assessed for 9mv radiations of neptun pc linear accelerator. materia...

The single-hole collimator limits the field of view of a scintillation probe to a single organ. The sensitivity for counting is approximately equal over the entire field of view. The most common use of this collimator is for iodine uptake measurements of the thyroid. An example of this "flat-field collimator" is shown (Fig. I). The sensitivity profile at the working distance illustrates the rel...

This paper provides steady state queue-size distribution for a G/G/1 queue by using principle of maximum entropy. For this purpose we have used average queue length and normalizing condition as constraints to derive queue-size distribution. Our results give good approximation as demonstrated by taking a numerical illustration. In particular case when square coefficient of variation of inter-arr...

We have synthesized a new tetranuclear manganese cluster with a distorted cubanelike [Mn4O4]-core. High field magnetization experiments reveal an intramolecular antiferromagnetic coupling between the four manganese ions. We explain our results both qualitatively and quantitatively by a simple spin square model in terms of four equal antiferromagnetic exchange interactions in the core with coupl...

A new method for calculating the stress field in bounded ice shelves is used to compare strain rate and deviatoric stress on the Ross Ice Shelf, Antarctica. The analysis shows that strain rate (per second) increases as the third power of deviatoric stress (in newtons per square meter), with a constant of proportionality equal to 2.3 x 10(-25).

background: attenuation coefficient (μ) plays an important role in calculations of treatment planning systems, as well as determination of dose distributions in external beam therapy, dosimetry, protection, phantom materials and industry. so, its exact measurement or calculation is very important. the aim of this study was to evaluate the μ in different points in the water phantom analytically ...

In this work, we calculate the limit distribution of the total cost incurred by splitting a tree selected at random from the set of all finite free trees. This total cost is considered to be an additive functional induced by a toll equal to the square of the size of tree. The main tools used are the recent results connecting the asymptotics of generating functions with the asymptotics of...