By assuming a Boltzmann distribution for the molecular equilibrium between local and bulk environments, a general model is derived for the prediction of coordination numbers and local compositions of square-well and square-shoulder fluids. The model has no empirical parameter fitted from the data of square-well and square-shoulder fluids, but is valid from the low-density limit to the high-dens...

Nowadays MOSFET dosimeters are widely used for dose verification in radiotherapy procedures. Although their sensitive area satisfies size requirements for small field dosimetry, their use in radiosurgery has rarely been reported. The aim of this study is to propose and optimize a calibration method to perform surface measurements in 6 MV shaped-beam radiosurgery for field sizes down to 18 × 18 ...

We study the problem embedding an n-point metric space into another n-point metric space while minimizing distortion. We show that there is no polynomial time algorithm to approximate the minimum distortion within a factor of Ω((log n)1/4−δ) for any constant δ > 0, unless NP ⊆ DTIME(n ). We give a simple reduction from the METRIC LABELING problem which was shown to be inapproximable by Chuzhoy ...

Development and homeostasis require repeated symmetric cell divisions, which in turn depend on a centered mitotic spindle. In this issue, Kiyomitsu and Cheeseman uncover two mechanisms that ensure correct spindle positioning in anaphase: cortical dynein for pulling the spindle to the cell center and asymmetric membrane elongation that adjusts the position of the cell center to the cleavage plane.

Division subdivides mass without increasing it. So one should not expect that an increase in cell division would make an organism bigger. Both classic and recent experiments confirm this simple rationale: altering proliferation produces normally sized body structures with either especially small or exceptionally large cells.

In the present work, we investigated the accuracy of the electron pencil-beam redefinition algorithm (PBRA) in calculating central-axis percent depth dose in water for rectangular fields. The PBRA energy correction factor C(E) was determined so that PBRA-calculated percent depth dose best matched the percent depth dose measured in water. The hypothesis tested was that a method can be implemente...

Purpose: To investigate the energy dependence/spectral sensitivity of silicon diodes designed for small-field dosimetry and obtain response factors (RFs) for arbitrary photon spectra using Monte Carlo (MC) simulations.   Methods: The EGSnrc user-code DOSRZnrc was used to calculate the dose deposition in water and in the active volume of a stereotactic diode f...

This paper proposes a new sieving algorithm that employs a bucket sort as a part of a factoring algorithm such as the number field sieve. The sieving step requires an enormous number of memory updates; however, these updates usually cause cache hit misses. The proposed algorithm dramatically reduces the number of cache hit misses when the size of the sieving region is roughly less than the squa...