We have undertaken the task to calculate, by means of extensive numerical simulations and by different procedures, the cluster fractal dimension (d f ) of colloidal aggregates at different initial colloid concentrations. Our first approach consists in obtaining d f from the slope of the log-log plots of the radius of gyration versus size of all the clusters formed during the aggregation time. I...

A multi-scale model is proposed to investigate functionally graded (exponential or power-law grading in the radial direction) hollow cylinders (discs), with fibers, particles, or disc-shaped reinforcements, subjected to harmonic loading conditions. The stress analyses are performed by dividing the cylinders (discs) into several layers each with homogeneous properties, which are functionally gra...

In this paper, an exact analytical solution for free vibration of rotating bi-layered cylindrical shell composed of two independent functionally graded layers was presented. The thicknesses of the shell layers were assumed to be equal and constant. The material properties of the constituents of bi-layered FGM cylindrical shell were graded in the thickness direction of the layers of the shell ac...

Photo-thermo-refractive (PTR) glass is a multicomponent photosensitive silicate glass that, after successive UV-exposure and thermal treatment, exhibits a refractive index change that results from the precipitation of nano-crystalline NaF. This glass is successfully used for the fabrication of holographic optical elements (volume Bragg gratings) that dramatically enhance properties of numerous ...

1. Murray’s law states that the hydraulic conductance per blood volume of the cardiovascular system is maximized when the sum of the vessel radii cubed ( Σ r 3 ) is conserved. 2. We hypothesize that Murray’s law will apply to xylem conduits as long as they only transport water and do not also help support the plant. Specifically, the less volume of wood occupied by conduits, the more the condui...

We present an analysis of early Burst Alert Telescope and X-ray Telescope data for 107 gamma-ray bursts (GRBs) observed by the Swift satellite. We use these data to examine the behaviour of the X-ray light curve and propose a classification scheme for GRBs based on this behaviour. As found for previous smaller samples, the earliest X-ray light curve can be well described by an exponential, whic...

BACKGROUND Despite the common experience that interrupted sleep has a negative impact on waking function, the features of human sleep-wake architecture that best distinguish sleep continuity versus fragmentation remain elusive. In this regard, there is growing interest in characterizing sleep architecture using models of the temporal dynamics of sleep-wake stage transitions. In humans and other...

Single-junction microcrystalline silicon c-Si:H solar cells of selected i-layer crystalline volume fractions were light soaked AM1.5, 1000 h at 50 °C and subsequently annealed at increasing temperatures. The variations of subbandgap absorption during light soaking and during thermal annealing were monitored by Fourier transform photocurrent spectroscopy. The kinetics were shown to follow stretc...

The standard linear-quadratic survival model for radiotherapy is used to investigate different schedules of radiation treatment planning to study how these may be affected by different tumour repopulation kinetics between treatments. The laws for tumour cell repopulation include the logistic and Gompertz models and this extends the work of Wheldon et al (1977 Br. J. Radiol. 50 681), which was c...