We use x-ray photon correlation spectroscopy (XPCS) to probe the dynamics of colloidal particles in polycrystalline ice. During freezing, the dendritic ice morphology and rejection of particles from the ice created regions of high particle density, where some of the colloids were forced into contact and formed disordered aggregates. The particles in these high density regions underwent ballisti...

The photoluminescence dynamics of colloidal CdSe/ZnS/streptavidin quantum dots were studied using time-resolved single-molecule spectroscopy. Statistical tests of the photon-counting data suggested that the simple "on/off" discrete state model is inconsistent with experimental results. Instead, a continuous emission state distribution model was found to be more appropriate. Autocorrelation anal...

Introduction: In the treatment of breast cancer, breast conserving surgery (BCS) and whole breast irradiation is a usual technique. The influence of lumpectomy boost following breast radiotherapy is apparent, but there are different delivery methods. This work intended to compare the dosimetric parameters of electron beams and photon beams for boosting irradiation in breast can...

A crystal design strategy is described that generates hexagonal-phased NaYF4 :Nd/Yb@NaYF4 :Yb/Tm luminescent nanocrystals with the ability to emit light at 803 nm when illuminated at 745 nm. This is accomplished by taking advantage of the large absorption cross-section of Nd(3+) between 720 and 760 nm plus efficient spatial energy transfer and migration through Nd(3+) →Yb(3+) →Yb(3+) →Tm(3+) . ...

A visible wide field multispectral system for comprehensive imaging of skin chromophores and blood vessels has been implemented, and an inhomogeneous Monte Carlo model of photon migration with randomly distributed blood vessels embedded in dermis has been developed. Predetermined nonlinear transforms have been obtained to address the nonlinear interdependent relationship among diffusive reflect...

the monte carlo method can be used to describe any technique that approximates solutions to quantitative problems through statistical sampling. this method is considered to be the most accurate method for dose calculation in radiotherapy. for complete modeling of a linear accelerator, it is required that the manufactured information covers all data, but some data such as primary electron energy...

We demonstrate a new approach for determining particle-size distribution in concentrated suspensions from spectral measurement of isotropic scattering coefficients by use of steady-state, continuous-wave photon-migration techniques. Successful recovery of particle-size distribution for TiO(2) suspensions in the form of log-normal functions is achieved through a regularized inverse algorithm, in...

We reconsider the problem of diffusion of particles at constant speed and present a generalization of the Telegrapher process to higher dimensional stochastic media (d > 1), where the particle can move along 2 d directions. We derive the equations for the probability density function using the " formulae of differentiation " of Shapiro and Loginov. The model is an advancement over similiar mode...

New preparations, fluorescent probes and imaging techniques are providing the means to observe the behavior of cells in the tissue environment of lymphoid organs. In particular, when combined with two-photon laser microscopy, intravital imaging of surgically exposed lymph nodes provides a unique view of lymphocyte migration and antigen presentation as it occurs within the living animal. The vie...