The purpose of the Local Effect Model (LEM) is to calculate the dose dependent relative biological effectiveness (RBE) of charged particle radiation with respect to conventional photon radiation [1]. Because of computation time reasons, this is done within a low fluence approximation where the biological damage of a radiation field at arbitrarily high irradiation fluence is deduced from the dos...

We have analyzed the evolution of the spectral hardness parameter, Epk (the maximum of the νFν spectrum) as a function of fluence in gamma-ray bursts. We fit 41 pulses within 26 bursts with the trend reported by Liang & Kargatis (1996) which found that Epk decays exponentially with respect to photon fluence Φ(t). We also fit these pulses with a slight modification of this trend, where Epk decay...

Purpose: The purpose of this study is to develop an alternate empirical approach to estimate near-infra-red (NIR) photonpropagation and quantify optically induced drug release in brain metastasis, without relying on computationallyexpensive Monte Carlo techniques (gold standard). Targeted drug delivery with optically induced drug release is a non-invasive means to treat cancers and ...

We present a powerful experimental tool and analysis for characterization of two-photon absorption (2PA) spectra. We demonstrate this method with ZnS and then apply it to organic dyes in solution. We also compare the results with those from other methods such as two-photon fluorescence spectroscopy. This femtosecond pump-probe method uses a white-light continuum (WLC) as the probe to produce a ...

Time-resolved two-photon photoemission is applied to investigate electron dynamics in multiple monolayers (MLs) of ordered fullerite on a copper substrate. The experimental data are analyzed assuming coupled excited state dynamics. Rate equations fitted to these dynamics yield lifetimes of about 80 ps for the lowest unoccupied molecular orbital (LUMO), about 1.2 ns for the singlet exciton and 2...

It has been recognized for more than a century that chloroplasts alter their distribution within cells depending on the external light conditions. Senn (1908) documented light-induced chloroplast movement in a number of higher plants and algae, and the phenomenon has long been accepted as a means of optimizing photosynthetic light absorption under changing light conditions. Thus, chloroplasts c...

Currently, we are developing a computational optical biopsy technology for molecular sensing. We use the diffusion equation to model photon propagation but have a concern about the accuracy of diffusion approximation when the optical sensor is close to a bioluminescent source. We derive formulas to describe photon fluence for point and ball sources and measurement formulas for an idealized opti...

We have studied ultrafast carrier dynamics in oxidized silicon nanocrystals (NCs) and the role that surface-related states play in the various relaxation mechanisms over a broad range of photon excitation energy corresponding to energy levels below and above the direct bandgap of the formed NCs. Transient photoinduced absorption techniques have been employed to investigate the effects of surfac...

We have developed calibration and data processing techniques optimized specifically for photon-integrating pixel array detectors (PADs). Primary effects to be calibrated are pixel gain variation and pixel area variation. Gain variations originate in pixel electronics and may be corrected for via a multiplicative factor. In contrast, area variations result from doping inhomogeneities in the sens...