PURPOSE In an attempt to reduce treatment time in corneal collagen cross-linking (CXL) with riboflavin and ultraviolet-A (UV-A), recent protocol modifications include shorter irradiation times at higher fluence, while maintaining constant total applied energy (Bunsen-Roscoe law of reciprocity). While such parameter changes might produce similar biological results within a certain range, the lim...

The question of the appropriate extrapolation to low dose has long been a subject of controversy. A linear no-threshold model is favored by regulatory bodies as the basis of RBE assignments and estimates of radiation hazards to the general population. This model is largely supported by extensive application of the linear-quadratic survival formula "fitted" statistically to a wide variety of exp...

The presented virtual energy fluence (VEF) model of the patient-independent part of the medical linear accelerator heads, consists of two Gaussian-shaped photon sources and one uniform electron source. The planar photon sources are located close to the bremsstrahlung target (primary source) and to the flattening filter (secondary source), respectively. The electron contamination source is locat...

Several groups worldwide have proposed various concepts for improving megavoltage (MV) radiotherapy that involve irradiating patients in the presence of a magnetic field-either for image guidance in the case of hybrid radiotherapy-MRI machines or for purposes of introducing tighter control over dose distributions. The presence of a magnetic field alters the trajectory of charged particles betwe...

We have examined phytochrome regulated changes in transcript abundance for 11 different light regulated mRNAs in developing pea buds. Fluence-response curves were measured for changes in transcript abundance in response to red light pulses in both the low and very low fluence ranges. Most transcripts show only low fluence responses, with a threshold of approximately 10 micromoles per square met...

Introduction. In the International Code of Practice for dosimetry TRS-398 published by International Atomic Energy Agency (IAEA), water is recommended as the reference medium for the determination of absorbed dose for high-energy electron beams. Plastic phantoms may be used under certain circumstances for electron beam dosimetry for beam qualities R50 < 4g/cm2 (E0 below 10 MeV). In our study, w...

We propose a physical model of gamma-ray burst spectral evolution in which impulsively accelerated nonthermal leptons cool by saturated Compton upscattering of soft photons. This model naturally explains the recently discovered exponential decay of the spectral break energy with photon fluence, the hard-to-soft spectral evolution patterns, and other spectral and temporal properties of gamma-ray...

BACKGROUND AND OBJECTIVES Molecular oxygen in the tissue to be treated by photodynamic therapy (PDT) is critical for photodynamic cell killing. The fluence rate of PDT light delivery has been identified as an important modulator of tissue oxygenation and treatment outcome. This article provides supporting evidence for the role of fluence rate in PDT and discusses the underlying mechanisms. ST...

One of the most important discoveries in the observation of gamma-ray bursts (GRBs) is that the total energy emitted by a GRB in γ-rays has a very narrow distribution around 1051 erg, which has led people to claim that GRBs are standard energy explosions. As people made the claim they have ignored the selection biases which must be important since GRB observations are strongly fluence or flux-l...

Milagro is a wide field (2 sr) high duty cycle (>90%) ground-based water Cherenkov detector built to observe extensive air showers produced by high energy particles interacting in the Earth’s atmosphere. Milagro records extensive air showers in the energy range 100 GeV to 100 TeV, as well as the counting rates of the individual photomultiplier tubes in the detector. The individual tube counting...