Dose-Dependence of Radiotherapy-Induced Changes in Serum Levels of Choline-Containing Phospholipids; The Importance of Lower Doses Delivered to Large Volumes of Normal Tissues

Conformal radiotherapy is a primary treatment in head and neck cancer, which putative adverse effects depend on relatively low doses of radiation delivered to increased volumes of normal tissues. Systemic effects of such treatment include radiation-induced changes in serum lipid profile, yet dose- and volume-dependence of these changes remain to be established. Here we analyzed levels of choline-containing phospholipids in serum samples collected consecutively during the radiotherapy used as the only treatment modality. The LC-MS approach applied in the study enabled the detection and quantitation of 151 phospholipids, including (lyso)phosphatidylcholines and sphingomyelins. No statistically significant differences were found in the pre-treatment samples from patients with different location and stage of cancer. To compensate for potential differences between schemes of radiotherapy the biologically effective doses were calculated and used in the search of correlations with specific lipid levels. We found that the levels of several phospholipids depended on the maximum dose delivered to the gross tumor volume and total radiation energy absorbed by the patient’s body. Increased doses correlated with increased levels of sphingomyelins and reduced levels of phosphatidylcholines. Noteworthy, serum phospholipid levels were associated mainly with volumes of normal tissues irradiated with relatively low doses (i.e., total accumulated dose 20 Gy), which indicated the importance of such effects on the systemic response of the patient’s organism to IMRT.

The Determination of Effective Beamwidth of Ku Band Profiling Radar Based on Waveform Matching Method in the Boreal Forest of Finland

Radar scientists typically define the radar beamwidth as a half-power beamwidth (HPBW) in the main lobe of the antenna pattern. However, the microwave radiations outside radar HPBW might also backscatter into the radar receiver and change the distribution of the received signal. To determine an actual and effective beamwidth illuminated on the measured targets, we first generate the simulated-waveforms derived from coincident lidar points and radar equation and then develop a waveform matching method to seek out an optimal beamwidth based on the 95% threshold of correlation coefficients between radar waveforms and the simulated-waveforms. The 8565 measurements of a Ku-band profiling radar named Tomoradar and coincident lidar data in a widespread heterogeneous forest area of southern Finland are employed for resolving the effective beamwidth. The results reveal that about 97% of the effective beamwidth are larger than Tomoradar HPBW, but the effective beamwidth could be changeable for each measurement due to variations in the scattering properties of vegetation. Thus, a fixed average effective beamwidth (AEBW) with 0.1-degree resolution is introduced to determine Tomoradar cone according to the effective beamwidth and corresponding proportions. We discover that Tomoradar AEBW is approximately approaching to 8°, which is larger than Tomoradar HPBW of 6°. If we regard AEBW as the actual Tomoradar beamwidth rather than HPBW, the simulated-waveforms have substantially stronger correlation strength with Tomoradar waveforms, and canopy tops derived from lidar data within Tomoradar AEBW are much closer to those extracted from Tomoradar waveforms. The results demonstrate that radar AEBW is a more appropriate reference for designing radar antenna and selecting the region size of validation data such as lidar points or the ground truth. However, considering that radar AEBW is variable for different radar antenna pattern, we suggest that actual radar beamwidth should be defined with a fraction of total radiation energy within radar AEBW, just like the definition of laser divergence of lidar based on the percentage of transmitted laser energy. In this paper, for a forest inventory research case, the fraction of total radiation energy within the AEBW for radar system is supposed to be 91%.

QUANTUM LARMOR RADIATION FROM A MOVING CHARGE IN AN ELECTROMAGNETIC PLANE WAVE BACKGROUND

We extend our previous work [Phys. Rev. D83, 045030 (2011)], which investigated the first-order quantum effect in the Larmor radiation from a moving charge in a spatially homogeneous time-dependent electric field. Specifically, we investigate the quantum Larmor radiation from a moving charge in a monochromatic electromagnetic plane wave background based on the scalar quantum electrodynamics at the lowest order of the perturbation theory. Using the in–in formalism, we derive the theoretical formula of the total radiation energy from a charged particle in the initial states being at rest and being in a relativistic motion. Expanding the theoretical formula in terms of the Planck constant ℏ, we obtain the first-order quantum effect on the Larmor radiation. The quantum effect generally suppresses the total radiation energy compared with the prediction of the classical Larmor formula, which is a contrast to the previous work. The reason is explained by the fact that the radiation from a moving charge in a monochromatic electromagnetic plane wave is expressed in terms of the inelastic collisions between an electron and photons of the background electromagnetic waves.

Bremsstrahlung and Pair Creation by a Photon in the Spacetime of a Cosmic String

We consider two tree-graph processes in the spacetime of an infinite, straight and static cosmic string, namely Bremsstrahlung and electron–positron pair production. Results based on a simplified model with scalar fields which were obtained by other authors are extended to the more realistic QED case. In empty Minkowski spacetime, energy and momentum conservation preclude these processes. In spite of the local flatness of the metric, it is a topological defect that gives rise to non-conservation of momentum in the plane perpendicular to the string. Analytic expressions for the total transition probabilities and, in the case of Bremsstrahlung, the total radiation energy are found and compared with the results for the scalar field model. In a sense, the cylindrical mode solutions of the Dirac equation allow a spatial localisation of the decay processes relative to the string axis.

Some Evidence of Radiolysis in a Uranium ore Body - Quantification and Interpretation

Locally oxidising conditions in the near-field of the Cigar Lake uranium deposit was observed. Ongoing processes of water radiolysis has also been predicted previously by our mass transport model. In the ore there was an enhanced concentration of helium, hydrogen and sulphate. Sulphate is the only oxidising species of substantial amount in the groundwater samples, and is possibly indirectly produced by water radiolysis and oxidation of sulphides. The ongoing oxidant production rate has been calculated by the mass transport model.In this paper, the issue of water radiolysis is addressed from a more fundamental angle of approach. The maximum oxidant production rate is calculated based on the assumptions of geometric dispersion of the ore constituents, the estimate of the total radiation energy, the fraction of energy deposited into the pore water, and the G-values of water. The results show that only a few percent of the total radiation energy is deposited into the pore water to cause water radiolysis. If the recombination factor projected by other researchers are accounted for, the oxidant production rate thus calculated agrees with the present-day ongoing oxidant production rate predicted by the mass transport model.

Experiments with a wire array Z pinch on the inductive storage generator

We report experiments that were carried out at the inductive storage machine GIT-4 with wire arrays. The tungsten wire array parameters were the following: the mass per centimeter was equal to 370 μg/cm, the length was 4 cm, and the initial radius was 0.2 cm. When the wire array current was 1.5 MA, the rise time was 100 ns and the total radiation energy was 50 kJ at the 80–100–kJ energy transferred to the wire array.