Radiation-induced lowered neurogenesis associated with shortened latency of inhibitory avoidance memory response

The neural system is less sensitive to radiation than other late-responding organs and tissues such as the kidney and lung. The generation of new neurons in the adult mammalian brain has been documented in several works. Many studies show that adult hippocampal neurogenesis relates to hippocampal function, in several ways. In this study, we assessed the effect of single and fractionated cobalt radiation on neurogenesis in the dentate gyrus of the hippocampal formation. The irradiation time for delivering 2 Gy (for fractionated dose radiation) and 10 Gy (for single dose radiation) at maximum depth were respectively 1.98 min and 9.92 min. To study the association with memory function we examined inhibitory avoidance memory using a step-through device. Brains were withdrawn and fixed, and then sections were stained with cresyl violet for neurons. We found that a 10 Gy dose can induce lower neurogenesis in the dentate gyrus of the hippocampus (p < 0.05), in such a way that a fractionated dose (5 fractions of 2 Gy) is more effective than a single dose (one fraction of 10 Gy). Moreover, a fractionated dose could reduce step-through latency corresponding to damaged inhibitory avoidance memory (p < 0.05). Synergic action of an anaesthetic drug may be the cause of more reduction of neurogenesis in fractionated irradiated rats. There was no significant difference in latency of the inhibitory avoidance memory response between the single 10 Gy group and the sham group, while fractionated 10 Gy could reduce latency. Different mechanisms of action in the two regimens of irradiation may be a reason

Radiation Therapy Medical Physics Review – Delivery, Interactions, Safety, Feasibility, and Head to Head Comparisons of the Leading Radiation Therapy Techniques

Radiation therapy uses high energy radiation to kill cancer cells. Radiation therapy for cancer treatment can take the form of photon therapy (using x-rays and gamma rays), or charged particle therapy including proton therapy and electron therapy. Within these categories, numerous methods of delivery have been developed. For example, a certain type of radiation can be administered by a machine outside of the body, called external-beam radiation therapy, or by a “seed” placed inside of the body near cancer cells, called internal radiation therapy or brachytherapy. Approximately half of all cancer patients receive radiation therapy, and the form of radiation treatment depends on the type of tumor, location of the tumor, available resources, and characteristics of the individual receiving treatment. In the current paper, we discuss and review the various forms of radiation therapy, the physics behind these treatments, the effectiveness of each treatment type compared with the others, the latest research on radiation therapy treatment, and future research directions. We found that proton therapy is the most promising and effective form of radiation therapy, with photon methods such as intensity modulated radiation therapy, 3D-conformal radiation therapy, image guided radiation therapy, and volumetric modulated radiation therapy also showing very good comparative performance

Lightning radiation field due to channel tortuosity and branching

The effect of lightning channel branching on the temporal waveform of the radiated fields of the return stroke is modeled. The effect of branching is isolated, and compared to the effect of tortuosity of an unbranched channe

The Blackbody Radiation Spectrum Follows from Zero-Point Radiation and the Structure of Relativistic Spacetime in Classical Physics

The analysis of this article is entirely within classical physics. Any attempt to describe nature within classical physics requires the presence of Lorentz-invariant classical electromagnetic zero-point radiation so as to account for the Casimir forces between parallel conducting plates at low temperatures. Furthermore, conformal symmetry carries solutions of Maxwell's equations into solutions. In an inertial frame, conformal symmetry leaves zero-point radiation invariant and does not connect it to non-zero-temperature; time-dilating conformal transformations carry the Lorentz-invariant zero-point radiation spectrum into zero-point radiation and carry the thermal radiation spectrum at non-zero temperature into thermal radiation at a different non-zero-temperature. However, in a non-inertial frame, a time-dilating conformal transformation carries classical zero-point radiation into thermal radiation at a finite non-zero-temperature. By taking the no-acceleration limit, one can obtain the Planck radiation spectrum for blackbody radiation in an inertial frame from the thermal radiation spectrum in an accelerating frame. Here this connection between zero-point radiation and thermal radiation is illustrated for a scalar radiation field in a Rindler frame undergoing relativistic uniform proper acceleration through flat spacetime in two spacetime dimensions. The analysis indicates that the Planck radiation spectrum for thermal radiation follows from zero-point radiation and the structure of relativistic spacetime in classical physics.Comment: 21 page

Chiral Cherenkov and chiral transition radiation in anisotropic matter

A significant contribution to the electromagnetic radiation by a fast electric charge moving in anisotropic chiral matter arises from spontaneous photon radiation due to the chiral anomaly. While such a process, also known as the "vacuum Cherenkov radiation", is forbidden in the QED vacuum, it can occur in chiral matter, where it is more appropriate to call it the "chiral Cherenkov radiation". Its contribution to the radiation spectrum is of order $\alpha^2$ compared to $\alpha^3$ of the bremsstrahlung. I derive the frequency spectrum and the angular distribution of this radiation in the high energy limit. The quantum effects due to the hard photon emission and the fermion mass are taken into account. The obtained spectra are analyzed in the case the quark-gluon plasma and a Weyl semimetal.Comment: 13 pages, 6 figure

Radiation Risks and Mitigation in Electronic Systems

Electrical and electronic systems can be disturbed by radiation-induced effects. In some cases, radiation-induced effects are of a low probability and can be ignored; however, radiation effects must be considered when designing systems that have a high mean time to failure requirement, an impact on protection, and/or higher exposure to radiation. High-energy physics power systems suffer from a combination of these effects: a high mean time to failure is required, failure can impact on protection, and the proximity of systems to accelerators increases the likelihood of radiation-induced events. This paper presents the principal radiation-induced effects, and radiation environments typical to high-energy physics. It outlines a procedure for designing and validating radiation-tolerant systems using commercial off-the-shelf components. The paper ends with a worked example of radiation-tolerant power converter controls that are being developed for the Large Hadron Collider and High Luminosity-Large Hadron Collider at CERN.Comment: 19 pages, contribution to the 2014 CAS - CERN Accelerator School: Power Converters, Baden, Switzerland, 7-14 May 201