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The ICCHIBAN intercomparison experiments for space radiation instruments using ion beams from accelerators have been performed at HIMAC, Chiba, Japan and Loma Linda Univ. Medical Center (LLUMC), California, USA. Investigators from 17 laboratories in 10 nations participated in these experiments. To date, five intercomparison experiments have performed at HIMAC using heavy ion beams, including He, C, Ne, Si, Ar and Fe, that are of importance in the galactic cosmic-ray spectrum. At LLUMC, an experiment was performed using a proton beam to simulate a solar particle event. Additional experiments, including an intercomparison using relativistic Fe, Si and proton beams at NSRL, are currently being planned. The objectives of the ICCHIBAN intercomparison experiments are to 1) determine the response of space radiation instruments to heavy ions and protons; 2) intercompare the response and sensitivity of these instruments; 3) establish and characterize an accelerator-based "reference standard" against which these instruments can be calibrated.The participants of ICCHIBAN-1 and ICCHIBAN-2 experiments have analyzed their results and submitted reports to the ICCHIBAN working group (ICWG). ICWG has summarized the results and published as HIMAC Technical Report. For active instruments, the LET distributions from instruments using Si detectors and from TEPC were good agreement for 12C exposures, although the width of the main peak was broader for the TEPC exposures due to differences in the operating principles of the instruments. Several active instruments were found to lack sensitivity to high LET particles including the Fe beam used in the intercomparison. For passive dosimeters, ICWG exposed participants\u27 dosimeters to both \u27known\u27 and \u27blind\u27 conditions. The participants analyzed their dosimeters from the \u27known\u27 exposures to measure dose linearity and obtain high-LET dose efficiency response. In the blind exposure simulating an actual exposure in space (97% low LET particles and 3% high LET particles) most of dosimeters showed good agreement with the reference ion chamber measurements. But, in other blind exposures where high LET radiation was dominant, there was larger disagreement. This was largely due to the lack of efficiency of TLD and OSL dosimeters in registering dose from high-LET particles. Some of participants applied correction methods to the TLD or OSL data that greatly improved their response to high-LET particles. Only those passive detector laboratories that used a combination of CR-39 PNTD and TLD were able to measure both dose and dose equivalent.3rd International Workshop on Space Radiation Researc

Structural studies of toxins and toxin-like proteins

Toxins are an ancient mechanism of interaction between cohabiting organisms: basal concentrations serve as an informal cue, enough as a warning signal; too much and the dialog is over. As such, the evolutionary race to arms led to the development of a vast trove of molecular unique biochemical mechanisms, from small molecules to protein toxins. The study of these mechanisms is not only essential for the treatment of toxin-related pathologies, but also as the potential source for novel therapeutic drugs. In this thesis, a series of studies of different toxins and toxin-like proteins are compiled. To further understand the biological function and relevance of each toxin, their detailed study and characterization were pursued. Here are described the advances made using a combination of different complementary biophysical and structural methods, chosen in each case to specifically target each molecule characteristics. In the first chapter, the general biological theme of this thesis is introduced: toxins, particularly protein toxins, their description, and classification, as well as the role of structural biology in the study of proteins in general. To set the theoretical background of the following chapters, are also described the general principles of two of the most prominent methods for the study of proteins in structural biology: nuclear magnetic resonance (NMR) spectroscopy, and X-ray diffraction. In the second chapter, the interaction between human FKBP12 chaperone protein and two similar bacterial small molecule toxins is detailed: rapamycin initially used as an anti-fungal before the discovery of its potent immunosuppressive properties as a mTOR inhibitor; and mycolactone, a bacterial toxin responsible for the disease Buruli ulcers in humans. In the third chapter, the cell-free protein expression system is introduced as a technique best suited for the expression of cytotoxic proteins and otherwise difficult targets, as explored further in the following chapters. In the fourth chapter, advancements towards the structural and conformational characterization of the membrane-inserted state of two similar pore-forming toxins are detailed: the bacterial Colicin Ia protein; and the human Bax protein, an apoptosis effector; using X-ray crystallography, solution NMR and solid-state NMR. Finally, in the fifth chapter, two FIC-domain bacterial toxins are investigated: the bacterial VbhTA toxin-antitoxin protein complex, and the structural determination with its cognate target, DNA GyraseB enzyme; and the auto-activation of the bacterial NmFIC protein; in both cases using a combination of X-ray crystallography and NMR spectroscopy, as well as other biophysical techniques

Study on the reusability of fluorescent nuclear track detectors using optical bleaching

Fluorescent nuclear track detectors (FNTDs) based on Al${_2}$O${_3}$:C,Mg crystals are luminescent detectors that can be used for dosimetry and detection of charged particles and neutrons. These detectors can be utilised for imaging applications where a reasonably high track density, approximately of the order of 1 $\times$ $10^4$ tracks in an area of 100 $\times$ 100 $\mu$m$^2$, is required. To investigate the reusability of FNTDs for imaging applications, we present an approach to perform optical bleaching under the required track density conditions. The reusability was assessed through seven irradiation-bleaching cycles. For the irradiation, the studied FNTD was exposed to alpha-particles from an $^{241}$Am radioactive source. The optical bleaching was performed by means of ultraviolet laser light with a wavelength of 355 nm. Three dedicated regions on a single FNTD with different accumulated track densities and bleaching conditions were investigated. After every irradiation-bleaching cycle, signal-to-noise ratio was calculated to evaluate FNTD performance. It is concluded that FNTDs can be reused at least seven times for applications where accumulation of a high track density is required

LET measurements in water using CR-39 plastic nuclear track detector for therapeutic carbon ion beams

Workshop on physical, biological and medical aspects of high-LET radiation energy transfer in the matte

Space radiation dosimetry and the fluorescent nuclear track detector

The 3rd International Workshop on Nuclear Emulsion Techniques　− Modern techniques of nuclear emulsion and their applications

Intercomparison of passive radiation monitors in Russian segment of ISS (Space Intercomparison/BRADOS II)

Workshop on physical, biological and medical aspects of high-LET radiation energy transfer in the matte

Space radiation dosimetry and the fluorescent nuclear track detector

3rd International Workshop on Nuclear emulsion Technique