CCC-based muon telescope for examination of natural caves

A portable cosmic muon detector has been developed for geophysical applications: searching for large scale underground rock/soil inhomogeneities and underground cavities. The designed muon telescope called a muon tomograph is based on the recently developed closed cathode chamber (CCC) technology, which provides a cheap, easy handling, portable, and power efficient detector system able to work even in extreme conditions (e.g. high humidity, low/high temperature). The muon telescope has a detection surface of approximately 0.1 m2 with a 10 mrad angular resolution. Tests have been performed in natural caves and artificial tunnel systems as well. In this paper a summary of the first results on tomographic cavities are presented and the geophysical and possible industrial use of the cosmic muon tomographic technology is indicated

Differential control of dNTP biosynthesis and genome integrity maintenance by dUTPases

dUTPase superfamily enzymes generate dUMP, the obligate precursor for de novo dTTP biosynthesis, from either dUTP (monofunctional dUTPase, Dut) or dCTP (bifunctional dCTP deaminase/dUTPase, Dcd:dut). In addition, the elimination of dUTP by these enzymes prevents harmful uracil incorporation into DNA. These two beneficial outcomes have been thought to be related. Here we determined the relationship between dTTP biosynthesis (dTTP/dCTP balance) and the prevention of DNA uracilation in a mycobacterial model that encodes both the Dut and Dcd:dut enzymes, and has no other ways to produce dUMP. We show that, in dut mutant¬¬¬¬¬ mycobacteria, the dTTP/dCTP balance remained unchanged, but the uracil content of DNA and the mutation rate increased in parallel with the in vitro activity-loss of Dut. Conversely, dcd:dut inactivation resulted in perturbed dTTP/dCTP balance and two-fold increased mutation rate, but did not increase the uracil content of DNA. Thus, unexpectedly, the regulation of dNTP balance and the prevention of DNA uracilation are decoupled and separately brought about by the Dcd:dut and Dut enzymes, respectively. Available evidence suggests that the discovered functional separation is conserved in humans and other organisms

Underground Muography with Portable Gaseous Detectors

Muography is a novel imaging technology based on particle physics instrumentation to reveal density structure of hill-sized objects. The cosmic muon flux is attenuated while penetrating into the ground, thus the differential local flux correlates with the overburden density-length. Underground muography exploits the close-to-zenith flux, while main challenges became portability, low power consumption, and robustness against the out-of-the-laboratory environment. Various fields could benefit from this non-invasive imaging, eg. speleology, mining, archeology, or industry. Portable gaseous tracking detector systems have been designed, built, and successfully used in several underground locations. This paper presents the designed portable muography systems, the main requirements, and measurement campaigns for calibration, natural caves, and cultural heritage

The Role of a Key Amino Acid Position in Species-Specific Proteinaceous dUTPase Inhibition

Protein inhibitors of key DNA repair enzymes play an important role in deciphering physiological pathways responsible for genome integrity, and may also be exploited in biomedical research. The staphylococcal repressor StlSaPIbov1 protein was described to be an efficient inhibitor of dUTPase homologues showing a certain degree of species-specificity. In order to provide insight into the inhibition mechanism, in the present study we investigated the interaction of StlSaPIbov1 and Escherichia coli dUTPase. Although we observed a strong interaction of these proteins, unexpectedly the E. coli dUTPase was not inhibited. Seeking a structural explanation for this phenomenon, we identified a key amino acid position where specific mutations sensitized E. coli dUTPase to StlSaPIbov1 inhibition. We solved the three-dimensional (3D) crystal structure of such a mutant in complex with the substrate analogue dUPNPP and surprisingly found that the C-terminal arm of the enzyme, containing the P-loop-like motif was ordered in the structure. This segment was never localized before in any other E. coli dUTPase crystal structures. The 3D structure in agreement with solution phase experiments suggested that ordering of the flexible C-terminal segment upon substrate binding is a major factor in defining the sensitivity of E. coli dUTPase for StlSaPIbov1 inhibition

Cavity Location by Muon Tomography

Muon tomography (or muography) is one of the most effective methods for locating unknown underground voids. If the geometric conditions are favorable for the measurements, no other geophysical method can compete with it, neither when resolution nor when simplicity is considered. In the last years, thanks to the continuous R&D of our low-cost, portable muon detectors, as well as the improved data processing methods, we have completed several successful natural and artificial cavity exploration projects, demonstrating that location is possible even if the characteristic size of cavity is 5% of the rock thickness between the detector and surface. Here we present case studies carried out in Hungarian underground sites, where we could find unknown cavities and verify the method by locating known artificial shafts and adits with high precision. Reaching these unknown caves is in progress either by conventional caving exploration techniques or by drilling. Further measurements are ongoing by the new upgraded detectors. By decreasing gas consumption and supporting electric power by solar cells, we are able to measure even at remote locations without the need of any direct access, for durations of several months

Multi-Wire Detectors for Underground Muography

The use of cosmic muons in imaging large artificial or geological structures started to flourish in the last decades, with the technological advancement in particle physics instrumentations. Muography became a most effective way to locate hidden density anomalies in geological structures, which includes revealing unknown parts of natural cave systems underneath the mountains. Our group has developed a series of gaseous multi-wire particle detectors for muography applications, with targets ranging from volcanology to speleology. Advancements in durability, power consumption, portability, and acquisition system have been proven via field measurements in natural sites besides extensive laboratory testing. The poster is dedicated to give details on the main requirements, components, and solutions which are means to transform standard particle detectors to be practically applicable in underground muography. We will present the expanded scale of experimental systems, targeting upgraded high-resolution tomography, hole-fit small-scale devices, and even economical simplified versions for exploratory measurements. These muography detectors could soon become effective novel tools in geo-sciences