Fibre laser hydrophones for cosmic ray particle detection

The detection of ultra high energetic cosmic neutrinos provides a unique means to search for extragalactic sources that accelerate particles to extreme energies. It allows to study the neutrino component of the GZK cut-off in the cosmic ray energy spectrum and the search for neutrinos beyond this limit. Due to low expected flux and small interaction cross-section of neutrinos with matter large experimental set-ups are needed to conduct this type of research. Acoustic detection of cosmic rays may provide a means for the detection of ultra-high energetic neutrinos. Using relative low absorption of sound in water, large experimental set-ups in the deep sea are possible that are able to detect these most rare events, but it requires highly sensitive hydrophones as the thermo-acoustic pulse originating from a particle shower in water has a typical amplitude as low as a mPa. It has been shown in characterisation measurements that the fibre optic hydrophone technology as designed and realised at TNO provides the required sensitivity. Noise measurements and pulse reconstruction have been conducted that show that the hydrophone is suited as a particle detector.Comment: Submitted to the proceedings of "13th Topical Seminar on Innovative Particle and Radiation Detectors (IPRD13)

Mapping the Spatio-temporal Distribution of Key Vegetation Cover Properties in Lowland River Reaches, Using Digital Photography

The presence of vegetation in stream ecosystems is highly dynamic in both space and time. A digital photography technique is developed to map aquatic vegetation cover at species level, which has a very-high spatial and a flexible temporal resolution. A digital single-lens-reflex (DSLR) camera mounted on a handheld telescopic pole is used. The low-altitude (5 m) orthogonal aerial images have a low spectral resolution (Red-Green-Blue), high spatial resolution (~1.9 pixels cm-2, ~1.3 cm length) and flexible temporal resolution (monthly). The method is successfully applied in two lowland rivers to quantify four key properties of vegetated rivers: vegetation cover, patch size distribution, biomass and hydraulic resistance. The main advantages are that the method is: (i) suitable for continuous and discontinuous vegetation covers (ii) of very-high spatial and flexible temporal resolution, (iii) relatively fast compared to conventional ground survey methods, (iv) non-destructive, (v) relatively cheap and easy to use, and (vi) the software is widely available and similar open source alternatives exist. The study area should be less than 10 m wide and the prevailing light conditions and water turbidity levels should be sufficient to look into the water. Further improvements of the images processing are expected in the automatic delineation and classification of the vegetation patches

Flood routing in the river Aa using ’Femme’

The software ’Femme’, (a flexible environment for mathematically modelling the environment) is developed by the Netherlands Institute of Ecology (NIOO)(Soetaert et al., 2004) and is used for the modelling of ecological processes. Femme’s code is open source and works on a modular base. The implementation of a one dimensional hydrodynamic model into ’Femme’ to study the interaction between ecological processes and surface water flow as a driving force and the validation using field measurements is subject of this research. For example, the presence of macrophytes has an influence on the discharge by way of the entire roughness of the river, expressed by the Manning coefficient.River hydraulics is characterised by changing discharges and water levels due to rain fall, so studies have to take into account the non-permanent character of the flow. In a first phase, the river characteristics and the simplified Saint-Venant equations have been built into the model. The simplification to the parabolic and the kinematic equations allow a faster and easier solution. The parabolic model is known as the convection-diffusion equation and describes the translation, deformation and attenuation of a wave in open channels and is valid for stretches with mild slopes. The kinematic model doesn’t take into account the flattening of the wave and can only be applied in short stretches.Calculation results are presented by the variation of the discharge as a function of distance. Also the influence of the roughness coefficient is shown.The integrated study of ecological processes and surface water flow is situated in a multidisciplinary research were attention is paid to the interaction of groundwater, surface water and the ecological system in order to describe the transport of matter through river basins (Buis et al.,2005). An important study area is the river Aa near Poederlee (Belgium, Flanders, province of Antwerp), were discharge, grondwater and biomass measurements are carried out on a regular base, to perform studies in the field and to collect calibration data for the integrated hydraulics and ecology model

Multi-layer coating development for XEUS

Graded depth multi-layer coatings have the potential to optimise the performance of X-ray reflective surfaces for improved energy response. A study of deposition techniques on silicon substrates representative of the XEUS High Performance Pore Optics (HPO) technology has been carried out. Measurements at synchrotron radiation facilities have been used to confirm the excellent performance improvements achievable with Mo/Si and W/Si multilayers. Future activities that will be necessary to implement such coatings in the HPO assembly sequence are highlighted. Further coating developments that may allow an optimisation of the XEUS effective area in light of potential changes to science requirements and telescope configurations are also identified. Finally an initial measurement of effects of radiation damage within the multilayers is reported

Selective serotonin reuptake inhibitors in the treatment of generalized anxiety disorder

Selective serotonin reuptake inhibitors have proven efficacy in the treatment of panic disorder, obsessive–compulsive disorder, post-traumatic stress disorder and social anxiety disorder. Accumulating data shows that selective serotonin reuptake inhibitor treatment can also be efficacious in patients with generalized anxiety disorder. This review summarizes the findings of randomized controlled trials of selective serotonin reuptake inhibitor treatment for generalized anxiety disorder, examines the strengths and weaknesses of other therapeutic approaches and considers potential new treatments for patients with this chronic and disabling anxiety disorder

Dynamic alignment using external socket reaction moments in trans-tibial amputees

Background: Prosthetic alignment is used to optimize prosthetic functioning and comfort. Spatio-temporal and kinematic gait parameters are generally observed to guide this process. However, they have been shown to be influenced by compensations, which reduces their sensitivity to changes in alignment. Alternatively, the use of moments working at the base of the prosthetic socket, external socket reaction moments (ESRM), has been proposed to quantify prosthetic alignment. Research question: To investigate if a predetermined kinetic alignment criterion, 0Nm averaged over the stance phase, can be used to fine-tune prosthetic alignment. Methods: 10 transtibial amputees were included in this intervention study. Firstly, their prostheses were aligned using conventional alignment procedures. Kinetic parameters and Socket Comfort Score (SCS) were measured in this initial alignment (IA) condition. Subsequently, the coronal plane ESRM during gait was presented to the prosthetist in real time using a Gait Real-time Analysis Interactive Lab. The prosthetist iteratively adapted the prosthetic alignment towards a predetermined average ESRM during the stance phase of 0 Nm. At the Final Alignment (FA), kinetic parameters and SCS were measured again and a paired sample t-test was performed to compare ESRMs and SCSs between alignments. Results: A significant (p < 0.001) change was found in the absolute coronal plane ESRM (mean ± SD) from IA (|0.104| ± 0.058 Nm/kg) to FA (|0.012| ± 0.015 Nm/kg). In addition a significant (p < 0.001) change of the external coronal adduction knee moments was observed from IA (−0,127 ± 0.079 Nm/kg) to FA (−0.055 ± 0.089 Nm/kg), however this change was more variable among participants. On average, no significant (p = 0.37) change in the SCS was observed. Significance: While this study shows the potential of quantifying and guiding alignment with the assistance of kinetic criteria, it also suggests that a sole reliance on the ESRM as a single alignment criterion might be too simple

Characteristics of DNA-binding proteins determine the biological sensitivity to high-linear energy transfer radiation

Non-homologous end-joining (NHEJ) and homologous recombination repair (HRR), contribute to repair ionizing radiation (IR)-induced DNA double-strand breaks (DSBs). Mre11 binding to DNA is the first step for activating HRR and Ku binding to DNA is the first step for initiating NHEJ. High-linear energy transfer (LET) IR (such as high energy charged particles) killing more cells at the same dose as compared with low-LET IR (such as X or γ rays) is due to inefficient NHEJ. However, these phenomena have not been demonstrated at the animal level and the mechanism by which high-LET IR does not affect the efficiency of HRR remains unclear. In this study, we showed that although wild-type and HRR-deficient mice or DT40 cells are more sensitive to high-LET IR than to low-LET IR, NHEJ deficient mice or DT40 cells are equally sensitive to high- and low-LET IR. We also showed that Mre11 and Ku respond differently to shorter DNA fragments in vitro and to the DNA from high-LET irradiated cells in vivo. These findings provide strong evidence that the different DNA DSB binding properties of Mre11 and Ku determine the different efficiencies of HRR and NHEJ to repair high-LET radiation induced DSBs

DNA resection in eukaryotes: deciding how to fix the break

DNA double-strand breaks are repaired by different mechanisms, including homologous recombination and nonhomologous end-joining. DNA-end resection, the first step in recombination, is a key step that contributes to the choice of DSB repair. Resection, an evolutionarily conserved process that generates single-stranded DNA, is linked to checkpoint activation and is critical for survival. Failure to regulate and execute this process results in defective recombination and can contribute to human disease. Here, I review recent findings on the mechanisms of resection in eukaryotes, from yeast to vertebrates, provide insights into the regulatory strategies that control it, and highlight the consequences of both its impairment and its deregulation