Modelling of simple cases in view of active stabilisation for a future linear collider

Final focus magnet stabilisation is an important issue when working with nanometre size beams. The present study focuses on mechanical stabilisation. As a first step, the case of a 1m free-fixed aluminium beam placed on a table with active stabilisation has been studied. This work describes three aspects, namely, sensors and actuators to measure and compensate ground motion, mechanical simulations and a feedback loop. Measurements done with low frequency velocity sensors (down to 0.1Hz) in our Annecy lab during office hours show that the displacement RMS on the active table is 1nm at 4Hz compared to 10nm without active stabilisation. Simulations of the dynamic response of the beam have been compared to measurements done with accelerometers placed on the clamping and on the free end of the aluminium beam. The results are in good agreement. We are therefore able to predict by simulation the response of a structure subjected to an external excitation. A first sketch of a feedback loop to compensate specific vibrations has also been developed and allows the simultaneous elimination of several resonance peaks on a reduced-size mock-up. This algorithm will be applied to stabilise a larger mock-up, leading to more realistic experimental conditions. In future tests, the active table will globally stabilise in a range of frequencies from 0.5Hz to 50Hz whereas the feedback loop will compensate single strong resonances

Crystalline phases involved in the hydration of calcium silicate-based cements: Semi-quantitative Rietveld X-ray diffraction analysis

Chemical comparisons of powder and hydrated forms of calcium silicate cements (CSCs) and calculation of alterations in tricalcium silicate (Ca3SiO5) calcium hydroxide (Ca(OH)2) are essential for understanding their hydration processes. This study aimed to evaluate and compare these changes in ProRoot MTA, Biodentine and CEM cement. Powder and hydrated forms of tooth coloured ProRoot MTA, Biodentine and CEM cement were subjected to X-ray diffraction (XRD) analysis with Rietveld refinement to semi-quantitatively identify and quantify the main phases involved in their hydration process. Data were reported descriptively. Reduction in Ca3SiO5 and formation of Ca(OH)2 were seen after the hydration of ProRoot MTA and Biodentine; however, in the case of CEM cement, no reduction of Ca3SiO5 and no formation of Ca(OH)2 were detected. The highest percentages of amorphous phases were seen in Biodentine samples. Ettringite was detected in the hydrated forms of ProRoot MTA and CEM cement but not in Biodentine

The loop structure and the RNA helicase p72/DDX17 influence the processing efficiency of the mice miR-132

miRNAs are small RNAs that are key regulators of gene expression in eukaryotic organisms. The processing of miRNAs is regulated by structural characteristics of the RNA and is also tightly controlled by auxiliary protein factors. Among them, RNA binding proteins play crucial roles to facilitate or inhibit miRNA maturation and can be controlled in a cell, tissue and species-specific manners or in response to environmental stimuli. In this study we dissect the molecular mechanism that promotes the overexpression of miR-132 in mice over its related, co-transcribed and co-regulated miRNA, miR-212. We have shown that the loop structure of miR-132 is a key determinant for its efficient processing in cells. We have also identified a range of RNA binding proteins that recognize the loop of miR-132 and influence both miR-132 and miR-212 processing. The DEAD box helicase p72/DDX17 was identified as a factor that facilitates the specific processing of miR-132

Tumor surveillance by circulating microRNAs: a hypothesis

A growing body of experimental evidence supports the diagnostic relevance of circulating microRNAs in various diseases including cancer. The biological relevance of circulating microRNAs is, however, largely unknown, particularly in healthy individuals. Here, we propose a hypothesis based on the relative abundance of microRNAs with predominant tumor suppressor activity in the blood of healthy individuals. According to our hypothesis, certain sets of circulating microRNAs might function as a tumor surveillance mechanism exerting continuous inhibition on tumor formation. The microRNA-mediated tumor surveillance might complement cancer immune surveillance

Validating a traffic conflict prediction technique for motorways using a simulation approach

With the ever-increasing advancements in the technology of driver assistant systems, there is a need for a comprehensive way to identify traffic conflicts to avoid collisions. Although significant research efforts have been devoted to traffic conflict techniques applied for junctions, there is dearth of research on these methods for motorways. This paper presents the validation of a traffic conflict prediction algorithm applied to a motorway scenario in a simulated environment. An automatic video analysis system was developed to identify lane change and rear-end conflicts as ground truth. Using these conflicts, the prediction ability of the traffic conflict technique was validated in an integrated simulation framework. This framework consisted of a sub-microscopic simulator, which provided an appropriate testbed to accurately simulate the components of an intelligent vehicle, and a microscopic traffic simulator able to generate the surrounding traffic. Results from this framework show that for a 10% false alarm rate, approximately 80% and 73% of rear-end and lane change conflicts were accurately predicted, respectively. Despite the fact that the algorithm was not trained using the virtual data, the sensitivity was high. This highlights the transferability of the algorithm to similar road networks, providing a benchmark for the identification of traffic conflict and a relevant step for developing safety management strategies for autonomous vehicles

On the Use of Auxetics in Footwear: Investigating the Effect of Padding and Padding Material on Forefoot Pressure in High Heels

Although high heels are known to affect the biomechanics of human movement, most notably by increasing forefoot plantar pressure, it is commonly worn due to the influence of fashion. To deal with the resulting clinical issues, some prescriptions include the use of cushioning pads to redistribute the plantar loads and increase comfort. This preliminary study has sought to investigate whether auxetic foam would be a good candidate for the redistribution of plantar loafing in the forefoot when compared to a more traditional material. From the results obtained, it was shown that auxetic foam demonstrated a decrease in forefoot peak plantar pressure while a commercial product, a material traditionally used for plantar cover paddings, increased pressure in the region of the second–fourth Metatarsophalangeal Joint. This demonstrates the potential for auxetic materials to become the material of choice for such applications, especially since it can be further remodeled until its properties can produce a significant forefoot pressure reduction

Replication intermediates that escape Dna2 activity are processed by Holliday junction resolvase Yen1

Cells have evolved mechanisms to protect, restart and repair perturbed replication forks, allowing full genome duplication, even under replication stress. Interrogating the interplay between nuclease-helicase Dna2 and Holliday junction (HJ) resolvase Yen1, we find the Dna2 helicase activity acts parallel to homologous recombination (HR) in promoting DNA replication and chromosome detachment at mitosis after replication fork stalling. Yen1, but not the HJ resolvases Slx1-Slx4 and Mus81-Mms4, safeguards chromosome segregation by removing replication intermediates that escape Dna2. Post-replicative DNA damage checkpoint activation in Dna2 helicase-defective cells causes terminal G2/M arrest by precluding Yen1-dependent repair, whose activation requires progression into anaphase. These findings explain the exquisite replication stress sensitivity of Dna2 helicase-defective cells, and identify a non-canonical role for Yen1 in the processing of replication intermediates that is distinct from HJ resolution. The involvement of Dna2 helicase activity in completing replication may have implications for DNA2-associated pathologies, including cancer and Seckel syndrome