Shock Waves in Nanomechanical Resonators

The dream of every surfer is an extremely steep wave propagating at the highest speed possible. The best waves for this would be shock waves, but are very hard to surf. In the nanoscopic world the same is true: the surfers in this case are electrons riding through nanomechanical devices on acoustic waves [1]. Naturally, this has a broad range of applications in sensor technology and for communication electronics for which the combination of an electronic and a mechanical degree of freedom is essential. But this is also of interest for fundamental aspects of nano-electromechanical systems (NEMS), when it comes to quantum limited displacement detection [2] and the control of phonon number states [3]. Here, we study the formation of shock waves in a NEMS resonator with an embedded two-dimensional electron gas using surface acoustic waves. The mechanical displacement of the nano-resonator is read out via the induced acoustoelectric current. Applying acoustical standing waves we are able to determine the anomalous acoustocurrent. This current is only found in the regime of shock wave formation. We ontain very good agreement with model calculations.Comment: 14 Pages including 4 figure

In-situ monitoring for CVD processes

Aiming towards process control of industrial high yield/high volume CVD reactors, the potential of optical sensors as a monitoring tool has been explored. The sensors selected are based on both Fourier transform infrared spectroscopy (FTIR) and tunable diode laser spectroscopy (NIR-DLS). The former has the advantage of wide spectral capability, and well established databases. NIR-DLS spectroscopy has potentially high sensitivity, laser spatial resolution, and the benefits of comparatively easier integration capabilities-including optical fibre compatibility. The proposed technical approach for process control is characterised by a 'chemistry based' feedback system with in-situ optical data as input information. The selected optical sensors continuously analyze the gas phase near the surface of the growing layer. The spectroscopic data has been correlated with process performance and layer properties which, in turn establish data basis for process control. The new process control approach is currently being verified on different industrialised CVD coaters. One of the selected applications deals with the deposition of SnO2 layers on glass based on the oxidation of (CH3)2SnCl2, which is used in high volume production for low-E glazing

AN-Type Fittings in the International Space System (ISS) Node 2 Ammonia System Technical Assessment Report

Based on an anonymous request, an NESC Assessment Team was formed to investigate potential leakage problems from the ISS Program's Node 2 Anhydrous Ammonia System AN fittings. The Team's charter was to provide the ISS Program with a path to follow, which could include testing, to ensure the ISS Program felt confident that the AN fittings' leakage would not exceed specified limits in orbit. The findings from that assessment are contained in this document

Sensitivity and reproducibility of standardized-competitive RT-PCR for transcript quantification and its comparison with real time RT-PCR

BACKGROUND: Probe based detection assays form the mainstay of transcript quantification. Problems with these assays include varying hybridization efficiencies of the probes used for transcript quantification and the expense involved. We examined the ability of a standardized competitive RT-PCR (StaRT PCR) assay to quantify transcripts of 4 cell cycle associated genes (RB, E2F1, CDKN2A and PCNA) in two cell lines (T24 & LD419) and compared its efficacy with the established Taqman real time quantitative RT-PCR assay. We also assessed the sensitivity, reproducibility and consistency of StaRT PCR. StaRT PCR assay is based on the incorporation of competitive templates (CT) in precisely standardized quantities along with the native template (NT) in a PCR reaction. This enables transcript quantification by comparing the NT and CT band intensities at the end of the PCR amplification. The CT serves as an ideal internal control. The transcript numbers are expressed as copies per million transcripts of a control gene such as β-actin (ACTB). RESULTS: The NT and CT were amplified at remarkably similar rates throughout the StaRT PCR amplification cycles, and the coefficient of variation was least (<3.8%) when the NT/CT ratio was kept as close to 1:1 as possible. The variability between the rates of amplification in different tubes subjected to the same StaRT PCR reaction was very low and within the range of experimental noise. Further, StaRT PCR was sensitive enough to detect variations as low as 10% in endogenous actin transcript quantity (p < 0.01 by the paired student's t-test). StaRT PCR correlated well with Taqman real time RT-PCR assay in terms of transcript quantification efficacy (p < 0.01 for all 4 genes by the Spearman Rank correlation method) and the ability to discriminate between cell types and confluence patterns. CONCLUSION: StaRT PCR is thus a reliable and sensitive technique that can be applied to medium-high throughput quantitative transcript measurement. Further, it correlates well with Taqman real time PCR in terms of quantitative and discriminatory ability. This label-free, inexpensive technique may provide the ability to generate prognostically important molecular signatures unique to individual tumors and may enable identification of novel therapeutic targets

High fluoride and low calcium levels in drinking water is associated with low bone mass, reduced bone quality and fragility fractures in sheep

SUMMARY: Chronic environmental fluoride exposure under calcium stress causes fragility fractures due to osteoporosis and bone quality deterioration, at least in sheep. Proof of skeletal fluorosis, presenting without increased bone density, calls for a review of fracture incidence in areas with fluoridated groundwater, including an analysis of patients with low bone mass. INTRODUCTION: Understanding the skeletal effects of environmental fluoride exposure especially under calcium stress remains an unmet need of critical importance. Therefore, we studied the skeletal phenotype of sheep chronically exposed to highly fluoridated water in the Kalahari Desert, where livestock is known to present with fragility fractures. METHODS: Dorper ewes from two flocks in Namibia were studied. Chemical analyses of water, blood and urine were executed for both cohorts. Skeletal phenotyping comprised micro-computer tomography (μCT), histological, histomorphometric, biomechanical, quantitative backscattered electron imaging (qBEI) and energy-dispersive X-ray (EDX) analysis. Analysis was performed in direct comparison with undecalcified human iliac crest bone biopsies of patients with fluoride-induced osteopathy. RESULTS: The fluoride content of water, blood and urine was significantly elevated in the Kalahari group compared to the control. Surprisingly, a significant decrease in both cortical and trabecular bones was found in sheep chronically exposed to fluoride. Furthermore, osteoid parameters and the degree and heterogeneity of mineralization were increased. The latter findings are reminiscent of those found in osteoporotic patients with treatment-induced fluorosis. Mechanical testing revealed a significant decrease in the bending strength, concurrent with the clinical observation of fragility fractures in sheep within an area of environmental fluoride exposure. CONCLUSIONS: Our data suggest that fluoride exposure with concomitant calcium deficit (i) may aggravate bone loss via reductions in mineralized trabecular and cortical bone mass and (ii) can cause fragility fractures and (iii) that the prevalence of skeletal fluorosis especially due to groundwater exposure should be reviewed in many areas of the world as low bone mass alone does not exclude fluorosis

The Vehicle, November 1960, Vol. 3 no. 1

CONTENTS To the ReaderStaffpage 2 N’ = N : 1Donald C. Blairpage 3 ConsistencyDonald C. Blairpage 3 Unto MeLinda Kay Campbellpage 4 The Meek Shall InheritE. J. B. page 5 The Infinite QuestLarry W. Dudleypage 6 Dreamer’s DawnMike Hindmanpage 7 BirthNancy Coepage 7 The Lost DutchmanDonald C. Blairpage 8 W. E. Noonan IRobert S. Hodgepage 8 A Soldier’s OrdealDonald E. Shephardsonpage 9 Personal PossessionMary Beilpage 11 Thine The GloryDonald C. Blairpage 12 The ThornJan Holstlawpage 13 A Lord’s Day MorningLinda Campbellpage 14 Observations of a 6-Year-OldTom McPeakpage 15 Jewels of TimeJudith Jerintspage 16 LavenderE. J. B. page 16https://thekeep.eiu.edu/vehicle/1008/thumbnail.jp

Taxonomy Working Group Final Report

The purpose of the Taxonomy Working Group was to develop a proposal for a common taxonomy to be used by all NASA projects in the classifying of nonconformances, anomalies, and problems. Specifically, the group developed a recommended list of data elements along with general suggestions for the development of a problem reporting system to better serve NASA's need for managing, reporting, and trending project aberrant events. The Group's recommendations are reported in this document

Who gets the ventilator? A multicentre survey of intensivists' opinions of triage during the first wave of the COVID-19 pandemic

Background The COVID-19 pandemic has caused a shortage of intensive care resources. Intensivists' opinion of triage and ventilator allocation during the COVID-19 pandemic is not well described. Methods This was a survey concerning patient numbers, bed capacity, triage guidelines, and three virtual cases involving ventilator allocations. Physicians from 400 ICUs in a research network were invited to participate. Preferences were assessed with a five-point Likert scale. Additionally, age, gender, work experience, geography, and religion were recorded. Results Of 437 responders 31% were female. The mean age was 44.4 (SD 11.1) with a mean ICU experience of 13.7 (SD 10.5) years. Respondents were mostly European (88%). Sixty-six percent had triage guidelines available. Younger patients and caretakers of children were favoured for ventilator allocation although this was less clear if this involved withdrawal of the ventilator from another patient. Decisions did not differ with ICU experience, gender, religion, or guideline availability. Consultation of colleagues or an ethical committee decreased with age and male gender. Conclusion Intensivists appeared to prioritise younger patients for ventilator allocation. The tendency to consult colleagues about triage decreased with age and male gender. Many found such tasks to be not purely medical and that authorities should assume responsibility for triage during resource scarcity.publishedVersio