Micromachined capacitive long-range displacement sensor

First measurement results are presented for a surface-micromachined long-range (50– 100 μm) periodic capacitive position sensor. The sensor consists of two periodic geometries (period = 10 μm) sliding along each other with minimum spacing of about 1.5 μm. The relative displacement between the two, results in a periodic change in capacitance. An electrostatic comb-drive actuator is employed to generate displacements. Measured maximum capacitance change ΔC=0.72 fF corresponds to simulation results but needs better shielding from external noise sources. The results show this sensorconcept can potentially lead towards long-range nano-positioning control of microactuator systems

Micromachined capacitive displacement sensor for long-range nano-positioning

Integrated long-range position sensing with high accuracy will be of paramount importance for high-potential applications in a.o. future probe-based datastorage and microscopy applications [1], provided that nm position accuracy can be obtained over a range of tens of micrometers or more. This work presents the design, fabrication and measurements for an integrated incremental capacitive long-range position sensor for nano-positioning of microactuators. For compactness, economical viability and optimal performance, the aim has been to fully integrate sensor and actuator through micromachining technology, without additional micro-assembly. Two related concepts are presented and evaluated through analysis, 2D-Finite-Element Simulations and experimental assessment. The sensors consist of two periodic geometries (period ≈ 8-16μm) on resp. a slider, movable in x-direction, and sense-structures, movable in y-direction, at both sides of the slider, Fig. 1. In ICMM the displacement of the slider is measured by measuring the periodic change in capacitance ΔCs(x) with a charge-amplifier and synchronous detection technique [2]. Using sense-actuators, the gap-distance between sense-structures and slider is made smaller than is possible with standard available photo-lithography (< 2 μm), thus increasing the capacitance and the S-N Ratio

Mechanobiology of orthodontic tooth movement: An update.

The purpose of this review is to provide an update on the changes at the cellular and tissue level occurring during orthodontic force application. For the understanding of this process, knowledge of the mechanobiology of the periodontal ligament and the alveolar bone are essential. The periodontal ligament and alveolar bone make up a functional unit that undergoes robust changes during orthodontic tooth movement. Complex molecular signaling is responsible for converting mechanical stresses into biochemical events with a net result of bone apposition and/or bone resorption. Despite an improved understanding of mechanical and biochemical signaling mechanisms, it is largely unknown how mechanical stresses regulate the differentiation of stem/progenitor cells into osteoblast and osteoclast lineages. To advance orthodontics, it is crucial to gain a better understanding of osteoblast differentiation from mesenchymal stem/progenitor cells and osteoclastogenesis from the hematopoietic/monocyte lineage

Cosmic rays studied with a hybrid high school detector array

The LORUN/NAHSA system is a pathfinder for hybrid cosmic ray research combined with education and outreach in the field of astro-particle physics. Particle detectors and radio antennae were mainly setup by students and placed on public buildings. After fully digital data acquisition, coincidence detections were selected. Three candidate events confirmed a working prototype, which can be multiplied to extend further particle detector arrays on high schools.Comment: 10 pages, 6 figures. Nigl, A., Timmermans, C., Schellart, P., Kuijpers, J., Falcke, H., Horneffer, A., de Vos, C. M., Koopman, Y., Pepping, H. J., Schoonderbeek, G., Cosmic rays studied with a hybrid high school detector array, Europhysics News (EPN), Vol. 38, No. 5, accepted on 22/08/200

EU Ringonderzoek voedsel-I (2006) Bacteriologische detectie van Salmonella in rundergehakt

De Europese Nationale Referentie Laboratoria (NRLs) voor Salmonella hebben in een ringonderzoek hoge en lage concentraties Salmonella aangetoond in rundergehakt. Hiermee hebben ze laten zien dat ze voldoen aan de gestelde eisen. De Modified Semi-solid Rappaport Vassiliadis (MSRV), een analysemethode die veel gebruikt wordt voor Salmonella in dierenmest, bleek de beste methode voor het aantonen van Salmonella in rundergehakt. Vijfentwintig referentielaboratoria deden in september 2006 mee aan een ringonderzoek van het Communautair Referentie Laboratorium (CRL) voor Salmonella. Doel was in eerste instantie om na te gaan of de laboratoria Salmonella in gehakt goed konden aantonen. In tweede instantie werd ook onderzocht wat de beste analysemethode was voor het aantonen van Salmonella in rundergehakt. Ieder laboratorium kreeg een pakket toegestuurd met rundergehakt en 35 gelatine capsules met melkpoeder van verschillende besmettingsniveaus Salmonella. De laboratoria moesten volgens voorschrift gehakt en capsules samenvoegen en onderzoeken op de aanwezigheid van Salmonella. Voor het onderzoek gebruikten de laboratoria drie methoden: Rappaport Vassiliadis Soya broth (RVS), Mueller Kauffmann Tetrathionaat met novobiocine (MKTTn) en Modified Semi-solid Rappaport Vassiliadis (MSRV). De eerste twee methoden (RVS en MKKTn) staan bekend als internationaal voorgeschreven voor de analyse van Salmonella in levensmiddelen. De derde methode (MSRV) wordt gebruikt om Salmonella in dierlijke mest aan te tonen. Met een van de levensmiddelenmethoden (MKTTn) vonden alle laboratoria in slechts 88% van de monsters Salmonella. De methode voor dierlijke mest (MSRV) bleek de beste resultaten te geven. Hiermee vonden alle laboratoria in 99% van de besmette monsters Salmonella. De levensmiddelenmethode MKTTn blijkt dus niet de meest optimale methode te zijn voor het aantonen van Salmonella in rundergehakt.The European National Reference Laboratories (NRLs) for Salmonella were able to detect high and low levels of Salmonella in a ring trial using minced beef as matrix, thereby reaching the level of good performance. The Modified Semi-solid Rappaport Vassiliadis (MSRV), a method often used for the detection of Salmonella in animal faeces, turned out to be the best method for minced beef. This was one outcome of the inter-laboratory comparison study organized by the Community Reference Laboratory (CRL) for Salmonella on the detection of Salmonella spp. in a food matrix in September 2006. The first, and most important goal, was to see if the 25 participating laboratories in this study could detect Salmonella in minced beef. The second goal was to compare the different analysis methods for the detection of Salmonella in minced beef. Each laboratory received a package containing minced beef and 35 gelatin capsules containing different levels of Salmonella. According to the instructions, the laboratories spiked the meat with the capsules and tested those samples for the presence of Salmonella. The laboratories used three methods for running this test: Rappaport Vassiliadis Soya broth (RVS), Mueller Kauffmann Tetrathionate novobiocin broth (MKTTn) and Modified Semi-solid Rappaport Vassiliadis (MSRV). The first two methods are internationally prescribed for the detection of Salmonella in food, while the third (MSRV) is prescribed for the detection of Salmonella in veterinary faeces. All laboratories found Salmonella in just 88% of the samples using one of the food methods (MKTTn). The method for the veterinary samples, MSRV, gave the best results, with 99% of all laboratories detecting Salmonella in the spiked samples. The MKTTn food method is therefore not the optimal medium for the detection of Salmonella in minced beef.European CommissionLegislation Veterinaire et Zootechniqu

Index of Complexity, Outcome and Need scored on plaster and digital models

The aim of this study was to compare standard plaster models with their digital counterparts for the applicability of the Index of Complexity, Outcome, and Need (ICON). Generated study models of 30 randomly selected patients: 30 pre- (T0) and 30 post- (T1) treatment. Two examiners, calibrated in the ICON, scored the digital and plaster models. The overall ICON scores were evaluated for reliability and reproducibility using kappa statistics and reliability coefficients. The values for reliability of the total and weighted ICON scores were generally high for the T0 sample (range 0.83-0.95) but less high for the T1 sample (range 0.55-0.85). Differences in total ICON score between plaster and digital models resulted in mostly statistically insignificant values (P values ranging from 0.07 to 0.19), except for observer 1 in the T1 sample. No statistically different values were found for the total ICON score on either plaster or digital models. ICON scores performed on computer-based models appear to be as accurate and reliable as ICON scores on plaster model