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

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

A burst from the direction of UZ Fornacis with XMM-Newton

The XMM-Newton pointing towards the magnetic cataclysmic variable UZ For finds the source to be a factor > 10^3 fainter than previous EXOSAT and ROSAT observations. The source was not detected for the majority of a 22 ksec exposure with the EPIC cameras, suggesting that the accretion rate either decreased, or stopped altogether. However a 1.1 ksec burst was detected from UZ For during the observation. Spectral fits favour optically thin, kT = 4.4 keV thermal emission. Detection of the burst by the on-board Optical Monitor indicates that this was most probably an accretion event. The 0.1-10 keV luminosity of 2.1 x 10^30 erg/s is typical for accretion shock emission from high state polars and would result from the potential energy release of ~ 10^16 g of gas. There is no significant soft excess due to reprocessing in the white dwarf atmosphere.Comment: 7 pages, 2 postscript figures, ApJL, in pres

ORFEUS II Far-UV Spectroscopy of AM Herculis

Six high-resolution (\lambda/\Delta\lambda ~ 3000) far-UV (\lambda\lambda = 910-1210 \AA) spectra of the magnetic cataclysmic variable AM Herculis were acquired in 1996 November during the flight of the ORFEUS-SPAS II mission. AM Her was in a high optical state at the time of the observations, and the spectra reveal emission lines of O VI \lambda\lambda 1032, 1038, C III \lambda 977, \lambda 1176, and He II \lambda 1085 superposed on a nearly flat continuum. Continuum flux variations can be described as per Gansicke et al. by a ~ 20 kK white dwarf with a ~ 37 kK hot spot covering a fraction f~0.15 of the surface of the white dwarf, but we caution that the expected Lyman absorption lines are not detected. The O VI emission lines have narrow and broad component structure similar to that of the optical emission lines, with radial velocities consistent with an origin in the irradiated face of the secondary and the accretion funnel, respectively. The density of the narrow- and broad-line regions is n_{nlr} ~ 3\times 10^{10} cm^{-3} and n_{blr} ~ 1\times 10^{12} cm^{-3}, respectively, yet the narrow-line region is optically thick in the O VI line and the broad-line region is optically thin; apparently, the velocity shear in the broad-line region allows the O VI photons to escape, rendering the gas effectively optically thin. Unexplained are the orbital phase variations of the emission-line fluxes.Comment: 15 pages, 6 Postscript figures; LaTeX format, uses aaspp4.sty; table2.tex included separately because it must be printed sideways - see instructions in the file; accepted on April 17, 1998 for publication in The Astrophysical Journa

Cyclotron modeling phase-resolved infrared spectroscopy of polars I: EF Eridani

We present phase-resolved low resolution infrared spectra of the polar EF Eridani obtained over a period of 2 years with SPEX on the IRTF. The spectra, covering the wavelength range 0.8 to 2.4 microns, are dominated by cyclotron emission at all phases. We use a ``Constant Lambda'' prescription to attempt to model the changing cyclotron features seen in the spectra. A single cyclotron emission component with B = 12.6 MG, and a plasma temperature of kT = 5.0 keV, does a reasonable job in matching the features seen in the H and K bands, but fails to completely reproduce the morphology shortward of 1.6 microns. We find that a two component model, where both components have similar properties, but whose contributions differ with viewing geometry, provides an excellent fit to the data. We discuss the implications of our models and compare them with previously published results. In addition, we show that a cyclotron model with similar properties to those used for modeling the infrared spectra, but with a field strength of B = 115 MG, can explain the GALEX observations of EF Eri.Comment: 25 pages, 5 figures, to appear in Ap

Why do some intermediate polars show soft X-ray emission? A survey of XMM-Newton spectra

We make a systematic analysis of the XMM-Newton X-ray spectra of intermediate polars (IPs) and find that, contrary to the traditional picture, most show a soft blackbody component. We compare the results with those from AM Her stars and deduce that the blackbody emission arises from reprocessing of hard X-rays, rather than from the blobby accretion sometimes seen in AM Hers. Whether an IP shows a blackbody component appears to depend primarily on geometric factors: a blackbody is not seen in those that have accretion footprints that are always obscured by accretion curtains or are only visible when foreshortened on the white-dwarf limb. Thus we argue against previous suggestions that the blackbody emission characterises a separate sub-group of IPs which are more akin to AM Hers, and develop a unified picture of the blackbody emission in these stars.Comment: 9 pages, 6 figures. Accepted for publication in Ap

Diabetes quality management in Dutch care groups and outpatient clinics:A cross-sectional study

BACKGROUND: In recent years, most Dutch general practitioners started working under the umbrella of diabetes care groups, responsible for the organisation and coordination of diabetes care. The quality management of these new organisations receives growing interest, although its association with quality of diabetes care is yet unclear. The best way to measure quality management is unknown and it has not yet been studied at the level of outpatient clinics or care groups. We aimed to assess quality management of type 2 diabetes care in care groups and outpatient clinics. RESULTS: Quality management was measured with online questionnaires, containing six domains (see below). They were divided into 28 subdomains, with 59 (care groups) and 57 (outpatient clinics) questions respectively. The mean score of the domains reflects the overall score (0-100%) of an organisation. Two quality managers of all Dutch care groups and outpatient clinics were invited to fill out the questionnaire. Sixty care groups (response rate 61.9%) showed a mean score of 59.6% (CI 57.1-62.1%). The average score in 52 outpatient clinics (response rate 50.0%) was 61.9% (CI 57.5-66.8%). Mean scores on the six domains for care groups and outpatient clinics respectively were: ‘organisation of care’ 71.9% (CI 68.8-74.9%), 76.8% (CI 72.8-80.7%); ‘multidisciplinary teamwork’ 67.1% (CI 62.4-71.9%), 71.5% (CI 65.3-77.8%); ‘patient centeredness’ 46.7% (CI 42.6-50.7%), 62.5% (CI 57.7-67.2%); ‘performance management’ 63.3% (CI 61.2-65.3%), 50.9% (CI 44.2-57.5%); ‘quality improvement policy’ 52.6% (CI 49.2-56.1%), 50.9% (CI 44.6-57.3%); and ‘management strategies’ 56.0% (CI 51.4-60.7%), 59.0% (CI 52.8-65.2%). On subdomains, care groups scored highest on ‘care program’ (83.3%) and ‘measured outcomes’ (98.3%) and lowest on ‘patient safety’ (15.1%) and ‘patient involvement’ (17.7%). Outpatient clinics scored high on the presence of a ‘diabetic foot team’ (81.6%) and the support in ‘self-management’ (81.0%) and low on ‘patient involvement’ (26.8%) and ‘inspection of medical file’ (28.0%). CONCLUSIONS: This nationwide assessment reveals that the level of quality management in diabetes care varies between several subdomains in both diabetes care groups and outpatient clinics

The Far-Ultraviolet Spectrum and Short Timescale Variability of AM Herculis from Observations with the Hopkins Ultraviolet Telescope

Using the Hopkins Ultraviolet Telescope (HUT), we have obtained 850-1850 angstrom spectra of the magnetic cataclysmic variable star AM Her in the high state. These observations provide high time resolution spectra of AM Her in the FUV and sample much of the orbital period of the system. The spectra are not well-modelled in terms of simple white dwarf (WD) atmospheres, especially at wavelengths shortward of Lyman alpha. The continuum flux changes by a factor of 2 near the Lyman limit as a function of orbital phase; the peak fluxes are observed near magnetic phase 0.6 when the accreting pole of the WD is most clearly visible. The spectrum of the hotspot can be modelled in terms of a 100 000 K WD atmosphere covering 2% of the WD surface. The high time resolution of the HUT data allows an analysis of the short term variability and shows the UV luminosity to change by as much as 50% on timescales as short as 10 s. This rapid variability is shown to be inconsistent with the clumpy accretion model proposed to account for the soft X-ray excess in polars. We see an increase in narrow line emission during these flares when the heated face of the secondary is in view. The He II narrow line flux is partially eclipsed at secondary conjunction, implying that the inclination of the system is greater than 45 degrees. We also present results from models of the heated face of the secondary. These models show that reprocessing on the face of the secondary star of X-ray/EUV emission from the accretion region near the WD can account for the intensities and kinematics of most of the narrow line components observed.Comment: 19 pp., 12 fig., 3 tbl. To appear in The Astrophysical Journal. Also available at http://greeley.pha.jhu.edu/papers/amherpp.ps.g