Reference Plate Research Articles

Radiostereometric analysis using clinical radiographic views: Validation measuring total hip replacement wear.

Radiostereometric analysis (RSA) is a stereo X-ray technique used in clinical research studies to evaluate micro-motion and wear of orthopaedic implants within bone. While highly accurate and precise, its adoption has been limited due to technical requirements such as the need for implanted marker beads and radiograph view angles determined by a calibration cage. We propose a new technique that separates the calibration procedure from the patient examination, enabling clinical radiograph views to be used for RSA measurements. The concept of a reference plate was adapted to establish the link between calibration procedure and patient examination procedure for cassette radiography, which may not be necessary for digital radiography. A hip wear phantom was used to validate this technique by comparing the error and repeatability of the novel procedure with that of conventional RSA. Femoral head penetration was measured versus the acetabular cup (head/cup) and marker beads in the acetabular liner (head/liner). Conventional RSA had lower inferior-superior average error (p = 0.03 for head/cup) while the modified RSA had lower anterior-posterior average error (p = 0.01). Average error was greater but not significantly so for the medial-lateral (p = 0.06) and 3D (p = 0.97) measurements. The head/liner method had lower average errors (p < 0.0001) for both procedures, but did not affect repeatability, which was similar between techniques. The novel procedure's average error and repeatability was therefore, similar to conventional RSA. This new technique could be applied to any joint with two clinical radiograph view angles pending further validation in subjects. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:1521-1528, 2016.

Anatomical and biomechanical evaluation of an intramedullary nail for fractures of proximal humerus fractures based on tuberosity fixation

BackgroundFor unstable proximal humerus fractures, both plates and nails may be recommended. We introduce an anterograde nail designed for the treatment of 3- and 4-parts proximal humerus fractures. The aim of this study is to compare the biomechanics of this nail versus a plate and then to analyze the relationships of the screws with the axillary nerve. Our working hypotheses are as follows: (1) this nail is biomechanically equal or better to the reference plate and (2) it does not endanger the axillary nerve. MethodsBiomechanical study: using 40 sawbones, a reproducible 4-part fracture was created and fixed first with an angle-stable plate for proximal humeral fracture, then fixed with the nail using 2 posterior screws. All specimens were mounted in a custom testing apparatus. Two trails were performed needing each time 5 “normal” and 5 “osteoporotic” bones. Anatomical studyOn 20 unpaired shoulders, a nail was inserted with all screws through a superior approach (deltoid split approach). Dissection of all shoulders was done to identify the axillary nerve. The distance between each screw and the axillary nerve or its branches was measured. FindingsThe proximal humerus nail demonstrated higher values than locking plate for both stiffness and load to failure. The failure mode differs in function of the type of osteosynthesis.The lowest distance between a screw and the axillary nerve was 20.13mm. InterpretationsWe introduce a biomechanically efficient nail without increased neurological risks to improve the pullout strength of the screws to provide more secure fixation of proximal humeral fractures. Level of evidenceBasic Science Study, Anatomic Cadaver Study.

Fluorescence reference plate for UV illumination using quantum dots.

Many image acquisition methods of nucleic acids still depend on UV illumination, especially after the electrophoresis when determining the size of the target DNA. Therefore the quality of the UV illuminator in the gel documentation system, and the comparison of the fluorescence detected are crucial. This paper presents a fluorescence standard reference plate using quantum dots compared to the conventional method where an agarose gel containing ethidium bromide is loaded with standard samples. The fluorescence standard reference plate consists of chambers filled with commercially available quantum dots such as phosphor dots. The chamber is made by thermally attaching nylon and polyester, the former on the inside and the latter on the outside, for increased stability. The images of the proposed reference plate were captured more than 2 months in regular intervals. The intensity analysis of the images shows that the proposed reference plate delivers stable fluorescence over a long term period. The proposed reference plate can be utilized to compare the performance of various UV illuminators, or to set a standard fluorescence point for certain analyses.

Fluorescence reference plate for UV illumination using quantum dots.

Many image acquisition methods of nucleic acids still depend on UV illumination, especially after the electrophoresis when determining the size of the target DNA. Therefore the quality of the UV illuminator in the gel documentation system, and the comparison of the fluorescence detected are crucial. This paper presents a fluorescence standard reference plate using quantum dots compared to the conventional method where an agarose gel containing ethidium bromide is loaded with standard samples. The fluorescence standard reference plate consists of chambers filled with commercially available quantum dots such as phosphor dots. The chamber is made by thermally attaching nylon and polyester, the former on the inside and the latter on the outside, for increased stability. The images of the proposed reference plate were captured more than 2 months in regular intervals. The intensity analysis of the images shows that the proposed reference plate delivers stable fluorescence over a long term period. The proposed reference plate can be utilized to compare the performance of various UV illuminators, or to set a standard fluorescence point for certain analyses.

Measured Performance and Stability Analysis of Large-Scale Reinforced Model Embankments at Different Moisture Contents

This paper describes construction and instrumentation of two 1.65-m high reinforced embankment models that were tested at two different gravitational water contents (GWC) on the dry and wet sides of the optimum moisture content (OMC); i.e. OMC−2 % and OMC+2 %. The embankment models were constructed using a clayey sand that was reinforced with four layers of instrumented geotextile with a uniform vertical spacing of 300 mm. Each model embankment was subjected to a line surcharge load (strip footing) near its crest until failure. The magnitudes of GWC, earth pressure, geotextile strains, footing settlement and embankment deformations were measured using EC-5 sensors, earth pressure cells, wire potentiometers, linear variable deferential transformers and reference plates, respectively during the construction and loading phases of each test. The GWC values in each model embankment were measured using EC-5 sensors and the oven drying method to ensure that they were close to the target values. Slope stability analysis was carried out to study the equilibrium of embankment models and to validate the predicted bearing capacity and factor of safety results against the experimental data. Results of this study show that the embankment model constructed on the dry side of OMC (i.e. OMC−2 %) had a 10 % greater serviceability failure load than the model built at OMC+2 %. Meanwhile, stability analysis results indicate that the bearing capacity of an unreinforced model embankment at OMC−2 % would be 72 % lower than that of the corresponding reinforced model. It is also found that compaction-induced energy could increase the earth pressure within the embankment by up to 70 % of the vertical stress in the soil mass due to gravity.

Dew harvesting efficiency of four species of cacti

Four species of cacti were chosen for this study: Copiapoa cinerea var. haseltoniana, Ferocactus wislizenii, Mammillaria columbiana subsp. yucatanensis and Parodia mammulosa. It has been reported that dew condenses on the spines of C. cinerea and that it does not on the spines of F. wislizenii, and our preliminary observations of M. columbiana and P. mammulosa revealed a potential for collecting dew water. This study found all four cacti to harvest dew on their stems and spines (albeit rarely on the spines of F. wislizenii). Dew harvesting experiments were carried out in the UK, recording an increase in cacti mass on dewy nights. By applying a ranking relative to a polymethyl methacrylate (Plexiglas) reference plate located nearby, it was found that C. cinerea collected the most airborne moisture followed by M. columbiana, P. mammulosa and F. wislizenii respectively, with mean efficiency ratio with respect to the Plexiglas reference of 3.48 ± 0.5, 2.44 ± 0.06, 1.81 ± 0.14 and 1.27 ± 0.49 on observed dewy nights. A maximum yield of normalized performance of 0.72 ± 0.006 l/m−2 on one dewy night was recorded for C. cinerea. Removing the spines from M. columbiana was found to significantly decrease its dew harvesting efficiency. The spines of three of the species were found to be hydrophilic in nature, while F. wislizenii was hydrophobic; the stems of all four species were hydrophilic. The results of this study could be translated into designing a biomimetic water collecting device that utilizes cactus spines and their microstructures.

Reduction of Distance Drift with Temperature in Uniaxial Laser Rangefinder by Using Multiecho Sensing

&lt;div class=""abs_img""&gt;&lt;img src=""[disp_template_path]/JRM/abst-image/00270001/08.jpg"" width=""300"" /&gt;Uniaxial laser rangefinder&lt;/div&gt; To expand the range of activities by unmanned aerial vehicles (UAVs), whose use at disaster sites and other dangerous locations has raised high expectations, UAVs must be capable of several functions, e.g., flight both indoor and outdoor environments. This requires making the airframe and major sensors as compact and light-weight as possible. To do so, we are developing uniaxial laser rangefinders to replace conventional scanning laser rangefinders. One developmental approach to uniaxial laser rangefinders and results regarding their validity are reported in this paper. Using a simulated model -- a modified scanning laser rangefinder -- we discuss the effectiveness of our approach. Specifically, this is to reduce the range drift due to heat, for which we propose using a multiecho to measure two echoes from a reference plate whose distance is known and that is placed outside of the sensor, and the target object, instead using the internal reference plate used in conventional two-dimensional scanning laser rangefinders. We also report the results of experiments verifying its validity. &lt;/span&gt;

Similitudes for the structural response of flexural plates

This article presents an investigation into exact and distorted similitudes and the related scaling laws for the analysis of the dynamic response of rectangular flexural plates. The response of a given model in similitude is determined from a generalization of the modal approach, which allows the use the mode shapes and natural frequencies in order to establish scaling laws. Analytical models of simply supported rectangular plates are used to produce both the original and distorted model responses. Some highlights about the distribution of the natural frequencies, the forced response and the energy response are given. The results show that, with the proposed methodology, it is possible to reproduce with good confidence the response of the reference plate, even if distorted models are used.

S1110105 円筒表面形状のナノレベル測定を目指した広視野レーザ干渉計の開発 : 円筒面上の微小痕観察による性能評価

In a previous study, a novel method for observation of cylindrical surfaces was developed with a laser microscope. With this laser microscope having a wide field of view, cylindrical surfaces can be observed by scanning the focused laser light along the bus direction and rotating the cylinder. However, there is a trade-off relationship between the field of view and the resolution in the depth direction, the resolution of laser microscope with wide field of view becomes low. In this study, we have supplemented the low resolution in the depth direction by introducing a reference plate. To clarify how the resolution in the depth direction is improved, small indentation marks were prepared on the cylindrical surface and were observed with the laser microscope. It can be said, by comparison with stylus profilometer that there were measurement errors less than 1μm. In addition, the cylindrical lens for which there have been almost no practical measurement method was also measured. The three-dimensional shape of the cylindrical lens was analyzed from the observation result and displayed in a computer screen.

Director reorientation in a nematic liquid crystal with a photosensitive layer.

We use a molecular-motor model previously proposed for a nematic cell with an azo-dye monolayer to calculate the director orientation when light is normally impinged on the cell. We consider an initial planar configuration for which one of the surrounding plates, which we call the reference plate, is submitted to a hard-anchoring boundary condition. The other confining plate has a coating monolayer of azo-dye molecules such that the change of the orientation of azo-dye isomers, due to light, causes changes in the nematic director. The boundary conditions on both plates along with the optical field determine the director configuration in the bulk. The existence of periodic solutions for the density of isomers in trans and cis states, corresponding to weak optical fields, has been discussed in the literature. Using a similar approach, we find an approximate expression for the density of isomers, written in terms of the director angle, which allows us to close the equation for the director configuration on the boundary having a photosensitive plate. We decouple the director's angle and the isomer densities by assuming extremely different temporal time scales between them. We show for a given sample that switching times inversely depend on the trans-cis transition rate of photoexcitation whereas relaxation times do not depend on it. On the other hand, switching and relaxation times linearly depend on effective surface viscosity values. Our model allows us to estimate surface viscosity values.

Experimental study of sound radiation by plates containing circular indentations of power-law profile

In this paper, the results of the first experimental investigation into sound radiation of rectangular plates containing tapered indentations of power-law profile are reported. Such tapered indentations materialise two-dimensional acoustic black holes for flexural waves in plates that result in absorption of a large proportion of the incident wave energy. A multi-indentation plate was compared to a plain reference plate of the same dimensions, and the radiated sound power was determined according to ISO 3744. It was demonstrated that not only do such multiple indentations provide substantial reduction in the damping of flexural vibrations within the plates, but also cause a substantial reduction in the radiated sound power. As the amplitudes of the flexural vibrations of a plate are directly linked to the amplitudes of radiated sound from the same plate, this paper also considers the effect of redistribution of the amplitude of the plate’s response due to the presence of acoustic black holes on the amplitudes of the radiated sound. The results show that, in spite of some increase in the amplitudes of the displacements at the centres of black holes (circular indentations), the overall reduction of vibration response over the plate is large enough to cause a substantial reduction in the resulting sound radiation from plates containing indentations of power-law profile.

Mechanical Properties of a Metal Sandwich Panel Manufactured Using Longitudinally Laminated Forming Tools

Sandwich panel structures are increasingly used in applications where the most important demands are the weight saving and long service life. Utilizing sandwich panels, extremely light-weight, stiff and robust structures can be manufactured. In this study, sandwich panels were produced by specially designed cost-effective forming tools. Various kind of test materials were used for corrugated cores and skin plates: conventional low-carbon steel grade EN 10130 and ferritic stainless steel grade 1.4509 with plate thicknesses of 0.6 and 0.75 mm. A common S355 structural steel was used as a reference for bending strength comparison.For measuring the stiffness, MTS tensile and fatigue testing machine was selected to determine the bending resistance of the sandwich panels. The bending force, needed for yielding and fracture, related to the bending length and intensity was compared with the results from bending of the reference plates. Results showed that the bending force of the panels is significantly higher than that of a plate having similar intensity. The best results were obtained with the stainless steel (SS) panel that had 27% higher bending force at the yield point than 5 mm thick S355 plate having 3 times larger intensity. The carbon steel panel was approximately 40% weaker than the SS-panel and both panel types lost strength when loading direction was changed from transverse to 45 degree and further to 90 degree load (longitudinal).

Light-Induced Instabilities in Photo-Oriented Liquid Crystal Cells

In a planar liquid crystal sample sandwiched between a photosensitive and a reference plate instabilities occurred, when the cell was illuminated from the reference side. The instabilities were induced both by polarized white light source and monochromatic laser beams. Static and dynamic regimes were found; for laser irradiation dynamic instability was found only in a range of polarization directions. A model, developed for monochromatic excitation, predicts that at certain thicknesses dynamic instability is forbidden. Experiments on a wedge-like cell confirmed this conclusion.

Assessment of thermal sensitivity in rats using the thermal place preference test

Thermal sensitivity is an essential characteristic of some painful states, including oxaliplatin-induced neuropathy. The thermal place preference test (TPPT) was designed to finely assess thermal sensitivity in rodents. The TPPT monitors the time spent by unrestrained rodents on a test plate at fixed temperatures (5-50°C) compared with an adjacent reference plate at a neutral temperature (25°C). Here, we report the results of a study designed (i) to validate the optimal methodological parameters for measuring thermal sensitivity in rats, (ii) to assess the thermal sensitivity of healthy rats and animal models of pain and (iii) to explore the pharmacological effects of analgesic drugs. The most reproducible conditions occurred when the TPPT was performed in the morning and in the dark for 3 min with the reference plate set to 25°C. The temperature preferences of healthy rats were more than 17°C and less than 40°C. When compared with control animals, oxaliplatin-treated rats showed thermal hypersensitivity at 12, 20 and 35°C, and carrageenan-treated rats showed thermal hypersensitivity at 15 and 45°C. Duloxetine (2.5 mg/kg, intraperitoneal) reversed oxaliplatin-induced cold hypersensitivity (20°C) and morphine (1 mg/kg, intravenous) reversed carrageenan-induced heat hypersensitivity (45°C). We conclude that the TPPT enables a fine-grained assessment of thermal sensitivity that is relevant to the pathophysiological exploration of animal pain models and to the pharmacological assessment of analgesic drugs.

A new general approach for solving the self-calibration problem on large area 2D ultra-precision coordinate measurement machines

The manufacturing of flat panel displays requires a number of photomasks for the placement of pixel patterns and supporting transistor arrays. For large area photomasks, dedicated ultra-precision writers have been developed for the production of these chromium patterns on glass or quartz plates. The dimensional tolerances in X and Y for absolute pattern placement on these plates, with areas measured in square meters, are in the range of 200–300 nm (3σ). To verify these photomasks, 2D ultra-precision coordinate measurement machines are used having even tighter tolerance requirements. This paper will present how the world standard metrology tool used for verifying large masks, the Micronic Mydata MMS15000, is calibrated without any other references than the wavelength of the interferometers in an extremely well-controlled temperature environment. This process is called self-calibration and is the only way to calibrate the metrology tool, as no square-meter-sized large area 2D traceable artifact is available. The only parameter that cannot be found using self-calibration is the absolute length scale. To make the MMS15000 traceable, a 1D reference rod, calibrated at a national metrology lab, is used. The reference plates used in the calibration of the MMS15000 may have sizes up to 1 m2 and a weight of 50 kg. Therefore, standard methods for self-calibration on a small scale with exact placements cannot be used in the large area case. A new, more general method had to be developed for the purpose of calibrating the MMS15000. Using this method, it is possible to calibrate the measurement tool down to an uncertainty level of <90 nm (3σ) over an area of (0.8 × 0.8) m2. The method used, which is based on the concept of iteration, does not introduce any more noise than the random noise introduced by the measurements, resulting in the lowest possible noise level that can be achieved by any self-calibration method.

Measurement of the complex transmittance of large optical elements with Ptychographical Iterative Engine

Wavefront control is a significant parameter in inertial confinement fusion (ICF). The complex transmittance of large optical elements which are often used in ICF is obtained by computing the phase difference of the illuminating and transmitting fields using Ptychographical Iterative Engine (PIE). This can accurately and effectively measure the transmittance of large optical elements with irregular surface profiles, which are otherwise not measurable using commonly used interferometric techniques due to a lack of standard reference plate. Experiments are done with a Continue Phase Plate (CPP) to illustrate the feasibility of this method.

A novel method based on image processing to visualize clusters in a rectangular circulating fluidized bed riser

A new image processing method based on image calibration has been developed to visualize clusters in a Plexiglas rectangular circulating fluidized bed (CFB) riser at the fully developed region. A high speed video camera is adopted with FCC particles of 67μm used as the bed material. In order to make sure day-to-day shooting images reliable and comparable under the same light illumination during the whole shooting period, a reference plate is made first to verify the light illumination consistency. After the verification, the relationship between solids holdup and image grayscale is calibrated in the same riser with both calibration curve and equation obtained. With given solids holdup thresholds increasing from 0.01 to 0.1, cluster size clearly decreases while cluster solids holdup increases by transforming gray images into binary ones. The variation of cluster profiles with different thresholds also reveals that there is a solids holdup gradient inside the cluster with a lower value at the surface and a higher one in the core. The change in dense phase holdup or cluster population with operating conditions is indicated by the variation of the black area under given solids holdup thresholds, which compare well with the well-known fact reported by many previous studies: higher Gs and lower Ug are beneficial for clusters with higher solids holdup to form, while lower Gs and higher Ug induce clusters to breakup. This consistency proves that the image processing method developed in the present study is effective and very useful.

Laser-induced instabilities in liquid crystal cells with a photosensitive substrate

Liquid crystal layers sandwiched between a reference plate and a photosensitive substrate were investigated. We focused on the reverse geometry, where the cell was illuminated by a laser beam from the reference side. In planar cells both static and dynamic instabilities occurred, depending on the angle between the laser polarization and the director orientation on the reference plate. In cells where the molecules were aligned along the normal of the reference plate, a dynamic pattern was observed at all angles of polarization. A simple model based on a photoinduced surface torque accounts for the findings. Light scattering studies revealed some basic properties of the instabilities.

参照平板の横シフトおよび逐次二点法を用いた真直度輪郭測定

This paper deals with invention of a new measurement principle for straightness profile measuring instrument based on numerical software datum. The novel sequential two-point method was realized using a twin heads displacement sensor and a shifting reference plate in the lateral direction. Utilizing a precise level meter for correction of the reference plate slope, a long distance straightness profile can be measured in an extrapolative way. Uncertainty analysis on designed specifications of the measuring instrument assured its high accuracy and practicality. The experimental variation of straightness profiles measured by a developed measurement system was in a good agreement with the numerical simulation.

レーザスポット走査型干渉計の開発

Small lenses are one of the most important elements in digital devices such as mobile phones with cameras. In order to minimize the machining error of aspheric lens molds with high form accuracy, on-machine measurement of the lens mold shape is important. However, they require large field of view of mm order in diameter, robustness against vibrational noises from environment, short tact time, and compact body for on-machine measurements. We developed a Fizeau-type interferometer with wide field of view. The interferometer has small laser spot of 2.5μm in diameter, which scans over the 10mm x 8mm of observation area. With the use of transparent reference plates set over the concave of the lens mold, fringe patterns of lens mold with about 1.5mm in diameter was successfully observed in 80 seconds. This interferometer is also designed in a compact size.