Measure Minute Changes Research Articles

On the difficulties of obtaining absolute transit depths with HST WFC3: KELT-11 b, an example

ABSTRACT The study of exoplanetary atmospheres with low-resolution transmission spectroscopy relies on measuring minute changes in the transit depth with wavelength and a number of ground- and space-based instruments have been used to characterize exoplanets in different spectral bands. For the last decade, these instruments have each only probed a narrow spectral region, which has motivated the community to combine observations from different instruments in order to achieve a broader wavelength coverage. By analysing Hubble Space Telescope (HST) Wide Field Camera 3 (WFC3) data of KELT-11 b, we once again show the risks of following this now conventional approach. We demonstrate that changes in the reduction or analysis method can lead to drastic differences in the mean transit depth and that combining this with additional data can lead to discrepant interpretations of the atmospheric composition. With the launch of JWST, and its many available instruments and modes, observers may be tempted to combine data sets at longer wavelengths (e.g. NIRSpec – Near Infrared Spectrometer) with those from HST STIS (Space Telescope Imaging Spectrograph) or WFC3 without the consideration of offsets or other incompatibilities. Given the obvious potential issues, we caution against such an approach and encourage the community to thoroughly address the issue of data incompatibility instead of adhering to a de facto assumption of compatibility.

Thickness measurements of a Cr coating deposited on Zr-Nb alloy plates using an ECT pancake sensor

Zr-Nb alloy have been widely used as fuel rods in nuclear power plants. However, from the Fukushima nuclear accident, the weakness of the rod was revealed under harsh conditions, and research on the safety of these types of rods was conducted after the disaster. The method of depositing chromium onto the existing Zr-Nb alloy fuel rods is being considered as a means by which to compensate for the weakness of Zr-Nb alloy rods because chromium is strong against oxidation at high temperatures and has high strength. In order to secure these advantages, it is important to maintain the Cr thickness of the rods and properly inspect the rods before and during their use in power generation. Eddy current testing is a typical means of evaluating the thickness of thin metals and detecting surface defects. Depending on the size and shape of the inspected object, various eddy current sensors can be applied. In particular, because pancake sensors can be manufactured in very small sizes, they can be used for inspections even in narrow spaces, such as a nuclear fuel assembly.In this study, an eddy current technique was developed to confirm the feasibility of Cr coating thickness evaluations. After determining the design parameters of the pancake sensor by means of a FEM simulation, a FPCB pancake sensor was manufactured and the optimal frequency was selected by measuring minute changes in the Cr-coating thickness using the developed sensor.

Photochemical method for removing methane interference for improved gas analysis

Abstract. The development of laser spectroscopy has made it possible to measure minute changes in the concentrations of trace gases and their isotopic analogs. These single or even multiply substituted species occur at ratios from percent to below parts per million and contain important information concerning trace gas sources and transformations. Due to their low abundance, minimizing spectral interference from other gases in a mixture is essential. Options including traps and membranes are available to remove many specific impurities. Methods for removing CH4, however, are extremely limited as methane has low reactivity and adsorbs poorly to most materials. Here we demonstrate a novel method for CH4 removal via chlorine-initiated oxidation. Our motivation in developing the technique was to overcome methane interference in measurements of N2O isotopic analogs when using a cavity ring-down spectrometer. We describe the design and validation of a proof-of-concept device and a kinetic model to predict the dependence of the methane removal efficiency on the methane concentration [CH4], chlorine photolysis rate JCl2, chlorine concentration [Cl2] and residence time tR. The model was validated by comparison to experimental data and then used to predict the possible formation of troublesome side products and by-products including CCl4 and HCl. The removal of methane could be maintained with a peak removal efficiency >98 % for ambient levels of methane at a flow rate of 7.5 mL min−1 with [Cl2] at 50 ppm. These tests show that our method is a viable option for continuous methane scrubbing. Additional measures may be needed to avoid complications due to the introduction of Cl2 and formation of HCl. Note that the method will also oxidize most other common volatile organic compounds. The system was tested in combination with a cavity ring-down methane spectrometer, and the developed method was shown to be successful at removing methane interference.

Reducing Measurement Error in Capacitive Readout Circuits Based on Weakly Coupled Resonators

A recently proposed method for measuring minute changes in capacitance based on weakly coupled resonators has been examined for its sensitivity with respect to unwanted resonant frequency changes. This sensitivity has been compared with the conventional capacitance measurement method based on the capacitance to frequency conversion. It has been analytically shown that both sensitivities are nearly equal but with opposite signs. This has led to a new hybrid capacitance measurement method to reduce the error by at least an order of magnitude. The analytical results have been validated by various simulations and experimental measurements.

Proposal of In-process Measurement for Micro-stereolithography Using Surface Plasmon Resonance

There is strong demand for the development of micro-manufacturing techniques to realize three-dimensional micro-structures. One of the important techniques is micro-stereolithography, which solidifies photopolymer resin using optical energy. Regarding the manufacturing accuracy of micro-stereolithography, structural errors should be improved; however, they are influenced by optical conditions, the material conditions of resins, and so on. Because dimensions and shapes can be evaluated only after completing all of the manufacturing processes, in-process measurement is useful for improving manufacturing accuracy. The solidified photopolymer resin changes its refractive index as little as 0.04, compared with the case before solidification. In this study, the surface plasmon resonance (SPR) is proposed to measure minute changes of the refractive index. The condition required to excite SPR is highly sensitive to both the refractive index of environmental materials and the thickness of (and materials used in) the plasmonic substrate. In this paper, the novel method and fundamental properties are discussed.

Centre of Pressure Detection and Analysis with a High-resolution and Low-cost Smart Insole

This study aims to compare the accuracy of a pair of novel low-cost insoles with that of the proven standard Kistler force plate. The correlation of both devices had a r2 value of 0.942 and 0.946 for COPx and COPy respectively during dynamic tests conducted to measure macroscopic changes of the COP. Fractal dimension analysis was conducted to measure minute changes during quiet standing on solid surface and on foam, with both insoles and the force plate showing the same trend where the fractal values of standing on foam were significantly higher than that of standing on a solid surface. Further validation was done to compare the results with the mean velocities of the measured data that showed identical significant trends as the fractal dimension analysis.

Oscillating wave sensors based on ultrahigh-order modes in symmetric metal-clad optical waveguides

An oscillating wave sensor that uses ultrahigh-order modes in symmetric metal-clad waveguide with submillimeter scale is investigated to measure minute changes in refractive index (RI) of aqueous solution. In the proposed sensor, the sample acts as the guiding layer where oscillating wave propagates. Owing to the concentrated power in the sensing region and the use of the very sensitive ultrahigh-order modes, it is demonstrated both theoretically and experimentally that its sensitivity is enhanced by one order of magnitude than that of evanescent wave sensor. The sensor also provides a wide detection range of RI from 1 to 2.0 or higher.

Sensing minute changes in biological cell monolayers with THz differential time-domain spectroscopy

We used terahertz differential time-domain spectroscopy (THz-DTDS) to measure minute changes of bovine lung microvessel endothelial cells (BLMVEC) in response to vascular endothelial growth factor (VEGF). These changes were reflected by alterations in THz wave attenuations and THz dielectric properties of the treated cells. The VEGF-induced THz attenuations of cell monolayers correlated well with changes in transendothelial resistance, as measured using electric cell-substrate impedance sensing (ECIS). However, the morphological differences that gave rise to these changes were not observed with standard optical phase contrast microscopy. We conclude that THz-DTDS is a highly sensitive, non-invasive, powerful new tool to measure minute changes in the morphology of live, cultured cell monolayers. This method enables spectroscopic investigations of cells in the THz band, providing information unavailable through other conventional methods such as optical phase contrast microscopy and ECIS.

Real-Time Monitoring of Morphological Changes in Living Cells by Electronic Cell Sensor Arrays: An Approach To Study G Protein-Coupled Receptors

G protein-coupled receptors (GPCRs) constitute important targets for drug discovery against a wide range of ailments including cancer, inflammatory, and cardiovascular diseases. Efforts are underway to screen selective modulators of GPCRs and also to deorphanize GPCRs with unidentified natural ligands. Most GPCR-based cellular screens depend on labeling or recombinant expression of receptor or reporter proteins, which may not capture the true physiology or pharmacology of the GPCRs. In this paper, we describe a noninvasive and label-free assay for GPCRs that can be used with both engineered and nonengineered cell lines. The assay is based on using cell-electrode impedance to measure minute changes in cellular morphology as a result of ligand-dependent GPCR activation. We have used this technology to assay the functional activation of GPCRs coupled to different signaling pathways and have compared it to standard assays. We have used pharmacological modulators of GPCR signaling pathways to demonstrate the specificity of impedance-based measurements. Our data indicate that cell-electrode impedance measurements offer a convenient, sensitive, and quantitative method for assessing GPCR function. Moreover, the noninvasive nature of the readout offers the added advantage of performing multiple treatments in the same well to study events such as desensitization and receptor cross-talk.

Elasticity imaging of atheroma with transcutaneous ultrasound both in longitudinal-axis and short-axis planes

This paper describes a noninvasive method for evaluating regional viscoelasticity of the arterial wall in which a novel method is applied to measure minute changes in wall thickness caused by the change in internal pressure. (1) By comparing the pathological findings with the elasticity distribution, statistical parameters for lipid and a mixture of smooth muscle and collagen fibers can be determined. By applying the method to the common carotid arteries, thin collagen fiber was clarified and soft inclusion of lipid in plaque was detected. (2) A new beam steering method was proposed to apply the above method to the plane, which is perpendicular to the axis of the artery. (3) For improvement of classification of tissue, a method was proposed to measure viscosity by generating the change in internal pressure using the external actuation from the skin surface, namely remote actuation. These methods offer the potential for detection of plaque vulnerability in a clinical setting.

To the bottom of the heart: cloacal movement as an index of cardiac frequency, respiration and digestive evacuation in penguins

A system is presented which uses a Hall sensor and an adjacent magnet, attached close to the cloaca of penguins, to record defecation, respiration and heart rates for both free-living birds and those in captivity. The output of the Hall sensor depends on a magnetic field, the strength of which is influenced in the presented scenario by the proximity of the magnet, which varies with movement of the cloaca. The elasticity of the cloaca results in minute, but perceptible, movements associated with the heart, respiration and defecation, although placement of the magnet and sensor is critical, and not all parameters can be measured all of the time. The system, incorporating a logger that can record at frequencies of 50 Hz, was tested on 17 captive and 4 free-living Magellanic penguins, Spheniscus magellanicus, in Argentina. It showed increased defecation rate associated with feeding, the expected trends in bradycardia and tachycardia associated with diving, and appeared to record some movement of air sacs associated with breathing. The concept of measuring minute changes in relative exterior body positions as a cue to internal processes may be important in future studies for both free-living and captive animals, particularly since it is non-invasive and relatively easy to deploy.

A portable surface plasmon resonance (SPR) sensor system with temperature regulation

We describe here the construction of an inexpensive portable, temperature-regulated surface plasmon resonance (SPR) instrument utilizing readily available components. This system is ideal for both laboratory and field use. Applications of SPR-based biosensors range from laboratory assays to continuous or spot monitoring for analytes important in food industries to monitoring for environmental pollutants and agents of bioterrorism. SPR sensors are capable of measuring minute changes in refractive index (RI) to high precision. Changes in temperature affect the materials of the SPR sensor and RI of aqueous sample solutions. Management of the effects of temperature changes on the SPR signal can be achieved by temperature stabilization, compensation, or a combination of both. The multi-channel design described here allows for a reference channel to compensate for bulk RI changes, non-specific binding, and minor temperature variations, while the temperature controller provides the temperature stability necessary for monitoring small changes in RI. The temperature controller also allows for studies of the temperature dependence of molecular interactions and for optimizing detection conditions.

The behavior of quartz crystal microbalance in high pressure CO 2

Quartz crystal microbalance (QCM) is a very useful in situ tool for measuring minute changes of mass of thin surface films with real-time monitoring. The effect of temperature deviation and pressure change, viscosity and roughness loading on the frequency shift were examined by measuring the frequency change of bare QCM under high-pressure CO 2. From a contour analysis, the frequency shift from viscosity loading and that from roughness loading were obtained. Frequency shift from viscosity loading was about three to four times larger than that estimated by Kanazawa's equation. The resonator, whose surface roughness was larger than the diffusion length, exhibited a frequency shift from roughness loading.

Performance of integrated optical microcavities for refractive index and fluorescence sensing

The performance of a novel sensor based on an integrated optical (IO) disk microcavity (MC) is theoretically studied. The MC is a resonant waveguide structure in which multiple interference of a guided mode occurs. At resonance, the MC is extremely sensitive to refractive index changes and it sustains locally enhanced optical field. Therefore, the MC is naturally suitable as an extremely responsive sensor for measuring minute changes in refractive index and/or fluorescence of an analyte. Combination of multiple interference and extremely small sampling volume (few femtoliters) provides unique sensitivity of the MC device. A factor of 9 increase in fluorescence sensitivity versus waveguide sensor is anticipated. Provided shot-noise limited detection, the refractive index resolution down to 10 −9 is feasible with the MC sensor, which exceeds that of the straight waveguide interferometer by the order of magnitude. MC-sensors can be combined into arrays providing high throughput detection of both labeled and non-fluorescent biological species.

Diffraction measurements from crystals under electric fields: instrumentation

Based on the ideas of previous work, a device has been built for applying strong electric fields to a crystal during the measurement of diffracted intensities using a field-switching technique. It consists of a high-voltage supply, the electronics for switching the field, and synchronous counting on four chains combined with controls for step-scanning the diffraction profiles. By using this `stroboscopic' technique, it is possible to measure very small changes in Bragg angles arising from the strain induced by the converse piezoelectric effect, and also to measure minute changes in the Bragg intensities arising from polarizations of atomic structure and electron density.

Neurodiagnostic techniques.

Neurodiagnostic techniques.

Differential effects of in vitro mycoplasma infection on interleukin-1 alpha and beta mRNA expression in U937 and A431 cells.

Cultured cells depend on cytokine mediators for sustained growth and maintenance and are routinely employed in bioassays to detect and measure minute changes in biological mediators, e.g. the interferons and interleukins. We evaluated the effects of mycoplasma infection on the steady-state mRNA levels of two cytokines IL-1 alpha and beta. Noninfected human squamous carcinoma cell line A431 expressed constitutively IL-1 alpha and beta mRNA. In contrast freshly isolated peripheral blood mononuclear cells and the monocytic cell line U937 expressed abundant IL-1 mRNA only after the appropriate stimulation. Peripheral blood mononuclear cells and U937 steady-state IL-1 beta mRNA levels were considerably greater than IL-1 alpha mRNA levels, whereas nearly equivalent high levels of IL-1 alpha and beta mRNA were detected in A431 cells. Mycoplasma infection of cultured A431 cells reduced the steady-state levels of IL-1 alpha and beta mRNA. This effect was nonspecific for A431 cells as actin mRNA steady-state levels showed similar decreases to mycoplasma contamination. However, this response was cell specific since mycoplasma-free and contaminated U937 cells differed little in IL-1 mRNA expression. These results show that the response to mycoplasma infection is at least partly cell-type dependent.

The role of analytical chemistry in academic and industrial chemistry

It is a largely undisputed fact that analytical chemistry - or at least analysis - is of the most fundamental importance not only to all branches of chemistry but also to all the biological sciences, to engineering, and, more recently, medicine, public health, the environment and the supply of energy in all forms. Scientists and technologists need not only to establish the identity of materials but also to quantify their composition and purity and to measure contamination at even tens of nanograms per gram. Even the most abstruse academic researcher needs to be able to analyse his starting materials or products and frequently to measure minute changes in chemical composition in order to be able to draw his conclusions. It is also a largely undisputed and rather curious fact that the United Kingdom, which pioneered the industrial revolution, has largely neglected the academic discipline of analytical chemistry and, even in industry, its position has been downgraded relative to the other main branches of chemistry. During the nineteenth century, academic analytical chemistry was not as widely established in Britain as elsewhere in the world. Furthermore, it suffered such a series of setbacks that by the beginning of the twentieth century it scarcely ranked as an academic discipline of chemistry. Some of the reasons for this astonishing state of affairs are reviewed and the present situation is assessed following the revival that occurred in the middle decades in a few of the universities of the U.K.

Temperature control of a plethysmograph used to measure minute changes in tissue volume

A solid state heater control which matches the heat dissipation rate from a heater element with the thermal conductivity of the bathing fluid-tissue interface was used to minimize artifacts during measurement of minute volume changes (<0.1 ml) in a plethysmograph. Control was achieved by regulating the duration of voltage applied to the heater element.

X-ray-induced mutability of polygenes controlling hatching time in Drosophila melanogaster

Hatching time is a suitable parameter for the study of polygenic mutations in the heterozygous state. Because eggs are relatively closed systems until the moment they hatch, many environmental complications are avoided. Moreover, by means of paired observations it is possible to measure minute changes in hatching time and thus to discern mutations with very small metrical effects. Eggs of non-irradiated females inseminated by irradiated males were studied. Analysis of the results by Bateman's method indicated that the minimum incidence of mutations in sperm was about 26% at 1200 R and 49% at 2400 R. The mean metrical effect of each mutation was to retard hatching time by about 24 min. By this method it is not possible completely to exclude the possibility of some non-genetic physiological component of the changes observed. However it seems rather unlikely that such a component will be significant to any great extent.