Readout Value Research Articles

Evaluation of Hepatitis C Virus Core Antigen Assay in a Resource-Limited Setting in Pakistan.

The diagnosis of Hepatitis C virus (HCV) infection can be challenging due to its cost and a lack of access to centralized testing. There is an urgent need to develop simplified HCV testing algorithms. The aim of this study was to evaluate the performance characteristics of a Hepatitis C core antigen (HCVcAg) assay in a decentralized, resource-limited setting. This is a descriptive cross-sectional study from a highly endemic area of Karachi, Pakistan. Between October 2019 and July 2020, subjects aged 12 years and above who screened positive for HCV antibodies were simultaneously tested for HCV RNA (Xpert HCV Viral Load, GeneXpert® IV, Cepheid, France) and HCVcAg (ARCHITECT HCV Ag assay, Abbott® Diagnostics) to confirm active HCV infection. An Abbott ARCHITECT® i1000SR Immunoassay Analyser was installed at a local district hospital as a point-of-care (POC) facility for HCVcAg testing, while samples for HCV RNA were tested in a central lab. Two hundred individuals (mean age 46.4 ± 14.5 years, 71.5% females), who screened positive for HCV antibody, were included in the study. HCV RNA was detected in 128 (64.0%) while HCVcAg was reactive in 119 (59.5%) cases. Performance of the Immunoassay Analyser was excellent with a higher throughput and quicker readout value compared to the GeneXpert System. The sensitivity and specificity of HCVcAg (≥10 fmol/L) at HCV RNA thresholds of ≥12 was 99.1% (95% CI: 95–100%) and 87.6% (95%CI: 78.4–94%). A strong agreement was observed between the HCVcAg assay and HCV RNA. The ARCHITECT HCV Ag assay showed high sensitivity and specificity compared to HCV RNA in a decentralized, resource-limited setting. It can therefore be used as a confirmatory test in HCV elimination programs, particularly for low-income countries such as Pakistan.

Transcription Factor Binding Affinities and DNA Shape Readout.

SummaryAn essential event in gene regulation is the binding of a transcription factor (TF) to its target DNA. Models considering the interactions between the TF and the DNA geometry proved to be successful approaches to describe this binding event, while conserving data interpretability. However, a direct characterization of the DNA shape contribution to binding is still missing due to the lack of accurate and large-scale binding affinity data. Here, we use a binding assay we recently established to measure with high sensitivity the binding specificities of 13 Drosophila TFs, including dinucleotide dependencies to capture non-independent amino acid-base interactions. Correlating the binding affinities with all DNA shape features, we find that shape readout is widely used by these factors. A shape readout/TF-DNA complex structure analysis validates our approach while providing biological insights such as positively charged or highly polar amino acids often contact nucleotides that exhibit strong shape readout.

Enhancing the Matrix Addressing of Flexible Sensory Arrays by a Highly Nonlinear Threshold Switch.

The increasing need for smart systems in healthcare, wearable, and soft robotics is creating demand for low-power sensory circuits that can detect pressure, temperature, strain, and other local variables. Among the most critical requirements, the matrix circuitry to address the individual sensor device must be sensitive, immune to disturbances, and flexible within a high-density sensory array. Here, a strategy is reported to enhance the matrix addressing of a fully integrated flexible sensory array with an improvement of 108 fold in the maximum readout value of impedance by a bidirectional threshold switch. The threshold switch shows high flexibility (bendable to a radius of about 1 mm) and a high nonlinearity of ≈1010 by using a nanocontact structure strategy, which is revealed and validated by molecular dynamics simulations and experiments at variable mechanical stress. Such a flexible electronic switch enables a new generation of large-scale flexible and stretchable electronic and optoelectronic systems.

Frequency of a large drift caused by pressure wire using optical fibers.

The frequency of a large pressure signal drift (PDs) caused by pressure wire using optical fibers and its effect on fractional flow reserve (FFR)-based decision-making is not clear. We used pressure wires using optical fibers as "workhorse wires" for 95 consecutive lesions. The wire was normalized at the tip of the guiding catheter just before performing the percutaneous coronary intervention (PCI) and was used without re-normalization until the end of the PCI. The drift value at the end of the procedures was evaluated. Four per cent (n=4) of patients showed a large drift (PD >3mmHg). Classification discordance between read-out and PD-corrected FFR values was detected in 8 (8%) measurements in total. The decision changed from FFR ≤0.80 to >0.80 in 7 (7%) measurements and vice versa in 1 (1%) measurement. PD showed no effect on decision-making when the FFR read-out value was <0.78 or >0.82. The frequency of large drifts caused by pressure wires using optical fibers was 4%. However, no case showed decision changes when the FFR gray zone was considered.

A novel Blood Pressure estimation method combing Pulse Wave Transit Time model and neural network model.

Blood Pressure (BP) measurement can assist doctors to assess patients' cardiovascular status and diagnose heart diseases. Pulse Wave Transit Time (PWTT) model is one frequently used BP estimation method to monitor BP continuously in clinics. However, individual variations may influence the measurement accuracy of PWTT model. Focusing on above promble, this paper proposes a novel BP estimation method combining a classical PWTT model and a neural network model. The novel method is composed of five steps: signal pre-processing, feature extraction, initial PWTT model selection, model correction by neural network model, and final PWTT model identification. A validation experiment based on 10 patients from Multiparameter Intelligent Monitoring in Intensive Care (MIMIC) database showed that the BP estimation results by our method had a minimum mean of error readout value 5 mmHg with a standard deviation of error readout value ±8mmHg. As a result, both the diastolic blood pressure and systolic blood pressure estimation by our method can meet clinical requirements.

Reference line correcting method and accuracy analysis of fingernail electron paramagnetic resonance

Objective The spectrum has a greater baseline drift when wind speed, temperature and humidity change in the experiment of fingernail electron paramagnetic resonance dose reconstruction, and thus the read-out value does not reflect the true radical concentration, which ultimately reduces the credibility of the test results. This study aims to propose a reference line correcting method to solve the problem. Methods The drifted baseline was found out first, and then spectral correction range and the corresponding correction function were selected or the original spectrum was reduced to energy absorption spectrum. Finally, the point correction method was applied to modify the spectrum. Results The probability of the value obtained without reference line correcting for the spectrum of baseline drift equal to the value of spectrum without baseline drift was only 31%, while the probability was increased to 91%, improving nearly 3 times after using the reference line correcting method in the range of acceptable error. Conclusions This reference line correcting method for spectrum should be applied before reading the spectrum in order to increase the accuracy of dose estimation. Key words: Electron paramagnetic resonance; Spectrum; Reference line correcting; Fingernail; Baseline drift

Label-free detection of sex determining region Y (SRY) via capacitive biosensor.

In this work, we present for the first time, the use of a simple fractal capacitive biosensor for the quantification and detection of sex-determining region Y (SRY) genes. This section of genetic code, which is found on the Y chromosome, finds importance for study as it causes fetuses to develop characteristics of male sex-like gonads when a mutation occurs. It is also an important genetic code in men, and disorders involving the SRY gene can cause infertility and sexual malfunction that lead to a variety of gene mutational disorders. We have therefore designed silicon-based, label-free fractal capacitive biosensors to quantify various proteins and genes. We take advantage of a good dielectric material, Parylene C for enhancing the performance of the sensors. We have integrated these sensors with a simple microchannel for easy handling of fluids on the detection area. The read-out value of an Agilent LCR meter used to measure capacitance of the sensor at a frequency of 1 MHz determined gene specificity and gene quantification. These data revealed that the capacitance measurement of the capacitive biosensor for the SRY gene depended on both the target and the concentration of DNA. The experimental outcomes in the present study can be used to detect DNA and its variations in crucial fields that have a great impact on our daily lives, such as clinical and veterinary diagnostics, industrial and environmental testing and forensic sciences.

Impact of Pressure Signal Drift on Fractional Flow Reserve-Based Decision-Making for Patients With Intermediate Coronary Artery Stenosis.

Fractional flow reserve (FFR) is an important physiological measure of intermediate coronary artery stenosis. Pressure signal drift (PD) is widely recognized but has largely been ignored in FFR measurements. We sought to determine the effect of PD on FFR-derived decision-making. We analyzed 1,218 FFR measurements for intermediate stenosis in 940 patients, in which the pullback maneuver confirmed PD ≤3 mmHg. The primary objectives were to determine the frequency and magnitude of PD and its effect on decision-making on the basis of an FFR cutoff of 0.80. In all, 479 (39.3%) measurements showed PD. PD was significantly associated with age, hypertension, reference diameter, left anterior descending artery lesion location, and read-out FFR values. Classification discordance between read-out and PD-corrected FFR values was detected in 44 (3.6%) measurements in total and in 9.2% of PD cases. The decision changed from FFR ≤0.80 to FFR >0.80 in 40 (3.3%) and vice versa in 4 (0.3%) measurements. PD showed no effect on decision-making when the FFR read-out value was ≤0.76 or ≥0.83. PD is not uncommon, and its effect on FFR-based decision-making was not negligible in the range between 0.77 and 0.82 where reclassification occurred in 18.7% of FFR measurements. (Circ J 2016; 80: 1812-1819).

Синтез нелінійного приймача сигналів АЛСН в умовах дії адитивної двокомпонентної завади

The introduction of high speed traffic on railway transport stipulates for the necessity to solve the task of the improvement of the existing systems of automatic locomotive signaling which are considerably subjected to the influence of electromagnetic interferences of different natureAs a rule these interferences are multicomponent and their components are statistically independent. The aim of the given work is the synthesis of the algorithm and hardware-based structure of the receiver, working in the conditions of additive two-component interference.It has been shown that the given receiver must form some two magnitudes called weighted correlated and weighted energy sums.The summation is done with weighting coefficients, nonlinearly depending on readout value of signal voltage coming to processing. The structure of the corresponding receiver is four-channel with two inertialess nonlinear converters at common input.The synthesized device ensures optimal reception of signals on the background of two-component interferences with a wide class of probability density functions of instantaneous values of their voltages.

The analysis of readout values according to reading methods: Glass dosimeter reader

The accuracy and precision of dose measurement using a glass dosimeter (GD) depend on appropriate and stable operation of the GD reader. The aim of this study is to evaluate the stability of readout values of the reader and to recommend effective use of reading methods for reducing the uncertainty in dosimetric performance through the investigation of characteristics of a GD-based reader system. The examined glass dosimetry system consists of silver-activated metaphosphate GD element and a fully automatic readout system. GD elements were calibrated and exposed using a 60Co teletherapy unit (Theratron 780, AECL, Kanata, Canada). The reproducibility of repeated measurements results show that the readout value is 0.4% lower at fifth measurement, 0.9% lower at tenth measurement, and 1.3% lower at the twentieth measurement, compared to the reference value. The resulting readout values of the GD elements according to the loading positions were at minimum 0.5% lower, and at maximum, 3.1% higher, with an average of 2.0% higher values compared to the reference readout value in the first position. The interface effect for dose due to the loading number of GD elements was evaluated to be 1.015, 1.022, and 1.035 times higher in the average dose values for the loading of five GD elements, ten GD elements, and twenty GD elements than the average readout value at the first position, respectively. As a result, in order to get an accurate and precise dose measurement by the GD reader, if repeated readings are performed, measured values should be corrected according to the number of repeated readings, and the loading of GD elements in the magazine should constantly be kept in the same position. Moreover, the number of GD elements loading on the magazine should be decided by considering either accurate and precise dose measurements or numerous relative dose measurements.

Infectivity of hepatitis C virus correlates with the amount of envelope protein E2: Development of a new aptamer-based assay system suitable for measuring the infectious titer of HCV

Various forms of hepatitis C virus (HCV)-related particles are produced from HCV-infected cells. Measuring infectivity of a HCV sample with the conventional ‘foci counting method’ is laborious and time-consuming. Moreover, the infectivity of a HCV sample does not correlate with the amount of viral RNA that can be measured by real-time RT-PCR. Here we report a new assay suitable for quantifying infectious HCV particles using aptamers against HCV E2, which is named ‘Enzyme Linked Apto-Sorbent Assay (ELASA)’. The readout value of HCV ELASA linearly correlates with the infectious dose of an HCV sample, but not with the amount of HCV RNA. We also demonstrated that the activities of anti-HCV drugs can be monitored by HCV ELASA. Therefore, HCV ELASA is a quick-and-easy method to quantify infectious units of HCV stocks and to monitor efficacies of potential anti-HCV drugs.

Effective radiation attenuation calibration for breast density: compression thickness influences and correction

BackgroundCalibrating mammograms to produce a standardized breast density measurement for breast cancer risk analysis requires an accurate spatial measure of the compressed breast thickness. Thickness inaccuracies due to the nominal system readout value and compression paddle orientation induce unacceptable errors in the calibration.MethodA thickness correction was developed and evaluated using a fully specified two-component surrogate breast model. A previously developed calibration approach based on effective radiation attenuation coefficient measurements was used in the analysis. Water and oil were used to construct phantoms to replicate the deformable properties of the breast. Phantoms consisting of measured proportions of water and oil were used to estimate calibration errors without correction, evaluate the thickness correction, and investigate the reproducibility of the various calibration representations under compression thickness variations.ResultsThe average thickness uncertainty due to compression paddle warp was characterized to within 0.5 mm. The relative calibration error was reduced to 7% from 48-68% with the correction. The normalized effective radiation attenuation coefficient (planar) representation was reproducible under intra-sample compression thickness variations compared with calibrated volume measures.ConclusionIncorporating this thickness correction into the rigid breast tissue equivalent calibration method should improve the calibration accuracy of mammograms for risk assessments using the reproducible planar calibration measure.

Study of a new Lif:Mg,Cu,P formulation with enhanced thermal stability and a lower residual TL signal

This paper presents results obtained for a new LiF:Mg,Cu,P (HMCP) preparation with modified Mg and Cu concentrations. The shape of the HMCP glow curve shows minimal differences for annealing in the range from 523 to 543 K for 10 min. The thermoluminescence (TL) readout value remained stable when annealed in the range from 513 to 543 K for 10 min. The new formula allows heating of the material to higher temperatures than that originally employed for the well-known GR-200A dosemeter, practically without losses in sensitivity. The TL sensitivity is approximately half of that for the GR-200A, and still 29-fold greater than that for the TLD-100 dosemeter, and the residual signal is approximately five-fold lower than for the GR-200A. These results indicate that the new TL material shows enhanced thermal stability and a lower residual TL signal at a small TL sensitivity cost. The heat treatment temperatures are related to concentrations of Mg and Cu in LiF:Mg,Cu,P.

Luminescence lifetime-based carbon dioxide optical sensor for clinical applications

The development of both an optical planar and capillary based carbon dioxide sensor, which final aim is pCO 2 monitoring in adipose tissue of critically ill patients, is reported. The sensor is based on the measuring principle of phase fluorometry using a dual luminophore referencing scheme (DLR) to convert the CO 2 dependent intensity signal into phase domain. The CO 2 sensors have been prepared by incorporating two appropriate luminophores and a phase transfer agent in a same hydrophobic polymer as matrix. The short-lifetime luminophore used as pH indicator is 8-hydroxypyrene-1,3,6-trisulfonic acid trisodium salt (HPTS). The second inert luminophore is the long-lifetime dye Ruthenium(II) tris(4,7-diphenyl-1,10-phenanthroline) (Ru(dpp) 3 2+), which has been made insensitive to oxygen by immobilising in a suitable oxygen impermeable polymer. As phase transfer agent, tetraoctylammonium hydroxide (TOA-OH) has been chosen. Both sensor types have been characterised with respect to optimise sensitivity and mechanical stability. For this purpose, several polymers, such as ethylcellulose, eudragit RL100 (EG), copolymer eudragit/poly(ethylene glycol) (PEG) and silicone have been examined as appropriate matrix for incorporation of two indicators. The largest phase shift up to 13° and 15° has been observed in the case of silicone and copolymer EG/PEG, respectively, and they have been in detail examined in terms of sensitivity and stability. The presented sensors enable the measurement of pCO 2 in the range from 0 to 150 mmHg, with a resolution of 0.5 mmHg and an accuracy of ±1 mmHg absolute or less than 7% of the read-out value. All measurements have been carried out only in aqueous solutions before clinical measurements.

Comparison on characteristics of radiophotoluminescent glass dosemeters and thermoluminescent dosemeters

The radiophotoluminescent glass dosemeter (RPLGD) system is applicable for measurement of radiation dose of X rays and gamma rays by using radiophotoluminescent glass (silver-activated phosphate glass). When the radiophotoluminescent glass is exposed to ionizing radiation, stable luminescent centres are created. During pulsed ultraviolet laser excitation (337.1 nm) in the reader, the centres emit a radiation induced orange fluorescent light (600-700 nm). This phenomenon is called radiophotoluminescence. This study compared the RPLGD system with lithium fluoride (LiF) thermoluminescence dosimetry system and the results of the study revealed that the RPLGD had not only good basic characteristics for reproducibility of readout value, dose linearity, energy dependence and fading, but also infinite repeatable measurements and could be one of the most important radiation dose measurement instruments.

Musical tone synthesizing apparatus using wave guide synthesis

First Page

Potential errors in pulse oximetry

There is no absolute reference for oxygen saturation, although multiwavelength in vitro oximeters are accepted as the 'gold standard'. Regardless of whether fractional or functional saturation is used by manufacturers to calibrate their oximeters, evaluation against fractional saturation is recommended since this is the clinically relevant variable. The use of standard notation and comparisons based on bias and precision is recommended. The accuracy of pulse oximetry is intrinsically limited by the use of only two wavelengths, and is dependent on the initial calibration population. The empirical algorithms used to convert the signal to its 'readout value' and the quality control of hardware may both be important sources of variability between oximeters. Change in blood temperature may introduce errors in pulse oximeter and in vitro oximeter saturation readings, but these will be clinically insignificant. Changes in blood pH should not decrease pulse oximetry accuracy.

Mental Workload and P300 Component of Event-Related Brain Potentials in a Visual Monitoring Task

The attributes of event-related brain potentials (ERPs) when combined with the information gained from the study of apparent human behavior, can provide valuable information about central nervous system processes. This study illustrates the manner in which these attributes, specifically P300 amplitude, can be used to study human information processing. This research investigated the effects of a systematic increase in mental workload, and the position of the stimulus on the P300 amplitude. The task chosen was a visual monitoring task with four levels of increased task difficulty. A slight increase in the P300 amplitude was observed from level 1 to level 2. At level 3, a significant increase in the amplitude of P300 component was observed from level 2. At level four, no major increase in the P300 amplitude was observed from level 3. At any task difficulty level, the P300 amplitudes were not affected by the position of the monitored cell. Infrequent large changes in the readout value of the monitored cells elicited larger P300 amplitudes than frequent small changes.

補助磁極にＮｉ‐Ｆｅ膜を用いたＮｉ‐Ｃｏ膜磁気抵抗効果素子

Magnetoresistive effect, effective anisotropy field, domain patterns and reading abilities were studied in improved type sensors made of high magnetoresistive Ni-Co films with auxiliary pole of Ni-Fe films. Demagnetizing field in improved type sensors with the same Ni-Co stripe width as conventional type sensors was reduced to half that of the latter. Under an angular change of applied field or an application of low bias field, magnetoresistive effect in conventional type sensors decreased. This was caused by the existence of domain walls. On the other hand, improved type sensors were composed of a single domain; therefore, magnetoresistive effect did not decrease under the same field conditions. Read-out value for magnetoresistive effect of improved type sensors is about 1.6-1.8 times greater than that of conventional type sensors. The ratio of the stripe width of the sensors to the recording bit length was found to be an important factor in enlarging the distance from a medium to the sensors.

An aerodynamic particle size analyser tested with spheres, compact particles and fibres having a common settling rate under gravity

A Timbrell Aerosol Spectrometer was modified to allow the withdrawal of particles of known settling velocity which were then passed into an inertial aerodynamic particle size analyser, so that the latter's read-out of aerodynamic diameters could be checked. Excellent agreement between the read-out value with that calculated from settling velocity was found for spherical particles of unit density. Silicon carbide particles of the same settling velocity, but of a nonspherical shape and of higher density, were also withdrawn and passed into the aerodynamic particle size analyser. The displayed value of aerodynamic diameter was the same as that of the unit-density spheres of the same settling velocity, for aerodynamic diameters of less than (approximately) 5 μm. Above this size the APS appeared to undersize the SiC particles. In addition to this, glass fibres of the same settling velocity were withdrawn and passed into the aerodynamic particle sizer. For fibres, the displayed values of aerodynamic diameters were less than that of the unit-density spheres of the same settling velocity for sizes smaller than 5 μm and then increased. The values of aerodynamic diameter for these fibres, calculated from the settling velocities were, however, found to agree with theory. The range of aerodynamic diameters covered was 1–8 μm.