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The dynamical system containing flag-shaped hysteretic behavior is common in practice. In this paper, the stationary response of flag-shaped hysteretic system excited by harmonic excitation as well as Gaussian white noise is determined with the technique of stochastic averaging. The reliability of the presented approach is demonstrated by relevant digital simulation. The stochastic jump under a certain combination of parameters is found. The stochastic P-bifurcation phenomenon, i.e., the disappearance or appearance of bimodal shape of stationary response, occurs concerning to the variation of system’s parameters. Besides, the response of the system exposed to only harmonic excitation or non-resonance case is also examined for comparison, respectively. The numerical results show that the stationary amplitude response displays typical “soft” system behavior, and the deterministic jump may occur under pure harmonic excitation. Moreover, the non-resonance response is always weaker than that of resonant case.

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BACKGROUND AND PURPOSE: Posterior fossa tumors are the most common pediatric brain tumors. MR imaging is key to tumor detection, diagnosis, and therapy guidance. We sought to develop an MR imaging–based deep learning model for posterior fossa tumor detection and tumor pathology classification. MATERIALS AND METHODS: The study cohort comprised 617 children (median age, 92 months; 56% males) from 5 pediatric institutions with posterior fossa tumors: diffuse midline glioma of the pons (n = 122), medulloblastoma (n = 272), pilocytic astrocytoma (n = 135), and ependymoma (n = 88). There were 199 controls. Tumor histology served as ground truth except for diffuse midline glioma of the pons, which was primarily diagnosed by MR imaging. A modified ResNeXt-50-32x4d architecture served as the backbone for a multitask classifier model, using T2-weighted MRIs as input to detect the presence of tumor and predict tumor class. Deep learning model performance was compared against that of 4 radiologists. RESULTS: Model tumor detection accuracy exceeded an AUROC of 0.99 and was similar to that of 4 radiologists. Model tumor classification accuracy was 92% with an F1 score of 0.80. The model was most accurate at predicting diffuse midline glioma of the pons, followed by pilocytic astrocytoma and medulloblastoma. Ependymoma prediction was the least accurate. Tumor type classification accuracy and F1 score were higher than those of 2 of the 4 radiologists. CONCLUSIONS: We present a multi-institutional deep learning model for pediatric posterior fossa tumor detection and classification with the potential to augment and improve the accuracy of radiologic diagnosis.

Capillary electrophoresis (CE) procedure was developed for determining glucosamine content in nutraceuticals. Glucosamine was labeled with o-phthalaldehyde (OPA) by mixing with the OPA reagent (4.5 mM OPA, 4.5 mM 2-mercaptoethanol dissolved in 20 mM borate buffer, pH 9.3). The fluorescent OPA-glucosamine adduct was separated and detected at A340 within 3 min. The pre-capillary labeling reaction can be performed by sequentially injecting OPA/sample/OPA segments into the separation capillary; the in-capillary labeling technique simplified the sample pretreatment and improved its reproducibility. The linear dynamic range of the in-capillary labeling CE method was 0.1~30 mM. No sample pretreatment procedure was required for tablets containing mainly starch or other sugar as the vehicles.

Visible/near-infrared transmittance spectra (600-1368 nm) of the aqueous extracts of 120 ground pork tenderloin samples from Taiwan black-hair hogs were used to correlate with the freshness-relating data including pH, volatile basic nitrogen and aerobic plate count during 7℃ storage for 5 days. The spectra in 600-840 nm regions varied during storage with the data highly correlated with the freshness parameters. Four characteristic wavelengths (608, 624, 656 and 732 nm) were selected for freshness evaluation based on partial least square regression (PLSR) model using different freshness criteria for dummy regression. The accuracies of freshness evaluation can reach 90% with the PLSR models excluding the data in Day 3.

This study develops a hand-held stress assessment meter with a chemically colorimetric strip for determining salivary &alpha, amylase activity, using a 3,5 dinitrosalicylic acid (DNS) assay to quantify the reducing sugar released from soluble starch via &alpha, amylase hydrolysis. The colorimetric reaction is produced by heating the strip with a mini polyester heater plate at boiling temperature to form a brick red colored product, which measured at 525 nm wavelength. This investigation describes in detail the design, construction, and performance evaluation of a hand-held &alpha, amylase activity colorimeter with a light emitted diode (LED) and photo-detector with built-in filters. The dimensions and mass of the proposed prototype are only 120 &times, 60 &times, 60 mm3 and 200 g, respectively. This prototype has an excellent correlation coefficient (&gt, 0.995), comparable with a commercial ultraviolet&ndash, visible spectroscope, and has a measurable &alpha, amylase activity range of 0.1&ndash, 1.0 U mL&minus, 1. The hand-held device can measure the salivary &alpha, amylase activity with only 5 &mu, L of saliva within 12 min of testing. This sensor platform effectively demonstrates that the level of salivary &alpha, amylase activity increases more significantly than serum cortisol, the other physiological stressor biomarker, under physiologically stressful exercise conditions. Thus, this work demonstrates that the hand-held &alpha, amylase activity meter is an easy to use and cost-effective stress assessment tool for psychoneuroendocrinology research.

An online dynamic pH junction preconcentration method was developed for quantification of 5-aminolevulinic acid (ALA) by CE with the separation time less than 6 min. The optimal dynamic pH junction of ALA was carried out between pH 9.3 borate buffer (BGE, 40 mM) and pH 2.5 phosphate buffer (sample matrix, 40 mM) when 4.1 cm of sample plug was hydrodynamically injected into an uncoated fused-silica capillary (48.5 cm in length, id of 50 μm). If a 24 kV separation voltage was applied, the calibration curve of ALA peak area (200 nm) showed good linearity (R(2) = 0.9991) ranging from 0.01 to 6.5 mg/mL. The reproducibility of this system was excellent with RSDs (n = 10) of 2.5% for peak area response and 0.6% for migration time at ALA concentration of 0.5 mg/mL. The LOD was evaluated as 1.0 μg/mL (S/N > 3). Compared to conventional CE procedure, the sensitivity was successfully improved over 50-fold. The analytical results of pharmaceutical formulations show a good agreement with those by HPLC (r = 0.94).

The biodiesel content or blending ratio of a biodiesel fuel is crucial for the quality control and official regulation. A rapid ( −1 ) detection chamber composed of a hydrophobic electrode pair (two identical screen-printed carbon paste electrodes) to improve the data precision. In low frequency region ( n = 8) was useful to estimate the blending ratio of biodiesel ( r 2 > 0.98) with good resolution, reproducibility and thermal stability, which is important for the quality control and regulation of the eco-friendly fuel.

A microelectrode was fabricated by electrochemical etching of a pencil lead (0.5 mm in diameter) in 1.0 M NaOH aqueous solution. The pencil lead was dipped into the solution and then an ac voltage (3.0 V rms for 10 min) was imposed against a stainless plate under mild stirring (450 rpm). The electrochemically sharpened pencil tip was about 10 μm in diameter (12 ± 3 μm, n = 5), and the lateral part was insulated within a polypropylene micro-pipette tip (2–200 μL volume range). The cyclic voltammograms conducted in 2.0 mM ferricyanide/ferrocyanide buffer solution (pH 7.0) are with low capacitive current and a typical sigmoidal signal of micro-sized electrodes. The microelectrode was used to perform dielectrophoresis of polystyrene latex microbeads (nominal diameter of 3 μm) and human red blood cells. A conducting glass (indium tin oxide coated glass, 40 mm × 40 mm × 1 mm) served as the counter electrode (0.5 mm beneath the microelectrode) to generate the asymmetrical electric field and also as the window for microscopic observation. With the sinusoidal bias voltage (30 V rms ) ranged from 20 Hz to 2 MHz, positive and negative dielectrophoretic phenomena were identified.

β(1 → 3)-d-Glucan sensors were fabricated using bi-enzyme and tri-enzyme immobilized systems with gold nanoparticles (GNPs) to increase sensitivity. The plant β(1 → 3)-d-glucanase (βG), glucose oxidase (GOD) or/and peroxidase (POD) in agarose–corn flour–gelatin (ACG) matrix were coated on platinum disc electrode to detect soluble β(1 → 3)-d-glucan. The atomic force microscopy (AFM) revealed that GNPs embedded in ACG formed tiny islands/clusters with enzymes. Both of bi-enzyme sensor (ACG–βG–GOD–GNPs/Pt) and tri-enzyme sensor (ACG–βG–GOD–POD–GNPs/Pt) had response time less than 20 s for β(1 → 3)-d-glucan. A linear calibration plot for bi-enzyme sensor was obtained for β(1 → 3)-d-glucan concentration ranged from 100 to 1000 ng mL−1 (R2 = 0.983). The lower detection limit was 30 ng mL−1 using applied potential of 200 mV and scan rate of 50 mV s−1; with signal to noise ratio (S/N) of 3. Fabricated tri-enzyme sensor was also operable under similar conditions with LOD of 50 ng mL−1 (R2 = 0.989) at −175 mV applied potential and scan rate of 50 mV s−1. Both sensors were durable and could be repeatedly used for at least 14 times. When the tri-enzyme sensor was employed to analyze β(1 → 3)-d-glucan content in alcoholic beverages, the results were comparable to those obtained by standard method.

A micellar electrokinetic capillary electrophoresis (MEKC) method was used to rapidly determine seven tea catechins, three xanthines, gallic acid, vitamin C, theanine and theaflavin in tea. All the compounds were successfully separated (20 kV) within 8 min of migration in the running buffer (pH 7.0) containing 10 mM phosphate, 4 mM sodium tetraborate, 45 mM SDS and 0.5% ethanol. The linear dynamic ranges for polyphenols were from 2.5 (S/N >8) to 100 μg/ml. As revealed by the electropherograms, tea catechins were found to be depleted along with the indoor withering process for making pouching tea, and the fermentation degree can be quantified. The results were compared with the redox potentials of tea infusions.

A flow system, coupled with visible light scattering method, was developed for tannin determination based on the ability of the tannic acid to precipitate bovine serum albumin (BSA). The amount of precipitated tannic acid- BSA is measured directly by scattering intensity of visible light (600 nm), which is properly related to the tannic acid concentration and conformed by a particle sizing method. Scattering signals were non-significant compare with background produced by BSA in both solutions lower than pH4 and higher than pH8. The tannic acid-protein precipitates on pipeline wall and sensing cell could be effectively removed by 22 cm of SDS stream. The system performed a linear detection range 70-100 μg/ml of tannic acid with a detect limit 40 μg/ml in pH5 solution. It also could be used in medium solution with detection ranges were over 420-500 μg/ml and 700-1000 μg/ml in pH6 and pH 7, respectively. The proposed method had good correlations (r2 > 0.97) with the ferrous tartrate method in analysis of both one tannic acid and two tea tannins samples.

A novel fluorometric flow-injection analytical system is utilised to determine tannin and total amino acid levels in tea for taste assessment of astringency and umami, respectively. The quenching effect on fluorescence of 3-aminophthalate was employed to determine tannin levels, and the fluorogenic reaction of o-phthalaldehyde (OPA) was applied to quantify amino acid content. Both reactions were measured by a single fluorescence sensing system with same excitation and emission wavelengths (340/425 nm). A three-way valve was introduced to switch reagents for sequential determination of tannin and amino acids levels. Parameters of operational conditions were optimised, and the effect of tannic acid on OPA-based amino acid determination was also investigated. The linear dynamic ranges for tannic acid and theanine are 50–250 and 0.1–1.0 μg mL−1 (CV

The reliability of quasi-integrable generalized Hamiltonian systems is studied. An m -dimensional integrable generalized Hamiltonian system has M Casimir functions C 1 , … , C M and n ( n = ( m − M ) / 2 ) independent first integrals H M + 1 , … , H M + n in involution. When an integrable generalized Hamiltonian system is subjected to light dampings and weakly stochastic excitations, it becomes a quasi-integrable generalized Hamiltonian system. The averaged Ito equations for slowly processes C 1 , … , C M , H M + 1 , … , H M + n can be obtained by using stochastic averaging method, from which a backward Kolmogorov equation governing the conditional reliability function and a Pontryagin equation governing the conditional mean of the first passage time are established. The conditional reliability function and the conditional mean of first passage time are obtained by solving these equations together with suitable initial condition and boundary conditions. Finally, an example of a 5-dimensional quasi-integrable generalized Hamiltonian system is worked out in detail and the solutions are confirmed by using a Monte Carlo simulation of the original system.

The first passage failure of single-degree-of-freedom (SDOF) strongly nonlinear stochastic system with fractional derivative damping is studied. The stochastic averaging method for SDOF strongly nonlinear stochastic system with fractional derivative damping under white noise excitations using the generalized harmonic function is introduced. The averaged Itô equation for Hamiltonian is obtained by using the stochastic averaging method. Then, a backward Kolmogorov equation governing the conditional reliability function and a Pontryagin equation governing the mean of the first passage time are established. The conditional reliability function, and the conditional probability density and mean first passage time are obtained from solving these equations together with suitable initial condition and boundary conditions. Finally, two examples are worked out in detail and the solutions are confirmed by using Monte Carlo simulation of original systems.

An amperometric flow-injection assay was proposed for measuring the levels of tannin in tea. Electrode fouling owing to electro-oxidation of tannin could be efficiently avoided by utilizing ferricyanide as an oxidant to pre-oxidize tannin for indirect quantification without electrode modification. Appropriate concentrations of ferricyanide were pre-mixed with tannic acid and then measured by a platinum electrode in an electrochemical flow cell. The effects of working potential and flow rate on amperometric response were investigated, and the optimal condition was obtained when the working potential was −0.1 V (versus Ag/AgCl) and the flow rate was 2.28 mL min −1 in this work. The linear detection range for tannic acid could be effectively adjusted according with application demand, and the results of this study indicated two ranges of 10–50 μg mL −1 and 100–500 μg mL −1 (CV n = 3). Beverage samples of tea with various fermentation degrees were measured (15 samples h −1 ) and verified with Folin–Ciocalteau method ( r = 0.9794) as well as the ferrous tartrate method ( r = 0.9918).

Roselle (Hibiscus sabdariffa L.) is known to possess strong antioxidative capacity mainly due to its high content of anthocyanins and ascorbic acid. This study aimed to elucidate the ratio of contribution of these compounds in Roselle extract towards superoxide anion scavenging capabilities through analysis using electron spin resonance (ESR) coupled with the hypoxanthine/xanthine oxidase system and DMPO spin trapping technique. The ESR analysis indicated that the IC50 of Roselle extract against superoxide anion was 0.25 mg/ml. After depleting the ascorbate in Roselle extract (0.25 mg/ml) with ascorbate oxidase, the remaining superoxide anion scavenging capacity was determined to be 30.5%, which revealed that ascorbic acid substantially facilitated the scavenging process. By both HPLC and LC/MS analyses, the major active anthocyanins in Roselle crude pigments were identified as delphinidin-3-sambubioside (71.2% of total peak area), delphinidin-3-glucoside (8.7% of total peak area) and cyanidin-3-sambubioside (16.1% of total peak area). Approximately 80% of the superoxide anion scavenging capacities of these anthocyanins was from delphinidin-derivatives (delphinidin-3-sambubioside and delphinidin-3-glucoside); the other 20% was from cyanidin-derivative (cyanidin-3-sambubioside).

Chitinous materials are important sources for many bio-medical applications; and the process monitoring is a key factor for better quality control of chitosan production. In this study, chitin and chitosan in suspension form were analyzed using near infrared (NIR) spectroscopy. Two models including multiple linear regression (MLR) and modified partial least square regression (MPLSR) were adopted for studying the degree of deacetylation (DD) of chitinous materials in order to assure a better quality monitoring and control for chitosan production. During the process of the deacetylation, the real-time measurements of suspension were conducted. The MPLSR model with second derivative spectra in the range of 600–1000 and 1400–1500 nm yielded the best results, which were rc = 0.991, SEC = 0.019, RESC = 1.4%, rp = 0.990, SEP = 0.022, RSEP = 3.4%, RPD = 9.4. The NIR measurements of DD status of chitinous suspension could be achieved by using either MLR or MPLSR model developed in this study. It provides great application potentials to the real-time and on-line inspection for the quality monitoring and control of the chitosan production during deacetylation process.

An amperometric flow-injection choline biosensor was assembled utilizing natural chitinous membrane as the supporting material for biocatalyst immobilization, and the membrane was purified from Taiwanese soldier crab, Mictyris brevidactylus. The chitinous membrane (50.0 microm in thickness) was covalently immobilized with choline oxidase (EC 3.1.1.17 from Alcaligenes sp.) and then attached onto the platinum electrode of an amperometric flow cell. The flow cell served as the choline sensing device of the proposed FIA system. The sensor signal (peak height of the FIAgram) was linearly related to choline concentration (r=0.999 for choline up to 5.0mM) with low detection limit (S/N3 for 10.0 microM choline) and high reproducibility (CV3% for 1.0mM choline, n=7). The system was proved to be useful in measuring cholinesterase inhibitory activities of synthetic chemicals or natural products.

A rapid capillary electrophoresis procedure was developed for determining the anti-cancer components, camptothecins, in Nothapodytes foetida. The hydrophobic compound was extracted from plant tissue (ca. 1 mL of DMSO for 100 mg of dried plant tissue) with a water-miscible organic solvent, DMSO, at elevated temperature (60°C). The extract was directly injected into the separation capillary (untreated fused silica, 34 cm in length, 75 µm i.d.) and analysed in MEKC mode (369 nm). Within 5 min of migration, camptothecins were successfully separated and quantified by adding organic modifiers to the running buffer (20% DMSO, 90 mm SDS in 10 mm borate buffer, pH 8.60). The linear dynamic range for camptothecin was from 5 to 400 µg/mL. This method was proven to be very suitable for monitoring the amount of camptothecins during the cultivation of the medicinal plant. Copyright © 2007 John Wiley & Sons, Ltd.

Errors in measurement frequently occur in observing responses. If case–control data are based on certain reported responses, which may not be the true responses, then we have contaminated case–control data. In this paper, we first show that the ordinary logistic regression analysis based on contaminated case–control data can lead to very serious biased conclusions. This can be concluded from the results of a theoretical argument, one example, and two simulation studies. We next derive the semiparametric maximum likelihood estimate (MLE) of the risk parameter of a logistic regression model when there is a validation subsample. The asymptotic normality of the semiparametric MLE will be shown along with consistent estimate of asymptotic variance. Our example and two simulation studies show these estimates to have reasonable performance under finite sample situations.

Mycobacteriosis due to infection of Mycobacterium marinum is a common disease in pond-cultured Chinese soft shell turtles, especially in those surviving beyond their first year. The infected turtles independently showed either heterophilic or histiocytic granulomas in various organs such as the spleen, liver, lungs, intestine, kidneys, stomach and pancreas. The heterophilic granuloma contained many acid-fast unbranching bacilli intracellularly in macrophages and extracellularly in the necrotic center. The histiocytic granuloma had only a few bacteria, mainly in the cytoplasm of Langhan's giant cells. The organisms were rarely observed in the advanced lesions of both types. Based on PCR assays for partial hsp65 gene of Mycobacterium spp., all of our strains were identified as M. marinum which can be divided into two groups. The strains of the first group induced heterophilic granulomas and had very high nucleotide sequence identities (99.8%–100%) to the reference strains of M. marinum ( AF456471 ) and M. pseudoshottsii ( AY550226 ). Those strains of the second group caused histiocytic granulomas and also showed very high identities (99.8%–100%) to the reference strains of M. marinum ATCC 927 ( AF456470 ) and M. shottsii ( AY550225 ). However, when we compared the partial sequence of the hsp65 gene from group one and two strains the identities between the two groups range from 98.8% to 99.3%, therefore we can not assert that these two belong to the same species.

A stopped-flow manifold was developed to assay and characterize immobilized tannase (EC 3.1.1.20). The immobilized enzyme reactor was inserted within the tube-type electrode pair (cell constant = 103.2 cm− 1) for a real-time conductometric measurement. Tris buffer (2 mM, pH = 7.0) was used as the carrier for sensitivity improvement. The activities and kinetic parameters (Km values) for propyl gallate, methyl gallate and tannic acid were investigated.

This study investigated characteristics of a chitosan membrane from the carapace of the soldier crab Mictyris brevidactylus intended to construct an amperometric biosensor. Electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) were used in this study to characterize these chitosan membranes intended for constructing enzymatic biosensors. Chitosan membranes suffering various durations (10 min) of deacetylation had small charge-transfer resistances (7.88 kohms) but large double-layer capacitances (0.55 microF). They were found in EIS where both the solution resistance and Warburg impedance upon electrode interface were almost independent of the durations and degree of deacetylation. The degree of deacetylation and the thickness of chitosan membranes were also determined. Membrane thickness was slightly dependent with the duration but degree of deacetylation was slightly dependent on the duration. Chitosan membranes with various thicknesses suffered various durations of deacetylation, but this did not influence their electrochemical characteristics. The chitinous membrane was covalently immobilized with glucose oxidase (EC 1.3.4.3) and then attached onto the platinum electrode of a homemade amperometric flow cell. Sensor signal was linearly related to glucose concentration (r=0.999 for glucose up to 1.0 mM). The system was sensitive (S/N5 for 10 microM glucose) and reproducible (CV1.3% for 50 microM glucose, n=5).

In creating a hole on brittle materials by double-side sand blasting, the rebounding sand particle flux during the process may result in underetching at the edge of the mask opening, and leads to a larger sized fluid hole than the desired one. Determination of the correct mask opening size was made mainly by trial and error in the past. In this paper, relationships between the mask opening size and desired size of a hole on both the front and the back sides of the substrate are derived. For the front side, by taking into account the underetching effect, an equation is derived based on the kinetic energy theory. For the back side, there is negligible rebounding sand particles, and the mask opening size is set to be equal to the desired size of the hole. Experiments were conducted to verify the derived relationships. It is found that the measured sizes of the eroded holes on both the front and the back sides of the wafer substrate are distributed normally. The desired hole sizes deviate slightly from the median of a normal distribution curve, and the maximum predicted errors are 2.4% and 3.0% for front side and the back side sand blasting, respectively. The very satisfactory result together with ANOVA and test of homogeneity of variance of the predicted errors for various hole size shows that the derived relationships is applicable for determination of the mask opening size in the sand blasting process.

The path-planning problem is presented to show a car of any desired shape moving from a starting position to a destination in a finite space with arbitrarily shaped obstacles in it. In this paper, a new chain-code representation is developed to record the motion path when forward and backward movements are allowed. By placing the smooth turning-angle constraint, we can obtain more realistic results to the actual motion of cars. Meanwhile, by combining rotational mathematical morphology and distance transformation, we can obtain the shortest collision-free path. As soon as the distance map and the collision-free codes have been established offline, the shortest paths of cars starting from any location toward the destination can be promptly obtained online. Experimental results show that our algorithm works successfully in different conditions. We also extend our algorithm to the automated parallel parking and three-dimensional path planning.

A new test is proposed for testing the validity of the logistic regression model based on case–control data. The proposed test does not need a partition of the space of explanatory variables to handle the case of nonreplication. The new test is consistent against very general alternatives. The asymptotic distribution of the test statistic under a sequence of local alternatives is derived so that the behavior of the asymptotic power function of the new test can be studied. This result also gives the approximated null distribution of the test statistic. For practical sample sizes, the adequacy of the large-sample approximation to the null distribution of the test statistic are carefully examined. Power comparisons with other goodness-of-fit tests are performed to show the advantages of the new method. The test statistic is very simple to compute and the new test will be illustrated with examples.

A colorimetric method and a capillary electrophoresis procedure were developed for quantifying histidyl-leucine and hippurate, respectively. The colorimetric method is sensitive (extinction coefficient = 7.5 mM(-1) cm(-1)) and reproducible (CV = 1.7%, n = 5), which is based on a selective chromogenic reaction for histidyl-leucine (lambda(max) = 390 nm) using o-phthalaldehyde. For samples containing unusually high levels of histidine and/or histidyl peptides, the separation-based approach is preferable. The capillary electrophoresis method makes use of an in-capillary microextraction technique; complicated samples can be measured in less than 4 min without pretreatment. Protocols using both methods to measure angiotensin converting enzyme inhibitory activity were proposed.

A non-imaging focusing heliostat for effective use of thermal solar energy is proposed. The heliostat consists of a number of grouped slave mirrors, which are able to move according to a proposed formula to eliminate the first order aberration. The master mirror tracks the sun by a proposed rotation-elevation mode to project solar rays together with the rest of slave mirrors into a fixed target. The merit of this design is that it may benefit the use of solar energy in high temperature applications by allowing a single stage collector to replace a conventional double stage structure; it may also benefit high concentration applications, e.g., solar powered Stirling engines, solar pumped lasers, etc. The feasibility and a reliability test of the proposed method by a prototype heliostat in the University of Technology, Malaysia is reported.