Elliptical Region Research Articles

Quantitative analysis of carbaryl and thiabendazole in complex matrices using excitation-emission fluorescence matrices with second-order calibration methods

In this paper, a fast and efficient analytical strategy was proposed that chemometrics assisted with excitation-emission fluorescence matrices was used to quantify carbaryl (CAR) and thiabendazole (TBZ) in peach, soil and sewage. Even if there are serious overlapped peaks and unknown interferences in fluorescence analysis, the second-order calibration method based on alternating trilinear decomposition (ATLD) algorithm can be used to analyze CAR and TBZ in peach, soil and sewage. The recoveries of CAR and TBZ in peach are 110.4% and 99.7% and their standard deviations are lower than 2.1% and 0.3%, respectively. In addition, the accuracy of the method was assessed with figures of merit as well as intra-day and inter-day precision. The limit of detection, the limit of quantitation of CAR and TBZ in peach are 1.2 ng mL−1 and 0.3 ng mL−1, 3.5 ng mL−1 and 0.8 ng mL−1, respectively. And their root-mean-square error of prediction are 17.0 ng mL−1 and 5.0 ng mL−1 and there are high sensitivity and selectivity in this method. Meanwhile, the results obtained by ATLD algorithm were compared with those obtained by the self-weighted alternate trilinear decomposition algorithm (SWATLD) and the parallel factor analysis (PARAFAC) algorithm, and statistical methods such as the t-test, F-test and the elliptic joint confidence region were used to evaluate for analysis. There were no significant differences among these methods. At last, high performance liquid chromatography-fluorescence detector (HPLC-FLD) was used to evaluate the accuracy and reliability of the proposed method. These results are satisfactory and indicate that the proposed method can be used for accurate and rapid determination of pesticides in complex systems.

Opportunistic use of “follow-up” chest and abdominal computed tomography in the assessment of bone mineral density of breast cancer patients in a resource-poor nation

Background: Breast cancer patients experience bone loss from treatment-induced menopause, as well as from the direct effect of cancer. The use of computed tomography (CT) attenuation values of the lumbar spine to estimate bone mineral density has been validated by several studies. Materials and Methods: This was a retrospective study conducted at Sweden Ghana Medical Centre and Korle Bu Teaching Hospital between June 2016 and August 2019. Measurement of Hounsfield unit (HU) of lumbar vertebrae was achieved by drawing an elliptical region of interest (ROI) on an axial image of the vertebra about 2–3 mm from the spinal cortical bone. The mean HU of the ROI was measured on bone window for each of the vertebral bodies, and the values were documented and analyzed. Results: The mean bone densities of the vertebrae were generally higher for the noncancer patients compared to the breast cancer patients for all the age groups. The measured bone densities showed a normal distribution curve. The range of bone density for osteopenia and osteoporosis was between 174.4 and 236.4 HU and <174.4 HU, respectively. A Pearson's correlation analysis between patient age and bone density for both groups showed a negative statistically significant relationship. Conclusion: Using CT attenuation values of lumbar vertebra to estimate bone density established that the bone densities follow a normal distribution, the mean bone density for breast cancer patients were slightly lower than for noncancer patients, and age correlated better with lumbar bone density in noncancer patients than in breast cancer patients.

Effect of Heat Transfer on Newtonian Flow Between Concentric Elliptical Regions

In the present study, the slow and steady flow of Newtonian fluid in the presence of heat transfer in annular region formed by two concentric ellipses is considered. The concentric ellipses in z-plane are mapped to concentric circles in ζ-plane using conformal transformation. Analytical solutions for velocity and temperature are obtained in ζ-plane and the same are graphically depicted. The effects of dimensionless parameter such as Grashof number Gr, heat flux β, initial temperature at wall of inner ellipse θ0 and area of cross section of concentric ellipses on velocity, rate of flow and temperature have been studied. The graphical representation shows that the velocity, temperature is enhanced with increase in Gr and area of cross section between ellipses, and decreases with increase in heat flux β.

Distinguishing Weak and Strong Hydrogen Bonds in Liquid Water-A Potential of Mean Force-Based Approach.

The ability to form hydrogen bonds is one of the most important factors behind water's many anomalous properties. However, there is still no consensus on the hydrogen bond structure of liquid water, including the average number of hydrogen bonds in liquid water. We use molecular dynamics simulations of the polarizable iAMOEBA water model for investigating the hydrogen bond characteristics of liquid water over a wide range of temperatures and pressures. Geometric definitions of a hydrogen bond often use a rectangular region on the plane of hydrogen bond distances and angles. In this work, we find that an elliptical region is more appropriate for the identification of hydrogen bonds, based on statistically favorable molecular configurations. The two-dimensional potential of mean force (PMF) landscape along the hydrogen bond distance (O-H) and angle (O-H-O) is calculated for identifying the statistically favored molecular configurations, which is then used for defining hydrogen bond formation as well as the strength of a hydrogen bond. We further propose a new approach to characterize the hydrogen bonds as strong when the PMF is lower than -2 kT. Using this definition, a consistent explanation for the different average numbers of hydrogen bonds in water is obtained in agreement with the literature. Simulations are also performed with the rigid and nonpolarizable TIP4P/2005 water model. Both water models are qualitatively consistent in predicting the distribution of double-, single-, and non-donor configurations, in line with experimental data, while the iAMOEBA water model yields more quantitatively precise results, including a 10-15% double-donor fraction at 90 °C and 1 atm. The method is also demonstrated to be applicable to the recent, and more general, three-dimensional PMF-based definition of hydrogen bonds.

Improved quantification of N-methylcarbamates combining supramolecular post-column derivatization-fluorescence detection-high performance liquid chromatography and partial least squares analysis

A strategy to improve the simultaneous quantification of N-methyl-carbamate pesticides was performed. It takes advantage of the supramolecular interactions between the analytes and hydroxypropyl-β-cyclodextrin (HPCD) in the post-column reactor to increase the high-performance liquid chromatography-fluorescence sensitivity and use the partial least squares algorithm for the data analysis to identify strong overlap signals. The use of HPCD in the derivatization reactor generated a 50% of improvement in the limit of detection of Aminocarb (11.29 ng/ mL), Carbofuran (CF) (19.58 ng/mL) and, Bendiocarb (BC) (0.27 mg/mL). It practically was the same for Carbaryl (2.35 ng/mL), but with a precise identification between CF and BC. The methods developed for these analytes were exactly on the elliptic joint confidence region. The recoveries in domiciliary water indicate the accuracy of the methodologies developed with values between 97% and 103% at the maximum concentration levels allow by international recommendations..

Detonation of a Combustible Gas Mixture during the Interaction of a Shock Wave with an Elliptical Region of a Heavy Inert Gas

Detonation of a Combustible Gas Mixture during the Interaction of a Shock Wave with an Elliptical Region of a Heavy Inert Gas

Momentless design of variable stiffness composite cylindrical vessels with elliptical heads

Membrane stress state is favorable for pressure vessels to resist internal pressure since the stress through shell thickness is constant. However, bending stresses resulted from bending moments of pressure vessels will destroy the favorable membrane stress state leading to nonuniform stress through shell thickness. Thus, suppressing bending moments in pressure vessels will be an efficient way to achieve improvement of load carrying capacity. A momentless design of variable stiffness composite cylindrical vessels with elliptical heads which are widely used in engineering has been presented in this study. The momentless governing equations concerning both the elliptical head and junction region of the pressure vessels under uniform pressure are derived. Numerical analyses are carried out on the pressure vessel models with different configurations. The variable angles of fiber orientations over these models are explicitly provided. The stress resultants and deformation behaviors together with the curvature changes of these models have been checked and compared. Results show that based on the variable fiber angles over the structure obtained from the presented mathematical design methodology, the bending moments are successfully suppressed in the variable stiffness composite pressure vessels. The momentless design method will ensure the pressure vessels to service in an efficient membrane state.

Ensemble Kalman filter for vortex models of disturbed aerodynamic flows

The task of dynamic flow estimation is to construct an approximation of an evolving flow---and particularly, its response to disturbances---using measurements from available sensors. Building from previous work by Darakananda et al.~(Phys Rev Fluids 2018), we further develop an ensemble Kalman filter (EnKF) framework for aerodynamic flows based on an ensemble of randomly-perturbed inviscid vortex models of flow about an infinitely-thin plate. In the forecast step, vortex elements in each ensemble member are advected by the flow and new elements are released from each edge of the plate; the elements are aggregated to maintain an efficient representation. The vortex elements and leading edge constraint are corrected in the analysis step by assimilating the surface pressure differences across the plate measured from the truth system. We show that the overall framework can be physically interpreted as a series of adjustments to the position and shape of an elliptical region of uncertainty associated with each vortex element. In this work, we compare the previously-used stochastic EnKF with the ensemble transform Kalman filter (ETKF), which uses a deterministic analysis step. We examine the response of the flat plate at $20^\circ$ in two perturbed flows, with truth data obtained from high-fidelity simulation at Reynolds number 500. In the first case, we apply a sequence of large-amplitude pulses near the leading edge of the plate to mimic flow actuation. In the second, we place the plate in a vortex street wake behind a cylinder. In both cases, we show that the vortex-based framework accurately estimates the pressure distribution and normal force, with no {\em a priori} knowledge of the perturbations. We show that the ETKF is consistently more robust than the stochastic EnKF. Finally, we examine the mapping from measurements to state update in the analysis step through SVD of the Kalman gain.

Thermoelastic response of a nonhomogeneous elliptic plate in the framework of fractional order theory

This article aims to examine the thermoelastic problem for a medium with nonhomogeneous material properties within a finite-length elliptical plate. An analytical method is established under the assumption that the thermomechanical material inhomogeneity obeys the product form of power and exponential functions through the plate's thickness. At the same time, calorific capacity and Poisson's ratio are assumed to be constant. The fractional time derivative heat conduction differential equation with an internal heat source is solved using integral transformation technique in terms of generalized Laguerre polynomial, and Mathieu function in the Laplace domain. The Gaver–Stehfest approach is used to invert Laplace domain outcomes. The convergence of infinite series solutions has been discussed. In the specific case, the elliptic region that degenerates into the problem of the circular area by adding limiting conditions is also considered. As a numerical example, the temperature, displacement and thermal stress distributions are calculated, taking into account influence of inhomogeneity, and the numerical results are graphically demonstrated.

Initial evaluation of dual-energy computed tomography as an imaging biomarker for hepatic metastases from neuroendocrine tumor of the gastrointestinal tract.

To evaluate quantitative iodine parameters from the arterial phase dual-energy computed tomography (DECT) scans as an imaging biomarker for tumor grade (TG), mitotic index (MI), and Ki-67 proliferation index of hepatic metastases from neuroendocrine tumors (NETs) of the gastrointestinal (GI) tract. Imaging biomarkers have the potential to provide relevant clinical information about pathologic processes beyond lesion morphology. NETs are a group of rare, heterogeneous neoplasms classified by World Health Organization (WHO) TG, which is derived from MI and Ki-67 proliferation index. Imaging biomarkers for these pathologic features and TG may be useful. Between January 2014 and April 2019, 73 unique patients with hepatic metastases from NET of the GI tract underwent DECT of the abdomen with an arterial phase were analyzed after exclusions. Using GSIViewer software (GE Healthcare, Madison, Wisconsin), elliptical regions of interest (ROIs) were placed over selected hepatic metastases by a fellowship trained abdominal radiologist. Quantitative iodine concentration (IC) data was extracted from the lesion ROIs, and the normalized IC (lesion IC/aorta IC) and relative IC (lesion IC/liver IC) for each liver were calculated. Spearman correlation was calculated for lesion mean IC, normalized IC, and relative IC to both Ki-67 proliferation and mitotic indices. Student's t-test was performed to compare lesion mean IC, normalized IC and relative IC between WHO TGs. There was very weak correlation between both normalized IC and relative IC for both Ki-67 proliferation and mitotic indices. A significant difference was not observed between normalized IC and relative IC to distinguish metastases from G1 and G2/3 tumors. Our study finds limited potential for quantitative parameters from DECT to distinguish neuroendocrine hepatic metastases by WHO TG, as well as limited potential as an imaging biomarker for Ki-67 proliferation and mitotic indices in this setting. Our findings of a lack of correlation between Ki-67 and quantitative iodine parameters stands in contrast to existing literature that reports positive correlations for these parameters in the rectum and stomach.

Cermet materials reinforced with a small addition of spinel nanoparticles for molten salt power systems

This work is devoted to developing of new cermets for molten-salt power systems, promising for use in aviation, rocket and space technology, and power engineering. The production of cermets in the nickel-aluminum alloy system - 35 wt. % aluminum oxide by the method of mechanical activation and spark plasma sintering was carried out. It was found that the addition of 5 wt. % yttrium oxide, as well as small quantities (0.1 wt. %) of aluminum-magnesium spinel nanoparticles, increase the strength of the cermet at elevated temperatures. Cermets have high strength at room and elevated temperatures, which amounted to 480-530 MPa at 20 °C and 430-470 MPa at 750 °C. The micro structure of cermets was characterized by the presence of elliptical regions, the grains in which were significantly smaller than the grains in the surrounding matrix. This structure allows to effectively harden the material because elliptical areas are obstacles to crack propagation. Elliptical zones have length ranged 100 to 200 μm and width 5 to 20 μm. It was found that the material of the NiAl-Al2O3 system at 20 °C and 800 °C contains the phases NiAl, Al2O3, and Ni2Al3. Composite composition NiAl-Al2O3-Y2O3 at 20 °C and 800 °C retains the three-phase composition of NiAl, Al2O3, and Y2O3. Both materials are stable up to 800 °C.

Riemann problem for a non-strictly hyperbolic system in chemotaxis

<p style='text-indent:20px;'>The Riemann problem is solved for a system arising in chemotaxis. The system is of mixed-type and transitions from a hyperbolic to an elliptic region. It is genuinely nonlinear in the <inline-formula><tex-math id="M1">\begin{document}$ u $\end{document}</tex-math></inline-formula>-<inline-formula><tex-math id="M2">\begin{document}$ v $\end{document}</tex-math></inline-formula> plane except on the <inline-formula><tex-math id="M3">\begin{document}$ v $\end{document}</tex-math></inline-formula>-axis, where it is linearly degenerate. We have solved the Riemann problem in the physically relevant region up to the boundary of the hyperbolic-elliptic region, which is non-strictly hyperbolic. We also solved the problem on the linearly degenerate region. While solving the Riemann problem, we found classical shock and rarefaction waves in the hyperbolic region and contact discontinuities in the linearly degenerate region.</p>

In vivo measurement of the anisotropic mechanical properties of human skin by indentation test

A novel approach is presented to determine the anisotropic mechanical properties of human skin invivo by indentation method. In this paper, the skin is considered as an anisotropic elastomer due to fiber reinforcement with an additional property of limiting extensibility. The associated theory of indentation method is presented and specialized to the particular case of the constitutive behaviors of skin so as to establish the theory basis of this work. The indentation tests are performed on the inner forearm in the relaxant and uniaxially pre-stretched state, respectively. Different from the conventional indentation tests, a special optical system is used to capture the contact morphology in real time. The results demonstrate that the eccentricity of the elliptical contact region changes with the pre-stretch on the ground that the eccentricity has a dependence on the degree of anisotropy.

New species and records of Anacanthorus (Monogenoidea: Dactylogyridae) from the gills of Brycon amazonicus (Characiformes: Bryconidae) in the Peruvian Amazon.

Five species belonging to Anacanthorus Mizelle & Price, 1965 were found parasitizing the gills of Brycon amazonicus (Agassiz) collected in the Peruvian Amazon: A. spiralocirrus Kritsky, Thatcher & Kayton, 1979, A. femoris n. sp., A. kukamensis n. sp., A. rarus n. sp. and A. sabaloi n. sp. Anacanthorus femoris n. sp. presents a membranous accessory piece with flared tip, hooks with proximal bulbous base containing 1 translucent region; A. kukamensis n. sp. presents an accessory piece with two branches, one with can-opener-shaped termination and the other with denticles in the lateral margin and at both ends of the distal portion, hooks with expanded proximal bulbous base with central and elliptical translucent region; A. rarus n. sp. presents a MCO as a long sclerotized tube, slightly sinuous, with folds in its middle region, with proximal region with circular opening and distal region with rough termination. The accessory piece is small and curved, hooks with expanded proximal bulbous base with central, elliptical translucent region, elongate shank, truncate thumb, slightly curved shaft and inconspicuous point; in A. sabaloi n. sp. the MCO is a long sclerotized reflexive tube, with membranous appearance from its middle part towards the end, with distal and proximal end with an inwardly directed fold, the accessory piece is a membranous sheath that envelops the MCO just before the reflection zone. The four new species found in this study are the second records of species of Anacanthorus described from a fish host from the Peruvian Amazon.

Roots of generalised Hermite polynomials when both parameters are large

We study the roots of the generalised Hermite polynomials H m,n when both m and n are large. We prove that the roots, when appropriately rescaled, densely fill a bounded quadrilateral region, called the elliptic region, and organise themselves on a deformed rectangular grid, as was numerically observed by Clarkson. We describe the elliptic region and the deformed grid in terms of elliptic integrals and their degenerations.

Substitution of satellite-based land surface temperature defective data using GSP method

Land surface temperature (LST) as an important environmental variable provides valuable information for earth environmental system modelling. Currently, LST is obtained through satellite thermal sensors at various spatial and temporal resolutions. Although spatially continuous satellite-based LST measurements are intended to overcome the shortcomings of sparse ground-based LST measurements, LST images often contain anomalous values due to the existence of clouds or sensor malfunctioning. The problem becomes more serious where the users deal with high spatial resolution characterized by low temporal resolution. This study examines the capability of a newly developed graph signal processing (GSP) method using two-dimensional single-date thermal data. For this purpose, four Landsat/TIRS datasets are analyzed. The data of five elliptical regions on thermal images are eliminated and then reconstructed through the GSP method and using the LST values of the enclosing rectangles containing the ellipsoids. The results indicate that the temperature variation determined by the GSP method generally conforms to the original image LST values. According to a correlation test conducted on the original image LST and those obtained through the GSP method, the values vary from 58% to 95%, which is an above-the-average rate (RMSE from 0.69 to 2.27). The statistical analysis of the original image LST in both the elliptical regions and the enclosing rectangles containing the ellipsoids indicates that an increase in the variance of LST data causes an increased error in the calculation of temperature by the GSP method, and vice versa. The results of the analysis of variance (ANOVA) and Duncan test indicated that an increase in the number of the non-zero spectral bins would result in increased RMSE values for all the dates and the regions. Moreover, the model errors were significant at the 0.05 level across all the image date and five elliptical study regions. Based on the results, the use of this method is recommended for the reconstruction of LST missing values, where dissimilarity of atmospheric conditions limits the use of other methods that depend on the time series data of various dates and a great deal of data calculation.

The Riemann Problem with Phase Transitions for Fluid Flows in a Nozzle

Phase transitions in a model of van der Waals fluid flows in a nozzle with discontinuous cross-sectional area are investigated. The model admits a physically unstable elliptic region which causes phase transitions, and a jump in cross-sectional area which causes stationary contact waves. Compositions between waves in different characteristic fields are constructed differently in subsonic or supersonic regions. A new kind of waves is introduced which helps establish the existence of solutions of the Riemann problem. There are regions in which the Riemann problem admits a unique solution. Resonant phenomena occur when shock waves associated with different characteristic fields propagate with the same speed. Multiple solutions are also observed even in a strictly hyperbolic region not only by the modeling, but also by the type of a van der Waals fluid.

Three efficient chemometrics assisted fluorimetric detection methods for interference-free, rapid, and simultaneous determination of ibrutinib and pralatrexate in various complicated biological fluids

In this study, a series of green, interference-free fluorimetric detection methods of the excitation-emission matrix coupled with the second-order calibration methods were proposed for the determination of ibrutinib and pralatrexate in various complicated biological fluids. The second-order advantage of the proposed method can overcome the problem of poor selectivity caused by the wide spectra of the fluorescence method. Even in the presence of uncalibrated interferences and severe peak overlap, the signal of pure substance and accurate quantitative results were still obtained. The average recoveries of the three methods were 94.5–104.9% for Alternating Trilinear Decomposition (ATLD) algorithm, 95.5–105.8% for Alternating Normalization Weighted Error (ANWE) algorithm and 94.4–105.7% for Parallel Factor Analysis (PARAFAC) algorithm, respectively. For ATLD, ANWE and PARAFAC, the relative standard deviations (RSD) were lower than 9.2%, 6.8% and 9.2%, and the RMSEPs were less than 8.1, 8.4 and 8.6 ng mL−1, respectively. In addition, the elliptic joint confidence region (EJCR) was adopted to further prove the accuracy of the three methods. The results showed that the three methods can accurately be quantified without significant difference. Good figures of merit parameters were also obtained. Among them, the limit of detection (LOD) and limit of quantification (LOQ) of ibrutinib and pralatrexate were in the range of 0.11–0.76 ng mL−1 and 0.21–1.12 ng mL−1, respectively, which were lower than the corresponding blood concentrations. These results indicate that the proposed method provides a promising, alternative and universal analysis strategy for clinical drug monitoring.

Подбор вектора признаков для процедуры MeanShift

The article gives the description of the feature vector, which is suitable for the MeanShift procedure, uses all the color information of the RGB24 format and has a dimension exceeding only 1.5 times the dimension of the smallest 512-dimensional vector used for the Kernel Based Object Tracking procedure. For the described feature vector, a function of similarity of two elliptical areas of the frame is built. For the similarity function, formulas are found for the gradient vector - the mean shift vector, which indicates the direction of the growth of similarity in four-dimensional space of all elliptical regions covering the object in the frame. Knowing the greatest value of the similarity function of two elliptical regions, the length of the displacement vector in the four dimensional space of all elliptical regions was found. To this vector the previous point in space must be moved at the current moment, i.e. the values of the coordinates of the center and the dimensions of the ellipse, in order to obtain the best similarity of the current elliptical area from the previous one. Finally, so as to implement Kernel Based Object Tracking, an algorithm of successive iterations (Newton's method) has been developed, which allows finding the parameters of the ellipse that really has the best similarity. The experiments were carried out and their results were presented and discussed

Optimum design for permittivity of dielectric absorbing materials

In the design of absorbing materials, investigating the ideal value range of electromagnetic parameters under given conditions and adjusting the electromagnetic parameters by existing materials to achieve the ideal range need are two important issues to be solved. Based on transmission line theory and Debye theory, numerical simulations are used to explore the ideal value range of various parameters of absorbing materials under different conditions as well as their selection laws. The Cole-Cole diagram based on combining theory and experiments was given for optimizing design of absorption performance. When the thickness and reflection attenuation rate of the material are presupposed, the real and imaginary parts of the corresponding ideal permittivity should form an approximately elliptic curve. When the permittivity of the material is in the elliptical region, the reflection attenuation rate is lower than its given value. Ellipses with lower reflection attenuation locate in ellipses with higher reflection attenuation, but the centers of the ellipses do not coincide. As the reflection attenuation rate decreases, the corresponding ellipse area shrinks sharply, and the range of electromagnetic parameters becomes rigorous.