Production Cross Research Articles

A classification of triharmonic hypersurfaces in a pseudo-Riemannian space form

The purpose of this article is to investigate triharmonic hypersurfaces Mtn in a pseudo-Riemannian space form Nt1n+1(c). Assuming that the shape operator is diagonalizable, we show that every CMC triharmonic hypersurface either has constant scalar curvature or it is minimal if cε>0 and every CMC triharmonic hypersurface is minimal if cε<0, where ε is the inner product of the unit normal vector of Mtn. Furthermore, we prove that any CMC triharmonic hypersurface with diagonalizable shape operator in a pseudo-Euclidean space Et1n+1 is actually minimal provided that zero is a principal curvature of multiplicity at most one.

Reflective conditions for radiative transfer in integral form with H-matrices

In a recent article the authors showed that the radiative Transfer equations with multiple frequencies and scattering can be formulated as a nonlinear integral system. In the present article, the formulation is extended to handle reflective boundary conditions. The fixed point method to solve the system is shown to be monotone. The discretization is done with a P1 Finite Element Method. The convolution integrals are precomputed at every vertex of the mesh and stored in compressed hierarchical matrices, using Partially Pivoted Adaptive Cross-Approximation. Then the fixed point iterations involve only matrix vector products. The method is O(NN3ln⁡N), with respect to the number of vertices, when everything is smooth. A numerical implementation is proposed and tested on two examples. As there are some analogies with ray tracing the programming is complex.

Optimization of the iot network protocol choozing for monitoring audio information

The subject of research is the choice of a protocol in the Internet of Things (IoT) network for monitoring and analyzing audio information. The purpose of the article is to optimize the process of choosing a protocol for monitoring audio information based on IoT and evaluate the results. The authors have developed an IoT framework for monitoring and analyzing audio and voice information. The IoT network includes a sound sensor (microphone), a unit for analyzing the information received from it and a decision-making module. The description of protocols in the IoT network for assessing the sound level is given: the Wireless USB standard, the narrowband standard of the NB-IoT.The hierarchy analysis method was used to select the best protocol. The methodology and its main formulas for calculating the best option are given. A table of the four selected protocols for the IB network is given. As characteristics of the protocols, the following are considered: downlink speed, latency, device bandwidth, device transmission power. A matrix of paired comparisons of protocol parameter indicators based on expert assessments has been formed. Four matrices of paired comparisons of transmission standards variants in relation to the indicator of speed, delay, bandwidth of devices, transmission power of devices are constructed. Calculations of local vectors and priority vectors of quality indicators were performed for these four matrices. Then the matrix of vectors of global priorities is calculated by calculating the sum of the products of local vectors of matrices of paired comparisons of transmission standards variants on the corresponding priority vectors of quality indicators of the matrix of paired comparisons of protocol parameters. From the results obtained, the best protocol option for the network and sound monitoring was determined by the maximum value.

Assessing the Efficiency and Persistence of African Stock Markets through DEA Score: Evidence from COVID-19 Pandemic

The few studies on COVID-19’s impact on stock market efficiency have reached mixed conclusions. However, the findings lean towards a negative impact, no studies have assessed market efficiency when returns increase in the existing capacity of COVID-19 cases, exchange rates and inflation rates. This study uses data envelopment analysis (DEA) and the DEA-adjusted estimator. We finally adopt the cross and time product ratios to determine the persistence of stock market efficiency. We find that the COVID-19 pandemic severely impacted the efficiency of African stock markets in 2021 and that the efficiency of African stock markets persists only in the short run. These findings are relevant to investors seeking to diversify their portfolios during pandemics and to regulators of African stock markets. Global investors should diversify their portfolios with African stock markets to mitigate the impact of pandemics on their investments. To reap the benefits of diversification, investors should invest in efficient African markets during pandemics and sell stocks in inefficient markets in the short run. In addition, regulators of African stock markets should adopt technologies that aid in the flow of information among investors.

Numerical studies of shock–vortex interaction over a wedge during shock-wave diffraction—A new approach

In this study, shock wave diffraction has been investigated through a numerical simulation of a moving normal shock incident on a sharp-edged wedge. Schardin's problem is revisited using some existing and new mathematical tools. Two-dimensional compressible Navier–Stokes equation is solved using a higher-order version of the rhoCentralFoam solver in the OpenFOAM platform. Overall flow structures are captured with high efficacy. The divergence of the Lamb vector is used to probe the interaction between vorticity bearing and fluid straining motion, which increases dramatically inside the primary vortex after collision with the reflected Mach stem and increases the turbulent kinetic energy (TKE). In the separated shear layer that emerges from the wedge tip, there is a reduction of TKE after the collision between the lambda shock and accelerated shock. The vorticity pumping into the mean flow by the baroclinic torque is dominant in the separated shear layer before the above collision, whereas after collision it is only dominant inside the primary vortex. A new vector M is introduced here, which is the cross product of the vorticity vector and the pressure gradient vector. The divergence of M shows the interaction between the pressure gradient and the vorticity gradient. This interaction affects the separation bubble formed over the base wall of the wedge due to the shock-wave/boundary layer interaction induced by the lambda shock. Dynamic mode decomposition shows a dominant mode at a frequency of 125.7 Hz, which is due to low-frequency shock oscillation.

Scalar products of Bethe vectors in the generalized algebraic Bethe ansatz

Scalar products of Bethe vectors in the generalized algebraic Bethe ansatz

Quantifying Poynting Flux in the Quiet Sun Photosphere

Poynting flux is the flux of magnetic energy, which is responsible for chromospheric and coronal heating in the solar atmosphere. It is defined as a cross product of the electric and magnetic fields, and in ideal MHD conditions it can be expressed in terms of the magnetic field and plasma velocity. Poynting flux has been computed for active regions and plages, but estimating it in the quiet Sun (QS) remains challenging due to resolution effects and polarimetric noise. However, with the upcoming DKIST capabilities, such estimations will become more feasible than ever before. Here, we study QS Poynting flux in SUNRISE/IMaX observations and MURaM simulations. We explore two methods for inferring transverse velocities from observations—FLCT and a neural network–based method DeepVel—and show DeepVel to be the more suitable method in the context of small-scale QS flows. We investigate the effect of azimuthal ambiguity on Poynting flux estimates, and we describe a new method for azimuth disambiguation. Finally, we use two methods for obtaining the electric field. The first method relies on an idealized Ohm’s law, whereas the second is a state-of-the-art inductive electric field inversion method PDFI_SS. We compare the resulting Poynting flux values with theoretical estimates for chromospheric and coronal energy losses and find that some of the Poynting flux estimates are sufficient to match the losses. Using MURaM simulations, we show that photospheric Poynting fluxes vary significantly with optical depth, and that there is an observational bias that results in underestimated Poynting fluxes due to an unaccounted shear term contribution.

Significant Differences in Capsid Properties and Potency Between Adeno-Associated Virus Vectors Produced in Sf9 and HEK293 Cells.

For successful vector-based gene therapy manufacturing, the selected adeno-associated virus (AAV) vector production system must produce vector at sufficient scale. However, concerns have arisen regarding the quality of vector produced using different systems. In this study, we compared AAV serotypes 1, 8, and 9 produced by two different systems (Sf9/baculovirus and HEK293/transfection) and purified by two separate processes. We evaluated capsid properties, including protein composition, post-translational modification, particle content profiles, and in vitro and in vivo vector potency. Vectors produced in the Sf9/baculovirus system displayed reduced incorporation of viral protein 1 and 2 into the capsid, increased capsid protein deamidation, increased empty and partially packaged particles in vector preparations, and an overall reduced potency. The differences observed were largely independent of the harvest method and purification process. These findings illustrate the need for careful consideration when choosing an AAV vector production system for clinical production.

Determination of uncertainty of coordinate measurements on the basis of the formula for EL,MPE

A technique of estimating the uncertainty of coordinate measurements, called the sensitivity analysis method according to ISO/TS 15530-1, developed at University of Bielsko-Biała, is presented. Measurement uncertainty is estimated on the basis of information contained in the formula for the maximum permissible error (EL,MPE) of the applied coordinate measuring system (CMS) and on the basis of its acceptance or reverification test results. Measurement models are of the nature of close mathematical dependencies expressing the measured characteristic in the form of a distance which is a function of coordinates differences of a low number of essential points, properly selected on the workpiece. Measurement models for dimensions and various geometrical deviations were developed. Thanks to the applied vector notation the models are in the form of cross and dot products and they are easily programmable in software such as Matlab, Maple or Python. Detailed examples of the uncertainty analysis for two characteristics (position deviations of the axes of the holes in relation to the datum system) of a car steering knuckle are provided.

B-153 Acceleration vs Time Data for Two Pneumatic Tube Specimen Transport Routes: Comparison of Distributions of Jerk (d(acceleration)/dt) and Theta (Change in Angle)

Abstract Background As part of a Quality Assurance investigation regarding specimen integrity, we had occasion to compare properties of pneumatic tube transport (PTT) of specimens between a collection site of origin and two different laboratory destinations. We obtained acceleration vs time data using an accelerometer. Borrowing from public transportation safety literature, we examined these profiles in terms of distributions of jerk, which is the first derivative of acceleration (d(acceleration)/dt ≡ g/s), and distributions of theta, the angle between successive acceleration vectors. Methods Primary data for acceleration vs time were collected using a USB accelerometer (X16-1E, Gulf Coast Data Concepts LLC, Waveland, MS). The device produces a CSV file for acceleration along 3 mutually orthogonal axes in three dimensions (x, y, and z) as a function of time (rate = 12 Hz). For data collection, the device was wrapped in bubble wrap and placed within a PTT carrier. Data were collected for transport from the collection site to destination laboratory 1 (Route A), and from the collection site to destination laboratory 2 (Route B). Each acceleration datapoint represented a 3-dimenstional vector (having both magnitude and direction). We calculated jerk as the magnitude of the vector representing the difference in the acceleration vectors between successive data points. We calculated angular changes in direction of acceleration (theta) from the dot product of successive acceleration vectors. Variation in theta may be thought of as a measure of “rattling”. Results Routes A and B had practically identical transit times of approximately 300 s (5 min). Accelerations ranged in magnitude (M) from 0–8 g. Route A demonstrated a 2 min interval of essentially constant velocity, whereas Route B demonstrated nearly continuous variation in acceleration. For Route B, M &amp;gt; 1.2 g comprised 29.0% of results compared to 13.5% of results for Route A (ratio = 2.1). Jerk ranged from 0 to 7 g per time interval of 1/(12 Hz). For Route B, jerk &amp;gt; 0.1 g per time interval comprised 63.0% of results compared to 28.3% of results for Route A (ratio = 2.2). Theta ranged from 0 to 180 degrees. For Route B, theta &amp;gt; 5 degrees comprised 59.3% of results compared to 26.6% of results for Route A (ratio = 2.2). By measures of acceleration, jerk, and theta, Route B is a “rougher” ride for specimens compared to Route A. The similarity of the ratios given above (range 2.1–2.2) indicate that differences in acceleration, jerk, and theta run in parallel as variables for comparison between these two PTT routes. Conclusions In transportation safety literature, jerk is a primary variable in the category of “conditions in which people get knocked down.” For specimen transport, the analogy is that jerk might be a variable with respect to “conditions that may activate or disrupt cells.” In our example, comparisons of distributions for acceleration, jerk and theta ran in parallel. Thus, in evaluation of effects of PTT on test results, analysis of acceleration data alone might mask identification of cumulative effects of jerk and theta as possible primary variables. Experimentally, however, it would be very difficult to establish distinction between acceleration, jerk, or theta as primary variables.

Bioengineered Hybrid Rep 2/6 Gene Improves Encapsulation of a Single-Stranded Expression Cassette into AAV6 Vectors.

The production of clinical-grade recombinant adeno-associated viral (AAV) vectors for gene therapy trials remains a major hurdle in the further advancement of the gene therapy field. During the past decades, AAV research has been predominantly focused on the development of new capsid modifications, vector-associated immunogenicity, and the scale-up vector production. However, limited studies have examined the possibility to manipulate non-structural components of AAV such as the Rep genes. Historically, naturally isolated, or recombinant library-derived AAV capsids have been produced using the AAV serotype 2 Rep gene to package ITR2-flanked vector genomes. In the current study, we mutated four variable amino acids in the conservative part of the binding domain in AAV serotype 6 Rep to generate a Rep2/6 hybrid gene. This newly generated Rep2/6 hybrid had improved packaging ability over wild-type Rep6. AAV vectors produced with Rep2/6 exhibited similar in vivo activity as standard AAV6 vectors. Furthermore, we show that this Rep2/6 hybrid also improves full/empty capsid ratios, suggesting that Rep bioengineering can be used to improve the ratio of fully encapsulated AAV vectors during upstream manufacturing processes.

Enhancing the production of recombinant adeno-associated virus in synthetic cell lines through systematic characterization.

Recombinant adeno-associated virus (rAAV) is among the most commonly used in vivo gene delivery vehicles and has seen a number of successes in clinical application. Current manufacturing processes of rAAV employ multiple plasmid transfection or rely on virus infection and face challenges in scale-up. A synthetic biology approach was taken to generate stable cell lines with integrated genetic modules, which produced rAAV upon induction albeit at a low productivity. To identify potential factors that restrained the productivity, we systematically characterized virus production kinetics through targeted quantitative proteomics and various physical assays of viral components. We demonstrated that reducing the excessive expression of gene of interest by its conditional expression greatly increased the productivity of these synthetic cell lines. Further enhancement was gained by optimizing induction profiles and alleviating proteasomal degradation of viral capsid protein by the addition of proteasome inhibitors. Altogether, these enhancements brought the productivity close to traditional multiple plasmid transfection. The rAAV produced had comparable full particle contents as those produced by conventional transient plasmid transfection. The present work exemplified the versatility of our synthetic biology-based viral vector production platform and its potential for plasmid- and virus-free rAAV manufacturing.

Generalized Split Quaternions and Their Applications on Non-Parabolic Conical Rotations

In this study, we first generalize the Lorentzian inner and vector products, and then we define the generalized split quaternions by means of the generalized Lorentzian inner and vector products. Next, on any hyperboloid of one or two sheets, which is a generalized Lorentzian sphere, non-parabolic conical rotations with nonnull axes are expressed using the generalized split quaternions with supporting numerical examples.

Investigating dynamics of lentiviral vector secretion from HEK293T producer cells using a fractionated perfusion system.

Mammalian cell culture is quickly becoming the go to engineering vehicle to mass produce viral vectors in a manner that is safe, convenient, reproducible, and cost and scale effective. Human embryonic kidney (HEK293) cells, in particular, have been utilized and customized (via differentiated transgene expression, modified culture parameters, addition of cytostatic culture agents) to increase vector yields. However, less attention has been made to understanding innate processes within the cells (such as, immune response, cell cycle, metabolism) themselves to better control or increase viral vector product yield. Accordingly, herein, the variation in viral production was studied from HEK cells over time using a one-way perfusion system and bioreactor to study the impact of external factors on secretion dynamics without retrotransduction. Specifically, the impact of cell density on viral titer, transduction efficiency, and LDH, was studied. Next, we look at the impact of using an inflammatory reporter cell line on viral output, and the secretion dynamics from HEK cells when we use sodium butyrate (cell cycle arrest agent). Lastly, we assess how downregulation of the PDK pathway increases viral titer. Altogether, we investigated the impact of various interventions to increase transient protein expression and viral output from HEK cells in a controlled and measurable environment to ultimately increase the efficiency of HEK cells for downstream clinical applications.

Initial antimicrobial therapy and case fatality in patients with community-acquired pneumonia

The health importance of community-acquired pneumonia is an unquestionable fact given its relationship with hospital and overall mortality. The objective of the investigation was to evaluate the relationship between selected antimicrobials used in the initial treatment (amoxicillin/sulbactam, cefuroxime, ceftriaxone and cefotaxime) and mortality from pneumonia. An observational study was carried out, with a descriptive design and a population of 1,809 patients with pneumonia hospitalized between 2012 and 2019; the necessary information was obtained from the clinical history. Statistical processing was performed using bivariate and multivariate analysis (logistic regression); the ratio of cross products (odds ratio) and its 95% confidence interval were used as a statistician. Among the results, the following stand out: significantly higher lethality values were found in those treated with cefotaxime (33%) than in those who received amoxicillin/sulbactam (24%, OR 1.6[1.0001;2.6]), as well as in those treated with ceftriaxone (30%) compared with those treated with amoxicillin/sulbactam (24%, OR 1.3[1.05;1.8]) and with cefuroxime (24%, OR 1.3[1.04;1.7]). A higher frequency of patients with extensive pneumonia, of patients in a critical state on admission, and of bedridden occurrence during hospitalization were identified in those treated with cefotaxime. In patients with “moderate pneumonia and high probability of unfavorable outcome”, treatment with ceftriaxone or cefotaxime was associated with death; as well as ceftriaxone treatment for all subjects. It is concluded that the initial treatment with amoxicillin/ sulbactam or cefuroxime was more favorable than the use of third generation cephalosporins. Also in the global analysis, the absence of differences in lethality between those treated with amoxicillin/sulbactam and with cefuroxime was recognized.

Use of differential forms in the determination of divergence of cross products of tensors in nonlinear solid mechanics

AbstractWe consider the cross product of tensors introduced by R. de Boer (1982) and used by J. Bonet et al. (2016) in describing problems from nonlinear solid mechanics. From the paper by J. Bonet et al., it appears that the cross product of tensors can be used to rearrange the mechanical descriptions and significantly simplify the expressions of selected mechanical quantities encountered in the description of mechanical problems in solid mechanics with large strains. In this paper, we derive some additional properties of the cross product of tensors, which also allow some simplifications of selected mechanical quantities. In particular, we establish a connection between the cross product of operators and differential forms introduced by M. Spivak (1971, 1999). These connections allow further generalization of some expressions. At this point, we take advantage of the important fact that the second differentials of differential forms are zeros. This fact allows further simplification of certain expressions and opens up further new possibilities in the description of mechanical problems in nonlinear solid mechanics.

Promoter Optimization Circumvents Bcl-2 Transgene-Mediated Suppression of Lentiviral Vector Production.

Lentiviral vectors are a robust gene delivery tool for inducing transgene expression in a variety of cells. They are well suited to facilitate the testing of therapeutic candidate genes in vitro, due to relative ease of packaging and ability to transduce dividing and non-dividing cells. Our goal was to identify a gene that could be delivered to the heart to protect against cancer-therapy-induced cardiotoxicity. We sought to generate a lentivirus construct with a ubiquitous CMV promoter driving expression of B-cell lymphocyte/leukemia 2 gene (Bcl-2), a potent anti-apoptotic gene. Contrary to our aim, overexpression of Bcl-2 induced cell death in the producer HEK293T cells, resulting in failure to produce usable vector titre. This was circumvented by exchanging the CMV promoter to the cardiac-specific NCX1 promoter, leading to the successful production of a lentiviral vector which could induce cardioprotective expression of Bcl-2. In conclusion, reduced expression of Bcl-2 driven by a weaker promoter improved vector yield, and led to the production of functional cardioprotective Bcl-2 in primary cardiomyocytes.

Status and Regulation of the Fintech Industry

Fintech is the cross product of the financial industry and the technology industry. With the development of society, financial digitization and technology finance have become the development trend. Electronic payment, p2p lending, Robo-Advisor and block chain technology four industries have formed a scale. The current fintech industry has become an important supplement to the economic system. However, due to the short development time, there are still challenges such as high risk points and difficult supervision. Based on the existing industrial scale and business capacity, the continuous integration of fintech industry and society has become a future trend. In the long run, fintech enterprises should give full play to their advantages in technology reserve, optimize and improve products, maintain industry self-discipline and reduce risks. The society and the government also need to keep objective and inclusive, increase talent reserve and industry support, maintain active supervision, promote the establishment of relevant laws and regulations, and maintain a good industry ecology.

A simple mathematical method to identify optimal biplane fluoroscopic angulations for chronic total occlusion percutaneous coronary intervention using CT angiography.

The concept of three-dimensional (3D) wiring for chronic total occlusion (CTO) percutaneous coronary intervention (PCI) is now widely accepted among coronary interventionalists. The 3 axes, i.e., the 2 X-ray beams and the CTO segment, should intersect with each other at as close to a right angle as possible. However, how to specify optimal fluoroscopic angulations for a given CTO segment has not been well established. We aimed to develop a simple and practical method to identify optimal fluoroscopic angulations for CTO PCI. A CTO vector can be derived from slab maximum intensity projection (MIP) images of coronary computed tomography (CT) angiography. Using trigonometric functions, the inner product of vectors and the equation of a plane, we calculated 2 fluoroscopic vectors perpendicular to each other and to the CTO vector. We applied this method to a patient with mid-left circumflex CTO and translated the resulting fluoroscopic vectors into optimal fluoroscopic angulations. To facilitate its use, we developed a calculator using spreadsheet software that can output optimal fluoroscopic angulations within a practical range by inputting the x, y, and z components of the CTO vector. This approach also helps to minimise dead angles in biplane fluoroscopy. This method has the potential to make CTO PCI safer and easier, without requiring dedicated equipment or software. Its effectiveness should be validated in clinical practice.

Adaptive Techniques for the Online Estimation of Spatial Fields With Mobile Sensors

The regression-based reconstruction of spatial fields by static sensors requires the number of measurements be at least equal to the number of unknown parameters in order to provide a unique solution. Improvements include the use of mobile sensor networks to arrive at higher accuracy estimates. An alternate approach utilizes adaptive techniques to update the parameter estimates online. Such adaptive techniques need persistence of excitation to ensure convergence of the parameter and function estimates. It is shown that the motion of just a single sensor is a necessary condition for persistence of excitation and, subsequently, of function convergence. Having a prescribed sensor guidance is also a sufficient condition for function convergence. First, a Lyapunov-based adaptation and guidance is presented and it is shown that persistence of excitation necessitates the time dependence of the outer product of the regressor vector with itself and which in turn requires the motion of the sensor within the spatial domain. Subsequently, a gradient-based adaptive scheme relaxes the Lyapunov-based sensor guidance to any user-defined guidance as long as the outer product of the associated rank-one regressor vector with itself has a uniformly positive definite integral. The latter adaptation is conducive to the inclusion of platform dynamics resulting in a vehicle control design needed to attain parameter convergence. Extension of the centralized solution to distributed estimation using a network of mobile sensors is also examined. These results are demonstrated with simulations in one and two dimensions.