Method Calculations Research Articles

Absorption spectra of the purple nonsulfur bacteria light-harvesting complex: A DFT study of the B800 part

We’ve studied the B800 part of Rhodoblastus acidophilus light-harvesting complex (LH2) by several quantum chemical techniques based on the density functional theory (DFT) and determined the specific method and a minimal reliable model suitable for further studies of the LH2. In addition to bacteriochlorophyll a molecules, the minimal model includes two α and one β chain amino acids. Within the model, we are able to reproduce the contribution of the B800 ring of nine bacteriochlorophyll a molecules to the near infrared Qy absorption band. We also discuss the use of hybrid DFT calculations for precise energy and optical estimations and DFT-based tight binding (DFTB) method for the large-scale calculations. Crucial importance of Hartree-Fock exchange interaction for the correct description of B800 peak position was shown.

Numerical investigation on the wake and energy dissipation of tidal stream turbine with modified actuator line method

This study evaluates correction methods for the actuator line method in tidal stream turbine calculations. Findings indicate that three-dimensional Gaussian distribution coefficients align closely with experimental results when ε = 2dr. Tip loss correction addresses abnormal axial force coefficient elevation at the blade tip, while stall delay correction minimally impacts standard turbine operation. Root loss correction slightly affects the root vortex but notably delays the disappearance of the nacelle after tail flow's bimodal region to 4D, contrary to observations. Using a cylinder correction at the blade root improves the root vortex representation. Enhanced ALM, combined with LES, simulates wake and energy loss across varying turbulence intensities. At low turbulence, the spiral vortex structure is clearer, with fewer stray vortices and a more regular circular shape. Increasing turbulence blurs the structure, introducing more turbulent vortices and losing regularity. Entropy production concept represents energy losses as total, direct, and turbulence entropy production. Direct entropy production is minimal, localized at blade tip, nacelle, and support structures due to significant velocity gradients. Indirect entropy production causes substantial energy loss, resembling wake flow's vortex pattern due to turbulent pulsation. With higher turbulence, EPR, EPDD, and EPTD decline as wake vortices are disrupted, reducing energy loss.

RITZ METHOD IN THE DISCRETE APPROXIMATION OF DISPLACEMENTS FOR SLAB CALCULATION

Introduction: The FEM reduces the problem of structural analysis for various building structures to the formation and solution of a system of linear algebraic equations. For this purpose, there are techniques available for obtaining FE stiffness and flexibility matrices where the main structural deformation characteristics are taken into account. However, the FEM can also be considered as a special case of the Ritz method in the discrete approximation of the required functions. In the functional of full potential deformation energy with regard to the considered structure, all adopted stress-strain state characteristics are taken into account. Since it is difficult or impossible to find continuous approximation functions both in the classic version of the Ritz method and in the Bubnov–Galerkin method for some types of edge restraint in such building structures as beams, slabs, or shells, it is possible to use the Ritz method in the discrete approximation of the required functions (by analogy with the FEM). This paper presents a method of such calculations using slab calculations as an example. It is shown that, due to introducing some notations (operators), the process of finding the coefficients of the system of linear algebraic equations creates no difficulties and is easily programmable. The proposed method is not an alternative to the FEM, which is the most effective numerical method for the calculation of complex three-dimensional building structures. Purpose of the study: We aimed to create a method for calculating slabs by the Ritz method in the discrete approximation of the deflection function for edge restraint cases when it is difficult or impossible to find continuous approximation functions in the classic version of the Ritz method and the Bubnov–Galerkin method. Methods: Based on the application of the Ritz variational method in the discrete approximation of displacements for slab calculation, all the basic relations for rectangular finite elements with 12 degrees of freedom are obtained, and an algorithm for forming the coefficients of the system of linear algebraic equations is developed. Results: For the first time, the solution by the Ritz method in the discrete approximation of slab displacements is obtained for the case when two edges of the slab are rigidly restrained and other two edges are free. In this case, the correct solution of the above problem is possible only with the use of the proposed method and FEM. For the test problem, we performed a comparison of the results of the calculation using the proposed method with the results using the classic Ritz method, which showed their very close agreement. The accuracy of the obtained results was assessed.

THE POTENTIAL FOR ENSURING FOOD SECURITY IN UKRAINE IN THE CONTEXT OF THE ONGOING MILITARY CONFLICT

The subject of the research is the study of Ukraine's food security and the potential for improving it. Methodology. The article uses general scientific and specific methods of economic research: the method of content analysis (when processing scientific sources and reviewing the thematic literature, deduction and induction); abstract and logical method (when identifying problematic aspects of ensuring the country's food security, substantiating conclusions and proposals); the method of statistical calculations of regression economics (when substantiating the economic and mathematical model of food security, calculating the indicator of the actual state of self-sufficiency in food security). The purpose of the study is to assess the level of food security achieved by Ukraine and to identify the main factors that affect the potential for its possible improvement. Conclusion. Ukraine has significant potential to ensure food security at the national and European levels. However, over the past two years, Ukraine has lost its position in the global food security ranking according to the GFSI. The main problematic aspects that led to this are as follows: irrational use of land and labour resources, aging and migration of the rural population; sharp loss of agricultural biodiversity; high level of chemicalisation of agricultural production; loss of the potential for quality reproduction of agricultural land; significant inclusive gaps within rural areas; low level of funding for agricultural science and a predominantly raw material, agrarian orientation. The main reason for the downgrade of Ukraine's GFSI rating in 2022 was the ongoing military operations in the country. Despite the existing problematic aspects, the Ukrainian agricultural sector showed the highest level of sustainable development compared to other types of economic activity. The share of profitable enterprises in the sector was 79%. Ukraine is currently self-sufficient in food security for almost all types of agricultural products. The constructed economic-mathematical model showed a high degree of dependence of food security on such factors as the total value of assets of agricultural formations, the value of fixed assets and the amount of profit. It was determined that the key condition for increasing the potential for ensuring food security in Ukraine, both at the national and European level, should be the social responsibility of agribusiness and raising the level of sustainable development of agriculture and rural areas.

Adiabatic connection interaction strength interpolation method made accurate for the uniform electron gas.

The adiabatic connection interaction strength interpolation (ISI)-like method provides a high-level expression for the correlation energy, being, in principle, exact not only in the weak-interaction limit, where it recovers the second-order Görling-Levy perturbation term, but also in the strong-interaction limit that is described by the strictly correlated electron approach. In this work, we construct a genISI functional made accurate for the uniform electron gas, a solid-state physics paradigm that is a very difficult test for ISI-like correlation functionals. We assess the genISI functional for various jellium spheres with the number of electrons Z ≤ 912 and for the non-relativistic noble atoms with Z ≤ 290. For the jellium clusters, the genISI is remarkably accurate, while for the noble atoms, it shows a good performance, similar to other ISI-like methods. Then, the genISI functional can open the path using the ISI-like method in solid-state calculations.

MULTIMODALITY AND NEUROCOPYWRITING AS DIGITAL COMMERCIAL NARRATIVE STRATEGIES

The article discusses the strategies and tactics of the commercial narrative, which enable a pragmatic influence on the cognitive, emotional, and volitional sphere of the addressee-potential consumer. In a commercial narrative, verbal and non-verbal components form one visual, structural, meaningful, and functional whole. The purpose of our research is to analyze the techniques and tactics of implementing multimodality and neurocopywriting strategies in the English-language digital commercial narrative. In accordance with the set goal, the tasks of the article are: - Present the types of commercial narrative; - Determine the main tactics of neurocopywriting and multimodality in sales texts in the conditions of digital commerce transformation; - Analyze lingual and paralingual means of implementing commercial narrative tactics. We consider the commercial narrative as a combination of modes in the stereoscopy of semiotic and cognitive approaches. The development of Svitlana Zhabotynska was chosen as an appropriate methodology for the analysis of multimodality, and the definition of storytelling tactics is based on the main positions of David Herman. The elements of the method of quantitative calculations made it possible to generalize the obtained results. The success of the commercial narrative in its two types (branding and sales storytelling) is achieved through the interaction of different modes of sensorics, which change states of consciousness and participate in the receiver’s decision-making. The simultaneous combination of the codes of different sign systems to construct the recipient’s emotions and decisions is the essence of the multimodality strategy in the commercial narrative. The article analyzes the tactics of creating a commercial narrative with a certain construction of meaning through the interference of a complex of lingual and paralingual means. The cognitive dominance of the commercial narrative (conveying familiar information in an unusual way or from a new perspective, focusing on the advantages of the object of the offer: “Elaboration, Extending, Questioning, Combining” according to S. Zhabotynska) should cause a certain emotional reaction (surprise, expectation, trust) in the consumer, constructing a certain image. The purpose of creating such an image is to set the consumer in a positive mood and create motivational incentives. It is for the purpose of stimulating neurotransmitters that there is a need for the design of sales storytelling using specific linguistic means: allusions, emotionally-tinged vocabulary, unusual combinations of words, various resources of intertextuality that stimulate sensory sensations, and, in turn, is the task of the neurocopywriting strategy in commercial narrative. Table Landscape of responses made it possible to determine the digital reputation of the commercial narrative (concentration of meanings, general awareness, and recognition (authority), and the analysis of sales reports on the official companies’ websites and reviews in social networks visualized the result of the audit of the success of the commercial narrative. The study of the pragmatics of multimodality strategies and neurocopywriting in the modern digital space of commercial communication is an actual and promising research field in linguistics.

CORRECTION OF THE CYLINDRICAL HELICAL-GEAR WHEEL PAIR FOR WEAR DECREASE OF TEETH’ INVOLUTE SURFACES

Purpose. It is to create a method for determination of profile shift coefficients, such that during the operation of a cylindrical helical-gear pair the sum of the wear rates of involute surfaces on the contacting sections at the highest and lowest active points of teeth’ profiles of driving and driven wheels will be a minimum.
 Research methods are based on integrated application of the involute gear theory and tribological laws. The secant method that is known in computational mathematics is used to find a root of nonlinear equation.
 Results. The method is created for determination of rational values of correction parameters for cylindrical helical-gear wheels, which maximize the service life of this gear pair until the maximum sum of worn-layer thicknesses on the contacting sections of the teeth’ active surfaces reaches limiting permissible value. An example of application of this method in design calculation of the cylindrical helical-gear pair is given.
 Scientific novelty. Calculation model is elaborated for determination of the sum of worn-layer thicknesses on the most wearing contacting sections of the teeth’ active surfaces of a cylindrical helical-gear wheel pair. It is derived an equation of the linkage between such values of profile shift coefficients for the driving and driven helical-gear wheels which minimize the greatest sum of wear rates on mentioned sections of teeth’ surfaces. Solution of this equation by numerical method for the helical-gear pair having standard distance between axes allows determination of rational values of correction parameters for these wheels.
 Practical value. Application of the created method for determination of profile shift coefficients is expedient in design of cylindrical helical-gear pairs for machines and equipment, which operate in conditions when it is impossible to protect the engagement region from ingress of abrasive particles.

A cutoff-based method with charge-distribution-data driven pair potentials for efficiently estimating electrostatic interactions in molecular systems.

We introduce a simple cutoff-based method for precise electrostatic energy calculations in the molecular dynamics (MD) simulations of point-particle systems. Our method employs a theoretically derived smooth pair potential function to define electrostatic energy, offering stability and computational efficiency in MD simulations. Instead of imposing specific physical conditions, such as dielectric environments or charge neutrality, we focus on the relationship represented by a single summation formula of charge-weighted pair potentials. This approach allows an accurate energy approximation for each particle, enabling a straightforward error analysis. The resulting particle-dependent pair potential captures the charge distribution information, making it suitable for heterogeneous systems and ensuring an enhanced accuracy through distant information inclusion. Numerical investigations of the Madelung constants of crystalline systems validate the method's accuracy.

Comparison between Calculated, Simulated and Actual Plant Data of Multiple Effect Evaporators to Concentrate Sugarcane Juice

Multiple effect evaporators systems operating at steady state can be described by a series of nonlinear algebraic equations that include total and solute mass balances, energy balances, heat transfer rate equations, and the composition and temperature dependence of related thermodynamic properties such as vapor pressures and enthalpies. The main objective is to compare between the manual calculations, simulation and real data collected from Asalaya plant for validation the best design of multiple effect evaporators system in forward feed used in Asalaya Sugar Factory. In this design a short tube vertical evaporator, Calandria type has been used. The models include overall equations of materials balance, equations of energy balance and equations of heat transfer rate for measurement area for all the effects. These equations were solved using manual calculations methods and MATLAB coded program. The results of the present investigations have been compared with the data obtained from the Asalaya Sugar Factory with five evaporators. The results showed that the concentration of sugar cane juice at the final stage is equal to 60 Brix for the manual calculations, simulation and actual plant data with zero error. The temperature of solution in the pre- effect evaporator was found to be about (114.94, 114.94, 115)ºC, with a relative error equal to 0.05% and the steam temperature in the pre effect was found about (120)ºC for the manual calculations, simulation and actual plant data, with zero error. The area and number of tubes in the (pre, second, third and fourth) effect, are in a good agreement, with the standard value (Er=3.26%). The above results show great similarity with the real behavior of evaporator unit. This can be used as a reliable tool\for the simulation of different operating conditions.

Predicting the FCI Energy of Large Systems to Chemical Accuracy from Restricted Active Space Density Matrix Renormalization Group Calculations.

We theoretically derive and validate with large scale simulations a remarkably accurate power law scaling of errors for the restricted active space density matrix renormalization group (DMRG-RAS) method [J. Phys. Chem. A 126, 9709] in electronic structure calculations. This yields a new extrapolation method, DMRG-RAS-X, which reaches chemical accuracy for strongly correlated systems such as the chromium dimer, dicarbon up to a large cc-pVQZ basis and even a large chemical complex such as the FeMoco with significantly lower computational demands than those of previous methods. The method is free of empirical parameters, performed robustly and reliably in all examples we tested, and has the potential to become a vital alternative method for electronic structure calculations in quantum chemistry and more generally for the computation of strong correlations in nuclear and condensed matter physics.

High-order finite element method for atomic structure calculations

We introduce featom, an open source code that implements a high-order finite element solver for the radial Schrödinger, Dirac, and Kohn-Sham equations. The formulation accommodates various mesh types, such as uniform or exponential, and the convergence can be systematically controlled by increasing the number and/or polynomial order of the finite element basis functions. The Dirac equation is solved using a squared Hamiltonian approach to eliminate spurious states. To address the slow convergence of the κ=±1 states due to divergent derivatives at the origin, we incorporate known asymptotic forms into the solutions. We achieve a high level of accuracy (10−8 Hartree) for total energies and eigenvalues of heavy atoms such as uranium in both Schrödinger and Dirac Kohn-Sham solutions. We provide detailed convergence studies and computational parameters required to attain commonly required accuracies. Finally, we compare our results with known analytic results as well as the results of other methods. In particular, we calculate benchmark results for atomic numbers (Z) from 1 to 92, verifying current benchmarks. We demonstrate significant speedup compared to the state-of-the-art shooting solver dftatom. An efficient, modular Fortran 2008 implementation, is provided under an open source, permissive license, including examples and tests, wherein particular emphasis is placed on the independence (no global variables), reusability, and generality of the individual routines. Program summaryProgram Title: featomCPC Library link to program files:https://doi.org/10.17632/962fzmm7f7.1Licensing provisions: MITProgramming language: Fortran with command-line interfacesNature of problem: Solution of the Schrödinger, Dirac, and Kohn–Sham equations of density functional theory for isolated atoms.Solution method: A high-order finite element method is used to assemble a generalized eigenproblem that is then solved for eigenvalues and orbitals. The Poisson equation is solved using the finite element method also. Self-consistent field equations are solved using Pulay mixing.Additional comments including restrictions and unusual features: Our solution methodology for the Dirac equation does not suffer from spurious states. We maintain high accuracy even for κ=±1 states. Unlike other methods, our approach is not limited to Coulombic or self-consistent potentials and can handle non-uniform meshes, including exponential meshes.Restrictions: Spherical symmetry.

Membrane transport of polyfunctional alkyl (N-alkyl-N,N-dioctylammoniomethyl)phosphonates

The membrane transport properties of phosphorylated betaines in relation to mono- and polyfunctional carboxylic acids were studied. The structure of transferred H-complexes was discussed; using IR spectroscopy, the main coordination centers of carriers were revealed. Using the method of quantum chemical calculations, the relationship between the amount of substrate flux, their lipophilicity and the structure of the resulting H-complexes was shown.

Influence of Markowitz Method Risk and Return Calculations as a Basis for Investment Decisions in BEI BUMN Shares 20 Period 2019-2022

The aim of writing this scientific article is to determine the influence of the Markowitz Method of risk and return calculations on Investor Rationality for the Security of Investing in 20 BUMN IDX Shares for the 2019-2022 Period. The method used in this research is a descriptive method with a quantitative approach. The type of data used is secondary data which takes data from the official website idx.com and also investing.com. The sample used was 20 state-owned companies. The data collection technique in this research is by using documentation techniques. The data collection process consists of: calculating the expected return for each company, conducting statistical tests using SPSS 24, and finally conclusions. The results of this research are that the Markowitz method of calculating risk & return has a significant effect on investors' rationality in investing in BUMN 20 shares.

2D antiscatter grid and scatter sampling based CBCT method for online dose calculations during CBCT guided radiation therapy of pelvis.

Online dose calculations before the delivery of radiation treatments have applications in dose delivery verification, online adaptation of treatment plans, and simulation-free treatment planning. While dose calculations by directly utilizing CBCT images are desired, dosimetric accuracy can be compromised due to relatively lower HU accuracy in CBCT images. In this work, we propose a novel CBCT imaging pipeline to enhance the accuracy of CBCT-based dose calculations in the pelvis region. Our approach aims to improve the HU accuracy in CBCT images, thereby improving the overall accuracy of CBCT-based dose calculations prior to radiation treatment delivery. An in-house developed quantitative CBCT pipeline was implemented to address the CBCT raw data contamination problem. The pipeline combines algorithmic data correction strategies and 2D antiscatter grid-based scatter rejection to achieve high CT number accuracy. To evaluate the effect of the quantitative CBCT pipeline on CBCT-based dose calculations, phantoms mimicking pelvis anatomy were scanned using a linac-mounted CBCT system, and a gold standard multidetector CT used for treatment planning (pCT). A total of 20 intensity-modulated treatment plans were generated for five targets, using 6 and 10 MV flattening filter-free beams, and utilizing small and large pelvis phantom images. For each treatment plan, four different dose calculations were performed using pCT images and three CBCT imaging configurations: quantitative CBCT, clinical CBCT protocol, and a high-performance 1D antiscatter grid (1D ASG). Subsequently, dosimetric accuracy was evaluated for both targets and organs at risk as a function of patient size, target location, beam energy, and CBCT imaging configuration. When compared to the gold-standard pCT, dosimetric errors in quantitative CBCT-based dose calculations were not significant across all phantom sizes, beam energies, and treatment sites. The largest error observed was 0.6% among all dose volume histogram metrics and evaluated dose calculations. In contrast, dosimetric errors reached up to 7% and 97% in clinical CBCT and high-performance ASG CBCT-based treatment plans, respectively. The largest dosimetric errors were observed in bony targets in the large phantom treated with 6 MV beams. The trends of dosimetric errors in organs at risk were similar to those observed in the targets. The proposed quantitative CBCT pipeline has the potential to provide comparable dose calculation accuracy to the gold-standard planning CT in photon radiation therapy for the abdomen and pelvis. These robust dose calculations could eliminate the need for density overrides in CBCT images and enable direct utilization of CBCT images for dose delivery monitoring or online treatment plan adaptations before the delivery of radiation treatments.

An Application of a Higher Computational Efficiency Method in Thermo-Hydraulic Calculations of First Wall in Fusion Blanket

An Application of a Higher Computational Efficiency Method in Thermo-Hydraulic Calculations of First Wall in Fusion Blanket

Self-Rotation of Electrothermally Responsive Liquid Crystal Elastomer-Based Turntable in Steady-State Circuits.

Self-excited motions, characterized by their ability to harness energy from a consistent environment and self-regulate, exhibit significant potential in micro-devices, autonomous robotics, sensor technology, and energy generation. This study introduces an innovative turntable system based on an electrothermally responsive liquid crystal elastomer (LCE). This system facilitates self-rotation within a steady-state circuit. Employing an electrothermal LCE model, we have modeled and numerically analyzed the nonlinear dynamics of an LCE-rope within steady-state circuits, utilizing the four-order Runge-Kutta method for calculations. The numerical results reveal the emergence of two distinct motion patterns in the turntable system under steady-state conditions: a self-rotation pattern and a static pattern. The self-rotation is initiated when the system's absorbed energy surpasses the energy lost due to damping effects. Furthermore, this paper delves into the critical conditions necessary for initiating self-rotation and examines the influence of various key dimensionless parameters on the system's rotation amplitude and frequency. These parameters include gravitational acceleration, the initial position of the mass ball, elastic stiffness of the LCE and spring, limiting temperature, heating zone angle, thermal shrinkage coefficient, and damping factor. Our computational findings establish that these parameters exert a modulatory impact on the rotation amplitude and period. This research enhances the understanding of self-excited motions and offers promising avenues for applications in energy harvesting, monitoring, soft robotics, medical devices, and micro- and nano-devices.

Penerapan Metode Evaluation based on Distance from Average Solution (EDAS) dalam Optimalisasi Layanan dan Pemasaran Coffeeshop

Business owners of coffee shops that fall under the Micro, Small, and Medium Enterprises (MSMEs) employ marketing methods to attract more clients to satisfy the demands and preferences of coffee enthusiasts. However, consumer purchasing behavior demonstrates the difficulty in evaluating marketing performance. In light of this, this study employs the Distance from Average Solution Evaluation Method (EDAS). Meanwhile, coffee shop business brands observed and used as alternatives in this study are Coffee Tanem, 1915 Koffie-Huis, Friends of Coffee Salatiga, Dusk Koffie Salatiga, and Street Side Coffee Salatiga. The results of this study show that the EDAS method can be used to optimize coffee shop business services and marketing as a strategic step in strengthening and improving the performance of the coffee shop business or business. In the context of testing the EDAS decision model, each alternative is assigned a random code (A1-A5). Coffee varieties (C1), aroma and roasted level (C2), serving technique variants (C3), beverage prices (C4), and coffeeshop locations (C5) are often employed as criteria, with categories C1–C3 representing advantages, and C4–C5 representing expenses. Based on the EDAS method's calculation results, it can be seen that the top-ranking coffee shops are those that offer a variety of coffee bean varieties (robusta and arabica), various aromas, and roasted levels (light, medium, dark), various serving methods using espresso machines and manual brew, affordable drink prices, and strategically located coffee shops with enough parking. Thus, it is advised that coffee shop business experts assist in improving capital capabilities and business performance and optimize marketing mix components in STP (Segmenting, Targeting, Positioning) marketing strategies to increase trust, sales volume, consumer satisfaction, and loyalty.

Sensitivity Analysis of Transient Forced Response of Mistuned Bladed Disks Under Complex Excitation and Varying Rotation Speed

Abstract During accelerations and decelerations of gas-turbine engines, the transient vibration effects in bladed disk vibration become significant and the transient response needs to be efficiently and accurately assessed. This paper develops an effective method for efficient calculations of the sensitivity of the transient vibration response for a mistuned-bladed disk under varying rotation speeds. The sensitivities are calculated concerning two major factors: (i) the blade mistuning and (ii) the rotor acceleration/deceleration rates. The method uses the large-scale finite element modeling of the bladed disk to accurately describe the dynamic properties of the mistuned bladed disk. The method can be applied for a case when the loading is the transient load, with the amplitude and frequency spectrum changing with rotation speed. The dependency of the modal characteristics on the rotation speed is included in the formulation of the sensitivity analysis method. Efficient reduced order models are used to reduce the computational cost, which can adapt to the effects of the varying rotation speed on the natural frequencies and mode shapes of the mistuned bladed disk under transient conditions. The expressions for the sensitivities are derived analytically which provides high accuracy and speed of the calculations. The method has been implemented in a computer code and thoroughly verified using a set of test cases. The studies of transient forced response sensitivity have been performed for realistic bladed disk models.

Applicable predictive factors extracted from peak flow trajectory for the prediction of asthma exacerbation

BackgroundReal-time asthma exacerbation prediction and acute asthma attack detection are essential for patients with severe asthma. Peak expiratory flow (PEF) exhibits a potential for use in long-term asthma self-monitoring. However, the method for processing PEF calculations remains to be clarified. ObjectiveTo develop clinically applicable novel exacerbation predictors calculated using PEF records. MethodsPreviously proposed exacerbation predictors, including the slope of PEF, percentage predicted PEF, percentage best PEF, the highest PEF over the lowest PEF within specific periods, and PEF coefficient of variation, in addition to a novel indicator delta PEF moving average (ΔMA), defined as the difference between 14-day and 3-day average PEF values, along with moving average (MA) adjusted for PEF reference (%ΔMA), were verified using the Hokkaido-based Investigative Cohort Analysis for Refractory Asthma data of 127 patients with severe asthma from whom 73,503 PEF observations were obtained. Receiver operating characteristic curves for all predictors were drawn, and the corresponding areas under the curve (AUCs) were computed. Regression analysis for MA and percentage MA were conducted. ResultsThe most outstanding performance was shown by ΔMA and %ΔMA, with AUC values of 0.659 and 0.665 in the univariate model, respectively. When multivariate models were incorporated with random intercepts for individual participants, the AUC for ΔMA and %ΔMA increased to 0.907 and 0.919, respectively. ConclusionThe MA and percentage MA are valuable indicators that should be considered when deriving predictors from the PEF trajectory for monitoring exacerbations in patients with severe asthma. Trial RegistrationThe Hokkaido-based Investigative Cohort Analysis for Refractory Asthma was registered in the University Hospital Medical Information Network Clinical Trials Registry (UMIN ID: 000003254). https://center6.umin.ac.jp/cgi-open-bin/ctr_e/ctr_view.cgi?recptno=R000003917

SmartAgro-Spectral: Teknik Pengukuran Kandungan Nitrit Pada Sarang Burung Walet Berbasis Spektral Menggunakan Metode Regresi Linier

Indonesia is the largest exporter of edible bird’s nest (EBN) to China, involving many EBN farmers from various regions in Indonesia. Therefore, a portable device is needed to rapidly and accurately measure the required quality of SBW to avoid rejection by Chinese buyers, which could result in significant losses. Consequently, for this purpose, an electronic instrument has been developed. smartAgro-Spectral is a microcontroller-based electronic instrument that measures nitrite content in edible bird’s nest (EBN) using linear regression method in machine learning calculations. This instrument can measure nitrite content based on the intensity of colors produced by EBN products. The coloring process is carried out by mixing EBW powder with Sulphanilamide solution and N-(1-naphthyl) Ethylenediamine Dihydrochloride (NED) solution. The concentration of EBN solution is normalized to values between 0.2 ppm and 0.7 ppm. The measurement process is carried out by emitting 18 waves of the light spectrum. The intensity of the 18 wavelengths of the measured light spectrum was selected based on the strong correlation between the intensity of the light spectrum and the value of nitrite content in the EBN product. The measurement results show that the intensity of the light spectrum that has a strong linear correlation is at wavelengths of 460 nm, 485 nm, 510 nm, 535 nm, and 610 nm. So, smartAgro-Spectral electronic instruments can be realized based on the intensity relationship of each wavelength through multiple linear regression analysis, and are able to linearly measure nitrite content in EBW products with a precision level of 99.85% and an accuracy rate of 99.85%.