Variable Component Research Articles

Изучение отображения вибрационных возмущений в геометрии формируемой резанием поверхности при точении

Introduction. The development of virtual digital models of the machining process on metal-cutting machines is a dynamically developing direction of increasing the efficiency of machine-building production. Such models include subsystems of parts quality prediction. Accuracy and validity of its work directly depends on the built model of dynamic cutting system, which is perturbed by force noise, the sources of which have different physical origin. In addition, the autonomous dynamic system itself is a generator of various attracting sets of deformations, such as limit cycles or chaotic attractors. Taking into account various nonlinear transformations in the properties of the dynamics of the cutting process allows increasing the adequacy of the model to the real process and is an actual task in the construction of simulation modeling systems of the dynamics of surface machining by cutting. Study object. Our earlier studies allow us to determine the geometry corresponding to the deformation trajectories of the surface formed by cutting. However, the adequacy of the mapping of the calculated trajectories to the geometry estimates remains not quite clear. The proposed paper focuses on achieving an adequate mapping of calculated as well as measured strain trajectories into the geometric topology of the part. The aim of the work is to evaluate the mapping of vibration perturbations of the system into the geometry of the surface formed by cutting. Method and methodology. The research is of experimental-theoretical nature. The content of the research includes the study of the correspondence of frequency characteristics obtained on the model and in real machining. The main attention is paid to the mapping of deformations to the part geometry. For this purpose, the paper considers the coherence functions between the strain functions and the part profile. Results and Discussion. It is shown that the conditioning of these transformations has a limited frequency range in which the explanation of the variable components of the generated relief is statistically significant. Mathematical modeling of the dynamic cutting system based on the mechanics of interaction between tool and workpiece allows adequate prediction of the macro geometry of the part formed by cutting. The obtained mathematical tools can be used to create systems for predicting the geometry of the machined surface.

A novel generalized Vold-Kalman filtering for wind turbine fault diagnosis

Fault diagnosis of offshore wind turbines (WTs) is vital to the reliability and efficiency of wind power generation. Generalized demodulation has been demonstrated to be effective in revealing the fault-related frequencies, but there are intricate interfering components in the demodulation spectra due to the iterative demodulation operation and the complex modulation nature of vibration signals of WT. This paper develops a novel generalized Vold-Kalman filtering approach. To separate the signal components, Vold-Kalman filter is adopted to the amplitude envelope of vibration signal by exploiting its merit in non-component decomposition, in which a frequency set is constructed by the modulation nature of machinery vibration. The phase functions of the frequencies in the frequency set are constructed, by which the variable components are transformed into constant ones. The proposed method is tested via the data of rolling bearings and a WT planetary gearbox.

Fighting Biofilm Bearing Microbes, Global Challenges, Initiatives and Current Novel Therapeutics/Antibiofilm Strategies: A Narrative Scientific Record

Microbial survival against diverse anti-biocidal agents has advance beyond single organism interaction into intricate sessile cells consisting dynamic three-dimensional extracellular complex matrix of water channels. Such complex architecture is built with heterogeneous and variable components that encourage failure of antimicrobial-chemotherapeutic strides especially among biofilm bearing/expressing microbes (BBM). This is a noteworthy public health concern as such occurrence has welcomed global attention in recent times with focus on fighting BBM as well as exploration of novel therapeutic strategies. A narrative scientific description of biofilm as a community of microbes wrapped in extracellular polymeric substances (EPS) was reviewed. The challenges on disease/infection recalcitrance, risk to public health and the necessity to develop novel therapeutics for the management/control and suppression of biofilm linked infections were emphasized. It also summarized potential approaches including the use of antibiofilm/anti-adhesion agents, antimicrobial proteins (AMPs), aptamers, Nano-Particulates (NPs), quorum sensing inhibitors (QSIs), and peptide or protein-based nucleic acids (PNAs) while discussing the agents efficient potential ability. Such anti-biofilm agents/mechanisms and their target-specific-therapeutic relevance promises future for the management/control of biofilm associated microbial infections. Its application may also herald a generational effective combination therapy against illnesses/infections caused by BBM and served as a potential source for BBM global control.

Chronic inhibition of angiotensin converting enzyme lowers blood pressure in spontaneously hypertensive rats by attenuation of sympathetic tone: The role of enhanced baroreflex sensitivity

Spontaneously hypertensive rats (SHR) are characterized by sympathetic hyperactivity and insufficient parasympathetic activity, and their high blood pressure (BP) can be lowered by long-term inhibition of the renin-angiotensin system. The aim of our study was to determine the influence of chronic inhibition of angiotensin converting enzyme (ACE) by captopril on cardiovascular regulation by the sympathetic and parasympathetic nervous system. Implanted radiotelemetric probes or arterial cannulas were used to measure mean arterial pressure (MAP), heart rate (HR), and arterial baroreflex in adult SHR and Wistar-Kyoto (WKY) rats under basal or stress conditions. MAP and the low-frequency component of systolic blood pressure variability (LF-SBPV, marker of sympathetic activity) were greater in SHR than in WKY rats. Under basal conditions chronic captopril treatment reduced both parameters more effectively in SHR, and the same was true during acute restraint stress. HR was similar in control rats of both strains, but WKY rats showed greater heart rate variability (HRV), indicating higher parasympathetic activity. Captopril administration increased HR in both strains, whereas HRV was decreased only in WKY. Chronic captopril treatment improved the impaired baroreflex-HR control in SHR by increasing the sensitivity but not the capacity of vagal arm of arterial baroreflex. Captopril treatment attenuated BP changes elicited by dimethylphenylpiperazinium (DMPP, agonist of nicotinic acetylcholine receptors), especially in SHR, indicating that sympathetic nerve transmission is facilitated by angiotensin II more in hypertensive than in normotensive animals. Thus, chronic ACE inhibition improves baroreflex sensitivity and lowers BP through both central and peripheral attenuation of sympathetic tone.

PROBLEMS OF PROFESSIONAL TRAINING OF FUTURE EDUCATORS FOR THE DEVELOPMENT OF THE CREATIVE POTENTIAL OF CHILDREN IN THE CONDITIONS OF AN INCLUSIVE EDUCATIONAL ENVIRONMENT

The article raises the issue of professional training of future educators for the development of children's creative potential in the conditions of an inclusive educational environment. The key object of the educational process in the modern educational paradigm is the personality of the child, who is able to critically perceive reality, analyse, propose ideas for solving tasks, realize his/her own uniqueness, the need for the development of individual abilities. The development of creative potential of a preschool child is aimed at forming the foundation for revealing the potential of each child in accordance with his needs, abilities, etc. The problem of the development of children's creative potential is intensified by the integration of inclusive education into the educational space of regular preschool education institutions, which puts forward new requirements for the professional training of educators who ensure the comprehensive development of all children in a single inclusive educational environment, adaptation and socialization of children with special educational needs in interaction with peers. Based on the analysis of scientific, pedagogical and methodological literature, the author highlights contemporary problems related to the research topic: the integration of inclusive education in Ukraine continues and has both positive developments and unresolved problems at the state and regional levels that slow down the achievement of the goal; the involvement of children with special educational needs in regular preschool education institutions requires in-depth improvement in order to expand opportunities for all children; lack of a model for the development of children's creative potential under the conditions of an inclusive educational environment; insufficient number of necessary specialists to work in the conditions of an inclusive educational environment; the need to modernize the variable component of professional training of future educators. The author comes to the conclusion that solving the above-mentioned problems requires targeted, thorough and long-term practical research in order to improve the quality of education, the productive development of the creative potential of each child in the conditions of an inclusive educational environment.

<i>There’s Less Jakan’je Here</i> (Unstressed Vowel Systems of Two Neighbouring Tambov Dialects)

The paper deals with the unstressed vowels systems after palatalized consonants in two neighbouring Southern Russian dialects from Staroyuryev district, Tambov region (Ryazan’ group). The results obtained show that 1) the two dialects located at a distance of 5 kilometers from each other are characterized by different types of the assimilative-dissimilative jakan’je: novoselkovsky and orekhovsky; 2) there are no distinctions in this regard in male in female idiolects; 3) dialectal speakers are quite aware of those subtle differences in their speech. Meanwhile, the obtained data lead us to the conclusion that there exists a gradual transitional distinction among various “types” of assimilative-dissimilative jakan’je in South-Eastern Russian dialects rather than a strict categorial (“phonological”) boundary between them since the dialects in question show a gradual transition from prestressed [i] to [a] after palatalized consonants before stressed mid-open and mid-close vowels while there is no variability detected in the position before low and high vowels. Thus, in the system of unstressed vocalism there are both completely stable and variable components.

The entrainment of action potential duration and contraction amplitude by recapitulation of respiratory sinus arrhythmia in isolated cardiac myocytes

Abstract Introduction Respiratory sinus arrhythmia (RSA) is the oscillation of heart rate in phase with ventilation and represents the high frequency component of heart rate variability. RSA is prevalent in the young and the endurance-trained and its loss is considered a prognostic indicator for sudden cardiac death. The recapitulation of RSA improves cardiac function in animal models of heart failure1,2. However, the precise mechanisms by which RSA affects cardiac function are unknown. Hypothesis: We examined the hypothesis that the recapitulation of RSA in isolated ventricular myocytes affects the stimulus interval-dependence of action potential duration (APD) and sarcomere shortening through mechanisms involving sarcoplasmic reticulum (SR) Ca2+ release. Methods Hearts were excised from adult male guinea pigs under general anaesthesia (140 mg/kg bodyweight euthatal, i.p.) and left ventricular myocytes isolated. Isolated myocytes were superfused with Tyrode’s solution for perforated patch whole-cell current clamp recording and action potentials and sarcomere length measured simultaneously. Sample sizes are presented as n/N (cell/animal number) and nested hierarchical analysis applied using a generalized linear mixed model (P<0.05). Results Pacing at a basic cycle length (CL, 350 ms) induced APD, Ca2+ transient amplitude (CaT) and sarcomere shortening alternans. The recapitulation of RSA through oscillatory pacing (OP), in which CL was set to 20% below and 20% above the corresponding basic CL in a 2-short, 2-long stimulus train, reduced the incidence of alternans. Furthermore, OP entrained APD, CaT and sarcomere shortening and this entrainment persisted in voltage clamp experiments with fixed APD. Using a three-step protocol to examine the dependence of APD and sarcomere shortening on both preceding (CLn-1) and anteceding (CLn-2) stimulus intervals, both APD and sarcomere shortening were found to depend directly on the preceding cycle length (CLn-1, P<0.001). In contrast, sarcomere shortening depended inversely on the anteceding CL (CLn-2, P<0.001; n/N = 24/4). Following treatment of the cells with caffeine (50 µM) to sensitise ryanodine receptors, the dependence of APD and sarcomere shortening on CLn-1 was markedly suppressed, and the inverse dependence of sarcomere shortening on CLn-2 was lost (P<0.001, n/N = 6/3). The effects of OP are akin to post-extrasystolic potentiation3 and mathematical simulation4 supports the involvement of changes in the sarcoplasmic reticulum Ca2+ content. Conclusion These data are consistent with an obligatory role for the SR in the entrainment of APD, CaT and sarcomere shortening and the suppression of alternans by the recapitulation of RSA. We hypothesise that recapitulation of RSA would be protective against ventricular tachyarrhythmia and further work is required to test this.

Public finance instruments and output growth in Nigeria

This study investigates the empirical relationship between the aggregated and disaggregated components of fiscal policy variables and output growth in Nigeria using the vector error correction mechanism for the period of 1981 to 2021. This formulation was an improvement over previous empirical studies of the impact of public finance instruments on output growth in Nigeria. Our findings suggest that fiscal policy instruments (total expenditure, capital expenditure, recurrent expenditure, total revenue, primary fiscal balance, domestic debt, external debt, oil tax revenue, and non-oil tax revenue) exert significant impacts on output growth and most of the empirical results obtained support the hypothesised relationships between public finance instruments and output growth in Nigeria. However, aggregate federal government expenditure exerts a significant negative impact on output growth, while on the disaggregated scale, capital expenditure exerts a significant positive influence on output growth whereas recurrent expenditure exerts a significant negative impact on output growth. Given these findings, we recommend that the government of Nigeria, through its fiscal authorities, should adopt growth-enhancing fiscal policies that would engender macroeconomic stability and will be potent in refocusing recurrent expenditure towards ensuring productivity growth.

Prospects for the implementation of the variable module "floorball" in the physical education curriculum for 14-16-year-old boys

The article deals with issues related to the development of floorball in general secondary education institutions. The presence of so-called variable modules within the current curriculum allows to vary to some extent the content of the educational material on physical culture in the direction of including the means of those types of sports and motor activity, which, on the one hand, are interesting and accessible to modern schoolchildren and, on the other hand, positively affect the level of their health and development. The purpose of the study is to determine the attitude of physical education teachers to the introduction of the "Floorball" module as a variable component of the physical education curriculum for 14-16-year-old boys. The research concept is based on the methodological, theoretical and scientific-methodical levels of the basic provisions of pedagogy and the theory and methodology of physical education. The research was carried out at Zhytomyr Ivan Franko State University and general secondary education institutions of Zhytomyr region in 2023-2024 in which 42 students - future physical education teachers - and 137 physical education teachers participated. Research methods: analysis of literary sources, observations, interviews, questionnaires, methods of mathematical statistics. Floorball is a team game sport and represents hockey in a sports hall. Simple equipment for the player, relatively inexpensive sports equipment made of plastic materials which makes it light and reduces the risk of injury, simple rules of the game and the ability to train on any flat surface. Floorball as a means of physical education attracts the attention of students with its high emotionality, spectacle, variety of manifestations of physical qualities, many different game combinations, quick transition from actions in attack to defense and ensures the preparation of student youth for active life activities and a healthy way of life. It was established that only 19.1% of the students have the skills and abilities to play floorball during a physical education lesson, and 71.4%, 66.1% and 63.0% of teachers with different work experience, respectively. The biggest obstacle to the introduction of floorball in lessons and extracurriculars in general secondary education institutions is the lack of sports grounds, the necessary equipment and the appropriate professional training of physical education teachers.

ORGANIZATIONAL AND MANAGEMENT CONDITIONS OF FORMATION OF PRIMARY EDUCATION CONTENT IN GREAT BRITAIN

The study is dedicated to identifying the peculiarities of the formation of the content of primary education in Great Britain. In the modern conditions of globalization the study of the main laws affecting the formation and modernization of primary education content in Great Britain is relevant and necessary for the domestic national education system development. The research aim: to reveal the organizational and managerial conditions for the formation of primary education content in Great Britain. Methods of research: analysis, synthesis, generalization, specification, and comparison. Primary education in Great Britain occupies a prominent place in the education system, it is the basis of schooling. The content of education, primary including, is based on a combination of three key components: the formation of a management system based on educational results; stimulation of diverse cooperation of education subjects; implementation of freedom of choice principles. The countryʼs educational policy is aimed at developing and modernizing the content of primary education while preserving the country culture and history. In Great Britain, organizational and management actions are considered in terms of modern trends of management decentralization and centralization in the field of school education. The model of strategic development, financing, and management of general school education is an organizational condition for the formation of the primary school education content. The British centralized model of school education is a single-state management of general education throughout the country. Standardization is the basis of the organizational and management model of the formation of the content of primary education, which is mandatory with a variable structural and content component, implemented through the National Curriculum. Formation of primary education content in Great Britain depends on many factors, including the basic organizational and management conditions, which is a model of strategic development, management, and financing of general school education.

Precision forecasting of fertilizer components’ concentrations in mixed variable-rate fertigation through machine learning

Accurate monitoring of fertilizer concentration and variable irrigation components is crucial for achieving precision irrigation through variable-rate fertigation. However, technological and cost constraints pose challenges in effectively managing mixed variable-rate fertigation. This study addresses these challenges by integrating machine learning (ML) with easily monitored physical parameters, such as electrical conductivity (EC), pH, and temperature, to predict fertilizer solution components and concentrations in mixed variable-rate fertigation. Cubic spline interpolation (CSI) was used to enhance the training dataset. Six ML algorithms—Multivariate Linear Regression (MLR), Support Vector Machines (SVM), K-Nearest Neighbors (KNN), Extremely Randomized Trees (ETs), Multilayer Perceptron (MLP), and Extreme Gradient Boosting (XGB)—were used to develop prediction models, with their performance evaluated using the coefficient of determination (R2), root mean square error (RMSE), and Akaike information criterion (AIC). The Extended Fourier Amplitude Sensitivity Test (EFAST) assessed the sensitivity of the ML models to physical parameters. All of the ML models, except for MLR, particularly SVM, demonstrated superior performance in predicting fertilizer solution components’ concentrations, with R2 values between 0.989 and 0.997 and RMSE values between 0.089 and 0.210. The CSI significantly enhanced model performance, resulting in larger R2 values and smaller RMSE values. The AIC results and sensitivity analysis confirmed the exceptional performance of SVM, emphasizing its suitability for predicting fertilizer components using easily measured physical parameters. The developed ML models offer valuable insights for decision-makers managing irrigation and fertilization in mixed variable-rate fertigation.

Technical note: An improved methodology for calculating the Southern Annular Mode index to aid consistency between climate studies

Abstract. The Southern Annular Mode (SAM) strongly influences climate variability in the Southern Hemisphere. The SAM index describes the phase and magnitude of the SAM and can be calculated by measuring the difference in mean sea level pressure (MSLP) between middle and high latitudes. This study investigates the effects of calculation methods and data resolution on the SAM index, and subsequent interpretations of SAM impacts and trends. We show that the normalisation step that is traditionally used in calculating the SAM index leads to substantial differences in the magnitude of the SAM index calculated at different temporal resolutions. Additionally, the equal weighting that the normalisation approach gives to MSLP variability at the middle and high southern latitudes artificially alters temperature and precipitation correlations and the interpretation of climate change trends in the SAM. These issues can be overcome by instead using a natural SAM index based on MSLP anomalies, resulting in consistent scaling and variability in the SAM index calculated at daily, monthly and annual data resolutions. The natural SAM index has improved representation of SAM impacts in the high southern latitudes, including the asymmetric (zonal wave-3) component of MSLP variability, whereas the increased weighting given to mid-latitude MSLP variability in the normalised SAM index incorporates a stronger component of tropical climate variability that is not directly associated with SAM variability. We conclude that an improved approach of calculating the SAM index from MSLP anomalies without normalisation would aid consistency across climate studies and avoid potential ambiguity in the SAM index, including SAM index reconstructions from palaeoclimate data, and thus enable more consistent interpretations of SAM trends and impacts.

The Leadership Influence on the Performance of Village-Owned Enterprise (BUMDesa) Employees of Lontar Sewu Gresik Regency

The aim of this research is to determine leadership influence on the performance of Village-Owned Enterprise (BUMDesa) Employees of Lontarsewu Gresik RegencyThe research used quantitative methods because it suits the purpose of this research, which aims to measure the leadership influence on the performance of BUMDesa Lontar Sewu employees, Hendrosari Village, Menganti District, Gresik Regency. Based on the results of processing, analysis, and discussion of research data, several points can be concluded as follows coefficient of determination value on the influence between leadership variables and employee performance is 0,55. Correlation coefficient value for the relationship between leadership variables and employee performance variables is 0,74 which interpreted as a strong level of relationship. It can be concluded that the better the leadership of the BUMDesa director, the better the performance of BUMDesa Lontar Sewu employees. The average value of the measurement components based on descriptive analysis of the leadership variable is 4,4 with a very successful interpretation; and the average value of the measurement component of the employee performance variable is 4,6 with a very high interpretation.

A New Model for Improving Quality of Hypertension’s Determinant Factors in Pregnancy

Background Hypertension in pregnancy should be detected earlier to prevent possible complications of pregnancy such as preeclampsia. Pregnancy hypertension could transform into preeclampsia if unmonitored and untreated, it can even be bad for eclampsia. Purpose This research aims to identify the determinant factors of hypertension during pregnancy and to develop a suitable model to prevent hypertension in the future. Methods The research was developed using a mixed method with an embedded design approach. This study has adopted the ADDIE concept including Analysis, Design, Development, Implementation, and Evaluation steps. Purposive sampling based on knowledge proportion has designated 164 pregnant women as key participants. Qualitative analysis was applied through in-depth interviews. Quantitative analysis was conducted with SEM-PLS. Results The determinant variable components of late detection of hypertension in pregnancy are knowledge and understanding, self-efficacy, intentions, and attitudes of pregnant women. Other variables are also considered as psychosocial support of husband/family and midwives, antenatal care, and service facilities. Conclusion The data shows that the MEGA model is proven to be effective in evaluating the determinant factors of hypertension in pregnancy.

Fixed and Variable Tax Expense and the Cost of Equity Capital

ABSTRACT Prior studies provide mixed evidence on the relation between tax avoidance and cost of equity capital. To understand how this relation varies across firms, we model income tax as containing both a fixed component (like a tax credit or deduction) and a variable component (a tax rate) and investigate how each type of tax expense affects the cost of equity capital. Unlike other fixed costs, the fixed tax component may be negative (a tax benefit). A lower fixed tax component always reduces cost of capital. The effect of a lower tax rate depends on the sign of the fixed tax component. With a negative fixed tax component, a lower tax rate increases cost of capital. Results of empirical tests are generally consistent with our predictions. Our results suggest the relation between cost of equity capital and tax avoidance is ambiguous when tax avoidance is accomplished through a lower tax rate. JEL Classifications: G12.

Using Shelf‐Edge Transport Composition and Sensitivity Experiments to Understand Processes Driving Sea Level on the Northwest European Shelf

AbstractVariability in ocean currents, temperature and salinity drive dynamic sea level (DSL) variability on the Northwest European Shelf (NWES). It is dominated by mass variations, with steric signals relatively small. A mechanistic explanation of how ocean dynamics relates to the mass component of NWES sea level variability is required. We use regional ocean model experiments to isolate sources of variability and then investigate the effect on monthly to‐interannual DSL variability together with the simulated momentum budgets along the shelfbreak. Regional (local) wind and non‐regional (remote) forcing are important on the NWES. For the local wind forcing, the net mass flux onto the shelf, which drives a shelf‐mean mode of DSL variability, results from a combination of surface Ekman, bottom Ekman and geostrophic flows and explains 73% of the variance in transport across the shelf‐edge. The geostrophic flow is closely related to wind stress with a flow about half that of surface Ekman transport but in the opposite direction. For the remotely forced mass‐flux across the shelf‐edge, the geostrophic component explains 62% of the variance and bottom friction plays an important indirect role. The remotely forced variability, while relatively spatially uniform, is more important for explaining DSL variance over the western NWES. This mode of variability is sensitive to signals propagating northward via a thin strip of the southern boundary near the Portuguese coast, consistent with coastal trapped wave signals. It also appears to drive steric height in the Bay of Biscay, which is related to DSL on the shelf.

Comparison for the effects of different components of temperature variability on mortality: A multi-country time-series study

BackgroundTemperature variability (TV) is associated with increased mortality risk. However, it is still unknown whether intra-day or inter-day TV has different effects. ObjectivesWe aimed to assess the association of intra-day TV and inter-day TV with all-cause, cardiovascular, and respiratory mortality. MethodsWe collected data on total, cardiovascular, and respiratory mortality and meteorology from 758 locations in 47 countries or regions from 1972 to 2020. We defined inter-day TV as the standard deviation (SD) of daily mean temperatures across the lag interval, and intra-day TV as the average SD of minimum and maximum temperatures on each day. In the first stage, inter-day and intra-day TVs were modelled simultaneously in the quasi-Poisson time-series model for each location. In the second stage, a multi-level analysis was used to pool the location-specific estimates. ResultsOverall, the mortality risk due to each interquartile range [IQR] increase was higher for intra-day TV than for inter-day TV. The risk increased by 0.59% (95% confidence interval [CI]: 0.53, 0.65) for all-cause mortality, 0.64% (95% CI: 0.56, 0.73) for cardiovascular mortality, and 0.65% (95% CI: 0.49, 0.80) for respiratory mortality per IQR increase in intra-day TV0–7 (0.9 °C). An IQR increase in inter-day TV0–7 (1.6 °C) was associated with 0.22% (95% CI: 0.18, 0.26) increase in all-cause mortality, 0.44% (95% CI: 0.37, 0.50) increase in cardiovascular mortality, and 0.31% (95% CI: 0.21, 0.41) increase in respiratory mortality. The proportion of all-cause deaths attributable to intra-day TV0–7 and inter-day TV0–7 was 1.45% and 0.35%, respectively. The mortality risks varied by lag interval, climate area, season, and climate type. ConclusionsOur results indicated that intra-day TV may explain the main part of the mortality risk related to TV and suggested that comprehensive evaluations should be proposed in more countries to help protect human health.

Circulating neuropeptide Y as a biomarker in postoperative atrial fibrillation cases administered off-pump coronary bypass Graft surgery

Background and aimsPostoperative atrial fibrillation (POAF) is considered the most prevalent irregular heart rhythm after heart surgery. The cardiac autonomic nervous system significantly affects POAF, and neuropeptide Y (NPY), an abundant neuropeptide in the cardiovascular system, is involved in this autonomic regulation. The current work aimed to examine the potential association of NPY with POAF in individuals administered isolated off-pump coronary artery bypass grafting. MethodsFrom January 1 to May 31, 2020, we examined consecutive cases administered successful isolated off-pump coronary artery bypass grafting with no previously diagnosed atrial fibrillation (AF). Clinical characteristics and plasma samples were collected before surgery. NPY was quantified by enzyme-linked immunosorbent assay (ELISA) in peripheral blood, and POAF cases were identified through a 7-day Holter monitoring. ResultsAmong 120 cases with no previously diagnosed AF, 33 (27.5 %) developed POAF during hospitalization. Median NPY levels were markedly elevated in the POAF group in comparison with the sinus rhythm group (31.72 vs. 27.95, P = 0.014). Multivariable logistic regression analysis revealed age (OR = 1.135, 95%CI 1.054–1.223; P = 0.001), left atrial size (OR = 1.136, 95%CI 1.004–1.285; P = 0.043), and NPY levels in peripheral blood (OR = 1.055, 95%CI 1.002–1.111; p = 0.041) independently predicted POAF. Additionally, NPY levels were positively correlated with high-frequency (HF) (r = 0.2774, P = 0.0022) and low-frequency (LF) (r = 0.2095, P = 0.0217) components of heart rate variability. ConclusionIn summary, this study demonstrates an association between elevated NPY levels in peripheral blood before surgery and POAF occurrence.

Non-physician anaesthesia providers’ perspectives on task sharing practices in Zambia and Somaliland: a qualitative study

IntroductionThe 68th World Health Assembly, in 2015, called for surgical and anaesthesia services strengthening. Acknowledging the healthcare staff shortages, they referred to task sharing, among others, as a more effective...

The Relationship Between Vitamin D Intake and Serum 25-hydroxyvitamin D in Young Children: A Meta-Regression to Inform WHO/FAO Vitamin D Intake Recommendations

BackgroundThis work was commissioned by the World Health Organization and Food and Agriculture Organization to inform their update on the vitamin D requirements for children aged <4 y. ObjectivesThe objective of this work was to undertake multilevel and multivariable dose-response modeling of serum 25-hydroxyvitamin D (25OHD) to total vitamin D intake in children aged <4 y with the goal of deriving updated vitamin D requirements for young children. MethodsSystematically identified randomized controlled trials among healthy children from 2 wk up to 3.9 y of age provided with daily vitamin D supplements or vitamin D-fortified foods were included. Linear and nonlinear random effects multilevel meta-regression models with and without covariates were fitted and compared. Interindividual variability was included by simulating the individual serum 25OHD responses. The percentage of individuals reaching set minimal and maximal serum 25OHD thresholds was calculated and used to derive vitamin D requirements. ResultsA total of 31 trials with 186 data points from North America, Europe, Asia, and Australasia/Oceania, with latitudes ranging from 61°N to 38°S, and with participants of likely mostly light or medium skin pigmentation, were included. In 29 studies the children received vitamin D supplements and in 2 studies the children received vitamin D-fortified milk with or without supplements. The dose-response relationship between vitamin D intake and serum 25OHD was best fitted with the unadjusted quadratic model. Adding additional covariates, such as age, did not significantly improve the model. At a vitamin D intake of 10 μg/d, 97.3% of the individuals were predicted to achieve a minimal serum 25OHD threshold of 28 nmol/L. At a vitamin D intake of 35 μg/d, 1.4% of the individuals predicted to reach a maximal serum 25OHD threshold of 200 nmol/L. ConclusionsIn conclusion, this paper details the methodological steps taken to derive vitamin D requirements in children aged <4 y, including the addition of an interindividual variability component.