Search

This paper deals with the mathematical modelling of the electrostatic spraying process in an industrial electrostatic oiling machine (EOM) for steel strips. Measurements from an industrial EOM show that the thickness and inhomogeneity of the oil film on the strips frequently exceed specified tolerance limits whereby the reasons were previously unknown. A numerical model of the spraying process is developed in ANSYS Fluent, which serves as the basis for a root-cause analysis of the erroneous oil film thickness. In contrast to other works in this area, a droplet break-up model, which describes the break-up of the oil droplets due to the charge they carry, is included to get more accurate results. The model is validated based on measurement data from an industrial oiling machine. It is demonstrated that the model yields a better understanding of the spraying process and it is successfully used to improve the oiling process. [ABSTRACT FROM AUTHOR]

The world is grappled with an unprecedented challenges due to Corona virus. We are all battling this epidemic together, but we have not been able to defeat this epidemic yet. A new variant of this virus, named 'Omicron' is spreading these days. The fractional differential equations are providing us with better tools to study the mathematical model with memory effects. In this paper, we will consider an extended SER mathematical model with quarantined and vaccinated compartment to speculate the Omicron variant. This extended Susceptible Exposed Infected Recovered SER model involves equations that associate with the group of individuals those are susceptible (S), exposed (E): this class includes the individuals who are infected but not yet infectious, infectious (W): this class includes the individuals who are infected but not yet Quarantined, quarantined (Q): this class includes those group of people who are infectious, confirmed and quarantined, recovered (R) this class includes the group of individuals who have recovered, and vaccinated (V): this class includes the group of individuals who have been vaccinated. The non-negativity and of the extended SER model is analysed, the equilibrium points and the basic reproduction number are also calculated. The proposed model is then extended to the mathematical model using AB derivative operator. Proof for the existence and the uniqueness for the solution of fractional mathematical model in sense of AB fractional derivative is detailed and a numerical method is detailed to obtain the numerical solutions. Further we have discussed the efficiency of the vaccine against the Omicron variant via graphical representation. [ABSTRACT FROM AUTHOR]

Leishmaniasis, an infectious disease, manifests itself mostly in two forms, cutaneous leishmaniasis (CL) and, a more severe and potentially deadly form, visceral leishmaniasis (VL). The current control strategy for leishmaniasis relies on chemotherapy drugs such as sodium antimony gluconate (SAG) and meglumine antimoniate (MA). However, all these chemotherapy compounds have poor efficacy, and they are associated with toxicity and other adverse effects, as well as drug resistance. While research in vaccine development for leishmaniasis is continuously progressing, no vaccine is currently available. However, some experimental vaccines such as LEISH-F1+MPL-SE (V) have demonstrated some efficacy when used as drugs for CL patients. In this paper we use a mathematical model to address the following question: To what extent vaccine shots can enhance the efficacy of standard chemotherapy treatment of leishmaniasis? Starting with standard MA treatment of leishmaniasis and combining it with three injections of V , we find, by Day 84, that efficacy increased from 29% to 65–91% depending on the amount of the vaccine. With two or just one injection of V , efficacy is still very high, but there is a definite resurgence of the disease by end-time. [ABSTRACT FROM AUTHOR]

Atherosclerosis is a leading cause of death worldwide. Making matters worse, nearly 463 million people have diabetes, which increases atherosclerosis-related inflammation. Diabetic patients are twice as likely to have a heart attack or stroke. In this paper, we consider a simplified mathematical model for diabetic atherosclerosis involving LDL, HDL, glucose, insulin, free radicals (ROS), β cells, macrophages and foam cells, which satisfy a system of partial differential equations with a free boundary, the interface between the blood flow and the plaque. We establish the existence of small radially symmetric stationary solutions to the model and study their stability. Our analysis shows that the plague will persist due to hyperglycemia even when LDL and HDL are in normal range, hence confirms that diabetes increase the risk of atherosclerosis. [ABSTRACT FROM AUTHOR]

Populations are generally censused daily, weekly, monthly or annually. In this paper, we introduce a discrete-time nutrients-phytoplankton-oysters (NPO) model that describes the interactions of nutrients, phytoplankton and oysters in a bay ecosystem. We compute the threshold parameter $ \mathcal {R}_N $ R N for persistence of phytoplankton with or without oysters. When $ \mathcal {R}_{N} \lt 1 $ R N < 1 , then both phytoplankton and oysters populations go extinct. However, when $ \mathcal {R}_N \gt 1 $ R N > 1 , we show that the model may exhibit two scenarios: (1) a locally asymptotically stable equilibrium with positive values of nutrients and phytoplankton with oysters missing, and (2) a locally asymptotically stable interior equilibrium with positive values of nutrients, phytoplankton and oysters. We use sensitivity analysis to study the impact of human and environmental factors on the model. We use examples to illustrate that some human activities and environmental factors can force the interior equilibrium to undergo a Neimark–Sacker bifurcation which generates phytoplankton blooms with oscillations in oysters population and nutrients level. [ABSTRACT FROM AUTHOR]

This paper explores the prospects of commercial producers who would be willing to exit voluntarily in the near future to make land available in the market. In addition, it also considers what factors are restricting the acceleration of this rate of exit from a land-supply perspective with respect to barriers to exit. The prospect of structural change from such acceleration is also explored using three scenarios. An agent-based mathematical model is used to implement the three scenarios. This model is constructed from a dataset of 450 commercial producers across South Africa. The results suggest that a reasonable amount of arable land could be available for redistribution, with only modest structural change regarding animal production, despite drastic alterations in veld. These results provide some guidelines on how assistance for struggling producers can make land available for efficient producers, which could make the sector stronger. All potential exiting commercial producers have common reasons for doing so, which could be used to initiate a positively inclined, structured discussion on land supply. [ABSTRACT FROM AUTHOR]

This paper proposes a mathematical model approach to predict the Ultrasonic Pulse Velocity (UPV) of concrete. This paper presents the formulation, calibration, evaluation, and validation of the proposed UPV model. An experimental program was developed to calibrate and evaluate the proposed model. Furthermore, the model was validated using a separate group of measurements in the experimental program, to test its accuracy and generalization capability. Analysis of the results reveals that the proposed model provides a good fit to the experimental data and does not contain outliers or discerning pattern. The corresponding standard error and determination coefficient are 45 m/s and 0.92, respectively. Model validation demonstrates high predictability and generalization capability. The corresponding standard error and determination coefficient are 74 m/s and 0.91, respectively. [ABSTRACT FROM AUTHOR]

The primary objective of this work is to investigate the existence of mild solutions for some neutral stochastic integrodifferential systems in Hilbert spaces. These systems have a state-dependent delay and noninstantaneous impulses. In order to achieve this objective, the neutral stochastic integrodifferential system that has been proposed with state-dependent delay and noninstantaneous impulses is converted into an equivalent fixed point problem by means of an appropriate integral operator.Together with the theory of stochastic analysis, we develop several existence results that are founded on the theory of resolvent operators in the sense of Grimmer, Hausdorff's measures of noncompactness, and fixed point theorems.In the last part of this paper, specific examples are used to show how the general conclusions reached in this paper are made. [ABSTRACT FROM AUTHOR]

Considering carbon emissions when making supply chain decisions has been an essential contributor for keeping this world more sustainable. This paper presents a mixed-integer linear programming (MILP) model to optimize production and transportation decision where the transportation activities involve a multimodal combination. The proposed mathematical model was aimed at mini- mizing the total costs incurred from supply chain activities as well as the emissions generated. Carbon cap is used to ensure that the emissions produced in the whole activities do not exceed the allowable limit. In this research, we address a multi- product, multi-plant, multi-departure, and arrival stations where multiple customers are to be served for multiple periods. The numerical tests show that the demand, carbon tax, and distance significantly affected the total emissions and the total costs. Interestingly, we observed that the decisions are much more affected by the logistical costs rather than the emission costs. The model presented in this paper can assist the decision makers to make production, delivery, and inventory decisions when multi-modal transportation is involved. [ABSTRACT FROM AUTHOR]

Building fair, equitable, and beneficial partnerships between institutions collaborating in research in low- and middle-income countries (LMIC) and high-income countries (HIC) has become an integral part of research capacity building in global health in recent years. In this paper, we offer an example of an academic collaboration between the University of California Los Angeles, Center for Health Policy and Research (UCLA CHPR) and the University of Philippines, Manila, College of Public Health (UPM CPH) that sought to build an equitable partnership between research institutions. The partnership was built on a project to build capacity for research and produce data for policy action for the prevention and care of non-communicable diseases (NCDs) through primary healthcare in the Philippines. The specific objectives of the project were to: (1) locally adapt the Primary Care Assessment Tool for the Philippines and use the adapted tool to measure facility-level primary care delivery, (2) conduct focus group discussions (FGDs) to gather qualitative observations regarding primary care readiness and capacity, and (3) conduct a comprehensive population-based health survey among adults on NCDs and prior healthcare experience. We describe here the progression of the partnership between these institutions to carry out the project and the elements that helped build a stronger connection between the institutions, such as mutual goal setting, cultural bridging, collaborative teams, and capacity building. This example, which can be used as a model depicting new directionality and opportunities for LMIC-HIC academic partnerships, was written based on the review of shared project documents, including study protocols, and written and oral communications with the project team members, including the primary investigators. The innovation of this partnership includes: LMIC-initiated project need identification, LMIC-based funding allocation, a capacity-building role of the HIC institution, and the expansion of scope through jointly offered courses on global health. [ABSTRACT FROM AUTHOR]

The paper's main aim is to investigate the 2019 coronavirus disease in Ethiopia using a fractional-order mathematical model. It would also focus on the importance of fractional-order derivatives that may help us in modelling the system and understanding the effect of model parameters and fractional derivative orders on the approximate solutions of our model. A SELAIQHCR model is constructed using nonlinear differential equations in the Atangana–Baleanu non-integer operator in the Caputo sense. After that, the Chebyshev fourth kind spectral collocation method is used to change a fractional system to an algebraic system. Newton iterative technique is used to solve the converted system. The next-generation matrix technique is used to obtain the effective reproduction number. The COVID-19-free equilibrium point and endemic equilibrium point, solution positivity and boundedness, and their stability are all carefully done. The sensitivity of the effective reproduction value with respect to the key model parameters is discussed. The beginning values provided for our system were obtained using reports from the Ethiopian Public Health Institute from 29 February 2021 to 7 June 2021. The fundamental reproduction number is obtained with R 0 = 1.4331. The model's numerical solutions are represented graphically. [ABSTRACT FROM AUTHOR]

The goal of this paper is to investigate the influence of the waning immunity on the dynamics of Tilapia Lake Virus (TiLV) transmission in wild and farmed tilapia within freshwater. We formulate a model for which susceptible individuals can contract the disease in two ways: (i) direct mode caused by contact with infected individuals; (ii) indirect mode due to the presence of pathogenic agents in the water. We obtain an age-structured model which combines both age since infection and age since recovery. We derive an explicit formula for the reproductive number R 0 and show that the disease-free equilibrium is locally asymptotically stable when, R 0 < 1. We discuss on the form of the waning immunity parameter and show numerically that a Hopf bifurcation may occur for suitable immunity parameter values, which means that there is a periodic solution around the endemic equilibrium when, R 0 > 1. [ABSTRACT FROM AUTHOR]

The tubeless vortex reducer was used to reduce the pressure drop in a cavity with radial inflow. In previous studies, the mechanism of vortex breakdown in tubeless vortex reducers was not clear, and there was a lack of direct guidance for engineering design. In this paper, we studied the vortex and pressure in the cavity in detail by large-eddy simulation (LES) and experiments. A mathematical model, which has high applicability and compatibility, was established to guide the pre-design of tubeless vortex reducers. The LES results showed that the high-speed and large-scale vortices broke rapidly at the nozzle inlet and reached the minimum size at the nozzle outlet. Furthermore, the enhancement of vortex in the downstream cavity was restrained. When the rotating speed was relatively low, strong negative vortices formed and the pressure drop increased in the downstream cavity. The experiments showed that the nozzle performance directly affected the flow characteristics and pressure drop in the cavity. Compared with the simple cavity, the tubeless vortex reducer generated lower pressure drop. The average relative error between the mathematical model and the experimental results was only 9.3%. [ABSTRACT FROM AUTHOR]

Variable-thickness rolled blank (VRB) technique is one of the most effective methods to improve the level of lightweight and stiffness characteristics of car body. The shape of thickness transition zone (TTZ) is a key factor for the stiffness characteristics of VRB. For better stiffness characteristics of VRB, a new thickness distribution function (i.e. double-power function) of the transitional zone of VRB is proposed in this paper. Firstly, the mathematical model of the VRB with double-power thickness distribution function is established under manufacturing constraint. Secondly, the static stiffness characteristics of VRB with double-power thickness distribution function are compared with that of the VRB with linear thickness distribution and polynomial thickness distribution under the same weight, respectively. The results show that the static stiffness of the VRB with double-power thickness distribution function owns best characteristics. Finally, the mathematical model of the rolling velocity is established, and the influence of the shape of double-power TTZ on rolling velocity is analysed. The outcome of this work can provide some useful guidance for investigating the rollability of the VRB with double-power thickness distribution function, as well as for designing the stiffness of car body outer panels. [ABSTRACT FROM AUTHOR]

The outbreak of COVID-19 was first experienced in Wuhan City, China, during December 2019 before it rapidly spread over globally. This paper has proposed a mathematical model for studying its transmission dynamics in the presence of face mask wearing and hospitalization services of human population in Tanzania. Disease-free and endemic equilibria were determined and subsequently their local and global stabilities were carried out. The trace-determinant approach was used in the local stability of disease-free equilibrium point while Lyapunov function technique was used to determine the global stability of both disease-free and endemic equilibrium points. Basic reproduction number, R 0 , was determined in which its numerical results revealed that, in the presence of face masks wearing and medication services or hospitalization as preventive measure for its transmission, R 0 = 0.698 while in their absence R 0 = 3.8. This supports its analytical solution that the disease-free equilibrium point E 0 is asymptotically stable whenever R 0 < 1 , while endemic equilibrium point E ∗ is globally asymptotically stable for R 0 > 1. Therefore, this paper proves the necessity of face masks wearing and hospitalization services to COVID-19 patients to contain the disease spread to the population. [ABSTRACT FROM AUTHOR]

In this paper, we investigate a non-linear Langevin equation with periodic, multi-point and non-local fractional integral boundary conditions. The contraction mapping theorem is employed to determine sufficient conditions for the uniqueness of the solution. Also, different results in the existence of solution are demonstrated by using Krasnoselskii and Leray-Schauder theorems. Finally, some examples are provided as applications of the theorems in order to support the main outcomes of this paper. [ABSTRACT FROM AUTHOR]

The paper presents the results of a study done to find the optimal shapes of matrix element partitioning on three abstract heterogeneous processors when performing multiplication operations. An abstract processor model allows applying the research results in systems with different heterogeneous architectures. To determine the optimal partitioning shape, the work uses non-rectangular candidate shapes identified by Ashley DeFlumere in her work as a result of applying the technology of redistribution of matrix elements between the processors «push»: Square Corner, Rectangle Corner, Square Rectangle, Block Rectangle, L-Rectangle, Traditional 1D Rectangular. The optimality of shapes is determined for four classes of matrix multiplication algorithms: Serial Communication with Barrier (SCB), Parallel Communication with Barrier (PCB), Serial Communication with Bulk Overlap (SCO) and Parallel Communication with Overlap (PCO). The Hockney model was used to evaluate the communication complexity of algorithms. Mathematical models of the algorithm execution time were introduced in the paper for each considered candidate shape in all algorithms. Based on the developed mathematical models, software was developed that allows to select the form of elements partitioning between processors, depending on the ratio of their speeds and latency of the transmission medium. [ABSTRACT FROM AUTHOR]

In this paper, we give a geometric construction for different allowable properties for sign pattern matrices. In Section 2, we give a construction for detecting a sign pattern matrix to be potentially nilpotent and also compute the nilpotent matrix realization for a given sign pattern matrix if it exists. In Section 3, we develop a geometric construction for potential stability. In Section 4, we establish a necessary and sufficient condition for a sign pattern matrix S to be spectrally arbitrary. For a given sign pattern matrix of order n , we prove that there exists a surface of dimension at most m for m ≤ n such that for every vector a 1 , a 2 , ⋯ , a n on the same surface, there exists a matrix A ∈ Q (S) , a qualitative class of S whose characteristic polynomial is x n − a 1 x n − 1 + ⋯ + (− 1) n a n . [ABSTRACT FROM AUTHOR]

Unwanted dispersive wiggles that arise from the leapfrog numerical scheme have been of interest in weather research and other fluid flow studies. A number of differing approaches have been developed over the last few decades to suppress such wiggles. For example, there are methods that use either smoothing filters or adaptive time-stepping. But, in addition to suppressing the wiggles, smoothing filters suppress the solution profile as well. In order to overcome this problem, in this paper, we construct a computationally efficient numerical scheme that simply eliminates the dispersive wiggles while keeping the solution profile intact. [ABSTRACT FROM AUTHOR]

We present in this paper further mathematical properties of the Odd Kappa-G family of distributions. These structural properties of this family hold for any baseline model including characterizations results based on two truncated moments and hazard and reversed hazard functions. In addition, k th lower record values and extreme values of this Odd Kappa-G family are introduced. Lastly, the bivariate probability distributions of the Odd Kapp-G (BFGMOKG) family based on FGM copula are obtained. [ABSTRACT FROM AUTHOR]

This paper examines a new class of Möbius invariant function spaces, denoted by N K (p , q) -type spaces in the unit ball of C n , which are a common basis for several known spaces of holomorphic functions. We establish several basic properties of N K (p , q) -type spaces and its closed subspaces N K , 0 (p , q) , which are Banach spaces of holomorphic functions with norms determined by a weighted nondecreasing function K : [ 0 , ∞) → [ 0 , ∞) , together with a Möbius transformation. With Green's function, we give an equivalent description of N K (p , q) -type spaces. Finally, we study the Hadamard gap series in N K (p , q) -type spaces. [ABSTRACT FROM AUTHOR]

The evidential approach uses likelihood ratios, typically the natural logarithm of the likelihood ratio representing the amount of evidence for one hypothesis versus another. One of the barriers to using the approach is the unavailability of sample size calculations for commonly used statistical tests. The t test is the most common statistical test used in scientific publications. This paper derives the equations necessary to calculate evidential probabilities and hence the required sample size for different types of t tests. Compared with the conventional Neyman-Pearson approach, the evidential approach requires larger sample sizes. This drawback is countered by the fact that users know the probability for obtaining misleading evidence (strong evidence that points to the wrong hypothesis). Even with small sample sizes, this is quite small (around 0.05) and decreases further with increasing sample sizes. The main challenge faced by the evidential researcher is of obtaining sufficiently strong evidence for or against one of the two specified hypotheses. Like the probability of a Type II error, this probability is large with a small sample size and decreases as the sample size increases. Sample size is estimated by achieving a low probability (e.g. <.1) for the combined probability of misleading and weak evidence. [ABSTRACT FROM AUTHOR]

In this paper, we propose and analyze a detailed mathematical model describing the dynamics of a prey-predator model under the influence of an SIS infectious disease by using nonlinear differential equations. We use the functional response of ratio-dependent Michaelis-Menten type to describe the predation strategy. In the presence of the disease, prey and predator population are divided into two disjointed classes, namely infected and susceptible. The first one is governed through due predation interaction, and the second one is governed through the propagation of disease in the prey and predator population via predation. Our aim is to analyze the effect of predation on the dynamic of the disease transmission. Important mathematical results resulting from the transmission of the disease under influence of predation are offered. First, results concerning boundedness, uniform persistence, existence and uniqueness of solutions have been developed. In addition, many thresholds have been computed and used to investigate local and global stability analysis by using Routh-Hurwitz criterion and Lyapunov principle. We also establish the Hopf bifurcation to highlight periodic fluctuation with persistence of the disease or without disease in the prey and predator population. Finally, numerical simulations are carried out to illustrate the feasibility of the theoretical results. [ABSTRACT FROM AUTHOR]

In this paper, an extended SIRB deterministic epidemiological model for Cholera was developed and strictly analysed to ascertain the impact of immigration in cholera transmission and to assess the suitability of the various control measures. The model was found to have two equilibria, namely, disease-free equilibrium (DFE) and a unique endemic equilibrium (EE). The local stability of the DFE and EE were found to be dependent on a certain epidemiological threshold known as the basic reproductive number, R 0 (number of secondary infections resulting from the introduction of a single infected individual into a population), in that DFE is stable when R 0 < 1 , whereas the EE is stable when R 0 > 1. Furthermore, we used the Lyapunov function and geometric approach respectively to show that the DFE and EE are globally asymptotically stable and that Cholera will persist in the population when R 0 > 1. Our model was fitted to Uganda Cholera cases (1999–2015). The best fit parameters were then used to carry out numerical simulation of the model. Specifically, the impact of the control over the long and short cycle transmission routes were found to be more effective than vaccination in combating the menace of Cholera in Uganda. Finally, the effects of immigration in the transmission of cholera were validated via numerical simulation using estimated and base line parameter values. [ABSTRACT FROM AUTHOR]

The oil industry in Thailand primarily relies on truck transportation due to the versatility of trucks. Different truck sizes can easily access many customer locations better than any other transportation mode. However, although trucks have many advantages, the transportation cost per unit is very expensive compared to railway, air, waterway, and pipe transportation modes. Previous data indicated that shipping costs were approximately 703.995 USD/month/fleet and the transportation utilization was 83.145%. Therefore, efficiencies should be identified to improve business operations. This paper proposes an oil transportation plan with transshipment points by adopting Network Flow Models (NFM) to develop a Generalized Network Flow Model (GNFM). The developed GNFM was applied to solve three different problems and compared to the existing method. The objectives of the proposed model were to minimize total cost and maximize truck efficiency. Multi-Criteria Decision Analysis (MCDA) was considered to set the optimal decision criteria for managing the oil transportation network with the transshipment sites. The proposed model with the Cluster Model (CT) provided optimal results, with a total cost of 663.539 USD/month/fleet and a truck efficiency of 88.029%. [ABSTRACT FROM AUTHOR]

Purpose: Understanding the nature of wellbeing as multidimensional and complex provides a policy window to generate a strengths-based policy orientation to promote wellbeing in education settings. The purpose of this exploratory paper is to map how wellbeing is interpreted across public education policy documents in Aotearoa New Zealand. Method: To explore the narrative that this group of documents weave, we draw on models of holistic wellbeing, ecological systems and appreciative inquiry. Policy documents were analysed using text mining software to track notions of wellbeing; their occurrence and co-occurrence with related concepts. Results: Key findings include the predominance of wellbeing, the interrelatedness of wellbeing with relationships, and the predominance of student wellbeing over the wellbeing of other stakeholders, highlighting that current education policy does not interpret wellbeing as relational, complex or contextual. Conclusion: We argue that interpreting such documents through a wellbeing lens demonstrates the complexity and disparity of the conceptualization and contextualization. We assert that it is critical to explore possibilities for deliberate and ecological wellbeing connections within educational policy and practice for the good of all stakeholders. [ABSTRACT FROM AUTHOR]

Modelling the human cardiorespiratory system using computer simulation tools can serve to help physicians to comprehend the causes and development of cardiorespiratory diseases. The objective of this paper is to develop an integrated model of the cardiovascular and respiratory systems, along with their intrinsic control mechanisms, by combining analogous hydraulic-electric and diffusion-electric circuits, respectively. This modelling task is performed in object-oriented language in SIMSCAPE using the physical interconnected components to define the underlying dynamic equations. Simulation steady state results under rest and under variable physical exercise conditions, as well as under limiting conditions show a high qualitative agreement with clinical observations reported in literature. This object-oriented modelling approach, based on the combined use of electrical analogies, proves to be avaluable tool as a test bench for different strategies aimed to qualitative prediction of the effects of cardiorespiratory interactions during exercise, thus avoiding the formulation of complex mathematical models. [ABSTRACT FROM AUTHOR]

Since mathematical models play a key role in investigating the dynamics of infectious diseases, many mathematical models for these diseases are developed. In this paper, it is aimed to determine the dynamics of Tuberculosis (TB) in Turkey, how much it will affect the future and the impact of vaccine therapy on the disease. For this purpose, three mathematical models (SIR, SEIR and BSEIR) in the literature are considered for the case of Turkey. The model parameters are obtained with TB reported data from 2005 to 2015 by using the least square method. The obtained results revealed that the basic reproduction ratio for all three models is less than 1. Moreover, the stability analysis of the models and sensitivity analysis of the model parameters are presented and discussed. Finally, the accuracy of results for all three models is compared and the effect of the vaccination rate is discussed. [ABSTRACT FROM AUTHOR]

Self-medication is an important initial response to illness in Africa. This mode of medication is often done with the help of African traditional medicines. Because of the misconception that African traditional medicines can cure/prevent all diseases, some Africans may opt for COVID-19 prevention and management by self-medicating. Thus to efficiently predict the dynamics of COVID-19 in Africa, the role of the self-medicated population needs to be taken into account. In this paper, we formulate and analyse a mathematical model for the dynamics of COVID-19 in Cameroon. The model is represented by a system of compartmental age-structured ODEs that takes into account the self-medicated population and subdivides the human population into two age classes relative to their current immune system strength. We use our model to propose policy measures that could be implemented in the course of an epidemic in order to better handle cases of self-medication. [ABSTRACT FROM AUTHOR]

Between February and May 2020, New Zealand recorded 1504 cases of COVID-19 before eliminating community transmission of the virus in June 2020. During this period, a series of control measures were used including population-wide interventions implemented via a four-level alert system, border restrictions, and a test, trace, and isolate system. Mathematical modelling played a key role in informing the government response and guiding policy development. In this paper, we describe the development of a stochastic mathematical model for the transmission and control of COVID-19 in New Zealand. This includes features such as superspreading, case under-ascertainment, testing and reporting delays, and population-wide and case-targeted control measures. We show how the model was calibrated to New Zealand and international data. We describe how the model was used to compare the effects of various interventions in reducing spread of the virus and to estimate the probability of elimination. We conclude with a discussion of the policy-modelling interface and preparedness for future epidemic outbreaks. [ABSTRACT FROM AUTHOR]

In this paper, we obtain a closed formula for the Kostant's partition function for the Lie algebras sl4(C) and sp6(C): Using this function, one can compute the weight multiplicity of irreducible representations of the Lie algebras sl4(C) and sp6(C). [ABSTRACT FROM AUTHOR]

Let M be a real hypersurface in a Sasakian space form M ‾ (c). In this paper, we prove that if R U L U = L U R U holds on M , then M is a Hopf hypersurface, where R U and L U denote the Jacobi operator structure and the induced operator from the Lie derivative with respect to the induced normal vector field U , respectively. We characterize such the Hopf hypersurfaces of M ‾ (c). [ABSTRACT FROM AUTHOR]

The paper reports a new mathematical model for understanding the mechanism delivery from drug release systems. To do this, two drug release systems based on chitosan and diclofenac sodium salt as a drug model, were prepared by in situ hydrogelation in the presence of salicylaldehyde. The morphology of the systems was analyzed by scanning electron microscopy and polarized light microscopy and the drug release was in vitro investigated into a medium mimicking the in vivo environment. The drug release mechanism was firstly assessed by fitting the in vitro release data on five traditional mathematical model. In the context of pharmacokinetics behavioral analysis, a new mathematical procedure for describing drug release dynamics in polymer-drug complex systems was proposed. Assuming that the dynamics of polymer-drug system's structural units take place on continuous and nondifferentiable curves (multifractal curves), it was showed that in a one-dimensional hydrodynamic formalism of multifractal variables the drug release mechanism is given through synchronous dynamics at a differentiable and non-differentiable scale resolutions. [ABSTRACT FROM AUTHOR]

Scarlet fever is an acute respiratory infectious disease and the incidence rate is increasing from 2011 throughout the world. In this paper, the mathematical models are proposed, which incorporate both direct transmissions and indirect transmissions of scarlet fever. The threshold conditions for disease invasion are obtained in terms of the basic reproduction number. The peak value, final size and epidemic time in a seasonal prevalence are investigated numerically. Furthermore, the effects of seasonal fluctuations on disease outbreak are also studied on the basis of real data in China. [ABSTRACT FROM AUTHOR]

Demands for out-of-hours primary care (OOH-PC) services are increasing. Many citizens call because of non-urgent health problems. Nevertheless, the patients' motives for requesting medical help outside office hours remains an understudied area. This study aimed to examine motives for calling OOH-PC services in various age groups. Cross-sectional paper based questionnaire study conducted during two weeks in 2015. The OOH-PC services in two Danish regions. Randomly selected patients calling the two healthcare services and accepting to participate in the study received a questionnaire on patient characteristics, health problems, and 26 pre-defined motives based on the Andersen Behavioural Model. Multivariate regression analyses were conducted for various age groups to calculate the probability of each motive to be a significant factor for the decision to call. A total of 1,871 patients were included in the study; half were parents of children aged 0-12 years. Young adults (18 to 39 years) differed significantly from other age groups as they more often stated perceived barriers and benefits such as "Own GP no time available soon enough" and "Need for quick help because of work". Young adults more often perceive barriers and benefits, which may suggest af difference in expectations regarding the purpose of out-of-hours services and accessibility. Further research is needed to address this issue and further explore the potential gap between the citizens' expectations to the OOH-PC services and the prevailing health policies. The out-of-hours primary healthcare services are increasingly contacted for non-urgent problems, but little is known about the citizens' motives for calling. Age is associated with differences in the perceived importance of various motives for calling out-of-hours care. Young adults are more often than other age groups motivated to call due to logistical issues, such as their job. [ABSTRACT FROM AUTHOR]

Background: The United Nations 2030 Sustainable Development Goals have reaffirmed the international community's commitment to maternal, newborn, and child health, with further investments in achieving quality essential service coverage and financial protection for all. Objective: Using a modified version of the 1978 Tanahashi model as an analytical framework for measuring and assessing health service coverage, this paper aims to examine the system of care at the community level in Ghana's Volta Region to highlight the continued reforms needed to achieve Universal Health Coverage. Methods: The Tanahashi model evaluates health system coverage through five key measures that reflect different stages along the service provision continuum: availability of services; accessibility; initial contact with the health system; continued utilization; and quality coverage. Data from cross-sectional household and health facility surveys were used in this study. Immunization and antenatal care services were selected as tracer interventions to serve as proxies to assess systems bottlenecks. Results: Financial access and quality coverage were identified as the biggest bottlenecks for both tracer indicators. Financial accessibility, measured by enrollment in Ghana's National Health Insurance Scheme was poor with 16.94% presenting valid membership cards. Childhood immunization was high but dropped modestly from 93.8% at initial contact to 76.7% quality coverage. For antenatal care, estimates ranged from 65.9% at initial visit to 25.1% quality coverage. Conclusion: Results highlight the difficulty in achieving high levels of quality service coverage and the large variations that exist within services provided at the primary care level. While vertical investments have been prioritized to benefit specific health services, a comprehensive systems approach to primary health care needs to be further strengthened to reach Ghana's Universal Health Coverage objectives. [ABSTRACT FROM AUTHOR]

In this paper, we study an excision theorem of the dihedral and reflexive (co)homology theory of associative algebras. That is, for such an extension, we obtain a six-term exact sequence in the dihedral cohomology. Also, we present and prove the relation between cyclic and dihedral cohomology of algebras and some examples. [ABSTRACT FROM AUTHOR]

This paper deals with the numerical solution of singularly perturbed parabolic convection-diffusion problems with two small positive parameters multiplying the convection and diffusion terms. A parameter-uniform computational method is developed to solve these problems. The stability and consistency of the method are well established. Numerical experimentation is done and it is observed that the formulated method is stable, consistent and gives more accurate results than some methods exist in the literature. [ABSTRACT FROM AUTHOR]

In this paper, it has been proved that if a 3-dimensional cosymplectic manifold M 3 admits a Yamabe soliton, then either M 3 is locally flat or the potential field is a contact vector field. Some special potential vector fields of Yamabe solitons on 3-dimensional cosymplectic manifolds have been considered and some other results have been obtained. Also, for general (2 n + 1) -dimensional case, it will be shown that if an f − cosymplectic manifold M 2 n + 1 admits a contact Yamabe soliton structure, then M 2 n + 1 is a cosymplectic manifold. Finally, an example of Yamabe soliton on a 3-dimensional cosymplectic manifold is provided. [ABSTRACT FROM AUTHOR]

In this paper, by applying the behavior of measure of noncompactness in L∞( R n), we study the existence of solutions of an infinite system of integral equations in the space L∞( R n). Finally, an example is included to show the usefulness of the outcome. [ABSTRACT FROM AUTHOR]

Most of High-impedance faults (HIFs) occur due to broken conductors falling on high-resistivity desert soil in United Arab Emirates remain undetected due to incredibly low fault currents and endanger lives. A reliable detection method is needed. A live line test conducted on a 11kV distribution line by switching to a remotely laid conductor did not result enough detectable fault currents. This motivated conducting a literature survey and researching for the reasons why the modern numerical protection relays could not detect such low current faults. Hence, a sensitivity analysis of a single-phase-to-ground system is carried out. Mathematical modelling for the sensitivity analysis is performed using differential calculus. Applying definition of sensitivity to a set of power system equations to analyze to provide guidance for detection of high impedance faults is entirely a new approach. This paper provides a comprehensive analysis of single phase to ground fault system by exhibiting profiles of fault currents, line, neutral, and MV bus voltages for a range of fault impedance. The sensitivity analysis results conclude that low-fault current signals should be collected from the neutral line of the distribution system instead of focusing on the line voltage, current, power and other parameters. [ABSTRACT FROM AUTHOR]

This paper first introduces the structure and working principle of a 2D piston pump invented by the research team that the authors are involved with. Afterward, the mechanism of the churning losses caused by the pump's moving parts, which are rotating in oil, is carefully studied by building up mathematical models and using CFD simulations. A test rig is set up to estimate the churning losses of the moving parts by monitoring the torque at different rotational speeds. The analytical results indicated that the torque of the churning losses increased with the increase of the rotational speed. In addition, the experimental data of the churning losses were consistent with the solutions from both the conducted mathematical models and CFD simulations before the rotational speed reached 8000 rpm. However, when the rotational speed exceeded 8000 rpm, the experimental data showed an apparent difference from the calculated ones. Based on the changes in the oil temperature and noise, this difference might be due to cavitation or turbulence. As a result, the churning losses that took place in the 2D high-speed piston pump need to be further studied, especially when the pump is driven by a high-speed motor. [ABSTRACT FROM AUTHOR]

Incipient motion of non-cohesive sediment, as a branch of water erosion, has been studied for decades, and criteria proposed in predicting incipient motion mainly focus on dimensionless shear stress and shear velocity. The two parameters could provide runoff erosive power, however, are invisible and not easy-measured in experiment. In this paper, critical runoff depth was recognized as another parameter, which is visible, measurable, and closely connected with shear velocity. To get it, a mathematical model coupling surface flow and subsurface flow was established, and they are governed by Navier‒Stokes equation and Brinkman‒extended Darcy equation, respectively. Velocity derived from the model could be indirectly applied in particle force analysis and finally a new criterion about critical runoff depth was obtained. Accuracy of the criterion was verified by comparison of experimental and theoretical values, e.g. theoretical critical runoff depth ranges from 2.71 ∼ 1.14 mm with a slope angle range of 20 ∼ 28° and mean particle diameter of 2.5 mm while the corresponding experiment values ranges from 3 ∼ 1 mm and the absolute errors are less than 0.3 mm. Compared with Yang's formula, this criterion could also be applied in predicting incipient motion of non-cohesive sediment for its significant advantages of high accuracy and concise formulation. [ABSTRACT FROM AUTHOR]

In this paper, we consider a system of delay differential equations that models the oncolytic virotherapy on solid tumours with the delay of viral infection in the presence of the innate immune response. We conduct qualitative and numerical analysis, and provide possible medical implications for our results. The system has four equilibrium solutions. Fixed point analysis indicates that increasing the burst size and infection rate of the viruses has positive contribution to the therapy. However, increasing the immune killing infection rate, the immune stimulation rate, or the immune killing virus rate may lead the treatment failed. The viral infection time delay induces backward Hopf bifurcations, which means that the therapy may fail before time delay increases passing through a Hopf bifurcation. The parameter analysis also shows how saddle-node and Hopf bifurcations occur as viral burst size and other parameters vary, which yields further insights into the dynamics of the virotherapy. [ABSTRACT FROM AUTHOR]

In this paper, we establish a mathematical model with two delays to reflect the intrinsic and extrinsic incubation periods of virus in dengue transmission. The basic reproduction number R 0 of the model is defined. It is proved that the disease-free equilibrium is stable when R 0 < 1 and the positive equilibrium is stable when R 0 > 1. Next, we derive an estimation formula for the reproduction number R t when the human population is partially susceptible to dengue. As an application, the R t values of dengue transmission in Singapore in the years 2013–2015 are estimated. Our estimation method can be applied to estimating R t of other infectious diseases, especially when the human population is not completely susceptible to the disease. [ABSTRACT FROM AUTHOR]

Among the various techniques of power scavenging, piezoelectric energy harvesting usually has more power density. Although piezoceramics are usually more efficient than other piezoelectric materials, since they are very brittle and fragile, researchers are looking for alternative materials. Recently Cellulose Electro-active paper (EAPap) has been recognized as a smart material with piezoelectric behavior that can be used in energy scavenging systems. The majority of researches in energy harvesting area, use unimorph piezoelectric cantilever beams. This paper presents an analytical solution based on distributed parameter model for partially covered pieoelectric cantilever energy harvester. The purpose of the paper is to describe the changes in generated power with damping and the load resistance using analytical calculations. The analytical data are verified using experiment on a vibrating cantilever substrate that is partially covered by EAPap films. The results are very close to each other. Also asymptotic trends of the voltage, current and power outputs are investigated and expressions are obtained for the extreme conditions of the load resistance. These new findings provide guidelines for identification and manipulation of effective parameters in order to achieve the efficient performance in different ambient source conditions. [ABSTRACT FROM PUBLISHER]

Child health is taking the back seat in development strategies. In summarising a newly released collaborative report, this paper calls for a novel conceptual model where child health takes centre stage in relation to the 2030 Agenda and the Sustainable Development Goals. It lays out five principles by which renewed effort and focus would yield the most benefit for children and adolescents. These include: re-defining global child health in the post-2015 era by placing children and adolescents at the centre of the Sustainable Development Goals; striving for equity; realising the rights of the child to thrive throughout the life-course; facilitating evidence informed policy-making and implementation; and capitalising on interlinkages within the SDGs to galvanise multisectoral action. These five principles offer models that together have the potential of improving design, return and quality of global child health programs while re-energising the 2030 Agenda and the Sustainable Development Goals. [ABSTRACT FROM AUTHOR]

Background: mHealth interventions have huge potential to reach large numbers of people in resource poor settings but have been criticised for lacking theory-driven design and rigorous evaluation. This paper shares the process we developed when developing an awareness raising and behaviour change focused mHealth intervention, through applying behavioural theory to in-depth qualitative research. It addresses an important gap in research regarding the use of theory and formative research to develop an mHealth intervention. Objectives: To develop a theory-driven contextually relevant mHealth intervention aimed at preventing and managing diabetes among the general population in rural Bangladesh. Methods: In-depth formative qualitative research (interviews and focus group discussions) were conducted in rural Faridpur. The data were analysed thematically and enablers and barriers to behaviour change related to lifestyle and the prevention of and management of diabetes were identified. In addition to the COM-B (Capability, Opportunity, Motivation-Behaviour) model of behaviour change we selected the Transtheoretical Domains Framework (TDF) to be applied to the formative research in order to guide the development of the intervention. Results: A six step-process was developed to outline the content of voice messages drawing on in-depth qualitative research and COM-B and TDF models. A table to inform voice messages was developed and acted as a guide to scriptwriters in the production of the messages. Conclusions: In order to respond to the local needs of a community in Bangladesh, a process of formative research, drawing on behavioural theory helped in the development of awareness-raising and behaviour change mHealth messages through helping us to conceptualise and understand behaviour (for example by categorising behaviour into specific domains) and subsequently identify specific behavioural strategies to target the behaviour. [ABSTRACT FROM AUTHOR]

Substance/drug abuse poses a significant threat to the health and socio-economic fabric of individuals and nations. The combined abuse of alcohol and the highly addictive methamphetamine has worsened the drug epidemic in South Africa, especially in the Western Cape province. In this paper, a mathematical model is formulated to model the dynamics of alcohol and methamphetamine co-abuse. We prove that the equilibria of the submodels are locally and globally asymptotically stable when the sub-model threshold parameters are less than unity. The basic reproduction number due to co-abuse is shown to be the maximum of the two sub-model reproduction numbers. Sensitivity analysis reveals that the most sensitive parameters in the co-abuse epidemic are the alcohol and methamphetamine recruitment rates β1 and β2 respectively. The prevalence curve is indicative of a persistent drug problem in the region. Hence, the need to promote social programs that raise awareness of the dangers posed by multiple substance abuse, through educational campaigns in learning institutions, social media and health institutions. Transmission control must focus on enhancing the quitting process while promoting support services to drug users during and after treatment to minimize cases of relapse. [ABSTRACT FROM AUTHOR]

In this paper, a set of local energetic indices for an urban water distribution system is proposed, together with a mathematical organization of the matter which is also able to incorporate many of the well known (global) indicators. In fact, arranged such incoming indices in vectors and drawing on some notions of linear algebra and vector calculus, they are placed at the starting point of a mathematical framework that seems never used before for engineering-hydraulic purposes. It is then told how such a study and local treatment of a water network can be very useful, accurate and rich in information, and can be considered as a natural and simple theoretical development of a common global vision generally pursued so far: in particular, it is shown how it is possible to recover from the drawn layout, through suitable formulas, some of the most known and mainly used energetic parameters in a very clear and effective way. [ABSTRACT FROM AUTHOR]