Different Types Of Delays Research Articles

Exploring Delays in Cardiac Care Processes Through Electronic Health Records.

Cardiovascular diseases are the leading cause of death globally. Timely health services are fundamental to the appropriate prevention, identification, care and rehabilitation of these diseases. This study aimed to explore the potential of using electronic health records as a data source to help identify health system -related delays in care processes of cardiac patients. This retrospective registry study is based on a sample of electronic health records of 200 cardiac patients admitted to one out of twenty wellbeing services counties in Finland during the years 2021-2022. A total of 426 health system -related delays were identified. All expressions were found in unstructured format and most of these (58.7%) were generated by nurses. These results show that the electronic health records contained a variety of information on health system -related patient care delays, and that most delays were associated with difficulties in finding a bed for the patient in a post-acute care facility (49.8%), but also in-hospital process delays were common (27.7%). These findings show great potential for exploring electronic health record data with natural language processing methods in the future for the development of tools to better identify and monitor different types of delays in care processes. Such tools may support leadership to respond to organisational procedures in need of improvement.

Stability and synchronization of octonion-valued neural networks with leakage and mixed delays on time scales

There has been a great deal of interest in the last few years for neural networks (NNs) with values in multidimensional domains. The most popular models are complex-valued neural networks (CVNNs), followed by quaternion-valued neural networks (QVNNs), and, more recently, by Clifford-valued neural networks (ClVNNs). However, also very recently, a different type of NNs were put forward, namely octonion-valued neural networks (OVNNs). OVNNs are defined on the 8D octonion algebra, and they are not a special type of ClVNNs, because Clifford numbers are associative, whereas octonions are not. Moreover, beside the complex and quaternion algebras, the only other normed division algebra over the reals is the algebra of octonions, which makes OVNNs a direct generalization of CVNNs and QVNNs from this point of view, raising interest for applications handling high-dimensional data. On the other hand, systems defined on time scales were proposed as a generalization of both discrete time and continuous time systems, or any type of hybrid combination between the two. Finally, time delays appear as a consequence of implementing NNs in real life circuits. Taking all these into consideration, this paper studies the fundamental properties of exponential stability and exponential synchronization for OVNNs with leakage and mixed delays defined on time scales. In order to avoid the problems raised by the non-associativity of the octonion algebra, the OVNN model is decomposed into a real-valued one. Then, two different Lyapunov-type functionals are defined and the particularities of time scale calculus are used in order to deduce sufficient conditions expressed as scalar and linear matrix inequalities (LMIs) for the exponential stability of the proposed models, based on Halanay-type inequalities suitable for time scale systems. Afterwards, a state feedback controller is used to deduce sufficient criteria given as scalar inequalities and LMIs for the exponential synchronization of the same type of models. The generality of the model, given by the definition on the algebra of octonions, the use of different types of delays, and the definition on time scales represent an important advantage. Also, for less general models, it is possible to particularize the obtained results. With the aim to demonstrate each of the paper’s four theorems, four numerical examples are provided.

Improved adaptive micro-grid over current protection scheme considering false tripping

Abstract Adaptive protection is an efficient way to tackle the changing topologies in distribution grids caused by the penetration of renewable energy sources. Effective operation of an adaptive protection scheme requires a fast and reliable communication network. However, inherent time delays can adversely impact the effectiveness of Adaptive Protection Schemes (APSs). This manuscript classifies delays into two types and proposes a method or each type to overcome the effects caused by the corresponding type of delay with an improved APS algorithm. The algorithm uses a combination of centralized and decentralized signaling to counter different types of delays. The improved algorithm is tested on a Canadian 9 bus urban benchmark distribution network. MATLAB Simulink environment is used to simulate the 9 bus benchmark distribution network. The results obtained are demonstrated with the improved scheme on stated test system.

Exploring Dynamics and Hopf Bifurcation of a Fractional-Order Bertrand Duopoly Game Model Incorporating Both Nonidentical Time Delays

In order to maximize benefits, oligopolistic competition often occurs in contemporary society. Establishing the mathematical models to reveal the law of market competition has become a vital topic. In the current study, on the basis of the earlier publications, we propose a new fractional-order Bertrand duopoly game model incorporating both nonidentical time delays. The dynamics involving existence and uniqueness, non-negativeness, and boundedness of solution to the considered fractional-order Bertrand duopoly game model are systematacially analyzed via the Banach fixed point theorem, mathematical analysis technique, and construction of an appropriate function. Making use of different delays as bifurcation parameters, several sets of new stability and bifurcation conditions ensuring the stability and the creation of Hopf bifurcation of the established fractional-order Bertrand duopoly game model are acquired. By virtue of a proper definite function, we set up a new sufficient condition that ensures globally asymptotically stability of the considered fractional-order Bertrand duopoly game model. The work reveals the impact of different types of delays on the stability and Hopf bifurcation of the proposed fractional-order Bertrand duopoly game model. The study shows that we can adjust the delay to achieve price balance of different products. To confirm the validity of the derived criteria, we put computer simulation into effect. The derived conclusions in this article are wholly new and have great theoretical value in administering companies.

Neutral-type, leakage, and mixed delays in fractional-order neural networks: asymptotic synchronization analysis

<abstract><p>The dynamics of fractional-order neural networks (FONNs) are challenging to study, since the traditional Lyapunov theory does not apply to them. Instead, Halanay-type lemmas are used to create sufficient criteria for specific dynamic properties of FONNs. The application of these lemmas, however, typically leads to conservative criteria. The Halanay-type lemma is used in a novel way in this study to develop less conservative sufficient conditions in terms of linear matrix inequalities (LMIs) for extremely general FONNs, with different types of delays, such as neutral-type, leakage, time-varying, and distributed delays. The formulation of such a general model for the fractional-order scenario is done here for the first time. In addition, a new Lyapunov-like function is established, resulting in algebraic conditions that are less conservative. Three theorems are put forward that build sufficient criteria for the asymptotic synchronization, employing state feedback control, of the proposed networks, each based on a different Lyapunov-like function. For the first time in the context of FONNs, the free weighting matrix technique is also used to greatly decrease the conservatism of the obtained sufficient conditions. One numerical simulation illustrates each of the three theorems.</p></abstract>

Exponential stability of discrete-time systems with slowly time-varying delays

Slowly time-varying delays are seldom, but do need to be, considered in the context of discrete-time systems. This paper addresses the exponential stability issue of discrete-time systems with slowly time-varying delays. The basic idea is to transform, by utilizing the switching transformation approach, the original system with slowly time-varying delays into an equivalent switched system with special switching signal. Different types of delays correspond to different types of switching signals, and the stability issue of the original system is converted into that of a switched system. It is the first time that the method of switched homogeneous polynomial Lyapunov function is applied to general delayed systems. Some sufficient exponential stability conditions for the original system are proposed in several situations. It is numerically shown that the conservativeness of the proposed conditions reduces as the degree of the switched homogeneous polynomial Lyapunov function increases.

Periodic Oscillatory Phenomenon in Fractional-Order Neural Networks Involving Different Types of Delays

This research is chiefly concerned with the stability and Hopf bifurcation for newly established fractional-order neural networks involving different types of delays. By means of an appropriate variable substitution, equivalent fractional-order neural network systems involving one delay are built. By discussing the distribution of roots of the characteristic equation of the established fractional-order neural network systems and selecting the delay as bifurcation parameter, a novel delay-independent bifurcation condition is derived. The investigation verifies that the delay is a significant parameter which has an important influence on stability nature and Hopf bifurcation behavior of neural network systems. The computer simulation plots and bifurcation graphs effectively illustrate the reasonableness of the theoretical fruits.

Stability Analysis of a Fractional-Order SEIR-KS Computer Virus-Spreading Model with Two Delays

In this paper, the stability and Hopf bifurcation of a fractional-order model of the Susceptible-Exposed-Infected-Kill Signals Recovered (SEIR-KS) computer virus with two delays are studied. The sufficient conditions for solving the stability and the occurrence of Hopf bifurcation of the system are established by using Laplace transform, stability theory, and Hopf bifurcation theorem of fractional-order differential systems. The research shows that time delays and fractional order q have an important effect on the stability and the emergence of Hopf bifurcation of the fractional computer virus model. In addition, the validity of the theoretical analysis is verified by selecting appropriate system parameters for numerical simulation and the biological correlation of the equilibrium point is discussed. The results show that the bifurcation point of the model increases with the decrease in the model fractional order q. Under the same fractional order q, the effects of different types of delays on bifurcation points are obviously different.

Delay Propagation in Large Railway Networks with Data-Driven Bayesian Modeling

Reliability and punctuality are the key evaluation criteria in railway service for both passengers and operators. Delays spanning over spatial and temporal dimensions significantly affect the reliability and punctuality level of train operation. The optimization of capacity utilization and timetable design requires the prediction of the reliability and punctuality level of train operations, which is determined by train delays and delay propagation. To predict the punctuality level of train operations, the distributions of arrival and departure delays must be estimated as realistically as possible by taking into account the complex railway network structure and different types of delays caused by route conflict and connected trips. This paper aims to predict the propagation of delays on the railway network in the Greater Sydney area by developing a conditional Bayesian model. In the model, the propagation satisfies the Markov property if one can predict future delay propagation in the network based solely on its present state just as well as one could knowing the process’s full history, so that it is independent of such historical procedures. Meanwhile, we consider the throughput estimation for the cases of delay caused by interchange line conflicts and train connection in this model. To the best of the authors’ knowledge, this is the first work of data-driven delay propagation modeling that examines both spatial and temporal dimensions under four different scenarios for railway networks. Implementation on real-world railway network operation data shows the feasibility and accuracy of the proposed model compared with traditional probability models.

Delays in Diagnosis of Cervical Cancer Among Women Attending Tertiary Care Cancer Diagnostic Hospitals in Bhubaneswar, India

Cervical cancer is one of the major causes of cancer deaths among women worldwide, with > 85% of the global burden of these cases and deaths occurring in developing countries. Delay in diagnosis of cervical cancer negatively impacts the prognosis and quality of life. The purpose of the study was to assess the different types of delays in cervical cancer diagnosis and identify the factors associated with the diagnostic delays. This cross-sectional study was undertaken in tertiary care cancer diagnostic hospitals of Bhubaneswar, the capital city of state Odisha during February–June 2018 including 122 women diagnosed with cervical cancer by histopathological examination. The mean age of the study respondents was 52.1 ± 10.9 years. The median total diagnostic delay was 68 days, and 48 (39.3%) patients had delayed diagnosis of cervical cancer. Among all the components, patient delay was the major contributor to the diagnostic delay. Multivariable analysis revealed that variables like lower education status of husband, patient’s positive history of sexually transmitted disease, non-attendance of screening program and not performing cervical/per speculum examination during initial consultation were significantly associated with longer diagnostic delays. There is an urgent need to shorten the diagnostic journey of the cervical cancer patients by addressing all the components of diagnostic delay and developing strategies to modify the factors associated with these delays.

Real-time energy-saving metro train rescheduling with primary delay identification.

This paper aims to reschedule online metro trains in delay scenarios. A graph representation and a mixed integer programming model are proposed to formulate the optimization problem. The solution approach is a two-stage optimization method. In the first stage, based on a proposed train state graph and system analysis, the primary and flow-on delays are specifically analyzed and identified with a critical path algorithm. For the second stage a hybrid genetic algorithm is designed to optimize the schedule, with the delay identification results as input. Then, based on the infrastructure data of Beijing Subway Line 4 of China, case studies are presented to demonstrate the effectiveness and efficiency of the solution approach. The results show that the algorithm can quickly and accurately identify primary delays among different types of delays. The economic cost of energy consumption and total delay is considerably reduced (by more than 10% in each case). The computation time of the Hybrid-GA is low enough for rescheduling online. Sensitivity analyses further demonstrate that the proposed approach can be used as a decision-making support tool for operators.

Stability Analysis of SIR Model with Distributed Delay on Complex Networks.

In this paper, by taking full consideration of distributed delay, demographics and contact heterogeneity of the individuals, we present a detailed analytical study of the Susceptible-Infected-Removed (SIR) epidemic model on complex population networks. The basic reproduction number of the model is dominated by the topology of the underlying network, the properties of individuals which include birth rate, death rate, removed rate and infected rate, and continuously distributed time delay. By constructing suitable Lyapunov functional and employing Kirchhoff’s matrix tree theorem, we investigate the globally asymptotical stability of the disease-free and endemic equilibrium points. Specifically, the system shows threshold behaviors: if , then the disease-free equilibrium is globally asymptotically stable, otherwise the endemic equilibrium is globally asymptotically stable. Furthermore, the obtained results show that SIR models with different types of delays have different converge time in the process of contagion: if , then the system with distributed time delay stabilizes fastest; while , the system with distributed time delay converges most slowly. The validness and effectiveness of these results are demonstrated through numerical simulations.

Supply chain integration in the South African conveyancing environment

Background: Although conveyancing is a legal term, business management and specifically operations management principles also apply to the processes involved in conveyancing. From a business perspective, each organisation is usually concerned with its own profit margins and processes. In our global market, however, organisations now realise that they can no longer compete successfully on the basis of their internal operational efficiencies alone. They are therefore constantly aware of the need to improve not only their internal processes but also their alignment with other supply chain linkages in an effort to optimise the performance of the whole supply chain. Such alignment, in the conveyancing environment, includes government departments that are generally less willing to adopt business principles, which in turn makes optimisation of the whole supply chain more difficult.Objectives: The article describes a supply chain perspective of the conveyancing processes in South Africa and reports some of the factors that influence and delay conveyancing transactions. It explores possibilities of collaborative relationships between different role players in the conveyancing supply chain. It aims to show that a supply chain approach, as opposed to a singular organisational approach, can help to reduce process bottlenecks and delays in order to improve overall process efficiency.Method: The research, on which the findings are based, was exploratory in nature and followed a mixed-methods (quantitative or qualitative) approach and included both structured questionnaires and personal interviews.Results: The results of the study revealed that many different types of delays occur at various entities across the whole supply chain involved in property transfers. These delays are presented in a table and diagram.Conclusion: It is recommended that greater adoption of electronic technology across the whole supply chain would improve overall efficiency, eliminate bottlenecks and contribute towards efforts to optimise the conveyancing supply chain in South Africa. In addition, it is also recommended that the South African deeds registry implement an electronic system which would allow for the electronic lodging of property transfers.Keywords: e-conveyancing; electronic processes; digitisation of data; supply chain management; integration

Bifurcation analysis of macrophages infection model with delayed immune response

Macrophages are capable of producing large amounts of both intracellular and extracellular infected cells without necessarily succumbing to the lethal effects of productive viral infection. In this manuscript, authors studied the macrophages infection by human immunodeficiency virus type 1 in the form of mathematical models along with two different types of delays. The asymptotic stability of the constructed model without time delay is proved by utilizing the roots of the characteristic quasi-polynomial which is obtained by applying Jacobian matrix method. Based on Routh–Hurwitz criterion, the dynamical properties of model with a delay is investigated. Instead of discrete time delay, the effect of distribution of delays in the immune activation is also analyzed by using linear chain trick technique. In particular, the model undergoes Hopf bifurcation depending on the critical value of single delay in the activation of immune response. Anti-retroviral treatments have been used to control the replication of HIV-1 virus in infected patients is investigated along with time delay. Moreover, it is proved that the existence of two different types of delays may cause the solutions of the model to become stable or unstable depending on the conditions of chosen bifurcation parameter. Numerical simulations are performed to validate the derived theoretical results.

Mathematical analysis of a model for thymus infection with discrete and distributed delays

In this paper, the dynamics of mathematical model for infection of thymus gland by HIV-1 is analyzed by applying some perturbation through two different types of delays such as in terms of Hopf bifurcation analysis. Further, the conditions for the existence of Hopf bifurcation are derived by evaluating the characteristic equation. The direction of Hopf bifurcation and stability of bifurcating periodic solutions are determined by employing the center manifold theorem and normal form method. Finally, some of the numerical simulations are carried out to validate the derived theoretical results and main conclusions are included.

Delays in receiving obstetric care and poor maternal outcomes: results from a national multicentre cross-sectional study.

BackgroundThe vast majority of maternal deaths in low-and middle-income countries are preventable. Delay in obtaining access to appropriate health care is a fairly common problem which can be improved. The objective of this study was to explore the association between delay in providing obstetric health care and severe maternal morbidity/death.MethodsThis was a multicentre cross-sectional study, involving 27 referral obstetric facilities in all Brazilian regions between 2009 and 2010. All women admitted to the hospital with a pregnancy-related cause were screened, searching for potentially life-threatening conditions (PLTC), maternal death (MD) and maternal near-miss (MNM) cases, according to the WHO criteria. Data on delays were collected by medical chart review and interview with the medical staff. The prevalence of the three different types of delays was estimated according to the level of care and outcome of the complication. For factors associated with any delay, the PR and 95%CI controlled for cluster design were estimated.ResultsA total of 82,144 live births were screened, with 9,555 PLTC, MNM or MD cases prospectively identified. Overall, any type of delay was observed in 53.8% of cases; delay related to user factors was observed in 10.2%, 34.6% of delays were related to health service accessibility and 25.7% were related to quality of medical care. The occurrence of any delay was associated with increasing severity of maternal outcome: 52% in PLTC, 68.4% in MNM and 84.1% in MD.ConclusionsAlthough this was not a population-based study and the results could not be generalized, there was a very clear and significant association between frequency of delay and severity of outcome, suggesting that timely and proper management are related to survival.

A Comparison of Stochastic Systems with Different Types of Delays

In this article, we investigate the effects of different types of delays, a fixed delay and a random delay, on the dynamics of stochastic systems as well as their relationship with each other in the context of a just-in-time network model. The specific example on which we focus is a pork production network model. We numerically explore the corresponding deterministic approximations for the stochastic systems with these two different types of delays. Numerical results reveal that the agreement of stochastic systems with fixed and random delays depend on the population size and the variance of the random delay, even when the mean value of the random delay is chosen the same as the value of the fixed delay. When the variance of the random delay is sufficiently small, the histograms of state solutions to the stochastic system with a random delay are similar to those of the stochastic model with a fixed delay regardless of the population size. We also compared the stochastic system with a Gamma distributed random delay to the stochastic system constructed based on the Kurtz's limit theorem from a system of deterministic delay differential equations with a Gamma distributed delay. We found that with the same population size the histogram plots for the solution to the second system appear more dispersed than the corresponding ones obtained for the first case. In addition, we found that there is more agreement between the histograms of these two stochastic systems as the variance of the Gamma distributed random delay decreases.

Stability switches and double Hopf bifurcation in a two-neural network system with multiple delays

Time delay is an inevitable factor in neural networks due to the finite propagation velocity and switching speed. Neural system may lose its stability even for very small delay. In this paper, a two-neural network system with the different types of delays involved in self- and neighbor- connection has been investigated. The local asymptotic stability of the equilibrium point is studied by analyzing the corresponding characteristic equation. It is found that the multiple delays can lead the system dynamic behavior to exhibit stability switches. The delay-dependent stability regions are illustrated in the delay-parameter plane, followed which the double Hopf bifurcation points can be obtained from the intersection points of the first and second Hopf bifurcation, i.e., the corresponding characteristic equation has two pairs of imaginary eigenvalues. Taking the delays as the bifurcation parameters, the classification and bifurcation sets are obtained in terms of the central manifold reduction and normal form method. The dynamical behavior of system may exhibit the quasi-periodic solutions due to the Neimark- Sacker bifurcation. Finally, numerical simulations are made to verify the theoretical results.

Why do GDPs fail to recognise oral cancer? The argument for an oral cancer checklist

Delays in the diagnosis of oral cancer have been the subject of several cases recently reported in the media. Different types of delays include patient delays, doctor delays and system delays. Although diagnostic delays in primary care constitute a minority of these cases they are potentially modifiable and therefore an important aspect of care to address. GDPs need to be aware of several different factors when assessing the risk for oral cancer including the changing epidemiology of oral cancer and new trends in tobacco consumption, for example the increasing use of waterpipes (shishah/hookah). However several problems in fully assessing patients for oral cancer have been reported. These include time constraints, a lack of remuneration and little training in assessing risk factors and conducting a soft tissue examination. This article reviews these issues and puts forward the case for oral cancer detection as a compulsory CPD topic and a national oral cancer checklist as a tool to ensure all aspects of the oral cancer assessment are considered, which can then be audited and remunerated.

Stochastic vs. Deterministic Models for Systems with Delays

We consider population models with nodal delays which result in dynamical systems with delays. For small population models the appropriate models are discrete stochastic systems with delays. We consider these delay systems and present new theoretical and computational results for such systems. In particular, in this note we summarize results on the effects of different types of delays (a fixed delay and a random delay) on the dynamics of stochastic system as well as their relationship with each other in the context of a just-in-time network model. In addition, we numerically explore the corresponding deterministic approximations for the stochastic systems with these two different types of delays.