Contract Model Research Articles

Cost Analysis in the Transition of Projects to Remote Work During the COVID-19 Pandemic

Theoretical Benchmark: The COVID-19 pandemic forced businesses to undergo unprecedented transformations. Projects emerged as key drivers of change, necessitating clear intentions and resource organization. Amid economic challenges, companies globally pivoted to remote work, leading to cost analysis implications. Delays and cost overruns persisted in project management, with factors like inadequate forecasting and unforeseen risks contributing. The study aimed to evaluate the expenses of three consulting projects transitioning from in-person to remote work due to the pandemic's impact. Method: This study employs an exploratory case study methodology to examine the transformations undertaken by a private entity offering educational and technology services in response to the COVID-19 pandemic. The focus is on the technology and innovation sector, where services include metrology, technical services, product development, and consulting. Cost analysis is conducted, comparing in-person and remote project execution, with a fixed-price contract model, and profit margins are evaluated for each project mode. Results and Conclusion: Adapting projects to remote work during the pandemic reduced costs and increased profit margins, with Project A achieving a 4.9% profit margin due to savings. Projects B and C saw significant cost reductions of 17% and 31%, respectively, when executed remotely, leading to higher profit margins. The study underscores the potential for remote consulting projects as a viable business opportunity and suggests further research into their impact on customer satisfaction and pricing competitiveness. Research Implications: The study's findings recommend that consulting firms should adopt standardized cost estimation procedures and implement project-specific cost monitoring. These implications offer practical guidance to consulting firms aiming to excel in demanding situations and streamline their operations effectively. Originality/Value: This research explores how consulting firms can thrive during crises like COVID-19 by adopting remote work, which reduces costs and increases profitability. It suggests, as a topic for future research, a more detailed analysis of the correlation between project execution in-person and remotely, and how this directly affects the satisfaction and performance of client companies.

A two-stage capacity reservation contract model with backup sourcing considering supply side disruptions

ABSTRACT To deal with disruption at the supply side, the use of backup suppliers is among the commonly employed strategies. In this research, we derived a dual sourcing model using capacity reservation contracts for a supply chain consisting of a retailer, a primary supplier who may experience disruption, and a reliable backup supplier. This dual sourcing model is a reactive strategy that balances flexibility and redundancy to improve supply chain resilience. The aim of the proposed model is to help find optimal solutions for the reserved capacities of the retailer to the suppliers and the constructed capacities of the suppliers. It has been derived in this research that the above-mentioned reserved/constructed capacities exist uniquely. Sensitivity analyses were also conducted to examine the impact of contract parameters on decision variables. This research contributes to existing knowledge by providing deeper insights into the application of the capacity reservation contract to handle supply disruption.

Machine learning approach for ion imprinted (IIP) and non-imprinted (NIP) polymer discrimination based on pyrolysis kinetic data

The improper disposal of effluents containing toxic elements, such as nickel and mercury, can result in the gradual deterioration of surface water quality, impacting aquatic ecosystems and human health. Ionically imprinted polymers (IIPs) are promising candidates for remediating toxic areas due to their high removal rates and selectivity. In this study, multifunctional IIPs were developed using Ni2+ and Hg2+ as template ions and dithizone, methacrylic acid, and ethylene glycol dimethacrylate as complexing agent, monomer, and cross-linking agent, respectively, to remove Ni (II) and Hg (II) from effluents. The thermal decomposition behavior and degradation mechanism of ion imprinted polymers were investigated to address the issue of limited lifespan. The kinetic study revealed that the samples showed significant thermal stability, and the IIP-Duo sample exhibited higher activation energy compared to the non-imprinted polymer (NIP) and the mono-imprinted polymer (IIP), indicating that double impression alters the structure of the polymer and consequently its thermal degradation. Three machine learning models were applied to classify the samples according to imprinting, successfully predicting 95% or more of the classes correctly without overfitting or overmodelling. The master plot method showed that imprinting did not affect the thermal decomposition pathway, with the IIP, IIP-Duo, and NIP samples presenting the same mechanism geometrical contraction model (R3) at a conversion rate between 0.4 and 0.9. These findings suggest that multifunctional IIPs are promising materials for remediating areas impacted by toxic elements.

An incentive mechanism contract model to coordinate a vaccine supply chain under demand uncertainty

PurposeThe increasing prevalence of a wide range of infectious diseases, as well as the underwhelming results of vaccination rates that may be traced back to problems with vaccine procurement and distribution, have brought to the fore the importance of vaccine supply chain (VSC) management in recent years. VSC is the cornerstone of effective vaccination; hence, it is crucial to enhance its performance, particularly in low- and middle-income countries where immunization rates are not satisfactory.Design/methodology/approachIn this paper, the authors focus on VSC performance improvement of India by proposing supply contracts under demand uncertainty. The authors propose three contracts – wholesale price (WSP), cost sharing (CS) and incentive mechanism (IM) for the government-operated immunization program of India.FindingsThe authors' findings indicate that IM is capable of coordinating the supply chain, whereas the other two contracts are inefficient for the government. To validate the model, it is applied to a real-world scenario of coronavirus disease 2019 (COVID-19) in India, and the findings show that an IM contract improves the overall efficiency of the system by 23.72%.Originality/valuePrevious studies focused mainly on the influenza VSC industry within developed nations. Nonetheless, there exists a dearth of literature pertaining to the examination of supply contracts and their feasibility for immunization programs that are administered by the government and aimed at optimizing societal benefits. The authors' findings can be beneficial to the immunization program of India to optimize their VSC cost.

Инструментарий контрактного подхода к инвестиционному обеспечению региона

The article presents structural and logical models of infrastructure regional benchmarking and contract modeling of regional investment projects as the main tools for improving the investment provision of the region by creating a high-quality institutional environment for investors.

The Problem with Inventing Molecular Mechanisms to Fit Thermodynamic Equations of Muscle.

Almost every model of muscle contraction in the literature to date is a molecular power stroke model, even though this corpuscular mechanism is opposed by centuries of science, by 85 years of unrefuted evidence that muscle is a thermodynamic system, and by a quarter century of direct observations that the molecular mechanism of muscle contraction is a molecular switch, not a molecular power stroke. An ensemble of molecular switches is a binary mechanical thermodynamic system from which A.V. Hill's muscle force-velocity relationship is directly derived, where Hill's parameter a is the internal force against which unloaded muscle shortens, and Hill's parameter b is the product of the switch displacement, d, and the actin-myosin ATPase rate. Ignoring this model and the centuries of thermodynamics that preceded it, corpuscularians continue to develop molecular power stroke models, adding to their 65-year jumble of "new", "innovative", and "unconventional" molecular mechanisms for Hill's a and b parameters, none of which resemble the underlying physical chemistry. Remarkably, the corpuscularian community holds the thermodynamicist to account for these discrepancies, which, as outlined here, I have done for 25 years. It is long past time for corpuscularians to be held accountable for their mechanisms, which by all accounts have no foundation in science. The stakes are high. Molecular power stroke models are widely used in research and in clinical decision-making and have, for over half a century, muddied our understanding of the inner workings of one of the most efficient and clean-burning machines on the planet. It is problematic that corpuscularians present these models to stakeholders as science when in fact corpuscularians have been actively defending these models against science for decades. The path forward for scientists is to stop baseless rejections of muscle thermodynamics and to begin testing corpuscular and thermodynamic mechanisms with the goal of disproving one or the other of these hypotheses.

A method for detecting tomato canopies’ phenotypic traits based on improved skeleton extraction algorithm

Automatic acquisition of tomato canopies’ phenotypic traits is essential for tomato varieties’ selection and scientific cultivation. Due to the infinite growth characteristics of tomato, its organ development is stochastic and the canopies' internal structure of is also complex. These make it challenging to obtain organs’ detailed phenotypic traits. Thus, this work proposed a method for detecting tomato canopies’ phenotypic traits based on improved skeleton extraction algorithm (ISEA). Firstly, after collecting tomato canopies' point cloud data from multiple perspectives, this work reconstructed its three-dimensional (3D) model accurately. Secondly, the least squares method was used to simplify the spatial contraction model of the Laplace Skeleton Extraction algorithm to obtain the tomatoes’ skeleton point set. On this basic, Greedy algorithm was used to optimise the Edge Collapse algorithm to extract more accurate and reliable skeleton structure. Then, in conjunction with the canopy growth characteristics of the crop and the Intrinsic Shape Signatures (ISS) principle, the simplified skeleton structure was subjected to local principal component analysis (PCA), which achieved the separation of tomatoes’ main stem and leaves. Finally, a modelling algorithm based on Delaunay triangulation was applied to construct the separated organs’ model to calculate phenotypic traits such as stem diameter, leaf area index and average leaf inclination. The calculated results were also compared with the measured values at different growth stages for performance evaluation. The average precision, average recall, average accuracy and micro F1 score of ISEA were 0.9144, 0.7751, 0.7243 and 0.8306, respectively. The overall R2 between calculated values and measured values for stem diameter, leaf area index and average leaf inclination were 0.9638, 0.9067, and 0.9428, and the root mean square errors (RMSE) were 0.3922, 0.0029, and 0.0186, respectively. As a result, the proposed method can extract a simple skeleton from the complex tomato canopy and calculate phenotypic traits accurately. It also provided solid technical support for studying the interaction about “genotype-phenotype-envirotype” in tomato.

The Public Private Partnership Model in the Development and Management of Coal-Fired Power Stations (PLTU) in Jenepoto Regency

Public-private partnership is a form of partnership between the government and the private sector. This study aims to analyze the public-private partnership model adapted to the development and management of coal-fired power stations in Jenoponto Regency, South Sulawesi. The research method uses a qualitative approach to explain research phenomena according to its context. The data sources included primary and secondary data. Data collection consisted of observations, in-depth interviews, and document reviews. The stages of data analysis included data collection, data reduction, data presentation, and conclusion. The results show that the development and management of the Coal-Fired Power Station (PLTU) in Jeneponto Regency uses the lifecycle contract model. The design elements show that the PLTU project consists of two power-generating units. Each unit was designed to deliver a nominal net capacity of not less than 100 MW to the PLN system with a tension of 150 kV. The build element shows that all the PLTU infrastructure and equipments have been built in accordance with the applicable rules and standards. The financing elements of construction and management of the PLTU is the responsibility of the PT. Bosowa Energy assumes responsibility first, followed by PT. PLN Persero will purchase power, while maintenance is a shared responsibility.
 Keywords: public-private partnership, development and management

Comparative Environmental Impacts and Development Benefits of Coastal Aquaculture in Three Tropical Countries: Madagascar, Tanzania and Indonesia.

Aquaculture is still in early development in Madagascar and Tanzania, while in Indonesia, aquaculture has a long history. In Madagascar, villagers are farming seaweed and sea cucumbers, as part of small-scale community-based aquaculture (CBA). They followed a contractual model between a private farming company and farmers. Local non-governmental organisations (NGOs) and public institutions in Madagascar jointly strive to reverse the trend of ongoing anthropogenic coastal degradation. In Tanzania, the cultivation of red seaweeds has been established for over 30 years, with declining production attributed to climate change. While shrimp farming still involves, to some extent, clearing of mangroves in Tanzania, seaweed culture has only mild impact on coastal ecosystems. Farming areas provide shelter and habitat for juvenile fish, crabs and other organisms. Therefore, NGOs ask for support to improve culture methods. Various problems and shortcomings in Indonesia have been clearly identified, including issues related to new aquaculture areas, pollutants, emerging diseases, insufficient broodstock and fry supply, as well as a lack of technology and manpower. To address these challenges and ensure the growth of aquaculture production, the government has implemented national policies and established training and broodstock centers throughout the country. In Madagascar, the CBA programme stands out as a success story and can serve as a template for other coastal regions and countries. In Tanzania, the adoption of CBA model for co-culture could be the future. In Indonesia, due to a very long coastlines and complicated legislation, IMTA seems to be particularly suitable, as successfully tested in model regions.

Improving food security of farming households in Nigeria: Does broiler outgrowers' program make any difference?

The purpose of this research was to examine the impact of outgrowers' programs on the food security of smallholder poultry farming households in Osun State. Using multi-stage sampling technique, a structured questionnaire was designed to collect information from beneficiaries and non-beneficiaries of outgrowers' programs in the study area. Descriptive statistics, food security index, and Heckman's selection model were used to analyze the data. The results revealed that outgrowers and non-outgrowers were on the average, 49 and 45 years old, with about 12 and 8 years of experience in poultry farming, respectively. The Poultry Farmers' Association was represented by 97% of outgrowers and 47% of non-outgrowers. There were four major broiler outgrowers' programs existing in the area. The Anchor-Borrower Outgrowers' program and Osun Broiler Outgrowers' program adopted a fixed contract model, whereas, the Dayntee Farm and GS Farm outgrowers' programs employed a semi-fixed contract model. The incidence of food insecurity was 18% for outgrowers and 35% for non-outgrowers, with food insecurity depth and severity being 0.025 and 0.033 for outgrowers and 0.134 and 0.52 for non-outgrowers, respectively. The study found a significant difference in outgrowers' perceptions of food insecurity as well as their coping strategies. The major perceived indicators of food insecurity were inadequate resource endowment (MD = 0.758, p<0.01) and consumption of low-cost food (MD = 0.0658, p<0.01). Food acquisition on credit (WMS = 1.700), meals adjustment (WMS = 1.425), and cooking methods' modification (WMS = 1.875) strategies were adopted to cope with food insecurity. Participation in the outgrowers' program was influenced by membership of Poultry Farmers' Association, credit access and flock sizes and the significant predictors of food security among the poultry farming households were outgrowers' participation, household size, gender, marital status and credit access. It was therefore inferred that outgrowers were considerably more food secure than the non-outgrowers, encouraging the need to scale up the program in the poultry industry. Introduction of flexible regulations and reproductive education would make the program more rewarding to the poultry farming households.

Особенности расчета начальных (максимальных) цен контрактов при осуществлении государственных закупок

Justification of the initial (maximum) contract price is one of the main tools used at the stage of supplier selec-tion. Establishing the marginal price of the contract has a significant impact on the quality of work performance, qualification of the supplier and, as a consequence, on the efficiency of budget financing utilization as a whole. The aim of the study is to analyze the correctness of the methods used in practice to calculate the initial (maxi-mum) prices of contracts enshrined in the regulatory legal acts of the Russian Federation. Thus, the methods of analysis, synthesis, abduction and comparison of the obtained mathematical calculations were used in the work. The documentation attached to the notices published in the Unified Information System justifying the cal-culation of the marginal price of various contracts has been analyzed. In the course of the analysis, the author calculated the coefficients necessary to decide on the acceptability of the values applied by customers at the stage of supplier selection, in particular, the coefficients of variation and mean square deviation used in the method of comparable market prices. The study identified cases of incorrect application of mathematical justi-fication models in determining the amount of funding aimed at realizing the objectives of budgetary institutions. Such incorrect application of models can lead to an increase in the cost of work and, as a result, the risks of unfair behavior of participants in the contract model.

A blockchain‐based smart contract model for secured energy trading management in smart microgrids

AbstractThe extension of emerging renewable energy sources such as wind and water turbines, solar panels, and the increasing usage of electric vehicles requires the supply and distribution of energy in a small device on local scale and it has created new methods of supplying and selling electricity. Middle buyers and end users can obtain the local energy with the peer‐to‐peer trading method in this large and hierarchical market. This method enables market to manage and exchange the electricity between major suppliers and medium and local levels. Blockchain technology is developing in peer‐to‐peer exchange of electricity and acts as a reliable, efficient, and safe technology in the electricity trading market. In this method, while preserving the privacy of electricity users, by using smart contracts and by removing intermediaries in the energy supply and demand market, direct commercial interactions between energy suppliers and consumers are done. The blockchain technology, while creating trust between the parties in the energy market, reduces the cost of electricity trading and increases its scalability with using the intermediate energy aggregators. In this research, the blockchain‐based model, is presented for distribution and peer‐to‐peer transactions in the energy market. The suggested model provides the possibility of registration low‐cost instant transactions at the power grid in any specific period of time. The above method, unlike periodic payments, provides immediate access to bills and small payments. Since the transactions outside the blockchain chain are not recorded, this system guarantees its honest and independent operation without fraud and failure. The smart contract method based on blockchain, reduces the transaction fees and speeds up electricity trading. Also, the experimental investigation in 20 nodes shows the time required to determine the exchange contract in the blockchain method. The average is improved by 49.7% in this method. Also, the negotiation convergence time has become 47% faster.

Developing Platform Supply Chain Contract Coordination and a Numerical Analysis Considering Fresh-Keeping Services

With changes in demand and the emergence of new distribution channels, consumer-centric buyer’s markets for many products have been formed. The platform supply chain has been continuously optimized and upgraded. Supply chain leaders have moved downstream to the end of the supply chain. The operational value has been further enhanced. The corresponding systematic construction of the platform supply chain has become an important driving force for future development. The model in this paper is different from the traditional supply chain contract model, which mainly focuses on suppliers or demand. In order to meet the requirements of fresh-keeping services and the goal of revenue sharing, we integrate the production and circulation characteristics of fresh produce into the design of a contract model. In this paper, a revenue-sharing contract model of the fresh produce supply chain is constructed based on the core position of retailers, the uncertainty of the market size, and the consideration of a fresh-keeping service. The model is mainly composed of the core retailer and the supplier. Through further numerical analysis, we verify the effectiveness of the revenue-sharing contract model in supply chain coordination. We also analyze the change trends in the optimal retail price, optimal freshness level, and optimal order quantity caused by changes in both the fresh-keeping service capacity and the revenue-sharing coefficient. The results show that after changing these two parameters, the supply chain can achieve coordination under the specified parameter values. The changed parameters will also lead to certain change trends in the optimal retail price, optimal freshness level, and optimal order quantity, and will have a corresponding impact on the stability of supply chain operation. This research provides a relevant theoretical and empirical basis for a fresh produce supply chain contract model with retailers at the core position. We also provide guidance and reference for optimizing the supply chain management mode and improving the overall operational efficiency of the fresh produce supply chain.

Optimal contracting with asymmetric risk aversion information and fairness concerns

PurposeThis study considers a contracting problem between a fairness concerned entrepreneur (EN) and a fair-neutral venture capitalist (VC) to explore the effects of asymmetry, agency conflicts and fairness concerns.Design/methodology/approachThe authors construct the model by assuming the EN's risk aversion degree is private information, which is more realistic but ignored in most studies. Under the principal–agent framework, the authors solve the VC's optimal contracting models by identifying the ranges of feasible solution, where the optimal solutions of these models are explicit and nicely reconcile the “private equity” puzzle. Moreover, validity of the optimal solutions is verified by numerical simulations.FindingsIn accordance with empirical evidence, information asymmetry lowers the optimal equity share that the VC provides to EN but raises EN's profit due to lower effort disutility and information rent. Moreover, the authors find that the fairness concerns is beneficial for the EN, where it not only increases the EN's optimal equity share, but also enhances the certainty equivalence of the EN's utility regarding its profit. Relative to the benchmark model where the EN's risk aversion degree is common knowledge, the EN's efforts recommended by the optimal contract is less sensitive to the EN's fairness concerns degree when the EN does not actually announce its risk aversion degree.Originality/valueFirst, the authors incorporate asymmetry to study a two-period contracting problem and explore how it affects the equity shares allocated to the contractual parties. Second, the authors incorporate fairness concerns and analyze its effect regarding the decision-makings and profits.

Optimal contract design for a supply chain with information asymmetry under dual environmental responsibility constraints

Under dual constraints of green production responsibility and recycling responsibility, the optimal contract between upstream and downstream firms is crucial to achieve low-carbon development, but information asymmetry poses a great challenge to the above contract design. Based on Stackelberg game theory, this paper develops a contract model in a supply chain with information asymmetry under dual environmental responsibility constraints, in which the producer invests in green technology while the retailer exerts green marketing efforts. The paper aims to explore how the producer designs optimal contracts under the different information structures to improve environmental performance while ensuring profitability. Results indicate that: (i) in the full information scenario, the two-part optimal contract makes the decentralized supply chain to achieve the same channel profit and carbon emissions as the centralized scenario. (ii) In the information asymmetry scenario, the producer should design differentiated contract configurations for different types of retailers to eliminate double marginalization. That is, the producer designs low wholesale price and high side payment for the high-type retailer, which enables the producer to earn high profit with low carbon emissions and makes the retailer to obtain additional information profit. While under some conditions, the producer considers the possibility of terminating cooperation with the retailer of low-type, as such a cutoff policy not only guarantees the profitability of the channel members but also improves environmental performance. Furthermore, the impact of some key factors on firms’ decisions, profits, and equilibrium carbon emissions is summarized to guide management decisions.

The Mandatory and Default Regulation in Hungarian Company Law – A Decade of Experience

Abstract 314The option to deviate from a legal provision has been problematic for company law. The theoretical background of legislation is rooted in the interpretative models of company law: the investor model favouring the interests of its members (shareholder theory) and a contractual model which takes into account the stakeholders in the business relationship with the company (stakeholder theory). This article reflects on the development of the regulation’s nature of Hungarian company law; the legislator implemented a fundamental change in the central element to the governance of company law in 2013. After the modification of central regulation concept of Hungarian company law, the role of the judiciary shifted to the classification of the different default-mandatory rules. This article investigates the development of the new company law regulations concept, and the related judicial practice, and also approaches the topic from the view of interests (of creditors, employees and members), striving to create a coherent dogmatic system.

A Kinetic Study on the Preparation of Al-Mn Alloys by Aluminothermic Reduction of Mn3O4 and MnO Powders

The study of aluminothermic reduction in manganese compounds is a complex challenge in preparing Al-Mn alloys. The primary objective of this study was to ascertain the activation energy values for the aluminothermic reduction of MnO and Mn3O4 oxides derived from alkaline batteries. The study melted aluminum found in beverage cans and utilized the technique of powder addition with mechanical agitation. The kinetics of the reaction were studied under the effects of temperature (750, 800, and 850 °C), degree of agitation (200, 250, and 300 rpm), and the initial concentration of magnesium in molten aluminum (1, 2, 3, and 4% by weight). Kinetic measurements for Mn3O4 particles suggest a reaction mechanism that occurs in stages, where manganese undergoes oxidation states [Mn+3] to [Mn+2] until it reaches the oxidation state Mn0, which allows it to dissolve in the molten aluminum, forming alloys with up to 1.5 wt.% of Mn. Therefore, the kinetic of the aluminothermic reduction of MnO is described by the geometric contraction model, while the mechanism of Mn3O4 reduction occurs in two stages: geometric contraction, followed by an additional stage involving the diffusion of chemical species to the boundary layer. In addition, this stage can be considered a competition between the formation of MnO and the chemical reaction itself.

Restriction of the Rights and Coercion of Patients in a Psychiatric Hospital: The Opinion of People With Mental Disorders and Psychiatrists

Objectives: Restriction of the rights of patients in a psychiatric hospital, isolation and fixation, compulsory treatment, and round-the-clock monitoring are negatively perceived by them, contribute to the stigma of a psychiatric hospital, and prevent timely access to psychiatric help We assessed the opinions of patients in psychiatric hospitals and psychiatrists about coercion and violence in the provision of psychiatric care for recommendations on their prevention. Methods: An anonymous survey of psychiatrists and patients was conducted in psychiatric hospitals in three regions. Data were analyzed using descriptive and non-parametric statistical methods. Results: Psychiatrists and patients were positive about the coercive measures in the psychiatric hospital. Physical restraint was considered the prerogative of orderlies by 64.5% of psychiatrists and 35.4% of patients. According to 19.6% of doctors and 28.4% of patients, a psychiatrist can independently apply physical restraint to aggressive patients. Injections of sedative drugs by a psychiatrist personally were considered justified by 81.3% of physicians and 64.6% of patients. Most patients and physicians noted that the psychiatrist needed to be involved in the application of physical restraint to an aggressive patient. Discussion: Psychiatry is currently dominated by an archaic paternalistic model of doctor-patient relations and the delegation of additional functions of social control to psychiatrists. The introduction of a contractual model is required for more effective interaction between the psychiatrist and the patient.

Uncertainty, Investment and Productivity with Relational Contracts

Abstract With relational contracts, increased uncertainty with no change in factor prices is shown to reduce investment in the long run even if the parties are risk-neutral. This contrasts with models based on the impact of financial risk on the cost of capital and on the option value arising from irreversible investment. For the latter, Bloom et al. (Econometrica, 2018) find that a negative first-moment shock, in addition to increased uncertainty, best matches the data. This paper develops a relational contract model to demonstrate the impact of uncertainty on investment, depending on whether investment is general or specific. It then uses a specification calibrated with parameters from Bloom et al. (Econometrica, 2018) to show that this model can generate effects on productivity and investment of the magnitude of the negative aggregate shock in that paper purely with an increase in uncertainty.

A detailed mathematical model of the human atrial cardiomyocyte: integration of electrophysiology and cardiomechanics.

Mechano-electric regulations (MER) play an important role in the maintenance of cardiac performance. Mechano-calcium and mechano-electric feedback (MCF and MEF) pathways adjust the cardiomyocyte contractile force according to mechanical perturbations and affects electro-mechanical coupling. MER integrates all these regulations in one unit resulting in a complex phenomenon. Computational modelling is a useful tool to accelerate the mechanistic understanding of complex experimental phenomena. We have developed a novel model that integrates the MER loop for human atrial cardiomyocytes with proper consideration of feedforward and feedback pathways. The model couples a modified version of the action potential (AP) Koivumäki model with the contraction model by Quarteroni group. The model simulates iso-sarcometric and isometric twitches and the feedback effects on AP and Ca2+-handling. The model showed a biphasic response of Ca2+ transient (CaT) peak to increasing pacing rates and highlights the possible mechanisms involved. The model has shown a shift of the threshold for AP and CaT alternans from 4.6 to 4Hz under post-operative atrial fibrillation, induced by depressed SERCA activity. The alternans incidence was dependent on a chain of mechanisms including RyRs availability time, MCF coupling, CaMKII phosphorylation, and the stretch levels. As a result, the model predicted a 10% slowdown of conduction velocity for a 20% stretch, suggesting a role of stretch in creation of substrate formation for atrial fibrillation. Overall, we conclude that the developed model provides a physiological CaT followed by a physiological twitch. This model can open pathways for the future studies of human atrial electromechanics. KEY POINTS: With the availability of human atrial cellular data, interest in atrial-specific model integration has been enhanced. We have developed a detailed mathematical model of human atrial cardiomyocytes including the mechano-electric regulatory loop. The model has gone through calibration and evaluation phases against a wide collection of available human in-vitro data. The usefulness of the model for analysing clinical problems has been preliminaryly tested by simulating the increased incidence of Ca2+ transient and action potential alternans at high rates in post-operative atrial fibrillation condition. The model determines the possible role of mechano-electric feedback in alternans incidence, which can increase vulnerability to atrial arrhythmias by varying stretch levels. We found that our physiologically accurate description of Ca2+ handling can reproduce many experimental phenomena and can help to gain insights into the underlying pathophysiological mechanisms.