Two-tier Systems Research Articles

The roads to managed competition for mixed public-private health systems: a conceptual framework.

Health systems' insurance/funding can be organised in several ways. Some countries have adopted systems with a mixture of public-private involvement (e.g. Australia, Chile, Ireland, South Africa, New Zealand) which creates two-tier health systems, allowing consumers (groups) to have preferential access to the basic standard of care (e.g. skipping waiting times). The degree to which efficiency and equity are achieved in these types of systems is questioned. In this paper, we consider integration of the two tiers by means of a managed competition model, which underpins Social Health Insurance (SHI) systems. We elaborate a two-part conceptual framework, where, first, we review and update the existing pre-requisites for the model of managed competition to fit a broader definition of health systems, and second, we typologise possible roadmaps to achieve that model in terms of the insurance function, and focus on the consequences on providers and governance/stewardship.

A clustering-routing approach for assigning customers to depots in last mile delivery

The distribution of goods in crowded city centres is a major challenge today. To address this problem, two-tier or multi-tier distribution systems have been proposed to consolidate parcels flow in intermediary depots such as for instance urban consolidation centres (UCCs). In this paper, we focus on both assigning customers to depots and evaluating the impact of depots’ location. To address these problems, we propose a two-step approach: first, a k-means clustering algorithm is used to group customers’ demand, secondly, a vehicle routing heuristic evaluates the clusters in terms of number of vehicles (i.e. number of routes) and total distance travelled to serve all customers. Experiments are carried out using this approach on real instances of customers’ demand in the city of Bordeaux. Lastly, we analyze the results of the parcels’ distribution in this city centre and compare two situations in terms of vehicle routing: on the one hand, the situation based on existing and operational depots (i.e. real depots) and, on the other hand, the situation exploiting the depots located in the theoretical centre of the clusters (i.e. k-means depots).

Classification and Grading Systems in Gastric Adenocarcinomas.

Gastric adenocarcinomas are lesions that raise important issues in clinical practice, due to their incidence and biological behavior. Over time, various systems have been used for classifying and grading of gastric adenocarcinomas, in the hope of increasing the diagnostic accuracy. In this study we statistically analyzed 112 cases of gastric adenocarcinomas in relation to different classification and grading systems, in order to identify their efficacy and concordance in the histopathological diagnosis. The results indicated a significant association of the Lauren and World Health Organization 2019 classifications and also between these and the three-tier and two-tier grading systems, which supports their practical utility in establishing the diagnosis and assessment of the tumor aggressiveness, for the differentiated therapy.

Loop interchange and tiling for multi-dimensional loops to minimize write operations on NVMs

Non-volatile memory (NVM) is expected to be the second tier of memory in two-tier memory systems. However, because of the limited write endurance, it is vital to reduce the number of writes on NVM. Large-scale nested loops are the performance bottleneck in programs since the data cannot be held on the first tier of memory and then causes many write operations on NVM. Loop tiling groups iterations and loop interchange changes the execution order of the loop to improve data locality and thus reduce communication with NVM. However, research that combines loop interchange and loop tiling for minimizing writes on NVM is uncommon. In this paper, we propose a new loop tiling scheme and combine the loop interchange to solve these issues. Specifically, we propose a strategy to generate the legal tile shape, which is a parallelogram, first. Then, we propose an optimal tile size selection technique to minimize the write operations on NVM. In addition, we adopt the loop interchange technique to help loop tiling generate an optimal tile size for multi-dimensional loops. Finally, we schedule the accessing operations and computations in a pipeline fashion to cover the NVM latency. Experiments show that the proposed scheme can reduce the write on NVM efficiently. In addition, for 2-dimensional loops, NVM latency can be completely hidden.

Do women board members affect dividend policy and cash holdings? Evidence from ASEAN emerging economies

Purpose This study aims to examine the influence of board gender diversity on dividend policy and cash holdings in several emerging economies. This study also investigates the nonlinear impact of women on dividend policy and cash holdings and the differences between countries with one- and two-tier board systems. Design/methodology/approach The sample includes 103 firms listed in the Association of South East Asian Nations (ASEAN) countries of Indonesia, Malaysia, the Philippines and Thailand. The data represent all industries except the financial industry. The sample period is the 10 financial years from 2010 to 2019. This study analyzed unbalanced panel data with fixed effect specifications for baseline model analysis. Findings This study finds robust evidence indicating that women’s presence negatively influences dividends and positively influences cash holdings. The findings in the additional analysis are significant and show a nonlinear relationship, supporting the substitution hypothesis. Practical implications The findings of this paper certainly provided a valuable contribution as a useful empirical guide for policy decision-makers in developing countries, regulators and corporate decision-makers related to board gender diversity. Developed countries have implemented a minimum quota of women boards in the composition of the board of directors. However, there are still few developing countries that implement these policies. Women can reflect or show their values in corporate governance, such as being careful in making decisions and being conservative about risk. These guides policymakers in implementing a minimum quota of women in the composition of the board of directors. Originality/value This study contributes to the debate on the impact of gender diversity on dividends and cash holdings, especially in ASEAN emerging economies because there is a notable empirical gap relative to developed countries. Moreover, this study contributes to the necessary nuanced understanding of the substitution hypothesis in emerging economies. The results also support the explanation of critical mass theory to account for the nonlinear relationship between the number of women board members and dividends and cash holdings.

Examining the limits of the Condorcet Jury Theorem: Tradeoffs in hierarchical information aggregation systems

Condorcet’s Jury Theorem states that the correct outcome is reached in direct majority voting systems with sufficiently large electorates as long as each voter’s independent probability of voting for that outcome is greater than 1/2. Previous research has found that switching to a hierarchical system always leads to an inferior result. Yet, in many situations direct voting is infeasible (e.g., due to high implementation or infrastructure costs), and hierarchical voting may provide a reasonable alternative. This paper examines differences in accuracy rates of hierarchical and direct voting systems for varying group sizes, abstention rates, and voter competences. We derive three main results. First, we prove that indirect two-tier systems differ most from their direct counterparts when group size and number are equal (i.e., when each equals [Formula: see text], where Nd is the total number of voters in the direct system). In multitier systems, we prove that this difference is maximized when group size equals [Formula: see text], where n is the number of hierarchical levels. Second, we show that while direct majority rule always outperforms indirect voting for homogeneous electorates, hierarchical voting gains in accuracy when either the number of groups or the number of individuals within each group increases. Third, we prove that when voter abstention and competency are correlated within groups, hierarchical systems can outperform direct voting. The results have implications beyond voting, including information processing in the brain, collective cognition in animal groups, and information aggregation in machine learning.

Collective bias models in two-tier voting systems and the democracy deficit

We analyse optimal voting weights in two-tier voting systems. In our model, the overall population (or union) is split in groups (or member states) of different sizes. The individuals comprising the overall population constitute the first tier, and the council is the second tier. Each group has a representative in the council that casts votes on their behalf. By ‘optimal weights’, we mean voting weights in the council which minimise the democracy deficit, i.e. the expected deviation of the council vote from a (hypothetical) popular vote.We assume that the voters within each group interact via what we call a local collective bias or common belief (through tradition, common values, strong religious beliefs, etc.). We allow in addition an interaction across group borders via a global bias. Thus, the voting behaviour of each voter depends on the behaviour of all other voters. This correlation may be stronger between voters in the same group, but is in general not zero for voters in different groups.We call the respective voting measure a Collective Bias Model (CBM). The ‘simple CBM’ introduced in Kirsch (2007) and in particular the Impartial Culture and the Impartial Anonymous Culture are special cases of our general model.We compute the optimal weights in the large population limit. Those optimal weights are unique as long as there is no ‘complete’ correlation between the groups. In this case, we obtain optimal weights which are the sum of a common constant equal for all groups and a summand which is proportional to the population of each group. If the correlation between voters in different groups is extremely strong, then the optimal weights are not unique. In fact, in this case, the weights are essentially arbitrary. We also analyse the conditions under which the optimal weights are negative, thus making it impossible to reach the theoretical minimum of the democracy deficit. This is a new aspect of the model owed to the correlation between votes belonging to different groups.

Prognostic significance of tumor budding thresholds in oral tongue squamous cell carcinoma.

Oral tongue squamous cell carcinoma (OTSCC) represents the most common malignancy of the oral cavity. Tumor budding (TB) is a reliable prognostic factor in OTSCC; however, a standardized scoring system is not still validated. The study aims to evaluate the prognostic role of TB in 211 OTSCC patients treated between 1997 and 2018. TB was evaluated on hematoxylin and eosin-stained sections in the hotspot area of the infiltrative front (×200-magnification). It was scored using a two-tier system, a three-tier system, and according to BD-model and revised-Grading system. Univariate and multivariate Cox regression analyses of disease-specific survival (DSS) and disease-free survival (DFS) were performed. A p<0.05 was considered as statistically significant. The two-tier and three-tier systems resulted an independent prognostic factor of DSS. High-risk patients had a 2.21 and 3.08 times increased probability of poor DSS compared with low-risk group. It is significantly increased even for intermediate-risk group. No significant differences emerged classifying patients according to BD-model and revised-Grading system. These data confirm the prognostic value of TB in predicting DSS in OTSCC. Classifying patients into two groups using the 5-bud cutoff significantly discriminates their outcomes. Since the established role of DOI and the poor prognostic value of grading, TB could be considered an independent prognostic marker.

Medicare policies in a two-Tier healthcare system with overtreatment

To alleviate the problem in two-tier healthcare systems in which city hospitals are overutilized while community hospitals are underutilized, some countries (e.g., China) exploit the induction effect of medicare policy and adopt a differentiated medicare policy (DMP) instead of an undifferentiated medicare policy (UDMP). The difference between the two policies lies in the fact that DMP provides no or low reimbursement for patients who directly seek care from city hospitals, while UDMP reimburses all patients at the same rate. However, some countries (e.g., Austria and Japan) have different attitudes toward this approach. To explore the causes of this variation, we examine the impact of medicare policies on service operations in a two-tier healthcare system in which a city hospital can provide services for all kinds of patients but will likely overtreat mildly ill patients, while a community hospital focuses on treating mild illness and refers severely ill patients to a city hospital. Our results indicate that DMP does not always benefit the community hospital and can benefit the city hospital in some cases, which goes against public expectations. Furthermore, DMP may have a counterproductive effect in reducing patient waiting times, but it can outperform UDMP in terms of patient utility and social welfare, even though DMP may cause some patients to suffer financial losses. Interestingly, we find Pareto zones that can yield multi-win outcomes when UDMP is adopted, but these Pareto zones narrow as the reimbursement rate increases.

39 CAN CARE ROBOTS ASSIST OLDER PEOPLE AND LONG-TERM CARE SYSTEMS? KEY STAKEHOLDERS’ PERCEPTIONS IN HONG KONG SAR, CHINA AND IRELAND

Abstract Background Robotics is now seen as part of the solution to the ageing population internationally, and is deployed in care settings. Care robots are designed to enable active ageing as well as ageing in place, with support to older persons, their families, and care professionals. The aim of this study was to understand the perceptions of stakeholders in Hong Kong and Ireland regarding the current state of affairs surrounding the use of care robots in their jurisdictions. Methods Semi-structured, in-depth interviews were conducted with 30 experts (15 from each jurisdiction). The participants included care professionals, service providers, researchers, and advocacy group representatives and policymakers. The questions explored their knowledge of and perceptions regarding the current use of assistive technologies, long-term care systems, and their own future vision of care provision for old age. Results In both jurisdictions, the use of care robots is relatively new, although many respondents were familiar with the seal robot PARO and the humanoid robot Pepper. In Hong Kong, a gerontechnology-specific exposition has become an annual feature in recent years, and the government’s investment has stepped up. In Ireland, a more general ehealth agenda has been adopted within the government’s planned care reform (Sláintecare). Older people in Hong Kong and Ireland are believed to fall through the cracks in their respective two-tier care systems, and many respondents stated that care robots are most needed in order to fill the gaps (e.g. safety monitoring, mobility support). Concerns regarding the impact of using robots included a possible reduction in human-to-human contact and deskilling of older people themselves. Conclusion There was a sense of urgency in both jurisdictions that more smart and digital technologies should be utilised to ease the pressures on care professionals and systems. However, a degree of optimism was noted for technological leapfrogging after the pandemic.

Does a Foreign Board Improve Corporate Social Responsibility?

This study examines the effect of foreign boards on corporate social responsibility, exploring the issues of two-tier board systems (boards of directors and boards of commissioners). Using data for manufacturing firms listed on the Indonesia Stock Exchange over the sample period of 2017–2019, the results suggest that a foreign board engages more in corporate social responsibility activities. Our key finding remains robust with respect to all foreign board measures (foreign ownership, foreign board members, foreign directors, foreign commissioners, foreign CEO, and foreign chairperson) and to alternative estimation methods, and pass a series of endogeneity checks. We established the causal effect from foreign boards to CSR, supporting institutional theory and contesting agency theory.

The Waiting Game - How Cooperation Between Public and Private Hospitals Can Help Reduce Waiting Lists.

Prolonged waiting to access health care is a primary concern for nations aiming for comprehensive effective care, due to its adverse effects on mortality, quality of life, and government approval. Here, we propose two novel bargaining frameworks to reduce waiting lists in two-tier health care systems with local and regional actors. In particular, we assess the impact of 1) trading patients on waiting lists among hospitals, the 2) introduction of the role of private hospitals in capturing unfulfilled demand, and the 3) hospitals’ willingness to share capacity on the system performance. We calibrated our models with 2008–2018 Chilean waiting list data. If hospitals trade unattended patients, our game-theoretic models indicate a potential reduction of waiting lists of up to 37%. However, when private hospitals are introduced into the system, we found a possible reduction of waiting lists of up to 60%. Further analyses revealed a trade-off between diagnosing unserved demand and the additional expense of using private hospitals as a back-up system. In summary, our game-theoretic frameworks of waiting list management in two-tier health systems suggest that public–private cooperation can be an effective mechanism to reduce waiting lists. Further empirical and prospective evaluations are needed.

Gender equality on board and banks’ earning management: Achieving SDG in Southeast Asia’s Corporation

This study aims to analyze the influence of gender equality, which is one issue in sustainable development goals (SDGs), on earnings management of banks in the Philippines, Indonesia, Malaysia, and Thailand stock exchanges. This study uses the Generalized Methods of Moments (GMM) method on 73 listed banks in these countries from 2013-2018. Both linear and non-linear effects of a woman on the board on earnings management are examined in this study, and bank earnings management is measured using discretionary loan loss provisions. This analysis is divided into countries that have one-tier and two-tier corporate governance systems. Our findings suggest that there are insignificant results for the influence of a woman on the board and a woman on the board squared on bank earnings management, measured by discretionary loan loss provision (DLLP), for one-tier and two-tier countries. Meanwhile, there is a different result from previous studies that the presence of three women directors has a significant and positive influence on bank earnings management in two-tier countries. The results of one-tier and two-tier countries can be different because the absolute value of the error term of the two-tier countries is higher than the one of one-tier countries, which indicates higher DLLP values.

Identifying proactive ICU patient admission, transfer and diversion policies in a public-private hospital network

Management of hospital beds is a high-impact issue for two-tier healthcare systems, due principally to their critical importance and high costs. Bed capacity in the public sector is generally insufficient to provide immediate care to all critical patients and thus a significant proportion of public expenditure is assigned to the diversion of patients for treatment in the private sector. We formulate and approximately solve a discounted infinite-horizon Markov Decision Process (MDP) that seeks to identify cost-effective policies for transferring ICU patients between hospitals or diverting them to private clinics. The solution approach employs an affine architecture for approximating the value function of the MDP model and solves the equivalent linear programming model using column generation. The approach can handle a high level of dimensionality, enabling it to consider the arriving patients’ many different diagnostic groups and their corresponding lengths of stay. The decisions generated through this approach often differ from the intuitive ones produced in a typical day-by-day decision process, that does not consider the impact of the current day’s decisions on the future performance of the system. In particular, the resulting policies will in many cases proactively transfer patients to a different public facility or divert them to a private one even though the hospital they first arrived at had beds available. The performance of the proposed method was evaluated by simulating a case study based on data from a hospital network in Santiago, Chile, producing savings of almost 49% due mostly to reduced usage of private services.

Abstract IA08: Improving researcher accessibility to publicly available data through creative integration, geospatial visualization, and open data portals

Abstract The increased accessibility of population-level data made available by the government and public health and consumer agencies provides a unique opportunity for integrative data analysis, spatial visualization with much higher resolution to identify clusters of disease, and their correlation with geospatial, socioeconomic, and demographic predictors. However, interactive mapping and spatial analysis tools are underutilized by health researchers and decision-makers as a result of scarce training materials, few examples demonstrating their successful use, and poor mechanisms for sharing results generated by geovisualization. Further, in the wake of massive amounts of new data and analytical tool availability, consumers of cancer population health data, such as academic researchers and public health practitioners, are facing an ongoing transformation of practice resulting in the need for effective collaboration and sharing of resources within and across disciplinary and geographic boundaries. In this talk we will summarize three of our ongoing projects that leverage web-based technologies with the aim to reduce barriers to data sharing, promote simultaneous analysis of multiple datasets, and enable geovisualization of cancer outcomes and their interrelationships with social and spatial factors. The Disentangling Disparities Data Warehouse, or D3W, is a population-based data resource that includes geotagged California Cancer Registry data linked to census, American Community Survey, and other curated sources of neighborhood-level contextual and environmental data. The D3W allows ecologic and/or multilevel statistical analysis and supports sophisticated analysis of the spatial dynamics of cancer in California. The HealthWebMapper is a highly interactive data visualization tool with a simple two-tier web geographic information systems (GIS) framework. This dynamic web GIS/mapping tool was created with open-source JavaScript library, Leaflet, and free web authoring tools (bootstrap, jquery, and Google Chart) to provide user-friendly maps and data-mining functions, including multiple classification methods, correlation analysis, data export, and side-by-side displays. HealthWebMapper is an open source application and available via a public Github repository, and it can be easily installed on any website without specialized GIS servers or databases. Finally, to promote ease of access to the D3W and HealthWebMapper as well as other research data resources, we are developing the Health Data Open Analytic Portal, with support from the newly established NIH-funded HealthLINK Center for Population Health and Health Disparities Research at San Diego State University. The key functions of the open data portal are to archive, manage, download, and integrate disease, environmental, socioeconomic, and health behavior data. The data portal will enable the sharing, archiving, and learning of research procedures and health data resources. The searchable and downloadable data portal will also provide comprehensive research investigator profiles and online training materials to facilitate transdisciplinary research collaborations in cancer population health and beyond. Citation Format: Caroline A. Thompson, Ming-Hsiang Tsou. Improving researcher accessibility to publicly available data through creative integration, geospatial visualization, and open data portals [abstract]. In: Proceedings of the AACR Special Conference on Modernizing Population Sciences in the Digital Age; 2019 Feb 19-22; San Diego, CA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2020;29(9 Suppl):Abstract nr IA08.

Information and pricing effects in two-tier public service systems

Public services such as healthcare may be offered by both free and toll service providers. Such a system, called a two-tier service system, is usually subject to congestion and often modeled as two parallel queues. Customers can choose one of three options: joining the free system, joining the toll system, or balking based on the congestion level in each service system and the toll price. This study examines the joint effects of delay information and the price of the toll system on system performance. We consider the performance measures from three different perspectives: the customers, toll service providers, and social planners. Two information scenarios are studied. In the first scenario, called a mixed information case, the free system does not offer real-time queue length information, contrary to the toll system. In the second scenario, called a non-real-time information case, neither system offers real-time queue length information. Because the system dynamics are highly complex, we propose a computational approach to analyze system performance based on Markovian queueing models. Numerical illustrations are presented to generate important managerial insights for decision-makers An important finding is that there are interaction effects of disclosing delay information and pricing toll service on customer equilibrium strategies and major performance measures of the system. To reduce the expected waiting time, the queue length information should be hidden for lower toll price range and should be disclosed for higher price range. It is also found that the revenue maximization price is different from the socially optimal price.

Interrater variation of vascular classifications used in enhanced laryngeal contact endoscopy.

Combined use of contact endoscopy (CE) and Narrow Band Imaging (NBI, Olympus®) is suggested for the visualization of specific vascular changes indicative of glottic neoplasia. We investigated the interrater reliability and agreement in 3 recognized classification systems of vascular changes applied to images from CE + NBI in patients suspected for glottic neoplasia. Six experienced head and neck surgeons familiar with NBI rated 120 images obtained by CE + NBI by 3 classification systems of vascular changes as suggested by Ni et al. (N-C), Puxeddu et al. (P-C), and the European Laryngological Society (ELS-C). Three raters were experienced in CE, and three raters had only limited experience with CE. Crude agreement and Fleiss' kappa with 95% confidence interval were estimated for all 6 raters, and for the 2 levels of expertise for each original classification system and for dichotomized versions of the N-C and the P-C based on suggested neoplastic potential. The interrater crude agreement and the corresponding kappa values for the ELS-C were good and significantly higher than those for the N-C and P-C for all raters, irrespective of the level of experience with CE (p < 0.0001). There were no significant differences between the N-C and the P-C (p = 0.16). Kappa was considerably improved for both the N-C and the P-C to a level not different from the ELS-C (p = 0.21-0.71) when their 5 original categories were pooled into dichotomized classifications. Difficulties in reliably classifying vascular changes in CE + NBI are evident. Two-tier classification systems are the most reliable.

Monitor or Advise? How Family Involvement Affects Supervisory Board Roles in Family Firms

This paper examines how the involvement of family members in family firms affects the roles of supervisory boards in two-tier board systems. Taking an agency and resource-based perspective, we argue that the occurrence of monitoring and advisory tasks of the board depends on the entanglement of family management and family ownership. This entanglement creates special governance requirements for family firms in two-tier board systems. We use a unique dataset of 186 German family firm observations to show that family involvement in management as well as a high family ownership reduces the occurrence of the monitoring tasks that the supervisory board performs. Moreover, we show that a growing number of owning family branches increases the monitoring tasks. We also provide evidence that family involvement increases the occurrence of the advisory tasks in relation to the monitoring ones.

Hospital referral and capacity strategies in the two-tier healthcare systems

Healthcare referral has been widely advocated and adopted through the implementation of the two-tier healthcare systems whereby patients are transferred from a comprehensive hospital provider (CHP) to a primary hospital provider (PHP). However, operationally, exactly how to implement the healthcare referral program remains a challenging research question, especially when considering the possibility of patient revisits and the coordination needed between the CHP and PHP. To address such a challenge, this paper considers the two-tier healthcare systems consisting of a CHP and a PHP. By establishing a three-stage Stackelberg game within a queuing framework among the CHP, the PHP, and their patients, we first investigate the equilibrium strategy in terms of the CHP's referral rate and the PHP's capacity level, and then examine the impact of revisit rates and referral payments (RP) on the healthcare system and the equilibrium outcomes (e.g., expected utility, social welfare, and waiting times). Two major findings of our study are: (1) both the equilibrium referral rate and the equilibrium capacity first increase and then decrease according to the revisit rate; in addition, the patient referral process always improves the PHP's performance but is likely to sacrifice the social welfare of the CHP. (2) There exists an RP threshold value such that if the RP is below the threshold, then all the permitted patients should be referred and the system performance will be enhanced, in which case a win-win situation in terms of expected utilities can be attained that benefits all the stakeholders, i.e., the CHP, the PHP, and the patients. Otherwise, only a portion of the permitted patients can be referred, and an increase in RP always reduces the efficiency of the healthcare delivery system, i.e., a higher RP mitigates the operational performance of the healthcare system. Our analysis sheds light on how to implement a healthcare referral scheme.

A classification of two-tier distribution systems based on mobile depots

Urban freight transport is an important enabling factor for economic growth and social activities in cities but despite its benefits, it also generates important negative externalities including traffic congestion, pollution, noise and overall less safety. Moreover, increased limitations on urban freight transport, including access constraints, limited kerbside and private parking spaces for loading/unloading, and the often prohibitive costs of installing logistics infrastructures in city centres, have further constrained urban freight transport. To address these issues, several city logistics solutions have been proposed, such as two-tier distribution systems and distribution systems based on mobile depots.In this paper, we focus on two-tier urban freight distribution systems based on mobile depots, where little or no physical infrastructure is considered and where storage is not permitted at transfer locations. In these types of systems, coordination and synchronisation between vehicles are essential, and the main objective is to have vehicles at the transfer locations in a need-to-be basis as a way of minimising the negative externalities.We review and analyse 13 cases found in the scientific literature, trial reports and online resources, and propose a classification of these systems based on the level of mobility and accessibility of transportation modes operating at the first-tier. Furthermore, we characterise the main components and operational features of the different systems, including the existence of multi-trips, the types of transport modes used at both tiers, transported loads and the organisation of the transfer sites (satellites). This work aims to contribute for a clearer characterisation of two-tier urban distribution systems based on mobile depots, to later support the development of the most adequate mathematical models and solution methods to be applied to each variant of this type of systems.