Demand for high-quality surveillance data for malaria, and other diseases, is greater than ever before. In Uganda, the primary source of malaria surveillance data is the Health Management Information System (HMIS). However, HMIS data may be incomplete, inaccurate or delayed. Collaborative improvement (CI) is a quality improvement intervention developed in high-income countries, which has been advocated for low-resource settings. In Kayunga, Uganda, a pilot study of CI was conducted in five public health centres, documenting a positive effect on the quality of HMIS and malaria surveillance data. A qualitative evaluation was conducted concurrently to investigate the mechanisms of effect and unintended consequences of the intervention, aiming to inform future implementation of CI.The study intervention targeted health workers, including brief in-service training, plus CI with ‘plan-do-study-act’ (PDSA) cycles emphasizing self-reflection and group action, periodic learning sessions, and coaching from a CI mentor. Health workers collected data on standard HMIS out-patient registers. The qualitative evaluation (July 2015 to September 2016) included ethnographic observations at each health centre (over 12–14 weeks), in-depth interviews with health workers and stakeholders (n = 20), and focus group discussions with health workers (n = 6).The results suggest that the intervention did facilitate improvement in data quality, but through unexpected mechanisms. The CI intervention was implemented as planned, but the PDSA cycles were driven largely by the CI mentor, not the health workers. In this context, characterized by a rigid hierarchy within the health system of limited culture of self-reflection and inadequate training and supervision, CI became an effective form of high-quality training with frequent supervisory visits. Health workers appeared motivated to improve data collection habits by their loyalty to the CI mentor and the potential for economic benefits, rather than a desire for self-improvement.CI is a promising method of quality improvement and could have a positive impact on malaria surveillance data. However, successful scale-up of CI in similar settings may require deployment of highly skilled mentors. Further research, focusing on the effectiveness of ‘real world’ mentors using robust study designs, will be required to determine whether CI can be translated effectively and sustainably to low-resource settings.The online version contains supplementary material available at 10.1186/s12936-021-03805-z. Transforming malaria surveillance into a core intervention is one of the three pillars of the World Health Organization (WHO) Global Technical Strategy for Malaria 2016–2030), aiming to accelerate progress toward elimination 6–2030, a. In UganMultiple strategies to improve the quality and management of surveillance data have been applied –10. One Although studies suggest that CI is a promising approach for low- and middle-income (LMIC) settings , 14, 17,In 2015–16, a pilot study was conducted to evaluate the effectiveness, feasibility and cost of implementing CI to improve the quality of malaria surveillance data collected in five public health centres in Kayunga, Uganda. The intervention incorporated brief, in-service training on best recording and reporting practices, and CI. Alongside the quantitative evaluation, an interpretive, qualitative study aiming to ‘open the black box’ of CI and address key knowledge gaps was conducted. The aims were: (1) to describe the context in which, and the processes through which, the CI intervention effected change; (2) to identify any factors that support or undermine CI; and, (3) to investigate for any unintended consequences of the CI intervention.The pilot study was conducted in Kayunga District, Uganda, an area of high malaria transmission , which hThe pilot was designed to evaluate the impact of delivering the study intervention at a cohort of health centres over approximately 1 year  register and good data collection practices for all health workers, and a quality improvement intervention that followed the CI methodology. In 2015, prior to the onset of the study, the Uganda Ministry of Health introduced an expanded HMIS OPD register. The new OPD register doubled the amount of data collected, increasing the number of indicators from 14 to 31. The new register captured additional malaria-related data , and demanded the use of technology . For the CI component, health workers were selected from each health centre by a senior member of staff to take part in a CI team, (ranging from 4 to 8 members). The CI team participated in learning sessions and coaching visits and were expected to keep a CI journal during the intervening action period, which constituted the PDSA cycles (Table While meetings with mentors and project staff (the learning sessions and coaching visits) happened periodically and never more than once a month, the overall approach was expected to re-shape daily life in the health facilities. In accordance with the training and the programme, health workers were expected reflect on their practice in journals, to meet regularly to discuss progress around data collection and changes that they had implemented to improve practice. These reflections were then discussed during the coaching visits and learning sessions. At the learning sessions, health workers would also identify new ways to improve data collection in their facilities.The objective of the qualitative research was to provide a rigorous analysis of CI and the practices associated with the intervention. The data was triangulated by drawing on ethnographic observations and informal discussions, in-depth interviews with individual health workers, and focus group discussions (FGDs) to ascertain group interpretations.The ethnographic fieldwork was conducted by the qualitative team of three local social scientists fluent in Luganda, overseen by an anthropologist based overseas who made three visits to Uganda during the study. Ethnographic observations were conducted at each of the five health centres for 12–14 weeks over the 9-month evaluation period. Each social scientist was attached to one (HC IV) or two (HC II and HC III) health centres for the research period. Observations of everyday activities and practices, and CI activities (coaching visits and PDSA cycles), were carried out by the same social scientist throughout the study. HC IIs and HC IIIs were observed for 2 days per week. Observations at the HC IV were carried out for 3–4 days per week.The fieldwork began with unstructured general observations , during Twenty in-depth interviews were conducted by the qualitative team after the ethnographic fieldwork had been completed, including 15 interviews with health workers taking part in the CI teams and 3 with district officials, focusing on data collection and use at the health centres and the CI intervention, and 2 interviews with national stakeholders, focusing on data collection and quality, changes in data collection tools over time, and themes identified in ethnographic observations . Written informed consent was obtained from participants. Interviews were conducted in English, recorded and transcribed verbatim.At baseline, three FGDs were conducted by the qualitative team at an off-site location in Kayunga District with a total of 36 health workers from the five health centres, including senior health workers , middle-ranking clinicians, and lower-ranking staff (data entry clerks). The FGDs were stratified by health-worker cadre and aimed to assess the collection and use of data at the health centres, and how health workers learned about the health situation in the community. Another three FGDs were held with 31 health workers in total to explore health-worker experiences with the CI intervention, and sustainability of the changes made at the health centres. Written informed consent was obtained from all FGD participants. The FGDs were conducted in English, apart from the FGD held with lower-cadre health workers, which was conducted in the local language (Luganda). The FGDs were transcribed and when required, translated into English using a meaning-based approach .The data were analysed using an interpretive, iterative approach which included both theory and data-driven analysis. The fieldwork notes were shared with the senior anthropologist and analysed in an on-going, iterative fashion, and findings from the ethnographic fieldwork were discussed during weekly team meetings. After the observations, the notes were re-analysed thematically by hand. Key findings were mapped in relation to the various elements of CI so that observed changes in practice at the health centres could be associated with elements of CI.The transcripts of the interviews and FGDs were read and reviewed by the social scientists and senior anthropologist as they were completed. Questions in the topic guide were modified if necessary, based on the responses. Transcripts were also coded in Nvivo qualitative data coding software Version 10 , using a mix of pre-defined codes drawn from the ethnographic data and theory but also data-generated themes.The fieldwork was carried out from July 2015 to September 2016  A lot of data is collected there. A lot of data is collected at the centre. There are patient data. We have other data like the infrastructure data, the inventory data, the financial data, yeah. There is patient data from all diseases we see.” .The combination of CI and the new OPD registers led to increased work. To complete the new OPD registers, which were introduced just before the CI intervention and included substantially more variables, health workers were required to expand the patient history, carry out additional tests, use different technologies, and record more data. This occurred in a context in which health workers already bore a heavy data collection burden. As one district official reported:In this context, health workers described the introduction of new procedures for the CI intervention as challenging, adding new pressures to their already busy workdays. The ease of incorporating CI appeared to be influenced by the size of the health centre. In the smaller HC IIs, services are more limited and health workers frequently multitask, taking responsibility for all aspects of patient care, including clinical evaluations, testing  and dispensing medications, as well as completing OPD registers. In these spaces, incorporating CI and improving data collection appeared relatively straightforward. However, in the larger HC IIIs and HC IV, patients travel through more complex pathways, navigating the clinical, laboratory and pharmacy services. Health workers also move through the health centres over the course of the day, shifting tasks and working in different spaces. In these complex settings, introducing CI came with considerable operational changes and substantial modifications had to be made to triage, to the flow of patients through the health centre , to the location of the OPD and other registers, and to the chain of custody for patient books .While the combination of the new OPD register and CI appeared to make considerable demands on the health centre staff, the work involved in collecting data was often considered to have little positive impact on patient care at the health centres. Indeed, some health workers (and their patients) complained that the time patients waited at the health centres extended considerably, negatively impacting on patient satisfaction. That said, over the course of the CI intervention, changes in the perception of the importance of data collection did occur. During the baseline FGDs, health workers were unable to describe the potential uses of the OPD data for their health centre, but during the follow-up interviews with members of the CI teams, data collection was identified as helping health workers to plan, account for medicine use and demonstrate improvements.As the project developed, this sense of the division between everyday care work that health workers undertook and the work involved in completion of the OPD register and CI was also reflected in their identification of CI and its components as belonging to the CI mentor. They often referred to CI as ‘the mentor’s project’, and the CI journal as ‘the mentor’s book’. Health workers also identified data collection and the CI intervention as being necessary and important for research organizations rather than something that supported their work at the health centre. As one health worker argued:“So  has been a good person and he normally calls us when we sit he tells us exactly what we are supposed to do and ideally marry his suggestions because if somebody else comes and does a research here with these registers, they are up to date. Everything is okay, well detailed. They can even follow up somebody, a person who died some time back using these records using the same OPD number until this person went, until the patient got cured or what so that is what  was telling us. And ideally what he has given us it has shown us that in the future we shall also be involved in other researches.” .The CI intervention was dependent upon group work and sharing experiences of changing practices of data collection between health centres. Yet, tensions existed between the health centres around the difficulties the HC IV faced in implementing changes, in contrast with the HC IIs and HC IIIs, which found it easier to improve data collection. During informal discussions, senior members of staff, especially at the HC IV, expressed frustration and some embarrassment that their performance was not better than that of the lower-level health centres, which tended to have less well-trained staff and to offer more basic services. While this could be interpreted as setting up a healthy rivalry that might spur on action, during two learning sessions (sessions 2 and 3) and again in the Harvest Meeting, it seemed to impact negatively on the potential for collaboration. Changes that had proved effective in smaller health centres (HC IIs) were rejected outright as not feasible for larger health centres, without critical reflection. For example, when discussing how to manage personal patient records with the new patient pathways:“One of the health workers from the HC II proposes that the HC IV takes up the method of putting a mark in the patient book to indicate that it [the patient details] have been entered in the OPD register. The senior member of the HC IV team says that they have tried that before, and it didn’t work. [Later in the meeting] the senior member of the HC IV team tells me that the lower health facility health workers are presenting unrealistic scenarios. The laboratory assistant tells me that it is definitely easier to complete registers in the HC IIIs and IIs.“ .Overall, when coupled with the new OPD register, CI was interpreted as creating more work for health workers in a context of existing data collection demands. CI was often interpreted as belonging to the mentor and of benefit to those conducting research, instead of the health centre and its patients and health workers. CI also clashed with the hierarchies that existed between health centres. Health workers in Health Centre IIIs and IVs, who were often more senior members of staff and viewed their more complex services as superior to those in Health Centre IIs were keen to defend their own practice and criticize those of more junior staff. Nonetheless, the project was considered successful in terms of the uptake of the different elements of CI, and its ability to engender change around data collection practices. Below, the construction of this success and how it was incorporated into everyday practice is analysed.The new OPD, nobody trained [us]. They just dumped the book then they said we shall be trained on job. So, that is why for instance when we went for the workshop in Kampala where we scored zero level then we got the ideas after maybe  was telling us how to write in this register because we were not trained. CI was experienced as a high-quality training and supervision. While district health officials had provided training on the new OPD register, many health workers involved in CI reported that they had received little or no training on how to complete the registers. As one health worker described:While some health workers described the in-service training as the most important element of the intervention, for many health workers, the coaching visits seemed to be the key component underpinning change. Health workers described these visits as a form of regular supportive supervision that was otherwise missing in the health system. The mentor, who was very experienced, was highly valued by the health workers; they described him as patient and providing on-going, uncritical support in the face of their daily challenges, and the changes that they sought to make.per diem to those who attended meetings and not to those who were working on the CI and the new OPD in the health centres was raised as an important issue during the ethnographic observations, in-depth interviews and FGDs. Officially, per diem is paid to cover the costs associated with travel to the workshop and staying overnight. Yet, when it is possible to save this money per diem can represent a substantial additional income for health workers, amounting in some instances in this project to around a third of the health worker’s monthly income. The per diem provided during the learning sessions were interpreted as payment for the additional work associated with the intervention, and health workers who had not attended these events (and thus received no payments) described themselves (or were described by members of the CI team) as reluctant to undertake the work. As one FGD participant, who had been a member of a CI team explained, this impacted on the ways in which the intervention was rolled out in the health centres following the learning sessions.your work. [Laughter] ‘Ho batwongedde emirimu’ (we have been given more work) so it has not been easy. But slowly, I hope if we are to maintain it [the project] better, I think if those who remained [i.e. have not attended project meetings] are also called in such meetings [as] we are sitting [now], then talked to, things will go [on for] 100 years and years [Laughter] Mentoring is not easy because some people are so rigid. You tell someone do this, and that person says, aaah after you [have been] eating money [i.e. getting payments from the project] you are here disturbing us with While none of the CI team members reported that the financial benefits had influenced their participation in the intervention, the distribution of your work”), while the key to sustainability of the intervention (its ability to “go on for 100 years”) was described as the inclusion of all health workers, ensuring that all receive the financial benefits. This idea that the per diem was experienced as payment for work associated with CI was also in evidence during the learning sessions. Below, field notes made during the third learning session suggest that the trainers also see the per diem not as recompense for expenses but rather as payment for their active involvement and understanding of CI:Here, the work associated with the intervention was identified as belonging to the health workers who attended the learning session During informal conversations and in-depth interviews, health workers described how, prior to the implementation of the intervention, the responsibility for completing the OPD register was shared amongst multiple health workers, particularly at the larger health centres. Once CI was established with the CI teams, who received training and payments, in the higher-level health centres (HC IIIs and HC IV) new divisions of labour emerged between those who took responsibility for data and those who did not. Health workers outside of the CI team continued to express dissatisfaction with the intervention and frustration with the burden of work presented by the new OPD register. In contrast, many of the members of the CI team became attached to the intervention and expressed loyalty to the project and the CI mentor.While health workers who were not part of the CI team did not champion or push forward improvements in data collection, they were observed to change their practices aiming to improve the completeness of the OPD data. As CI became more embedded in the larger health centres, the additional work involved in improving data quality was also managed by recruiting patients and volunteers to take simple measurements  and to record data in the register. Patients would help with height and weight measurements and village health team members (VHTs) took on a variety of responsibilities that included recording patient details, completing the OPD registers, completing anti-retroviral cards for HIV, triaging patients, screening for tuberculosis, testing for malaria, and dispensing medications.CI is a quality improvement strategy that has been increasingly advocated for, and applied in, low-resource settings. In this pilot study, CI was applied specifically to improve the quality of malaria surveillance data in Kayunga, Uganda. The results of the quantitative evaluation, which will be reported elsewhere, documented an improvement in data completeness following the introduction of the study intervention . The quaPer diem is commonly paid for attendance at meetings and conferences and is embedded in Ugandan practice, with many health workers relying on per diem to top-up their existing salaries. It was not possible to determine whether the CI intervention would have been successful without the extra financial benefits to health workers, and the question of whether any level of compensation can be provided at scale, sustainably, remains.In this context, it appears that much of the CI activity in these health centres was facilitated by the relationships formed by the CI mentor with the health workers, and the supportive ‘supervision’ provided by the mentor. These social relations and practices were also underpinned by the exchange of resources that was associated with the additional work carried out to collect the data. Financial compensation and its potential impact on the intervention’s success and sustainability is an important but sensitive topic. The difficulties of exchanging resources in global health programming has been described by others . If healThis study had several limitations. As a pilot study, it only included public health centres, with a specific focus on the impact of CI on the quality of malaria surveillance data. While three levels of health centres were included, these results may not be representative of the reporting practices and the effect of the CI approach of the entire healthcare system in Uganda. That said, these health centres are typical for Uganda in terms of their recording and reporting practices. The aim of the qualitative evaluation was an in-depth exploration of the inner workings of the CI method for improvement of the surveillance data quality; this intent is best realized through a small study, due to the large efforts required to conduct the qualitative work. Additionally, the recall and reporting bias may be present in situations when health care workers are uncomfortable disclosing their truthful opinions about their health centres, their role in the intervention and the intervention itself. The study attempted to minimize this bias by triangulating data from ethnographic observations, FGDs and in-depth interviews. In addition, during the in-depth interviews researchers assured health workers of the confidentiality of their responses and commitment to reporting the results in a manner that would limit the possibility of identification of specific responders.CI is a promising approach to quality improvement, and could be applied to strengthen the quality of malaria surveillance data. However, successful scale-up of CI in similar low-resource settings may require deployment of highly skilled mentors and raises questions of how feasible it would be without financial incentives. Overall, the analysis presented here poses questions about the feasibility and sustainability of scaling up CI effectively with intensive mentoring, and the cost-effectiveness of such programmes. This pilot project suggests that supportive supervision, like that provided by the CI mentor in this project, was otherwise lacking in these health centres, but is highly valued and desired by health workers. Further research with robust study designs that includes an in-depth qualitative component and ethnographic observation will be required to determine whether CI is likely to be an effective, sustainable or appropriate intervention to improve the quality of HMIS data collection in low-income settings. These could explore whether investing in non-financial incentives that were of concern to health workers  could replace financial incentives that were in evidence in this pilot study. Recognizing that the problems of poor salary and widespread use of per diems goes beyond this pilot intervention, future studies could focus, in part, on the effectiveness of CI at scale, when ‘real-world’ mentors are used and could analyse whether if CI projects could respond to the concerns of staff members then they would be taken up without the need for substantial per diem payments.Additional file 1. Study components.


Farms need to invest in order to earn incomes and maintain their competitive edge. However, the scale and extent of investments must be aligned with resources of other productive inputs, primarily including land, because otherwise there is risk of overinvestment. Since 2004, Central and Eastern European countries have been provided with access to investment support programs; these are non-repayable aid funds which can potentially lead to overinvestment issues. Therefore, this paper attempts to answer the question on the scale of overinvestment in the countries covered. This is all the more important since that problem has rarely been addressed in economic and agricultural research. The study presented in this paper is unique in that the research tasks are based on unpublished Farm Accountancy Data Network (FADN) microdata for 5839 selected Central and Eastern European farms provided by the European Commission’s Directorate-General for Agriculture and Rural Development (DG AGRI). Based on variables relating to the amount of productive inputs and production volumes, the authors developed their own typology of farms which includes the following categories: optimum investment levels (the growth rate of labor productivity is greater than growth in the assets-to-land ratio); relative overinvestment ; absolute overinvestment (labor productivity declines while the assets-to-land ratio grows); underinvestment (decline in both labor productivity and the assets-to-land ratio). The authors demonstrated that members of the ‘absolute overinvestment’ group made flagrant mistakes in investment planning and implementation, whereas members of the ‘relative overinvestment’ group did record an improvement in labor productivity which ultimately can be considered a positive outcome. Underinvested farms were a very small minority in each country. In addition to filling a gap in the methodology for determining agricultural overinvestment, this paper also indicates the scale of that issue in Central and Eastern European countries. This study may be of importance both to farms (as guidelines for investment planning) and to agricultural policymakers who develop investment support programs. Due to its specific production characteristics related to macro- and microeconomic conditions , agriculNumerous studies point to need for agricultural investments because an improvement in agricultural performance is, for obvious reasons, the basis for an increase in food production volumes . The extNevertheless, one should be aware of the threats involved in the investment process which takes on a particular dimension in the agriculture. A frequent problem is that the importance of investments is underestimated. This is due to the particularities of agriculture which requires an intense, though relatively short, use of fixed assets because of production seasonality. Investments can be economically unviable which means the economic operator suffers a loss in the long term. When attempting to estimate investment viability, it can be noted that excessive investments  ultimately result in operational dysfunctions, including overinvestment. That process is manifested by a “higher capital-to-land ratio” , eventuaIn order to identify the extent of agricultural overinvestment, focus must be placed on inefficiencies which occur when the assets-to-labor ratio grows while labor productivity declines . TherefoCentral and Eastern European countries share a common economic history spanning over the last several decades. From the end of World War 2 until late 1980s, they lived under real socialism, a system which can be briefly characterized as the nationalization of a large part of productive inputs and a centrally planned economy. The fall of that system was accompanied by a crisis which ultimately confirmed its economic inefficiency. However, the economic history of agriculture slightly differs between Central and Eastern European countries . In PolaThe purpose of the work is to determine the scale of the overinvestment in agriculture in the countries of Central and Eastern Europe, which since 2004 have been competing on the single European market and may benefit from pro-investment programs supporting the European Union. Based on the assumption of the subordinate role of investment activity in relation to the operational one, it attempted to answer the questions about how the size of the investment affects the relations between production factors and economic results of farms.The paper is organized as follows: Section 2 presents pertinence of the topic. Section 3 describes the unique FADN source data and the research methods employed. Section 4 presents and discusses the key findings. Finally, Section 5 presents the summary, conclusions, relevant political implications and guidelines for further research.Unpublished FADN (Farm Accountancy Data Network) microdata provided by the European Commission’s DG AGRI was used as the source material. The European Farm Accountancy Data Network was established in European Economic Community countries upon initiating the implementation of CAP mechanisms. Note that only commercial farms are monitored by the system. The study presented in this paper is unique in that the research tasks are based on unpublished microdata of selected Central and Eastern European farms. The microeconomic nature of this data makes it also possible to carry out dynamic analyses . Formal This paper relies on the authors’ own classification method which assumes that increasing the value of farm assets through investments is a reasonable thing to do if it results in a proportional growth in labor productivity. Therefore, overinvestment is defined as a situation where:The increase in the value of assets results in a decline in labor productivity, which may be due to high maintenance costs of particular assets (e.g. depreciation). The above is defined as absolute overinvestment.Labor productivity grows at a lower rate than the value of assets. This is referred to as relative overinvestment.Changes in labor productivity were calculated for each farm. Labor productivity was defined as net value added  less operating and investment subsidies per FTE. Net value added was used (rather than family farm income) because of the need to eliminate the costs of external inputs  from the calculation in order to unify the economic performance figures of farms which rely on both their own and external productive inputs. The subsidies were removed from the calculation because public aid cannot be regarded as a metric of labor productivity in the economic sense. This can be assumed even if access to certain subsidies involves  the need to perform specific actions, such as meeting the cross compliance or greening requirements in the case of payments. However, these actions refer to the production of public goods, and therefore do not have a direct impact on economic performance recorded in the market. Average values were calculated for the first and last three years of the study period in order to determine the changes. This was used as a basis for calculating the index for changes as per the formula below:LP: labor productivitySE410: gross farm incomeSE360: depreciationSE406: subsidies on investmentsSE605: total subsidies (excluding on investments)SE010: total labor input (AWU)Changes in the assets-to-labor ratio were calculated as the next step. The value of fixed assets less the value of land per FTE was used as a metric of the increase in the assets-to-labor ratio. The value of land includes agricultural land, land improvement machinery, permanent crops, quotas and other rights attached (including purchasing costs) and forest land. Production quotas (and other rights attached) received free of charge are not appraised in the balance sheet . The rationale behind the above approach is that overinvestment is a problem which ultimately leads to a mismatch between the farm area and the extent of investments in machinery and buildings. Average values were calculated for the first and last three years of the study period, just like in the case of labor productivity. The index for changes was determined next:ALR: assets-to-labor ratioSE441: total fixed assetsSE446: land, permanent crops and quotasSE010: total labor inputAs a next step, each farm was attributed to a group based on the overinvestment criterion:Absolute overinvestment; this is the case for farms where labor productivity drops while the assets-to-labor ratio grows:Relative overinvestment; this is the case for farms where both labor productivity and the assets-to-labor ratio are on an increase but the increase in the assets-to-labor ratio is smaller than the increase in labor productivity:Underinvestment; this is the case for farms where both labor productivity and the assets-to-labor ratio are on a decline.Optimum investments; this is the case for farms where both labor productivity and the assets-to-labor ratio are on an increase, and labor productivity grows faster than the assets-to-labor ratio:Eight indicators were calculated for each group and for each country separately to identify the reasons for overinvestment. Just like in the case of classification ratios, average values were calculated for the first and last three years of the study period for each indicator.Changes in land resources (ha per farm)SE025: total utilized agricultural arean: number of farms covered by this study (by country)Changes in labor resources (AWU per farm)SE010: total labor inputn: number of farms covered by this study (by country)Changes in capital resources (EUR per farm)SE441: total fixed assetsSE446: land, permanent crops and quotasn: number of farms covered by this study (by country)Changes in fixed asset resources in relation to land resources (EUR/ha)SE441: total fixed assetsSE446: land, permanent crops and quotasSE025: total utilized agricultural arean: number of farms covered by this study (by country)Changes in fixed asset resources in relation to labor resources (EUR/AWU)SE441: total fixed assetsSE446: land, permanent crops and quotasSE010: total labor inputn: number of farms covered by this study (by country)Changes in farm productivity (EUR per farm)SE131: total outputn: number of farms covered by this study (by country)Changes in cost intensity at farm level (EUR per farm)SE270: total inputsn: number of farms covered by this study (by country)Changes in Net Value Added (without taking account of operating and investment subsidies (EUR per farm)SE410: gross farm incomeSE360: depreciationSE406: subsidies on investmentsSE605: total subsidies (excluding on investments)n: number of farms covered by this study (by country)The index for changes was defined as follows for each of the indicators listed above:The extent of overinvestment and underinvestment differs across Central and Eastern European countries . The relLand resources owned by a farm are largely decisive for its competitive position and capacity to generate incomes. Both absolute and relative values are important, especially including how they compare to other farms in the country or region concerned. For reasons referred to above , the majority of farms covered by the FADN (i.e. farms which jointly contribute 90% to standard output) are large farms with an average area above 100 ha  in most In each country, farm labor resources  depend bThe differences in capital resources between countries are similar to what was found with respect to land. In this context, note that Polish and Slovenian farms generally have a lower value of fixed assets. The attribution of farms to corresponding groups largely depended on changes in capital resources, and therefore it is obvious that the greatest increments in that productive input are recorded either in the ‘relative overinvestment’ or in the ‘absolute overinvestment’ group . In thesProduction efficiency is conditioned by factors which include appropriate relationships between productive inputs, such as the assets-to-land and assets-to-labor ratios. In this context, note that both the excessively low and excessively high levels reduce the farm’s ability to maximize economic performance. In the former case, this is because capital deficiencies reduce the use intensity of other productive inputs and restrict the production capacity defined as both the quantity and quality of final output. In the latter case, an excessive amount of capital in relation to other productive inputs  adds to costs while not increasing the production scale.In most countries covered by this study, the assets-to-land ratio  reached The potential of today’s agriculture largely depends on the use of capital and of state-of-the-art technologies. Therefore, the higher the assets-to-labor ratio, the greater the competitiveness of a farm. In reality, the inhibiting factor are land resources which either do or do not enable an efficient use of capital owned. This is why in most countries surveyed , the higIt is difficult to estimate the optimum relationships between productive inputs as they depend on a number of aspects, e.g. activity type , cyclical conditions (price relationships) and natural factors (climate and soil conditions). Furthermore, a major role is played by non-measurable factors specific to each farm, such as skills, knowledge and experience of the manager; risk management; production integration, diversification or specialization; particularities of the local market; and the social and economic environment. Nevertheless, the status of and changes in the relationships between productive inputs can be primarily assessed in the context of production and economic performance of a farm or a group of farms.Production and economic performance figures are the ultimate validation of investment decisions. Indeed, it has to be assumed that investment activities are an auxiliary function to operations because the objective of each enterprise (including farms) is to maximize economic value. In turn, from the social point of view of today’s expectations, agriculture requires more and more capital resources and innovative solutions in order to meet the challenge of feeding a growing population, especially as only a small proportion of workforce are employed in agriculture in highly developed countries. However, this general conclusion is not always reflected in farm-level realities. As mentioned earlier, at a micro level, the basic barrier to a reasonable use of capital is the area of utilized land. This is why excessive (unfounded) investments can often lead to stagnation in production and to a deterioration in economic performance. Obviously, the consequences of a lack of investments can be similar or even worse. In the countries covered by this study , productOnce completed, investments can contribute to either a reduction or an increase in costs. The use of more advanced and more efficient machinery and equipment can help making production less energy-intensive, e.g. by reducing the number of runs or by using more fuel-efficient engines. However, the fact alone of having additional fixed assets generates costs such as depreciation, insurance or repair. Moreover, the changes in cost levels should go hand in hand with changes in production levels, ultimately leading to improvements in economic performance. In most cases covered by this study, the ‘relative overinvestment’ and ‘absolute overinvestment’ groups  reportedThey key metrics of viability of investment decisions are the level of and, first of all, the changes in economic performance figures. The performance figures for the base year reflect the resources of productive inputs  owned by farms, the skills in managing the production process and finance, and the general condition of the economy. Conversely, the extent of changes indicates the reasonability of the farms’ strategic measures. The differences between farm groups in each country are an aspect of particular importance in this context because they indicate the effect of various (mainly endogenous) factors. Moreover, as the farms covered by this study operate in the EU single market and in the geographic vicinity of Europe, it can also be assumed that—irrespective of their home country—all of them were faced with the same general economic conditions (mainly including price conditions).nd pillar of the CAP other than investment support; and national support, if any). NVA itself is the difference between production value and production costs less costs of external inputs , adjusted by the balance of taxes and operating payments. Hence, it measures the payment for the use of all productive inputs irrespective of who owns them. As a consequence, it can be used in comparing farms irrespective of whether they operate based on their own or external productive inputs. The amount of subsidies was deducted from NVA because these analyses refer to economic outcomes attained by farms as part of their market activities, and are supposed to indicate the actual efficiency of production processes. The objective of external support is to mitigate the agricultural effects of market failures. However, when taken into account in an analysis, subsidies could distort the true picture of actual outcomes.Economic performance was measured as Net Value Added (NVA) less operating subsidies  . The basFor these reasons, the need to make agricultural investments in the context of a major systemic shift (including the emergence of a number of technologies designed to improve labor productivity) should not give rise to controversy. Particular focus should be placed on investments in precision farming or, very soon, in the Internet of Things or the blockchain technology which are consistent with Agriculture 4.0, a concept that may affect the way food is produced, processed, traded and, last but not least, consumed –49. GeneOverinvestment is a condition where long-term investments are excessively high compared to the production potential  and ultimately become economically unviable because the costs incurred to buy and maintain assets were higher than production outcomes. The term “overinvestment” itself is more often used in an industrial or corporate context, and the way it affects agriculture is described rarely (despite being a common occurrence). According to some studies, public funds used in addition to conventional inputs also greatly contributed to an increase in agricultural production , 52. ThiVarious types of  enterprises get over-invested through an irrational use of assets which is intended to increase company value or have a positive effect on financial performance, but is based on an excessively optimistic evaluation of market conditions –58. As and pillar of the CAP, is one of the important instruments in this respect. Its objective is to support farm investments and improve the structure of farming land [European agriculture is based on plant production, primarily including the cultivation of cereals and industrial crops . Moreoveing land . Major ping land . The groing land , 78. Othing land . Producting land . Anyway,One of the reason to overinvestment in agriculture is also a lack of trust among farmers. Trust is very important in human relations and cooperation in business relationship, especially in agriculture , 81. TheFor Central and Eastern European countries, joining the EU was a great leap forward, including in the agricultural sector. Aid funds allocated to farm investments played an important role in that respect, allowing many operators to catch up with progress . The investments implemented by some farms were excessive in relation to their production potential. Conversely, other ones gradually discontinued their farming operations as they saw no opportunity for gaining a competitive edge.This study confirmed that investments have a complementary nature vis-à-vis operations. Indeed, production processes require adequate capital resources, whereas economic performance is what ultimately validates investment decisions. This paper used two essential criteria in assessing these aspects: the absolute increase in economic outcomes, and how it relates to the increase in capital resources. This allowed to identify two types of farms, namely the ‘absolute overinvestment’ and ‘relative overinvestment’ groups. The first case is a symptom of manifest errors in investing , since large amounts of investment expenditure were accompanied by a decline in economic performance. In this context, note that it was not the consequence of unfavorable price relationships because other operators recorded improvements despite dealing with the same market conditions. Things look slightly different in the ‘relative overinvestment’ group. They saw an improvement in economic performance, which is the goal sought by every economic operator. However, the growth was slower than the increase in capital resources. On the one hand, this could suggest excessive investment took place; but on the other hand, these measures could have been required because of the particularities of production. The second interpretation seems more justified as that group exhibited the highest net value added in all countries surveyed .When assessing the Union program for investment support on an overall basis, it is necessary to exercise extreme caution in the interpretation because some of the relevant decisions were made otherwise than in the context of availability of aid funds. Nevertheless, support from the EU was significant and must be evaluated. Undoubtedly, farms at optimum investment levels should be viewed as being in a positive situation; in their case, economic performance grew faster than capital. In the context of this discussion , the activity of the ‘relative overinvestment’ group should also be considered a positive development. Despite a decline in most ratios, there was a specific rationale behind the measures taken by small and underinvested farms. Dealing in a specific national context and not having a competitive edge, they gradually discontinued their farming activities. Hence, actual and manifest errors were made in the ‘absolute overinvestment’ group. When assessing the rationality and efficiency of the Union support program, note that the share of this group in the total number of farms ranged from a few to more than ten percent, depending on the country (it went beyond 20% only in Poland). This means that—despite being tempted to abuse the non-repayable aid scheme—most farmers did the right thing and acted responsibly, in accordance with their market position. It could be explained by the fact the farmers contributed their own funds and realized that assets generate costs. The formal barriers to access aid programs and the verification of project plans by the granting institutions could have played a certain role, too.


N = 1039). The second measurement (N = 400) was carried out in December 2020 to test if the pandemic influenced the trust in different sources of information. Results: The final analyses carried out on final sample of 400 participants showed that there has been no change in trust in the Internet as a source of knowledge about health during the pandemic. However, the trust in science, physicians, subjective health knowledge, as well as the attitude towards the vaccination has declined. Regression analysis also showed that changes in the level of trust in physicians and science were associated with analogous (in the same direction) changes in attitudes toward vaccination. The study was also focused on the trust in different sources of health knowledge as possible predictors of willingness to be vaccinated against SARS-nCoV-2. However, it appeared that the selected predictors explained a small part of the variance. This suggests that attitudes toward the new COVID vaccines may have different sources than attitudes toward vaccines that have been known to the public for a long time.Background: The research focused on the relationships between attitudes towards vaccination and the trust placed in different sources of information  before and during COVID-19. Method: A longitudinal design was applied with the first measurement in February 2018 ( Despite overwhelming medical evidence and the unanimous position of medical professionals in favor of vaccination, the number of people skeptical about vaccination has grown in many countries in recent years. The consequence of this alarming trend is a decline in immunization coverage . The proIn our study, we approached the problem of attitudes toward vaccination not from the perspective of personality traits, but by treating it as a manifestation of the broader problem of trust in science and experts’ opinions ,5,6. ThiA lot of data show that advice from healthcare experts is the most influential source of information about vaccination for most people . HoweverThe downturn in trust in vaccines may be a manifestation not only of declining trust in physicians, but also of a broader social trend of diminishing trust in science . While sConsidering the above, our goal was to investigate whether the attitudes toward vaccination  may stem from the trust in physicians and/or anti-scientific attitudes. Moreover, we wanted to investigate how the COVID-19 pandemic has influenced these attitudes.Over the past few decades, the Internet has become an important source of medical information for patients. People often visit websites to explain or diagnose their physical ailments; they also consider the Internet an easily accessible source of information about vaccinations ,21. HoweTaking the above considerations into account, we included trust in health-related information presented on the Internet as a possible predictor of attitudes toward vaccination (including vaccination against COVID-19). We also wanted to investigate whether the pandemic would change this level of trust and its impact on the attitudes toward vaccination (compared to in 2018).In our study, we also hypothesized that attitudes toward vaccination may be related to beliefs about one’s own health-related knowledge. We based these assumptions on previous research into subjective knowledge. Research on judgments and decision making has a long tradition of distinguishing between objective knowledge and subjective knowledge ,26. ObjeAlthough many studies show that people tend to positively evaluate their own knowledge in various areas, the doubts and uncertainty associated with a pandemic may have changed these optimistic beliefs. Therefore, in the second measurement we decided to repeat the questions about the assessment of the participants’ own knowledge in the area of health. We also wanted to determine whether assessing one’s own knowledge would prove to be a significant predictor of attitudes toward vaccination.To sum up all the above considerations, our research goal was to test the trust in physicians, science, the Internet and one’s own knowledge as predictors of attitudes toward vaccination, before and during the COVID-19 pandemic. We also applied a longitudinal design to investigate whether the attitudes toward the sources of health information and toward vaccines changed after the breakout of the pandemic or remained relatively stable.N = 1039) took part in the first measurement (February 2018). The study was run online by the Ariadna Nationwide Research Panel, a Polish counterpart of mTurk—a company specialized in the polling of large samples for the purpose of research. The panel enables random selection of a sample from among 300,000 registered and verified persons. The socio-demographic profile of the persons registered on the panel corresponds with the profile of Polish internet users. Additionally, Ariadna has been awarded certificates issued by recognized organizations associated with social research companies (including ESOMAR). For participation in the survey, respondents received credit points that they could exchange for gifts.A representative sample of the Polish general population , age (5 subgroups and place of residence (5 subgroups), each demographic criterion controlled to be representative of the Polish general population, giving a total of 50 weighted cells. Weights were calculated based on these three demographic criteria, and participants were drawn randomly from cells to fit demographic quotas. Because we decided to apply a longitudinal design, we tried to reach the same group of respondents in December 2020. Reaching the same sample for a second time was possible as Ariadna uses unique identifiers for their respondents and there is a possibility to reach out to particular respondents inviting them for a given survey.N = 400, 175 women and 225 men. A total of 24% were aged 18–34, 31% were aged between 35–54 and 45% were aged 55 or older. Moreover, 12% had primary or vocational education, 45% had secondary or postsecondary education and 43% had a bachelor’s degree. The proportion of men to women was significantly higher in this final sample than in the original one, and there was an age difference signifying a systematic dropout of the younger population. The sample retained its structure regarding residence and education.However, in the second measurement we were able to reach only some of the participants from this group, and we finally conducted analyses on the individuals who participated in both the first and second measurements. Therefore, the final sample was Questionnaires were presented online on the same survey platform in 2018 and 2020. The questionnaire consisted of 21 single-choice items which required on average 10 min. to be completed, and it was divided into six main categories: (a) demographic data, including age, gender, education, place of residence; (b) trust in physicians was measured with three statements . The responses to statements were measured on an 11-point Likert scale from 0 (strongly disagree) to 10 (strongly agree); (c) subjective health knowledge was measured with four questions . The responses to the statements were measured on an 11-point Likert scale; (d) trust in science was measured with four statements . These statements were based on Farias and Reiman’s  Belief iThe study protocol was reviewed and approved by the Ethics Committee of the Institute of Applied Psychology, Jagiellonian University in Krakow (Poland). The questionnaire collected no identifying personal data from the participants.The IBM SPSS Statistics (SPSS) software version 26 was used to perform the statistical tests—repeated measures ANOVA and multiple linear regression.In the first step of the analyses, we applied a Repeated-Measures ANOVA to assess the possible difference in trust toward different sources of health information and in attitudes toward vaccination between February 2018 and December 2020. The results revealed that mean scores for trust in physicians, trust in science, subjective knowledge and attitudes toward vaccination significantly decreased across the two time points, showing a significant time effect for these factors . Trust iIn the next step of the analyses, we conducted a separate multiple linear regression analysis for two measurements (in February 2018 and in December 2020), with attitudes towards vaccination as the dependent variable, and four independent variables: trust in physicians, trust in science, trust in the Internet as source of health information and subjective health knowledge .For the first measurement (February 2018), the regression model for attitudes towards vaccination explained about 34% of the variance. The trust in physicians, trust in science and trust in the Internet were the significant predictors of attitudes towards vaccination. The trust in physicians and trust in science had positive regression weights, showing that the higher the trust towards both these sources, the more positive is the attitude towards vaccination. The trust in the Internet had negative weights, which demonstrates that the more people that believe in the Internet as a reliable source of information about health, the less positive is their attitude towards vaccination. In the first measurement subjective knowledge did not contribute significantly to attitudes towards vaccination.For the second measurement (December 2020), the regression model for attitudes towards vaccination explained about 49% of the variance. In this measurement, the four factors (including subjective knowledge) significantly predicted the attitudes towards vaccination. The trust in physicians and trust in science again had positive regression weights showing that the higher the trust towards both these sources, the more positive is the attitude towards vaccination. Trust in the Internet and subjective knowledge had negative weights. It demonstrates that the more people believe in the Internet as a reliable source of information about health and the higher they evaluated their health knowledge, the less positive is their attitude towards vaccination.In this research, we also wanted to investigate if the changes in trust towards different sources of health information across two time points (February 2018 and December 2020) influenced the changes in attitudes towards vaccination across these two time points. In this purpose, we created rates of change for the dependent variable and for the three predictors by subtracting the result of measurement one from the result of measurement two. We did not create an indicator of change for trust in the Internet because the Repeated-Measures ANOVA showed that it did not change significantly over the two measurements. We then conducted a regression analysis, with changes in attitudes towards vaccination as the dependent variables, and three independent variables: changes in trust in physicians and in science, as well as changes in subjective health knowledge .The regression model for changes in attitudes towards vaccination explained about 17% of the variance. The changes in trust in physicians and trust in science, as well as the changes in subjective knowledge were the significant predictors of changes in attitudes towards vaccination. The changes in trust in physicians and trust in science had positive regression weights. That is, changes in trust toward these sources in a particular direction were associated with changes in attitudes toward vaccination in the same direction . On the contrary, the changes in subjective knowledge had negative weights. It demonstrates that changes in these factors in a particular direction were associated with changes in attitudes toward vaccination in the opposite direction In the third step of our analyses, we conducted a separate multiple linear regression analysis for the second measurement (in December 2020), with attitudes towards vaccination against SARS-nCoV-2 as the dependent variable, and four independent variables: trust in physicians, trust in science, trust in the Internet as source of health information and subjective health knowledge .The regression model for attitudes towards vaccination against SARS-nCoV-2 explained about 12% of the variance. The trust in physicians and trust in the Internet were the significant predictors of attitudes towards vaccination against SARS-nCoV-2. The factors had positive regression weights showing that the higher the trust towards both these sources, the more positive is the attitude towards vaccination. The trust in science and subjective knowledge did not contribute significantly to attitudes towards vaccination against SARS-nCoV-2.In the last step of the analysis, we also wanted to investigate if the changes in trust towards different sources of health information across two time points (February 2018 and December 2020) influenced the attitude towards vaccination against SARS-nCoV-2. We then conducted a regression analysis, with attitude towards vaccination against SARS-nCoV-2 as the dependent variable, and four independent variables: changes in trust in physicians, in science and in the Internet, as well as changes in subjective health knowledge. However, the percentage of explained variance appeared to be very low (0.2%); therefore, we did not present specific results.In this research, we focused on the influence of trust in physicians, science and the Internet as well as subjective knowledge on attitudes toward vaccination. Our second aim was to investigate the possible changes in the aforementioned factors across two points in time—February 2018 and December 2020, during the second wave of the pandemic. In addition, we wanted to test whether trust in various possible sources of information about health and its changes over time was related to willingness to be vaccinated against SARS-nCoV-2.The results of the study showed that trust in physicians, science and the Internet were strong predictors of the attitudes toward vaccination at two points in time. The higher the trust in doctors, the more positive the attitudes toward vaccination, and conversely, lower trust is associated with higher skepticism toward vaccination. These results confirm the evidence obtained in many previous studies, showing that trust in physicians has a positive effect on vaccination intention and the provision of information by health professionals and the quality of their information are essential for the decision of whether to be vaccinated ,33. HowePerhaps the decrease in trust in physicians is a result of healthcare problems faced by many countries (including Poland) during the pandemic. The results of public opinion polls show that many people are not satisfied with healthcare during the pandemic. It is difficult to arrange a traditional surgery visit, regardless of the specialization of the physician, and many patients do not trust e-visits or telehealth consultations, which cannot replace direct contact with a healthcare provider. Appointments with specialists are often subject to long waiting times and access to tests, even basic ones, is difficult .Our results showed that between the years in which we conducted the studies, trust in science also declined, which was again associated with a decline in positive attitudes toward vaccination. In our view, this result can be explained in several non-exclusive ways. Perhaps this is due to an observation that scientists appeared for a long time to be losing the battle against the pandemic due to insufficient knowledge, and the belief that they failed to quickly identify and control the spread of the coronavirus. Perhaps the sense of one’s own helplessness, ignorance and uncertainty in the face of the pandemic also caused a decline in subjective health knowledge (which appeared to be the weakest predictor of attitudes toward vaccination).experts-should-converge effect [At the time of the pandemic, another element is apparent that may play a significant role in reducing trust in science and its representatives—inconsistencies in the opinions they present. Since the emergence of COVID-19, discussion of the virus has been characterized by considerable disagreement among scientists and health experts observed on a number of issues, including what the origin of the coronavirus was, who is most vulnerable to infection and how effective certain treatments are ,36. Howee effect , people e effect  explainse effect ,39.Trust in the Internet also appeared to be a strong predictor of the attitude toward vaccination in both measurements. However, in this case, the relationship was reversed. The more people trust the Internet as a source of health knowledge, the less positive their attitudes toward vaccination. There are two possible reasons for this. First, people who trust the credibility of information found on the Internet and search it for information about vaccinations may often end up with arguments spread by antivaccine activists which negatively influence their attitudes toward vaccination. It must be remembered that the Internet is blamed for the rise in vaccine skepticism. Due to widespread access to this powerful source of information, the arguments of anti-vaccine activists can be easily published and distributed, reaching many people and raising concerns regarding vaccination among some of them ,40. MoreIn our study, we investigated not only attitudes toward vaccination in general, but we also focused on the trust in different sources of health knowledge as possible predictors of willingness to be vaccinated against SARS-nCoV-2. However, in this case we found that the predictors we selected explained very little of the variation of the outcome variable. This result is very interesting because it shows that attitudes toward the new COVID vaccines may have different sources than attitudes toward vaccines that have long been known to the public. Our previous research (in preparation) shows that they are strongly associated with, among other things, the opinions people have about the pandemic , the fear of being infected or the perceived likelihood of being infected.A limitation of our study may be the final number of subjects whose responses were analyzed. However, it is important to note that we used a longitudinal design and attempted to reach the same individuals almost three years later, which caused us to lose some respondents from the original sample. Additionally, with this design, we were able to see how attitudes had changed over such a long period of time (within subjects). Moreover, we were interested not so much in describing current attitudes toward vaccination in society (as there are many studies on this topic), but in examining how they are related to our predictors and how this relationship has changed over such a long period of time.Another limitation of our research stems from the fact that when analyzing the predictors of people’s attitudes to vaccination (and changes in their opinion), we only took into account a few factors—belief in science and its achievements, belief in the correctness of experts’ opinions, and belief in the truthfulness of information that can be obtained from the Internet. While these variables were directly associated with the aims of our original 2018 study, there is no doubt that the list of factors which may serve as predictors of dynamics of human vaccination attitudes is much longer. First of all, in future research it is worth looking closely at the role of risk perception. While the research to date has considered the role of perceived risk in vaccination decision-making and vaccination attitudes ,43, as f


Microbots have been considered powerful tools in minimally invasive medicine. In the last few years, the topic has been highly studied by researchers across the globe to further develop the capabilities of microbots in medicine. One of many applications of these devices is performing surgical procedures inside the human circulatory system. It is expected that these microdevices traveling along the microvascular system can remove clots, deliver drugs, or even look for specific cells or regions to diagnose and treat. Although many studies have been published about this subject, the experimental influence of microbot morphology in hemodynamics of specific sites of the human circulatory system is yet to be explored. There are numerical studies already considering some of human physiological conditions, however, experimental validation is vital and demands further investigations. The roles of specific hemodynamic variables, the non-Newtonian behavior of blood and its particulate nature at small scales, the flow disturbances caused by the heart cycle, and the anatomy of certain arteries  in the determination of the dynamic performance of microbots are of paramount importance. This paper presents a critical analysis of the state-of-the-art literature related to pulsatile blood flow around microbots. Cardiovascular diseases (CVDs) are the leading cause of death worldwide (17.9 million) . The numOther methodologies concerning numerical methods such as computational fluid dynamics (CFD) have been used to analyze flow behavior regarding hemodynamic analysis in blood vessels to better understand the development of CVDs ,9,10. ThDespite the recent advances in implementing experimental and numerical studies related to the hemodynamics around microbots, these investigations are still scarce. Understanding the influence of the microbots’ morphology on the flow dynamics to have an efficient device capable of moving through different blood vessels, especially to minimize CVDs, considering the vessels’ morphology, non-Newtonian properties of blood, and pulsatile flow, is of paramount importance and needs more attention.In this review, the most important potential applications of the use of microbots in the human circulatory system are summarized in CVDs are the leading cause of death worldwide; more people die annually from CVDs than from any other cause. Among cardiovascular disorders, the major causes of death are due to vascular obstructions, caused mainly by thrombus formation or atherosclerotic plaques ,18. The Alternative procedures are preferred whenever possible, such as percutaneous coronary intervention (PCI). It is a reliable procedure that is much less invasive and expensive than CABG, and it combines a coronary angioplasty with stenting ,23. PCI Minimally invasive procedures underwent significant advances in the last decade. A good example of this is the use of tiny robots for operations in the vascular network. Microbots offer significant opportunities in future targeted medical interventions . They haAccording to Miloro’s classification , one theAnother interesting strategy proposed in Miloro’s classification  would beIt is important to note that microbots could be well suited to perform tasks by means of mechanical, laser, and hybrid removal actions. They could be adapted with specialized design tools to accomplish those tasks, or they can act as simple static structures whose positions are handy or even self-oriented. They could be easily used in a rotary motion for scraping a fatty material from the internal wall of blood vessels or use a resonating mechanical structure to emit ultrasonic pressure waves to destroy a calcified material which could be obstructing a vessel ,27,28. AAnother approach would include chemical removal strategies involving chemical reactions such as chemical dissolution or disruption of a lytic agent to target and destroy the biological structure of obstructions. These types of clinical therapies , besides easy administration, widespread availability, and proven efficacy, only attack thrombi in arteries and veins and could lead to some clinical risks such as intracranial hemorrhage, systemic hemorrhage, immunologic complications, hypotension, and myocardial rupture . SeveralDogangil et al.  concludeFinally, another potential strategy suggested by Miloro et al.  focuses microswimmers with characteristic dimensions less than 1 mm. Recently, there have been many applications and several novel designs of microbots that have emerged; nevertheless, before introducing them, it is necessary to give a simple overview in order to specify the type of microbot that we are describing in this review. Most of the promising microswimmers are designed to make delicate micromanipulations in unreachable environments for medical purposes. Those environments inside the human body are conditioned by all the body fluids, and it is expected that these tiny robots will swim in these fluid environments, traveling and applying their functionality in different parts of the human body. The main environment that we are focused on in this review is the circulatory system, but there are other locations in the human body where microbotics research has been successfully applied, such as the gastrointestinal system [Microbotics research has recently become an important topic regarding the design, study, and application of miniature robots for medical and biological purposes. These robots are generally mobile robots or l system , urinaryl system , centrall system , eye [29l system ,34. Therl system  systemat(a)Ciliary microbots. Kim et al. [m et al.  develope(b)Soft attractor wall microbot. Aghakhani et al. [i et al. ,37 devel(c)Self-folding microbot. Breger et al. [2O3) nanoparticles in the porous hydrogel layer, allowing the microgrippers to be responsive and remotely guided using magnetic fields. They illustrated the operation and functionality of these polymeric microgrippers for soft robotic and surgical applications, such as capturing and performing an excision of cells, such as fibroblast clumps. They could also be used for drug delivery purposes. Small oscillations in the temperature of blood would modify the shape of the microbot and, therefore, may alter its hemodynamics without control.r et al.  proposed(d)Sperm-shaped microbot. Another microbot inspired by natural structures consists of a head connected to a flexible tail, similar to a sperm cell [erm cell ,40. This(e)Snake-shaped microbot [microbot . Kim et microbot , introdu(f)Scallop-shaped microbot. This design was proposed by Qiu et al. [u et al.  and is a(g)Microrocket robot. This design was recently proposed by Li et al. [i et al.  and solv(h)Surface microrollers. Alapan et al. [n et al.  reported(i)Helical microbots. Helical microbots are another commonly studied design, aiming at targeted drug delivery, cell sorting, and cell characterization. They used helical propulsion to break time-reversal symmetry and provide locomotion at a low Reynolds number in the bloodstream via the action of a uniform or non-uniform rotating magnetic field. Helical microbots could be used for rubbing against blood clots [od clots . Khalil od clots  experimeIn this review, we are focused on the shape of the microbots, as it is responsible for allowing the best hemodynamic performance of a microswimmer inside the circulatory system.To reach the best design for proper locomotion through the vasculature system, several researchers around the globe are developing different shapes for microbots. In this sense, it is worth mentioning the worldwide leading position of Sitti and co-workers of the Physical Intelligence Department at the Max Planck Institute for Intelligent Systems in the development of pioneering designs of miniature medical mobile robots . Figure Of course, all the above-mentioned designs would require further analysis of the biocompatibility and long-term tests to assess the toxicity in in vivo/in vitro environments before application in real cases. Concerning biocompatibility, safety risks could be mitigated by constructing the microbots from materials intrinsically compatible with physiological environments. Ceylan et al.  proposedThus, although in recent years there has been a huge advance in microbot technology, particularly in the design of microbots dedicated to the treatment of cardiovascular diseases and drug delivery purposes through the human circulatory system, there is still much to be done in this multidisciplinary field, particularly in the analysis and study of the hemodynamics of the microbots in the human circulatory system, which would allow understanding and determining which are the physical parameters of the physiology that could offer potential challenges for microbot applicability in the treatment and diagnosis of CVDs.From the engineering point of view, the human circulatory system could be explained as a fully optimized in vivo fluid mechanics lab that works in perfect harmony. This living lab is equipped with a closed circuit composed of several channels with different calibers (blood vessel network), a brilliant and well-designed pump (the heart), and a complex fluid with incomparable properties (blood). When we imagine a micro/nanorobot swimming through this system it is easier to compare this lab to a science fiction movie, as Sitti et al.  once wroThe blood vessels are absolutely essential in this system to ensure the normal distribution of blood containing nutrients, oxygen, water, and hormones to all living tissues and organs as well as to remove the metabolic waste byproducts and carbon dioxide from all the tissues and organs on the way to the lungs. They are essential to blood pressure regulation and to the maintenance of body temperature.The blood vessels can be classified into five types, i.e., arteries, arterioles, capillaries, venules, and veins; however, we could simplify and classify them into three major groups by their function and structure:Group I: Arteries and small branches (arterioles): the main function is to distribute from the heart the oxygen-rich blood with all metabolic byproducts to all regions of the body. These vessels are normally highly pressurized, excluding the pulmonary artery. Their structure is composed of three layers called the tunica intima, media, and adventitia. They can be divided into three types by the structure of their walls and main functions:Elastic arteries , which are characterized by a thin wall and a larger diameter  and this type of artery receives blood directly from the heart, so their walls contain high elastin concentrations, allowing them to stretch and support high blood pressure.Muscular arteries or distributing arteries , as the name indicates, distribute the blood to all the organs and tissues. This type of artery is composed of a high concentration of smooth muscles. The range diameter is 0.1 to 10 mm.Arterioles are the smallest type of artery. They work as resistors causing a drop in blood flow pressure and their average vessel diameter is 30 Group II: Veins and small branches (venules): the main function is taking the oxygen-poor and carbon dioxide-rich blood back to the heart. Typically, these vessels have low pressure and their classification is based on depth, function, and geometry. Similar to arteries, vein walls are constituted of three layers, however, they are much thinner. The diameter of veins is from 20 us valve ,51.Group III: The capillaries: capillaries have an important role in exchanging metabolic substrates and waste byproducts between blood and tissues. The capillaries make the connection between arteries and veins through arterioles and venules. They are narrow and thin-walled, making them the smallest of all the blood vessels  between the blood flow and the wall of the vessels. This topic has been recently reviewed by Campo-Deaño et al.  and it iBlood vessels commonly bifurcate numerous times until they become capillaries. There are some sites where arteries can bifurcate, trifurcate, or even quadrifurcate ,54,55. AThe human heart could be defined as a simple and efficient flow pump whose operation (approximately 72 beats/min) is equivalent to 1.2 Hz. The duration of a beat is approximately 0.830 ms. The heart works as two pumps in series. To ensure this function, the blood travels unidirectionally through valves inside these pumps , preventing the back-flow of blood. At the beginning of a heartbeat, a cardiac event correlates the blood flow and pressure that occurs until the next heartbeat. This event is of paramount importance and it is called the cardiac cycle. William Harvey was the first researcher demonstrating blood circulation under pulsatile flow where the amount of blood is finite . The effUnsteady, pulsatile flow through nearly all of the cardiovascular system dominates many aspects of the system. Pressure gradients regulating blood flow through the heart suffer a great variation as well as the constantly loaded and unloaded stresses applied to the artery wall ,57. XiaoAnother important aspect of the circulatory system is the blood pressure along the full vasculature. Here, it is important to distinguish two types of circulation: macrocirculation and microcirculation. This classification could be carried out considering the network of large arteries and veins up to small arterioles and venules (macrocirculation). Here, the microcirculation starts, corresponding to the entire microvasculature involving the blood flow in arterioles, capillaries, and venules. Therefore, microcirculation is the last station to provide the nutrients for the living tissues of the system. Moreover, macrocirculation has a supporting function that consists of reducing the pressure oscillations resulting from the intermittent ventricular ejection and transforming the pulsatile flow into steady flow required for oxygen supply in the pulmonary microcirculation system . HoweverTaking into account the properties of human blood , the characteristics of the blood flow (velocity and frequency), and the dimensions of the main vessels (diameter), we define the set variables , and V is the fluid velocity (m/s). Normally, the Reynolds number is an asset to evaluate the fluid flow regime.a stroke .The Deborah number .The Weissenberg number (Wi) is a dimensionless group representing the ratio between elastic forces and viscous forces [s forces .(3)Wi=λA wide range of complex fluids are characterized by their relaxation time , which can be seen as the reciprocal of the characteristic time of the deformation process defined above (T). In the circulatory system, the frequency generally is measured by the heartbeat rate. The Womersley number has an influence on the shape of the velocity profile and, typically for high values of The Strouhal number is a dimensionless number typically used in fluid mechanics to describe oscillating flows. The Strouhal number for a channel (or pipe) can be defined as:This parameter is mostly considered in the study of unsteady oscillatory blood flow of arteries with irregular shapes and within aneurysm formation. Stalder et al.  investigtic arch . With thtic arch  in theirThus, for unsteady viscoelastic flows, as is the case of the flow of blood inside the human circulatory system, we can writeIt is important to note that whenever there is more than one dimensionless group, dimensional analysis places no restriction on which groups we derive .From all the information provided in The literature considering the unsteady flow of viscoelastic fluids in a channel is rather scarce, although it has been growing since the 1990s. In pulsating flows of viscoelastic liquids, the relation between dynamic and kinematic characteristics of the flow appears to be more complicated than in a Newtonian fluid, as the stress tensor is not related directly to the deformation rate tensor at any given instant, and the phase shift between the velocity and pressure gradient is not defined by flow inertia alone .Several experimental studies have been developed at the macroscale, where the elastic forces are far less important than the viscous forces. They typically control the time-varying pressure gradient  or flow Numerical studies of viscoelastic fluids in pulsating flows have also increased considerably in recent years, particularly because the instability or convergence issue at a high Weisenberg number (Wi) or Deborah number (De) has been successfully tackled with a variety of approaches that allow for stabilizing the numerical solution such as the log-conformation tensor approach, among others . These tHydrodynamics around macroscopic objects, such as the canonical case of a cylinder in a cross-flow, have been thoroughly studied for Newtonian fluids for more than a century, since Prandtl’s conceptualization of the boundary layer . HoweverCardiovascular diseases, and particularly vascular obstructions due to thrombus formation of atheroma, are responsible for fatal accidents. There are different strategies to solve these health issues in order to prevent severe problems. Biomedical research aims to provide new solutions, which tend to be uninvasive as possible for the patient and this is where microbots may be of paramount importance for future treatments of CVDs. The most likely potential applications of the use of microbots in the human circulatory system have been reviewed, and the most recent and relevant microbot designs have been critically assessed.The human circulatory system is a closed circuit consisting of a viscoelastic liquid, i.e., blood; channels with different dimensions and elasticity, which affect the flow dynamics of the blood, namely velocity and pressure; and a pump, i.e., the heart, which imposes a pulsating nature on the blood flow. This is a very complex environment that represents a true challenge for the navigation of medical microbots, from any perspective, i.e., analytical, numerical, or experimental. In this manuscript, we have also revised the state of the art of blood flow dynamics around medical microbots, highlighting the works that have been developed, their limitations, and the remaining empty gaps to be filled in this field of research. Regarding the design of the microbots, future works should try to reduce the size of the microbots to reach smaller vessels; moreover, studies on biocompatibility analysis of the microbots and long-term toxicity would allow for determining the most suitable materials to be used in the next generation of microbots for CVD treatments. Finally, the major challenge is determining how the pulsatile nature of blood flow may affect the performance of the microbots; the analysis of the blood flow dynamics around the microbots may provide relevant information for the definition of the right morphology of the microbots to obtain optimal performance. We hope this work motivates the community to work on the analysis of blood flow dynamics around microbots so that the generated knowledge may allow better control of microbot dynamics.


Coronary Artery Anomalies: A 2020 Review” in Frontiers in Cardiovascular Medicine aims to address some of the major questions in the setting of CAA. We thank the authors for their eminent contributions and it is with great pleasure that we can present eight interesting articles on this important topic from different internationally recognized research groups in the field of CAA.Coronary artery anomalies (CAA) are one of the remaining mysteries in cardiology. Currently, reports of an anomalous coronary vessel origin/and or course is rare , but witThiene et al. and Rizzo et al., both from the University of Padua, for the two first articles. They nicely summarize the history, the embryology, and anatomical aspects of CAA by illustrating different aspects with historical pictures, excellent drawings, images from postmortem casts, and pathological specimens. The anatomy of subepicardial coronary arteries in normal hearts and its right, left, or co-dominance was first published in a milestone paper in 1903 by Antonio Banchi, an anatomist in Florence, and then confirmed by post-mortem casts in 1963 by Giorgio Baroldi and shortly after in vivo by Sones at the Cleveland clinic. From the embryology point of view, the supepicardial vessels derive from extracardiac epicardial cells, which form a plexus like vasculature secondary invading the myocardium and growing toward the aortic root to the facing aortic sinuses . During this process a misconnection to the wrong sinus of the Valsalva can occur, however, its exact pathological mechanisms seem to be still not well-understood. Four rare anomalies are nicely presented and discussed in different clinical settings in the articles published by Borns et al. and Tang et al.. One case was a 7-year-old girl diagnosed with a single left coronary ostium with a giant coronary trunk, coronary artery to right ventricle fistula, and coronary artery ring. The authors documented the case very well and it is the first described variant of its kind in the literature. The coronary fistula was surgically ligated with an off-pump strategy and the patient was discharged on day five post-operation and free of symptoms during the 3 years of follow-up . The three other cases by Borns et al. were a 14 years old teenager with left ACAOS with acute chest pain and elevated troponin, a 15-year old girl with a right ACAOS with chest pain, and an 11 year- old girl with syncope after swimming and ventricular fibrillation and an anomalous origin of the left coronary artery arising from the non-facing sinus without an interarterial course, but with a short intramural course. Low-dose computed tomography with 0.38 mSv and 60 ml contrast or cardiac magnetic resonance imaging were used in these cases and seem to be the optimal anatomical imaging modality to exactly describe the anatomy. As all these cases presented with acute signs and symptoms of ischemia due to the underlying CAA, timely surgical correction was performed. The three cases showed an intramural course and therefore the surgical approach was unroofing . Interestingly enough, in the case with an anomalous coronary artery originating from the non-facing (non-coronary) sinus without an interarterial course, a long  intramural course was confirmed intraoperatively and therefore it seems that the anatomical high-risk feature of intramural course has to be considered separately from the interarterial course and is not always linked to it. In this regard, Bigler et al. illuminate in a comprehensive and in-depth review the pathophysiology of different anatomical high-risk features of CAA and how hemodynamic relevance should be assessed. The concept of a fixed component, similar to the stenosis known from coronary artery disease  and additional dynamic component  is discussed. It is highlighted that patients with a CAA should not be invariably referred to direct surgery, but rather should undergo a thorough noninvasive and invasive assessment. This includes an anatomic description of the anatomy (best done with computed tomography or cardiac magnetic resonance) and additional functional testing with dobutamine/volume challenge under maximal heart rate  . However, the authors emphasize that besides the assessment of ischemia, one has to be aware of the possible presence of myocardial fibrosis and scarring  which may serve as the substrate for ventricular tachyarrhythmia's, and has to be taken into account for risk stratification of patients with CAA. Regarding the optimal surgical approach, Padalino et al. elaborate a complete review on the various surgical techniques , which are usually devoted to a particular anatomical subtype of CAA. Although ideally, the coronary surgical reconstruction for CAA should normalize the anatomy, relocating the large ostium in the center of the appropriate sinus, reproducing a normal take-off angle, and eliminating any intramural or interarterial course, none of the current surgical techniques can address all of these components, and each is susceptible to individual technical pitfalls . To document and control treatment success, Meijer et al., propose a compelling imaging approach in their original study. In detail, 11 patients were retrospectively identified out of 54 consecutive patients who underwent surgical repair of CAA over a 17 year period at the Leiden University Medical Center, and who had pre- and post-operative computed tomography imaging available. The origin and course of the anomalous coronary artery and the ostial dimensions were evaluated and correlated with restenosis of the operated coronary artery. To allow an accurate evaluation of the effective orifice area at diagnosis and after surgical repair introduced a new parameter—the coronary triangulated orifice area (CTOA). In fact, postoperatively, the median CTOA increased significantly from 1.6 mm2  to 5.5 mm2  (p < 0.005). During follow-up, in three patients restenosis of the operated coronary artery was suspected and in these patients the CTOA showed only a limited postoperative increase of ≤ 1.4 mm2. This study highlights, that patients with CAA undergoing surgery should be closely monitored and possibly benefit from post-operative imaging to derive the new anatomic circumstances. Besides surgery, percutaneous coronary intervention (PCI) might be another alternative approach in selected patients with CAA. In an interesting overview by Aubry et al. the role of PCI in patients with CAA and interarterial course is presented and discussed. There is not much literature published on PCI in CAA so far, and we congratulate the authors for establishing the ANOCOR working group which, since 2014, has started a prospective registry of patients with right coronary artery anomalies and evaluated the outcome of those treated by PCI with stenting. The strengths of PCI are a shorter hospital stay and fewer post-procedural adverse events compared to surgery, however, long-term potency is not well-known and this approach might be rather a possible future strategy for older patients and not for younger adults or children. Furthermore, PCI may be a bail-out strategy to treat some surgery failures, such as acute occlusion or scarring stenosis .We congratulate the authors ClinicalTrials.gov ID: NCT04475289) and MuSCAT trials .The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.