Although the use of biomarkers to assess health outcomes has recently gained momentum, literature is still scarce for low- to middle-income countries. This paper explores the relationship between primary care coverage and individual health in Brazil using a dataset of blood-based biomarkers collected by the Brazilian National Health Survey. Both survey data and laboratory results were crossed with coverage data from the Family Health Strategy (ESF) program, the most important primary care program in Brazil; the coverage measures aim to capture both direct (household) and indirect (spill-over) effects.The empirical strategy used a probit model to estimate the relationship between ESF program coverage and the likelihood of abnormal biomarker levels while controlling for a rich set of individual and household characteristics based on data from the national survey.Household ESF coverage was associated with a lower likelihood of abnormal results for biomarkers related to anemia , kidney failure (between − 1.01 and − 1.19 p.p.), and arterial hypertension (between − 1.48 and − 1.64 p.p). The likelihood of abnormal levels of white blood cells and thrombocytes was negatively related to primary care coverage . The spillover effects were relevant for kidney failure and arterial hypertension, depending on the regional level. Although not sensitive to household coverage, diabetes mellitus was negatively associated with the state supply of primary care, and abnormal cholesterol levels did not present any relationship with ESF program coverage.The presence of spillover effects of ESF program coverage regarding these conditions reveals that the strengthening of primary care by increasing the household registration and the regional density of ESF teams is an efficient strategy to address important comorbidities.The online version contains supplementary material available at 10.1186/s12913-021-07329-9. The Family Health Strategy (ESF) program is the largest primary health care program in Brazil. Launched in 1993, the ESF program has, over the past two decades, spread gradually across Brazilian municipalities as part of a strategy to strengthen basic health care attention. The program is structured by health teams comprising one physician, one nurse, one auxiliary nurse, and four to six community health agents. Community health workers are responsible for periodic home visits to local residents to assess their general health conditions and, if necessary, to give them referrals to outpatient clinics, where the rest of the team members are based.Most of the existing literature on the topic assesses the impact of the ESF program , findingUp to 2008, every 5 years, the Brazilian Institute for Geography and Statistics (IBGE) included a special supplement on health in its Annual National Household Sample Survey (PNAD) with specific questions regarding the health of the population. From 2013 onward, this special supplement on health was converted into a broader separate survey called the National Health Survey (PNS). It contained more than 700 questions grouped into 21 themes, including children’s health, women’s and elderly people’s health, chronic diseases, oral health, eating habits, smoking habits, physical activity, health insurance coverage, search for medical services, hospital or outpatient clinics, household income, visits by community agents (including ESF program), and self-assessment of health, among other themes .11The PNS 2013 collected anthropometric measures  from household representatives and measured their blood pressure. A subsample of surveyed household representatives was assigned to attend a laboratory clinic to collect biological material (blood and urine) to be tested for some biomarkers. In total, 8952 adult individuals over the age of 18 years had their biological material collected. The following laboratory tests were performed ); and a Most of the studies with biomarkers and health interventions focus on high-income countries and cover a wide range of purposes and methods –32. This, anemia, thrombocytopenia, and arterial hypertension. Charts S1 and S2 in the Additional File The set of diseases and comorbidities assessed in this study was limited by the blood-based biomarkers and the exams contained in the laboratory tests, focusing on conditions that are sensitive to primary care . The folAs the laboratory results were made available separately from the PNS 2013 survey, it was necessary to adopt a procedure for merging both datasets to associate each biomarker level with the corresponding interviewed individual. To this end, an identification key was built based on the following information presented in both datasets: weight, height, sex, age, ethnicity, health self-evaluation, and level of education. The identification keys were complemented with specific questions  to maximize the key variability and the percentage of matches. This key proved to have a success rate of 99.8%: from the 8952 individuals tested, only 17 did not match.As the PNS allowed for the identification of the state and, if applicable, the metropolitan area that each surveyed household was in, it was possible to associate each laboratory result to the regional supply of the ESF teams.To do so, the measure of coverage was disaggregated into two direct dimensions and one indirect dimension, as follows:ESF registration: This is a binary variable (dummy) that equals one if the household was registered in the ESF program and zero otherwise, according to the individual’s answer in the PNS 2013. This variable is a measure of coverage and captures the direct effect of being assisted by an ESF team.ESF visits: This is the number of annual visits received by the household. The survey asked how often an ESF agent visited the household in the 12 months prior to the survey, and the number of visits was calculated according to the option chosen by the respondent. This variable was included to evaluate whether the intensity of primary care coverage had any relationship with the laboratory results.ESF program supply: This is the number of ESF teams by 10,000 inhabitants deployed to the metropolitan area or to the state in which the respondent dwelt in 2013 (source: Datasus [ Datasus ).The answers from the PNS allowed us to include three main sets of control variablesIndividual characteristics: sex, age, ethnicity, marital status, highest educational level (completed high school or completed college), individual health insurance, smoking status and practice of physical activity at least once a week.2); waist circumference; a previous diagnosis of the following conditions: chronic disease, kidney failure, heart condition, diabetes, cancer and/or high blood pressure; and if the individual was hospitalized in the 12 months prior to the survey.Individual health conditions: obesity , and the presence of piped water, electric power, sanitation, and/or garbage collection. These covariates aimed to control for socioeconomic characteristics that affect health. The descriptive statistics of both coverage and control variables can be found in Tables Additionally, the number of hospital beds per capita was included to control for the regional/local supply of health facilities (Source: Datasus ).The final number of individuals tested was below the actual drawn number due to logistic difficulties, which required a poststratification procedure. Sampling weights were calculated for use of the laboratory exam dataset, given the poststratification procedures by sex, age, ethnicity, and educational level according to large regions, from the total sample of the PNS . Fiocruzy is the binary variable equal to one if the result of the individual laboratory test is out of the reference range for the corresponding biomarker  is the cumulative of the standard normal distribution.The relationship between ESF program coverage and individual health was estimated through a probability model, in which the dependent variable presented the likelihood of an abnormal biomarker level. The probit model can be generically expressed as 1)::1\documeESF program registration and ESF visits); Specification II considered only individuals that were tested in metropolitan areas with household coverage and metropolitan ESF supply, as defined in the previous section; Specification III took into account all individuals that were tested with household coverage and the corresponding state ESF supply; and finally, Specification IV considered the full sample and household coverage (as Spec. I) but replaced the regional health facilities with binary variables that identified the state or, if applicable, the metropolitan area the respondent dwelt in, with the purpose of capturing the specific regional effects.Tables Table The spillover effect at the metropolitan level Table  was statExcept for diabetes mellitus and abnormal cholesterol levels, registration in the ESF program remained significant for all health conditions when the spillover effect at the state level was included Table , with maWhen the health facilities were replaced with metropolitan and state-specific effects Table , the negFinally, diabetes mellitus was the only comorbidity whose decrease in likelihood was robustly linked to health facilities because the effect of hospital bed density was negative and statistically significant at both the state and metropolitan levels. The other health conditions did not present a clear relationship with this variable, whereas anemia (in metropolitan areas) and arterial hypertension both presented a positive association.Leukopenia and leukocytosis can arise as a result of several diseases, and it is difficult to assess the channel through which the ESF program acts on the corresponding biomarkers. The results suggest that household registration is negatively correlated with the likelihood of observing such conditions. Because hospitalizations arising from acute infectious diseases, such as tuberculosis and syphilis, are avoidable through primary care services , one posThere is well-documented evidence of altered cholesterol levels in the Brazilian adult population, mainly among women, elderly people and less educated people . AdditioKidney failure and anemia are both more prevalent among elderly people and the low-income population in Brazil , 38. TheThe ESF program dynamics in the metropolitan regions seemed to be quite different than the average because individual coverage was not significant for all comorbidities within such regional constituencies, except leukopenia and leukocytosis at a 10% significance level. On the other hand, the spillover effects seemed to be negatively associated with kidney failure, anemia and high blood pressure in the metropolitan areas. The reasons for these results deserve deeper investigation. It is possible that the dynamics of the ESF in great urban clusters are different from those in smaller cities and include integrated actions with other agents that are not directly linked to primary care coverage.The number of annual visits was positively associated with thrombocytopenia, which was against the expected effect. Although a low blood platelet count is not preventable in most cases, it can denote/signal several health problems —a deficiThe spillover effect was strong for arterial hypertension, both at the metropolitan and state levels. Except in metropolitan areas, being registered in the ESF program was also important for avoiding hypertension, reducing the likelihood of abnormal biomarkers. This result is in accordance with recent evidence that the ESF program reduces mortality from complications of hypertension, including cerebrovascular diseases , 11.It is important to emphasize that, given the empirical strategy adopted in this study and the limitation of the datasets, a statistically significant result does not necessarily mean causality because the exposure and the outcome measures were taken at the same time (2013). It is wiser to interpret the results as statistically significant contemporary relationships. Nonetheless, the findings reveal important connections to guide public policies on primary health care.Unfortunately, the sample design of the PNS 2013 did not allow us to identify all the municipalities where the data were collected, but only the federation unit and the metropolitan region, if applicable. For a more refined study of the relationship between the density of ESF teams and the effects on individual health, it would be necessary to identify the location of each household; this would be an interesting next step for this research. Despite this limitation, this paper contributes to the field as a first investigation and could shed light on important policy priorities for primary health care in Brazil.Rather than having a unique objective, the Family Health Strategy has a set of multiple actions, as the most important primary care program in Brazil, from preventing infant mortality to referring patients for more complex procedures in outpatient clinics and hospitals. In this sense, it is not easy to draw objective policy conclusions from the results mentioned above. They reveal a complex combination of direct and indirect effects, with different linkages according to the type of coverage, the intensity of care and the dwelling region. Nonetheless, the results here allow us to state that increasing primary care coverage is a promising strategy to address important comorbidities in low- to middle-income countries. Moreover, the presence of indirect effects (spillover) suggests that health authorities should treat metropolitan areas in a different fashion, developing specific and coordinated actions among the municipalities that belong to them.Additional file 1.


To evaluate the impact of a paediatric radiological protection campaign, implemented in the emergency units of a healthcare provider network in Brazil. This campaign aimed to promote awareness among emergency department physicians, regarding justification of paediatric X-ray referrals for paranasal sinus, chest and CT exams, as a strategy to reduce exposure to ionising radiation.Frequency analysis of common paediatric imaging referrals from 19 emergency departments was performed for a 3-year period (2015–2018) to coincide with before, during and after the implementation of the radiation protection campaign. The campaign was multifaceted and involved dissemination of educational materials and imaging referral guidelines along with quarterly meetings with participating centres' leaderships. Additionally, patient dose cards were distributed to patients/carers. The Chi-Square test was used to examine the association between the type of examination and the patient's age group. Exact-Fisher test was performed to check for an association between participant engagement and the existence of the radiation protection committee.Referrals reduced by 25% following the campaign with no reports of misdiagnosis. Many referrals in the youngest age groups. In 15 units, a radiological protection committee was created to raise awareness and to create a multi professional team to communicate the risks and benefits of radiological procedure in children.The campaign resulted in a substantial reduction in radiological referrals while promoting a radiation protection culture. Simple education initiatives can contribute to savings in both finances and radiation doses, particularly important in radiosensitive cohorts. Educational strategies promote appropriate use of radiological exams.Individual patient dose cards are a tool to control children's exposure.Multiprofessional and parents’ awareness contribute to limiting unjustified radiological exams.The progressive increase in radiological referrals in recent decades, especially in computed tomography (CT), has been sizable, likewise in the paediatric population, mainly due to easy access, with high accuracy and quicker diagnosis, avoiding more invasive procedures , 2. MoreInternational campaigns on radiological protection –13 have This paper aims to raise awareness amongst healthcare professionals and service users about excessive exposure due to radiological exams. Radiation protection education strategies were implemented and a radioprotection campaign of the reasonable use of radiological examinations, in a private healthcare-associated unit in Brazil, performed in children assisted in the emergency service was evaluated.To evaluate the impact of a radiation protection campaign in Brazil, in the reduction of referrals of imaging procedures in a paediatric population.A retrospective and prospective quantitative multicentric longitudinal study in Brazil was performed in 46 voluntary units of a national healthcare system from June/2015 to May/2018 in different states of the country, recruited by convenience sampling. The study was approved by a university research ethics committee  and each participating unit filled out an adhesion and consent form for their participation.The authors, together with the operational and communication team of the national health care provider, developed resources including an individual dose card  with camAn engagement strategy was developed to raise awareness about the risks and effects of using radiological exams not necessary for diagnosis, to provide guides for use in the campaign, to instruct leaders to be multipliers in their services, and to collect data, through periodic quarterly meetings in person or by videoconference. This involved a multi-professional team  in the process of clarifying the campaign to the caregivers (parents), reducing pressure from parents and defensive medicine practices, seeking to provide support to doctors to strengthen the principle of justification before the imaging referral and using evidence-based recommendations. Success stories and difficulties of the participants were discussed during the meetings, with feedback from the analyses. Also, facilities representatives regularly reported perceptions of both professionals and parents during the campaign. Videos were developed and made available in the reception of emergency departments, along with banners and brochures explaining the campaign which were additionally placed in doctors' offices. The individual patient dose cards  were filThe specific recommendations of the guidelines on the campaign's awareness tools were disseminated at meetings and by email, based on the health surveillance rules of the Brazilian Health Authority , internaEach health care facility filled and sent, monthly, based on the unit's billing database, a standard spreadsheet with the number of radiological examinations and of attendance, performed at the paediatric emergency room, monthly data from the years before, during, and after the campaign and sent to the authors to analyse. Facilities were also asked to report any diagnostic errors arising from the rationalisation of radiological examinations. One data system analyst centralised the data collection.The collected data exams were chosen based on the most frequent radiographic exams  and all paediatric CT exams which were mostly brain with a minor percentage being abdominal and spine CT.The data were analysed using Stata Package version 16 . The confidence level was 95%. The variable chosen for analysis was the percentage of radiological exams requested by attendances, in three periods: June 2015–May/2016 (before the campaign); June/2016–May/2017 (during the campaign) and June/2017–May/2018 (after the end of the campaign). The Shapiro–Wilk test for normality was applied and the data of the index of exams requested/attendances were not normally distributed. The Chi-Square test was used to examine the association between the type of examination and the patient's age group. Exact-Fisher test was performed to check for an association between the participant engagement and the existence of the radiation protection committee. Wilcoxon paired tests were done with the index of referrals/attendances before and after the campaign. Incomplete data was omitted from analysis.Out of 123 facilities that attended the annual national healthcare system meeting, 46 units initially volunteered to take part in the project, 12 were excluded . Units that did not submit complete data also reported a lack of resources.Out of 34 units that participated, 15 (44%) have implemented a radiation protection committee, 12 (80%) of which submitted complete data. The Exact-Fisher test showed the significant association of participant engagement and the existence of a radiation protection committee , where the 19 participating units come from , 28, havThe ratio of the number of radiological exams per attendance performed in each unit was evaluated Fig. . PlottinIn the 12 months after the campaign, there was a reduction in the radiological exams at paediatric emergencies in the engaged units Fig. .Fig. 3ExThese reductions represented an overall reduction of 12,906 (25%) in the number of referrals for radiological exams in the attendances performed, after justification and implementation of the radioprotection campaign (Table p = 0.0065).The Wilcoxon paired test was done with the index of referrals/attendance before and after the campaign of each healthcare facility and showed a significant percentage reduction of exams (25%) (p < 0.01).The largest number of exams performed in the institutions evaluated was Chest X-ray (73%), and the largest age group requested was 0–4 years old (63%). The Chi-Square test showed this significant association between the type of exam and the patient's age group , and between September and November Fig. . The seaOf the 19 units that actively participated, there was a 25% reduction in the total rate of referrals for radiological exams in the emergency department post-campaign. The project corroborates the worldwide concern in encouraging educational activities and actions for radiological protection as well as guideline implementation. The paediatric radiological protection campaign is practical and effective and needs to be maintained with continuing education. The radiological protection committee created by the campaign was added to the strategic plan in the facilities. The introduction of the theme in medical undergraduate training and related radiology professions  could contribute to solidify the campaign as well as justify and optimise multidisciplinary actions , 8, 9.The initial decrease on the number of the exams to 0–4 years old from May to July in the beginning of the campaign was related to the mobilisation of the campaign by web meetings in March and April engaging the multi professional team including a manager, radiographers, radiologists, and paediatricians. The increase in the number of exams of Chest X-ray and Paranasal Sinuses X-ray referrals, mainly to 0–4 years old, between the months May and July (wintertime in Brazil) may be due to respiratory diseases prevalence in this time, and between September and November is probably due to the period preceding the population's summer vacation. Most respiratory diseases are self-limited, not requiring radiological exams, showing the need for justification and awareness of physicians and parents/guardians , 29.It observed, in general, many referrals for Chest X- Rays in the youngest age groups (53%). IAEA reinforces the importance to actualise physicians and radiologists about guidelines and clinical indications support.Participants reported voluntarily, during the quarterly meetings, that the main causes of overused referrals for radiological procedures, such as difficulty in accessing medical records in the care sector, pressure from parents, lack of institutional protocols and defensive medicine, lack of knowledge of parents and professionals about ionising radiation effects, lack of time in medical care, some of these causes resonate with common reasons identified by the WHO . LikewisRepresentatives of the units reported that the parents were surprised by the information about the cumulative effect of radiation and accepted if the resolution of the clinical examination was explained to them. Larson reported that communicating the risk of the exam to the parents before the exam is positive for their understanding and did not cause a refusal to perform it if it is justified by the requesting physician . In thisThe involvement of the multidisciplinary team in this approach has been relevant since the reception, where the parents first reported that they came to perform the exam, as if it was a "photograph", without biological effects. Radiation protection campaign helped to clarify to physicians and patients the risks and benefits of radiological exams , and itsThe facilities were asked to create Radiation protection committees as part of the campaign. They were created in 15 units, with more significant results than the others and were incorporated in each health care facility. The units with radiation protection committees were more engaged in the campaign, likely due to being more organised and prepared by the multi-professional team. It reinforced that communication is especially important to change the culture and promote good practice in medicine . These cA pioneer radioprotection pilot project, applied in a private hospital in Brazil , 35, wasThis project encountered many challenges which deserve mentioning. Firstly, the scale of the project arising from the multicentre design, continental dimensions of the country and different organisational structures and cultures between units, required considerable planning and organisation with regular meetings and communication needed to maximise engagement. Secondly, the lack of national regulation on justification of radiological examinations coupled with the requisite of creating new local radiological protection committees, meant the project relied heavily on voluntary participation of motivated professionals. Finally, as with any such projects of scale, operating cost was not trivial, but was well compensated by savings in resources and radiation burden from the demonstrated reduction in imaging referrals.Throughout the present study, we emphasised to imaging professionals that if the radiological examination is necessary, especially tomography, dose optimisation recommendations should be followed .The limitations of the present study primarily included non-probabilistic sampling; and resourcing difficulties which led to the withdrawal of participants, who were unable to support the campaign. One motivation for implementing the campaign was their integration into quality programs. In the quarterly meetings or e-mail communication, no diagnostic errors were reported by the facilities, during the study period despite regular reminders. It is possible however that such incidents may have occurred but were either not detected or reported. Formal quantitative checking of a sample of medical records would have been useful to verify this, although due to resource constraints was not performed here.To enable culture change the continuation of the project is important to keep it alive in the institution, professionals, and the population. The radiation risk and benefit communication, recommendations and the tools to the stakeholders clarified the purpose of the campaign and as they are close to patient's care, they are an important piece in the effectiveness of the process.The campaign improved the awareness that may impact on justification of imaging referrals for children aged 0–12 years, especially to the 0–4 years old group, which are the cohort with the most risk of radiation effects, contributing to the patient's security.The study can be generalised to other emergency services if it follows the campaign methodology, its evaluation, and permanent education aiming at the continuity of the new behaviors.The campaign resulted in a substantial reduction in radiological referrals while promoting a radiation protection culture in the department. Simple education initiatives can contribute to both financial and radiation doses savings, particularly important in radiosensitive cohorts. Continuous education is especially important to change the culture of overuse, as well as information and communication to patients and carers about the benefits and risks of ionising radiation.The group has done other initiatives in training and education with medical students and residents, reinforcing a National Radiation Protection Committee, and establishing Diagnostic Reference Level for CT exams in Brazil and is going to return to the justification campaign next year. It is recommended to continue to organise an annual meeting post campaign with the participants and future studies could investigate the ideal recommended period between campaigns. Further research including patients' perceptions on physician communications about radiological exams, as well as, about ionisation radiation exams awareness, would help to understand populations feelings, values, and knowledge about the theme, helping to create strategies to change the culture. A similar adult radiological protection campaign will be encouraged in the future in Brazil.The project implemented a successful campaign  in the emergency department, through educational tools, radioprotection implementation guidelines and recommendations to improve patient’s safety and medical practice quality.


Optic flow can be defined as a vector field of the apparent motion of objects, surfaces, and edges in a visual scene caused by the relative motion between an agent and the scene. In the last century Gibson developed the ecological approach to perception and action in which this optic flow provides an agent  all the information they need to navigate safely in cluttered environments. Gibson’s framework has already proved to be relevant in addressing issues related to the control of human displacement and by offering the robotics community a framework for carrying out new generations of studies. We would like to argue in this contribution that the ecological approach to perception and action, taken as a whole, provides powerful theoretical and methodological tools allowing the entomologist community to: (i) take a critical look at the research carried out to date, (ii) develop new experimental protocols, and (iii) raise new questions beyond the scope of current investigations. After a concise literature review about the perceptual control of displacement in insects, we will present the framework proposed by Gibson and suggest its added value for carrying out research in the field of entomology.To date, numerous studies have demonstrated the fundamental role played by optic flow in the control of goal-directed displacement tasks in insects. Optic flow was first introduced by Gibson as part of their ecological approach to perception and action. While this theoretical approach (as a whole) has been demonstrated to be particularly suitable for the study of goal-directed displacements in humans, its usefulness in carrying out entomological field studies remains to be established. In this review we would like to demonstrate that the ecological approach to perception and action could be relevant for the entomologist community in their future investigations. This approach could provide a conceptual and methodological framework for the community in order to: (i) take a critical look at the research carried out to date, (ii) develop rigorous and innovative experimental protocols, and (iii) define scientific issues that push the boundaries of the current scientific field. After a concise literature review about the perceptual control of displacement in insects, we will present the framework proposed by Gibson and suggest its added value for carrying out research in the field of behavioral ecology in insects. Over the last eighty years, it has often been shown that flying insects rely on optic flow to perform various locomotion tasks ,2,3,4,5.Terrain-following task: The ventral part of the optic flow is useful to follow the ground [Drosophila flies establish an altitude set point on the basis of nearby horizontal edges and tend to fly at the same height as such features”. A similar conclusion was drawn by David [e ground ,15,16,17e ground  proposede ground  proposede ground  “found tby David  about alCentering and wall-following tasks: The lateral/frontal parts of the optic flow are useful to center in a narrow corridor by balancing the lateral parts of the optic flow , or to oneybees , in bumboneybees ). Kirchnoneybees  suggesteoneybees  found a oneybees  found thoneybees  found thSpeed adjustment task: The bilateral  part of the optic flow is useful to adjust flight speed [ht speed ,21,26,27ht speed ). Srinivht speed ,29. Bairht speed  found inLanding task: The ventral part of the optic flow can also be regulated by honeybees to land [ to land ,26. Srin to land  conclude to land  also con to land ,5,9.As stated previously, most of the studies cited in this first section highlight the central role played by optic flow in the control of navigation tasks in insects. A close inspection of these studies demonstrates significant disparities between the terms used when referring to the same concepts or entities see . It alsoIn the last century, through his ecological approach, Gibson provided a new conception of the links between perception and action. This new approach resolutely broke with the prevailing (cognitive) theories of perception, and has been made accessible through three major contributions  between an agent  and the environment in which it operates, and (ii) between perception and action. According to the first postulate (i) the multiple interactions between a given agent and their environment shape  the perceptual-motor mechanisms used by the agent to move through their environment, so that the appropriate level of analysis to study these mechanisms is at the scale of the agent-environment system. According to the second postulate (ii) perception and action are part of the same cycle without any hierarchy. Contrary to the traditional view in which perception subserves action, Gibson described a circular relationship between perception and action in the sense that a movement gives rise to perceptual information which, in turn, allows movement to be adjusted and so on and so forth.In accordance with ontological foundations see  of the tvisual control of displacement, based on optic flow. However, it is worth mentioning that the same reasoning holds for the other perceptual systems  of an agent who wishes to intercept a moving target approaching along a parabolic flight. The only thing the agent has to do, assuming they are sensitive to the perceptual information, is to move appropriately so as to continuously cancel the optical vertical acceleration of the target [For example, when an agent moves forward, the optic flow expands radially from a stationary point, called the focus of expansion (FOE) , which ce target ,46. Intedetected the invariant specifies the state of the system . Given the fact that invariants are, by definition, unequivocally related to the state of the AES, detecting an invariant gives access to the state of the system; in other words, once e.g., in . To comepothesis  that movtomology ,48,49,50heuristics from invariants is to refer to them, respectively, as low order and high order variables . To clae.g., in  for furte.g., in ). This me.g., in . It coule.g., in .The experimental agenda that must be implemented when one wishes to take an interest in the issue of goal-directed displacement control within the framework of ecological psychology is as follows: analyzing task constraints, identifying the informational landscape, and specifically manipulating an optical variable.Analyzing task constraints. Although it may initially seem trivial, the departure point of the research is defined by a close inspection of the constraints characterizing the task at the scale of the AES. Because optic flow contains potentially high order variables allowing access to the state of the AES, identifying the relevant property of the agent-environment system (PAES) is of paramount importance in a search of these high order variables. A couple of examples will clarify our point. In heading tasks, e.g., when making your way through a cluttered environment, the relevant PAES could reside in the direction of travel in relation to the surfaces of the environment. In interceptive tasks, i.e., when interacting with stationary or moving surfaces of the environment, the temporal proximity of the target could constitute the relevant PAES. In terrain following tasks, the PAES could reside in the flight height maintenance in reference to the ground.Identifying the informational landscape available. Once the PAES has been identified, the information landscape allowing access to it can be described/formalized. Citing the three examples used in the previous section, the high order variables that could specify the state of the AES could be, respectively, the FOE (heading task), usly see , the infusly see . It is iManipulating an optical variable. Once the informational landscape available when performing a given task has been clearly identified, the ideal strategy is to implement an experimental stratagem allowing for a specific manipulation of an optical variable  in the perceptual flows when they perform similar tasks.While the literature contains numerous results which demonstrate the major role played by optic flow in the control of displacement in insects, the conceptual framework provided by Gibson see  allows aTerrain-following tasks: The studies mentioned [entioned ,15,16,17Centering task: The centering behavior observed in many insect species [ species ,21,22,26 species . This grSpeed adjustment task: The studies reviewed in Landing task: Regardless of the fact that several high order variables can be used to control landing tasks, the study by Srinivasan [inivasan  is interAs Gibson’s framework is not species-specific, it is easily adaptable to carry out research in insect behavior. It enables us to think in terms of the available informational landscape to better design experimental protocols and setups. It also allows us to focus on the variable(s) leading to the most parsimonious strategy when performing a goal-directed task. Keeping these ideas in mind, a new reading of research focusing on the role of optic flow in insects becomes possible.Drosophila melanogaster though tunnels which allowed an easy manipulation of lines on the side walls, whose height could be changed during and between trials. Despite the fact that the ground was textured so as to supply easy access to optic flow velocity (and its rate of change), flying Drosophila preferred to follow these prominent lines. At first glance this result may seem surprising, as flying Drosophila seem to prefer using a low order variable (line tracking) instead of a high order variable (the rate of change in optic flow velocity). When performing this type of task, the line provides a low order perceptual variable as line following does not in any way guarantee that altitude will be maintained. This perceptual strategy can be extremely dangerous in an ecological context but allows the flying Drosophila to perform the task easily in the highly constrained environment used in the experiment. While demonstrating the extraordinary flexibility of insects, this result should urge caution; the results obtained in a very constrained environmental setup are not necessarily generalizable as such to other ecological contexts. That is the reason why 3D environments should be preferred over 2D environments when trying to identify the perceptual variables underlying the control of insects flight. Insects’ perceptual systems have evolved and adapted through interactions with their 3D environments so that the 3D properties of the environment should be preserved as much as possible [When examining studies focusing on the identification of perceptual variables involved in flight control, it is essential to clearly differentiate low order and high order variables. Perceptual strategies relying on high order variables could be prioritized by insects given that they are based on a precise access to the state of the AES and so provide robust strategies leading to safe behaviors. However, and counterintuitively, in some cases low order variables are preferred to high order variables ,35. Strapossible ,49,61,62The issues related to the identification of the perceptual variables involved in the control of landing tasks by insects have also deserved a lot of interest in recent years ,66,67,68al value . These pe insect  and the variable . The onlMegalopta genalis. The insects were trained to move along a hallway whose walls could provide either a strong optical velocity (thanks to a checkerboard pattern) or weak optical velocity . Contrary to the authors’ expectations, Megalopta genalis was shown to exhibit more variance in their centering response in the presence of checkerboard patterns in comparison with the other condition. Although this result could initially appear counterintuitive, a deeper analysis of the informational landscape provided to the insects in the two conditions sheds a different light on this issue. While the checkerboard pattern allows a centering behavior based on the use of motion parallax  would also use a combination of perceptual variables in the control of altitude. Although the terminology used by the authors is based on a theoretical framework other than Gibson’s (the authors evoke “a combination of three sensory-motor reflexes”), the results of their study support the thesis of the joint use of different perceptual variables by the insect.We may wonder if there is any reason to believe that evolution has caused insects to develop perceptual processes distinct from those of humans. In other words, while many experiments provide some fuel for the idea that humans use several perceptual variables, when available, in combination ,70,71, dThe idea of a combination of different perceptual variables is very attractive because it gives a certain robustness to the perceptual process. The agent can theoretically adapt its flight to a degraded environment and/or to a momentary absence of certain variables if other variables are available. This new conception of the perceptual process paves the way for a new generation of studies focusing on the underlying combination process. In the case of two high order variables being available, is there necessarily a priority between them and, if so, on what basis? Does the nature of the environment in which the agent is operating affect the prioritization of the perceptual variables used? In any case, it will be necessary in the future to focus on the combination processes in order to identify the prevailing principles and ideally to formalize them.The abundance of perceptual variables mentioned in the previous section provides agents with perceptual degrees of freedom potentially allowing them to rapidly adapt to unexpected changes in their surroundings, and also to optimize their behavior across repetitions in the longer term. The two processes (adaptation and learning) could be interesting in the domain of entomology, considering the extraordinary ability of insects to move safely in cluttered environments. Here again, to our knowledge, these processes have received little attention in the domain of visual ecology in insects, in comparison with the colossal number of studies dedicated to these processes in humans.The studies designed to examine the adaptation process in humans generally used a dedicated three-step methodology designed to: (i) examine the behavior in a control condition, (ii) examine the kinetics of the adaptation process following a perturbation, (iii) return to the control condition so as to assess the presence of a post-effect. Examining the kinetics of the adaptation process in insects following, as an example, a severe degradation of the perceptual support available could be worth considering . This kiHowever, it seems to us that particular attention should be paid to the study of the processes underlying the  learning of navigational tasks in insects. According to the tenets of ecological psychology, perceptual learning is a matter of educating the attention of the agent, through training, towards the relevant perceptual variable. A number of experiments in humans have demonstrated that learning is accompanied by a change in the perceptual variable(s) used preferentially, with a shift from lower order variable(s) to higher order ones ,72 Figu. The cenThe stated ambition of this review is to promote the conceptual framework provided by Gibson  to addre


Autism Spectrum Disorder (ASD) is a complex childhood onset neurodevelopmental disorder that has become the fastest growing developmental disability. Due to the increased demand for diagnostic assessments and subsequent increased wait times, standardized screening as part of regular clinical practice is needed. More specifically, there is an important need for the development of a more streamlined screening tool within an existing assessment system to identify those at greatest risk of having ASD. The current study utilized data from ~17,000 assessments obtained within the province of Ontario, based on the interRAI Child and Youth Mental Health (ChYMH) and Child and Youth Mental Health and Developmental Disability (ChYMH-DD), to develop a scale to identify children who have a higher likelihood of having autism. The scale was then tested on a trial population with data from the interRAI Early Years instrument. Further analyses examined the predictive validity of the scale. The Autism Spectrum Screening Checklist (ASSC) was found to be a good predictor of ASD with a sensitivity of 0.73 and specificity of 0.62, at the recommended cut-point of 2+. The results were consistent across several age ranges, specifically from 2 to 21 years of age. The ASSC scale provides an initial screen to help identify children and youth at heightened risk for autism within larger populations being assessed as part of routine practice. The main goal for the development and implementation of the ASSC scale is to harness the power of the existing interRAI assessment system to provide a more efficient, effective screening and referral process. This will ultimately help improve patient outcomes through needs-based care. Autism spectrum disorder (ASD) is a complex, lifelong, neurodevelopmental disorder that is characterized by impairment in social communication and the presence of restricted repetitive behaviors , 2. ASD Autism is one of the most common childhood onset neurodevelopmental disorders. It is estimated that the current prevalence rate is ~1–1.5% of the world's population . With reVarious factors account for the more than 2 year difference between parents noticing the early signs of autism to receiving a diagnosis. Some of these barriers include time-consuming evaluations as well as a lack of providers who are able to administer the diagnostic assessments , 22. OthFinally, an overarching barrier to early identification and diagnosis is ineffective care pathways . ImproveThe aim of the present study was to develop a methodology for identifying children who are at greatest risk of having autism within the children's mental health system in the province of Ontario, Canada. Since no effective, easily implemented screening method exists, an effort was launched to develop a new scale for identifying individuals who have an increased likelihood of autism. The Autism Spectrum Screening Checklist (ASSC) was created to assist service providers in determining whether a toddler, child or adolescent is at higher risk of having ASD. This scale is embedded in an assessment-to-intervention system that is already used as standard practice across Ontario in most child and youth mental health agencies to foster effective, evidence-informed care pathways. The aim of this study is to describe the development of the ASSC scale.Data came from assessments of children and youth receiving mental health services in Ontario, Canada. The derivation sample came from individuals aged 4–21 years assessed with the Child and Youth Mental Health (ChYMH)  or the CThere were 16,955 individuals in the derivation dataset, using the first assessment if an individual had more than one. The mean age was 11.95 years (SD 3.50) and 55.9% were male. There were 724 individuals in the trial application dataset of 2 and 3 year-old children, where the mean age was 2.48 (SD 0.52) and 68.8% were male. To examine predictive validity, a sub-sample of 318 individuals was used from the original derivation sample. The mean age was 11.02 years (SD 4.00) and 64.5% were male.Assessors completed a 2.5 day training of each of the three interRAI Child and Youth instruments: ChYMH, ChYMH-DD, and the interRAI Early Years. The trained child/youth mental health professionals included psychologists, nurses, psychiatrists, speech and language therapists, child and youth workers, developmental social service workers, and social workers. All available sources of information are utilized to complete the assessment .Secure web-based software was utilized to record assessment information, requiring responses of the proper form for all essential items before the record can be authorized as complete. Before making the data available for analysis, personal identifiers were removed. Western University's ethics board granted approval for the secondary analysis of data collected in various agencies throughout the province of Ontario (REB #106415).interRAI Early Years is a new instrument within the interRAI child/youth suite and has been designed for young children under the age of 4 years who are referred for assessment due to mental health, relational and/or developmental concerns ; for our dependent variable, we collapsed a diagnosis of autism of any importance to be one, otherwise zero.A list of potential explanatory variables was generated. All items in the ChYMH or ChYMH-DD instruments were considered by a clinical expert for their potential association with autism, and seven candidate items were selected . Furthermore, bivariate associations between an autism diagnosis and other items in the derivation dataset were used to identify a small number of additional items that offered statistical strength. However, these additional items were not pursued, either because they were not available in the interRAI Early Years assessment instrument, or they were considered problematic for use with very young children . The seven candidate items were all binary. The last 3 days was the reference timeframe.Using multivariable logistic regression, these seven items were tested together to assess their ability to independently predict an autism diagnosis and to remove non-contributing items. A series of tests using the count of retained items was then applied, with logistic regression of the count of the items to assess goodness of fit, and correlation analysis to provide a Cronbach alpha value for the individual items to inform internal consistency of the contributing items. Sensitivity and specificity for different summed scale cut-points were considered. The selected scale was tested in a trial population using the interRAI Early Years cases where it could be calculated. Furthermore, using a sample of 318 ChYMH or ChYMH-DD assessments, the ASSC scale was calculated, and longitudinal analyses related to predictive validity were conducted. Specifically, the sample included individuals for whom provisional diagnostic assignment  had not been completed at the time of initial assessment, and a follow-up assessment within 365 days where it had been subsequently done. This allowed the scale to operate more like a predictive measure where a child or youth not yet subjected to diagnostic assignment at the time the scale is assigned is subsequently diagnosed, either positively or negatively, for autism.The seven candidate items and their distribution by autism diagnosis are summarized in The five-item version was ultimately selected based on it having more parsimony than the six-item version, and the best internal consistency of the three options. However, all three versions are quite similar in performance with strong goodness of fit; c-statistics are >0.82, which is considered to be a strong result .The five-item summative scale was applied to the interRAI Early Years assessments, where 9.5% of the cases had a diagnosis of autism; the results are summarized in Using a sub-sample from the derivation dataset, the predictive validity of the ASSC score was investigated. Distribution of the summed items and percentage with autism diagnosis at follow-up are provided in High risk for ASD was predicted by five contributing items, namely narrowly restricted range of interest, excessive preoccupation with activity or routine, lack of social/emotional conventions when socializing, excessive or unusual reaction to sensory stimuli, and difficulty adapting to even minor change. The contributing items are all well-known signs and symptoms of autism . MoreoveBased on the findings, ASSC provides an empirically based score that may be used to identify toddlers, children, and youth who present with signs and symptoms that are known to increase one's likelihood of being diagnosed with ASD. Findings indicate that the ASSC is a good predictor of autism and has reasonable sensitivity and specificity at the designated cut-point of 2+. As a result, it will allow service providers to make more systematic evaluations in determining whether an individual is at greater risk of having ASD, which ultimately helps facilitate prioritization and triaging.While the ASSC scale has reasonable sensitivity (0.73) and specificity (0.62) at the recommended cut-point of 2+, its PPV at this level is 0.367. This means that ~37% of children and adolescents above the designated cut-point will likely be diagnosed with autism. Although this percentage seems somewhat low, there are a couple of important considerations to take into account. First, both PPV and NPV depend on prevalence, with PPV being directly proportional to the prevalence of autism. This is exemplified in the current study whereby as prevalence of autism increased, for example, from within the trial population dataset to the longitudinal dataset , the PPV also increased . Therefore, utilizing NPV and PPV when prevalence is low should be done with caution, given that one would expect a low PPV. Second, other studies utilizing administrative datasets from real world settings to screen for autism have also reported low PPV  on previously validated instruments –55.Service providers who have completed the interRAI ChYMH, ChYMH-DD, or interRAI Early Years assessment can obtain the ASSC results automatically from the software in which the scale is embedded. It is important to emphasize that the results are meant to assist healthcare providers in identifying how to best support each child's care planning needs based on the ASSC score. Thus, the scale is not meant to be used as an automated decision-making system, without any clinical judgment, but in conjunction with all of the other information collected during the assessment process. Lastly, it is important to always consult with the individual child and the family to ensure that their strengths and needs are considered throughout the process.Subsequent assessment and care planning steps will be determined, in part, by whether the child's ASSC score falls within the upper or lower range. For example, if the child's score falls within the lower range, it is advised that the healthcare clinicians discuss whether the ASSC score is fitting in light of all of the information that has been gathered. However, if the child's score falls within the upper range, it is advised that the healthcare clinicians consider the individual to be at higher risk for having autism and conduct an in-depth evaluation specifically designed for this sub-population. Ultimately, the key advantage of implementing the ASSC scale would be that toddlers, children, and youth with higher levels of risk should be receiving a timelier comprehensive follow-up evaluation compared to those with lower-level risk. Notably, future research will be conducted to assign ASSC scores to ascending risk categories to determine what labels are best utilized for specific scores on the scale , as well as how they relate to clinical referrals and specific actions that are recommended.It is important to note that diagnosing autism is a complex process and requires multiple steps, such as: (a) reviewing records; (b) interviewing parents, family members, and other caregivers; (c) assessing for core features through interactions with the child to examine social interaction and communication abilities; (d) utilizing ASD-specific diagnostic tools; and (e) conducting a physical examination and additional investigations . Given tWhile the ASSC scale provides an initial screening as opposed to a diagnostic tool, it still has significant utility for individuals, families, clinicians, and the system as a whole. For example, this effective screening method could reduce wait times, allowing for more efficient referrals, and thus quicker access to health, social support, and education services. Notably, earlier access to intervention can foster appropriate development in social interactions, communication, and behavior . TherefoFamilies will also benefit from implementation of the ASSC; more specifically, utilizing an existing instrument that is already in use across most mental health agencies can facilitate expedited triaging resulting in a reduction in the waiting period for families. Such an approach would not only reduce the stress level of the family when navigating the service system, but also foster an increased likelihood of more appropriate referrals to specialized autism services. Research has shown that most families experience the “diagnostic odyssey” as overwhelmingly negative due to long waiting periods. For example, Lappé et al.  found thWith respect to clinical utility, the ASSC provides an opportunity for initial screening for children and youth who are referred for mental health services. Consequently, children who are at greater risk of having autism can be identified through this initial screening approach, resulting in reduced cost and time on behalf of the clinician, agency, as well as the client and their family. Additionally, if a child is determined to be at high risk of having autism and is eventually referred for a more comprehensive diagnostic assessment, a substantial amount of background information will already be available from the interRAI assessment, thereby reducing assessor burden. Interestingly, one study examined factors influencing wait times for an ASD diagnosis and found that the most important predictor of assessment duration was the amount of information available in relation to the child prior to the assessment , exempliAt the systems level, comprehensive assessment of ASD is associated with more healthcare costs and resources. Proper screening and triaging utilizing the ASSC can aid in more expedient and efficient use of resources. Having said that, use and utility may differ depending on the resources available as well as the challenges of operationalizing services that are more or less precious. For example, trading off wait times for follow-up diagnosis may look different if a child is seeking services in an urban center in comparison to a remote area or developing nation.In addition to individualized care planning, the ASSC scale can also provide comprehensive, standardized data across large catchment areas, which: (1) enhances early identification of children with possible autism across the system and (2) provides the ability to examine the prevalence of these symptoms across jurisdictions. Furthermore, this streamlined screening method may help decrease disparities in access to diagnostic services, providing more equitable care at the population-level . In addiWhile the current study has many notable strengths, it also has some limitations. For example, given that the present study was not conducted within the controlled setting of a rigorous research study, reliance on broad signals related to associations between items and an autism diagnosis is required, thereby limiting psychometric precision. As such, these results suggest that augmented assessment approaches are needed to reduce disparities to enhance early detection . To imprAnother limitation is that the results of the study may not be generalizable to a community-based sample. This is due to the fact that the young persons assessed were receiving services from inpatient and outpatient mental health agencies. Therefore, future research will explore whether the results of the current study are similar when the young persons assessed are comprised of a community sample. Furthermore, future research will also examine the scale's utility at different cut points once further implementation of the instruments are done both nationally and internationally.There is an overwhelming call for an evolution of the systems of care built to identify those with ASD, as the current wait time to receive a diagnosis is unacceptable to the individuals and families we serve , 22, 68.The original contributions presented in the study are included in the article/Supplementary Material, further inquiries can be directed to the corresponding author/s.The studies involving human participants were reviewed and approved by Western University's ethics review board (REB #106415). Written informed consent from the participants' legal guardian/next of kin was not required to participate in this study in accordance with the national legislation and the institutional requirements.SS and JP developed the analytical strategy. JP performed the statistical analysis. All authors contributed to the formulation of the ideas presented in the study, provided critical feedback to the manuscript, and were involved in the writing and reviewing of the final manuscript.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. The handling editor JF declared a past co-authorship/collaboration with one of the authors SS.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.


Novel electric air transportation is emerging as an industry that could help to improve the lives of people living in both metropolitan and rural areas through integration into infrastructure and services. However, as this new resource of accessibility increases in momentum, the need to investigate any potential adverse health impacts on the public becomes paramount. This paper details research investigating the effectiveness of available noise metrics and sound quality metrics (SQMs) for assessing perception of drone noise. A subjective experiment was undertaken to gather data on human response to a comprehensive set of drone sounds and to investigate the relationship between perceived annoyance, perceived loudness and perceived pitch and key psychoacoustic factors. Based on statistical analyses, subjective models were obtained for perceived annoyance, loudness and pitch of drone noise. These models provide understanding on key psychoacoustic features to consider in decision making in order to mitigate the impact of drone noise. For the drone sounds tested in this paper, the main contributors to perceived annoyance are perceived noise level (PNL) and sharpness; for perceived loudness are PNL and fluctuation strength; and for perceived pitch are sharpness, roughness and Aures tonality. Responses for the drone sounds tested were found to be highly sensitive to the distance between drone and receiver, measured in terms of height above ground level (HAGL). All these findings could inform the optimisation of drone operating conditions in order to mitigate community noise. A scenario with several drones (whether manned or unmanned) flying over cities and rural areas is now more likely than ever. To start with, there is a myriad of potential uses, from recreational to parcel delivery and even surveillance and law enforcement. There are substantial environmental and societal benefits associated with the wider expansion of the drone sector. For instance, medical deliveries to reduce waiting times  or reducThe noise emission of drones and isolated drone propellers have been extensively studied ,12,13,14Schäffer et al.  carried Aeq-related nor even more sophisticated metrics, such as the effective perceived noise level (EPNL) [AE) was not able to account on its own for the difference in annoyance between drones and road vehicles. In their study, for a same value of LAE, drones were found to be more annoying than road vehicles. In fact, drones were reported to be as annoying as road vehicles with a 5.6 dB higher LAE. Torija et al. [Aeq metric does not account for the particular sound features related to drones, and that these particular features highly influence drone noise reported annoyance. Current regulation of drone noise is solely based on A-weighted sound power level , which, as suggested by Torija and Clark [Current evidence suggests that drone noise annoyance highly depends on loudness-related metrics ,15,16. Hl (EPNL) . Christia et al.  also found Clark  might noThe aim of this paper is to investigate the perception of drone noise under controlled laboratory conditions in order to propose noise metrics for effectively assessing human response to drone noise. This research is framed within the perception-driven engineering approach, where sound quality metrics (SQMs) provide an accurate assessment of how the human auditory system responds to key sound features ,24. GwakThe structure of the paper is as follows. Aeq) [Aeq,16h. At a vehicle level, broadband frequency-weighted sound pressure levels are used for aircraft noise assessment. These metrics include the maximum A-weighted sound level  and the A-weighted sound exposure level (LAE). LA,max is a common metric to assess sleep disturbance [AE is numerically equivalent to the total sound energy of an aircraft overflight and therefore is very useful to compare total emission of different types of aircraft under different operating and payload conditions. However, these metrics do not account for other important features for noise annoyance, such as tonality [The impact of aircraft noise on communities is mainly assessed with exposure metrics related to A-weighted energy equivalent sound pressure level (LAeq) ,26. Examturbance . LAE is tonality ,29. The tonality  and is ctonality . This metonality . The PNLtonality . The PNLtonality , might ntonality .SQMs provide an accurate representation of huma hearing perception ,33. The In addition to drone noise, as described in A database of 44 drone sounds were carefully selected for the subjective experiment in order to assess perceived annoyance, loudness and pitch. The criteria for selection was to include sounds encompassing a wide variety of loudness level and other key psychoacoustic parameters for drone noise, including temporal and frequency characteristics (see ). The drAeq,4s of the drone sounds ranged between 37 dB and 71 dB. The full list of the 44 drone sounds with associated characteristics can be seen in Aeq,4s between sounds from the same drone type with identical weight and HAGL might be attributed to small variations in operating and meteorological conditions, such as small differences in vehicle speed and different rotor rotational speeds to maintain vehicle stability under different wind profiles. It should also be noted that the DJI Phantom 3 was tested with varying payloads  of 2 to 60 m. The La et al. ).As mentioned above, the drone sounds described in Temporal and spectral characteristics of drone noise have been found to be highly influenced by the type of vehicle operation and meteorological conditions ,23. As tAeq,4s targets, a calibration process was designed. The control of the LAeq,4s of the test sounds is especially important when assessing the effect of operational factors, such as type of operation, vehicle weight and HAGL (and consequently loudness) on perception responses. The calibration setup included a class 1 BSWA308 sound level meter, a Bruel and Kjaer head and torso system (HATS), Norsonic front end type 336 microphone pre-amp, M-Audio M-Track 2X2M audio interface, AKG k 501 headphones, Audio Quest Dragonfly Red USB sound cards (24 bits 96 kHz) and a mainstream laptop for stimuli playback and recording. The calibration setup is presented in In order to set the sound pressure level of the drone sounds used in the subjective experiment to the LAeq,4s  . An inteThe online experiment was accessible via personalised URL links in order to maintain anonymity and security between participant data. The online experiment was advertised on social media and to the staff and students at the University of Salford. Each person interested in participating was provided with a personalized URL link and a participant ID. Overall, 89 participants completed the online experiment in part, with 49 of them completing the full test . Therefore, the responses of the 49 participants who completed the full test have been used for the analysis of this paper. The participants were instructed to complete the test in a quiet, distraction-free environment and to use high-quality headphones.Each drone sound was presented individually to the participants. Once each drone sound was presented, the participants could listen to it as many times as required. Responses were then given using a set of sliders in the interface. Once the participants were satisfied with their responses, they could progress to the next stimulus, until the whole set of 44 test sounds were heard and assessed. The order of the stimuli for each participant was randomised.Prior to the commencement of the experiment, each participant went through a pseudo-calibration stage in order to adjust the level of the UAV stimuli. Since the experiment was online and accessed remotely by the participants, the playback hardware used by each participant was unknown and highly likely to vary. This would lead to a variance in the playback quality and level of the stimuli between participants. To try to counter this, the participants were presented with the loudest and quietest UAV stimuli from the experiment and asked to adjust their playback volume so that the loudest stimulus was at a comfortable level and the quietest stimulus was still audible. Once the participant had appropriately adjusted their system playback level, they were asked to not adjust it for the remainder of the experiment. In addition to this, before starting the experiment, the participants were asked to match the sound levels of a series of tones in order to understand their frequency sensitivity . A channel checking stage was also included to ensure that stereo playback was used. All 49 participants considered in this research paper appropriately passed these pseudo-calibration stages. In order to analyse the consistency of participants’ responses and the potential effect of using different sound reproduction settings (due to the experiment to be online), a statistical analysis was carried out . The second experiment (not reported here) will investigate the effects of drones on the soundscape in which they are operating.To quantify the spectral and temporal characteristics of the drone-sound stimuli, the HEAD Acoustics ArtemiS Suite 12.5 software was used to calculate a series of SQMs  was implemented to give an initial insight into the relationship between each SQM and PNL and the perceived responses of annoyance, loudness and pitch for each drone sound stimulus. A multiple linear regression (MLR) analysis was also carried out to further determine the main contributors for the perceptual variables assessed in this paper. A forward stepwise-regression method  was implemented.As the experiment was carried out online, with the participants reproducing the test sounds with different reproduction settings, two statistical tests were implemented to assess consistency between participant responses: (i) a Kendall’s W test to investigate the concordance in perceived annoyance, loudness and pitch for each drone sound between participants see ; and  was also calculated as the standard deviation divided by the mean in order to check consistency in participants’ responses. As can be seen in The aggregated participant responses for each flyover drone sound were used to investigate the relationship between perceived annoyance, loudness and pitch with HAGL. As it can be seen in In order to further investigate the relationship between different psychoacoustic factors and the perceived responses for the flyover drone sounds tested, a correlation analysis was carried out. Zero-order and partial correlation coefficients controlling for HAGL were calculated between PNL and the SQMs  and perceived annoyance , perceivp ≤ 0.05) with perceived annoyance and loudness, respectively, both zero-order and when controlling for HAGL. This suggests that the different HAGL for the flyover drone sounds did not have any influence in the relationship between PNL, loudness and sharpness and responses of perceived annoyance and perceived loudness. For the case of perceived pitch  with both perceived annoyance and perceived loudness. Responses on perceived annoyance and loudness seem to have a significant association to PNL, loudness and sharpness.After investigating the correlation between PNL and the SQMs considered and the perceived responses for flyover drone sounds at varying HAGL, a bivariate correlation analysis was carried out with the whole set of test sounds. As seen in p ≤ 0.05) with perceived pitch. For this particular case, sharpness has the highest correlation with perceived pitch, although contribution from the metrics listed above is observed as well.An important finding, as shown in The linear relationship between predictors and dependent variables was verified in The value of the variance inflation factor (VIF), well below 10, allowed the assumption of no multicollinearity in the data.The Durbin–Watson statistic was used to test the assumption of being independent. The value of this statistic was 1.30 (perceived annoyance), 1.52 (perceived loudness) and 1.39 (perceived pitch), allowing the assumption of the residuals being independent.Homoscedasticity was assumed by observing a random distribution of values in scatterplots between the regression-standardised predicted values and the regression-standardised residual values.Exploration of the P–P plots, with data points close to the observed vs. expected cumulative probability diagonal line, allowed the assumption of residuals being normally distributed.Values of Cook’s distance below 1  allowed the assumption of no influential cases biasing the MLR models presented.An MLR analysis was undertaken to define the main contributors to perceived annoyance, perceived loudness and perceived pitch. All assumptions of MLR were checked before implementing the analysis:As shown in A multilevel analysis was also carried out to investigate whether the main contributors to perceived annoyance, loudness and pitch (as reported in 2) when removing it from the analysis. Following a ‘one-off’ approach previously implemented by Boucher et al.  and ToriThe results presented in this paper, in terms of correlation between metrics and drone noise perception, are consistent with existing literature. In line with Hui et al. , the subIn Christian and Cabell , the annDue to the COVID-19 pandemic, only the subjective experiment was carried out, and not as it is usually done under controlled laboratory conditions. As recently reported by the technical committee of the Acoustical Society of America on Psychological and Physiological Acoustics, online experiments can provide access to larger sample sizes and ecologically valid responses, but at the cost of compromising the calibration process and finding inconsistencies in participant experiences . AlthougAeq,4s  A careful process to calibrate the drone sounds to the target Lshown in  was carr(ii) The participants were instructed to complete the test with adequate headphones and in a quiet environment. However, it can be assumed that the quality and frequency response of the headphones used and the background sound level where they completed the test varied between participants.(iii) The online experiment was designed for the participants to reproduce the stimuli via headphones. There is uncertainty as to whether the headphones used by the participants were able to recreate the low frequency noise produced by the drones evaluated.Therefore, the research findings presented and described in this paper will be validated in a subsequent experiment carried out under controlled laboratory conditions and reproducing the test sounds via a loudspeaker array.This paper presents the results of a subjective experiment to investigate the noise perception of a comprehensive set of drone sounds encompassing different flying operations, size, weight and distance from the receiver. Based on a detailed statistical analysis, the responses of the participants for each drone sound were very consistent (even though the experiment was conducted online).For the drone sounds tested, the participants’ responses of perceived annoyance were mainly driven by PNL and sharpness, confirming the significance of the high-frequency content present in drone noise. For perceived loudness, participants’ responses were mainly driven by PNL and fluctuation strength. In this case, the beating effect due to rotor interactions might affect the perception of loudness. Perceived pitch was found to be highly influenced by sharpness, Aures tonality and roughness. In this case, the perception of pitch seemed to be driven by the high-frequency and tonal content along with the rapid amplitude modulation due to the unsteadiness of the sound signal.A robust logarithmic relationship was found between the perceived responses and distance from the receiver (quantified in terms of HAGL). An increase in HAGL of drone flyovers led to consistent reductions in perceived annoyance, perceived loudness and, to a lesser degree, perceived pitch. However, it was found that the perceived loudness declines more rapidly than perceived annoyance when HAGL increases. This means that increasing the distance of drone operations from communities is likely to lead to more substantial reductions in perceived loudness than perceived annoyance. This is likely due to other psychoacoustic factors, or even non-acoustic factors, on the perception of annoyance.The findings of this research could facilitate better understanding of the key psychoacoustic factors to account for in order to mitigate community noise impact when planning drone operations. The metrics proposed in this paper could also aid the effective assessment of human response to drone noise.Further research is needed to better understand the effects of drone noise on existing soundscapes, how ambient noise may mask drone noise, and the influence of this masking on the perception of drone operations.


There is a belief that tissue flossing can improve the range of motion or performance, speed up recovery, and decrease the pain caused by various diseases or injuries. As a result, many therapists, patients, and athletes are now using this technique. Consequently, in the last 5 years, a number of studies have addressed these assumptions. The purpose of this scoping review is to introduce the application of a floss band and to summarize the existing evidence for the effect of floss band treatment on the range of motion, performance, recovery, and pain (due to disease or injuries). A further goal is to suggest what needs to be addressed in future studies. The online search was performed in PubMed, Scopus, and Web of Science databases. Any studies dealing with the effects of a floss band treatment on the range of motion, performance, recovery, or pain parameters in any population  were included in this review. Twenty-four studies met the inclusion criteria, with a total of 513 participants. The included studies revealed that there is evidence that a single floss band treatment is able to increase the range of motion of the related joint and can positively affect jumping and strength performance. However, these findings show only small to moderate effect sizes. Although not yet clearly understood, a possible mechanism for such changes in the range of motion or performance is likely due to changed neuromuscular function, rather than changed mechanical properties, of the muscle . All in all, there is a need to conduct long-term studies about the effects of flossing treatment on the range of motion and performance  and its related mechanism . There is weak evidence that flossing can be of value for pain relief in the treatment of certain diseases and for speeding up recovery after exercise. Moreover, there is weak evidence that flossing might have a superior conditioning (warm-up) effect compared to stretching when the goal is to improve the range of motion or certain aspects of muscle strength, while no such superior effect has been reported when compared to foam rolling. Tissue flossing was first proposed by Starrett and Cordoza , who sugIn general, there is a belief that flossing can stimulate the mechanoreceptors in the underlying fascial layers, leading to reperfusion of the compressed tissue (hence leading to enhanced blood flow), or causes fascial shearing, and consequently the fascia's sliding potential will be restored , pain (caused by various diseases or injuries), injury, and disease, and also on recovery  in any kind of participant . A further goal is to compare a floss band treatment with other treatments  and to clarify if different pressure levels for the applied floss band have an impact on various outcomes.* OR performance OR rom OR recovery OR pain NOT dental NOT animal.” Since flossing is a relatively new technique, the search was restricted to the period from the year 2000 to November 23, 2020 . The inclusion criteria for this scoping review were any studies dealing with the effects of a floss band treatment on the range of motion, performance, recovery, or pain parameters in any population  in English and German language. This process resulted in a total number of 4,128 studies being identified. After removing the duplicates , the remaining studies were screened independently by two researchers (AK and RM) by title (or if necessary by abstract) to identify the studies to be included in this review. Following this blind screening process, the researchers compared their findings and discussed possible mismatches. Overall, 2,893 studies were screened, but only 14 met the inclusion criteria and hence were included in this review. Moreover, through an additional search of the references and the citations (Scopus and Google Scholar) of the 14 papers already included, 10 more studies were identified and included. Therefore, in total, 24 papers were included in this scoping review. A detailed illustration of the search process is provided in This review is based on the suggestions made by Munn et al.  with regThe mean percentage changes (pre- to post-) and the 95% confidence intervals (CIs) of the range of motion and performance parameters are presented in the subsequent chapters. In addition, according to previous suggestions Hopkins, , we defiIn total, 15 studies investigated the acute effects of a single floss band application on the range of motion of several joints. Eight studies applied the floss band on soft tissue , and the other studies applied the floss band on the joints, namely, on the ankle (five studies) or on the upper body (two shoulder/one elbow). For these 15 studies, 29 range of motion measures were extracted since some studies analyzed various functions of the joint   following the floss band application see . In mostMoreover, 12 further measures showed no significant change in the range of motion following a floss band application see . In addiTaking the significant and non-significant findings together, out of the 29 measures, in 27 measures, the percentage changes of the before-to-after comparison were reported. Concerning ankle flossing, 11 measures from five studies were extracted. Out of these 11 measures, seven were significantly increased. By considering just the main measure of each study on ankle flossing  following both ankle and calf flossing , indicating a small to moderate magnitude of change Cohen, . Thus, cOnly a handful of the selected studies investigated possible mechanisms behind such increases in the range of motion following a floss band treatment. With regard to a single stretching exercise, a possible mechanism for the changes in the range of motion is changes in soft tissue  and due to the fact that the sample sizes have been rather small, no general conclusion should be made.Since studies of the long-term effects of flossing have been diverse in terms of the population  and the treated joints  induced similar changes in the range of motion in some , and the other studies applied the floss band on the ankle joint (three studies), knee joint (one study), and shoulder joint (one study). Out of these 11 studies, 44 performance measures were extracted. Twenty-six measures were strength, torque, or power measures or rate of force development (RFD) measurements on an isokinetic dynamometer. Moreover, 10 measures were related to countermovement performance , seven measures were related to sprint performance , and one measure was related to balance performance  following the floss band application see  CMJ for CMJ for  may increase jump height, while sprint performance seems to be unaffected following ankle flossing. Moreover, thigh flossing seems to be a proper tool to increase the MVC of both the knee extensors and the knee flexors.According to the included studies about the acute effects of a floss band treatment, an increase in performance might indeed be possible. However, as in the findings for range of motion, these outcomes are not supported by high effect sizes. The effect size reported by the studies is, on average, 0.244 (ranging from 0 to 0.77), indicating a small to moderate magnitude of change Cohen, .A suggested mechanism by Driller et al.  underpinP = 0.06) following the 14 day intervention period. Although no further information about the exact wrapping technique or pressure was reported, the findings of Bohlen et al.  may increase jump height, and thigh flossing might have a positive impact on knee extensor and knee flexor MVC. However, the reported effect sizes are rather small . The possible mechanisms for such an increase in performance are increased muscle activity and improved neuromuscular function  and the control group . Thus, the authors concluded that a flossing treatment cannot induce a faster recovery rate or reduce DOMS. A possible difference between these two reports might be found in the floss band application. In the study of Prill et al.  in that the higher-pressure garments showed poorer recovery than the lower-pressure garments. Thus, it can be speculated that both floss bands and compression garments should be applied with lower pressure (<150 mmHg for floss band treatments and <15 mmHg for compression garments) to ensure a better outcome. However, more research is needed to investigate the effects of various pressures of the floss band application on different output parameters .Moreover, compression garments are used by athletes in the belief that they can speed up recovery. Unlike flossing, compression garments can be worn for several hours since the pressure is ~10-fold lower than that in a typical floss band application. A meta-analysis of compression garments , which is an accepted method in foam rolling  effect in a few parameters  were discussed. In general, there is evidence that a floss band treatment applied either on the joint or the soft tissue is able to increase the range of motion of the related joint. Moreover, joint flossing may additionally increase jump height, and flossing applied on the thigh can positively affect isometric strength. However, these findings showed only small to moderate magnitudes of change in the included studies. Although not yet clearly understood, a possible mechanism for such changes in the range of motion is likely due to increased stretch tolerance rather than changes in the mechanical parameters of the muscle . All in all, there is a need to conduct long-term studies about the effects of flossing treatments on various parameters like the range of motion or performance and their mechanism . Moreover, some case studies and studies with small sample sizes reported a reduction in pain (caused by various diseases or injuries) following a flossing treatment. However, more evidence and controlled studies are necessary to understand the effects of a flossing treatment or intervention  on pain and injury. Only two studies reported conflicting results about flossing and its effect on recovery. In terms of the pressure of the applied floss band, it can be recommended to apply less pressure (<150 mmHg), rather than more, to avoid a possible adverse effect or even a harmful effect. There is weak evidence that flossing might have a superior conditioning (warm-up) effect in some parameters, compared to stretching, when the goal is to enhance the range of motion or strength parameters. However, no such superior effect was reported when compared to foam rolling or instrument-assisted soft tissue mobilization.Since to date a lot of theories and only poor evidence exists on the topic of flossing, we strongly encourage performing further prospective studies about the acute and long-term impact on the healthy and impaired musculoskeletal system and the underlying mechanisms.AK and RM collaborated in the literature review and in producing the figures and tables. AK, RM, and MN collaborated in writing the manuscript. All the authors contributed to the article and approved the submitted version.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.