Dr Catherine Ha
email: c.ha@invs.sante.fr

Yves Roquelaure

Annette Leclerc

Annie Touranchet

Marcel Goldberg

Ellen Imbernon

The French Musculoskeletal Disorders Surveillance Program: Pays de la Loire Network

Keywords: Musculoskeletal disorders, Occupational Diseases, Occupational exposure, Epidemiology, Surveillance

Objectives: A pilot epidemiological surveillance system for work-related musculoskeletal disorders (MSDs) was implemented in 2002 in France's Pays de la Loire region by the French Institute for Public Health Surveillance, mainly to assess the incidence and prevalence rates of MSDs in the general and working populations, to identify the levels of exposure to physical and psychosocial work factors and to investigate the proportion of cases attributable to work exposure. Methods: The surveillance program combines three main components. The first is the epidemiological surveillance of sentinel health events in the general population. Carpal tunnel syndrome (CTS) was chosen as sentinel event for upper limb MSDs. Incident cases of CTS occurring in patients aged 20 to 59 were included prospectively from 2002 to 2004. The second part of the program, based on a network of occupational physicians (OPs), assesses the prevalence of the main upper-limb MSDs and their risk factors in the workplace. The third approach is based on the registration of notification of work-related diseases related to MSDs, with the cooperation of a network of OPs. Results: In the first part of the program, 1,168 incident cases of CTS were included during the 3 year-period. The estimated incidence of CTS was 1.00 per 1,000 person-years aged 20-59 (0.60 in men and 1.40 in women). The mean incidence rate was higher in employed than unemployed persons in the year of diagnosis (0.6 per 1,000 vs. 0.3 in men and 1.7 vs. 0.8 in women). Through the OP network, prevalence rates of clinically-diagnosed MSDs were high for both genders: about 13% of workers (11% of men and 15% of women) suffered from at least one of the six main upper limb MSDs. The most frequent disorders were rotator cuff syndrome, CTS and lateral epicondylitis. The survey on WRD showed that MSDs represented 65% of the notified work-related diseases.

Musculoskeletal disorders (MSDs) are impairments of bodily structures (such as muscles, tendons, nerves, vessels, cartilages) of the limbs and the back e.g. tendinitis and tenosynovitis (mainly shoulder tendinitis, lateral epicondylitis and hand-wrist tendinitis), peripheral nerve entrapment (mainly carpal tunnel syndrome and ulnar tunnel syndrome), bursitis, low-back pain and sciatica, and neuro-vascular syndromes (such as vibration white finger). Numerous non-specific peri-articular pain disorders have also been included under this umbrella term. [START_REF] Kilbom | Musculoskeletal Disorders: Work-related Risk Factors and Prevention[END_REF] Work-related musculoskeletal disorders are a leading cause of morbidity and work disability in the European Union 2,3 and represent one of the most disquieting issues in occupational health today. They cause considerable human, social and occupational burdens in terms of pain and distress in work and daily life, and may lead to irreversible functional after-effects, reduction of work capacity and risk of damage to a career. They have steadily increased in the last 15 years and represent the main cause of compensated occupational diseases in most of the industrialized countries. In France, more than 25,000 cases were awarded compensation for limb MSDs by the general National Health Insurance Fund (organisation that covers workers' compensation claims for more than 80% of the French population) in 2004, and more than 2,700 for chronic lower back disorders, representing 81% of all compensated diseases. [START_REF]Statistiques nationales des accidents du travail, des accidents de trajet et des maladies professionnelles[END_REF] These disorders entailed the loss of about 6.3 million days' work. [START_REF]Statistiques nationales des accidents du travail, des accidents de trajet et des maladies professionnelles[END_REF] MSDs are the first cause of disability before age 45 years and rank first among the causes of limitation in work for health reasons. [START_REF] Ferrand | Travail et Santé. Quelques résultats portant sur une population active, issus de l'enquête HID[END_REF] Moreover, they represent an economic challenge because of their consequences for the operation of companies, and their constant increase reduces competitiveness. Upper-extremity MSDs and low-back pain will be increasing problems in the years to come because of the predictable combined effects of ageing of the working population and the intensification of work.

Supprimé : then

The only source of information available in France to describe the current epidemic of MSDs is workers' compensation (WC) claims. However, this is known to be subject to considerable bias and to lead to underestimation of the extent of the phenomenon. [START_REF] Davis | Surveillance of work-related carpal tunnel syndrome in Massachusetts, 1992-1997: a report from the Massachusetts Sentinel Event Notification System for Occupational Risks (SENSOR)[END_REF][START_REF] Shannon | How many injured workers do not file claims for workers' compensation benefits?[END_REF][START_REF] Roquelaure | Active epidemiological surveillance of work-related musculoskeletal disorders (WMSDs) in a shoe factory[END_REF][START_REF] Goldberg | Regional differences in the compensation of pleural mesothelioma as occupational disease in France (1986-1993)[END_REF] As emphasized, accurate surveillance data on MSDs are needed to provide a basis for monitoring changes to target industries for additional prevention and regulatory actions over time. [START_REF] Gerr | Surveillance of work-related musculoskeletal disorders[END_REF] The Occupational Health Department of the French Institute for Public Health Surveillance (DST-InVS) therefore implemented a pilot epidemiological surveillance of MSD program in the Pays de la Loire region in 2002.

The aims of this program are: (i) to estimate the incidence and prevalence rates of the main MSDs in the general population of a French region and their time trends according to age, gender, economic sector and occupation; (ii) to assess the levels of the main occupational exposures; (iii) to determine the contribution of work-related physical and psychosocial risk factors to their development; (iv) to estimate the extent of under-declaration of work-related diseases (WRD) as compensatable occupational diseases; and (v) to assess the feasibility of such a system of surveillance before its extension to other regions in France. The program relies on 3 main components which were designed to provide a comprehensive view of the situation of the MSD epidemic in relation to work. The aim of this paper is to present the general design of the program and to illustrate the type of information that each of its components can provide. Supprimé : a Supprimé : ¶ METHODS This program combines 3 main components: (i) epidemiological surveillance of sentinel health events in the general population; carpal tunnel syndrome, the most commonly reported nerve entrapment syndrome, was chosen as the sentinel event for upper limb MSDs and sciatica with herniated disk as the sentinel event for back pain; (ii) epidemiological surveillance of the main upper-limb MSDs and their risk factors in the workplace; and (iii) registration of notification data on compensation claims for work-related diseases related to MSDs. The program was set up in the Pays de la Loire region (Loire Valley area, West Central France, 3,305,000 inhabitants and 1,247,839 wage-earning workers in 2002). This region represents 5.5% of the French population and 5.6% of the French working population. Its socioeconomic structure is diversified and close to that of the whole of France. 11 Epidemiological surveillance of sentinel health events in the general population Carpal tunnel syndrome (CTS) results from a compression of the median nerve at the wrist. It constitutes a major proportion of all registered and/or compensated work-related diseases in many countries. In France, nearly 40% of workers' compensation claims for limb MSDs in 2004 were for CTS, a higher proportion than for shoulder and elbow disorders. CTS occupational risk factors are well-established: highly repetitive work, force, combination of repetitive movements and force, extreme wrist postures and vibration. The purpose of this epidemiological approach was to assess the incidence of CTS according to age, gender, economic sector and occupation. This system of epidemiological surveillance of CTS was tested in the general population of Maine & Loire (one of the five "Departements" of the Pays de la Loire Region; 1.2% of the French population), aged 20-59 [193,802 men (49.9%) and 194,276 women (50.1%)]. 11 The methods were recently reported in detail. [START_REF] Roquelaure | Mis en forme : Anglais (Royaume-Uni) Supprimé : Disparités ré gionales de la reconnaissance du mésothéliome de la plèvre comme mal adie professionnelle en France (1986-1993)[END_REF] [START_REF] Katz | The carpal tunnel syndrome: diagnostic utility of the history and physical examination findings[END_REF] : numbness, tingling, burning, or pain in at least 2 of digits 1, 2 or 3; palm pain; wrist pain, or pain radiation proximal to the wrist were also included as symptoms for a probable CTS. Case definition agreed with consensus definitions for epidemiological surveillance of CTS and took into account the 2002 AAEM recommendations for the neurophysiological study of CTS. 13,[START_REF] Rempel | Consensus criteria for the classification of carpal tunnel syndrome in epidemiological studies[END_REF] Demographic, clinical and neurophysiological information was provided by the physicians. A questionnaire was then mailed to each patient. Information was collected on medical and surgical history (obesity, diabetes mellitus, thyroid disease, gynecological history, upper limb MSDs) and employment during the 5 past years (economic sector and occupation). The final response rate to the questionnaire was 97%. Incidence rates were estimated per patient (bilateral CTS counting as one case). The date of the electrophysiological examination was used as the date of diagnosis. Age-and genderspecific incidence rates were estimated by dividing the number of subjects suffering from CTS by the number of persons of the same age and gender in the general population according to the 1999 census. 11 The standardized incidence ratios (SIRs), as estimations of age-adjusted relative risks associated with an economic sector or an occupation, were calculated separately for each gender, using all economic sectors or occupations of the whole sample as reference. The age-adjusted relative risks (RR) of CTS according to industry sectors and occupation categories were computed using the Mantel-Haenszel method with the whole sample of subjects included in the study as reference, whether they were employed during the last 5 years or not. The attributable fractions of CTS among those employed in a certain economic sector or occupation category or subcategory (AFE [%]) were computed to estimate the proportion of CTS cases attributable to work in the economic sectors and occupations at high risk (when at least 5 cases of CTS occurred) using the following formula: AFE = (RR -1)/RR. [START_REF] Armitage | Statistical methods in medical research[END_REF] The methods and results from the surveillance of sciatica will be published in the near future.

Epidemiological surveillance of upper-extremity MSDs in the working population Occupational medicine is a medical speciality in France, and occupational physicians (OPs) receive four years specialist training. Their tasks include monitoring work exposure and performing annual health examinations, which are compulsory for all wage-earning workers. Most of the 7,000 currently practicing OPs work simultaneously across many companies and industries of the private sector which employs about 70% of France's 25 million labor force. The self-employed, civil servants, and public sector employees (such as Education sector employees) benefit from different occupational medicine arrangements. To provide data comparable with other European countries, our surveillance protocol used the recommendations of a Criteria Document for evaluating the work relatedness of upperextremity MSDs, published in 2001 by a group of experts (referred to as the Criteria Document in the remainder of the article). [START_REF] Sluiter | Criteria Document for evaluating the work-relatedness of upper extremity musculoskeletal disorders[END_REF] The aim of the surveillance system is to estimate prevalence rates of MSDs and their risk factors in the regional workforce according to age, gender, economic sector and occupation.

The methods were recently reported in detail. [START_REF] Roquelaure | Epidemiologic surveillance of upper-extremity musculoskeletal disorders in the working population[END_REF] Briefly, the design was based on a network of occupational physicians (OPs). All OPs who practised in this region were invited to participate, and 80 of them (17.4% of the region OPs) volunteered to take part in the study. Subjects were randomly selected from workers undergoing a regularly-scheduled annual health examination. The presence of non-specific musculoskeletal symptoms of the upper limbs during the preceding 12 months and the preceding 7 days was identified using the Nordic questionnaire. [START_REF] Hagberg | Work related musculoskeletal disorders (WMSDs): a reference book for prevention[END_REF] If symptoms had occurred during the last 12 months, a physical examination was performed by the physician using a standardized clinical procedure described in the Criteria Document for rotator cuff syndrome, lateral epicondylitis, ulnar tunnel syndrome, carpal tunnel syndrome, de Quervain's disease, and flexor-extensor peritendinitis or tenosynovitis of the forearm-wrist region. The final study population comprised 3,710 workers (2,162 men and 1,548 women), working primarily in manufacturing industries (33%), service industries (25%) or trade (13%), randomly included between April 2002 and April 2005. Women were slightly underrepresented in the sample (42% vs. 47% in the region). Overall, the distribution of economic sectors and occupations in the study sample was close to that of the regional workforce. Health status was assessed by a self-administered questionnaire and physical examination, and occupational risk factors were assessed by the same questionnaire. Exposure scores were computed for each anatomic area by combining the risk factors taken into account by the Criteria Document.

Work-related diseases

In France, compensation for an occupational disease is based on a limited number of "Tables". These Tables define the medical, technical and administrative conditions that are necessary and sufficient for the financial compensation of an occupational disease. Another category comprises "work-related diseases" (WRD) defined as diseases considered by the physician to be of occupational origin but not compensatable. The notification of putative WRD is an obligation for all physicians in order to update the Tables of occupational diseases. However, physicians seldom notify the diseases they believe to be linked to work conditions or occupational exposure. [START_REF] Verger | Barriers to physician reporting of workers' compensation cases in France[END_REF] Moreover, these notifications were not used for epidemiological surveillance due to the lack of information on the source population. The purpose of this part of the program was to estimate the prevalence of WRD in the working population according to age, gender and economic sector, and to assess the extent of underdeclaration of WRD as a compensatable occupational disease. A pilot registration system based on one week surveys repeated over 3 periods of six months was implemented in 2003 in the Pays de Loire region with the co-operation of a network of OPs. All OPs who practised in this region were invited to participate. The OPs notified the WRD they observed during the compulsory annual workers' consultations for each one week survey. In order to estimate prevalence rates, we also collected data on age, gender and economic sector for all the workers seen by the same OPs during the same period. Nearly half of the region's OPs volunteered to take part in the pilot stage (about 30% of the region's OPs participated in each of the three week surveys). They were representative of the region's OPs in terms of economic sectors covered and were responsible for 339,485 workers in all in 2003 (about a quarter of all salaried workers in the region).

In all components of the program, economic sector and occupation were coded using the French Activities Nomenclature "Nomenclature des Activités Françaises" (NAF codes) and the "Profession et Catégorie Sociale", the French classification of occupations (PCS codes). [START_REF]Nomenclature des activités et des produits française NAF-CPF[END_REF][START_REF]Nomenclature des professions et catégories socioprofessionnelles (PCS)[END_REF] Ethical approval for the program was provided by the French National Commission for Information Processing & Civil Liberties.

RESULTS

Since the beginning of this program of epidemiological surveillance, several analyses have been performed both for surveillance purposes and to provide information for the public and for health authorities. We present here some results from each component of the program, Supprimé : 0 Supprimé : [START_REF] Kilbom | Musculoskeletal Disorders: Work-related Risk Factors and Prevention[END_REF] Supprimé : summarize including some already published, to illustrate its contribution to epidemiological surveillance and research. [START_REF]La surveillance épidémiologique des troubles musculo-squelettiques[END_REF][START_REF] Evanoff | Feasibility of a job-exposure matrix for exposure assessment in studies of work-related musculoskeletal disorders of the upper extremity. 18 th International symposium on Epidemiology in Occupational Health[END_REF][START_REF] Melchior | Why are manual workers at high risk of upper limb disorders? The role of physical work factors in a random sample of workers in France (the Pays de la Loire study)[END_REF][26][27]29 Incidence of CTS in Maine & Loire A total of 1,168 incident cases (349 men and 819 women) corresponding to 1,644 wrists affected by CTS were included during the 3-year period. A few eligible patients refused to participate. The number of refusals was estimated by the physicians to be less than 10%. The crude average 12-month incidence of CTS over the 3-year period was 1.00 per 1,000 person-years aged 20-59 (0.6 in men and 1.4 in women), increasing with age (p < 0.001) in both genders regardless of employment status. A total of 1,135 patients completed the postal questionnaire [320 men, mean age 43.3 (SD 9.5), and 815 women, mean age 44.9 (SD 9.4)]: most of them were working at the time of diagnosis (81% of men and 66% of women), and 92.1% (96.9% of men and 90.2% of women) had worked in the last 5 years. The unemployed persons comprised subjects who had never worked, mainly women and long-term unemployed persons. The crude mean incidence rate of CTS per 1,000 person-years was higher in employed persons than in those unemployed in the year of diagnosis [0.6 vs. 0.3 of men and 1.7 vs. 0.8 of women (both p < 0.001)]. SIRs varied between activity sectors (Table 1). Working in the quarrying industry (mainly sand, stone and clay in the Pays de la Loire region), manufacturing (basic metals; manufacture of metal products; motor vehicles; furniture; wood and wood products, food and beverages industries) and construction was associated with an excess of risk in men. Working in agriculture, manufacturing (manufacture of motor vehicles, electrical equipment, chemical industries, food and beverages industries), services (hotels and restaurants, health and social work) and retail trade was associated with an excess of risk in women. In terms of occupation categories (Table 2), the workers affected by CTS belonged mainly to lower grade white collar and blue collar categories: material handlers, unskilled industrial, craft and agricultural workers of both genders; skilled craft workers in male workers; the categories for female workers were mainly trade and commerce employees (cashiers, food sales employees, self-service store employees), personal services employees (restaurant or café waitresses, hairdressers, domestic cleaners, child care workers), government executives and service workers (nursing auxiliaries, school cleaners, hospital cleaners). The attributable fractions of CTS to work among exposed persons (AFE) in occupations at high risk showed that a substantial proportion of cases of CTS diagnosed in lower-grade white collar and blue collar workers were attributable to work: AFEs reached higher values in female blue collar workers (67%) and lower-grade services, sales, and clerical white collar workers (61%). The AFE in male blue collar workers was 76%. High AFE values were observed in agriculture (58% for women), in manufacturing industries (from 58 to 92% for men and from 42% to 93% for women), construction (66% for men), personal service activities (66% for women), trade and commerce (49% for women) and hotels and restaurants (44% for women). 29 Epidemiological surveillance of upper-extremity musculoskeletal disorders in the working population Supprimé : [START_REF] Roquelaure | Mis en forme : Anglais (Royaume-Uni) Supprimé : Disparités ré gionales de la reconnaissance du mésothéliome de la plèvre comme mal adie professionnelle en France (1986-1993)[END_REF] Among the 3,710 workers randomly included between April 2002 and April 2005, 52% of men and 57% of women had experienced upper-extremity non-specific musculoskeletal symptoms during the preceding 12 months, and 27% of men and 35% of women had experienced these symptoms during the preceding week. Prevalence rates of clinicallydiagnosed MSDs were high for both genders: 645 cases were diagnosed in 521 workers. A total of 11.2% (95% confidence interval 9.9-12.6) of men and 14.8% (95% CI 13.0-16.6) of women suffered from at least 1 of the 6 main upper-extremity MSDs. The most frequent disorder was rotator cuff syndrome [6.6% (95% CI 5.6-7.6) in men and 8.5% (95% CI 7.1-9.9) in women], followed by CTS [2.4% (95% CI 1.8-3.0) in men and 4.0% (95% CI 3.0-5.0) in women] and lateral epicondylitis [2.4% (95% CI 1.8-3.0) in men and 2.5% (95% CI 1.7-3.3) in women]. Prevalence rates of the three other MSDs were lower (< 1%, except 2.1% [1.4-2.8] in women for De Quervain's disease). Prevalence rates increased with age for both genders, even after adjustment on seniority (p < 0.001). After age 50, 18% of men and 22% of women suffered from at least one MSD and 4% of men and 4% of women from at least two MSDs.

Prevalence rates of MSDs varied between economic sectors (Table 3). In men, prevalence rates were highest in the automotive industries [NAF code: 34], manufactured metal products [28], public administration [75], electrical and optical equipment [30-33], machine and equipment industries [29], rubber and plastic product industries [25]. In women, the highest prevalence rates were found in agriculture, several manufacturing industries (rubber and plastic industries [25], paper industry [21], garment industry [18], machine and equipment industry [29], furniture and wood industries [36]), and also in public administration [75], post and telecommunications [64] and hotels and restaurants [55]. High numbers of workers were exposed to at least two risk factors for MSDs of the neck (43%), shoulder (44%), elbow (50%) and wrist (60%). Excluding the neck, only 10% of workers were free of exposure to any of the 17 biomechanical or psychosocial risk factors listed in the 'Criteria Document'; 25% were exposed to one risk factor, 66% to two or more risk factors (39 % were exposed to at least four and 9 % to seven or more). According to the 'Criteria Document', a high percentage of cases of MSDs could be classified as 'probably work-related' (85% in women and 89% in women age < 50, and 87% in men and 90% in men age < 50). Exposure varied according to economic sector and occupation. Exposure was particularly high in quarrying industries, several manufacturing industries, agriculture and construction. The most exposed occupations were unskilled craft and industrial workers, skilled craft and industrial workers, storekeepers and agricultural workers.

Work-related diseases

For 23,416 workers seen in compulsory medical consultations during the three weeks of the pilot study (October 2003, April and October 2004), 1,056 notifications of WRDs were recorded. Work-related musculoskeletal disorders represented 65.1% of these WRDs, followed by mental and behavioral or psychological disorders (24.0%), diseases of the skin (4.9%), hearing problems (2.5%) and diseases of the respiratory system (1.9%). The prevalence of WRD was 4.6% of total diseases or symptoms, and 2.9% of work-related MSDs.

According to the OPs, 61% of the work-related MSDs could have been claimed as a compensatable occupational disease according to the conditions defined in the Tables. Only 11% (46 cases) of these 417 cases claimed compensation for an occupational disease. The absence of claims of MSDs for a compensatable occupational disease was explained in 43% of cases by the employee's refusal to claim, and in the remainder by recently diagnosed disease and lack of information about rights on the part of the employee or the physician. The body regions mostly affected for men were the lower back (32%), shoulder (25%), elbow and hand/wrist region (19%), and for women the hand/wrist (34%), shoulder (32%), lower back (20%) and elbow (17%). The economic sectors with the highest prevalence rates of musculoskeletal disorders were identified for each gender separately. The highest prevalence rates for men occurred in mining and quarrying, agriculture, construction and several manufacturing industries (pulp and paper, food and drink industry, furniture, non-metallic mineral products, motor vehicles, rubber and plastic products, machines and electric equipment) and also in membership organizations.

The highest prevalence rates for women were observed in agriculture and in some of the same manufacturing industries as men (rubber and plastics, machines and electric equipment, pulp and paper, food and drink, furniture, automotive industries) and in others such as manufacturing of wood and wood products, clothing products, shoe and leather products.

DISCUSSION

The program described here is an epidemiological surveillance system intended to provide permanent information concerning the trends and course of the current MSD epidemic on a population scale.

The CTS surveillance results provided the first estimation of the frequency of this MSD in the general population of a French district. This district is characterized by the high development of manufacturing and meat and poultry industries and by certain types of specialized cultivation (vineyards, horticulture and arboriculture). The limitations of the study were discussed in detail elsewhere. [START_REF] Roquelaure | Mis en forme : Anglais (Royaume-Uni) Supprimé : Disparités ré gionales de la reconnaissance du mésothéliome de la plèvre comme mal adie professionnelle en France (1986-1993)[END_REF]29 The main limitation was the lack of exhaustiveness of the surveillance network of physicians, which led to an underestimation of the incidence of CTS.

The male/female ratio in the rate of CTS per 1,000 person-years was similar between employed (0.35) and unemployed persons (0.37). These results could indicate that nonoccupational factors favouring a higher incidence in women have a similar influence in both genders. Similarly, AFEs values were about in the same proportion for both genders in blue collar workers and in manufacturing industries, suggesting that occupation factors have similar influence for men and women. The results showed variations according to sectors and occupations, in agreement with the results of Rossignol et al. in Quebec. 28 Our study identified 14 sectors with an excess risk of CTS: agriculture, quarrying, construction, manufacturing (food and drink industry, wood and wood products, chemical industries, basic metals and metal products, motor vehicles, electrical or optical equipment and electronic components, furniture), retail trade, hotels and restaurants, health and social work. These sectors represent about 22% of male employment and about 44% of female employment in Maine & Loire. Since many tests have been performed, we are aware that some of the significant results might be due to random effects.

Surveillance of the main MSDs in the working population revealed high prevalence rates for clinically-diagnosed MSDs: (95% CI [10-13]) of men and 15% [13-17]) of women suffered from one of the six upper limb MSDs and about 4% from at least two disorders. A very few eligible workers refused to participate (they were estimated to be less than 5%). The high prevalence of clinically-diagnosed MSDs contrasted with the relatively low level of work compensation claims for upper limbs MSDs in the same region (in 2003, about 3.7 WCs for 1,000 workers). This confirms that in France, as in other countries, using WC claims as a source of information leads to underestimation of the frequency of MSDs. Contrary to French and regional WC claims figures, the most prevalent disorder was not CTS but rotator cuff syndrome. The high prevalence rate of this disorder is disquieting, because of its poor medical and social prognosis. Another finding that is of importance for the prevention of MSDs was the high prevalence rate after age 50. The accumulation of MSDs in older employees probably reduces their functional capacity and increases the risk of disability and dismissal. The data generated by the epidemiological surveillance program were also used for research work. The feasibility of a job-exposure matrix for exposure assessment in studies of workrelated musculoskeletal disorders of the upper extremities was explored. [START_REF] Evanoff | Feasibility of a job-exposure matrix for exposure assessment in studies of work-related musculoskeletal disorders of the upper extremity. 18 th International symposium on Epidemiology in Occupational Health[END_REF] The factors associated with excess risk of upper limb musculoskeletal disorders in manual workers Supprimé : (2005) compared with other workers were investigated, and the variables which best summarized biomechanical exposure associated with upper-extremity disorders were identified. [START_REF] Melchior | Why are manual workers at high risk of upper limb disorders? The role of physical work factors in a random sample of workers in France (the Pays de la Loire study)[END_REF]27 Improved registration of WRD was observed during the three weeks of the pilot study, yielding more 1,000 notifications instead of 845 and 536 for the whole of 2001 and 2002, respectively, for all the OPs of the region. If repeated regularly, these short periods of registration should provide valuable information on the frequency of work-related pathological disorders, as well as an estimate of the extent of undeclared compensatable occupational diseases.

Geographic extension

The implementation of this pilot program of epidemiological surveillance of MSDs over three years (2002-2004) in the Pays de la Loire region identified the strengths and limitations of several sources of data and of different methods of collection. Based on that experience, we are currently preparing its geographic extension within the framework of a national program whose main objectives remain those of the Pays de la Loire pilot study. The program is being extended through its progressive implementation in several other regions chosen to be representative of French economic activity. The surveillance methods have been simplified for this extension. For the surveillance of sentinel health events in the general population, the program will rely on the use of the data of the French national hospital database for surgical cases. For the surveillance of the working population, a simplified self-administered questionnaire will be completed by a sample of workers, and only the three most frequent MSDs of the upper limb (shoulder tendinitis, carpal tunnel syndrome, lateral epicondylitis) will be investigated through a standardized clinical examination by OPs. For WRD surveillance, week-long surveys will be performed regularly. The first region to which the program is currently being extended is Provence -Alpes -Côte d'Azur (southeastern France), this region was chosen because its structure of the sectors of economic activity is quite different from that the Pays de la Loire region (fewer manufacturing industries, more services sectors). The surveillance of WRD has already been implemented in 7 other regions, covering about 29% of the French population. Extension of the data collection to the rest of the country will precise and strengthen the results observed on only one region and increase the probability of decision-makers looking seriously at the inequities in this system. Different selection biases may be introduced by the variation of the participating rate of OPs according to the region and the period of registration. These potential selection biases will be explored when data are available.

The Pays de la Loire experimental program already plays a significant role in informing the authorities and the public on the state and course of the current epidemic of MSDs, although the data gathered have still to be fully exploited. We planned to repeat our surveillance periodically, the next step will be conducted in 2011-2012 to study time trends. To our knowledge, such a program is unique, and we intend to extend it to a routine national epidemiological MSDs surveillance program within a few years.

Main messages • This program, firstly implemented in the Pays de la Loire region, is being extended to other regions of France.

• The crude mean incidence rate of carpal tunnel syndrome (CTS) per 1,000 person-years was higher in employed persons than in those unemployed in the year of diagnosis (0.6 vs. 0.3 of men and 1.7 vs. 0.8 of women). The attributable fractions of CTS to work among exposed persons were higher in blue collar and lower-grade white collar workers.

• Prevalence rates of clinically-diagnosed upper-limb MSDs were high for both genders (11.2% of male workers and 14.8% of female workers).

• According to the occupational physicians, 61% of the work-related MSDs could have been claimed as a compensatable occupational disease, but only a small number of them claimed for compensation.

Policy implications

• The aims of the French Musculoskeletal Disorders (MSDs) Surveillance Program are to:

-Estimate incidence and prevalence rates of the main MSDs and their time trends according to age, gender, economic sector and occupation.

-Assess the levels of the main occupational exposures.

-Estimate the contribution of work-related physical and psychosocial risks to their development.

-Estimate the extent of under-declaration of work-related MSDs as compensatable occupational diseases.

-Contribute to research.

• The Pays de la Loire program has already played a significant role in informing the authorities and the public on the state of the current epidemic of MSDs in France.

5 .

 5 Employees and clerks Public ser vices employees (PCS 51→53) Administrative employees and clerks (PCS 54) Trade and commerce employees (PCS 55) Personal ser vices employees (PCS 56) 6. Skilled and unskilled workers (PCS 61→69) Sk illed workers (PCS 61→65) Skilled industrial workers (PCS 62) Skilled craft workers (PCS 63)

  (i) to estimat e the incidence and the prevalence rates of the main MSDs in France; (ii) to identify the distribution according to occupations and economic sectors; (iii) to estimate the proportion of cases of MSDs attributable to work. ¶The Pay s de la Loire will continue its regional sur veillance and will also ser ve as the reference center.As such, some improve ments in the epidemiological surve illance methods, such as the in vesti gation of other sources of data, will be developed and tested. The Pays de la Loire will apply the full protocol of the sur veillance pro gram, and provide reference data for the other regions. ¶

  Incident cases of CTS occurring in residents of Maine & Loire were included prospectively by the four EDX) centers of Maine & Loire from 2002 to 2004. All cases were defined by both clinical and electromyographical criteria and the diagnosis was established by physicians specialized in EDX techniques. The clinical criteria were the classic/probable symptoms according toKatz et al. (1990)

	electrodiagnostic (
	Supprimé : carpal tunnel
	syndrome
	Supprimé : ,
	Supprimé : and computer use
	Supprimé : ¶
	Mis en forme : Exposant

Table 1 Standardized

 1 Incidence Ratios (SIR) of CTS according to economic sector (number of observed incident cases ≥ 5)

	Supprimé : or in press
	Supprimé :
	Supprimé : 2
	Supprimé : 6
	Supprimé : 8
	Mis en forme : Anglais (Royaume-Uni)

Table 2

 2 Standardized Incidence Ratios (SIR) of CTS according to occupation (French classification PCS)

	(Number of observed incident cases ≥ 5)
	Women 1. Farmers (PCS 11→13) 2. Craftsmen, salesmen, employers (PCS 21→23) 3. Managers and professionals (PCS 31→38) 4. Teaching associate professionals, health and social work intermediate occupations, administrative intermediate occupations of public and private companies, technicians and associate professionals, supervisors (PCS 42→48) 5. Employees and clerks (PCS 52→56) Government executive officials and services workers (PCS 52) 141 Observed Expected SIR (95% CI) 19 21.8 0.9 [0.5-1.4] 10 24.2 0.4 [0.2-0.8] 23 38.5 0.6 [0.4-0.9] 64 115.0 0.6 [0.4-0.7] 384 252.1 1.5 [1.4-1.7] 90.3 1.6 [1.3-1.8] Government executive officials (PCS 5215) 10 3.4 2.9 [1.4-5.4] Nursing Auxiliaries (PCS 5221) 38 18.2 2.1 [1.5-2.9] School cleaners and related cleaners (PCS 5216) 26 13.3 2.0 [1.3-2.9] Hospital cleaners (PCS 5222) 32 18.2 1.8 [1.2-2.5] Trade and commerce employees (PCS 55) 61 23.0 2.7 [2.0-3.4] Shop cashiers (PCS 5519) 18 4.4 4.1 [2.4-6.5] Food sales employees (PCS 5512) 12 5.0 2.4 [1.2-4.2] Self-service store employees (PCS 5518) 11 4.6 2.4 [1.2-4.2] Personal services employees (PCS 56) 117 69.1 1.7 [1.4-2.0] Restaurant or café waitresses (PCS 5611) 16 5.2 3.1 [1.7-5.0] Hairdressers (PCS 5622) 6 2.0 3.0 [1.1-6.5] Child care workers (PCS 5631) 64 41.9 1.5 [1.2-2.0] 6. Skilled and unskilled workers (PCS 62→69) 234 102.6 2.3 [2.0-2.6] Material handlers and related equipment workers (PCS 65) 11 1.8 6.2 [3.1-11.1] Storekeeper (PCS 6515) 8 1.5 5.2 [2.2-10.2] Unskilled industrial workers (PCS 67) 129 43.3 3.0 [2.5-3.5] Agricultural and food industries (PCS 6754) 24 3.6 6.7 [4.3-10.0] Sorting. packagin g and dispatch (PCS 6793) 23 3.3 7.0 [4.4-10.5] Mechanical machinery assemblers (PCS 6723) 13 2.1 6.1 [3.3-10.5] Electrical and electronic equipment assemblers (PCS 6711) 14 4.6 3.1 [1.7-5.2] Clothing industry (PCS 6772) 12 5.2 2.3 [1.2-4.0] Shoe and leather work (PCS 6773) 19 11.0 1.7 [1.0-2.7] Unskilled craft workers (PCS 68) 23 12.6 1.8 [1.2-2.7] Cleaners (PCS 6891) 19 9.3 2.0 [1.2-3.2] Unskilled agricultural workers (PCS 69) 48 12.4 3.9 [2.9-5.1] Orchard and vineyard (PCS 6914) 17 2.5 6.9 [4.0-11.1] Breeding (PCS 6912) 7 1.3 5.2 [2.1-10.8]

Table 3

 3 Sex-specific prevalence rates of at least 1 clinically diagnosed upper limb MSD according to Prevalence rates of MSDs varied according to occupation (Table4). For men, the highest prevalence rates were observed for public service employees (e.g., policemen and members of the armed forces) [PCS code: 51-53], skilled and unskilled industrial workers [62, 67] and storekeepers[65]. For women, the highest prevalence rates were observed for agricultural workers [69], skilled craft workers [63], skilled and unskilled industrial workers [62, 67], personal services employees [56] (personal care employees), and public service employees [51-53].

	the economic sector of employment
	Economic sector (French classification NAF)	At least 1 MSD	N	Men n	%	N	Women n	%

Table 4

 4 Specific prevalence rates of at least 1 clinically diagnosed upper limb MSD according to occupation

	Occupations (French classification PCS) 3. Managers and professionals (PCS 31→38)	At least 1 MSD	N	Men n	%	N	Women n	%
	Administrative mana gers (PCS 32→35)
	Directors and chief executives (PCS 37)
	Production and operations department managers (PCS 38) 4. Associate professionals and technicians
	Teaching, public ser vices and health associate professionals (PCS 41→43, 45)
	Administrative and commercial associate professionals (PCS 46)
	Technicians (PCS 47)
	Superv isors (PCS 48)

  The French Musculoskeletal Disorders (MSDs) Surveillance Program was implemented in 2002 by the French Institute for Public Health Surveillance.

•

Mis en forme : Exposant Supprimé :[START_REF] Shannon | How many injured workers do not file claims for workers' compensation benefits?[END_REF]

ACKNOWLEDGEMENTS

We thank all participating workers, occupational physicians and neurophysiologists involved in the Sentinel Network. Natacha Fouquet and Clarisse Rouillon helped in preparing the manuscript.

Conclusion:

The Pays de la Loire program already plays a significant role in informing the authorities and the public on the state of the current epidemic of MSDs. To our knowledge, such a program is unique. It is planned to extend it to a routine national epidemiological surveillance program in a few years.


Louis Garczynski

Mathieu Giraud
email: mathieu@algomus.frmanu@algomus.fr

Emmanuel Leguy

Philippe Rigaux
email: philippe.rigaux@lecnam.net

Modeling and Editing Cross-Modal Synchronization on a Label Web Canvas

Keywords: music annotation, music representations, web, cross-modal synchronization, score, audio

We present how the open-source web framework Dezrann enables to hear, study, and annotate music by interacting with synchronized views such as image scores, rendered scores, videos, and representations of audio as waveforms or spectrograms. We encode as unit conversions the cross-modal synchronization between these music representations. Composing these conversions allows us to conveniently translate musical time, audio time, and graphical positions, as well to synchronize annotation labels across views. Usages of the Dezrann platform or of some of its components include corpus annotation for musicology or computer music research, music education, as well as collaborative score edition and correction in the CollabScore project.

Introduction

Analyzing music can be viewed as "casting light upon music" [START_REF] Bent | Analysis[END_REF]). Music analysis is well-established on scores in common music notation. Music analysis builds upon music annotation of some elements in the score (patterns, harmonies, similarities, form, ...). These elements can be annotated while considering the score as Nattiez' niveau neutre [START_REF] Nattiez | Fondements d'une sémiologie de la musique[END_REF], but also with an historical, comparative or aesthetic perspective [START_REF] Caplin | Musical Form, Forms & Formenlehre -Three Methodological Reflections[END_REF]. We discussed before that some music annotation can be modeled as putting annotation labels on the score at various positions, possibly with a duration, and sometimes drawing relations between these labels [START_REF] Giraud | Using Dezrann in musicology and MIR research[END_REF].

Music annotation also helps other music-related activities, such as teaching, performing or even composing music. The "music analyst" can thus be a researcher in music theory or in computer musicology, a teacher, a student, a performer, a composer, a music lover. They may engage with music itself through hearing or feeling, but also with scores (or with any other music representations) through reading, annotating, and analyzing. Can they use numeric tools to help or to foster these activities?

Web platforms for music annotation. There are many web platforms to render, and sometimes to annotate, scores in common Western music notation, both academic [START_REF] Hoos | The GUIDO music notation format[END_REF][START_REF] Couprie | iAnalyse : un logiciel d'aide à l'analyse musicale[END_REF][START_REF] Pugin | Verovio: A library for engraving MEI music notation into SVG[END_REF][START_REF] Carey | NetScore : An image server/client package for transmitting notated music to browser and virtual reality interfaces[END_REF][START_REF] Lepetit-Aimon | INS core expressions to compose symbolic scores[END_REF]Sapp 2017) and commercial (including flat.io, jellynote.com, notezilla.io). Some of these platforms are designed to analyze music and share music annotations or analyses. Within the Dezrann project [START_REF] Giraud | Using Dezrann in musicology and MIR research[END_REF], we aim at providing a cross-modal platform for easy music annotation and analysis for everyone, including for people with limited programming background but also for people needing to annotate large music corpora. Music is presented either on several views -as scores or waveforms/spectrograms. The user creates, updates and edits labels on any of these views.

Synchronizing sources. Any cross-modal platform for music annotation faces the problem of music representation and encoding, and especially the link between sources with different representations -including audio, symbolic, image, and annotations.

As far as possible, generic and portable standards should be used to model links between documents. The W3C Web Annotation Data Model 1 enables linking towards any resource. The IIIF Image API 3.0 specification 2 allows anchors to any region in an image.

On the image side, Optical Musical Recognition (OMR) is a very active field of research (see review in (Calvo-Zaragoza 2020)). Beyond OMR, some studies addressed image-score alignment. Transcribing music often needs expert and/or crowd correction or raw input (Burghart 2017; deGroot Maggetti 2020).

On the audio side, software like Sonic Visualiser 3 or Audacity 4 allows to tap markers -that can be beats, measures, or noteworthy points --and to further edit these markers, but without any notion of (symbolic) musical time. Full-featured Digital Audio Workstations (DAW) such as Ableton, Logic, or Ardour5 do model measure/beat information, and sometimes offer a visualization of a grid of the musical time. A typical DAW task is to move or sometimes stretch audio to fit such a pre-existing grid. On the other hand, for some applications such as score following, analysis or more generally research in digital humanities, the audio may be given, and one goal may be to synchronize that audio (without altering it) with a (symbolic) music representation. Synchronization between audio and musical time can be either as simple as two start/end points, a few points, a systematic annotation of beats and/or measures, or a combination of these --for example start/end points with a few more synchronization points at which the tempo is changing.

Audio-score alignment and score following are also very active fields of research [START_REF] Ewert | High resolution audio synchronization using chroma onset features[END_REF][START_REF] Dorfer | Learning to listen, read, and follow: Score following as a reinforcement learning game[END_REF][START_REF] Mueller | Cross-modal music retrieval and applications: An overview of key methodologies[END_REF][START_REF] Thickstun | Rethinking evaluation methodology for audio-to-score alignment[END_REF]). Common methods are dynamic time-warping algorithms, or, today, deep learning approaches. Possible strategies are to align two audio sources (one generated from the score), usually by their chromas, or to directly align chromas with the score. Libraries such as librosa6 implement some of these algorithms. The quality of these alignments is improving but may require expert correction. Repeats (and jumps) are also challenging to model and to detect [START_REF] Shan | Improved handling of repeats and jumps in audio-sheet image synchronization[END_REF]). Anyway, several recent studies released significant corpora with audio/image/videos aligned to scores or other symbolic music information [START_REF] Balke | Bridging the gap: Enriching YouTube videos with jazz music annotations[END_REF][START_REF] Kosta | Mazurkabl: score-aligned loudness, beat, expressive markings data for 2000 Chopin mazurka recordings[END_REF][START_REF] Weiß | Schubert Winterreise Dataset: A multimodal scenario for music analysis[END_REF].

Contents. We do not address here automatic synchronization issues but rather focus on how to conveniently model, edit, and use such synchronization information, either starting from scratch or correcting an automatic synchronization information. Hence the synchronizations could be "perfect", but will often be "approximate", and a platform has to do its best to "degrade gracefully" the available information: An approximate synchronization still enables many applications such as score following or annotations.

We present here a simple way to model cross-modal synchronizations, with interpolation, to link several music representations (Section 3). Within a complete refactor of earlier version using Vue.js, the new Dezrann framework enables the interaction with a label canvas, scores backends (Verovio/Lilypond), audio/video backends (HTML5, YouTube) through both a full annotation platform and an independant component to edit synchronization files between audio and symbolic representations of music (Section 3). We conclude by discussing current and future usages of these tools (Section 4). given by the rendering software, whereas dashed arrows show ConvUnits that could be inferred through (a) OMR or (b) score/audio alignment, but that could also be edited/corrected within a synchronization editor.

Synchronizing through Conversions between Units

We distinguish here symbolic scores (structured encoding such as MEI or other formats), rendered scores (graphical representation of the former, rendered by some rendering software), and image scores (scanned printed scores or autographs).

On computational music analysis applications, we would like that musical time (symbolic position in measure and beats, such as "measure 13, beat 3.5") plays the pivotal role, both to browse synchronized scores and to annotate some of their elements. Such a symbolic musical time is relevant for most (but not all) of the notated Western music. An annotation label may thus be given as "measure 13, beat 2 to beat 3", with additional staff and/or other data information. However, the musical time can not be easily extracted, neither from an image file representing a score, nor from an audio file.

But sources representing a different aspect of music, such as (symbolic representations of) scores, images, audio, or videos, can be aligned. We model the conversion between one unit of measurement to another one into an abstract object that we call ConvUnit. This enables both audio and image synchronization, allowing to refer to the musical time even when annotating or playing from other representations.

A ConvUnit is a sorted list of synchronization points targeting two sources. The ConvUnits encodes the following conversions (Figure 1):

• image/musical time (X(Y)-positions/onset, (a)): For rendered scores, this conversion may be provided by the rendering software. On scanned scores, it may be provided by OMR software and/or corrected or entered by human input. The current implementation of ConvUnits uses X-positions for score images, identifying positions in continuous single-staff music that may be horizontally scrollable.

• audio time/musical time (timestamp/onset, (b)): For rendered audio, this conversion is usually trivial: Even when there are tempo changes, the audio software can provide such data. For any other audio file, the conversion can be produced by audio/score alignment methods and/or corrected or entered by human input.

• image/audio time (X(Y)-positions/timestamp, (c)): Mapping the X-position of any linear representation of music --waveform, spectrogram --to the audio timestamp is most of the time a trivial linear conversion requiring only start/stop points. This is the only conversion needed for music applications that considers only an audio file. In this case the musical time is useless.

Focusing on conversions between units rather than on the units themselves ease flexible chains of conversions: Any value can be converted to any other, possibly using interpolations. As example, composing the (a) and (b) ConvUnits produce a combined X(Y)-positions/timestamp conversion for score following or other applications. We now use the ConvUnits shown in the Figure 1, but other ConvUnits could be added and the conversion could be generalized to any tree structure, or even to any graph structure provided preference rules for conversion paths.

A Canvas Framework for Synchronized Views

This section details how we implement features on a set of synchronized views through ConvUnits, with possibly annotation labels that can be moved/edited on different views.

Backends

Audio/Video backends. The audio sources are displayed either through the HTML5 `<audio>`tag, or through the `youtube-player`plugin. Both enable to get or to set the playback position that will then be converted through the ConvUnit audio time/musical time. Waveforms and spectrograms are generated with SoX 7 . Score backends. Two backends render scores along with the ConvUnit image/musical time.

As an example, we report sizes on the madrigal Di nettare amoroso by Di nettare amoroso ebro by Luca Marenzio (uncompressed MEI of 1.4 MB, 1600+ notes in 133 measures).

• Lilypond8 . Lilypond `.ly`files were first generated with music21, but the support of Lilypond is not optimal in music21 9 . They can also be generated through `MusicXML2ly`, after conversion into `XML`by music21. The ConvUnit list is obtained through patching the `.ly` file in order to output the position of every note and bar.

Synchronizing Views on a Behavior-based UI

The front interface is based on the Vue.js 2.6 framework 10 with Vuetify material design UI elements 11 .

Behaviors. Complex graphs tend to have ridiculously large code space. Because any single action such as a click can have dozens of different effects depending on where and when it happens. Instead of segmenting the codebase on events, we segment the codebase as a list of features, which can all be toggled depending on the context. The user interface (UI) is 11 https://vuetifyjs.com 10 https://vuejs.org 9 https://github.com/cuthbertLab/music21/issues/433 thus based on renderless behavior slots12 : Components expose behaviors that can be inherited, customized, or detailed.

Behaviors rarely are linked to a UI element, because they live and die in the canvas. A behavior is rather a link between an event (a click, another behavior finishing its job, etc.), and an action (deleting a label, moving a label, etc.). Some behaviors further display an element in the canvas, such as the music cursor. In that case, the event is "audio player updating its timestamp", and the action is "update the cursor in the canvas". Developing with such behaviors improves code reusability and portability. One defines several (possibly inherited) behaviors enabled in different situations, such as desktop/mobile usage, simple/advanced modes, or active/inactive depending on the availability of audio or the current selection. This is very close to how humans think about a codebase, a list of features to be implemented, and sometimes removed. Views. Each source is represented on a view, possibly with labels. The playback cursor is always synchronized between views with the ConvUnits. The synchronizations can be further used in two ways:

• The common usage of such an application is to keep all the views synchronized.

Scrolling any representation of the music, playing the music, or creating or modifying a label on any view updates the other views and their labels, using the ConvUnits. This enables both playback applications while browsing various sources (rendered score, autograph, ...) as well as analysis applications (Figure 2).

• Conversely, to edit the synchronization, one typically needs to update the synchronization data on one source while freezing it on the other. We propose a synchronization editor that displays the ConvUnit list. The editor is currently implemented for the audio/musical time synchronization (Figure 3). In the edit mode, any synchronization point can be added or updated, either on the representation of audio or on the score. In the tap mode, one can tap points at regular intervals such as measures. The modes can be mixed: The user can thus synchronize a score starting with two start/stop points, adding manually a few points when the tempo changes, tap a few sections where the synchronization is more elaborated, and finally correct some of these points as needed.

The components offer import and export features for analysis labels but also for the synchronization itself. 1587), editing the synchronization against the spectrogram of an audio file. The colors help to identify the corresponding synchronization points. Regular points (such as here on bars with syncopations) are added in the tap mode. The synchronization is refined with the edit mode, for example on slow-down before cadences -the user is here updating the point on the last eighth note before the end of a phrase (Rat-to fui).

Applications and Discussion

The Dezrann platform and the prototype synchronization editor are available at www.algomus.fr/dezrann, and the code is released under the GPLv3+ license. We discuss here the usages of these software, focusing on the added value of synchronization between different sources.

The Dezrann platform is used for annotation of corpora for research in musicology and computational musical analysis -whether in support of manual annotation, in visualization of automatic or semi-automatic analysis results and in the evaluation of these results. The platform was used in the encoding of corpora including patterns, rhythms, harmonies, texture and form: Such corpora distributed total to more than 3000 labels and are openly distributed on www.algomus.fr/data and through Dezrann. Some music analysts work only on scores, and may not benefit from other synchronized sources. Conversely, the presentations of other sources and the ability to edit the synchronizations is interesting for music historians or researchers on interpretations. Research (and practice!) of Folk music is also mostly based on field recordings that also benefit from synchronization capabilities.

Music pedagogy seeks the engagement of children in active listening [START_REF] Vitale | The Importance of active listening and reflection in the music classroom The Canadian Music Educator[END_REF]. Dezrann is also thus intended for education in music and computer music, whether in specialized courses in music schools (such as harmony or analysis) or in music education in primary or secondary schools. Non-sight-readers, or people learning or improving their skills in music (sight-)reading, benefit from switching between scores and audio/video files -but the synchronization should be prepared by the teachers.

In 2021/2022, a pilot program gathers classrooms in five secondary schools (ages 10-16) [START_REF] Sauda | Soutenir en classe l'écoute active, l'autonomie et l'échange en analyse musicale avec la plateforme web Dezrann[END_REF]. Each classroom hosts between four and six 1-hour sessions on the platform, partly helped by a mediator conveying music (and computer music!) discourse to the children. Most of these children do not have any specialized music education -and do not read scores at all. For them, the audio (or the video) is the most informative source, or even the only one. In the first session, the mediator introduces a piece, chosen by the teacher from a catalog of a few pieces, and uses the platform to hear and annotate music elements. Note that the focus is not on the platform -but rather on actual music concepts on which the children are working, the platform being as "transparent" as possible. In the following sessions, the teacher freely selects any piece. The mediator or the teacher led these sessions, aiming at improving both children's autonomy while listening to musicalone or in groups of two or three -and also to share and discuss their work.

We attended seven of these sessions, observing both children and teacher usage. Children manage both to be autonomous in their analysis and are eager to report and share their analysis with others, thus improving their engagement [START_REF] Sauda | Soutenir en classe l'écoute active, l'autonomie et l'échange en analyse musicale avec la plateforme web Dezrann[END_REF]. During the sessions, children themselves proposed new usages, including the possibility that each of them chooses a piece to analyze and presents it to the classroom with their analysis, thus improving their engagement again. We also organized two feedback meetings with teachers. Following these reports, ergonomy was improved, bugs were corrected, and functionalities were added or scheduled.

Finally, through the synchronization component, the platform allows future usage in collaborative score correction. The CollabScore project will use some of the techniques presented here to build a cross-modal demonstrator: Given a symbolic score obtained from a (possibly faulty) OMR process, synchronize both the obtained encoding (MEI) and the original image to allow for crowd-sourced corrections.

Modeling and displaying synchronizations between representations of music -as well as being able to update these cross-modal synchronizations -help thus research, education, and practice of music. Perspectives include extending the synchronization components for audio/video, allowing to flexibly edit the synchronization on score imageswith also bounding boxes based on (possibly partial or faulty) OMR results. For this, future implementations of ConvUnits will target both rational numbers and also non-numeric values to better model repeats, and extend the handling of Y-positions for bounding boxes.

Figure 1 .

 1 Figure 1. ConvUnits describe synchronizations between (a) image/musical time, (b) audio time/musical time, and (c) image/audio time. Plain arrows show ConvUnits that are either trivial (2 synchronization points) and/or given by the rendering software, whereas dashed arrows show ConvUnits that could be inferred through (a) OMR or (b) score/audio alignment, but that could also be edited/corrected within a synchronization editor.

Figure 2 .

 2 Figure 2. Autograph of the fugue in C Minor BWV 847 by J.-S. Bach (D-B Mus.ms. Bach P 202) synchronized with a performance by Kimiko Ishizaka (bottom, http://welltemperedclavier.org) as well as fugue annotation labels from (Giraud 2015).

Figure 3 .

 3 Figure 3. Rendering with Verovio the madrigal Di nettare amoroso ebro by Luca Marenzio (1587), editing the synchronization against the spectrogram of an audio file. The colors help to identify the corresponding synchronization points. Regular points (such as here on bars with syncopations) are added in the tap mode. The synchronization is refined with the edit mode, for example on slow-down before cadences -the user is here updating the point on the last eighth note before the end of a phrase (Rat-to fui).

https://ardour.org 4 https://www.audacityteam.org 3 https://www.sonicvisualiser.org 2 https://iiif.io/api/image/3.0/#41-region 1 https://www.w3.org/TR/annotation-model

https://librosa.org

https://www.lilypond.org 7 http://sox.sourceforge.net

https://www.digitalocean.com/community/tutorials/vuejs-renderless-behavior-slots

Acknowledgements

We thank all users of the Dezrann platform for their usage and their feedback. We thank the Sciences Infusent program of the Université de Lille for their support in the pilot program with music education classrooms. We also wish to thank the Mésocentre de Lille for their computing resources and the hosting of the platform, and we gratefully acknowledge support from the ANR CollabScore ANR-20-CE27-0014 project and by the CPER MAuVE (ERDF, Hauts-de-France).


Sébastien Rouquette

Camille Cambon

Issam Bendaoud

Fabien Soulié

Residual stresses in ss316l specimens after deposition of melted filler wire

Keywords: WAAM, GMAW, Neutron Diffraction, Residual stresses

In this communication, two specimens are studied upon which a filler-wire is melted and deposited under electric arc heating. The process of interest is called wire and arc additive manufacturing. Such process produces mechanical parts with high tensile stresses and important geometrical distortions. The focuse is made on the residual stresses in the specimen. The effect of each deposited layer on the residual stresses is investigated with the neutron diffraction technique. The highest longitudinal stress values are measured under and at the parent -deposit surface where occurs the highest heating and cooling phases. The deposition of the 2 nd layer has reduced the tensile longitudinal stress values of 60 MPa. The thermal cycle due to the deposition of the 2 nd layer likely acted as a partial heat treatment of the previous melted and heat affected zones. A 2D stress map has been done from the one layer specimen lots of nuetron diffraction have been done. This 2D stress map shows that the inner part of the specimen is under compressive stress while the deposits are under tensile stress with a stress peak located near the parent -deposit interface. The longitudinal stress decreased from this peak till the top surface of the last deposit.

Introduction

Additive manufacturing (AM) techniques are based on layer-by-layer accumulation of molten material with the aid of CAD model in the aim to develop three dimensional parts [START_REF] Jin | Wire arc additive manufacturing of stainless steels: A review[END_REF]. Compared with traditional manufacturing, Additive Manufacturing (AM) have the ability to produce complex components with less waste of materials and energy [START_REF] Jin | Wire arc additive manufacturing of stainless steels: A review[END_REF][START_REF] Ding | A multi-bead overlapping model for robotic wire and arc additive manufacturing (WAAM)[END_REF][START_REF] Martina | Investigation of the benefits of plasma deposition for the additive layer manufacture of Ti-6Al-4V[END_REF]. Metal additive manufacturing processes utilize laser beam, electron beam, or electric arc as the heat source and the feedstock material can be in the form of powder, wire, or sheet [START_REF] Jin | Wire arc additive manufacturing of stainless steels: A review[END_REF]. The processes using electric arc energy are named wire arc additive manufacturing (WAAM). This technique has the potential to build up parts up to few meters with relatively low forming costs and high manufacturing efficiencies [START_REF] Li | A comparative study of wire feeding and powder feeding in direct diode laser deposition for rapid prototyping[END_REF]. In the WAAM process, the metallic wire is heated by the electric arc, then melted and transferred to the melt pool. As the welding torch moves on, the rear of the weld pool solidifies letting place to a deposit. Thus another layer is deposited on the top of the former. The AM part is built layer-by-layer.

However, few issues slow the wide spread of WAAM techniques such as : large surface roughness, anisotropy of the microstructure, high hardness, ... As the number of layers increases, the microstructure exhibits large columnar grains up to millimetre size crossing the layers. Furthermore, high tensile residual stresses and important distortions are present in WAAM parts [START_REF] Ding | Thermo-mechanical analysis of Wire and Arc Additive Layer Manufacturing process on large multi-layer parts[END_REF]. In welded structures, the tensile residual stresses reduce the fatigue strength and the toughness [START_REF] Colegrove | Welding process impact on residual stress and distortion[END_REF]. Residual stresses are mainly caused by the compressive yielding that occurs around the melted zone as the material heats and expands under arc heating. When the weld metal cools down, it shrinks which causes a tensile residual stresses, particularly in the longitudinal direction.

Two specimens are studied in this communication: the first one has one deposit and the second one has two overlaid deposits (or layers) on parent's edge. The parent material is in SS304L and the filler wire is in stainless steel 316L. A Cold Metal Transfer Gas Metal Arc Welding generator (CMT-GMAW) was used to melt the filler wire and, then, it is dropped off on the parent material. The experimental setup has been designed such as the AM parts are built under plane stress assumption.

As a consequence, the strain -stress analysis is reduced to two dimensions. Neutron diffraction (ND) strain measurement has been used to evaluate the residual stress field in the two specimens. ND is a non-destructive technique that provides insights into strain and stress fields deeper inside the engineering structures [START_REF] Allen | Neutron diffraction methods for the study of residual stress fields[END_REF]. The neutron diffraction measurement have been performed at the SALSA beam line, ILL, Grenoble, France [START_REF] Rouquette | Strain/stress measurement of 316l stainless steel additively manufactured walls with gas metal arc welding process[END_REF][START_REF] Rouquette | Residual stress state of additive manufactured 316l stainless steel parts: Round 2[END_REF]. The residual stress distribution inside the parent material and the deposits are presented and the influence of the deposition of 2 nd layer is discussed especially in the critical melted zone where the high stress gradient and textured microstructure are presents.

2 Description of the specimens

Operating conditions and specimen geometry

A schematic representation of the specimen with 1 layer is reported in figure 1 and a photography of the two layers specimen is presented in figure 2. The parent material is made of stainless steel 304L and the dimensions are 149 x 100/53 x 6 mm 3 . During the deposition procedure, the parent material is clamped on the left side (the largest). The other extremity is free to move. Up to 2 layers are deposited on the top surface of the parent as depicted in figure 1. The neutron strain scans were performed along 3 different sections for the 1 layer specimen in the aim to get a full 2D residual stress field while it has been done along one line for the second specimen. The process parameters: voltage, current, welding speed and shielding gas are reported in table 1. The first layer has been done with an higher energetic parameter in order to reduce the sink effect of the parent material. Then the second layer has been performed with a lower linear welding energy. The parents were cut off with plasma cutting machine from the same SS304L sheet.

Texture analysis

The texture analysis has been investigated by electron back scattered diffraction (EBSD) in order to determine if there was any preferred orientation in the microstructure of either the parent or deposits materials. The studied samples are displayed in figures 3 and 4 extracted at section V55 for both specimen (see figures 1 and 2. The two figures 3 and 4 exhibit large columnar grains in the direction of deposition (z direction as in figure 1). The length of the grains is of few millimetre for the 2 layers specimen. Unfortunately, the two EBSD figures are of poor quality because the polishing was extremely difficult on the 304L and 316L stainless steels. A small zone of equiaxed grains is visible in the centre of the first layer, see figure 3. The principal cristal direction is 001 as it is observed on the two EBDS figures (red colour). The growth of the grains is characteristic of the WAAM process leading to anisotropic material properties [START_REF] Pratihar | Neutron diffraction residual stress measurements in a 316L stainless steel bead-on-plate weld specimen[END_REF]. During the solidification, emergence and growth of dendrites are in the opposite direction to the heat flow. WAAM metallic parts often results in a columnar grain structure, leading to a highly textured material with anisotropic material properties [START_REF] Pratihar | Neutron diffraction residual stress measurements in a 316L stainless steel bead-on-plate weld specimen[END_REF].

Neutron strain measurements and residual stresses

Neutron diffraction measurements were carried out on SALSA beam line (Strain Analyser for Large and Small scale engineering Applications). SALSA is the dedicated engineering diffractometer Institute Max Von Laue Paul Langevin, Grenoble (France) [START_REF] Pirling | SALSA-A new instrument for strain imaging in engineering materials and components[END_REF].

A full diffraction pattern was measured at a fixed wavelength, λ = 1.66 Å and a 2θ = 98.502 • for Fe-311 cristal plane. Measurements were made along three directions; the longitudinal direction (LD) parallel to the layer, the transverse direction perpendicular to the layer (TD) and the normal direction (ND), perpendicular to the surface of the plate. The normal and longitudinal directions were measured without unmounting the specimen but it required a rotation of the platform. The sample had to be repositioned once to measure the third direction: the transverse one. Instrument gauge volume of 2 x 2 x 0.6 mm 3 was used for measurements in the three directions.

Theoritical background: from Bragg's law to the stresses

The measurement of residual strains by neutron diffraction is based on Bragg's law [START_REF] Hutchings | Introduction to the Characterization of Residual Stress by Neutron Diffraction[END_REF]:

λ = 2d hkl sin θ hkl ( 1
)
where λ is the wavelength of the neutron beam, d hkl is the lattice spacing of atomic planes characterised by Miller indices h k l and 2θ hkl is the scattering angle of the peak being measured. For monochromatic beam diffraction, the wavelength is fixed and its magnitude known and the measurement of 2θ hkl gives the lattice spacing. The strain in the same direction is then computed from the change in the interplanar spacing of the material according to the unstressed state as [START_REF] Krawitz | Use of position-dependent stress-free standards for diffraction stress measurements[END_REF][START_REF] Ohms | NET TG1: Residual stress assessment by neutron diffraction and finite element modeling on a single bead weld on a steel plate[END_REF] :

i = d i -d 0 hkl d 0 hkl = sinθ i sinθ 0 hkl -1 (2)
It is common use to define that the principal axes for linear welds are the longitudinal direction in the weld (LD), the transverse direction (TD) and the parent material normal direction (ND) [START_REF] Holden | Stress measurements in welds: Problem areas[END_REF]. As the parent material thickness is 6 mm and this dimensions is smaller according to the length and heigh, it is assumed that the normal stress will be close to zero. Moreover, it was supposed that LD, TD and ND were the principal directions. Then, the measurements of diffracted 2θ angles were performed in these three directions. Once the three principal strain components are measured, the stress in each direction is calculated using Hooke's law through the following equation:

σ ii = E 1 + ν ii + νE (1 + ν)(1 -2ν) 3 i=1 ii (3)
where E is the elastic modulus and ν is Poisson's ratio. Crystallographic moduli relevant to the considered single planes (i.e. Fe-311) are required for monochromatic instruments. The macroscopic and crystallographic values of E and ν used in this study were: E = 182 GPa, ν = 0.307. They were sourced from H.M. Ledbetter [START_REF] Ledbetter | Elastic properties of zinc: A compilation and a review[END_REF].

The reference θ 0 angle is determined according to the plane stress assumption [START_REF] Akrivos | Neutron diffraction measurements of weld residual stresses in three-pass slot weld (Alloy 600/82) and assessment of the measurement uncertainty[END_REF]. The reference θ 0 angle is required for the computation of the strains according equation 2. Thus, it imposes that the normal stress is null: σ norm = σ Y Y = 0. This condition can be written as follows:

σ Y Y = E 1 + ν Y Y + νE (1 + ν)(1 -2ν) ( XX + Y Y + ZZ ) (4)
It comes for Y Y Y Y = -ν 1 -ν ( XX + ZZ ) (5)
Secondly, the equation 2 can be simplified such as:

Y Y = θ Y -θ 0 θ 0 (6)
Finally, by introducing equation 6 into equation 5 and solving for getting θ 0 , it comes:

θ 0 1 -ν 1 + ν [θ Y + ν (1 -2ν) (θ X + θ Y + θ Z )] (7)
Once the longitudinal and transverse strains are calculated, the residuals stresses can be deduced by applying Hooke's law, equation 3. The longitudinal and transverse stresses are opresented in the next section without presenting the micro-strains.

Residual stress field in the one layer specimen

The specimen was scanned with neutrons along 3 different lines: 3 verticals as presented in figure 1. The three longitudinal stress distributions are reported in figure 5. The three longitudinal stress distributions are very similar in the parent material. The few differences are noticed close to and within the melted zone thus in the deposit for z > 45 mm. The longitudinal stresses in sections V25 and V85 are also very similar in the melted zone. The one calculated in section V55 shows higher longitudinal stresses. The maximum longitudinal stress, 234±7.7 MPa is reached at z = 50 mm for section V55. For sections V25 and V85, the maximum stress values are respectively 205±5.2 MPa at z = 50 mm and 218.7±5.3 MPa at z = 51 mm. No stress data are available in the middle of the deposit (z 54 mm). The one measured at z = 53 mm is in the parent's melted zone. [START_REF] Coules | Experimental measurement of biaxial thermal stress fields caused by rc welding[END_REF]. They noticed that the material developed plastic strain around the melted zone. This zone was subjected to high heating what produced high thermal gradient through the parent from its top to its inside. This strong thermal gradient produced a thermal compression of material inside of it during the heating time. During the cooling, the melted zone solidified which in turn generated a shrinkage of the melted pool zone so tensile stress while within the unmelted zone of the parent was subjected to compressive stress. Table 2: Longitudinal stress values along the vertical axis for the three sections.

A 2D field of the longitudinal stresses is displayed in figure 6. All scanned lines with some extra points added to a interpolation function allowed to plot this field within the 1 layer specimen. The compressive zone is clearly visible inside the parent and represents a wide part of the parent. The longitudinal stress peaks are located at the parent / deposit interface as already mentioned. The bottom part of the specimen experiences tensile stress. It is supposed to be a result of a stress balance within the specimen.

Comparison of residual stress distributions in both specimens

The 2 nd layer was deposited such that the end of the previous layer was its starting point. A on a warmer specimen, especially on a warmer surface. The temperature was monitored with a Ktype thermocouple of 0.5 mm diameter located in section V55, 3 mm below the parent top surface. At the beginning of the 2 nd layer, the recorded temperature was close to 300 • C while the initial parent temperature before the deposition of the 1 st deposit was close to 20 • C. The second thermal cycle (heating then cooling phases) generated during the deposition of the 2 nd layer did not produce a strong material compression during the heating phase. Furthermore, the 2 nd layer started where the specimen was the hottest and finished where it was the "coldest". This is probably why there was no change in the compressive zone. The minimum longitudinal stress value did not change significantly nor its position within the parent. The compressive zone inside the parent became a little be larger. It was also observed that the melted pool was longer during the deposition of the 2 nd layer. The re-melting of one part of 1 st of the deposit led to a reset of the stresses in this zone (the melted pool is often supposed to undergo low stresses). During the solidification, this longer melted zone shrinked again but under different thermal conditions as well. Indeed, the 2 nd cooling rate, estimated to 8.4 • C/s, was also lower than the 1 st one, estimated to 11.2 • C/s. The lower cooling rate likely acted as heat treatment and produced a slight stress relief nearby the 2 nd melted zone. The north american stainless steel recommends stress relief heat treatment for SS316L in the range [570 • C -830 • C] up to 60 min. The thermocouple located at z = 50 mm (so 3 mm under the parent's top surface) varied exactly in this temperature range but for a shorter duration (45 s). Real Heat treatment procedure (700 • C for 2 hours) of Additive Manufactured SS316L part made with Laser Bead Powder process has reduced the tensile stresses [START_REF] Williams | Effects of Heat Treatment on Residual Stresses in the Laser Powder Bed Fusion of 316L Stainless Steel: Finite Element Predictions and Neutron Diffraction Measurements[END_REF]. Despite the shorter duration of this zone, the second thermal deposition cycle has probably decreased the tensile stresses nearby the melted zone what also induced a decrease of tensile stress in the parent's bottom.

Conclusion

In this communication, residual stress fields into one layer and two layers specimens have been presented. This work aims to understand the generation of the stresses during wire and arc additive manufacturing especially to understand the effect of the next deposit on the residual stresses resulting of the 1 st deposit. The residual stresses were measured with the neutron diffraction technique at the SALSA beamline, Institut Laue Langevin, in Grenoble (France). The neutron diffraction measurements provided valuables data. The one layer specimen has been neutron scanned along few lines what allowed to do a 2D map of the longitudinal and transverse stresses in the specimen. The two layer specimen was only scanned along one line. Then the residual stresses for both specimens were compared along the same line. It appeared that the 2 nd thermal cycle occuring during the deposition of the 2 nd layer produced a partial stress relief nearby the melted zone. After the 1 st deposition of the layer, this zone exhibited high longitudinal tensile stresses up to 234 MPa while the longitudinal stress decreased to 173 MPa after the deposition of 2 nd layer. This trend is interesting as it may be used to lower the tensile stresses within an Additive Manufactured part by controlling some process parameters : welding current, voltage and speed and the cooling time between two deposits.

Figure 1 :

 1 Figure 1: Geometry of the specimen with 1 deposited layer on its thickness and scanning lines used for neutron diffraction.

Figure 2 :

 2 Figure 2: Specimen with two layers. The white dash dotted lines was the only line used for neutron diffraction measurements.

Figure 3 :

 3 Figure 3: principal direction of grains in the five layers specimen (TD is the transverse direction and ND normal direction). Investigated specimen labelled 21 11 19.

Figure 4 :

 4 Figure 4: principal direction of grains in the five layers specimen (TD is the transverse direction and ND normal direction). Investigated specimen labelled 21 11 19.

Figure 5 :

 5 Figure 5: longitundinal stress for L1 at the three sections.

Figure 6 :

 6 Figure 6: 2D longitudinal stress field within the one layer specimen.

Table 1 :

 1 process parameters used for deposition of the layers. The shielding gas used was a mixture of 98 % Argon with 2% Carbon Dioxyde (CO 2 ) at flow rate of 15 L/min.

	parameter U (V) I (A) V (mm/s) Ws (m/mn)
	1st layer	13.4	123	7	4.2
	2n layer	13.3	110	7	3.3

corresponding author: sebastien.rouquette@umontpellier.fr

Acknowledgements

The authors wish to acknowledge the scientific support and technical from Sandra CABEZA of the institute Max von Laue -Paul Langelin, SALSA beam line.

cooling time of 35 s was also applied before starting the 2 nd deposit. Indeed, this cooling was not enough for the specimen to get back to the ambient temperature. The comparison of longitudinal stresses is given in figure 7. The two longitudinal stress distributions are similar in the half bottom of the parent (z < 31 mm) even if the tensile stress reached at the bottom (z = 1 mm) is lower after 2 deposits with a value of 104.8 ± 4.6 MPa as reported in table 3. In the top half part of the specimen, the longitudinal stress distributions follow the same trend but the values of the 2 layers specimen are lower. The highest stress value is 173 MPa reached at z = 53 mm so 2 mm under the interface between the 1 st and 2 nd layers. This value is about 60 MPa lower than the one measured for the 1 layer specimen at z = 50 mm (3 mm under the interface parent / deposit). The longitudinal stresses decreases slowly to the top deposit surface as a value of 137. The two transverse stress distributions are presented in figure 8. These distributions are very similar from the parent's bottom to the deposits's top. As the plane stress assumption used for estimating the reference 2θ 0 angle imposed that σ norm = σ Y Y = 0 and the transverse stress values are almost constant and close to zero, the mechanical loading, at section V55, is almost uni-axial.

4 Discussion: effect of the 2 nd layer deposition on residual stresses

The deposition of the 2 nd layer had led to a decrease of the maximum longitudinal stress values without modifying the minimum one. The decrease of tensile longitudinal stresses is significant: up to 60 MPa in the melted zone and up to 100 MPa at the parent's bottom. The 2 nd layer was deposited 35 s after the previous one was finished and its starting point was where the previous one ended up. The specimen did not get enough time to reach the initial temperature so the 2 nd layer was deposited