Daniel Roger
email: daniel.roger@univ-artois.fr

Mathieu Rossi
email: mathieu.rossi@univ-artois.fr

Krzysztof Komeza
email: krzysztof.komeza@p.lodz.pl

Jérôme Cambier
email: jerome.cambier@securelecsocem.com

Design of coils for high-power medium-frequency transformers using Grain-Oriented hot cores

Keywords: Solid-State Transformer (SST), medium frequency transformer (MFT), foil coils, grain oriented electrical steel

This article proposes a design of windings for medium-frequency transformers (MFTs) at the heart of highpower Solid-State Transformers (SSTs). With aluminum interleaved foils of the correct thicknesses, it is possible to obtain low winding losses and a very low leakage inductance well adapted to SSTs. The magnetic phenomena are analyzed by a 2D FEM model obtained connecting in series 4 sub-models describing specific parrs of foil coils. The proposed winding avoids Litz windings, which are significantly more expensive. On the other hand, the high capacitance between foils yields a good distribution of the electric field inside a winding fed by fast fronts voltage pulses.

I. INTRODUCTION

With more and more renewable intermittent sources, the grid stability becomes more challenging because the large adjustable power stations take a decreasing part. The meshed distribution grid stability can be improved by smart nodes controlling the bidirectional energy flows at the grid's critical nodes in real time. High-power Solid-State Transformers (SSTs) can perform this function. The central elements of such SSTs are medium or high frequency transformers. The standard solution consists in designing such transformers around ferrite or nanocrystalline cores with Litz-wire coils [START_REF] Elrajoubi | High-Frequency Transformer Review and Design for Low-Power Solid-State Transformer Topology[END_REF]. High-power SSTs are often made of many elementary cells. It is also possible to design high-power MFT (several MVA) with wound cores made of grain-oriented electrical steel (GOES) thin strips. This material can withstand high temperatures; this property is used for reducing core losses [START_REF] Ichou | Assessment of a grain oriented wound core transformer for solid state converter[END_REF][START_REF] Roger | Solid-state transformers of smart high-power battery charger for electric vehicles[END_REF]. High-power SST applications often operate at high voltages; a specific conception of windings, able to withstand high-voltage fast-fronted pulses is necessary. The paper proposes a winding design that offers the low leakage inductance and the high-voltage capability required for highpower SSTs.

II. HOT-CORE TRANSFORMER STRUCTURE

The schematic structure of the hot-core transformer is presented in Fig. 1. There is no contact between the core and the coils, which are fixed between the upper and lower supports that are not shown in this schematic structure. Fresh airflows (green arrows), provided by small fans, allows the cohabitation of a hot core inside coils at usual temperatures. Accepting reasonably high core temperatures, this transformer can operate at high flux densities up to 4 kHz. In these conditions, specific power is high and the efficiency in the same range than standard SSTs.

III. WINDING DESCRIPION

The primary and the secondary coils are made with two interleaved aluminium foils whose thicknesses are 1 mm. The aluminium foils are insulated by a 200 μm thick polymer. In Fig. 2, the 14-turn secondary coil is drawn in blue and the 10turn primary coil in red, between turns 2 and 12 of the secondary coil. With large aluminium foils and a thin polymer layer, the capacitances between turns are higher than for standard coils made with Litz wires. The over-voltages due to the high slew rate rectangular pulses are limited. With this winding technology such MFTs can be associated to high-voltage IGBT bridges able to reach powers in the 10 MW range. This structure can also operate up to the thermal class of the polymer sheet that separates the foils (200°C for a class C polymer), which is higher than for Litz wires.

IV. DETERMINATION OF THE LEAKAGE INDUCTANCE

Figure 3 presents a high-power SST that connects two DC smart grids. The MFT is placed between two active bridges. The power transferred between the input and output is controlled by the phase shift φ between the command of the two bridges [START_REF] Gu | Modeling and Control of a Multiport Power Electronic Transformer (PET) for Electric Traction Applications[END_REF]. In (1), VA and VB are voltages of the two smart grids, ω is the angular frequency, and LL is the leakage inductance of the TMF referred to the primary side. This equation shows that the leakage inductance LL must be as low as possible for transfering high powers.

𝑃 = 𝑉 ! 𝑉 " 𝜋𝜔𝐿 # 𝜑(𝜋 -|𝜑|) (1)
A transformer is a three-dimensional object; a significant part of the winding is outside the core windows; this observation must be considered in the FEM analysis. The 3D model of such an object requires too many nodes because the foil thickness must be split into several layers for modelling the skin and proximity effects. A specific 2D model, with a reasonable mesh is proposed. This model it is made of a series connection of 4 sub-models (Fig. 4). The first sub-model considers the two straight parts of the winding inside the core windows. The second one describes the straight part of the coil end with the primary connection bars. The third one represents the front part with the secondary connection bars that impose a different air-layer between several foils. The fourth part describes the 4 circular parts that connect the straights parts. Boundary conditions are defined on specific lines separate the sub-models. The foil thickness is split into 7 layers for obtaining at least 3 elements in the skin depth at 4 kHz. It should be emphasized that this low leakage inductance is obtained thanks to the full interlacing of the windings. For concentric classical windings, the leakage inductance is about 30 times higher (Fig. 6). This very good result is obtained with a slightly more complicated winding construction. For the interlaced winding, the inductance value is very sensitive to the spacing between foils. For the considered model, an increase the spacing between foils by 0.2 mm (double insulation thickness) increases the inductance by 18%.

V. CONCLUSION

The article presents a high-power MFT operating at 4 kHz using a GOEs wound core and foil windings. The transformer design assumes that the core will operate at high temperatures for reducing eddy current losses. The design of the foil windings requires an analysis of the field phenomena that corresponds to skin et proximity effects. A construction with interlaced primary and secondary coils yields a very low leakage inductance at the operating frequency.

Fig. 1 .

 1 Fig. 1. Hot-core transformer structure.

Fig. 2

 2 Fig. 2 Interleave foil coils providing a low leakage inductance.

Fig. 3

 3 Fig. 3 Example of a high-power SST connecting two DC smart grids.

Fig. 4

 4 Fig. 4 Transformer 2D model that consists of a series connection of 4 submodels representing specific parts of the foil coils of the transformer.

Figure 5

 5 Figure 5 presents an example of the current density distribution inside a 1 mm thick aluminium foil. Because skin and proximity effects, the leakage inductance decrease with frequency. The change is about 5% between 1 kHz and

Fig. 5

 5 Fig. 5 Example distribution of the instantaneous value of the current density (A/mm 2 ) in the cross-section of the foil (deformed dimensions).

Fig. 6

 6 Fig. 6 Left: flux density magnitude for concentric coils. Right: Flux density magnitude for interlaced coils.


Identifying profiles of patients to personalise BCI-based procedures for motor rehabilitation after stroke

Elise Grevet, Margaux Izac, Léa Pillette, F. Amadieu, D. Gasq, Jacques Py,

Camille Jeunet-Kelway

To cite this version:

Elise Grevet, Margaux Izac, Léa Pillette, F. Amadieu, D. , but this efficiency has not reached yet the level required to achieve a clinical usage. We hypothesise that improving BCI acceptability, notably by personalising BCI-based rehabilitation procedures to each patient, will reduce anxiety and favour engagement in the rehabilitation process, thereby increasing the efficiency of those procedures. To test this hypothesis, we need to understand how to adapt BCI procedures to each patient depending on their profile. Thus, we constructed a model of BCI acceptability based on the literature [3], adapted it in a questionnaire, and distributed the latter to post-stroke patients (N=140).

Methods:

The questionnaire consisted of i) 3 target factors used as a proxy of BCI acceptability, namely the perceived usefulness (PU), perceived ease of use (PEoU) intention to use (IU) and ii) 23 explanatory factors that could influence acceptability. First, k-mean clustering analyses were performed to identify different profiles of patients. Then, for each cluster, elastic net regressions were used to identify the explanatory factors that predicted PU, PEoU and IU the best, i.e., to identify the factors that are the most important to personalise for each patient.

Results: Five clusters (c1 to c5) were identified. The regression analyses indicated that the following factors had to be considered: (c1 & c5) "scientific relevance" & "ease of learning"; (c2) "benefits/risks ratio", "ease of learning", "visual aesthetic" & "result demonstrability"; (c3) "scientific relevance" & "benefits/risks ratio";(c4) none.

Perspectives: We will use those results in a clinical study to personalise the BCI procedures to each patient. We expect lower anxiety and better motivation, acceptability and motor recovery with this personalised setting than with a standard one.

Sources

[ 1 ]

 1 Inserm, 2019 [2] Cervera, María A., et al. "Brain-computer interfaces for post-stroke motor rehabilitation: a meta-analysis." Annals of clinical and translational neurology 5.5 (2018): 651-663. [3] Blain-Moraes, Stefanie, et al. "Barriers to and mediators of brain-computer interface user acceptance: focus group findings." Ergonomics 55.5 (2012): 516-525.

  Stroke leaves around 40% of surviving patients dependent in their activities, notably due to severe motor disabilities[1]. BCIs have been shown to favour motor recovery after stroke[2]

	Acceptability of BCI-based procedures for motor rehabilitation after stroke: A questionnaire
	study among patients
	Authors : Elise Grevet, Margaux Izac, Léa Pillette, Franck Amadieu, Jacques Py, David Gasq, Camille Jeunet-
	Kelway

Gasq, et al.. Identifying profiles of patients to personalise BCI-based procedures for motor rehabilitation after stroke. CORTICO 2023 -Annual meeting de COllectif pour la Recherche Transdisciplinaire sur les Interfaces Cerveau-Ordinateur, CORTICO, May 2023, Paris, France. pp.1-1. hal-04288958 Introduction:


domain: sdv spi

text:
Background: Fracture risk prediction in patient relies chiefly on bone mineral density (BMD) measurement. However, the decreased bone strength characteristic of osteoporosis is dependent not only on BMD, but also on other factors, most notably bone microarchitecture.

Objectives: The purpose of this study was to investigate bone microarchitecture variables of cadaveric vertebrae using ultra-high field MRI (7 Tesla). Methods: Twenty four vertebrae (L2, L3, L4) from eight cadavers were studied using 7 Tesla MRI. Their Bone Mineral Density (BMD) were investigated using dual energy X Ray absorptiometry. Then, all specimens underwent mechanical compression tests to failure and the failure load (in Newton) and constraint (in Mpa) were measured. Bone Volume Fraction (BV/TV), Trabecular Thickness (Tb.Th), and Trabecular Spacing (Tb.Sp) were measured in MR images using a Digital topological analysis (Bone J). Measurements were performed by two observators in order to characterize the inter-rater reliability. Statistical analyses were performed using SPSS. Correlations between variables were analyzed using Spearman correlations and Stepwise regression. A p value of 0.05 was considered as significant.

Results:

The inter-rater reliability for bone microarchitecture parameters quantification was good. Tb.Th and Tb.Sp measured using high-field MRI were 0.52±0.18 and 0.48±0.10 respectively while the BV/TV fraction was 0.52±0.13. The mean BMD was 0.86±0.20 g/cm 2 . The failure load and the constraint measured during the compression tests were 2600±1267N and 1.57±0.81 Mpa respectively. Interestingly, the variables measured during the mechanical tests were significantly

The failure load and constraint measured during the compression tests were significantly correlated with the BMD. Regarding the bone indices quantified using high-field MRI, a significant linear relationship was observed between the trabecular spacing and the BMD (R 2 =0.23, p=0.01 and the constraint values to failure (R 2 =0.18, p=0.04). A stepwise regression with backward elimination demonstrated that combining BV/TV and BMD improved the relationship with the constraints from an adjusted R 2 =0.384 for BMD alone to an adjusted R 2 =0.41 for BMD + BV/TV.

Conclusions:

In the present study, we demonstrated for the first time that the variables characterizing the vertebral bone microarchitecture quantified using ultra-high field MRI were significantly correlated with biomechanical parameters.

In addition, we illustrated that the vertebral bone strength was better described by a variable combining BMD and trabecular bone spacing. Background: Several clinical remission (CR) criteria of rheumatoid arthritis (RA) contain acute-phase reactants [C-reactive protein (CRP), and erythrocyte sedimentation rate (ESR)] as their components. However, it is known that they can be underscored by the usage of tocilizumab (TCZ). This may cause overestimation of CR. On the other hand, ultrasound sonography (US) provides objective information independent of acute-phase reactants and assessment by physician and patient, and can detect synovitis in RA patients in CR, which is called sonographic residual synovitis (SRS). Objectives: To assess whether CR of TCZ-using RA patients are overestimated, by using US. Methods: We recruited 402 RA patients. Bilateral 2-5 MCP, wrist, ankle, and 2-5MTP joints were scanned by using the Aplio500 (TOSHIBA) with a 12 MHz transducer. Power Doppler (PD) images were obtained by Superb Micro-vascular Imaging (SMI). Gray scale (GS) and PD images were scored using a 0-3 semiquantitative scale. Clinical information was obtained from the Kyoto University Rheumatoid Arthritis Management Alliance (KURAMA) database, which is based on the assessments by physicians who were blind to the US results. The patients were divided into 4 groups based on their treatment: tumor necrosis factor alpha inhibitors (TNFi), TCZ, abatacept (ABT), and non-biologic (non-Bio) users. Two patients treated by tofacitinib were excluded because the number was too small to analyze. The Boolean (BL)-based, Simplified Disease Activity Index (SDAI)-based, Clinical Disease Activity Index (CDAI)-based, and Disease Activity Score (DAS)28-ESR-based CR criteria were assessed using SRS. Results: A total of 400 RA patients were analyzed. The number of patients in each treatment group is shown in the Table . When the BL-based, SDAI-based, and DAS28-ESR-based CR criteria were used, SRS in TCZ group was significantly stronger than the other groups (Fig 123). On the other hand, when CDAI-based CR criteria was used, the difference was not significant among 4 groups (Fig

  Guis 1 , D. Guenoun 2 , A. Fouré 3 , M. Pithioux 4 , T. Le Corroller 2 , J.P. Mattei 1 , V. Pauly 5 , M. Bernard 3 , P. Chabrand 4 , P. Champsaur 2 , D. Bendahan 3 . 1 Rheumatology 1; 2 Radiology, Aix Marseille Université, AP-HM; 3 CRMBM, UMR 7339; 4 Ism UMR 7287, CNRS; 5 Statistic department, AP-HM, Marseille Cedex 9, France

	Friday, 16 June 2017	Scientific Abstracts
	FRI0671 ULTRA-HIGH FIELD MRI AND BIOMECHANICAL
	INVESTIGATION OF VERTEBRAL BONE
	MICROARCHITECTURE
	S.

ASSESSMENT OF THE NAIL BED IN PSORIATIC ARTHRITIS (PSA) BY ULTRASOUND (US) AND MRI

  PsA can be difficult to distinguish from osteoarthritis (OA) and the treatments vary greatly. Nail involvement can occur in about 15-50% patients with psoriasis 1 , which may aid differentiation from OA. If US can reliably detect nail bed changes in early disease then it might be helpful in differentiating PsA from OA Objectives: This study aims to investigate the nail bed changes seen in patients with PsA and OA using US and MRI, and to determine the impact of nail bed changes on quality of life (QOL). ) in the nail bed, nail matrix and dermis, and assigned a total PD score. All patients had an MRI of the dominant 2nd to 5th finger.

	Methods: Patients who fulfilled the CASPAR PsA or 1990 ACR OA classification criteria were recruited. At baseline, clinical assessment included patient and physician's visual analogue scale (VAS), tender and swollen joints, patient's Leeds Enthesitis Index and quality of life specific to nail psoriasis (NPQ10). Nail abnormalities on the dominant hand such as onycholysis, pitting, nail bed hyperkeratosis and nail bed crumbling were documented. Using US, each nail (1-5) was scored dichotomously for pitting/irregularity, loss of normal trilaminar appearance of the nail. Each nail was scored semi quantitatively for power doppler (PD) signal (0-3Table 1 Age (median (IQR)) Patient VAS (median (IQR)) Physician VAS (median (IQR)) NPQ10 (median (IQR)) Swollen joint count (median (IQR)) Leeds Enthesitis index (median (IQR)) Percentage of nails with clinical abnormalities Percentage of nails with US structural abnormalities Percentage of nails with PD signal Conclusions: In this small prospective study, structural abnormalities detected by Total (n=14) PsA (n=10) OA (n=4) 56.5 (52.2-63.2) 55.0 (48.0-63.2) 61.0 (55.2-73.5) 29.0 (12.5-54.8 39.5 (19.8-54.8) 11.0 (3.8-54.2) 35.3 (20.5-57.5) 42.5 (24.5-57.5) 24.0 (4.8-53.8) 6.5 (1.8-10.0) 7.0 (5.2-10.2) 1.5 (0.2-5.8) 2.0 (0.0-4.2) 1.5 (0.0-5.2) 2.5 (0.5-5.8) 1.0 (0.0-2.0) 1.0 (0.0-2.0) 0.5 (0.0-1.8) 27.7% 40.0% 0.0% 44.3% 54.0% 20.0% 97.1% 96.0% 95.0% US appear to correlate well against clinical structural findings, but PD signal does not. No relationship was found between US findings and other clinical parameters. US structural abnormalities may be a better differentiator of PsA and OA than PD signal. MRI validation of these results is pending. References: [1] Gisondi P, Idolazzi L, Girolomoni G. Ultrasonography reveals nail thickening in patients with chronic plaque psoriasis. Arch Dermatol Res 304:727-732,2012. Acknowledgements: This study was funded by a grant from UCB Australia Pty Ltd. Disclosure of Interest: None declared DOI: 10.1136/annrheumdis-2017-eular.5614 FRI0673 CLINICAL

Disclosure of Interest: None declared DOI: 10.1136/annrheumdis-2017-eular.2034 FRI0672 S. Paramalingam 1 , A. Taylor 2 , H. Keen 2,3 . 1 Rheumatology, Sir Charles Gairdner Hospital; 2 Rheumatology, Fiona Stanley Hospital; 3 School of Medicine, University of Western Australia, Perth, Australia Background: Results: 14 patients were recruited; demographics, clinical and US detected nail changes are documented in Table

1

. Clinical nail changes were not seen in the OA group, but were relatively common in the PsA group. In the PsA group, 54% of nails had US detected structural abnormalities; 12% pitting and 52% loss of trilaminar layer. Only 20% of OA nails had US detected abnormalities. There was a strong relationship between the presence of clinical nail change and US structural changes (chi square 10.769 df 1 p=0.001) but not PD signal score. There was no relationship between clinical or US detected nail scores and NPQ10, patient or physician VAS, swollen joint count or Leeds Enthesitis Index. MRI analysis is pending.

REMISSION IN TOCILIZUMAB-USING RHEUMATOID ARTHRITIS PATIENTS CAN BE OVERESTIMATED: A CROSS SECTIONAL STUDY USING ULTRASOUND SONOGRAPHY S

  . Nakabo 1 , Y. Tsuji 2 , M. Inagaki 2 , H. Tsuji 1 , T. Nakajima 1 , M. Hashimoto 3 , M. Furu 3,4 , M. Tanaka 3 , H. Ito 4 , T. Fujii 1,5 , Y. Fujii 2 , T. Mimori 1 . 1 Department of Rheumatology and Clinical Immunology; 2 Human Health Sciences Clinical Physiology and Ultrasound Labo; 3 Department of the Control for Rheumatic Diseases; 4 Department of Orthopaedic Surgery, Graduate School of Medicine, Kyoto University, Kyoto; 5 Department of Clinical Immunology and Rheumatology, Wakayama Medical University, Wakayama, Japan


domain: phys spi

text:
I Bel-Hadj
email: ibrahim.bel-hadj@univ-lille.fr

Z Bougrioua
email: zahia.bougrioua@iemn.fr

K Ziouche
email: katir.ziouche@univ-lille.fr

IC-AIRES2022

Keywords: Energy harvesting, thermoelectrics, micro-generator, planar, Silicon technology, thermal modeling. I

In this work, we present our novel planar micro-thermoelectric generators (µTEGs) integrating an original "folded" thermopile topology, periodically distributed on suspended membranes. The thermopile integrates eco-friendly and low-cost materials as Constantan (Cu45Ni55) and Chromel (Ni90Cr10) that build up thermocouples associated both in series and in parallel. This dual association allows to drastically reduce the thermopile electrical resistance (down to a few tens to a few hundred ohms) and so to electrically better adapt them. To optimize the structural dimensions of the µTEG, numerical simulations have been performed by 3D-finite element modeling using COMSOL Multiphysics© software. Several µTEG modules integrating this folded thermopile have been manufactured using Silicon micro-technologies that differ from our former expertise. In 3-membrane-based modules the harvested output power can reach 108 µW/cm² (for 1 W heat injected into the µTEG) with an output voltage up to few hundred of millivolts, which is enough to supply micro devices for IoT applications.

INTRODUCTION

Numerous technologies of the future such as smart-energy management (İcan and T. B. Çelik., 2021) but also smartcity development (A. [START_REF] Sampathkumar | Advanced Energy Management System for Smart City Application Using the IoT[END_REF] will undoubtedly rely on the Internet of Things (IoT). Even though, applications of IoT are growing at a rate never seen before (IoT Analytics., 2022), these ones are delayed by the lack of energy solutions to supply them with no maintenance requirement as for instance the need of battery replacements. Thus, all innovative solutions contributing to improve the renewable production of energy are playing a strategic role and many of them consist to harvest energy from the direct environment to produce electricity and supply the IoT nodes (H. [START_REF] Sun | MEMS based energy harvesting for the Internet of Things: a survey[END_REF]. Due to the abundance of heat, micro ThermoElectric Generators (µTEGs) have become an actual promising solution. The active part of these devices is mainly made up of the association of a set of thermocouples (TCs) generally connected in series electrically and in parallel thermally (D. M. [START_REF] Rowe | Thermoelectrics handbook: macro to nano[END_REF]. Their working principle is based on the Seebeck effect (T. J. Seebeck, 1821) corresponding to the conversion of temperature gradients into electrical voltage.

The performances of µTEGs are generally related to the nature of TE materials but also to their geometrical structures that can be classified in two main categories: vertical or planar configurations (Fig 1). Vertical configurations provide more power and often use better performing TEs such as Bismuth and Antimony alloys (G. J. Snyder and E. S. Toberer., 2008). However, these materials are expensive to develop, incompatible with Silicon technologies and are highly toxic. Planar structures, generally using thin TE films, present the advantage of allowing the thermal adaptation of µTEGs to their environment due to their high and adjustable thermal resistance (Z. [START_REF] Yuan | A planar micro thermoelectric generator with high thermal resistance[END_REF]. This paper presents first results of such μTEGs that use a new thermopile topology made of Ni90Cr10 (Chromel) and Cu55Ni45 (Constantan) based TEs integrated in an original topology periodically folded and distributed on a multi-membrane template. Two configurations of the µTEG, with 2 and 3 membranes, are designed and modeled using COMSOL Multiphysics® software, and are afterward fabricated using CMOS-compatible Silicon technology. The fabricated modules were tested under calibrated heat flux to measure the Seebeck voltage and the output power for various heat input. • The first part (bottom part) is made of a set of membranes hollowed out and released in a Si substrate (380 µm thick (100) oriented Si). These periodically etched membranes are build up with a low-stress SiO 2 /Si x N y bilayer, obtained by stress compensation of the two layers of 800 and 600 nm (M. Hafar, 2007) which limits bowing events and contribute to the mechanical strength of the whole structure. An innovative thermopile based on Cu55Ni45 and Ni90Cr10 TCs is designed with an original topology, "periodically folded", and distributes perpendicularly on the multimembrane template. The details of the design and the fabrication steps of the thermopile were described in I.

IC-AIRES2022

down towards the heat sink, through the membranes (the pillar contacts with the membranes are located at the hot junction places of the thermopile). Four mechanical supports (bosses) located at the 4 corners of the concentrator are used to ensure a rigid support of the concentrator on the substrate and avoid the breaking of the membranes. So one part of the incident heat flux that is lost through the 4 bosses (i.e., without passing through the membranes): this part is directly proportional to the total contact surface between these bosses and the heat sink wafer. This contact surface must be as small as possible to minimize these lateral losses. But a compromise must be made in order not to weaken the µTEG too much (surface too small), experimentally, this surface was fixed at 1.2 mm 2 .

The heat concentrator will be aligned on the suspended membranes such a way that the pillars are centered over the middle of the membranes. This is performed under optical microscopy using alignment wedges. Thermal grease is used to ensure a good wet contact between concentrator pillars and membranes and minimize thermal contact resistance.

III. RESULTS AND DESCUSSION

A. 3D THERMAL MODELING

To predict the temperature distributions across the µTEGs structures and the temperature gradients between the TC's junctions, the 3D structure of the µTEG is modeled using COMSOL Multiphysics® software, based on the finite element method. The description of the model and the simplifying computational assumptions as well as the boundary conditions on which the µTEG is submitted are detailed in I. The simulation results corresponding to the applied boundary conditions, allow to calculate that the temperature differences generated between the hot and cold junctions ∆ , are 137 K and 120 K and those between the surface of the concentrator and the heat sink ∆ , are 142 K, 126 K, respectively for the 2 and 3-membranes µTEGs. The percentages of the fluxes exchanged by convection, radiation and that lost through the bosses are respectively of 11%, 5% and 37% for 2-membranes µTEG and of 9%, 4% and 33% for 3-membranes µTEG.

To optimize the structural dimensions of the µTEG, simulations have been carried out for modules integrating up to 10 membranes. These studies will be presented in an upcoming paper.

IC-AIRES2022

B. CHARACTERIZATION OF THE µTEGS

The two fabricated devices (2 and 3-membranes µTEGs) were tested using a four-probe set-up over a heat input range of 0 -1.2W. The measurement principle consists in injecting a calibrated heat input by Joule effect in the heater (resistance in gold realized directly upon the surface of the concentrator as seen in The maximum output power density generated by the µTEG (corresponding to the power generated to a matched load resistance) can be calculated using the measured Seebeck voltage by:

IC-AIRES2022

= µ where is the internal electrical resistance of the µTEG (305 Ω and 140 Ω respectively for 2 and 3 membranes µTEG). We note that the internal resistances of this new family of µTEGs with an all-metal thermopile, are clearly lower than those of the first generation modules, based on a periodically plated poly-Silicon thermopile, for whom were of the order of a few hundred kΩ to a few MΩ for modules with 2 membranes (Z. [START_REF] Yuan | A planar micro thermoelectric generator with high thermal resistance[END_REF]. is the external temperature difference between the two heat sources in which the device is placed) of about 6.82 × 10 -3 µW.cm -2 .K -2 when the ∆ is about 126 K which correspond to 1W of heat injected into the concentrator. These performances are much better than of state-of-the-art modules using metallic thermoelectrics (for instance see Y.

IV. CONCLUSION

In this study, we have presented a novel planar µTEG for thermal energy harvesting. The technology implemented is based on an original folded thermopile topology periodically distributed onto suspended membranes. The thermopile integrates metallic TE materials based on Cu55Ni45 and Ni90Cr10 that build up thermocouples associated both in series and in parallel. The use of metallic TE materials allowing to reduce the internal electrical resistance of the µTEGs compared to our first generation based on polysilicon thermopile. The fabrication of these devices is implemented using CMOS-compatible process of microfabrication. For 1 W heat injected into the heat concentrator, the maximum power is 108 µW/cm² with an efficiency factor of 6.82 × 10 -3 µW.cm -2 .K -2 for µTEG configurations with 3 membranes. These first results will be followed by other studies to improve the performances of these µTEGs.

  structure of the planar µTEG proposed in this work (total area µ ~ 6 mm × 5.7 mm) is mainly composed of two parts (Fig 2) made up of two etched Silicon (Si) wafers:

Fig. 1 .Fig. 2 .

 12 Fig. 1. The two typical µTEG structures: (a) vertical (π), (b) planar.

  Bel-Hadj et al. (2022). The symmetry of the structure allows to model only half of the µTEG, in order to reduce the calculation time and memory requirements. The Fig 3 shows an illustration of the temperature distribution simulated for the half structures of µTEGs with 2 and 3 membranes. A heat flux density of 3.3 W/cm² is applied on the surface of the concentrator (surface ~ 0.3 cm²), corresponding to a net input heat of 1 W. A part of the input heat is lost by natural convection and radiation between the surface of the concentrator and the ambient environment. Another part is lost through the bosses. The temperature of the bottom surface of the heat sink is set at 25°C (equal to the ambient temperature). The heat flow through the pillars of the concentrator, towards the membranes, creates periodic temperature gradients between the junctions of each TC constituting the thermopile, as shown in Fig 3.

Fig. 3 .

 3 Fig. 3. Temperature distribution calculated for 2-and 3-membranes µTEGs. An input power of 1 W is injected into the concentrator and the temperature of the bottom side of the substrate is kept at 25 °C.

Fig 2 )Tab. 1 .

 21 with two probes, and measuring with the two other probes the Seebeck voltage generated from the device. The characteristics of the µTEG configurations realized and characterized in this work are presented in Tab 1. All these modules have an identical footprint ( µ ); the only difference is the number of thermocouples and membranes (and the number of concentrator pillars) depending of the length of the thermoelements. Concerning the thicknesses of TE materials, the both modules have 150 nm of Ni 90 Cr 10 and 450 nm of Cu 55 Ni 45 . Main parameters of the 2 fabricated and characterized µTEG configurations.Each µTEG is characterized several times by adjusting the alignment between the concentrator and the bottom part of the module. The Fig4shows the best measured Seebeck ( ) voltage generated from the both devices as a function of the heat injected into the concentrator. increases linearly with increasing heat input and reach a maximum of about 201.6 mV obtained by the µTEG with 2 membranes for a maximum injected heat input of 1.2 W. The linear characteristics of the Seebeck voltage as a function of the input power are naturally explained by Seebeck effect:= ∆ =where is the number of TCs connected in series fixed by the stripe width ( =25 for a stripe width of 200µm), = ( -) is the equivalent Seebeck coefficient of a TC, ∆ = is the effective temperature difference between the hot and cold junctions, is the internal thermal resistance of the µTEG, and is the input power injected into the concentrator. The dependence of the Seebeck voltage on the thermal resistance of the µTEG, which depends on the number of membranes (fixed by the length of the TCs, see Tab 1) explains the differences between the Seebeck voltages delivered by the both µTEG configurations.

Fig. 4 .

 4 Fig. 4. Seebeck voltage generated by 2 and 3-membranes µTEGs versus input power injected into the concentrator.

Fig 5

 5 Fig 5 shows the maximum output power density () generated by the µTEGs as a function of the input heat injected into the concentrator. The maximum generated output power density is about 125 µW/cm 2 for an injected input power of ~ 1.07 W obtained with 3-membranes µTEG. Normalized to 1W of injected input power, this is equivalent to the output power of 108.3 µW/cm². This corresponds to an efficiency factor[START_REF] Strasser | Micromachined CMOS thermoelectric generators as on-chip power supply[END_REF]) defined by ∆ ⁄ (where ∆ is the external temperature difference between the two heat sources in which the device is placed) of about 6.82 × 10 -3 µW.cm -2 .K -2 when the ∆ is about 126 K which correspond to 1W of heat injected into the concentrator. These performances are much better than of state-of-the-art modules using metallic thermoelectrics (for instance see Y. Shimizu et al. 2018 and B. Iezzi et al. 2017).

  Fig 5 shows the maximum output power density () generated by the µTEGs as a function of the input heat injected into the concentrator. The maximum generated output power density is about 125 µW/cm 2 for an injected input power of ~ 1.07 W obtained with 3-membranes µTEG. Normalized to 1W of injected input power, this is equivalent to the output power of 108.3 µW/cm². This corresponds to an efficiency factor[START_REF] Strasser | Micromachined CMOS thermoelectric generators as on-chip power supply[END_REF]) defined by ∆ ⁄ (where ∆ is the external temperature difference between the two heat sources in which the device is placed) of about 6.82 × 10 -3 µW.cm -2 .K -2 when the ∆ is about 126 K which correspond to 1W of heat injected into the concentrator. These performances are much better than of state-of-the-art modules using metallic thermoelectrics (for instance see Y. Shimizu et al. 2018 and B. Iezzi et al. 2017).

Fig. 5 .

 5 Fig. 5. Maximum output power density generated versus input power injected into the concentrator.


Dr Mélanie Levasseur
email: melanie.levasseur@usherbrooke.ca

Marie-France Dubois

Johanne Filiatrault

Helen-Maria Vasiliadis

Joanie Lacasse-Bedard

André Tourigny

Marie-Josée Levert

Catherine Gabaude

Hélène Lefebvre

Valérie Berger

Johanne Filliatrault

Joanie Lacasse-Bédard

Chantal Eymard

Effect of Personalised citizen assistance for social participation (APIC) on older adults' health and social participation: study protocol for a pragmatic multicentre randomised controlled trial (RCT)

de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

Introduction The challenges of global ageing and the growing burden of chronic diseases require innovative interventions acting on health determinants like social participation. Many older adults do not have equitable opportunities to achieve full social participation, and interventions might underempower their personal and environmental resources and only reach a minority. To optimise current practices, the Accompagnementcitoyen Personnalisé d'Intégration Communautaire (APIC), an intervention demonstrated as being feasible and having positive impacts, needs further evaluation. Methods and analysis A pragmatic multicentre, prospective, two-armed, randomised controlled trial will evaluate: (1) the short-term and long-term effects of the APIC on older adults' health, social participation, life satisfaction and healthcare services utilisation and (2) its cost-effectiveness. A total of 376 participants restricted in at least one instrumental activity of daily living and living in three large cities in the province of Quebec, Canada, will be randomly assigned to the experimental or control group using a centralised computer-generated random number sequence procedure. The experimental group will receive weekly 3-hour personalised stimulation sessions given by a trained volunteer over the first 12 months. Sessions will encourage empowerment, gradual mobilisation of personal and environmental resources and community integration. The control group will receive the publicly funded universal healthcare services available to all Quebecers. Over 2 years (baseline and 12, 18 and 24 months later), self-administered questionnaires will assess physical and mental health (primary outcome; version 2 of the 36-item Short-Form Health Survey, converted to SF-6D utility scores for quality-adjusted life years), social participation (Social Participation Scale) and life satisfaction (Life Satisfaction Index-Z). Healthcare services utilisation will be recorded and costs of each intervention calculated.

Ethics and dissemination

The Research Ethics Committee of the CIUSSS Estrie -CHUS has approved the study (MP-31-2018-2424). An informed consent form will be read and signed by all study participants. Findings will be published and presented at conferences. trial registration number NCT03161860; Pre-results.

strengths and limitations of this study ► This innovative pragmatic multicentre, prospective, two-armed, randomised controlled trial study will generate new knowledge on impacts over a 2-year period of a promising health and social intervention designed to reduce the use of healthcare services and improve the cost-effectiveness of current practices. ► The economic evaluation will help generate evidence on the cost-effectiveness of health-promoting interventions that encourage empowerment, gradual mobilisation of personal and environmental resources and community integration in older adults. ► The composition of the team, including national and international experts, will ensure a high-quality evaluative study and optimal dissemination plan that will foster replication in other sociocultural contexts. ► Although contacts between Accompagnementcitoyen Personnalisé d'Intégration Communautaire volunteers and those who work with the control group older adults will be limited as much as possible, there is potential for contamination between experimental and control groups. ► Among other possible limitations, as the presence of cognitive impairment will be based on the coordinators' judgement rather than a standardised tool, the cognitive capacities of some participants might not be sufficient to properly understand and answer the study questionnaires.

Open Access

IntroduCtIon

Social participation is critical to promote health, prevent disabilities and foster health equity in older adults and societies 1 but is restricted for approximately half of older Canadians. [START_REF]Québec survey on activity limitations, chronic diseases and aging[END_REF] Social participation is defined as the involvement of a person in activities that provide him or her with interactions with others in the community. [START_REF] Levasseur | Inventory and analysis of definitions of social participation found in the aging literature: proposed taxonomy of social activities[END_REF] These include social and leisure activities, such as doing physical exercises, visiting friends and volunteering, that meet fundamental needs for interaction and self-accomplishment. [START_REF] Maslow | A symbol for holistic thinking[END_REF] While optimal social participation is often associated with greater community integration, at the other end of the continuum, social isolation often involves living alone, having a small social network and infrequent social contacts. [START_REF] Holt-Lunstad | Loneliness and social isolation as risk factors for mortality: a meta-analytic review[END_REF] Although, in the objective state of social isolation, a person may be isolated but prefer to be alone, in the subjective emotional state of loneliness, a person may have a good social network and participate socially but feel alone. 5 6 A meta-analysis of 148 longitudinal studies (309 000 participants) demonstrated that individuals integrated into their community had half the risk of dying within 7 years than those who lived a more solitary life. [START_REF] Holt-Lunstad | Social relationships and mortality risk: a meta-analytic review[END_REF] This protective effect is even greater than stopping smoking, vaccination, doing physical exercises, losing weight, taking hypotensive medication and breathing clean air. Although broadly targeted by community organisations, health professionals and municipalities, few effective social participation interventions really reach vulnerable populations and are implemented in practice. [START_REF] Leblanc | Pré-implantation de l'Accompagnement-citoyen personnalisé d'intégration communautaire (APIC): Adaptabilité, collaboration et financement, les déterminants d'une implantation réussie[END_REF] According to the 41 promising interventions to promote social participation that were evaluated, [START_REF] Butler | Evaluating the Senior Companion Program: a mixedmethod approach[END_REF][START_REF] Aubin | Développement de programmes visant à soutenir l'autonomie de l'intégration dans la communauté d'aînés ayant une problématique de santé mentale[END_REF][START_REF] Greaves | Effects of creative and social activity on the health and well-being of socially isolated older people: outcomes from a multi-method observational study[END_REF] including evidence from systematic reviews, 12 13 it is possible to improve self-rated health, well-being and social participation, slow cognitive and functional decline and decrease medication use and depressive symptoms in older adults. 9-11 14-16 However, among the interventions identified, only two concerned persons with disabilities, but they did not involve collaboration with community resources and were narrow, that is, focused on involvement in healthcare decision making [START_REF] Barnes | Frail bodies, courageous voices: older people influencing community care[END_REF] or restoration of a social network. [START_REF] Cheung | Contributions of Volunteer Networking to Isolated Seniors in Hong Kong[END_REF] Other interventions with volunteers targeted specific daily activities (eg, medical appointments or shopping) or physical and cultural activities to reduce loneliness. [START_REF] Chan | Effects of tai chi qigong on psychosocial well-being among hidden elderly, using elderly neighborhood volunteer approach: a pilot randomized controlled trial[END_REF] Moreover, these interventions respectively resulted more in facilitation of daily activities than older adults' empowerment and community integration, [START_REF] Butler | Evaluating the Senior Companion Program: a mixedmethod approach[END_REF] without clearly considering the effects on social participation. [START_REF] Greaves | Effects of creative and social activity on the health and well-being of socially isolated older people: outcomes from a multi-method observational study[END_REF] Interventions were also carried out in a group setting, without necessarily considering older adults' interests and needs. [START_REF] Mcnamara | Evaluation of a healthy ageing intervention for frail older people living in the community[END_REF] Previous studies emphasised the importance of and need for social interventions to foster empowerment, support the development of significant relationships and activities, be personalised and last at least 6 months in order to be effective. 12 13 To our knowledge, eight [START_REF] Stein | Effectiveness of a Service Workers' Action Team (SWAT) for the elderly[END_REF][START_REF] Andersson | Intervention against loneliness in a group of elderly women: an impact evaluation[END_REF][START_REF] Fisher | Neighborhood-level influences on physical activity among older adults: a multilevel analysis[END_REF][START_REF] Routasalo | Effects of psychosocial group rehabilitation on social functioning, loneliness and well-being of lonely, older people: randomized controlled trial[END_REF][START_REF] Kalson | A program of social interaction between institutionalized aged and adult mentally retarded persons[END_REF][START_REF] Fried | A social model for health promotion for an aging population: initial evidence on the Experience Corps model[END_REF][START_REF] Rook | Fostering social ties through a volunteer role: implications for older-adults' psychological health[END_REF][START_REF] Wikström | Social interaction associated with visual art discussions: a controlled intervention study[END_REF] randomised controlled trials (RCTs) rigorously evaluated the impact of social participation interventions, but none specifically involved older adults with disabilities. The majority (n=5; 62.5%) were carried out in the USA, with more than a thousand older adults (median=154; range=32-582) living in the community (n=6; 75.0%). All trials aimed to evaluate the impact or effectiveness of the interventions and one 21 also documented the service delivery process. Among RCTs on similar interventions with older adults with or without disabilities, Lifestyle Redesign, 28 comprising 6-9 months of preventive occupational therapy group and individual sessions empowering older adults to regularly perform healthy and fulfilling activities, has been shown to benefit physical and mental health and be cost-effective. [START_REF] Lévesque | Effets et applicabilité en contexte québécois du Lifestyle Redesign chez les aînés [Impacts and applicability in Quebec context of the Lifestyle Redesign in older adults[END_REF] Based on a logic model including theoretical background from an ecological systemic model, [START_REF] Bronfenbrenner | Ecology of the family as a context for human development: Research perspectives[END_REF] positive psychology [START_REF] Seligman | Positive Psychology, Positive Prevention, and Positive Therapy[END_REF] and occupational science [START_REF] Carlson | Practical contributions of occupational science to the art of successful ageing: How to sculpt a meaningful life in older adulthood[END_REF] and recently adapted for older adults with disabilities, preliminary studies demonstrated the feasibility [START_REF] Levasseur | Adaptation of the Personalized citizen assistance for social participation (APIC) in older adults with disabilities: a feasible intervention to foster social and leisure activities in society. Health and Social Care in the Community[END_REF] and positive impacts [START_REF] Levasseur | Personalized citizen assistance for social participation (APIC): A promising intervention Open Access for increasing mobility, accomplishment of social activities and frequency of leisure activities in older adults having disabilities[END_REF] of the personalised citizen assistance for social participation (Accompagnement-citoyen Personnalisé d'Intégration Communautaire (APIC)), a personalised intervention focusing on community integration. The APIC involves a non-professional attendant who, after 2-5 days of training, provides a stimulation session of 2-3 hours each week over a period of 6-18 months targeting significant social and leisure activities that are otherwise difficult for older adults to accomplish. Two qualitative studies demonstrated that this intervention increases accomplishment of and satisfaction with social and leisure activities among 9 adults (4 women) [START_REF] Lefebvre | Un accompagnement citoyen personnalisé en soutien à l'intégration communautaire des personnes ayant subi un traumatisme craniocérébral: vers la résilience ?[END_REF] and 11 older adults (7 women) [START_REF] Levert | Citizen Assistance for Community Integration (APIC) in older adults with traumatic brain injury: an innovative intervention supporting social participation[END_REF] with traumatic brain injury. The APIC helped them engage in constructive reflections about their lives and improve their well-being. Moreover, using mixedmethod concurrent triangulation [START_REF] Creswell | Research design: Qualitative, quantitative and mixed methods approaches[END_REF] including a pre-experimental design, an adapted version of the APIC for older adults with disabilities demonstrated feasibility [START_REF] Levasseur | Adaptation of the Personalized citizen assistance for social participation (APIC) in older adults with disabilities: a feasible intervention to foster social and leisure activities in society. Health and Social Care in the Community[END_REF] and increased mobility, accomplishment of social activities and frequency of leisure activities among 16 older adults (11 women). [START_REF] Levasseur | Personalized citizen assistance for social participation (APIC): A promising intervention Open Access for increasing mobility, accomplishment of social activities and frequency of leisure activities in older adults having disabilities[END_REF] Complementing professional healthcare services by fostering links with the community and extending services over time, the APIC helped older adults with disabilities resume, maintain, explore and experiment with significant social activities. The APIC seemed to increase their psychological and physical wellbeing, feeling of control, connectedness, self-esteem and motivation to accomplish activities. Such connectedness and accomplishment might in turn reduce loneliness and social isolation.

Although promising, the APIC needs further study. First, in previous studies, the APIC was introduced and supported by the research team, and attendants were paid. These previous studies were carried out in different conditions than the usual care settings where community organisations will be responsible for setting up the intervention. In the usual settings, the attendants will be volunteers supervised by paid coordinators and healthcare professionals. As things stand at this time, many thousands of older adults receive friendly visits from volunteers, without being explicitly empowered to use Open Access their personal and environmental resources. In addition, older adults are not appropriately stimulated to participate in the community. Moreover, as previous studies used qualitative or pre-experimental designs, studies demonstrating higher levels of evidence are needed to verify the impacts of the APIC on health, social participation and life satisfaction. This research should also be carried out with larger samples and include more men since previous studies found gender differences in social participation; for example, older women are more likely to participate in community activities than men, except for sports and physical activities. [START_REF] Naud | Social participation and environmental barriers among aging Canadians: Distribution and differences in gender, age and location[END_REF] In fact, social participation needs of women and men differ, [START_REF] Levasseur | Concordance entre besoins et interventions de participation des aînés recevant des services d'aide à domicile[END_REF][START_REF] Levasseur | Match between needs and services for participation of older adults receiving home care[END_REF][START_REF] Turcotte | Participation needs of older adults having disabilities and receiving home care: met needs mainly concern daily activities, while unmet needs mostly involve social activities[END_REF] and women have greater social connectivity than men. [START_REF] Warburton | Doing it from your heart: the role of older women as informal volunteers[END_REF] Hence, particular attention must be paid to gender in the recruitment, intervention and data analysis phases. Finally, future studies also need to consider the cost of the intervention and its effectiveness in reducing the use of healthcare services. With current public funding constraints, such a cost-effectiveness analysis, from perspectives of older adults, healthcare system and societ, constitutes critical information for decision makers. [START_REF] Drummond | Methods for the economic evaluation of health care programmes[END_REF] In summary, more studies are needed to provide community organisations with an intervention that efficiently promotes the health and social participation of community-dwelling older adults.

trial objectives and hypothesis

This study aims to evaluate: (1) the short-term and longterm effects of the APIC (respectively 0, 6 and 12 months after the end of the intervention) on older adults' physical and mental health, social participation, life satisfaction and healthcare services utilisation and (2) its cost-effectiveness. In parallel, the implementation of the APIC, including factors facilitating and impeding it, will be documented. Concerning the first two objectives, two hypotheses are formulated: (1) the APIC will prevent a decline in older women's and men's health, social participation and life satisfaction and reduce their use of healthcare services and (2) the APIC will be associated with lower costs, from perspectives of older adults, healthcare system and society, including healthcare expenditures and other costs and higher quality-adjusted life years (QALY).

MEthod And AnAlysIs study design and setting

To achieve these objectives, a pragmatic multicentre, prospective, two-armed, RCT in accordance with extended Consolidated Standards of Reporting Trials (CONSORT) statements [START_REF] Zwarenstein | CONSORT groupPragmatic Trials in Healthcare (Practihc) group. Improving the reporting of pragmatic trials: an extension of the CONSORT statement[END_REF] will be carried out. An RCT is justified to rigorously evaluate the APIC's impacts on older adults' health (primary outcome), social participation, life satisfaction and health services utilisation and its cost-effectiveness. As the intervention ultimately aims to reduce healthcare costs and improve physical, mental and social well-being, not just the absence of disease, [START_REF]Preamble to the Constitution of WHO[END_REF] health was identified as the primary outcome.

Following a call for applications, five non-profit community organisations located in three cities in Quebec, Canada, namely Montreal (3), Drummondville (1) and Quebec City (1), were selected to deliver the intervention. To be selected, these organisations had to provide direct activities and services designed to reduce social isolation and loneliness and foster health and well-being. They were currently providing direct services to thousands of older adults (median=637; range=325 to 4512). They also had to have expertise in managing projects and volunteers and the capacity to engage the community and create partnerships and be supported by a Health and Social Services Center (HSSC). In addition, each organisation has or will hire a coordinator with experience in managing projects and volunteers. These five coordinators will be specifically trained to recruit participants, enrol volunteers, assign participants to volunteers, gather informed consent, supervise baseline testing, train the volunteers and coordinate the intervention. Consistent with RCTs, 46 47 this training will underscore the importance of addressing participants' concerns, making it impossible to modify group assignment and avoiding technical terms such as 'trial' and 'randomisation'. To address participants' concerns, a guide including potential questions will be developed for coordinators. Finally, all volunteers will undergo a criminal record check.

Participants

Similar to older adults already served by community organisations, participants will have to: (1) be aged 65 years or older, (2) live at home or in seniors' residences, that is, private nursing homes for people with and without disability, (3) be restricted in at least one basic or instrumental activity of daily living (ADL) and ( 4) have a good understanding of French or English. Restriction in ADL will be identified according to a checklist of 10 activities (walking, standing, getting in and out of bed, washing, dressing, taking medication, going up or down stairs, transporting objects, shopping and house cleaning). 48 49 These activities are considered restricted if performed with difficulty or if help is required. Personal factors (pain or discomfort that restricts the accomplishment of activities as well as vision and hearing impairments, even if the person has a technical device) and home care services received will also be considered in those restrictions. Based on the coordinators' judgement and to ensure that participants understand the questionnaires, older adults presenting moderate to severe cognitive impairments will be excluded. recruitment Since older women and men have different social participation needs, various strategies will be used to recruit both genders as equally as possible. Considering the particular context of each community, strategies will involve the internet, newspapers, radio or print notices, membership and waiting lists of community organisations, community-based activities (eg, open houses), meals-on-wheels, Open Access family physicians and clinicians and outreach work. Recruitment will also target various settings, that is, health or seniors' activity centres, religious congregations, seniors' residences and low-cost housing. In the early stages of the study, regular monitoring will ensure effective strategies to reach older adults.

All older adults who potentially meet the eligibility criteria in the recruitment phase of the study, starting in October 2017, will be invited to participate consecutively, that is, as they are contacted by the organisation and until the sample size is reached (screening log). If they are interested in participating, the coordinator will meet face to face with them to discuss the project and explain that they may or may not be assigned to the experimental group. If they meet the eligibility criteria, the information and consent form will be read, discussed and signed. Once written informed consent is obtained, older adults will complete the baseline self-administered questionnaires. The coordinators will verify full completion and send the forms to the research team.

Older adults who decline to participate will, if they agree, be asked for some sociodemographic information, that is, age, gender and living situation, and reason for not participating. This information is needed to compare participants and non-participants and to document the reasons for non-participation in the intervention. randomisation After completion of the baseline questionnaires, the coordinators will reveal if the participant was randomly assigned to the experimental (APIC) or control group (figure 1) according to the Research Electronic Data Capture system. [START_REF] Harris | Research electronic data capture (REDCap)--a metadata-driven methodology and workflow process for providing translational research informatics support[END_REF] This centralised computer-generated random number sequence procedure, which cannot be modified, will stratify the randomisation according to the five community organisations and living alone versus not. The coordinator will then inform participants of their group assignments verbally and with a handout explaining the implications and time points for data measurements. Date and time of randomisation and completion of baseline questionnaires will be documented to ensure sequential enrolment.

blinding Due to the type of intervention, coordinators, volunteers and participants will not be blinded to the interventions. However, they will not be informed of the study hypotheses. As the study uses self-report questionnaires, no assessors are required. Research assistants involved in data collection (see relevant section below) and the statistician responsible for the analysis will be blinded to the intervention until completion of the study.

Intervention

Older adults in the experimental group (APIC; figure 2) will receive, over a 12-month period, weekly 3-hour personalised stimulation sessions given by an attendant, that is, a specially trained volunteer. During the sessions, the attendant will encourage the older adult to set goals, mostly concerning social and leisure activities that are important to him or her. As it is personalised and the content and format are designed for both older women and men, the intervention will foster the interest and engagement of both genders. To appropriately encourage them, the attendant must listen to the older adults and understand their needs and specific context. Doing social and leisure activities with the attendant's support will allow older adults to gradually mobilise their personal and environmental resources and become more independent and satisfied with their community integration. For example, the attendant can encourage the use of the person's planning abilities or social participation opportunities in the environment. In addition to focusing on their specific needs and interests according to their life context, this intervention is intended to empower older adults and build on their strengths and skills.

Attendants' training

Attendants will participate in a face-to-face 1 day 6 hour training session addressing the following topics: (1) Open Access core components underlying the intervention, (2) roles, mentoring and tools, (3) process to help older adults set goals for accomplishing social and leisure activities and empowerment, (4) knowledge about people with disabilities and (5) knowledge about social and leisure activities available in the community. Each attendant will also be given an attendant's guide including information on these topics.

This training will be supplemented with online video presentations focusing on knowledge about specific disabilities, for example, mild cognitive, visual or mobility impairments. These narrated PowerPoint presentations will also remind the attendant how to help older adults set goals for accomplishing social and leisure activities.

To evaluate implementation fidelity and monitor APIC attendance and for their own supervision, each week attendants will record in a semistructured diary template the date and length of visits and, if known, reasons for missing a visit. In this diary, attendants will also record the content of the visit, that is, reflections on life projects based on interests and needs, activities done or planned, as well as facilitating and impeding factors. Attendants will be encouraged to record their feelings and concerns, which will enable the coordinator to support them in complex situations. The diary will also allow coordinators to monitor adherence to the intervention and provide further assistance and training to attendants when required. Each month, attendants will also participate in a support and training meeting with a healthcare professional (occupational therapist, social worker or specialised educator) and the coordinator. These meetings will involve sharing successes, addressing difficulties and training to prepare the end of the intervention. If needed, coordinators will also organise individual contacts or meetings to help attendants resolve difficulties.

Control group

According to their specific needs and situation, the control group will receive the usual publicly funded healthcare services available to all residents of Quebec (eg, outpatient contacts with physicians and ambulatory emergency department visits, rehabilitation and inpatient stays). At the end of the study, participants in the control group will be offered the APIC. outcomes Five self-report questionnaires will be used at baseline and, except for the sociodemographic variables, after the intervention is completed (12, 18 and 24 months later) to evaluate the short-term and long-term effects of the intervention on primary (health) and secondary (social participation, life satisfaction and healthcare services utilisation) outcomes and to describe the participants (table 1).

Primary outcomes

Physical and mental health will be estimated with version 2 of the 36-item Short-Form Health Survey (SF-36) [START_REF] Ware | How to Score Version 2 of the SF-36(r) Health Survey[END_REF] which includes eight domains. Using algorithms, physical and mental components are calculated from the eight scales. [START_REF] Ware | SF-36 Physical & Mental Health Summary Scales: A Manual for Users of Version 1[END_REF] Scores range from 0 to 100, with a higher score indicating better health. [START_REF] Ware | SF-36 health survey update[END_REF] Widely used in studies, [START_REF] Mchorney | The MOS 36-item Short-Form Health Survey (SF-36): III. Tests of data quality, scaling assumptions, and reliability across diverse patient groups[END_REF] the SF-36 has norms (mean=50; SD=10) and good psychometric properties, including with older adults. [START_REF] Hayes | The SF-36 health survey questionnaire: is it suitable for use with older adults?[END_REF] For example, Gandek et al [START_REF] Gandek | Psychometric evaluation of the SF-36 health survey in Medicare managed care[END_REF] Open Access domains, and 0.94 and 0.89 for the physical and mental components, respectively). In addition, this questionnaire presents good test-retest reliability, even for testing after 6 months (correlation coefficients from 0.60 to 0.90, except for bodily pain (0.43)). [START_REF] Ware | SF-36 health survey update[END_REF] Finally, the SF-36 is sensitive to change, [START_REF] Gatchel | The association of the SF-36 health status survey with 1-year socioeconomic outcomes in a chronically disabled spinal disorder population[END_REF] with a difference of 5 points in scale scores being clinically significant, as suggested by Ware et al. [START_REF] Ware | SF36 Health Survey: Manual and Interpretation Guide[END_REF] secondary outcomes Use of healthcare services will be recorded on a standardised questionnaire adapted from previous studies. [START_REF] Hay | Cost-effectiveness of preventive occupational therapy for independent-living older adults[END_REF] This questionnaire includes 14 questions covering visits to medical and health professionals in hospital, at the office or at home, hospitalisation or inpatient rehabilitation, outpatient tests, home care and caregiver costs. For each service used, details regarding the frequency, time period and cost will be collected. Social participation will be measured with the Social Participation Scale, [START_REF] Richard | Neighborhood resources and social participation among older adults: results from the VoisiNuage study[END_REF] a questionnaire that considers the frequency of accomplishment in 1 month of 10 social and community activities. Answers are transformed into a number of days, with the total score representing the sum of days of activities in 1 month. This instrument has good internal consistency (Cronbach's α from 0.85 to 0.91) with older adults living in an urban setting. [START_REF] Richard | Staying connected: neighbourhood correlates of social participation among older adults living in an urban environment in Montreal, Quebec[END_REF] Developed specifically for older adults, the Life Satisfaction Index-Z (LSI-Z) [START_REF] Wood | An analysis of a short self-report measure of life satisfaction: correlation with rater judgments[END_REF] includes 13 items that explore five components of life satisfaction. Using a three-point scoring system, the score ranges from 0 to 26, with a higher score indicating greater satisfaction. [START_REF] Wood | An analysis of a short self-report measure of life satisfaction: correlation with rater judgments[END_REF] The LSI-Z presents moderate criterion validity with a longer version of the tool (correlation coefficient=0.57) and good internal consistency (Cronbach's α of 0.79). [START_REF] Wood | An analysis of a short self-report measure of life satisfaction: correlation with rater judgments[END_REF] Sociodemographic variables will include gender, education, marital status, place of birth and annual family income.

Economic evaluation

The SF-36 scores will be converted to the Short-Form Six-Dimension (SF-6D) utility scores for the QALY calculation, which will identify the mean health benefits of the APIC for participants. The economic evaluation will include healthcare system costs for health services received and other indirect costs for travelling and time spent during programme and medical visits, as well as productivity losses and caregiver costs. For example, for each participant, caregiver costs such as paid and unpaid inhome support for shopping, laundry, housekeeping or cooking or assistance in making doctor appointments [START_REF] Hay | Cost-effectiveness of preventive occupational therapy for independent-living older adults[END_REF] will be calculated using predetermined fees. 63 64 These costs will be calculated from older adults, healthcare system and societal perspectives. Intervention costs of the experimental group will be calculated based on the total funding attributed to organisations and will consider contacts and time spent with participants, preparation and travel time/fee for coordinators and volunteers. 28 59 No programme-related costs will be attributed to the control group.

Implementation

A process evaluation will be used to assess fidelity and quality of implementation, clarify causal mechanisms and identify contextual factors associated with variations in outcomes. [START_REF] Hogue | Treatment adherence, competence, and outcome in individual and family therapy for adolescent behavior problems[END_REF][START_REF] Craig | Developing and evaluating complex interventions: the new Medical Research Council guidance[END_REF][START_REF] Moore | Process evaluation of complex interventions: Medical Research Council guidance[END_REF] In addition to APIC attendance rates recorded in the attendant's diary, a fidelity questionnaire will be completed every 2 months by each coordinator. This questionnaire will document adherence to the intervention, that is, extent to which coordinators' actions are carried out as planned 65 68 and essential components of the APIC are implemented. The fidelity questionnaire includes 24 questions answered on a 4-point Likert scale. This questionnaire has been demonstrated to be a feasible, reliable and valid measure of fidelity implementation. [START_REF] Breitenstein | Measuring implementation fidelity in a community-based parenting intervention[END_REF] Factors facilitating or impeding the implementation will also be explored with coordinators and the primary research assistant using semidirected interviews Open Access at 6 and 12 months after the beginning of the implementation and during each bimonthly meeting. This exploration will consider the context of the different community settings, including opportunities and constraints, and document differences between planned and delivered interventions.

sample size

Each community organisation will recruit 75 older adults for a total of 376 participants. Based on similar RCTs 28 70 and anticipating an attrition rate of 20% (Trial Consort flow diagram; figure 3), a sample size of 188 per group (150 per group at the end of the study) will detect an effect size of 0.325 in the primary outcome between groups with a power of 80% and a two-sided α error of 5%. [START_REF] Machin | Sample size tables for clinical studies. 3rd edn[END_REF] Although, due to limited budget and feasibility considerations, it was not possible to consider gender in the sample size calculation, gender interaction will be explored (see below). An effect size of this magnitude is consistent with studies of similar social interventions. 28 70 As the SD of differences in change scores can be expected to vary between 14 and 20 points across SF-36 subscales, 70 72 this effect size corresponds to group differences of 4.6-6.5 points, which is considered a clinically important difference. Feasibility in reaching this sample size is based on previous APIC studies that recruited 71.4% and 59.3% of older adults, respectively, in a research setting [START_REF] Levasseur | Personalized citizen assistance for social participation (APIC): A promising intervention Open Access for increasing mobility, accomplishment of social activities and frequency of leisure activities in older adults having disabilities[END_REF] and in one rural community organisation. 73 As they might assist more than one older adult, it is anticipated that 150-175 attendants (30-35 per organisation) will be required.

data collection

As mentioned, coordinators will hold initial face-to-face meetings lasting approximately 45 min with all participants that will include supervising completion of the baseline questionnaires. Ideally, the APIC will begin within 1 month and as soon as possible after the baseline measures. This strategy aims to avoid the loss of participants (death and withdrawal of consent) between randomisation and the beginning of the intervention.

Following the intervention, 12 (T1), 18 (T2) and 24 (T3) months after baseline, participants will complete the same outcome questionnaires (table 1) that will be mailed to them with a stamped return envelope. If the questionnaires returned have missing or incongruent data, the research assistant will call the older adults to complete or verify the answers. If the questionnaires are not received within 2 weeks, the research assistant will call the older adults to offer them extra time or the option to complete the questionnaires over the phone. If the questionnaires are still not received within a further 2 weeks, the research assistant will call the older adults again to offer them the option to complete the questionnaires over the phone. These strategies reduce missing data or undue data collection delays. Moreover, to recognise their time and involvement, and encourage retention in the study, participants will receive $10 financial compensation at each measurement time.

Finally, to record the use of healthcare services, telephone interviews lasting approximately 15 min will be conducted by trained research assistants with all participants every 2 months throughout the 2-year period of the study. To lessen recall bias, participants will be encouraged to use a calendar to record their use of healthcare services and be asked to use this calendar during the interviews. Assisted self-report of health services use by older adults through phone calls every 2 months is reliable. [START_REF] Dubois | Assisted self-report of healthservices use showed excellent reliability in a longitudinal study of older adults[END_REF] Open Access data analysis Descriptive statistics will be used to describe the participants and document implementation fidelity, including attendance rates as well as adherence to the protocol, that is, the difference between planned and delivered interventions. Since outcomes will be measured four times (baseline, 12, 18 and 24 months later), a multilevel model for change (growth model) will be used to evaluate and compare the effectiveness of the interventions by comparing both the primary (health) and secondary (social participation, life satisfaction and healthcare services utilisation) outcomes at different timepoints and between groups while adjusting for the two stratification factors (community organisation and living alone vs not). [START_REF] Kahan | Reporting and analysis of trials using stratified randomisation in leading medical journals: review and reanalysis[END_REF] All analyses will be based on the intention-totreat principle. and growth modelling will handle missing outcomes by using all available data from each older adult, even those who do not participate in all measurements. If the number and characteristics of losses to follow-up are generally unbalanced between the groups, sensitivity analyses will be conducted to see how consistent the results are across different methods to handle missing data.

The economic evaluation from the societal perspective will be based on the incremental cost-effectiveness ratio, which will be calculated as the average total difference in costs, divided by the difference in QALYs between the experimental and control groups. [START_REF] Little | Statistical analysis with missing data[END_REF] For the incremental 2-year total cost estimates, general linear models (GLM) with the best link function and family distribution [START_REF] Hoch | Using the net benefit regression framework to construct cost-effectiveness acceptability curves: an example using data from a trial of external loop recorders versus Holter monitoring for ambulatory monitoring of "community acquired" syncope[END_REF] will be used. The 2-year QALYs will be calculated with the utility scores obtained from the SF-6D [QALY=life year (duration)*utility (morbidity) in that health state]. [START_REF] Drummond | Methods for the economic evaluation of health care programmes[END_REF] GLM will also be carried out to test for differences (ie, β estimates) in QALYs between the two study arms while controlling for sociodemographic variables and assessing impacts of gender on outcomes by testing the interaction terms [gender*study arm, gender*compliance rates]. These analyses will be carried out at the end of data collection, in intention-to-treat and considering gender. To ensure quality and limit bias, a statistician will manage and analyse the data. CIs for the cost-effectiveness ratio will also be calculated by using the bootstrap method with 1000 replications. To inform decision makers on best value for money invested, cost-effectiveness acceptability curves with varying amounts of willingness to pay (λ) will be calculated as described by Hoch and colleagues. [START_REF] Hoch | Using the net benefit regression framework to construct cost-effectiveness acceptability curves: an example using data from a trial of external loop recorders versus Holter monitoring for ambulatory monitoring of "community acquired" syncope[END_REF] All the quantitative analyses will be conducted by a statistician blind to the group allocation using SAS V.9.4 and in accordance with CONSORT standards and overseen by the methodological research committee.

To document facilitating and impeding factors and evaluate differences between planned and delivered interventions, interview transcripts and attendants' diaries will be analysed with thematic content analysis and mixed extraction grids [START_REF] Miles | Qualitative data analysis: a methods sourcebook[END_REF] using NVivo V.10 (QRS International, Doncaster, Victoria, Australia). The content of interview transcripts and diaries will be divided into units of sense, organised and reformulated in the disciplinary language and synthesised into themes. These themes will represent facilitating or impeding factors as well as essential components of the implementation. Interview transcripts and attendants' diaries will be exhaustively analysed by one research assistant to reach consensus for one third of the data cocoded by researchers. Correlation coefficients will also explore associations between attendance rates and fidelity score, on the one hand, and outcomes, on the other hand, at 12 months. Finally, facilitators, barriers and essential conditions for successful implementation, along with the effects of the intervention on older adults' health, social participation and life satisfaction, will also be examined according to gender; that is, gender effects will be considered in the qualitative and quantitative analyses described above.

trIAl MAnAgEMEnt And MonItorIng An interdisciplinary committee involving six researchers, two clinicians, two healthcare service administrators, the five administrators of the participating community organisations, two community citizens (patient partners and family members) as well as one research assistant will ensure the study progresses as planned. The committee will hold four recorded statutory meetings each year, contributing to implementing the APIC, participating in training and supporting coordinators and organisations. Biweekly phone contacts with the coordinators and bimonthly meetings will involve supervision of strategies and actions of community organisations to ensure recruitment of participants and proper delivery of the intervention. As recruitment of both older adults and volunteers is among the anticipated challenges, a communication plan including various and gradual strategies is provided and will be adapted to the needs of each organisation. If required, a sixth organisation will be involved to reach the sample size. To avoid contamination, attendants will volunteer only with older adults in the experimental group. Coordinators, attendants and participants in the experimental group will be asked not to share information about the APIC with other volunteers or older adults. Finally, biannual visits to the study sites will be carried out to monitor progress in accordance with the planned intervention. These visits will also enable one research assistant and the principal investigator to verify that participants' rights are protected and that data collected are accurate and complete.

EthICs And dIssEMInAtIon

In accordance with the Declaration of Helsinki, 79 every participant will give written, free and informed consent.

Potential harms for participants include the possibility of feeling tired, uncomfortable or emotional during personalised sessions with attendants. These situations will be reported in the diary completed each week by the attendants, allowing the coordinator to react quickly if needed. Attendants are sensitised and advised to inform Open Access the coordinator who, with the support of the HSSC, has the expertise to handle this type of situation. If needed and desired, the older adult will be referred to a health professional.

At the end of the study, if the study demonstrates positive effects of the APIC on older adults' health, social participation, life satisfaction or healthcare services utilisation, control group participants will be offered the APIC. Following a dissemination plan, findings of this multicentre study will be published in peer-reviewed journals in the field of healthcare outcomes, community integration or health economics. Conferences targeting various audiences, for example, healthcare professionals and community organisations at the local, national and international level, are also planned. Finally, an APIC implementation guide will be disseminated. dIsCussIon This large scale community-based study will evaluate: (1) the short-term and long-term effects of the APIC on older adults' health, social participation, life satisfaction and healthcare services utilisation and (2) its cost-effectiveness. The underlying trial proposes to compare, over a 2-year period, a novel health-promoting intervention involving weekly 3-hour personalised stimulation sessions encouraging empowerment, gradual mobilisation of personal and environmental resources and community integration, to the usual publicly funded universal healthcare services available to all Quebecers. Previously introduced and supported by the research team, with paid attendants and a limited number of older adults, the APIC in the present study will be carried out with a larger sample and be delivered by community organisations in 'real world contexts' and in partnership with HSSCs. Like previous RCTs on Lifestyle Redesign, 28 70 72 the current study will generate new knowledge on the short-term and long-term effects of the APIC on health outcomes and its cost-effectiveness, including comparison of healthcare costs between the experimental and control groups.

Demonstrated as being feasible [START_REF] Levasseur | Adaptation of the Personalized citizen assistance for social participation (APIC) in older adults with disabilities: a feasible intervention to foster social and leisure activities in society. Health and Social Care in the Community[END_REF] and having positive effects, [START_REF] Levasseur | Personalized citizen assistance for social participation (APIC): A promising intervention Open Access for increasing mobility, accomplishment of social activities and frequency of leisure activities in older adults having disabilities[END_REF] the APIC has a high potential to improve health, social participation and life satisfaction among older adults, reduce the use of healthcare services and improve the cost-effectiveness of current practices. As the impact on health and use of healthcare services of social interventions targeting older adults remains unclear, [START_REF] Coll-Planas | Social capital interventions targeting older people and their impact on health: a systematic review[END_REF] results from this effectiveness and cost-effectiveness study, using the gold standard method to evaluate the effects of an intervention, will provide rich data about economic aspects according to the implementation of the APIC in different sociocultural contexts. [START_REF] Craig | Developing and evaluating complex interventions: the new Medical Research Council guidance[END_REF] With current public funding constraints, such a cost-effectiveness analysis, from perspectives of older adults, healthcare system and society, constitutes critical information for decision makers. [START_REF] Drummond | Methods for the economic evaluation of health care programmes[END_REF] As the APIC is a complex social intervention [START_REF] Craig | Developing and evaluating complex interventions: the new Medical Research Council guidance[END_REF] with outcomes influenced by the intervention itself as well as the participants' characteristics, results concerning its implementation, that is, how and in which context the intervention is provided by attendants and what the response from older adults is, will generate important new knowledge.

Findings of this pragmatic trial evaluating both the shortterm and long-term effects of the APIC and its cost-effectiveness are expected to enrich current practices [START_REF] Clapperton | La prévention pratico-pratique[END_REF] and have great potential for concrete and positive individual and societal benefits. An intersectoral team, including national and international experts, will ensure the high quality of this pragmatic multicentre, prospective, two-armed RCT. Among possible limitations and like other trials involving social interventions, blinding to group allocation will not be possible [START_REF] Foster | Methodological issues in pragmatic trials of complex interventions in primary care[END_REF] for older adults, coordinators and attendants. To minimise the probability of ascertainment bias, trial management and monitoring will involve supervisory mechanisms including biweekly phone contacts and bimonthly meetings with coordinators. These mechanisms will also target possible contamination bias recognised in the discussions and reduced by identifying strategies. One of these strategies is to ensure that attendants volunteer only with older adults in the experimental group. Coordinators, attendants and participants in the experimental group will also be asked not to share information about the APIC with other volunteers or older adults. As the APIC takes place in the participants' homes or community according to the older adults' needs and interests, the probability of contamination is reduced. For feasibility and pragmatic reasons, the presence of cognitive impairment in the older participants will be based on the coordinators' judgement in the initial face-to-face meeting rather than with a standardised tool, a possible limitation of this study in regard to respecting exclusion criteria and generalisation of results. Although older adults with cognitive impairment may benefit from the intervention and coordinators will all have significant experience with older adults and will be rigorously selected and closely supervised by the research team, the cognitive capacities of the older participants must be such that they can understand and answer the questionnaires properly. Finally, consistent with similar RCTs [START_REF] Clark | Occupational therapy for independent-living older adults. A randomized controlled trial[END_REF] showing no difference between a social activity control group and a no-treatment control group with multiple long-term follow-up measures, and to reduce costs and logistical challenges, the present study includes only one control group.

Figure 1

 1 Figure 1 Study design. R, randomisation; X, assessment, TX, treatment (APIC). APIC, Accompagnement-citoyen Personnalisé d'Intégration Communautaire.

  demonstrated good internal consistency (Cronbach's α from 0.83 to 0.93 for the eight

Figure 2

 2 Figure 2 Personalised citizen assistance for social participation (APIC) logic model.

Figure 3

 3 Figure 3 Trial Consort flow diagram. APIC, Accompagnement-citoyen Personnalisé d'Intégration Communautaire.

Table 1

 1 Outcomes, measures and time points

			T 1 (12 months)
	Outcome (measures)	T 0 (baseline)	postintervention
	Life satisfaction (Life Satisfaction Index-Z)	√	√	√	√
	Sociodemographic variables (home questionnaire) √

*Primary outcome.

Acknowledgements

The authors wish to thank Dr Jacques Lacroix, Janusz Kaczorowski and Andrée Sévigny for their questions and comments on a previous version of this protocol.

Contributors ML prepared the first draft of this manuscript with the assistance of JL-B. All coauthors (M-FD, JF, H-MV, AT, M-JL, CG, HL, VB and CE) revised the manuscript and approved the final version.

Funding This work was supported by a Foundation Grant (#148466) from the Canadian Institutes of Health Research (CIHR) and its publication by the Social Inequalities and Equity Strategic Grouping of the Quebec Population Health Research Network. ML is a Junior 1 Fonds de la recherche en santé du Québec (FRSQ) Researcher (salary award #26815, 2013-2017) and a CIHR New Investigator (salary award #360880, 2017-2022).

Competing interests None declared.

Patient consent Not required.

Ethics approval This study has been approved by the Research Ethics Committee of the CIUSSS de l'Estrie-CHUS (MP-31-2018-2424). The Committee will be notified of all substantial modifications to the protocol.

Provenance and peer review Not commissioned; externally peer reviewed. data sharing statement Data will be available upon request to corresponding author.