Aesthetic physicians and surgeons should consider differences in anthropometric and anatomical characteristics between Asians and Caucasians in performing facial rejuvenation procedures using absorbable threadlifts in Koreans.This paper was prepared to propose empirical treatment protocols for Korean aesthetic physicians and surgeons.A panel of 5 Korean experts on the aesthetic uses of an absorbable polydioxanone (PDO) monofilament threadlift , thus termed as “the Mint Consensus Group,” was convened to recommend practical guidelines for empirical treatment with the Mint Lift.To summarize, our recommendations are as follows: First, the entry and exit points should be determined considering the anatomical characteristics of the face (level of evidence III). Second, treatment procedures may vary depending on indications (level of evidence III).Here, the authors propose empirical treatment protocols for facial rejuvenation using a novel absorbable PDO monofilament threadlift in Koreans. But more evidence-based efforts should be made to update the current treatment protocols. Their demerits, such as increased facial volume, unnatural contour, and visible shift of the gravity center to the lower one-third of the face, have remained problematic.4-6 Moreover, despite the efficacy of ablative or non-ablative resurfacing techniques in improving the skin surface, they have a lack of sufficient lifting of the underlying ptotic tissues.8To date, surgical face-lifting has been frequently performed to excise the redundant skin for facial rejuvenation.9 Therefore, a threadlifting has been considered an alternative to conventional types of surgical face-lifting.10Patients with sagging and facial flaccidity are recommended to receive a threadlifting whose merits include decreases in time to recovery and incisions.11 first reported treatment outcomes of threadlifting using polypropylene barbed anti-ptosis sutures. Since then, diverse types of threadlifting procedures have been developed.12 Particularly in Asia, polydioxanone (PDO) threadlifts have recently become commercially available and then used for minimally invasive facial rejuvenation procedures.13-16In 2002, Sulamanidze et al17-19 Diverse types of the Mint Lift products, such as the Mint Lift 43, 17, Fine and Easy, are available to meet the needs of aesthetic physicians and surgeons as well as patients.19Classified as a class IV medical device, the Mint Lift  is a violet-colored, absorbable PDO monofilament threadlift with a wire length of 43 cm and a US Pharmacopeia (USP) size of 0. Its properties include a transparency seen on postoperative month 1, bidirectional helical barbs providing an initial strong skin anchorage without an attachment of the yarn to the needle. Moreover, it is inserted initially using a curved needle (5/8) and then later using an 18-G blunt cannula, for which the disposable, external trocar is concomitantly used.Given the above background, we conducted this study to propose treatment protocols for facial rejuvenation using the Mint Lift products in Koreans.A panel of 5 Korean experts on the aesthetic uses of an absorbable PDO monofilament threadlift (Mint Lift), thus termed as the “Mint Consensus Group,” was organized on November 7, 2018. The “Mint Consensus Group” is composed of 5 aesthetic physicians and surgeons, whose specialty areas include facial and body contouring, urology, facial plastic surgery, otorhinolaryngology, and obstetrics and gynecology. All of them were men with a mean age of 48.20 ± 4.96 years old. The number of cases for which they had performed facial rejuvenation procedures by the end of 2018 ranged between 50 and 4000.In April 9, 2019, the Mint Consensus Meeting was held to recommend empirical treatment protocols for facial rejuvenation using the Mint Lift.To propose the current treatment protocols, we performed a review of the previous published studies about facial rejuvenation using a threadlift. Moreover, a formal discussion was convened to reach a consensus on the best clinical practices for facial rejuvenation using the Mint Lift between the members of the “Mint Consensus Group.” Then, their opinions were compiled by collecting personal experiences and opinions through discussions. The current study was conducted during November 7, 2018, and April 9, 2019.The current study was conducted in compliance with the relevant ethics guidelines; all procedures described herein were performed in accordance with the 1964 Declaration of Helsinki and its later amendments or comparable ethical standards. The current study was approved by the Internal Institutional Review Board of the Korea National Institute of Bioethics Policy (2020-03-637-172). But a written informed consent was waived due to the retrospective nature of the current study.17-19For facial rejuvenation procedures using the Mint Lift, the entry and exit points are determined considering the anatomic characteristics of the face, as previously described.The Mint Lift Fine can be inserted in any entry points determined on the face because of its user-friendly interface that is irrespective of vectors and a lack of possibility of its causing dimpling at the entry points . But theIn patients with a poorly developed zygomatic arch, the midface lifting is performed using the vector perpendicular to the nasolabial folds. That is, such vector is horizontal to that used for temporal anchoring. It, therefore, becomes possible to perform the procedure by attaching the threadlift to the periphery of the eye without lifting the eye corner. This is advantageous in preventing the formation of the lifted eye corner which most of the Koreans dislike and the rigid boundary formed by the zygomatic ligament.The entry point is determined below the temple, and the exit one is located within the lateral canthus but not displaced to the zygomatic cutaneous ligament. Due to an abundant presence of the fibrous tissue in the lower face, it is highly movable. This may cause dimpling when the cog is stuck .The depth of the insertion of the threadlift deserves special attention because of a thin layer of the subcutaneous fat in patients for whom the exit point is located near the maxilla. A slight deeper insertion of the threadlift may cause it to enter the premaxillary space, which may produce poor treatment outcomes, such as a thickening of the premaxillary space.In patients with a well-developed zygomatic arch, the entry point cannot be determined on the temple. This is because treatment effects cannot be achieved involving the inner superficial muscular aponeurotic system (SMAS) in such patients. It is, therefore, recommended that the entry point be determined around the inner zygomatic arch and the exit one be located above the nasolabial folds . MoreoveIn patients with jowl fat, Marionette’s line and those who are in need of lower facial rejuvenation, the Mint Lift Fine is inserted in the entry site around the zygomatic arch before the temporomandibular joint (TMJ) through a lateral ear approach. Then, the exit point is determined on the jowl fat and the knot is tied (Video 1). This is such a simple, efficient technique that can be performed by even inexperienced aesthetic physicians and surgeons, whose advantages include the following: First, a postoperative recovery period is relatively shorter. Second, even the midcheek hollowness can be effectively corrected by lifting the sagging fat to the midface with the use of a bidirectional cog threadlift. This may eventually contribute to forming a more natural egg-shaped face. Third, the entry site is less affected by the jaw movement because it is located proximal to the TMJ, which leads to a decrease in the degree of mechanical stimulation of barb to the tissue, arising from the jaw movement, followed by stabilization of the fixation of threadlift at the entry point. Fourth, because the entry point is determined above the zygomatic ligament, the threadlift can be fixed more stably through the application of the traction force from the zygomatic ligament. A knot is tied concomitantly with the procedure. This may sustain treatment effects by increasing the degree of tissue lifting. Fifth, from anatomical perspectives, the entry site is located remote from the pathway of the superficial temporal artery and then determined on the region where that of the temporal branch of the facial nerve is deeply present. Therefore, vital vessels and nerves are left intact. Sixth, patients can return to their daily lives even immediately after the procedure because of a relatively shorter recovery period.To determine the vector from the entry point to the exit one, the former is located on the zygomatic arch and the latter is determined in the jowl. If necessary, the entry site may be determined below the ear or on the tragus. Considering that the high SMAS face-lift technique is preferred for surgical lifting procedure, however, we assume that the entry site should be determined above the ear .For the procedure using the Mint Lift Easy, the entry point is determined in the platysma-auricular ligament below the ear and the exit one is located in the jowl and lateral to the ear. Both the vertical and horizontal vectors are used to smoothly lift the tissue to the midline of the target site.For the rejuvenation of jaw, causes of age-related sagging should be checked. These include adipogenesis, sagging of the muscle, and development of salivary glands. In patients with sagging of the muscle, the double-jaw procedure has been the most effective treatment modality. A liposuction has been frequently performed for the rejuvenation of jaw, although the threadlifting is recommended as a more effective treatment modality in patients with severe sagging of the muscle. An accurate differential diagnosis should be made before the recommendation of the optimal treatment modalities.A hammock procedure is performed using a fixation type bidirectional cog thread, for which the entry site is determined in the central part of the jaw and the exit point is bilaterally located in the outside of the jaw. It is differentiated from other procedures in that it is performed to fix both sides of the jaw and to pull its central part, without simply pulling the tissue, for the purposes of exhibiting hammock-like effects (Video 2).In conventional types of a fixation type, bidirectional cog thread is used to tract the tissue in the central part of the jaw, thus causing its bulging. But a hammock procedure is characterized by the traction of sagging tissue without causing its bulging. Therefore, the entry point located in the central part of the jaw has an effect in pulling the sagging tissue as it also serves the exit one .As described above, a hammock procedure is an effective modality in patients with sagging of the muscle accompanied by a poorly developed fat tissue. Its treatment goal is to lift the platysma layer. In patients with slightly sagging of the fat, however, the superficial insertion of the threadlift in the entry point may effect in lifting the fat layer. Moreover, patients with an excessive amount of fat may also be treated with monofilament threadlift.Patients are commonly placed in a cervical extension position, which is disadvantageous in that there is an increase in the degree of tension applied to the SMAS. This also leads to an increase in the degree of tension applied to the platysma muscle, which may lower the degree of effects in lifting it despite the traction of it. It is, therefore, recommended that patients be placed in such a position that the cervical spine is slightly flexed so that there may be a decrease in the degree of tension applied to the platysma muscle.A staple-shaped procedure is performed involving the jowl; it is a useful modality with the Mint Lift Easy in improving the mandibular contour. At the outpatient clinic, we commonly encounter patients without sagging of fat whose major concerns are improvement of the mandibular contour rather than that of the mandibular ptosis. These patients may be indicated in a staple-shaped procedure; the entry point is located in the platysma-auricular ligament below the ear, and the exit one is determined in the jowl on one side and the supraplatysmal fat . Illustr21 Despite the availability of both absorbable and nonabsorbable threadlifts, the latter is disadvantageous in that it is permanently left in the tissue and then palpated on the skin. Patients receiving nonabsorbable threadlifts may be vulnerable to complications such as skin dimpling or suture extrusion. Therefore, the use of absorbable threadlifts has been preferred.23The advantages of minimally invasive facial rejuvenation techniques include shorter operation time, office-based treatment procedures, and fewer perioperative complications.24 Of the absorbable PDO threadlifts, Mint Lift has been reported to be an effective, safe one.24-26 From empirical perspectives, treatment effects are sustained during a maximum period of approximately 8 months, for which further long-term follow-up studies are mandatory. Moreover, facial rejuvenation procedures using the Mint Lift require no overcorrection.With the emergence of PDO threads, great advances have been made in facial rejuvenation techniques using absorbable threadlifts.To summarize, our recommendations are as follows:17-19(1 ) The entry and exit points should be determined considering the anatomical characteristics of the face (level of evidence III).17-19 But this deserves further evidence-based studies.(2) Treatment procedures may vary depending on indications (level of evidence III).Here, we propose treatment protocols for facial rejuvenation using a novel absorbable PDO monofilament threadlift in Koreans. But more evidence-based efforts should be made to update the current treatment protocols.


A new trend in recent years for hydrographic measurement in water bodies is the use of unmanned surface vehicles (USVs). In the process of navigation by USVs, it is particularly important to control position precisely on the measuring profile. Precise navigation with respect to the measuring profile avoids registration of redundant data and thus saves time and survey costs. This article addresses the issue of precise navigation of the hydrographic unit on the measuring profile with the use of a nonlinear adaptive autopilot. The results of experiments concerning hydrographic measurements performed in real conditions using an USV are discussed. The importance of hydrographic measurement in recent years has been growing constantly due to the increasing use of water transport, including movements in restricted areas. A particular challenge is shallow-water measurements near land or navigational obstacles where the use of larger hydrographic units is impracticable or not justified economically. An important aspect in this respect is the desire to shift loads from roads and motorways to waterways, which, by definition, are safer and transport is more ecologically friendly and economical.The process of conducting hydrographic measurements in land-restricted waterways requires precise acquisition of the measurement profile, and a limit to the acquisition of redundant data on the measurement strip tabs in the case of multi-beam echosounder (MBES) measurements and excessive gaps between measurement profiles in the case of single-beam sonar measurements. The International Hydrographic Organization (IHO) does not define the accuracy of maintaining the measuring unit on the profile, but only determines the percentage of searching the bottom of the reservoir and the accuracy of determining the position of the measuring unit. For instance, in the case of the most restrictive special category, 100% coverage and an accuracy of 2 m with respect to determination of position with a 95% confidence level is required [Traditionally, for manned hydrographic units, the helmsman follows the position of the unit on the profile on the monitor screen of the measurement system, adjusting the parameters of the unit’s movement to the current weather conditions. Many measurement systems used throughout the world provide the helmsman with an indicator which shows the current distance from the planned measurement profile. Continuous tracking of the position of the measuring unit on the profile requires a high degree of concentration and an appropriate response from the helmsman; this is a tedious and challenging task. It requires a relatively frequent change of the watch in the case of the helmsman controlling the hydrographic unit.A disadvantage of manual control is also the quite low accuracy of maintaining the measuring unit on the profile and a moment of inattention or distraction may result in deviation from the measuring profile thus requiring repetition of registration on the incorrectly registered profile. For this reason, significant amounts of redundant data are recorded, which hamper the processing of the measurement data. The issue of achieving precise control of the measurement profile on a hydrographic unit can be solved by using an unmanned surface vehicle (USV) with an adaptive autopilot which realizes precise control of both course and speed.Generally, unmanned mobile platforms, including surface, aerial, and ground vehicles have been increasingly employed for numerous operations. Currently, the unmanned platforms are widely used around the world, giving rise to many new research opportunities. In this context, various control schemes have been also developed to perform predefined tasks. Unmanned surface vessels suffer from many uncertainties and unknown external disturbances like winds, waves, currents, etc., which inevitably lead to a very challenging task  like accThis paper considers the problems of precise control of the measurement profile on a hydrographic unit using a nonlinear adaptive autopilot originally designed for unmanned aerial vehicles. The results of experiments carried out under real conditions are presented.Precise tracking of the trajectory during maneuvering is very important, especially for an autonomous multi-purpose water platform ,23 engagThe evaluated track following method, termed guidance logic, was designed originally for aerial applications  and unmaAn outline of the steps and the computer programing methods used for trajectory tracking is given in This algorithm requires a frequency of 50 Hz (method name: update), meaning that the update method is used 50 times per second. The method is activated only in automatic mode, meaning that only the automatic modes Auto, Guided, Return to Dock (RTD), and Smart RTD use this method. The automatic modes make use of all navigation sensors, and valid sensors readings are compulsory for automatic mode activation. Any missing sensors’ data are unable to activate this function. Moreover, the Auto mode requires a programmed route (route plan), the RTD mode requires a dock (home) position and a saved travelled route to perform smart RTD, and the Guided mode requires a desired point location. All data are provided in the form of geographical waypoints (WPs).Steering WP—the basic route plan and vehicle destination. The method provides the location that the vehicle should achieve (destination).NLG controller—the method where the navigation process is implemented. The method, based on destination and vehicle origin, calculates the lateral acceleration.Steering LA—the method, based on the PID  controller, calculates the steering output.Set Steering—the method converts the steering output to the appropriate navigation controller output signal. The output signal (PWM: Pulse-Width Modulation) is the electrical signal interpreted by the electric motor’s controller and the rudder’s linear actuator controller.The update method uses, in order, the following methods:All the methods enumerated above participate in trajectory tracking and have been tuned separately during the platform development and validation process.The guidance logic  selects  vehicle . Knowinglsewhere , the metThe original Equations (1) and (2) were modified  for USV The cross-track error (XTE), corresponding to The dynamics of Equation (6) indicate that changing the values of The parameter tuning requires some user experience regarding the USV’s parameters and the response observations during the trials. As a general rule for tuning, the following instructions are given. The uto mode . This paSignificant changes made to the original Equation (1) enable the length The L1 Control Gain was changed from a fixed value of 2 (Equation (1)) to be calculated based on the The L1 method calculates the lateral acceleration to be executed by the unit. The  methods . The SteThe steering system specification for the unit  is basedSkid-Steering is a type of vehicle steering where rotation (yaw) is obtained by a difference in the speeds of the left and right propellers (wheel) and is typical for vehicles with non-orientable propellers (wheels). Electric motors installed on the platform and situated in the right hull are turned using a linear actuator, therefore, maneuverability is enhanced, and the unit is more responsive to steering, when compared to steering using only pure skid steering. Additionally, this USV uses pivot turns when the angle of turn is greater than a specific angle (can be set in the Pivot Turn Angle parameter). The pivot turn angle was selected as a result of extensive trials and was equal to 45°. The USV is equipped with an autopilot and the navigation position is calculated based on the autopilot’s internal sensors: three magnetic compasses (nine MEMS magnetometers), an inertial navigation system (INS) based on simple MEMS  sensors consisting of nine gyroscopes and nine accelerometers (compasses and INS embedded in autopilot) and an external GNSS receiver based on an UBlox M8N module. In that configuration, the USV position is calculated using an EKF . The EKF is a 24-state extended Kalman filter and the autopilot’s filter estimates the following states: altitude, velocity, position, gyro bias offsets, gyro scale factors, Z accel. bias, Earth’s magnetic field, platform body magnetic field, and wind velocity. For calculations in this study, the navigation autopilot used the EKF output position, which means that this was not a pure GPS reading, but filtered and estimated based on other internal sensors. Only one GNSS module based on the UBlox M8N module was used .The GPS RTK module readings are not used for navigation; the module is part of the hydrographic equipment and additionally, the acquired RTK readings were used as a reference and as an independent USV position registration. The GPS RTK receiver specifications are given in The experiments were divided into three phases. Phase one was data acquisition. In this phase three different patterns were planned and executed. The patterns were planned to represent typical hydrographic surveys based on the present unit (Pattern 1)  and the Phase two of the experiment concerned logged data filtration and preparation and evaluation of navigation GPS accuracy in the dynamic measurements. To prepare for this evaluation, studies described elsewhere  were useThe approach used the PL-2000 system (ETRS89/Poland CS2000 zone 6) which afforded the replacement of angular coordinates recorded by the GPS and RTK by Cartesian coordinates (in meters). This conversion (from angular GPS coordinates to Cartesian) allowed the calculations to be simplified and the results to be presented in meters. The PL-2000 coordinate system is Cartesian 2D coordinate system with northing (x) and easting (y) axes with orientations fixed to north, east, and units of measurement in meters.Navigation GPS maximal output frequency was declared as 5 Hz, which means that the GPS position  . In the r is a RTK to GPS measurement ratio calculated according to the following equation:The estimated positions are assumed to lie on the line joining the nearest registered positions of the estimated track with An example of a result for the GPS position interpolation is presented in The position of the unit for navigation purposes is taken from the navigation GPS placed on the top of the mast located in the geometric center of the USV. The GPS antenna location is determined by experience and typical recommendations for unmanned units; that is, the best place for navigations system is the geometric center of the unit and at the highest possible place to diminish interference with board electronics and ensure best satellite visibility. These actions were taken in the present study.For the hydrographic equipment, this consisted of a multi beam echosounder (MBES), a precise SGB IMU, and an RTK receiver. The best practice for that equipment localization is that the IMU sensors and the MBES antenna should be as close as possible, if not, all offsets should be entered into the system. In that case, the offsets represent coordinates in the local unit coordinate system of all hydrographic equipment including the GPS, the RTK antennas, and the IMU unit, where the IMU sensor is the coordinate system origin with the Y axis parallel to the unit long axis of symmetry . The hydGiven that the system navigation GPS is working out of the hydrographic system and for proper evaluation a vector between the RTK and GPS readings has to be included. The corrected GPS position was calculated from already interpolated GPS positions according to the following formula:c system .Having obtained all data at an equal rate, with the same coordinate system (PL-2000) and corrected the coordinates using antenna offsets, the navigation GPS accuracy may be calculated. Initially a Euclidean distance between the navigation GPS interpolated position  is defined as the distance between the planned sounding profile (planned USV track) and the actual unit position. The sounding profiles are represented by a line connecting two defined WPs. The final results represent the calculation process outlined above. Each profile was calculated separately. Based on the above calculation, the accuracy of dynamic navigation GPS was calculated in accordance with equations described elsewhere ,45 for eThe mean values for the research study are presented in Nonlinear guidance, originally designed for UAV trajectory tracking, has been adopted and used for USV trajectory tracking. This method allows us to keep a low XTE during all sounding profiles’ tracking; more importantly, the USV course changes that keep to the track are very gentle, and do not cause significant disturbances in hydrographic measurements. The trajectory tracking and the USV response for the calculated course inputs depend on the correct PID tuning. As stated above, PID tuning was carried out during extensive field tests. The configuration employed did not show any oscillations, the course changes although robust were gentle, allowing us to keep track within specified limits for the unit to weather conditions and wind direction. The correct PID tuning is very important for course and track keeping. As mentioned elsewhere , the USVThe position registered by the navigation GPS is not used directly by the USV for navigation. The pure GPS position readings are filtered using EKF and the final navigation position is calculated using all data available to the autopilot internal sensors. This technique is used widely within the robotics community to estimate a robot’s position. Consequently, the position used for navigation, as the results show, has good accuracy. The profile planned by the hydrographers, was followed based on GPS position. If we take into account the antenna position (in the center of the unit) and the offsets between the GPS antenna and the multibeam sonar (main hydrographic sensor) this causes quite significant differences between the real unit track and the sonar antenna track. The displacement differs and depends on the wind speed and direction. Practically, the profile is registered by the RTK system with offsets, therefore, from the hydrographic point of view, all data are registered correctly, however this difference can be diminished.As the results show, the accuracy of trajectory tracking based on nonlinear guidance logic is suitable for hydrographic USV profile tracking, and the presented unit configuration permits very precise track following with a mean XTE of around 30 cm. This is a very good result, if we compare this performance with a traditional manned hydrographic vessel. In the authors’ opinion, trajectory tracking based on nonlinear guidance logic for hydrographic measurements can be implemented on a wide variety of USVs providing correct nonlinear guidance logic and PID parameters.The difference between the track realized by the unit and the real sonar track can be significant and depends on wind speed and direction. This difference can be diminished using either software offsets or antenna physical displacement. The other approach is to use the RTK signal directly for navigation during the hydrographic survey.


Regenerative cryocoolers such as Stirling, Gifford–McMahon, and pulse tube cryocoolers possess great merits such as small size, low cost, high reliability, and good cooling capacity. These merits led them to meet many IR and superconducting based application requirements. The regenerator is a vital element in these closed-cycle cryocoolers, but the overall performance depends strongly on the effectiveness of the regenerator. This paper presents a one-dimensional numerical analysis for the idealized thermal equations of the matrix and the working gas inside the regenerator. The algorithm predicts the temperature profiles for the gas during the heating and cooling periods, along with the matrix nodal temperatures. It examines the effect of the regenerator’s length and diameter, the matrix’s geometric parameters, the number of heat transfer units, and the volumetric flow rate, on the performance of an ideal regenerator. This paper proposes a 2D axisymmetric CFD model to evaluate the ideal regenerator model and to validate its findings. The growth in a large number of low-temperature applications led to huge developments in cryogenics and particularly cryocoolers over the past few decades. Top applications among these are IR imaging, i.e., micro-cryocoolers for IR imaging systems , supercoThe regenerator is a vital component in any closed-cycle regenerative cryocooler, including the Stirling, Gifford–McMahon (G-M), and pulse tube machines. In pulse tube cryocoolers, the regenerator acts as a thermal storage component that transmits the pressure signal from the compressor to the pulse tube and other cryocooler components. It comprises a metallic porous medium that is subject to the periodic flow of the gas; where it is conventionally constructed of a thin hollow tube filled with mesh screens and/or metallic spheres, etc. The working principle involves thermal energy exchange between the working gas and the matrix material. To maintain considerable refrigeration, this matrix takes away the heat from the incoming gas during the heating phase and delivers it back for the returning gas during the cooling phase. The frequency of the gas flow can reach 100 Hz for a conventional PTC, but this should be significantly increased to serve any future miniaturized PTC design.In 1816, Stirling introduced the regenerative heat exchanger in a hot air engine . In 1927® and DELTAE®, which solve the conservation equations and hence describe the regenerator performance, are also often used. These numerical analyses have a range of complexity levels that depend on the assumptions employed and the degree of freedom used.Analytical and numerical analyses of critical components are required for the development of more efficient pulse tube cryocoolers, to replace potentially conventional concepts in existing or emerging application fields ,8,9,10. For all complexity levels, the design parameters of the regenerator, such as its diameter-to-length ratio, physical dimensions, pore structure, and matrix material parameters, impact the overall performance for any regenerative cryocooler. Normally, the design and/or optimization procedure of these parameters have been empirical, based on relatively rough lumped parameter considerations or the results of dimensional analysis. However, more complex numerical models should account for pressure drop, void volume, conduction losses, pressure variations, time-varying mass flow rates, time-varying inlet gas temperature, and temperature-dependent thermal properties. This paper presents a numerical approximation for the thermal interaction between the gas and the matrix material by only solving the energy conservation equations for both the matrix and the gas; the assumptions involve uniform one-dimensional longitudinal flow, with infinite radial thermal conduction and zero longitudinal thermal conduction in the matrix. It numerically solves the idealized general thermal equations for the working gas and the matrix based on finite-difference techniques and thus predicts the output temperature profiles for the working gas and the matrix material. Moreover, it studies the efficiency of the regenerator versus several design parameters of the regenerator. Finally, to validate the findings of the ideal regenerator model, the paper presents a 2D axisymmetric CFD model that solves the mass, momentum, and energy equations for the porous regenerator zone and provides more accurate results to compare it with the ideal regenerator model and examine its soundness.A large area for heat transfer can be obtained using inexpensive finely stacked material.The construction is relatively straightforward, and considerable savings can be made for the same heat exchanger duty.The regenerator tends to be self-cleaning due to the nature of the periodic flow reversals, and this is advantageous if contaminated gas is being processed.Well-designed regenerators can be achieved if proper design optimization procedures are in place.The regenerator is nearly analogous to a lossy spring that alternatively accepts energy and releases it when the excitation is removed. Another analogous model is a thermal flywheel accepting energy on the down-stroke and giving it back on the upstroke . In the However, the major disadvantage for static regenerative exchangers is the mixing of the hot and cold streams and is inescapable because of the carryover in flow switching . This coIn the regenerator, the temperatures of the gas and the pores vary with location and time. However, after several cycles of heating and cooling, a periodic steady state is achieved, as a result the nodal temperature at any location in the regenerator is equal to that temperature before/after one complete cycle at the same location. The expected temperature distributions for the gas and the matrix over one cycle are shown in c and releases it with high temperature Th. After the flow direction is reversed, the gas enters with temperature Th and leaves with Tc. In practice, the ideal regenerator case is impossible to achieve, where maintaining constant inlet/outlet temperature would need infinitely slow operation, or an infinite heat transfer coefficient, and/or a great heat transfer area. Furthermore, the heat capacity of the fluid and the matrix should be respectively zero and infinity. Moreover, the absence of a pressure drop would require a frictionless flow, while the absence of void volume would prevent the provision of flow passages through the matrix for the fluid to traverse [The ideal regenerator can be interpreted as a thermodynamic object that receives the gas during the heating phase with low temperature Ttraverse .h, The mathematical model used for this publication is based on simplified thermal energy conservation for the working gas and the matrix, as suggested by Ackermann . The oneckermann , where tThe model is then converted to two linear algebraic equations, which are used to compute the nodal temperatures for the matrix and the gas, hence predicting the regenerator performance and finally yielding:i and j are the number of spatial and time nodes, and Here, onstants :K1=hAs. The relation between the regenerator inefficiency (Ie) and the spatial and time steps is discussed in The regenerator’s effectiveness term measures the performance of the heat exchange process relative to ideal heat exchanging conditions. It is defined as the ratio of the actual heat exchanged between fluids and media to the ideal exchanged heat if no temperature difference exists between the two fluids at any position. The expression of the regenerator’s effectiveness in the case of balanced inlet and outlet flows is :(5)ϵ=Th,), where :(6)IneffThe model converges to a solution under two conditions. During the heating cycle, the final matrix temperature should not be higher than the outlet heating fluid temperature. During the cooling period, the final fluid temperature is not higher than the cooling outlet fluid temperature. This can be summarized mathematically as:From a mathematical point of view, the maximum time interval The number of spatial nodes is also significant in defining the accuracy of the computed variables. As the number of spatial nodes increases, the final outlet gas temperature during the heating period approaches the inlet gas temperature during the cooling period, thus decreasing inefficiency (Ie), as suggested by Equation . Figure The model is used to examine the effect of changing the regenerator dimensions  on the inefficiency (Ie). Second, it examines the implications of the matrix mesh screen parameters  on the performance of the regenerator and its inefficiency. A particular case is highlighted, with the following parameters: a regenerator of 7.5 mm and 30 mm in diameter and length. The regenerator matrix mesh size is a This section introduces a two-dimensional (2D) axisymmetric transient regenerator model to investigate the validity of the ideal regenerator model. The CFD model simulation was executed using ANSYS Fluent software since it is widely used for modeling and simulating fluid flows and heat transfer in various engineering problems. Although Fluent’s momentum, continuity, and energy governing equations are inaccessible for modification, Fluent allows users to program their user-defined functions (UDF) and to connect them to the primary model to modify boundary conditions, alter domain properties, or introduce variable sources or signals.The proposed system consisted of three zones: hot temperature zone, cold temperature zone, and porous regenerator zone. The model assumed that the hot temperature zone was contracting at a constant rate, pushing the hot gas inside the regenerator, while the cold temperature zone expanded at the same rate to maintain constant overall volume during the cooling period. After that, the hot zone started to expand, and the cold zone contracted to retain their original volumes as the cold gas entered the regenerator zone from the other side when the flow reversed direction during the heating period. The hot and cold temperature zones were designed to ensure that gas entered at L, zed from . Landrumzed from .® Core™ i7-5500U cores @ 2.4 GHz with four cores. The settings for the model were axisymmetric and laminar, and the working fluid was helium as an ideal gas. The numerical discretization schemes were second-order for the pressure, second-order upwind for both the momentum and energy, and with implicit first-order transient time formulation. The simulated flow time was 80 s, with a 2 ms time step size and 10 iterations per time step. The space element size in the dynamic mesh zones was set carefully to avoid negative volume calculation errors.The calculations reported here were performed using IntelThe dimensional and parametric analyses are of central importance for any efficient regenerator design. Although an abrupt change in the inefficiency was quite clear for diameters smaller than 0.01 m and lengths less than 0.03 m, the difference in the inefficiencies tended to be very small for diameter values above 0.025 m and lengths above 0.06 m. As a result, any attempt to miniaturize the regenerator element must take great care not to deteriorate its operation. The number of heat transfer units (NTU) is a non-dimensional parameter that expresses the regenerator’s heat transfer capacity. It is directly related to the size of the regenerator, its flow, and thermodynamic considerations. In a sense, if the NTU was large, the effectiveness of the regenerator would be high. It could be noticed that the inefficiency dropped with the increase in regenerator length and diameter, i.e., NTU increased as well, since the mass of the regenerator and its total heat transfer area increased as well. It is worth noticing that, in non-ideal regenerators, the axial conduction and viscous losses increases with larger lengths, and as a result, the inefficiency (Ie) also decrease.Mesh screens can be found in a variety of sizes , as illustrated in Total of 63, The model assumed that the regenerator temperature was initially at Although the ideal regenerator model was a simplified model built on various assumptions and limitations, it not only worked in predicting the thermal behavior inside the regenerator, but also to roughly estimated the effect of the design parameter on the regenerator’s performance. However, for more consistent and accurate results, 2D or non-ideal models are required for any design or optimization attempts for the regenerator element. Future work will extend the model to cover the non-ideal case and then compare it to different regenerator CFD models.® code was developed to study the thermal interaction between the working gas and the matrix material in a regenerator element, a component of a closed-cycle regenerative cryocooler. The presented algorithm was a discretization of the ideal regenerator thermal equations. Furthermore, a 2D axisymmetric model was presented to examine the validity of the ideal model and evaluate its findings. This study illustrated the unsteady behavior of the gas and matrix inside the regenerator. It was observed that by increasing the number of spatial and time nodes, the convergence of the algorithm was enhanced. The paper also investigated the effect of regenerator length and diameter on its effectiveness and studied the relation between changing the matrix mesh screen size and its wire diameter on its inefficiency (Ie). It further investigated the implications of changing the volumetric flow rate and the number of heat transfer units on the performance of the regenerator. It was found that these parameters had a significant effect on its inefficiency (Ie) and that an optimum could be sought under given constraints. Finally, the temperature profiles from the 2D model were compared to the ideal model. Future work is to expand the model to consider other substantial losses in the non-ideal case.A MATLAB


Breast cancer is the most common malignant disease in women. Compared with other cancer types, breast cancer has a higher survival rate. The majority of breast cancer patients are overstrained to implement cancer-specific recommendations relating to changes in health behaviour. Numerous epidemiological studies have shown a positive correlation between physical activity and quality of life as well as the course of disease during and after breast cancer treatment. However, many patients have difficulties integrating physical activity into their everyday lives due to cancer symptoms. To develop physical activity into a daily routine, an aftercare programme for breast cancer patients will be developed. In particular, the programme is structured in terms of the validated concept “Neues Credo”. The basic concept is converted into a mobile application.n = 740 rehabilitants (370 for the intervention group and for the control group) from five different rehab clinics in Northern Germany. The evaluation is as follows: a) Quasi-randomized, prospective longitudinal study . The intervention group receives a mobile application after rehabilitation, and the control group receives treatment as usual. The study evaluation is carried out through a questionnaire at three stages . b) Qualitative analysis of interviews and focus groups in terms of feasibility and acceptance. c) Formative evaluation of the app.The study sample includes Above all, the aftercare programme ReNaApp increases the long-term effects of oncological rehabilitation. By documenting physical activity in ReNaApp, rehabilitants become more motivated to engage in physical activity in their everyday lives. Currently, there is no scientifically evaluated app for breast cancer patients in the German language. Thus, ReNaApp ensures an aftercare treatment for breast cancer patients with high-quality performance regardless of their place of residence. By adopting a participatory approach and a user-centred design, ReNaApp corresponds to the demands of the rehabilitants.German Register of Clinical Trials, www.drks.de.DRKS00019017; Registered: November 7th, 2019.Identifier: Date and version identifier: April 17th 2020; vesion 2. With an incidence of 69,000 per year, breast cancer is one of the most common cancers that affect women in Germany . In partA number of authors have shown that physical activity is one of the most successful strategies in the course of an oncological disease. Physical activities increase the sense of well-being, quality of life and survival rate after cancer –6. MoreoMedical rehabilitation is one opportunity to initiate an active lifestyle after breast cancer , 12. To Although there is no aftercare programme for breast cancer patients, an effective approach for other diseases has been developed. Further studies validated the aftercare concept called “Neues Credo”, which introduces and maintains physical activity. The aim of “Neues Credo” is to increase the physical activity of rehabilitants and help them maintain this increased engagement for long periods . For insThe aftercare programme “Neues Credo” contains a complex intervention. First, the rehabilitants obtain coping skills together with other patients during rehabilitation. Simultaneously, the rehab clinics provide an educated aftercare agent whose task is to motivate the patients during and after rehab. In this context, the agents support rehabilitants in achieving their individual goals and maintaining physical activity in everyday life.While the concept “Neues Credo” only consists of a paper version, mobile applications for healthcare have been increasingly established in recent years. A reason for that is the rising importance of smartphones in the current society. For example, in January 2017, more than 54 million people over the age of 14 owned a smartphone in Germany. In other words, 62% of Germans use a smartphone . In addiRecently, there has been a growing interest in mobile health  applications that support healthcare services through smartphone/mobile terminals . ActuallDue to the great potential of mobile applications in healthcare, a need for evidence-based and high-quality applications arises , 21. PreThe aftercare programme “Neues Credo” complies with the needed theoretical foundation  and has This study aimed to integrate more physical activity into the life of breast cancer patients after rehab. (1) During rehabilitation, breast cancer patients are introduced to physical activities, define goals for the time after rehab and finally develop a plan for their implementation. (2) After rehabilitation, the patients install the ReNaApp, which includes an exercise diary, to reach their individual goals. In addition to the diary, the app encompasses tools for individual feedback, motivating functions and a comprehensive information area. (3) Consequently, the aftercare programme ReNaApp increases the physical activity of rehabilitants because of their greater motivation to permanently maintain the achievements of rehabilitation. More specifically, expectations in terms of improved social and professional participation, quality of life, return to work and general health are forecast over a period of 12 months.Initially, each of the participating clinics chooses one aftercare agent for the whole duration of the project. The agents will be trained concerning the recruiting strategy, the philosophy of the aftercare programme, and the handling of the ReNaApp. During rehabilitation, the intervention group (IG) will be supported by them.During rehabilitation, the participants of the study will receive a paper-based observation book. The observation book targets good preparation for the time after rehabilitation by the following three tasks: 1) self-monitoring: Which types of physical activity do I enjoy, and which physical activities make me feel good? 2) Which suitable physical activities exist, and which would I like to try? 3) What kind of physical activities are near my home?At the end of rehab, the patients will be invited to individually plan their physical activity according to their observation books: Which type of physical activities will I integrate and when? Therefore, the rehabilitants join a group for an hour to discuss the observation book with other rehabilitants and therapists. The therapists especially advise the preparation of personal plans for implementation and compliance. Within the group hour, all patients write a letter to themselves, which is sent by the aftercare agents to every patient 3 months post-rehab.As already mentioned, the aftercare programme encompasses a mobile application. ReNaApp is available on the web page of the involved clinics. During the class hour, the aftercare agents introduce the intervention group to downloading and using the mobile application. After logging into the app, the patients can use the application during the following 12 months. Related conversations with rehabilitants show that the use of a mobile application can expect high acceptance.Furthermore, ReNaApp contains additional features that are not included in “Neues Credo”. First, the app automatically generates feedback in relation to the executed physical activities. Replacement of the classic paper-based activity diary with ReNaApp, involves changes in both the medium and the time interval of the feedback. Concerning the participants’ activities, the type and frequency of notifications are adapted by the app. In the aftercare period, the rehabilitants receive motivational letters from their aftercare agents at regular intervals . In particular, the letters refer to maintaining physical activity or encouraging the rehabilitants to be more active.In addition, the control group obtains the standardized therapy during rehabilitation as well as in aftercare. During rehab, the patients supply care from their clinic regarding the existing standards. The Sixth Social Code implies that only functional training or rehabilitation sports are offered to oncological rehabilitants after rehab.All rehabilitants of the intervention group document their physical activity in the exercise diary in ReNaApp. This flexible procedure ensures that the quality and functionality of the mobile application works permanently.The currently available smartphones have a high degree of heterogeneity in brand, performance, display size, and software, with diverse operating systems. To include the largest possible number of smartphone users, ReNaApp uses frameworks and APIs that ensure compatibility with both iOS and Android operating systems, which include the vast majority of potential users’ devices. Because of impressive graphical frameworks and innovation in web technology, ReNaApp will be designed as a progressive web application (PWA) with a responsive design for automatic screen adaption , 30 and The user-centred design approach DIN EN ISSO 9241–210  ensures Like in the exercise diaries on paper, the patients will document their intentions regarding physical activity in ReNaApp. The documentation includes a selection of different types of physical activities, as well as custom activities. Furthermore, ReNaApp reminds the patients of their defined intentions regarding physical activity. Following a planned physical activity, the rehabilitants are requested to document whether they stuck to their plan and practiced physical activity for the full amount of time projected. Moreover, the patients record barriers, promoting factors and alternatives in terms of implementation problems.An alternative option for tracking physical activity is to connect health tracker devices and integrate their data. Previous research shows that approximately 74% of all these devices belong to either Fitbit or Xiaomi . Fitbit The second market leader, Xiaomi, only enables unofficial opportunities to transfer data via Bluetooth , 37. TwoTo avoid this problem, health-middleware services from both operation systems , i.e., Google Fit  and ApplIn addition to the data protection and technical difficulties of connecting fitness trackers, another reason for leaving out these devices is the idea of “Neues Credo”. The users should consciously plan and reflect on their physical activity. The automation of these steps by using a fitness tracker does not follow the aftercare concept. Furthermore, a bias would arise in the intervention group between users with fitness trackers and those without.The patients constantly evaluate their self-imposed targets at intervals similar to those in the paper-based exercise diary. Based on an algorithm in the app, the patients receive feedback from ReNaApp regarding their documented physical activities in comparison with the recommended time frame . The timAll patients from our five partner clinics with a reliable diagnosis of breast cancer will be included in this study (C50.0–.9 und D05.0–.9). Moreover, the rehabilitants must be between 18 and 60 years old, own a smartphone and have adequate German language skills.All rehabilitants who do not have a reliable diagnosis of breast cancer or who abandon rehab are excluded from the study. Other criteria for excluding participants are insufficient German language skills, missing declaration of consent and constraints in physical activity.The study is organized as a mixed-methods study  with dif0) and end of rehabilitation (t1) and 12 months after rehabilitation (t2). All patients will complete a written questionnaire using standardized, validated instruments.To examine the long-term effects of oncological rehabilitation with ReNaApp, the study is structured as a monocentric, quasi-randomized longitudinal study with three measurement points: at the beginning  until the desired number of cases is reached. After the recruitment of the control group, the rehab teams of all clinics are instructed in the handling of ReNaApp and the aftercare philosophy. The implementation of the aftercare intervention is accompanied by a fundamental change in the procedures and therapy regimens in clinics; therefore, recruitment of the control and intervention groups at the same time will not be possible. The later rehabilitants who fulfil the eligible criteria will be allocated to the intervention group. Based on preliminary interviews in rehab clinics, we assume that most of the rehabilitants own a smartphone and know how to use a mobile application.Restrictions for social and work-related participation will be captured with the IMET [the IMET . This vathe IMET , 44.Breast cancer-specific quality of life will be measured with the EORTC-QLQ-BR23 [QLQ-BR23 . The QuaQLQ-BR23 . The QLQReturn to work will be captured in a retrospective way with two single items. The rehabilitants are asked whether they returned to work after rehabilitation, and if so, how much time (in months) passed between rehab and return to work.After medical rehabilitation, a great number of patients return to work without major problems , 47. To Work ability will be measured with the Work Ability Score (WAS) of the Work Ability Index (WAI). This single item consists of work ability on a scale from 0 to 10, and a higher score indicates higher work ability. The WAS has been applied in numerous studies and has acceptable reliability and validity [validity .Occupational stress will be measured with the German version of SIBAR II and IV, and the overall burden and differentiated single burdens will be addressed [ddressed .subjective prognosis of gainful employment. Three items estimate the occupational risk of the patients. Adding the single items to form a total score, the patients can be subdivided into two risk groups. This scale has been validated in a large sample and is also reliable. Thus, the items have a good ability to obtain the subjective prognosis of gainful employment [The SPE scale in the German language considers the ployment , 51.Occupational changes will be measured with single items, including job-preserving interventions and types of job loss [job loss .fatigue will be measured by the EORTC-FA12, a questionnaire validated in a large international, multicentre study [Cancer-related re study . With thre study , a high Depressive state will be measured by the CES-D . The scale consists of 20 four-level scaled items regarding the presence and frequency of depressive symptoms. The evaluation is made according to a total score that can reach a maximum of 60 points. The higher the value is, the higher the expression of depressive symptoms. The CES-D is a reliable and valid questionnaire [ionnaire .performance in various areas of life will be assessed by three scales from 0 to 10 for the areas job, everyday life, and leisure. A high score implies high performance. The three single items are approved as a valid procedure for the determination of performance restrictions [The rictions , 56.physical activity will be assessed in connection with the questionnaire of the Federal Health Survey by Menski, 1998 [The extent of ki, 1998 . In addiki, 1998 , 56.The moderating variable is comorbidity , as wellOutcomes that cannot change during rehabilitation will be measured in the beginning and regard only catamnesis. These include outcomes regarding everyday life and the domestic environment of the patients  or insignificantly changed outcomes, such as medically determined comorbidities.Six rehabilitants will be interviewed by telephone at 3, 6 and 9 months post-rehab. From their personal point of view, they should assess the aftercare strategy, the use of ReNaApp, and the current status of the aftercare programme. At the time of catamnesis and written surveys, the interviewees will be asked about the utility of the app and their acceptance of and satisfaction with the use of ReNaApp. In addition, the patients will express their wishes and record them for further development or optimization of the mobile application and aftercare strategy. The interviewees will differ in age and education to assemble a heterogeneous group as much as possible .At the end of recruitment, several focus groups will be carried out with the aftercare agents and involved physicians of the five clinics. These focus groups will discuss the feasibility and practicability in clinical practice, the optimization possibilities, and the level of patient support provided by the ReNaApp.All interviews and focus groups follow a guideline. The guidelines and the results of the qualitative assessment will be presented and discussed within the project team and in the interdisciplinary expert forum “Arbeitsgruppe qualitativer Methoden” . The interviews will take approximately 30 min, while the focus groups will be longer. With the approval of every participant, the interviews and focus groups will be recorded and transcribed word by word. The subsequent evaluation will be performed according to the qualitative content analysis.Generating a high usability is the main focus during the development of ReNaApp. More than 10 patient representatives (breast cancer patients) will receive the developed prototypes of ReNaApp and execute exemplary tasks, i.e., documenting physical activity in the diary.The interactions with the system (prototype) have to be evaluated by objective data , subjective information about satisfaction and acceptance  and menThe aim of the health economic evaluation of ReNaApp is to determine the cost-effectiveness of the motion-based aftercare programme for women with breast cancer using an app (intervention group: IG) against the cost-effectiveness of a standardized rehabilitation measure with standard aftercare (control group: CG). Quantitative methods will be used to identify which intervention is more beneficial from an economic perspective. In addition, qualitative methods will be used to gain insights about factors that may enable or hinder aftercare implementation in rehabilitation clinics.The standardized implementation of health economic studies requires the consideration of various conceptual and methodological aspects.The basis of this analysis comprises data of the primary and secondary outcomes of the rehabilitation surveys at t0 and t2, supplemented by questions regarding service consumption and other benefit parameters. Standardized patient questionnaires will be used for assessment, as well as the costs of intervention implementation in the facilities by means of structured interviews with rehabilitation facilities’ staff.Proof of the advantage of the new intervention (rehabilitation model “Neues Credo” plus rehabilitation aftercare app) over the standard intervention in use (standard rehabilitation plus standard aftercare) will be provided by cost-effectiveness analyses, in which the effect parameters will be included in natural units  and via standardized and weighted uniform utility values  –69. Pre-In addition, so-called cost-utility analyses will be carried out based on quality adjusted life years (QALYs). Here, the intervention-induced change in health status will be evaluated with health-related quality of life (QoL) measures, e.g., QALYs. QALYs are interpreted as an index for lifetime gain and QoL - a QALY represents 1 year of life in optimal health . The incThe selection of relevant cost components is derived from the study hypothesis and the respective study perspective. For all studies, it is recommended that the analysis be carried out from a societal perspective to present the relevant benefits and resource consumption at a macroeconomic level. Additionally, the results that are relevant for the cost bearers (here: pension insurance institutions) should be added to describe possible divergences between the societal and cost bearers’ perspectives. The perspective of the patients is taken to identify possible influencing factors regarding consumption behaviour. Depending on the perspective, different exclusions are made for the cost and benefit parameters .In health economic evaluations, a distinction is made between direct and indirect costs. By definition, direct medical and non-medical costs include the consumption of resources by health care sectors and patients or their social environment that are directly attributable to the disease or impairment and valued in monetary units.For the ReNaApp study, the expected cost savings for both study groups from reduced service use in the 12 months after rehabilitation compared to the 12 months before rehabilitation (= net costs) will be determined. The difference between CG net costs and net costs, including the additional costs from the use of the new aftercare app (IG), will yield incremental costs.All patients will document volume data of the utilization of services in the questionnaires.Due to the lack of market prices, the evaluation of this database will be mainly based on prices administered by the state or agreed upon by association –70, 73. To fully determine the costs from a societal perspective, co-payments, deductibles or other forms of co-payment to be made by patients, as well as costs incurred outside the social insurance system, , will also be included.Indirect costs reflect the loss of value added due to the illness, valued in monetary units. From a pension insurance perspective, expenditure on rehabilitation and aftercare represents investments in maintaining earning capacity. To this extent, benefits for temporary and permanent reduction in earning capacity should be highlighted here. Costs arising from periods of incapacity to work on the part of the health insurance funds (sick pay) and employers (continued wage payments) and income losses from reduced working hours without financial compensation by the social insurance funds, e.g., reduced earning capacity pensions for female patients, are further cost items to be included. From a societal perspective, lost social security contributions also need consideration. In addition to these work- and employment-related productivity losses, ReNaApp accounts for reductions in performance in private life  to complete the patient perspective.Two valuation approaches - the human capital approach (HCA) and the friction cost approach (FCA) - are available for determining the costs associated with the performance and productivity reductions. Both reflect the societal perspective, but they account for productivity losses differently. The controversial discussion about the two methodological approaches has not been resolved, so the recommendation to apply both approaches and examine the different outcome effects in sensitivity analyses is followed , 68. BotFor the assessment of the loss of value added due to sickness-related absence from work, the average gross annual income from dependent employment for the total working population  is appliRegarding the inclusion of intervention costs in health economic evaluation, different positions are held in the literature (see ). For thStudy participants will be uniquely organized and documented in all clinics through an automated documentation template. All aftercare agents will be briefed on the template before recruitment.The included study participants will receive an identification number (ID) to pseudomize their personal data. The first number serves the classification of the intervention and control groups. The subsequent numbering corresponds to the number of addressed participants. Personal data will be only documented in an independent Excel file; by the ID, an appropriate linkage occurs. The data will not be sent to the ISE until the personal contents are deleted. This collection only serves the standardized documentation in the clinics. The data from the questionnaire will be collected and kept apart from the ISE.In the context of the quantitative part of the study, (A) data from the written survey will be captured by the acquisition software TeleForm®. The answers from the questionnaires will be scanned by this software and finally transmitted directly into SPSS 22.0. The unrecorded answers will be completed by a student assistant under the guidance of a scientific employee.This study does not contain drugs; ReNaApp investigates the health benefits of an aftercare programme fitted to the individual abilities of the patients. Therefore, no harmful or undesirable events are to be expected.Our study is accompanied and advised by a data and safety monitoring committee. An interim analysis is not planned.According to the time and primary outcomes, we expect that both groups (control and intervention groups) will similarly improve until the end of rehab. In the following period, the effects in the CG will approach the starting level before rehab, while the positive changes in the IG will stabilize and even increase slightly. We assume that the intervention group will return to work with higher likelihood and earlier than the CG.restriction in participation  will beon  on participation after a four-month follow-up. The IG participation in the controlled trial of “Neues Credo” showed an effect intensity of ES = 0.42 in a 12-month follow-up, and the control group showed an effect intensity of ES = 0.06. Psychosomatic rehabilitants reached an effect intensity of ES = 0.53 for participation after a four-month follow-up in the feasibility study of “Neues Credo”.social and work-related participation . To analyse each group of n = 235 patients, we must initially recruit 336 participants for the study; i.e., every rehab clinic has to recruit 112 participants (56 participants in each group).Calculating the sample size, we assume clinically relevant and positive effects (pre-catamnesis-ES = 0.40) in on (IMET ) in the on (IMET –81. To dn = 370 for IG and CG). Taking into account that 30% of those asked will refuse to participate in the study, 528 patients of each group must be addressed to participate in the study. In summary, each clinic will address n = 176 patients, 88 patients in each group. Because the study does not examine differences between the clinics, the rehabilitants of each clinic will be considered as one group at the end of recruitment.With propensity score matching (PSM), it is possible that not all participants will have a match despite the use of a caliper. The equalization of these matching failures justifies a 10% higher sample size; thus, 740 patients must be recruited  in different primary outcomes after rehab. In addition to a significant increase in social and work-related participation in the IG, breast cancer patients in the IG return faster and more often to work than patients following the standard aftercare programme. This is accompanied by lower indirect costs in the IG. Furthermore, the quality of life increases.The extent of restriction in social and work-related participation and the quality of life of the control group are comparable to the conditions of the intervention group at the beginning of rehab. Additionally, the participants in the control group returned to work less often and later than participants in the intervention group.Compared to the CG participants, IG participants using ReNaApp show significant positive effects in all secondary outcomes 1 year after rehab. This includes less physical, psychological and occupational stress as well as a better prognosis of employment and work ability.Last, the intervention group shows differences compared to the control group regarding a significantly stronger extent of physical activity 1 year after rehab. Unlike the patients in the control group, the breast cancer patients in the intervention group more often engage in self-engaged fitness training or sports programmes though the ReNaApp; they practice significantly more endurance sports.The aftercare concept “Neues Credo”, modified as a mobile application, aims to maintain the long-term effects of rehab of oncological rehabilitants. Focussing on high individual responsibility, the strategy also targets greater empowerment and self-control of the rehabilitants. During rehab, the participants are trained in these strategies. Afterwards, the rehabilitants transform into their own motivators and the experts of their own aftercare.The advantage of the new strategy is the time and financial relief for aftercare agents gained because of an integrated self-control and motivational feedback tool. The only temporal expenditure for the clinics regards sending motivation letters to the patients and, if necessary, providing contact in case of questions.The intervention ReNaApp will be implemented and evaluated in five oncological rehab clinics for breast cancer patients in Germany. In general, it is possible to transfer the intervention to other clinics. Undoubtedly, the developed mobile application could be adapted and expanded for other diseases. Thus, this app could support all people needing support in home exercise.To secure the transfer to mobile technology, information and materials are compiled for cost units and rehab clinics.First, it is possible that the disease worsens during and after rehabilitation. In this scenario, patients could contact their aftercare agents and review the personal aims and plans for physical activity and adapt them to the new situation.In the technical part of the study, the risk of failure of the mobile application exists. In this case, we have the chance to consult our experts of IMIS and ITM to, e.g., provide new updates for the application.Personal data will never be transferred from the application to the study leader or aftercare agents. ReNaApp keeps the information, statistics and documentation private.To ensure equal treatment for the IG and CG, all characteristics of the participants  and the disease  will be documented and compared between the groups. If differences arise between the two groups, they will be comparably integrated in the analysis . Based on our present knowledge, we assume that structural changes in the context of this project are very unlikely.


The function of language in high-order goal-directed human cognition is an important topic at the centre of current debates. Experimental evidence shows that inner speech, representing a self-directed form of language, empowers cognitive processes such as working memory, perception, categorization, and executive functions. Here we study the relations between inner speech and processes like feedback processing and cognitive flexibility. To this aim we propose a computational model that controls an artificial agent who uses inner speech to internally manipulate its representations. The agent is able to reproduce human behavioural data collected during the solution of the Wisconsin Card Sorting test, a neuropsychological test measuring cognitive flexibility, both in the basic condition and when a verbal shadowing protocol is used. The components of the model were systematically lesioned to clarify the specific impact of inner speech on the agent’s behaviour. The results indicate that inner speech improves the efficiency of internal representation manipulation. Specifically, it makes the representations linked to specific visual features more disentangled, thus improving the agent’s capacity to engage/disengage attention on stimulus features after positive/negative action outcomes. Overall, the model shows how inner speech could improve goal-directed internal manipulation of representations and enhance behavioural flexibility. A wealth of evidence shows that processing manipulable nouns and action verbs activates sensorimotor representations. Compelling results demonstrate that concepts and words are grounded in sensorimotor and affective systems. However, sometimes the focus on embodiment has led to neglect important effects of language on cognition. Within embodied cognition approaches, words have indeed been mainly intended as pointers to their referents—objects and entities in the world . Although this is undoubtedly an important role of words, language also plays other relevant functions for high-order cognition.The relationship between language and cognition is a long-standing issue at the centre of theoretical debate and scientific research. Recent years have seen the proposal of embodied and grounded views of cognition, according to which language is grounded in perception, action, and emotional systems  but also perception, for example helping humans to better recognise and categorise objects and entities18. Thus a growing amount of evidence is showing that different spoken languages influence the way we perceive time (e.g.20), colour , and pitch (e.g.24).Third, neo-whorfian approaches have reopened the debate about the idea that not only language in general but also the specific language we speak shapes the way we thinktool. First, in social interactions words can be used similarly to physical tools to extend the bodily space in relation to object reaching25. Second, words can also work as cognitive tools to affect our internal representations of the physical and social environment. The notion of language as a tool is not new, and it was introduced by distinguished authors as Wittgenstein26 and Vygotsky27. More recently, different authors have expanded this idea in different but similar directions (e.g.31). In particular, it has been highlighted that language can act as a cognitive tool. Language, both in its overt form of spoken utterances and in its covert form as inner speech, can ameliorate our thought processes, extend our memory, and support our prediction capabilities33.Language has also been proposed to be conceived as a sort of 35). Inner speech was first introduced by Vygotsky who proposed that it results from a developmental process leading to the progressive internalization of overt speech. Importantly for this work, the notion of inner speech has been later used in the context of working memory, in particular by stressing its role as a rehearsal mechanism that actively maintains information to support planning processes36. Current research focuses on different functions that inner speech might have, in particular in relation to cognitive control34 representing a relevant issue also investigated here. Moreover, recent literature has attested the existence of different kinds of inner speech, such as wilful/deliberative37 vs. spontaneous inner speech, condensed vs. expanded inner speech, monologic vs. dialogic inner speech, and evaluative/motivational inner speech35. Importantly for this work, some authors have highlighted the relationship of inner speech with second order cognition and metacognition38 and recent studies have investigated the relation between metacognition and the strategy changes adopted following error detection39. Despite these recent advancements on the impact of overt and covert language on cognition, the internal mechanisms supporting these processes are not fully clear and computational models as the one proposed here could support their identification.The notion of inner speech has a long history and is hotly debated in the recent literature  and deliberative/wilful (as supporting decision making). The model inner-speech component can be considered a form of metacognition—the system represents the chosen decision and evaluates it either positively or negatively, and this influences the strategy it will follow. In particular, the component strengthens working memory contents, as the phono-articulatory loop in Baddeley’s theory43, and plays a motivational role, as proposed by different authors who stress the motivational and self-reinforcing role of inner speech45. In our study we compared the model behaviour with the performance of human participants solving the Wisconsin Cards Sorting test (WCST), an important neuropsychological test directed to measure cognitive flexibility46 ask Fig. , top inv47. Human participants were psychology college students (average age: 20 years). The protocol used included three experimental conditions  Abstract working memory: this component stores the task sub-goals (sorting rules) chosen by the model, a function that in the brain is mostly supported by frontal cortices52; (d) Motivational system: this component uses the external feedback to update the information in working memory, a function that in the brain is mostly supported by ventral basal ganglia54; (e) Selector: this component chooses a sorting rule and biases the perceptual system , a function analogous to the top-down control that the fronto-parietal cortex, aided by basal ganglia, exerts on lower-level internal perceptual representations56; (f) Comparator: this component executes visual matching of the deck and target cards, based on the comparison of low-level perceptual representations of the cards by simulating the attentional/imagination processes of brain42; in the brain these processes might rely on a distributed network involving the frontal and temporal-occipital cortices57; (g) Motor system: this component controls saccades and actions displacing the deck cards close to the chosen target card.The model, which builds on a previous modelinner-speech component inspired by the brain networks that integrate linguistic and emotional information59. First, the component transmits information on the relevance of rules to the working memory, in particular information on the sub-goals (identity of the rule) whose priority should be changed, and the positive/negative valence, and intensity, of such change. Moreover, the component implements a phonological-loop storing the current rule independently of its possible pragmatic use.A key further part of the model is the https://github.com/GiovanniGranato/Flexible-goal-directed-behaviour-and-Inner-Speech.The key components of the model are implemented with neural networks whereas the ancillary components  are implemented by reproducing their functions in an abstract fashion Fig. . This seThe working memory is formed by three units with recurrent self-synapses. The self-activation decays to a baseline value (0.5) based on a decaying rate parameter The motivational component is supported by a reinforcement mechanism that increases or decreases the activation of the working-memory recurrent units. In particular, the component increases or decreases the activation of the unit that encodes the chosen sorting rule by an amount related to a parameter Deep Belief Network  composed by two stacked Restricted Boltzmann Machines . The component can encode the input (images of either the deck or target card) at different levels of abstraction. The component can also reconstruct (generate) the relevant aspects of the input, on the basis of the activation of its high-level units, through a top-down information flow supported by the DBN bidirectional connections. To this purpose, the last inner layer of the DBN encodes 12 possible attributes, divided into three groups corresponding to the three card categories .The hierarchical perceptual component is formed by a modified version of a deep generative neural network, in particular a soft-max function to compute the probabilities of selecting the different matching rules  leading to strongly activate only one attribute unit within the three groups of 4 units representing the categories  formed by an input layer, a hidden layer, and an output layer. This component receives a composite input from the selector (three units representing the chosen rule) and from the external environment . The output encodes the identity and valence of the last chosen rule, projecting, with one-to-one connections, to the working memory component. For example, if the model chooses the colour rule and receives a positive feedback, the language component causes an increase of the activation of the first unit of the working memory encoding the colour rule. Conversely, if the model chooses the colour rule and receives a negative feedback, the component causes a decrease of the activation of the first unit of the working memory. Analogous processes involve the working-memory form and size units in the case the system selects respectively the form and size rules. The language component is activated two times: a first time to implement a phonological loop storing linguistic information on the chosen rule; a second time to contribute to the feedback-dependent updating of the working memory content. In the first activation, the component is activated by the one-hot code from the selector, based on the current working memory content, and by a value of 1 at the level of the feedback unit (meaning ‘maintenance of the current rule’): this activation has the function of storing information on the decision rule within the phonological loop. In the second activation, taking place after the search and comparison of the deck/target cards and the action performance, the component is activated by the selector activation and by the external feedback: this activation contributes to update the working memory content in view of the next trial. The contribution of language to the working memory is regulated by a coefficient 62 for the simple simulator used to this purpose). The visual sensor is formed by an RGBY matrix that encodes a small portion of the environment, approximately covering one card per time, and represents the input following an attention-focused saccade onto one specific card. The motor component generates these saccades, in particular couples of saccades directing to the deck card and a target card, with the saccade couples involving the different target cards in sequence. Moreover, when the model detects a matching between the deck and target card it moves the deck card under the target card. Overall, the processes and behaviour of the model are as follows: (a) the working memory-selector-manipulator exert a top-down disinhibition of the attributes of the selected category; (b) the consequent card image causes the activation of one of such attributes through the bottom-up activation of the hierarchical perceptual component; (c) such attribute causes a top-down re-generation of the image pivoting on the selected attribute ; (d) the visual comparator gets as input the two reconstructed (selected-attribute dependent) images corresponding to the deck card and target cards, and compares them to check if they match (a matching is detected if the Euclidean distance between the pixel vectors of the two images is below a threshold); (e) in case of matching, the model displaces the deck card under the target card, otherwise it performs another couple of saccades until it finds a matching deck and target card; (f) following the card displacement, a simulated ‘external operator’ returns to the model a positive or negative feedback.The remaining components, computationally simplified, are relevant to support the interaction of the agent with the simulated card environment  to find the model parameters that best fit the human data in the three conditions of the WCST, namely the control, motor tapping, and verbal shadowing conditions. The parameters can be interpreted as the relative weights of the simulated cognitive traits of the model , and hence of the modelled human participants. Table We first focus on the parameter The control group has a very high The control and experimental groups show a higher distractibility value  between the model parameters, representing the strength of its cognitive processes, and the behavioural indices scored in the WCST Table .Table 2PThe We carried out an analysis of the simulations where the role of language was negligible  of the parameters of the control model. Table Both the EPM and IM do not show any statistical difference in the behavioural indices compared to the control model. This result suggests that high functioning language component (The VLM1 (impairment of the language contribution in case of negative feedback) showed a statistical significant difference with each index of the control model, with the exception of CC and FMS. In particular, the model showed a higher TE (The VLM2 (impairment of the language contribution in case of positive feedback) showed worse performances compared to both the INVM and control models. In particular, it showed a very low CC  did not show any statistical difference in any behavioural index compared to the control model. This suggests that the simple storing function of inner speech has not a relevant role in this task.The VLMG  exhibits the worst indexes with respect to all models. In particular, the model has a very low CC (47. The two control models have a similar good performance (they both solve the task in 80 rounds) but they exhibit a partially different internal functioning that highlights the role that language can play in the solution of the task  shows an erratic and inefficient internal functioning. In particular, it shows a lower superior bound of activation and sudden extreme activation changes that do not allow the completion of the test and produce several PE and NPE. Paradoxically, the erratic behaviour causes also random completions of categories . This result shows that the language contribution after a positive feedback supports the focus on a specific rule for prolonged times.The VLMG  showed an internal behaviour similar to an average behaviour of the previous two models. In particular, it exhibits a minor range of activation (inferior and superior bounds) and erratic changes of activities that prevent the completion of any category. Interestingly, this plot is qualitatively more similar to the one of VLM2 (positive feedback and focusing impairment) than to the one of VLM1 (negative feedback impairment), thus corroborating the previously discussed quantitative data indicating that the language contribution to focusing is more important than its contribution to processing feedback errors.The model proposed here highlights the specific mechanisms through which inner speech might enhance the internal manipulation of representations involved in goal-directed cognitive processes and executive functions. In particular, it accounts for the cognitive flexibility as measured in the Wisconsin Card Sorting Test (WCST).attentional focusing on successful goals . In addition, the comparison between the control model and versions of the model whose language storing function was lesioned did not show significant statistical differences, thus suggesting that the support of language for this function has a negligible role in the target experimental test. These results corroborate the importance of working-memory in flexible cognition as measured in the WCST, highlighting its role of ‘executive function’ rather than as mere information storage63. The results presented here thus suggest that inner speech can play a key role in enhancing the capacity of manipulating the states of working memory and thus to improve the effectiveness of goal-directed behaviour.Theory-driven statistical analyses, focusing on versions of the model having parameters involving a negligible role of language, highlighted the similarity of the functions played by feedback-based working-memory update processes, and those played by language processes, both capable of supporting the 64 further discussed in section "66.We also analysed the internal functioning and interaction of the system components. This analysis involves the control model with and without language and the language-lesioned versions of the model. Results indicate that the role of inner speech to enhance the executive-function role of working memory is based on its capacity to strengthen the activation differences between neural units which represent alternative possible goals . Once so differentiated, the internal representation carrying relevant information are more robust to lesions, distractions, and internal/external sources of noise. This ‘disentanglement’ function of language also manifested in a previous abstract non-embodied computational modelsuper-ordinate role of inner speech that involves both executive functions and perceptual embodied processes. In this perspective, inner speech represents a boosting internal cognitive ‘tool’, as highlighted by the psychological literature discussed in section “Overall, these results point to a possible Few scientific studies focus on the interaction between language and cognitive processes adopting a theoretical and computational approach. Here we review computational models that contribute to investigate this important topic.67. This model has high biological fidelity, simulating the neurophysiologically and anatomically grounded networks supporting the perception and production of speech. The model uses winner-take-all neural mechanisms to reproduce bottom-up attentional selection of words and non-words at different brain levels. However, the model does not investigate how goal-based top-down processes might affect internal representations. Another computionally more sophisticated model68, expanding the previous model, simulates the brain neural networks supporting decision-making processes for action and speech. The model is used to explain the spontaneous emergence of intentional speech acts in the brain. The model has the same limitations of the previous model and in addition investigates the influence of high-order processes on language but not the influence of language on cognition as done here.A first biologically grounded model simulates the brain networks supporting the interaction between attention and language69 links symbolic processing (words) to neural distributed representations and implements deep neural-network architectures involving sensory-motor learning and symbolic learning. The model investigates the top-down effect of symbolic computations on neural-network representations, suggesting that language can represent a ‘symbolic theft’ tool to improve categorisation. This model is not validated with empirical data as here and addresses a different investigation problem with respect to the role of language for the internal manipulation of representations.More abstract models investigate the interaction between language and cognition in particular focusing on the supporting role played by language for categorisation processes. A first model70 is based on an auto-encoder neural-network. The model is used to show how the injection of linguistic labels into the intermediate layers of the model can enhance its classification capabilities. The model has an abstract architecture that cannot be mapped onto specific cognitive processes and is not validated with empirical data, but it nevertheless proposes an interesting mechanism for which language can manipulate the internal representations of auto-encoder neural networks. Another computational model64 highlights a possible role of inner speech for cognition. The model in particular includes two simple neural networks that model a sensory-motor loop, learning to categorise objects, and a phonological loop, learning to repeat words. The two networks interact at the level of their intermediate layers. Although the simple architecture does not capture specific cognitive processes and the model is not validated with empirical data, the results show that self-directed language can enhance the disentanglement of internal representations for different categories of objects, a phenomenon also emerged here. A last model7 solves a sensory-motor classification tasks and shows how language can be used with vicarious functions with respect to visual inputs and to activate goals allowing to flexibly respond to stimuli. The model is qualitatively validated with empirical data but it does not investigate how language might influence the manipulation of internal representations.Three further models show mechanisms that use ‘linguistic labels’ to influence the computations of neural networks. The first modelOverall, compared to all aforementioned models the model presented here has an architecture directly capturing key high-level cognition processes. Moreover, it allows the study of how language can act as a cognitive tool supporting the manipulation of internal representations enhancing the interaction with the external environment. In so doing, it focuses on a superordinate role of language that can potentially explain its influence on many different domain-specific tasks . Due to these differences, the architecture represents a more accurate model of self-directed language for executive functions.This work investigates the interaction between self-directed language (inner speech) and goal-directed cognition through a computational model. To our knowledge, the model represents the first integration of inner-speech mechanisms within a cognitive architecture capable of manipulating internal representations that support goal-directed behaviour. The model reproduces human behavioural data during the performance of the Wisconsin Card Sorting Test, designed to study cognitive flexibility, both in a standard condition and in a condition involving verbal shadowing.The model allowed us to show how language can play key functions to support the cognitive processes, nemely the processing of external feedback and working memory. In particular, the model suggests that inner speech ameliorates attention engagement and disengagement with respect to specific goal representations after a feedback is received, and in general augments the disentanglement of goal representations. This ‘sharpens’ cognitive processes, making them more robust to lesions, distractors, and noise. Overall, the model reveals how self-directed language can strengthen the effectiveness of various cognitive process involving the manipulation of internal representations and thus improve cognitive flexibility and the interaction with the environment.Supplementary material 1