Sleep-disordered breathing, SDB, in children is associated with morbidity that can result in caregivers having to stay at home from work. The aim of this study was to investigate whether the number of days when caregivers are reimbursed, temporary parental benefit (TPB) to stay at home from work to care for their sick child is increased among children with SDB before and after tonsil surgery.n = 440), aged 2–11 years, that underwent tonsil surgery for SDB in day surgery at Sahlgrenska University Hospital in 2014 and 2015. TPB, was provided by the Swedish Social Insurance Agency. The expected days of TPB in the general population of the region were calculated. The number of days with TPB was compared 2 years before and 2 years after surgery and compared with the expected days of TPB.This is a retrospective, cross-sectional study of children (p < 0.001) than expected, but, when the 1st month after surgery was excluded from the analysis, there was no difference in days of TPB compared with the general population.Two years before surgery, the children had no more days of TPB than expected. Two years after surgery, the children with SDB had 4.8 more days with TPB (Children with SDB who had tonsil surgery had no more days of parental benefits 2 years before and 2 years after surgery than expected. SDB is associated with increased morbidity, but it does not appear to cause caregivers to stay at home in the majority of children. Sleep-disordered breathing (SDB) is a common disease in children. The prevalence is estimated at 4–11%, based on parent-reported symptoms –5, as weThe most common cause of SDB in children is upper airway obstruction due to adenotonsillar hypertrophy . Both suOne important aspect of the negative health effects associated with SDB and its treatment is whether or not the parents have to stay at home from work to take care of their sick child and whether that need is reduced after treatment. To our knowledge, this has not been studied before. Having to stay home to take care of a sick child imposes health-economic costs on the individual and on society at large, due to lost production and reimbursement provided to the caregiver. It could also be an indication of the severity of SDB-associated morbidity. Having to stay at home from work is, therefore, likely to add to the overall burden of paediatric SDB.In Sweden, a caregiver is entitled to temporary parental benefit from the government through the Social Insurance Agency (Försäkringskassan), as compensation for salaries lost when staying home from work to care for a sick child. The employment rates in Sweden have been over 75% for both men and women in the working age and more than 80% of children attend day-care centres until the age of five and then compulsory school. TPB can therefore be regarded as a relatively reliable measurement of how much children and their caregivers have to stay home due to the children’s illness. The aim of this study was to investigate whether days of TPB 2 years before and 2 years after tonsil surgery for SDB differ from the expected days of TPB based on data from the entire paediatric population of the region. The hypothesis was that, because of increased morbidity in children with SDB, there would be more days of TPB before surgery and that, after surgery, the number of TPB days would be comparable with the general population.This is a retrospective, cross-sectional study conducted at the Department of Otorhinolaryngology (ORL), Head and Neck Surgery, at Sahlgrenska University Hospital in Gothenburg, Sweden, a tertiary referral hospital serving an underlying population of approximately 1.5 million. Children with SDB due to tonsillar hypertrophy, aged 2–11 years, who underwent tonsil surgery, with or without adenoidectomy, at the Department of ORL in 2014 and 2015 were included. The medical records including the ICD-10 codes EMB10, EMB15, EMB20, EMB30 and EMB99 covering tonsillectomy (TE), tonsillotomy (TT) and adenoidectomy (A) in 2014 and 2015 were reviewed. Data on diagnosis, age, gender, general health and preoperative symptoms were recorded. Both tonsillectomy and tonsillotomy were included in the search, as both surgical methods are used in Sweden to treat paediatric SDB, with a predominance of tonsillotomy. In Sweden, the recommended surgical treatment for SDB is TE or TT + / − A, which explains why patients who underwent isolated adenoidectomy were not included.Because the objective of this study was to examine TPB data two years prior to surgery and two years after surgery, no children under the age of two were included. Children with SDB who needed in-patient care were not included in the study to avoid heterogeneity associated with specific medical syndromes or severe underlying disease. Children with a protected identity were also excluded. Children who underwent more than one tonsil surgery during the study period were only included once and the date of the first surgery was used as the pivot point.n = 36,273, were used to calculate the expected number of days of TPB in relation to age and gender during the observation period.TPB is available to all Swedish citizens. The insurance is limited to a maximum of 120 days of TPB a year for each child. The TPB is coupled to the child, so, for example, close relatives other than the parents who are employed can also receive TPB if they stay home from work to care for the child. In Sweden, the employment rates for both genders in the age group 16–64 years was 76% and 77%, respectively, in 2014 and 2015. During the same time period, 82% and 83% of children aged 1–5 were enrolled in day-care centres and older children were at school on weekdays. Children were not allowed to attend day care centres or school when they were ill and no medications, such as antibiotics or analgesics, were given at day-care centres or schools. Parents were unable to receive TPB if the other parent was on parental leave. The only situation in which both parents could use TPB at the same time was if the child was admitted to hospital. For reimbursement purposes, TPB could be used as whole days or part of days. In this study, however, all days (whole days or part of days) related to the child were treated as whole days of TPB. The total number of days with TPB was used as a proxy for the number of days the child needed to stay at home due to sickness during the study period. Data from the Swedish Social Insurance Agency on all children aged 2–11 years, registered in 2014 in the region of Västra Götaland, All Swedish citizens are identified by a unique social security number. Data on TPB for the children undergoing surgery were obtained from the Swedish Social Insurance Agency based on the child’s social security number in the medical records. Data on days of TPB were retrieved two years before and 2 years after the day of surgery for the children undergoing surgery. As tonsil surgery as such generates days with parental benefits during the postoperative care and recovery, TPB during the first 31 days after surgery were excluded from the analyses in a second step.The study was approved by the Regional Ethics Committee of Gothenburg, number 601–17.n = 36,723). The difference between the observed and expected number of TPB days was calculated and Fisher’s test for pairwise comparisons was used to test the difference between the observed and expected number of days. The results were shown in mean values and standard deviations (SD). Two-sided p values were used and p < 0.05 was considered to be statistically significant.The observed number of days of TPB two years before and two years after surgery was calculated for the 440 children undergoing tonsil surgery. The observed number of days was compared with the expected days of TPB. Age- and sex-specific expected TPB days were calculated for all the children in the same age interval in the region of Västra Götaland with the above 440 excluded (n = 49) and a long journey home (n = 1).From the medical records for 2014 and 2015, 834 patients were identified with the designated ICD codes. A total of 440 patients, 177 girls and 263 boys, met all the inclusion criteria and none of the exclusion criteria and were thus included in the study  had no registered days of TPB in the two years before and the 2 years after 2014. In the study group, 43 children undergoing surgery (9.8%) had no reported TPB 2 years before and 2 years after surgery.The baseline characteristics for the 440 children are shown in Table The main indication for surgery in all cases was SDB due to tonsil hypertrophy with or without adenoid hypertrophy. Forty children also had concomitant recurrent tonsillitis. Regarding the type of surgery, the most common procedure was TT + A in 369 children (83.9%), followed by TE + A in 44 cases (10%). In all, 16 (3.6%) underwent TT without adenoidectomy and 11 (2.5%) underwent TE without adenoidectomy. Twenty one children experienced a recurrence of tonsil hypertrophy after a previous tonsillotomy. Fifteen of them underwent a tonsil surgery a second time during 2014–2015, (7 TT and 8 TE). Six children underwent two tonsil surgeries during the follow-up period (3 TT + TT and 3 TT + TE).Thirty-seven (8%) patients experienced postoperative complications during the first month after surgery. Fifteen children had a postoperative infection that required treatment, ten were admitted to hospital due to bleeding, two had bleeding but were not admitted and ten contacted the hospital because of pain.In this study of children with SDB undergoing day surgery on the tonsils, with and without adenoidectomy, there was no increase in the number of days the parents had to stay home with their child due to sickness, 2 years before and 2 years after surgery, compared with the expected number of days, calculated from data on TPB in a large population of children.Although children with SDB are known to have associated morbidity and affected quality of life , 13, theThe increased health utilisation seen in children with SDB due to an increased number of upper respiratory tract infections (URI)  did not Only children undergoing surgery in day surgery were included in the study. As a result, none of the children included in the study had other serious illnesses, syndromes or severe obstructive sleep apnea (OSA), as those children are usually admitted to inpatient care. Had they been included in the study, we would have seen a larger number of TPB days, probably both before and after surgery, which would have affected the results. During the first 2 years after surgery, the SDB group had 4.8 more TPB days than expected, which is statistically significant. As such, however, surgery to the tonsils does generate days of TPB in the recovery period of the child. For this reason, the calculations were also made with the first 31 days after surgery excluded in the follow-up period 2 years after surgery and the difference in the number of TPB compared with the expected number then disappeared. The 4.8 days’ difference during the first month after surgery is likely to be associated with the postoperative recovery of the child and is also comparable to the TPB use related to tonsil surgery found in previous studies .TPB cannot be seen as a completely reliable measurement of morbidity. It does, however, tell us how many days caregivers have had to stay home from work due to their children’s illness and may thus give us an idea of the economic effects of caregivers having to stay home to take care of their sick children. These effects do not appear to be greater in children with SDB compared with the rest of the population.It is important to highlight the fact that tonsil surgery in SDB has been proven effective in treating SDB symptoms , 16. It The use of TPB in this study as a proxy for morbidity was founded on the prerequisite that the majority of parents of young children, both men and women, were employed in Sweden during the study period. If they had had to stay at home with a sick child, it is likely they would have used TPB reimbursement for lost salary. Moreover, TPB insurance is available to all parents, as well as other caregivers of the child who are employed . The weakness of using TPB as a proxy for morbidity is that the caregiver decides when to stay at home and no doctor’s examination is required. This could result in misuse and, according to one report from the Swedish Social Insurance Agency, the level of cheating in the TPB system is around 14%  indicating that the problem is minor and should not differ between the groups.One important strength of this study was that we were able to use data from the entire population of children in the region to calculate the expected days of TPB and that this cohort comprised more than 36,000 children.One weakness when using TPB in this context is that caregivers may already be at home due to unemployment, their own illness or taking care of another child, but there is no obvious reason why these conditions would differ between the children with SDB and other children.The TPB data do not enable us accurately to describe what morbidity of the child caused the parent to stay at home. Further research is needed based on primary care data and self-reported symptoms associated with children with SDB staying home from day-care centres and school.In this study of children with SDB undergoing day surgery to the tonsils, with and without adenoidectomy, the number of days the parents had to stay home with their children due to sickness, 2 years before and 2 years after surgery, was comparable to the general child population in the same region. Although children with SDB are known to have increased morbidity associated with SDB, the need for caregivers to stay home from work to take care of their children does not appear to be greater.


Since the established correlations between mechanical properties of a piece of wood at the macroscopic scale and those of the cell wall at the submicron scale, techniques based on atomic force microscopy (AFM) have become widespread. In particular Peak Force tapping, allowing the differentiation of various layers, has become the new standard for wood cell wall’s nanomechanical characterization. However, its use requires fully elastic indentation, a good knowledge of stiffness of the probe and assumes a perfect tip shape of known radius (sphere) or angle (cone). Those strong hypotheses can result in large approximations in the extracted parameters for complex, nanostructured, and stiff and viscous materials such as wood. In this work, we propose a reliable and complementary alternative based on AFM force-volume indentation by refining the Oliver and Pharr nanoindentation processing and calibration procedure for AFM cantilever and tip. The introduced area-function calibration (AFC) method allows to considerably reduce these approximations and provides semi-quantitative measurements. No prior knowledge of the tip shape and cantilever stiffness are required and viscoplasticity is investigated through a qualitative index. Indentation parameters variations are shown to impact the resulting measurements, i.e., indentation modulus, viscoplasticity index, adhesion force and energy. AFC method, applied to map regions of tension wood, provides very stable mechanical parameters characteristic of each region, which makes this method of high interest for plant cell wall studies. However, what prevents a generalization of the use of these materials is, among others, the wide variability of their mechanical properties. Variability at the scale of the work-piece is heavily influenced by the variability at the fiber scale2. Indeed, wood is a multi-scale material whose mechanical support function is ensured by the fiber’s walls. Wood cell walls can be seen as a multi-layered composite material in which partly crystalline cellulose microfibrils act as a unidirectional reinforcement. These microfibrils are oriented at a specific angle to the direction of the fiber  whereas the matrix mostly consists in amorphous lignin and hemicellulose6. In the so-called “normal” wood, the secondary layer (S2)  and of  mostly hemicellulose for the matrix11. In addition to the industrial interest, knowledge of the mechanical properties of wood at parietal layers’ scale presents a fundamental biological interest for understanding the state of stress within the living tree, and, in particular, for providing information on how the G layer leads to the generation of maturation stress12. Different hypotheses exist to explain this phenomenon, but the lack of micro/nano-mechanical data does not allow to clearly understand how stresses and strains develop within each layer during maturation  and how they are transferred from one layer to the other to explain the stress observed at the macro-scale. Wood mechanics has become an important field of investigation in correlation with the raising circular green economy and industry. Natural fibers are, for example, increasingly considered as an alternative to glass fibers in composite materials with polymer resins13 at the cell wall scale. However, indentation leads to a complex mechanical stress state, consisting of compression in the direction of indentation and both compression and shear in the transverse direction. Furthermore, because the wood cell wall is not an isotropic material, indentation does not allow a direct determination of elastic constants of the tested material, but only provides an indentation modulus (M) resulting from the combination of these elastic constants, as it has been shown theoretically16. These theoretical works have already been applied to wood, allowing to estimate the elastic constants from successive indentation tests, and to deepen the understanding of the mechanical behavior of wood at the level of the cell wall17. Since traditional indenters do not allow resolving the thinnest parietal layers (like the compound middle lamella CML of the order of 100 nm), the use of atomic force microscope (AFM) has become widespread for carrying out nanomechanical tests on plant cell walls using nanometric size tips as indenters. Mechanical properties mapping is an increasingly common feature in AFMs. Peak force quantitative nanoscale mechanical characterization (PF-QNM) or quantitative imaging (QI) present the advantage of reducing the volume of indented material, achieving excellent spatial resolution (indentation depth < 5 nm) and acquiring maps of mechanical properties at high speed22. These technics are based on an intermittent high frequency contact mode (>> 100 Hz) coupled to the choice of a model describing the mechanics of the contact between the tip and the indented material. The elastic indentation modulus is then extracted by adjusting its value to fit at best the force–displacement curves acquired with the chosen model. Various models, such as Hertz, JKR, and DMT, exist for simple tip geometries , interacting with an indented volume considered as a flat half space. These models are only valid for contacts remaining in the elastic domain24, therefore, making impossible the study of viscoplastic behavior. Indentation depths associated with the PF-QNM mode are generally very small, very often less than the radius of the tip. However, because of surface roughness (due to the samples surface preparation) and of the small radius of curvature of the tips (necessary to reduce the contact area and to increase the resolution), the hypothesis of an elastic contact is not always verified. Thus, measurements can be biased if the contact regime is not perfectly elastic or if the shape of the tip is poorly determined. In addition, the extraction of the indentation modulus by this method is highly dependent on a precise determination of the cantilever stiffness, which is particularly difficult when it exceeds 20 N/m25, yet necessary to have a cantilever stiffness in the same order of magnitude as the indentation stiffness of wood cell walls. In order to limit these difficulties, it is recommended to determine beforehand the contact radius of the tip used on a reference sample with a known indentation modulus21 or with a calibration grid sample28 for a given indentation depth.Nanoindentation has been widely used to perform mechanical characterization in wood science since 199731 coupled with a method of calibration of the tip that we named area-function calibration method (AFC) using a reference sample. Mechanical measurements made using FV mode and evaluated with Oliver and Pharr method have already been performed on several materials such as pulp fibers32 or metal nanosheets33 for example. They are highly affected by various parameters such as surface roughness , cantilever calibration or the model used to describe the geometry of the tip. Our aim here is to refine this procedure by establishing a calibration and processing method to limit the source of potential errors and by studying the influence of indentation parameters on the calculated mechanical properties. Acquisition of indentation curves in FV mode is slower than in PF-QNM but offers the possibility of measuring the indentation modulus without requiring the hypothesis of perfectly elastic indentation. In addition, the AFC method makes it possible to determine the indentation modulus independently from the knowledge of the cantilever stiffness and also avoid the need to know the real shape of the tip beforehand, it therefore allows the use of atypical ones. It consists in building a tip/surface area function, i.e., the tip/sample contact area versus the indentation depth function, using a reference sample of known indentation modulus with a low surface roughness. Moreover, as the average indentation depth can be greater and the indentation times longer in FV indentation than in PF-QNM, the viscoplastic behavior of the material can be investigated. This is another attractive point of the presented method. We use a qualitative index characterizing the viscous and plastic behaviors of the indented material23, two properties of plant cell walls that are yet largely unknown at this scale. Furthermore, the adhesion is measured both as the force and the energy required to detach the tip from the indented surface. We focus on the comparison of these two computing methods and on the interpretation of such measurements applied to wood cell walls.In the present work, we propose an alternative procedure, complementary to PF-QNM, based on AFM Force-Volume (FV) indentation mode with a data processing method adapted from the one traditionally used for nanoindentationIn order to validate our method, our protocol is applied on two types of parietal layers found in poplar: S2 layers from opposite wood (OW) cell walls and G layers from tension wood (TW) Fig. . Two typS at the maximum of the unloading curve , is an improvement of the popular Oliver and Pharr30 method for processing FV curves.Both AFC tip calibration and data processing methods are described in detail in the “rve Fig. a without34 to acquire quantitative viscoelastic information using AFM nanoindentations. The later requires however very strong hypothesis  and long measurements (600 s/measurement) that are not suitable for mapping. On the contrary, our approach consists in reducing the amount of hypothesis at the cost of having qualitative results rather than quantitative. The last parameter, adhesion, i.e., the force (Fadh) or the energy (Eadh) needed to separate the tip from the surface, reflects the interaction between the tip and the surface and can be used to deduce chemical information from the investigated sample. Although very common, this parameter has not been extensively investigated in the case of wood samples; we will show here how this parameter can be correlated to the chemical composition of each layers of the cell wall.In addition to M, two other parameters are extracted and will be found useful to discuss the properties of wood samples later in the manuscript. The viscoplasticity index (VPI) is a qualitative index which represents the weight of the viscous and plastic components in the material response to indentation. This parameter, which is rarely exploited in AFM nanoindentation experiments, has been very useful to describe the viscoplastic properties at the nanoscale independently of the elastic properties. Our method is complementary to the method developed by Ganser et al.To validate our data processing method, we carried out sets of indentation measurements in the G layer of the tension wood cell walls, using the two different probes, while varying the indentation depth. The number of indentations per set of measurement is limited by the width of the investigated layers (less than 1 µm). To avoid overlapping solicitated volumes, the number of indentations was limited to 3 × 3 grids replicated 3 times for a total of 27 indentations.hc ranging from 5 to 30 nm for the DT probe and from 8 to 53 nm for the PPP probe. These two ranges of indentation depths are given by the experiment itself, the lowest values correspond to the limits for the contact detection and the highest ones to the cantilevers’ deflections linearity limits. For a given material, these ranges are hence cantilever and tip dependent.For both probe types (PPP and DT probes), indentations were performed and processed using our area-function calibration method described previously . Below the 10 nm limit, the modulus seems underestimated. Since the mechanical properties shall not depend on the depth of indentation in the parietal layer, this observation may be due to surface damaged by the cutting process or to surface roughness. Indeed for small indentation depths, the roughness has a great influence on the volume of material loaded resulting in an over-estimation of the contact area. For large indentation depths, i.e., hc > 35 nm for the PPP tip and > 25 nm for the DT tip, the measured modulus drop could be explained by a change of indentation regime between the reference resin and wood cell walls, as well as microfibrils buckling under high loads38. Another explanation would be that the solicitated volume can overflow into less rigid regions, reducing the measured indentation modulus M. This effect was already highlighted39, with Berkovich nanoindentation for higher indentation depths (> 300 nm). It is therefore crucial before any FV measurements, to check for the adequate range for which the indentation modulus is independent from the indentation depth.The first observation is that the AFC method allows the extraction of the indentation modulus, here ~ 16 GPa, independently from the type of probe and indentation depth in a specific range. This range goes from 10 to 35 nm for the PPP probe and from 10 to 25 nm for the DT probe  while keeping the cantilever vertical displacement identical for each measurement. We started by measuring the effect of t on the indentation depth hc , which is shown to increase as well with the indentation time  up to 1.2 s (for a maximum indentation) due to the control of the cantilever’s displacement. However, comparison with results obtained while varying the indentation time makes it possible to isolate the influence of time and indentation depth.As shown previously in the Comparison of indentation modulus extracted with a geometric model or following the AFC method section the indentation modulus exhibits a plateau, ranging between 10 and 35 nm for the PPP probe and between 10 and 25 nm for the DT probe, which corresponds to the adequate indentation depths to perform a correct measurement for a given tip  and an indentation time of 0.02 s. The second set, set 2, follows the recommendations with an indentation depth and time of 10 nm and 0.7 s respectively. With these two sets, we performed two mappings of the same area at the intersection of three cells in tension wood using the PPP probe. An acquisition of the topography of the indented area was carried out between the two series in order to check that it was not damaged  can be explained by the high roughness in these areas due to cutting effects during sample preparation. These areas do not bring significant information and are therefore excluded from the analysis Figs. e–h.35. In contrast, the indentation moduli in the S2 and S1 layers vary significantly depending on the portion of the cell observed (14–18 GPa for S2 and 9 to 14 GPa for S1) this difference can be explained by a variation of the microfibrils angle (MFA) at the surface generated by a cutting angle not perfectly perpendicular to the fiber angle as described in41. Note that the indentation moduli in the S2 layer is sometimes higher than those obtained in the G layer  than in other layers. In the case of negligible contribution of plasticity, these results are in agreement with damping factor (tan δ) mapping obtained by CR-AFM on chestnut TW at much larger loading frequencies35. They also partially agree with macroscopic viscoelastic dynamic characterization (DMA) of tension wood versus normal wood of tropical species43 at similar loading frequencies, where viscosity of TW was found higher than of OW's . Finally, even if VPI cannot be directly associated to creep behavior because of the plasticity contribution, our results are in agreement with recent studies using Berkovich nanoindentation creep test studies44 in which viscosity in normal wood was found higher in S2 than in CML.ell Fig. f, even t23. Since the contact area is not known during the adhesion phase, it is impossible to know precisely the proportional factor between these two quantities. However, it can be seen that the ratio of the adhesion force to the adhesion energy is almost constant, whatever the location on the wood cell wall (between 2.3 and 2.5). Thus, whatever the parameter (force or energy) used to study adhesion, we observe a clear trend such as AdhG > AdhS2 > AdhS1 > AdhCML  than in S2, which is itself more important than in the CML45. Our measurements are in adequacy with the hypothesis that adhesion in ambient conditions reflects the affinity of the indented surface with water: a stronger adhesion corresponds to a more hydrophilic material. In the case of wood cell walls, this can be interpreted as an area rich in (amorphous) hemicellulose (cellulose molecules are rich in hydroxyls groups that give them hydrophilic properties), especially in the case of the G layer with a gel-like structure12. The local roughness, of the surface and of the tip apex, which is also known for having a huge impact on adhesion measurements46, is estimated from a topographic map of the area acquired using the AFM in semi-contact mode. Average roughness (Ra) which ranges between 1 and 2 nm for G, S2 and CML shows no significant differences between these layers   method, allows to considerably reduce the approximations on materials elastic modulus resulting from a bad knowledge of tip shape and cantilever stiffness usually encountered with AFM force-volume measurements and open the path to semi-quantitative analysis. This reveals to be particularly useful to study (relatively) stiff materials, such as wood cell walls or other inorganic materials, requiring the use of cantilevers with a high stiffness, which is difficult to precisely determine. In addition, it opens the possibility for using probes not usually dedicated to indentation, such as diamond coated probes with high surface roughness or atypical probes with weird shapes.Application of the method to an indentation mapping over a tension wood region allowed the quantitative mappings of the indentation moduli. It was established that the viscoplasticity index (VPI) depends both on the viscous and plastic behaviors of the indented material and turned out to be a stable and significant parameter complementary to elastic indentation modulus. Finally, adhesion was found to reflect the cellulose content through hydrophilicity and could be used as a complementary approach to other chemical mapping techniques (such as RAMAN spectroscopy) which do not allow such great spatial resolution. Thus, force-volume indentation with the presented method has proven to be a rich toolbox to study various physical, chemical properties and to carry out correlations to deepen our knowledge of wood cell walls.We believe the AFC method brings the use of AFM force-volume mode to a higher standard where the extracted indentation moduli are semi-quantitative and we are convinced that it will be very useful to anyone interested in the nano-mechanical properties of complex materials.Populus euramericana, “Robusta” and “I214” blend) cultivated in open-field and constrained with a tutor after two months of growth to induce tension wood generation , which is itself necessary to avoid the collapse of the gelatinous layer of tension wood48. Ethanol has been shown to be the solvent which minimizes the damages to the G layer49. LR-White has been chosen as the embedding resin that has reduced penetration into wood cell wall, leading to no change in mechanical measurements at the nanometer scale50. Resin inclusion is then obtained by soaking the matches overnight in a 1:1 Ethanol:LR white mixture at room temperature, followed by two successive resin baths for 1 h and 2 h respectively. Subsequent polymerization is carried out in an oven at 65 °C for about 24 h.Surface roughness is a critical parameter when it comes to AFM indentation measurements. As a result, the great challenge in sample preparation is to reduce this roughness as much as possible. Our procedure is the following: sample preparation starts with a 1 cm thick stems sections cut with a saw. Matches of an approximate size of 4 × 1 × 1 mma), computed from topographic images produced in semi-contact mode by AFM  is performed as best as possible perpendicularly to the axis of the fibers. The surface is leveled and the next 100 µm cut with a glass knife. Finishing cuts are carried out using an ultra diamond knife (RMC Ultra) . With such procedure, the local roughness , is not usually used for nanoindentation tests because of its irregular surface caused by a diamond coating to make it harder and limit its degradation. Its radius of curvature is estimated to 110 nm and presents a high surface roughness of a few nanometers. The half cone angle is 20° and the stiffness of the cantilever is estimated at 70 N/m after calibration by the manufacturer. The values taken as mechanical constants for the diamond are: Ediamond = 1200 GPa and νdiamond = 0.252.Two types of tips were used: PPP-NCHR (PPP) from Nanosensors with a radius of curvature of 5 nm as assessed by scanning electron microscopy (SEM) measurements and a half-cone angle of 20° (manufacturer's data). We verified, using the area-function, that the shape of the tip remained unchanged after measurements. The calibration of this tip using the Sader's method gives a stiffness of the cantilever of 22 N/m. For the tip, made of silicon without any coating, elastic modulus and Poisson’s ratio of silicon are used as mechanical constants of the tip, i.e., E53:M the indentation modulus, F the maximum force applied by the tip on the surface, hmax the total indentation depth and hc the effective indentation corresponding to the contact depth ,,2), the 54. It is shown here that this value does not impact indentation modulus determination.Conversion from deflection curves as a function of the displacement of the piezoelectric element to force curves as a function of the depth of indentation using the cantilever sensitivity (cantilever displacement versus deflection) measured beforehand on a sample considered to be infinitely rigid (here flat Silicon). Cantilever stiffness values provided by the manufacturer or obtained using Sader’s methodSmoothing using a Savitsky–Golay function to overcome measurement noise.Subtraction of the force baseline.0 at the beginning of the unloading curve to reduce the effects of viscosity and plasticity.Determination of the slope SFor each indentation curve, the four-steps processing goes as follows:0 is critical and may influence drastically the resulting values for the elastic modulus. The methodology that we have set to extract this slope is discussed in the following. Oliver and Pharr30 recommends fitting the unloading curve with a power law of the form 24. To overcome this difficulty, S is sometimes approximated by a linear regression, however, the range chosen to fit the unloading curve greatly influence S’s determination24. We choose here a compromise between the two methods: the entire unloading curve is adjusted with a mth degree polynomial and we determine S as the maximum value of the derivative, i.e. corresponding to the slope at the beginning of the curve  is introduced to take the indenter geometry into account.To take into account the phenomenon of surface deflection during indentation Fig. a, we assmula Eq.  with:5\dε equals 0.72 for a conical shape, 0.75 for a parabola of revolution and 1 for a cylindrical flat punch30. However, because the shape of the tip is not always well known or does not match the simple geometrical models, we investigated the effect of the value of ε on the resulting indentation moduli. We show that these moduli have a relative variation of 10% at most for extreme values of ε ranging from 0.5 to 1, thus showing that this parameter has little influence on the final determination of the moduli  is obtained by fitting the curves by a degree 3 polynomial function ,,5), we pThe indentation curves on the plant walls are processed in a similar manner to those of the reference sample described above. In addition to the 4 steps described previously, the last step consists in determining the remarkable points that are required to extract the different physical quantities : contact point (A), start of the unloading curve (B), end of the indentation (C), maximum adhesion (D), end of the adhesion (E) as pointed in Fig. As for Eq. , and usiA and S from Eqs. (By developing rom Eqs.  and 3),,A and S 55. Indentation modulus results from a combination of the elastic constants56, and is expressed as follows to take tip deformation into account30:Since the plant cell walls are strongly anisotropic materials  and that indentation test produces a complex loading, essentially composed of compression in the direction of indentation and compression and shear in the transverse direction, we cannot directly extract a Young's modulus, e.g., the longitudinal or transverse modulusVPI) defined as: VPI = 1 − A2/(A1 + A2)  corresponding to the energy preventing the tip to detach from the sample during tip withdrawal , as well as the cutting angle (sample preparation dependence). This latter causes a variation of the microfibrils angle at the surface as a function of the indentation position around the cell41.Since the walls of wooden cells are comparable to a transverse isotropic material along the microfibrils direction, the angle of the microfibrils on the surface is a parameter of paramount importance influencing the value of the measured indentation modulus and associated mechanical parameters. An indentation carried out along the axis of the microfibrils results in the determination of a larger indentation modulus than for an indentation performed given a different angleAlthough the purpose of the accurate cut is to be perpendicular to the direction of the natural fibers as best as possible, a small variation can have a large impact on the measured modulus. In order to limit this variability or to evidence the cutting angle impact, we acquired each set of indentations by replicating it 3 times at different positions around the same cell, or a neighboring cell.Each set corresponds to 9 indentations arranged in a 3 × 3 grid with a gap between each indentation in order to avoid overlapping imprints and solicited volumes (Supplementary Fig. Supplementary Information.


CTF) of a lens via virtual Fourier filtering followed by a phase retrieval algorithm. We design and realize a phase mask which when placed at the pupil plane of a diffraction-limited lens produces a superoscillatory hotspot with sidelobes properly matched to the field of view (FOV) required in microscopic imaging applications, i.e. hotspot always coexists with huge intense rings known as ‘sidebands’ close to it and hence limiting the FOV. Our technique is also capable of extending the FOV with minimal loss in resolution of the hotspot generated and considerable ratio between the intensity of the hotspot to that of the side lobes while optimizing the obtainable FOV to the requirement of microscopy.Superoscillation is a technique that is used to produce a spot of light (known as ‘hotspot’) which is smaller than the conventional diffraction limit of a lens and even smaller than the optical wavelength. Over the past few years, several techniques have been realized for the generation of the superoscillatory hotspot. In this article, for the first time to the best of our knowledge, we propose a novel and a more efficient technique for producing superoscillation in microscopic imaging by shaping the Coherent Transfer Function ( NA) of the objective lens to be: 1. A microscope working in the air medium can have a max value of NA as 1. Hence the conventional diffraction limit is ~0.61λ. However, it is also possible to use immersion media to have NA greater than 1 because of its higher refractive index3.Imaging and microscopy have undoubtedly became an important tool in almost all fields of today’s technological world to see, visualize and analyze objects that are otherwise not seen by our naked eyes. Unfortunately, the lenses used in the optical microscope have a limit to the smallest resolvable feature. Before we talk about this limitation, it’s worth mentioning, how a lens forms an image of an object. An object scatters light at all angles due to diffraction. As the size of the object decreases the angle of diffracted light which carries the information about the object increases. So, while imaging smaller objects, conventional lens (due to limited aperture size) cannot collect all these light waves diffracted at a higher angle. Hence resulting in poor resolution of the image of the object. Ernst Abbe, in 1873, demonstrated that there is a limit to the resolution that a conventional lens can achieve and it is dependent on the wavelength of light, λ, and the numerical aperture , Stimulated emission depletion (STED) by use of a doughnut beam12 and fluorescence localization microscopy13. The SIM techniques help in retrieving the lost higher spatial frequency content in an image by shifting the frequency content using spatially modulated light followed by a post-processing step to retrieve the high-resolution image. However, the improvement in resolution is only about twice that of the traditional microscopes. Additionally, the post-processing steps are complicated and time-consuming. Non-linear methods like STED and fluorescence localization microscopy, however, require either fluorescence labeling or post-processing to achieve superresolution. Recently, the concept of superoscillation has emerged significantly in the context of far-field, label-free and non-contact superresolution imaging.Perhaps this fundamental limit has encouraged many researchers to come up with several techniques over the years to greatly enhance the resolution of optical microscope between tens and hundreds of nanometers. For instance, scanning near-field optical microscopy (SNOM) developed in 198415. Superoscillation in optics originated from the work of Torraldo di Francia in which he applied the concepts of super-directive antennas to an optical imaging system to see beyond the diffraction limit16. The idea of superoscillation was conceived and applied to many physical systems by Berry17. His works were mainly based on the work of Aharonov et al. on weak measurements in quantum systems18. Method for creation of optical superoscillation using a complex diffraction grating was proposed by Berry and Popescu19. Huang et al.20, demonstrated experimentally, for the first time, optical superoscillations by diffraction from a quasi-periodic array of nanoholes. Using superoscillatory techniques we can achieve a small spot which will be called from now as ‘hotspot’ which is less than the diffraction limit, while this is obtained at the expense of energy. In terms of optical superoscillations, a hotspot will always be accompanied by high-intensity side lobes which are higher in energy than the hotspot in the center.Superoscillation is a mathematical concept in which a band-limited function is capable of having a local component that can oscillate faster than it’s fastest Fourier componentet al. developed a new superoscillatory microscope. They developed and fabricated a binary phase mask consisting of concentric rings that are based on binary particle swarm algorithm21. Creation of super-oscillating (SO) beams with sub-diffraction limited features have been developed by modulating the lens’ pupil22 and by superposition of Bessel beams25. A super oscillatory function could also be constructed using a complete set of prolate spheroidal wavefunctions (PSWFs)26. The concept of design of annular pupil phase filters for the generation of superoscillation was proposed by Cagigal et al. in 200427. In 2017 Singh et al. developed a method using Spatial Light Modulator (SLM) for shaping the sub-diffraction hotspot obtained and using it to trap a single nano-particle28. In 2018, Rogers et al. with the use of PSWFs achieved simultaneously optimization of spot size and Field of view29. In 2019, Shapira et al. investigated methods to produce multi-lobe optical superoscillating beams, with nearly constant intensity and constant local frequency and successfully tested in structured illumination microscopy30.In 2012, Rogers CTF) shaping computed digitally in a computer by using virtual Fourier filtering without the need of using any complex mathematical functions or calculations. We also show that we are capable of tailoring different hotspot size with varying FOV. Specifically, those that match well the microscopy applications in which imaging of cells having a FOV being around 10–15 microns. We show through simulation, that indeed it is possible to go beyond the classical diffraction limit using our technique. As proof of our concept, we experimentally apply our technique on a digital lens that is being realized with a spatial light modulator (SLM) having Though the techniques described above are undoubtedly powerful in producing superoscillatory hotspots, most of them use strong mathematical calculations for the formulation of the phase mask that is needed for the creation of the hotspot or they use some sort of optimization algorithm to attain it. In our research, we propose a novel technique in which we design a phase mask which when applied to a lens can produce a superoscillatory spot. The main advantage of our technique is that we use a simple Coherent Transfer Function . In the frequency domain the corresponding spectra of Eq. CTF), u, v are the frequency coordinates. H can be described as:P is the pupil of the system, λ wavelength of the light used and zf the focal length of the imaging system. For a lens, the pupil function is a circular aperture given byw is the radius of the aperture of the lens. From Eqs. f0 is the cut off frequency of the CTF given by:zf is the focal length of the lens.Let us consider a coherent imaging system as shown in Figure 131. Hence using this technique, it is possible to engineer the psf of a lens34. In our technique, we use a modified GS algorithm to engineer the psf of the lens to obtain a hotspot. Before we discuss the modification, it’s worth mentioning the existing GS algorithm for psf shaping. The basic idea of psf shaping is to apply a phase mask in the lens pupil plane, such that the psf of the lens is shaped to the desired intensity profile. The advantage of this technique is that it is done digitally on a computer. Figure psf.Phase retrieval techniques like the Gerchberg-Saxton (GS) algorithm deal with the problem of obtaining the phase of a light field by just knowing the modulus of its Fourier transformCTF to obtain a new CTF denoted asThe algorithm starts with an assumption of a random phase mask with phase Hnew, which would yield the psf of the system corresponding to Hnew in the psf plane. In the following step, we preserve the phase of the psf and set the amplitude as our desired amplitude pattern. We then perform Fourier transform on the CTF plane. In the next step value of psf to the desired psf. The result is a phase mask with a phase psf. This is a very powerful technique to shape the psf. The requirement is to know the desired amplitude pattern beforehand. It is possible to construct a hotspot amplitude pattern mathematically and set it as desired psf amplitude to obtain the phase mask. However, the mathematical construction of such hotspots already yields the corresponding phase masks that produce such spots. Hence, there is no need to do such an iterative algorithm for obtaining the same. Also, mathematically it is hard to construct such hotspots.We then proceed to take the inverse Fourier transform of psf to a superoscillatory hotspot.Using our novel technique, we show that indeed without the prior knowledge of such mathematically formulated hotspot amplitudes, it is possible to create a phase mask that can produce hotspots with a small modification to the existing GS algorithm. Figure psf, we perform a virtual Fourier filtering of the psf using a filter mask. The filter mask has a circular region with a radius r1, and an annular region with an inner radius r2 and outer radius r3. The criteria for the selection of these radii will be discussed later in the simulation section. The mask takes the following functional value: and set amplitude as that of the mask (m). Hence the filtered psf can be written asIn the modified step, we multiply the virtual mask to the extracted phase of the psf will converge to a hotspot depending on the right choice of the filter mask. In the following section, we show how it can be done through MATLAB simulation.The remaining steps are the same. After several iterations, the nm) for a lens with the same NA . The initial step in the simulation is to set the pixel size of the psf plane L of the psf plane is given byM is the number of pixels in the x-direction. We have set M = 1024 pixels. Now we can formulate the CTF plane based on the psf plane. They both are related by a Fourier transform. Hence the pixel size of the CTF plane is given byIn the simulation, we show results for 3 different wavelengths  of the superoscillatory spot. FOV is measured between the two points on the side lobes as shown in Figure psf in this region to be zero. So larger the zero region between r1 and r2 is, the smaller will be the hotspot being produced. Hence, we have a tenability with regard to the size of the hotspot obtained. Also, by forcing the field at those points to be zero, the intensity is redistributed such that it forms a superoscillatory spot.Each mask takes about 100 iterations to yield a hotspot. In Fig. FOV and hence its applicability. Using the proposed technique, we could also increase the FOV by designing another filter mask such that we still obtain a hotspot with sufficiently good resolution below the diffraction limit and at the same time have an increased FOV.As previously mentioned, the hotspots are always accompanied by huge intense sidelobes which limit the This is because our filter design is such that between the hotspot and the main side lobe there is a minor side lobe whose peak intensity is smaller than the hotspot. We will now describe how to choose the value of the radii of such a mask that would produce a hotspot with increased FOV.r2 and r3 based on the second minor sidelobes. Value of r2 = 598.5 nm, where the amplitude drops to zero and r3 = 718.2 nm, where the amplitude then goes to a maximum. Now choosing of r1 will yield us a hotspot. We found that a hotspot is obtained when the value of r1 is such that the ratio between r1 and the point where the amplitude of the psf first drops to zeros (i.e. 325.8 nm) is less than 0.25, which means it can take values between FOV. The upper limit value will yield a hotspot with increased FOV. As the value of r1 is decreased from the upper limit we see that there would be an increase in the intensity of the minor sideband with respect to the hotspot which will destroy the FOV of the hotspot. We simulated the increased FOV for the case in which r1 is set to 79.8 nm and yields an increased FOV. Figure FOV of 1123.7 ± 6.65 nm with a hotspot size of 166.4 ± 6.65 nm very well below the diffraction limit. Now we can have an analysis of the intensity profile plots in Figure FOV from 498.7 ± 6.65 nm to 1123.7 ± 6.65 while keeping the increase in hotspot size considerably less from 153.1 nm to 166.4 nm. . We have kept the NA to be the same as the previous one. Figures NA. And we have seen that the criteria of selection of the mask parameters remain unchanged with wavelength and NA.Simulation is done for other wavelengths as well (mentclasspt{minimaCTF plane given by:CTF plane respectively. In our case Using our simulation (for μm pixel size) such that it produces a diffraction-limited spot corresponding to a lens of mm from the SLM in +1 or −1 diffraction order. Figure μm. Figure μm. SLM plane deviations and noise resulted in a larger spot than expected. Despite these aberrations, we were able to obtain the hotspot and its dimension is close to the one designed in simulations.In order to show the proof of concept experimentally, we programmed a lens phase function in a computer-generated hologram and displayed it on our Spatial Light Modulator (SLM, HoloEye, 1080 × 1920 pixels, 8 NA of 0.0075. We have already discussed the criteria for the selection of the virtual mask that we use to perform the Fourier filtering. We have used 1024 × 1024 pixels in simulation with a pixel size of the psf plane as 1 μm. We have used two masks for CTF shaping, mask 1 and mask 2 (Figure FWHM = 23 ± 1 μm and 25 ± 1 μm respectively. Figure CTF shaping. The obtained phase mask is encoded in a computer-generated off-axis hologram and is applied on the SLM which already has a hologram with the lens function. So, it will be equivalent to the case in which we are placing a phase mask in the pupil plane of the lens. Mask 1 has parameters of r1 = 12 μm, r2 = 44 μm and r3 = 59 μm. Mask 2 has parameters of r1 = 10 μm, r2 = 80 μm and r3 = 97 μm.The simulation was performed on a lens that is equivalent to an 2 Figure  that yieμm, we get ~25.6 ± 2.2 μm in the experiment (see Figure FOV of 66 μm in the experiment versus 71 μm in simulation. The intensity ratio between the maximum of the hotspot to that of the side lobes is equal to 0.52 in the experiment whereas in the simulation it is about 0.91. This deviation is probably due to the non-uniformity in the illumination. In Figure μm versus 25 ± 1 μm for the simulated hotspot.The experimental results are shown in Figure FOV of 150 μm between the central hotspot and the main bright sidelobe. There are minor sidelobes whose intensities are lower than the central hotspot. In the experiment, we get considerably similar results with an increased FOV of 154 μm. However, the intensity of the minor sidelobes in the experiment is not similar to that of the simulation. Still, they are almost equal or less than the central hotspot. The reason for this discrepancy can be attributed to the non-uniformity in illumination. The intensity ratio of the central spot to the main side lobes, in this case, is equal to 0.72 versus 0.87 in the experiment. Hence, we get an increased FOV with an increased Intensity ratio.In this case, the simulated hotspot shows an increased We have presented a novel technique for the generation and manipulation of superoscillatory hotspots. Our work brings the concept of CTF shaping to the superoscillatory research regime, which was not yet investigated before. The uniqueness of our method is that, we don’t use complex mathematics for the generation of a hotspot, rather our method produces hotspots of different sizes based on the tuning of the Fourier filter mask that we introduce in the digital optimization.In our work, we also showed the concept of increasing the FOV with a considerable intensity ratio with the hotspot to sidelobe and less loss in resolution of the generated hotspot. We hope that our technique will become an important tool in a range of applications and initiate other scientific researches using this tool.Supplementary information.


Sir,et al. [One of the important preliminary tasks for formulating epidemic control programme interventions is the identifications of clusters that drive an epidemic in a population. Information about seroprevalence within various groups in the population is often one of the critical requirements for clustering in epidemiological studies. The article by Trickey et al.   with n number of vertices and m number of edges. Each vertex represents an individual in the injection-sharing network, and the number of edges in the network is the individuals that share injections among them. Two vertices corresponding to two individuals are connected by an edge if, and only if, they share an injection; the arrow can also indicate if the sharing is a two-way process or one-way process if the data are available to make this a directed graph. Using algorithms to match the patterns within the finite graph constructed, one could provide useful information on drivers and clusters of the spread of epidemics, such as hepatitis C, HIV, etc. Such information will be indispensable in formulating effective epidemic control programmes and targeted interventions. The network methods developed by us in the course of our analysis of the spread of parasites [et al. [Even if we assume that the survey data  and corrarasites , 4 have  [et al. .Gi  be the ith subgraph with the pi number of vertices and mi number of edges formed from a subset of vertices of G  for i = 1, 2, …, k such that pi is associated with the information on the presence or absence of pre-determined attributes that were collected during the population-based serosurvey. pi. The attribute information stored at each vertex could help provide the qualitative features of selecting a partner or being selected by a partner to share injection. The graph G  and its set of all subgraphs Gi  for i = 1, 2, …, k will have complete information on attributes and seroprevalence information that was collected through a serosurvey.The originality that we would like to bring into this graph structure is to store attribute-level information at each vertex. Let G1 and G2 are constructed based on two population surveys, then isomorphism of these two graphs means there is a 1-1 correspondence between the vertices of G1 and G2. Such identification can be achieved through efficient matching algorithms. One such example can be found in Bonnici et al. [Once the population network structures are formed and vertices of transmission dynamics within this network are identified, then either the complete network structure formed or subgraphs can be used to identify similar structures or subgraphs in populations where network information is available but not the status of seropositivity. This identification is similar to the subgraph isomorphism problem in graph theory, which can be summarised as follows: suppose two graphs i et al.  for matcRegression models are powerful statistical tools but they could at most give an average sense of the attributes in


The characteristics of removable magnetostrictive thin patches are investigated for the generation of guided waves in plates. The directivity patterns of SH, S0 and A0 modes have been measured in a thin metallic plate for different combinations of static and dynamic magnetic field directions. This used different coil geometries such as racetrack and spiral coils to generate the dynamic magnetic field, as well as separate biasing static magnetic fields from permanent magnets. This arrangement generated signals via both Lorentz and magnetostrictive forces, and the resultant emitted guided waves were studied for different dynamic and static magnetic field directions and magnitudes. It is demonstrated that different guided wave modes can be produced by controlling these parameters. Non-Destructive Testing (NDT) techniques are widely used for the inspection of different structures in numerous industrial applications. Guided Waves (GWs) are among these techniques and they are widely used in different applications such as the inspection of pipes ,2, railsGWs can be generated using various transduction mechanisms such as piezoelectric transducers and Electro-Magnetic Acoustic Transducers (EMATs). The latter are attracting more industrial interest as they are contact-free transducers and do not need any couplant to operate on metal surfaces. The main transduction mechanism for EMATs is the Lorentz force, although magnetostriction can sometimes play a part, for example on corroded steel ,13. By rTo deal with the efficiency of EMATs, and to overcome some of the limitations of air-coupled systems, this paper investigates the use of removable magnetostrictive patches that are attached to the surface of the specimen. While magnetostrictive patch transducers (MPTs) have been reported in the literature ,20, thisλ, and is defined as the ratio of the ratio of the fractional change in length δl over the initial length 0lMagnetostriction can be defined as the change in the dimensions of a sample when an external magnetic field is applied. It was first discovered by Joule , and occH) and λ, as illustrated in sH is selected so the generated strain is created at some bias point (I), such as that shown in dH) then causes the resultant change in dimensions.In the absence of an applied magnetic field, the different magnetic domains are orientated in such a way as to minimise the total magnetization of the sample . If a suλ–H curve causes linear oscillation around the bias point, providing the highest strain change for a given field change. The process of selecting the biasing magnetic field and the oscillating dynamic field is of importance, as a linear response is required when magnetostrictive patch transducers are used to generate guided waves [When a dynamic magnetic field is applied, the ed waves ,32. Thised waves ,36,37,38Magnetostrictive Patch Transducers (MPTs)  can be uWhile MPTs have been reported previously in the literature, earlier papers did not present detailed characteristics such as guided wave directivity patterns for different configurations of both dynamic and magnetic fields. The work described in this paper provides experimental measurements of the characteristics of guided waves when generated by a removable magnetostrictive patch. This is studied for various conditions of coil and magnet geometries, including one where the contribution from the Lorentz mechanism is minimised by careful choice of the orientation of dynamic and static magnetic fields.Two sets of experiments were performed. The first was to study vibrational patterns directly underneath the removable patches, while the second measured the directivity patterns of SH, S0 and A0 modes at some distance from the patch.These initial experiments were designed to investigate the vibrational characteristics of the region within a 3 mm thick glass plate that was directly below a thin magnetostrictive patch when subject to different dynamic and static magnetic fields. The patch was adhered to the plate surface using a thin layer of double-sided tape and could be removed after a particular measurement without damaging the surface of the sample. These first experiments were conducted using a glass plate, as this was known to be isotropic and non-conducting and have low acoustic attenuation properties over the frequency range of interest. The lack of electrical conductivity was felt to be important, as the presence of conductivity might have affected the Lorentz forces that would also be generated within the MPTs in some configurations.®VACUUMSCHMELZE GmbH & Co., Hanau, Germany) with a saturation magnetization of 2.35 T and high permeability value of up to 18,000 N A−2. The mechanical and magnetic properties of the VACOFLUX iron-cobalt alloy are given in A schematic diagram of the experimental configuration used for this type of measurement is presented in An 80 × 80 mm square patch of 55 µm thickness was attached at the centre of the glass plate of dimensions 200 × 200 mm. On the other side of the glass plate, and directly under the patch, a reflective tape was attached in order to reflect light back to a vibrometer, used to detect the vibrations of ultrasonic waves that existed directly under the MPT. A PSV-400 3D vibrometer laser scanner within the vibrometer setup was placed parallel to the glass plate at a distance of 1.2 m. The laser head is constructed with three laser beams within a single vibrometer head. They detect vibrations both in-plane and out-of-plane. Each beam is responsible for measuring the vibration in a different direction . The distance was selected in order to obtain an optimal reading from the laser beam while keeping a good scanning resolution. The scanning heads of the PSV-400 system were positioned so as to directly observe the vibrations of the patch after excitation.In order to stimulate the magnetostrictive patch to generate GWs, either a racetrack coil or a pancake coil were connected to a high-power pulsing unit. The current waveform that was input to the racetrack coil consisted of a one-cycle sine wave of 120 kHz central frequency . The opesB) and a coil to provide the dynamic magnetic field (dB). The racetrack coil shown in sB was generated using a U-shape alnico permanent magnet  and dB (generated by the coil) for two coil geometries. Note that this was likely to be very different from a standard EMAT using Lorentz forces only, as a substantial magnetostrictive component would be expected, whose magnitude and direction of operation had to be determined. For these reasons, Configurations 1 and 2 have two measurements where the coils/magnet orientation was fixed, but where the whole arrangement could be rotated by 90° with respect to the patch. This would identify any directional effects or anisotropy caused by the patch itself. The four configurations are illustrated more fully in sB but with the pancake coil in-plane; this configuration would thus be expected to generate both Lorentz and magnetostrictive forces, which would act radially. Conversely, Configuration 4 used an in-plane magnetic field, which would be expected to create a more complicated set of forces normal to the patch via Lorentz forces, as shown.Configuration 3 had an out-of-plane The second set of experiments investigated the signals that would be generated by the magnetostrictive patch attached to a metallic sample. The experimental arrangement is shown in 2, and the patch thickness was 55 µm. In these experiments, the coil was a racetrack printed circuit coil of 0.035 mm thickness. The printed coil was insulated from the magnetostrictive patch using a 0.1 mm thick adhesive plastic film. The width of the single track of racetrack coil was 1 mm and the spacing between tracks was equal to 0.5 mm. The coil was formed of 10 turns and it was printed on a single layer of the printed circuit board (PCB). The full coil track width was 14.5 mm, and the PCB substrate was 1.57 mm thick. The permanent magnet was placed on the straight region of the racetrack coil, as previously shown in The magnetostrictive patch was attached to a 3 mm thick, non-magnetic metallic plate for these guided-wave propagation experiments. The size of the square iron cobalt alloy patch was 76 × 76 mmFor this set of experiments, the detection system consisted of a 3D laser vibrometer mounted on a three-axis arm. The laser head contained three laser beams. The beams are separate 3 Doppler vibrometers providing measurement in the three-axis system for the back scattered light. The optical sensors with the different beams can detect and measure the vibration in the in-plane and the out-of-plane directions. The motion of the laser beam was designed to perform a 360° rotational motion with a 10° angle step so as to capture the waveforms at different angles. The laser beam head was positioned as shown in Different configurations for the static and dynamic magnetic fields acting on the patch were tested. As before, The results of experiments involving both scanning the area under the patch on a glass plate and measuring directivity patterns of GWs at some distance away in a metallic plate are presented in this section. The aim was to show both how the patch vibrated, and how the guided wave modes were generated by the different dynamic and static field configurations.sB) and dynamic (dB) fields along the X and Y directions, respectively, with the linear part of the racetrack coil aligned with the X direction. No Lorentz force was expected, as sB was parallel to the coil direction. The observations for both configurations thus show the contribution of the magnetostriction forces to the generation of the elastic waves. The distribution of vibrations within the patch at both the beginning and end of the signal are presented in xA, yA and zA, respectively. The overall amplitude of surface vibration at any particular location could then be calculated as the Modulus using the equationConfiguration 1 had the in-plane static  plane. Thus, for SH0 and S0 GW modes, the Lorentz force would be expected to be of less importance in tems of elastic wave generation. However, this arrangement would be expected to favour SH0 mode amplitudes, as the forces would be all in the X direction, and propagation appears to be predominantly in the Y direction.The next configuration was designed to set both the dynamic and static fields in the same X direction, as illustrated in Configuration 3 consisted of a permanent magnet, which provided an out-of-plane static magnetic field and a pancake-shaped coil in order to generate an in-plane dynamic field in all radial directions see . For thidB and sB).Configuration 4 consisted of the U-shape Alnico magnet that was used to generate a static magnetic field along the X direction and a circular coil generating a dynamic radial in-plane field. The results for Configuration 4 are shown in Configuration 4 creates a more complex Lorentz force behaviour. The configurations consist of a linear static magnetic field combined with a circular distribution of dynamic magnetic field and hence a circular distribution of the current vector. This non-uniformity results in Lorentz forces generated along the Z axis with a non-uniform magnitude. The energy generated at early time delays is concentrated in a central location where the Lorentz forces are expected to be minimal . The GWs are radiated primarily in the Y direction.dB and sB for a given coil geometry. For such a plate, the expected dispersion curves are shown in The next set of experiments were designed to capture GW waveforms as a function of propagation direction once they had propagated a certain distance from the patch. The sample chosen was a 3 mm thick, non-magnetic metallic stainless-steel plate. The aim was to look at the directivities of S0-, SH0- and A0-guided wave modes, these being the three modes allowed in the thin plate for the frequencies of interest. The aim was to see how they were affected by the relative directions of The directivity results obtained for the S0 and SH0 modes are shown in Y-axis (at 0° and 180°). This is expected, as Bs is acting along the X-axis, favouring SH0 generation, noting that initial radiation along this axis was observed earlier to be initiated in the image of X-axis, favouring the generation of shear motion leading to the SH0 mode). The S0 has a quadrapolar directivity of smaller amplitude overall, but with lobes rotated with respect to the SH0 mode.First consider It was observed in the directivity measurements of To illustrate the types of waveforms detected, examples for Configurations 1–4 are presented in The amplitude of the A0 mode is lower in all the cases illustrated in sB and dB fields in the X-Y plane. With no Lorentz force expected, the motion of the patch would be due to magnetostriction effects only. The result was an initial asymmetric wave motion, visualised over the patch, which then led to a complicated directivity pattern for both S0 and SH0 modes. In contrast to this, the A0 mode directivity contained prominent lobes along the 35°–215° and 320°–140° axes. Configuration 1 shows that using magnetostriction forces only to generate guided waves is a complex phenomenon. A full understanding of the underlying complex generation mechanisms at work is outside the scope of this experimental study, and would require modelling of both the interaction between static and dynamic fields and the subsequent guide wave generation from the resultant induced stresses on a particular sample.It is evident that some interesting interactions are taking place within the magnetostrictive patch when attached to a plate. Configuration 1 created orthogonal Configuration 2 also led to a complicated S0 and SH0 behaviour. However, this configuration could be used to optimise A0 mode generation, while noting that observed amplitudes were smaller than those of the SH0 and S0 modes, whose arrivals can still be observed on waveforms see b. The A0In Configuration 3, both Lorentz and magnetostrictive forces were generated in the XY plane. The radiation patterns of A0, S0 and SH0 are all fairly uniform across all angles, as would be expected from the cylindrical geometry of the excitation fields.sB. Thus, this configuration could be used if this mode only is of interest in a particular direction. The A0 mode was generated with a fairly low amplitude and this is due the fact that the A0 mode requires some component of out-of-plane motion  which was not favoured in this configuration. The Lorentz forces in theory would be minimal in the 0° and 180° and start to gradually increase toward the 90° and 270°. This can be observed through the polar radiation of the A0 mode, where it is minimal in 0° and 180°.Configuration 4 demonstrated that magnetostrictive effects led to a dominant SH0 mode in the expected X direction (0°) direction, due to the orientation of the static field It should be noted that the measurements were taken using the laser system around 360° without interpolation between measurement points. Note also that the directivity patterns measured for different wave modes in The use of a vibrometer detector has been shown to allow the characteristics of guided waves generated by removable magnetostrictive patches to be measured for the first time, and some interesting phenomena were observed. It has been demonstrated that these devices can be used to generate S0-, A0- and SH0-guided wave modes with the provision of control capability in terms of directivity and relative amplitude of the three GW modes investigated. The relative amplitude and direction of each of these modes can be altered by changing the dynamic and static magnetic field distributions within the patch, and this has been achieved by using different combinations of dynamic coil shapes and static magnetic field directions. It is evident from the data that there is a complicated interaction between the relative directions of static and magnetic fields and the patch, and that this arises because both Lorentz and magnetostriction forces could be generated, depending on the exact geometry chosen. This interaction is obviously complex, and hence careful selection of the direction of the dynamic and static magnetic fields should be adopted in order to favour specific modes compared to others. A fuller understanding and modelling of the generation mechanisms, and their effect on the resultant guided wave mode properties, is the subject of current research. However, such transducers are likely to find applications in many areas where ultrasonic guided waves are useful, especially in non-destructive evaluation measurements. The ability to adjust the excitation conditions so as to change both the guided wave directivity and the dominant mode for a given patch, simply by changing the magnetic field conditions, will provide great flexibility in such measurements.The work reported in this paper shows that by adopting such an approach, a particular guided wave mode can be generated in a particular direction with the optimum signal level. This is of advantage in certain measurements where a particular mode is required . Conversely, configuration 3 provides a fairly uniform radiation pattern for both the S0 and SH0 modes. Once the patch has been attached to the surface, the amplitude of each of the three modes can be adjusted simply by altering the coil and/or magnet geometry, giving great flexibility—a different patch need not be used on the surface. It was shown that the A0 mode is the least favoured by the technique, due to the fact that it requires a large out-of-plane component to be generated efficiently.


Epilepsy is one of the most common neurological disorders . Many individuals continue to have seizures despite medical and surgical treatments, suggesting adjunctive management strategies are required. Promising effects of daily listening to Mozart on reducing seizure frequency in individuals with epilepsy have been demonstrated over the last 20 years, but not in a rigorously controlled manner. In this study, we compared the effect on seizure frequency of daily listening to either Mozart K.448 or a spectrally similar, yet non‐rhythmic control piece. We hypothesized that there would be no difference in seizure counts when participants listened to Mozart K.448 vs when they listened to the control piece.We employed a randomized crossover design, in which each participant was exposed to both three months of daily listening to the first six minutes of Sonata for two pianos in D major by Mozart  and three months of daily listening to phase‐scrambled version (control period). There was a three‐month baseline and a three‐month follow‐up period before and after the six‐month listening period, respectively. Change in seizure counts obtained from the seizure diaries was considered as the main study outcome.t test, estimation statistics and plots, and Cohen's d), our results revealed a reduction in seizure counts during the treatment period, which was not observed for the control period .Using three methodologies to investigate the existence of the treatment effect (paired Using a spectrally similar control piece, our study advances previous reports that were limited by a “no music” control condition. Daily listening to Mozart K.448 was associated with reducing seizure frequency in adult individuals with epilepsy. These results suggest that daily Mozart listening may be considered as an adjunctive therapeutic option to reduce seizure burden in individuals with epilepsy. Many individuals with epilepsy continue to have seizures despite medical and surgical treatments, suggesting a need for adjunctive management options.The promising effect of daily listening to Mozart in individuals with epilepsy has been reported for the past 20 years.The effect of daily exposure to Mozart K.448 (treatment piece) was compared with a phase‐scrambled version with no rhythmicity (control piece).Using a spectrally similar control piece, our study contrasted with previous reports that were limited by a “no music/sound” control condition.Our results revealed a reduction in seizures during the period of daily Mozart K.448 listening, an effect not observed for the control piece.1Epilepsy is considered the most common serious neurological disorder in the world characterized by the recurrence of seizures, and affecting more than 50 million people worldwide.Previous neurophysiological and clinical studies have demonstrated that the use of different direct —due to its ubiquity in the epilepsy literature.In this work, we have explored the effects of daily listening to two different auditory stimuli on seizure frequency in adult individuals with epilepsy using a crossover study design, where each individual was exposed to both treatment and control auditory stimuli, serving as their own control. Mozart K.448 was chosen as the treatment piece22.1The study protocol was approved by the University Health Network Research Ethics Board. Prior to starting the intervention, informed consent was obtained from all participants. The participants were chosen from a pool of adult individuals with epilepsy who were previously admitted to the Toronto Western Hospital (TWH) epilepsy monitoring unit and who had undergone either scalp or intracranial electroencephalography (EEG) recordings as part of a diagnostic of presurgical workup.2.2The treatment stimulus was the first six minutes and a half of the first movement of Mozart Sonata for two pianos in D major or Mozart K.448, performed by Alicia De Larrocha and André Previn. We chose the first movement of the sonata given the positive effects of the first movement2.3© to assign participants to two groups. The individuals in group A started the intervention by listening to the treatment stimulus—Mozart K.448—once a day for a total period of three months (treatment period) and switched to listening to the control piece once a day for the following three months (control period). Individuals in group B engaged in identical listening regimens. However, they started with the control piece, followed by Mozart K.448. Additionally, there were three‐month baseline and three‐month follow‐up periods before and after the six‐month listening period. The information regarding participants previous musical history is presented in Figure The randomized control research study employed a crossover design by using a computer‐generated algorithm written in MATLAB2.4Since not all of the individuals with epilepsy were able to classify and differentiate seizure types and auras using common scientific terms, we instructed the participants to discuss with us the different and personal ways they classify their seizure type(s) using their own words. The participants were then advised to record their seizures in their seizure diaries, using their own symbols to label them differently, notably in the event of auras or multiple types of seizures. Adding the participants self‐reported diary next to the existing notes from their neurologist and the previously available history of the EEG findings describing their seizure type(s), the seizure diary entries served as the primary outcome of the study. During the study visits to the hospital, seizure diaries were obtained from participants after each three‐month period   and per‐protocol (PP) analysis. For the ITT analysis, missing observations due to dropouts were handled by the last observation carried forward (LOCF) method, using the last observation of an individual's seizure counts before dropout of the rest of the intervention. The total numbers of seizures during the treatment and control periods were considered as paired observations for each individual and were normalized with respect to the individual's total number of seizures during the baseline period. Shapiro‐Wilk test was used to check the normality of the dataset, using the Python statistical functions module.t test considering the normal distribution of the dataset,d. In addition to providing the P‐value, we also focused on the magnitude of the observed effect size and its’ precision using estimation statistics and plots,mean ”.The effect size was analyzed using three different methods: the paired Student's 3rs = .155, P‐value = .15) or during the control period .The study group involved 13 adult individuals with epilepsy , between 26 and 75 years of age with a mean age of 45.8 years, and an average of 2.3 AEDs per individual  withdrew from the study after finishing the treatment period and during the control period; both belonged to group A (treatment‐control sequence). One individual from group A became seizure‐free during the treatment period . The post‐listening effect of listening to the treatment piece was addressed during the follow‐up periods. Individuals in groups A (control‐treatment sequence) and B (treatment‐control sequence) showed 18% and 24% increase on their average normalized seizure counts during the follow‐up period, respectively . Individuals with normal and abnormal MRI demonstrated no significant difference between their seizure counts , suggesting both groups of patients benefit similarly from listening to Mozart. In summary, individuals demonstrated a 35% reduction in their seizure counts on average while listening daily to Mozart K.448 for three months compared to daily listening to a spectrally identical (non‐rhythmic) control piece.Statistical analysis revealed the existence of a treatment effect. Under both ITT and PP analysis, individuals in group A (treatment‐control sequence) showed slightly larger treatment effect  than those in group B (control‐treatment sequence). For individuals in both groups A and B, the mean seizure count was reduced during the treatment period as compared to the control period under ITT  and PP analysis . The results of paired Student's 4In this study, we investigated the effects of daily listening to two different auditory stimuli on seizure counts in adult individuals with epilepsy. We employed the first 6 minutes of Mozart K.448 as our treatment piece and a control stimulus with the same power spectrum to that of the Mozart piece, but shuffled in phase, rendering it non‐rhythmic. We hypothesized that there would be no difference in individual seizure counts during the period of daily listening to the treatment stimulus in comparison with the period of daily listening to the control stimulus. Using different methodologies to estimate effects size, our results revealed a reduction in seizure counts during the period of daily listening to Mozart, which was not observed for the control stimulus Table . All parAdditionally, by estimating the compliance rate during the treatment and control periods, we assessed how scrupulously our participants followed the intervention. The high compliance rate during both control and treatment periods  is notable. No information was provided to the participants during their enrollment in the study to bias or direct them toward believing which stimulus might be more likely to have a positive effect. However, it should be noted that the potential positive effects of listening to Mozart have been mentioned in the media over the past 15 years and it would be naive to assume that participants were necessarily blinded to the effects of the employed auditory stimuli not only in this study, but also as a burgeoning topic for other studies.We found the high compliance rates during both treatment and control periods to support the findings of a recent survey among 40 individuals with epilepsy in the United States, which revealed that 75% of participants were interested in listening to specific music on their mobile phones in order to reduce their seizure frequency.There are many environmental factors that could also affect seizure counts in individuals with epilepsy, such as lack of sleep and varying levels of both physical and mental stress. Considering the length of our intervention, we cannot comment on how changes in such environmental factors may have impacted the observed effect across our participants. Our results are similar to those reported by Hughes and colleagues,Our study design and protocol differed from previous clinical studies, which primarily used a parallel designIn terms of the existence of a general treatment effect during the period of listening to Mozart K.448, we found our results in agreement with the only other randomized control study available on adult individuals with epilepsy—which involved 36 individuals—notwithstanding a number of differences between the two protocols used and the intervention design.All of our participants, except the two outliers from groups A and B (P12 and P09 in Figure The exact neural mechanisms underlying reducing seizures by listening to music have not been determined yet. The potential theories on the effect of listening to music on central nervous system have been discussed in detail in a number of the previous review work.As with other experimental work, this study comes with its own limitations. Considering the size of our study population and that variability exists between individuals, our study might have benefitted from a larger sample size. However, our use of a crossover design permitted us to draw statistical inferences from a smaller sample size than would be required for a parallel design while achieving the same type I and type II errors.One of the most significant challenges of studies with crossover designs is the existence of the carry‐over effect.None of the authors have any conflict of interest to disclose. We confirm that we have read the Journal's position on issues involved in ethical publication and affirm that this report is consistent with those guidelines.Supplementary MaterialClick here for additional data file.


Mendeley DataWater quality depends on many factors. Some of them are essential for maintaining the minimum sustainability of water. Because of the great dependence of fishes on the condition of the aquatic environment, the water quality can directly affect their activity. Therefore monitoring water quality is a very important issue to consider, especially in the fish farming industry. In this paper a digital fish farm monitoring system is introduced and a collection of experimental data of water quality monitoring was presented, which were directly collected from a fish pond. As the quality factor of water affects its aquatic life form sustainability, therefore the quality factors of the water were measured using digital sensors. Temperature, pH factor and Turbidity were selected as the basic quality factors to measure. The dataset contains data recorded from two different water levels to analyze the aquatic environment more efficiently. Each level has 9623 sets of data of the selected parameters. Collection was continued all day long for several days. Later collected sensor data were analyzed as short period time series to find its properties. Machine Learning regression method was used to predict near future conditions. Moreover data were processed to find any repetitive patterns in its properties. This dataset represents the exact condition of the environment of the fish pond. Therefore it can be used to develop a system to monitor fish farms digitally. Using these data in machine learning, predicting the future is possible for advance monitoring of a fish farm. The dataset is available in  Moreover, training machine learning regression method with it will help us to forecast the aquatic environment in the near future. Also any anomaly can be detected very quickly in the water quality factors by using the machine learning process. Automatic fish farm monitoring will be possible with it •This dataset will be beneficial for the fish farming industry. It will be also beneficial for environmental scientists as it contains raw natural data.•Further these data can also be used for analyzing local geographical characteristics and discover new scopes of farming.•If such a data collection system is to be implemented in every fish farm throughout the country, a central monitoring and data base system can be built. It will help to compute the overall fish production in the country and help to make statistics of national profit, net productions, laggings, type of productions, possible productions, lag of any productions and many more.1The dataset presented in this article is available in the Mendeley data repository Day and night time has different levels of temperature and pH rating and changes at a different rate. Temperature increases at the day time and decreases at the night time, where most of the time pH also has a tendency to increase at day time and slowly decrease at night time. Turbidity does not affect much by the day night cycle. With the increase of water depth temperature changes at a very slower rate. As a result the effect of day and night cycle is comparatively lower in the sensors 60 cm underwater. Temperature and turbidity values are not the same for both 30 cm and 60 cm levels. These two levels have difference in sensors values. Temperature increases with the depth of water level. As a result temperature rating in 60 cm underwater is warmer than 30 cm underwater. On the other hand turbidity level in 60 cm underwater is much lower than 30 cm underwater. Furthermore the rate of change of parameters are not the same for both water levels also. The experiment was conducted for seven days and among them there was a rainy day. In 2Before developing the system's algorithm identifying the most important water quality factors is necessary. Factors that affect water quality the most are needed to be monitored. Hence several quality factors were analyzed that have the maximum impact in the aquatic environment of a fish farm ,4. Based2.12.1.1Water quality greatly depends on the pH factor, whether the water is acidic or nonacidic. Different fish like different kinds of pH conditions. So depending on which type of fish is being cultivated in the farm the pH factor can be observed to calculate the water suitability. Cellular membranes of a fish get damaged in high pH level like 9–14. Where low pH levels affects the rocks in the sediment resulting in release of metals. This increases water turbidity. Therefore a pH meter was used to collect the pH rating of the water.2.1.2Maximum fresh water fishes have cold blood. That means they collect temperature from their surrounding water, thus synchronizing with the water temperature. Cold blooded animals are affected directly by its surrounding medium temperature. Temperature mainly affects their metabolism 2.1.3If there is a lot of suspended material in the water or an excessive amount of food it may make the water dirty. Moreover high turbidity because of algae present in the water can harm fishes. Such as Trichodiniasis is a disease that happens due to parasites. Also turbidity affects the growth of fish eggs and larvae 2.1.4To maintain the sensors, collect and store the data an Arduino Mega microcontroller board was used in this project. This board has enough input and output pin and processing power to support all the modules perfectly. To store data in the cloud storage an ESP8266 Wi-Fi Module was used. And to store data in an electronic storage device a micro sd card reader module was used.2.2In the fish pond total number of deployed sensors were five divided into two sets. The first set includes a Temperature sensor, a pH sensor and a Turbidity sensor. This set of sensors were 30 cm underwater from the water surface. A second set of sensors were used in a different depth. Because the temperature and turbidity rating in water changes with respect to depth. The second set includes a Temperature sensor and a Turbidity sensor. This set was 60 cm underwater from the water surface. Both sets had the same horizontal alignment yet different depth. The sensors were immersed in the water where the microcontroller and the other modules were above the water surface attached to a floating structure. The microcontroller board read data from the sensors all together. Then uploaded the data in the cloud database and stored in the storage device. Rate of data record on average was one set of data per minute. Later data was presented in a dedicated website for monitoring them from anywhere. For portable monitoring a mobile application had been developed. The website and the mobile application shows real time conditions of the water at any time. The mobile application is capable of notifying the user when any one of the parameters of the water quality factor crosses the safety limit. The overall data collection and storing system is presented in •Step 1: Delay 30 seconds for calibration of the sensors.•X and Y from the Temperature sensors.Step 2: Read data •Z from the pH sensor.Step 3: Read data •P and Q from the Turbidity sensors.Step 4: Read data •X, Y, P, Q and Z in the electronic storage device.Step 5: Write the data •Step 6: Delay 200 ms.•Step 7: Try to establish connection with the web host.•Step 8: If connection is established go to Step 9, else go back to step 7.•Step 9: Upload data in the database.•Step 10: Delay 300 ms.•Step 11: Go back to Step 2.Algorithm I: Algorithm for collecting and storing the sensor data2.3Data were presented in a dedicated website for monitoring the farm condition from anywhere and anytime. The cloud data collection and presentation system is shown in 2.4Machine learning regression method was used to predict near future data and compare them with the true data. For this purpose we used the Gaussian kernel of Support Vector Machine (SVM) learning model. 70% of the data was used to train the regression model and 30% was used to test it. Later prediction error was calculated by subtracting the predicted data from the true data.Matlab's script command “fitrsvm” was used to train and test the SVM regression model. The script functions used for fitting is given below:2.52.5.1Not applicable.The authors declare that they have no known competing financial interests or personal relationships which have, or could be perceived to have, influenced the work reported in this article.