To assess if Dutch children with Autism Spectrum Disorder (ASD) regularly visit a dentist and to evaluate parent’s satisfaction on the care provided.U tests (α = 5%).Parents of ASD children (2–18 years) were invited to fill out a survey. The survey consisted of questions regarding ASD severity, frequency of dental visits, history of dental pain, type of dental practice and parents’ satisfaction. Results were analysed using Chi square and Mann–Whitney p > 0.05). The children of unsatisfied parents reported more often pain during the last year (p = 0.013) and had a more severe type of ASD (p = 0.016).Of the 246 returned questionnaires, 19 were excluded (incomplete or unconfirmed ASD diagnosis). All children visited a dentist at least once and 5% of them had their last visit more than 12 months ago. According to parents, 15% of the children did not receive the needed care when they had toothache and 21% of the parents were unsatisfied with the current dental care provided. No difference was found between satisfied and unsatisfied parents in type of dental practice visited (The majority of Dutch ASD children investigated regularly visit a dentist and 21% of the parents is unsatisfied with the dental care provided. There is an absence of research on the prevalence of Autism Spectrum Disorder (ASD) for the Dutch population. International research estimates the prevalence around 1% of the world population and the Dutch National Health Council assumes that the prevalence in the Netherlands to be the same. Following this assumption; there are approximately 160.000 people in the Netherlands with ASD  health care systems are differently organised. For example, costs of dental care or insurance have been cited as core barriers to dental care in USA and China. This does not count for the Dutch situation, due to the provision of free dental care for children up to 18 years. Furthermore, in the Netherlands, ASD children have the opportunity to go to different types of dental practices, i.e., the general dental practice, the pediatric referral dentist or the special dental care centre, often situated in a hospital setting. To be eligible for treatment in a pediatric referral clinic or special dental care centre, children need to be referred by, for example, a general dental practitioner, general practitioner or pediatrician. Although these factors could implicate that oral health care for ASD children is sufficiently covered in the Netherlands, no details are known and consequently no objective comparison to other countries can be made to evaluate if the current system is enough for the needs of ASD children. Therefore, the aim of this study is to examine if Dutch children with ASD regularly visit a dentist and to evaluate the satisfaction of their parents on the dental care provided.The Medical Ethical Committee of the Vrije Universiteit Amsterdam declared that, according to the WMO , ethical approval was not needed.The sample comprised of parents/caregivers of children between 2 and 18 years with an ASD diagnosis who live in the Netherlands and who were willing to participate in this study. If parents had more children diagnosed with ASD, the survey had to be filled out considering the eldest child.www.nva.nl), Autisme Paspoort (www.autismepaspoort.nl) and Autism friendly dentistry (www.autismevriendelijketandheelkunde.nl). All three communities referred to the survey in their digital newsletter, and the final two also placed the invitation on their Facebook page. The digital survey could be filled out via a link to Surveymonkey. As these were all free accessible websites with an unknown number of visitors that met the inclusion criteria, the response rate cannot be determined. This digital survey was accessible from November 2015 to February 2016. During the congress of the Dutch Association for Autism in November 2015, in the city of Utrecht, the Netherlands, parents and caregivers of children with ASD were invited face to face to fill out a paper version of the survey. The survey was filled out anonymously. There might be an overlap in parents visiting more than 1 available sites . Therefore, in the consent letter parents were asked to fill out the survey maximum once.The invitation for filling out the survey was distributed through the websites of several ASD-communities, i.e., the Dutch Association for Autism  had previous experience with a dentist. For 81% of the respondent ASD children, the last dental visit took place in the last 6 months. For 14% of them, the last dental visit was 6–12 months ago and for 5% of the children it was between 1 and 3 years ago. Only one child had his dental visit more than 3 years ago. Dental visit features for the parents of the respondent ASD children are: all of them reported to have experience with a dentist. Eighty-five percent of the parents had their last dental visit less than 6 months ago, 14% between 6 months and 1 year, 1% between 1 and 3 years and in 1% of the parents the last dental visit was more than 3 years ago.All children (N = 81) were found to be equally distributed between referral dental practices and general dental practice (p > 0.05). These children are also found to be significantly more often difficult to brush . Furthermore, for children with severe type of ASD, the perceived cooperation in the dental chair is significantly worse, compared to that of children with the moderate or mild types of ASD .Regarding the oral hygiene, 49% of the parents found it difficult to brush their child’s teeth. Brushing frequency was for 4% of the children only 0–3 times per week, 22% brushed once a day, 23% brushed 8–11 times per week, and half of the children had their teeth brushed twice a day. Additionally, the children with severe type of ASD . Also, satisfied parents rated the cooperation of their child in the dental office higher (p = 0.001) and the perceived dental health status of their child was better than the rate of dissatisfied parents (p < 0.001), indicated by the Mann–Whitney U test. Additionally, the parents who were not satisfied with the dental care their child currently receive, were parents whose child more often had a toothache during the last year , had more often a severe type of ASD  and did not visit a dentist for more than 1 year (p < 0.001). The satisfaction of the parents is not related to the type of dental practice their child visited (p > 0.05), nor to the gender of the child  and is not related to the child having a complementary diagnosis or not .From the answers given to the posed questions, 21% of the parents is not satisfied with the dental care their child receives. The parents who were satisfied with the dental care provided to their child, were less likely to have problems with brushing their child’s teeth, compared to the dissatisfied parents , in comparison to the patients from a pediatric referral clinic or a general dental practice. Not visiting a dentist more than 1 year was not related to the gender of the child , nor to the severity of ASD . Remarkably, all children that had their last dental visit more than 1 year ago (n = 13), had a parent whose last dental visit was less than 1 year ago.When the child with ASD visited a special dental care center for his/her dental care, the chance for not visiting a dentist more than 1 year was significantly lower . Furthermore, not receiving the needed dental care was not related to gender  nor to the severity of ASD . These children were significantly more often patients in a general dental practice  compared to the special dental care center and pediatric referral clinic.The parents who answered that they could not find appropriate dental care when their child had a toothache, were parents of children who did not visit a dentist for more than 1 year  when compared to USA (71–88%) and China (75%) (McKinney et al. As expected, the biggest problems were encountered for the children with a severe type of ASD. The results of this study indicated that children with a severe type of ASD were more difficult to brush and also more difficult to treat, in case dental treatment is indicated. According to the parents, the most cited problem during the child’s last dental visit is the child’s behaviour in the dental office. This finding is in accordance with previous studies (Du et al. General dentists may not be adequately equipped to handle the behaviour of this specific child population. In a multi-center survey in the USA, it was found that only 10% of the American general dentists often perform dental treatment to children with special health care needs (Lai et al. Further research is also required to investigate the dissatisfaction with the dental care received of the 21% of the parents. It should be deepened out what aspect of the dentist or the dental treatment they are specifically dissatisfied with. Due to the scope and type of questions contained in the survey used in the current study, the causes for dissatisfaction could not be specified.From the results of this study, it appeared that children who had their last dental visit longer than 1 year ago, had a parent whose last dental visit was less than 1 year ago. It seems that having a child with ASD can be a barrier for frequent dental visits, even when the parent’s do visit the dentist themselves. Former research reported that children of mothers who did not visit a dentist regularly were at greater risk of not receiving dental care (Goettems et al. With regard to the limitations of the present study, parents rated the severity of the ASD and the cooperation of the child during dental visits themselves. Parental reports could be biased and caregiver’s assessment of behaviour may or may not represent the actual behaviour of the child. Furthermore, there was no mention on parental education and special needs education, which can affect parental perception. On the other hand, Marshall et al. In conclusion, the results of this study indicate that, despite that all children in this research have visited a dentist at least once, dental care of Dutch ASD children is not optimal. Due to the vulnerability of this patient group and their specific needs, it is of utmost importance to perform further research upon dentists’ knowledge and skills, treatment options and effective behavioural management techniques.


To expose causal mechanisms of the unusual phenomenon, continuous seismic waveforms are further conducted for examination. When the horizontal and vertical ground velocities of ground vibrations yield a difference in the phase angle close to 90°, coherence values between the air pressure changes and ground vibrations become large. This suggests that the pressure-shear vertical ground vibrations can drive air pressure changes. Meanwhile, the results shed light on investigating the existence of acoustic waves near the Earth’s surface using a partially confined space underground due to that the assumptions of the waves can propagate upward into the atmosphere driving changes in the ionosphere.Acoustic-gravity waves are generally considered to be one of the major factors that drive changes of the total electron content in the ionosphere. However, causal mechanisms of couplings between sources in the lithosphere and responses in the atmosphere and the ionosphere are not fully understood, yet. A barometer in the cave of the SBCB station records an unusual phenomenon of larger amplitudes in air pressure changes inside than those at the Xinwu station (outside). Accordingly, the comparison between the recorded data at the SBCB and Xinwu station can drive investigations of potential sources of the unusual phenomenon. Analytical results of phase angle differences reveal that the air pressure outside the cave at the Xinwu station often leads air pressure changes inside at the SBCB station at relatively low frequency bands. In contrast, the larger pressure changes at frequencies >  ~ 5 × 10 However, acoustic waves originate from ground vibrations that is obscured and difficult to be identified. The difficulty is mainly caused by seismic waves generally comprising of complex vibrations. Meanwhile, excited acoustic waves disperse in an open area  and become weak, accordingly.Previous studies13. Alternatively, the observation exhibits low-noise characteristics in caves and/or tunnels with rare artificial activities due to that the environment inside can mitigate influence from weather and artificial activities outside. The recorded data can be utilized as references for correcting responses of air pressure on distinct geophysical measurements14.A barometer is one of the scientific instruments that is generally installed above the Earth’s surface and is utilized to monitor variations of atmospheric pressure in a particular environment. The monitoring collects useful information  to help weather analysis and to forecast short-term changes in the weather for further evaluating impacts on human lifehttps://gps.moi.gov.tw/SSCenter/Introduce/IntroducePage.aspx?Page=Gravity4). Aisles inside the cave exhibit as a “U” sharp. The cave wall is rocks covered by calcium silicate boards and tiles. The width and the height of the cave is about 1.2–1.5 m and 1.8 m, respectively. The cave is under overburden soils with a thickness of about 40 m that causes the stable temperature and structural integrity14. Meanwhile, influence from groundwater is relatively small due to that the groundwater is static and its level is about 23 m lower than the cave. Doors were set up in the both entrances of the cave to avoid interference from artificial activities. A broadband seismometer was installed at the innermost of the cave , where is about 38 m away from the entrances, due to that the interior of the cave can eliminate the effects of the artificial activity and severe weather outside the cave. A barometer of the Setra’s Model 278 with an accuracy of ~ 0.3 mb and a sampling interval of 1 s was installed beside a broadband seismometer  for correcting unwanted influence from air pressure changes on seismic data16. All the efforts are benefit to high-quality data14. Note that the other barometer of the Setra’s Model 270 with an accuracy of about 0.05% of the full scale and a sampling interval of 1 min was installed at the Xinwu  weather station  with the altitude of ~ 141.5 m beneath the Eighteen-Peaks Mountain in the northeastern Taiwan  and outside (Xinwu) the cave from February 1 to 5 in 2016 are plotted in Fig. 17. The MSC was computed from the bivariate time series using a subroutine called “mscohere” in MATLAB. The MSC can identify significant frequency-domain correlations between two time series datasets. Meanwhile, phase angle estimates in the cross spectrum are useful for understanding where significant frequency-domain correlations exist. The differences in the phase angles of a particular frequency band were computed to understand the leading (or lagging) of air pressure changes at the Xinwu and SBCB station.We assessed the coherence of the amplitude within a particular frequency band using the Magnitude-Square Coherence (MSC) index–5 Hz  where p is the probability of success and is used in this study to show if the leading events were statistically significant. Notably, with an odds ratio near one, a success  was more likely than a failure. We calculated the odds ratios by dividing the number of the leading events by the number of the lagging ones within a moving window of 5 events. The odds ratios are obviously larger than one in particular frequency bands . In contrast, for the relatively-high frequency band (> 2 × 10–4 Hz), variations of the air pressure at the SBCB station can lead them at the Xinwu station. The large amplitude at the SBCB station is mainly limited within the relatively-high frequency band.To further examine the facticity of the unusual phenomena determined from relatively-unobvious values of the coherence, the odds rationed as p/-p where –4 Hz  waves. Thus, beside the air blowing in the atmosphere, large-scale ground motion forces the ground and perturbs the air that can be one of the candidates for resulting the lags. The large-scale ground motion amplifies variations in air pressure changes inside the cave due to the confinement of the surrounding rocks and influences surface air pressure. In other words, relatively-large variations should result from activities inside the cave or beneath the ground that shows the possible connection between changes in ground vibrations and air pressure changes.Variations of the air pressure at the SBCB station lead those at the Xinwu station in the relatively-high frequency band of > 2 × 1024. We further computed the coherence and the phase angle difference varying with frequencies between the vertical ground velocity and the air pressure at the SBCB station in the entire study period  were also analyzed in this study to understand how ground vibrations trigger air pressure variations. We down sampled the continuous seismic waveforms to a temporal interval of 1 min for fair comparison with the air pressure data Fig. a. We comWe constructed a background distribution by using the phase angle differences between the horizontal and vertical components of the seismic data at the SBCB station for the situation of the ground vibrations leading changes of the air pressure with coherence values > 0. Comparison distributions are constructed by the phase angle differences for the situation with coherence values larger than the thresholds varying from 0.1 to 0.4 with a step of 0.1. The background and comparison distributions are normalized by the total number of them. The normalized background distribution is subtracted from the normalized comparison one and the obtained residual is further divided by the normalized background distribution to understand the variations of the phase angle differences to the background. No obvious characteristics can be found from the variations for the coherence > 0.1 Fig. g. The vahttps://www.iris.edu/hq/)  retrieved from Incorporated Research Institution for Seismology  Fig. b and cha25. We assumed that the total number of moles and temperature of the air inside the cave are constant, while ground vibrations trigger changes in air pressure without break and/or damage. The volume of the cave in this study is approximately 270.00 (= 1.5 in width × 1.8 in height × 100 in length) m3. If the P-SV ground vibrations contribute variations of ± 0.25 mb in air pressure, the changes of the volume are about 0.14 m3, accordingly, for maintaining the product of the air pressure and the volume. If the changes of the volume are mainly contributed by the vertical component of the vibrations, the amplitude of the ground vibrations in the cave is about 10–3 m. The comparable results between the observation and the model suggest the large air pressure changes in a cave can be attributed to the P-SV-type ground vibrations.We try to evaluate air pressure changes dominated by variations of the volume of the cave through the ideal gas lawIf the P-SV ground vibrations can drive changes in air pressure, the question is how often the interaction can be detected. The interaction of events by using both the P-SV ground vibrations and a coherence value > 0.3 at each particular frequency can be determined. The total number of interaction events was generally maintained at 20 during the study period of 930 days . Thus, the air pressure retrieved from a barometer inside a cave is sensitive to the P-SV type vibrations.The novel observation sheds light on extension of the use of a cave and/or a tunnel. The amplified air pressure triggered by the P-SV type vibrations creates an excellent opportunity to study the origin of acoustic waves from ground motion. Air pressure data observed in a cave and/or a tunnel can become a treasure, while scientists want to prove the existence of acoustic waves that propagate upward and drive changes in the atmosphere. On the other hand, the P-SV type ground vibrations can be often observed in microseisms and surface waves after earthquake occurrence. When stable environments of air pressure are seriously concerned in a cave, the effects of the P-SV type ground vibrations have to be taken into consideration.Supplementary Information.


The Walker circulation is a thermally driven tropical atmospheric circulation in the longitudinal direction. At present, the ascending branch of the Walker circulation is over the warm pool in the tropical western Pacific and the descending branch is over the tropical eastern Pacific where sea-surface temperatures (SSTs) are cooler. How could the Walker circulation be a few tens of million years ago (Ma)? How did it evolve over tectonic time scales?et al. [2-concentration changes also play an important role in causing the strength change.Yan et al.  demonstr2 concentrations. Both are associated with the evolution of plate tectonics. Figure There are two major differences in climate conditions between the Early Cenozoic and the present: continental distributions and atmospheric COpool was far to the west relative to the present location, the cool pool was far to the east and the Walker circulation was much wider in the Early Cenozoic.By the Late Pliocene, the Indonesian and Panama seaways were all closed because of northward moving of the Australian and South American continents, resulting in a much narrower ocean basin in the Pacific. The warm and cool pools was pushed closer, causing the narrower Walker circulation at present.et al. [2 concentrations. This is consistent with previous simulations that a CO2 decrease would cause a sharper SST contrast between the western and eastern tropical Pacific and hence a stronger Walker circulation [Plate-tectonics evolution impacted on not only the width, but also the strength, of the Walker circulation. Yan et al.  showed tculation . They alet al. [et al. [2 decrease since the Early Cenozoic and how the coupling between the fluid and solid spheres led to the systematic global cooling. These questions remain great challenges to Earth sciences.The results by Yan et al.  have imp [et al.  are how Conflict of interest statement. None declared.


In this article we introduce a complete gradient estimate for symmetric quantum Markov semigroups on von Neumann algebras equipped with a normal faithful tracial state, which implies semi-convexity of the entropy with respect to the recently introduced noncommutative 2-Wasserstein distance. We show that this complete gradient estimate is stable under tensor products and free products and establish its validity for a number of examples. As an application we prove a complete modified logarithmic Sobolev inequality with optimal constant for Poisson-type semigroups on free group factors. In the last decades, the theory of optimal transport has made impressive inroads into other disciplines of mathematics, probably most notably with the Lott–Sturm–Villani theory , 42, 43 The starting point of our investigation are the results from , 11 and rization , 37 of trization , 41.One of the major challenges in the development of this program so far has been to verify semi-convexity in concrete examples, and only few noncommutative examples have been known to date, even less infinite-dimensional ones.To prove geodesic semi-convexity, the gradient estimateLet us briefly outline the content of the individual sections of this article. In Sect. estimate  and the q-Gaussian algebras satisfies ..Note addIn this section we briefly recall the definition and basic properties of the noncommutative transport distance aders to .x. One can show that quantum Markov semigroup (QMS) ifA QMS symmetric ifLet D(T) always means the domain of T. For all The generator of where Let carré du champ is defined asFor regular . By \documentKac type if the Haar state is tracial. In the following h . Similarly, given (Free permutation quantum group ment}SN+ ) Let \doAlthough many interesting functional inequalities like the Poincaré and the modified logarithmic Sobolev inequality only follow directly from ies see , 17)..\documenIn this section we prove that the complete gradient estimate refer to  and 2]  \documenrefer to  for freeLet Let For Letentclass1pt{minimaFor Let Then The same argument applies to free products with amalgamation if the common subalgebra over which one amalgates is contained in the fixed-point algebra of In this section we move beyond applications of the intertwining result Theorem Let For Moreover, Note that both the left and right multiplication by Therefore we have view of , we haveSince mentclass2pt{minimInspection of the proof shows that the same result holds if the generator of j-th coordinate and leaves the other coordinates fixed. Let Let G, a 1-cocycle is a triple H is a real Hilbert space, G, one can associate with a 1-cocycle To apply the theorem above to group von Neumann algebras, we will use the following Lindblad form for QMS generated by cnd length functions. Recall that for a countable discrete group G be a countable discrete group and G. Assume that the associated 1-cocycle H with an orthonormal basis Let By definition we haveL(G) so that Theorem G is finite, then the operatorThe elements n is even. The word length of The cyclic group Then the linear operators The symmetric group H. Define The matrices To extend the last example to the infinite symmetric group Let V is a form core for It is not hard to see that The argument for G is the ascending union of subgroups G such that for every n the QMS associated with If (Infinite symmetric group) Let G, a Følner sequence is a sequence G such thatG is called amenable if it admits a Følner sequence. We refer to [Recall that for a countable discrete group G be an amenable group, H such that Let To ease notation, we will only deal with G and j, let Let LetLet The group von Neumann algebra embeds into an ultraproduct of matrix algebras if and only if the underlying group is hyperlinear, so it might be possible to extend the previous proposition beyond amenable groups.G an amenable subgroup of G by d is the combinatorial graph distance. As in the case of free groups, one sees that (Amenable groups acting on trees) Let mentclass2pt{minimG on H is given by b is given byLet H and Put For example this is the case for More generally, the Cayley graph of a group is a tree if and only if it is of the form G is a group whose Cayley graph is a tree and the cnd function d is the combinatorial metric on the Cayley graph, then the QMS associated with If G is of the form As previously mentioned, mentclass2pt{minimG is a free group and If ained in , 40. Our


Geronticus eremita), the cross-sectional area of the test section measures 2.5 m × 1.5 m. The maximum achievable flow speed is approximately 16 ms−1. The wind tunnel exhibits a flexible outlet nozzle to provide up- and downdraft to allow for gliding and climbing flights. The current paper describes in detail the layout, design and construction of the wind tunnel including its control. Numerical simulations of the flow and measurements of the velocity distribution in the test section are presented. Apart from a non-homogeneous flow region in the mixing layer at the boundaries of the free jet, the test section exhibits a very even velocity distribution; the local speed deviates by less than two percent from the mean velocity. The turbulence intensity inside the test section was measured to be between 1 and 2%. As a constraint, a limited budget was available for the project. Four northern bald ibises were hand-raised and trained to fly in the wind tunnel.A blower-type wind tunnel for physiological bird flight experiments has been developed, constructed and evaluated. Since the birds to be investigated are rather big (Northern Bald Ibis, The online version contains supplementary material available at 10.1007/s10336-021-01945-2. Scientific experiments with flying birds can be performed when the birds are moving in their natural environment, namely in free air. The birds are equipped with instruments to collect or send the desired data, though the additional load negatively influences the bird’s flight performance due to the added mass and the changed aerodynamics  is reintroduced in Europe. Most research is conducted during the human-led migration flight, where human-raised juvenile birds follow microlight planes  and Seekirchen wind tunnel (Germany) have an area of 1.08 m × 1.20 m  and temperature (= 288 K) and is therefore referred to equivalent flow speed. The maximum speed of the manufactured wind tunnel was measured to be 15.7 msDuring the design process, several numerical calculations have been performed to evaluate the flow situation downstream of the outlet cross section using the computational fluid dynamics module of Siemens NX Siemens . To prev−1 and 1.2 ms−1 is achieved, respectively. As an estimate, a glide ratio (L/D ratio) of 9:1–10:1 emerges for this flow conditions, which appears reasonable for that species. Training flights showed that the birds could glide in this kind of flow. The observed flying position of the bird is in the center of the free stream or higher, which is roughly 150–180 cm above ground, hence more than the span of the species. For that, any ground effect—known from landing aircraft—will not influence the bird’s flight performance and therefore need not to be considered.Several horizontal slopes of the outlet nozzle have been designed in the numerical model to direct the flow. The streamlines of the nozzle in 0° position and with maximum inclination of 7° are presented in Fig. rectangular inlet segment taking up the fans (length = 84 cm);big concave converging nozzle (300 cm);small convex converging nozzle (300 cm);rectangular outlet section with flexible horizontal walls (120 cm).The wind tunnel is made up by four segments to facilitate manufacturing and transportation to the site of operation Fig. :rectanguThe honeycomb and the three wire screens are positioned downstream of the ventilators, between the first and the second segment. They are designed as frames carrying the particular component and can be clamped together to make up an additional package.The outlet segment exhibits flexible walls at the bottom and on the top. They can be adjusted in parallel to direct the stream upward (maximum + 7°) or downward (− 5°) to provide wind for gliding and climbing flights. Each segment exhibits the same construction technique; a strong wooden frame is covered with smooth panels which are glued onto the frame, making up the inner walls of the wind tunnel. Each part of a segment—sidewalls, top and bottom element—is detachable, so that only flat elements constitute the wind tunnel, except the walls of the nozzles, which are slightly curved.The wooden construction has many advantages. It is easy to tool with no expensive machines being necessary. Due to its rather low weight, it can easily be handled in the workshop and for transportation. Despite its great dimensions, the individual elements of each segment can be lifted and carried by two persons. Further, the costs of a wooden construction are much lower than those of a metal one, for example.As a drawback, the sensitivity of a wooden structure to humidity has to be mentioned. Since wood has the tendency to deform in humid conditions, water-resistant panels and bonded wooden rods are used. During one and a half years of operation under different ambient conditions, only marginal deformations can be observed, which do not affect the performances of the wind tunnel.All parts have been constructed at University of Applied Sciences Joanneum, and subsequently dissembled and transported for about 300 km to the site of operation, where the bird’s camp is located. There, the wind tunnel was reassembled.Due to the cost aspect, a cheap and reliable solution for the control was investigated as well. Each ventilator is equipped with a factory mounted frequency converter and control unit, and has a power supply of 400 V and a maximum current of 6 A. To start the ventilator a 24 V pilot contact has to be closed. Once the contact is enabled the speed of the ventilators can be controlled by an analog signal between 0 and 10 V, representing the rotational speed of the ventilators. This analog signal is adjusted using a potentiometer.−1 with an accuracy of 1% error of the full range and 1.5% error of the reading, respectively , and several channels for analog signals . Incoming signals are low pass filtered. Further, digital moving average filter is applied to smoothen the signals and get rid of any superimposed disturbances.All sensor signals and the motor signals are connected to a microcontroller. This central control unit is realized using an Arduino Mega, which is very reliable, easy to program and inexpensive Schmidt . The micThe microcontroller is programmed to generate eight pulse width modulated outputs to control each single ventilator. Those outputs are subsequently converted into voltage with four dual full bridge drivers. The speed is adjusted for all ventilators together, but the arrangement is such that the program allows to trim and offset the speed of each ventilator separately. Also, the pilot contacts of each ventilator are controlled individually to get information, if there is any malfunction. Since the reaction time of the fans is quite high, the filtering of the signals does not represent any problem for the control algorithm.With this setup it is possible to control the powerful ventilators with very cheap, but accurate devices. The 5 V based Arduino Mega is able to control the whole setup with a voltage of 400 V and 48 A current, resulting in a total power of 32 kW.A control box containing the microcontroller, the wiring and the sensor cables is located left of the outlet of the wind tunnel, so that it can be operated in the vicinity of the flying birds. It comprises an LCD display to indicate relevant data like the current equivalent air speed, temperature, and density.Furthermore, a large seven-segment display is installed on top of the wind tunnel’s outlet to inform the foster parent about the actual speed during the flight.All relevant data are stored on a micro-SD card with 1 Hz as ancillary data for the physiological experiments.−1 and 10.7 ms−1, the velocity distribution in three different planes was measured. The first plane is located directly at the outlet, whereas the second and third planes are located one and two meter downstream, respectively. This corresponds roughly to the flight position of the birds. Each plane exhibits 1450 measurement points, giving a good overview of the mean velocity distribution  of the aforementioned vendor. The velocity fluctuations U represent the turbulent fluctuations at the current position. CTA measurements of the flow velocity—hence turbulent fluctuations—have been performed the same planes as the mean-flow measurement given above. Measurements were taken at equidistant positions, with a spacing of 20 cm both horizontally and vertically, respectively, resulting in 13 times eight points for each plane. For the measurements the support of the sensor has been mounted on a stable tripod to avoid any movement or oscillations of the sensor, which would introduce erroneous velocity fluctuations. For the mean velocity 9.15 ms−1 was chosen.The turbulence intensity of the flow was assessed using hot-wire anemometry. The measuring principle is based on the changing electric resistance of a metal wire when exposed to different flow velocities. The wire of the sensor is extremely small to exhibit minimal thermal inertia and to establish potential flow conditions around the wire. A special electronic circuit regulates the voltage to keep the temperature of the wire constant. Those changes in voltage are a very accurate and dynamic measure for the actual flow velocity, once the hot-wire sensor has been calibrated. For the current application, a constant temperature anemometry (= CTA) equipment of Dantec Dynamics A/S was used , or a Göttingen-type (closed circuit) wind tunnel. However, the Northern Bald Ibises coped well with the turbulence level and exhibit a high willingness to fly. We assume that the aerodynamic performance of this large size birds is hardly affected by small scale turbulence, the inherent higher Reynolds number due to the bigger size and greater flight speed makes the large bird more resilient for separation, hence more resistant to sudden changes in drag. Further, it is assumed that a flying bird can be regarded a slender body, which is not prone for flow separation. Small birds are more sensitive in that respect  and left (0.2 m) of the free-stream to prevent the bird to incidentally fly out of the wind. We noticed that the birds sense the mixing region and quickly learned to avoid flying into the turbulent shear layer.The wind tunnel was constructed with the aim to conduct physiological and behavioral measurements. For a first experiment birds were fitted with respirometry masks with an air tube running from the mask to an oxygen analyser to measure oxygen consumption at varying flight speed. For this setup an experimenter was standing in the wind tunnel alongside the flying bird, holding and manually adjusting the tube.A blower type open circuit wind tunnel for bird flight experiments has been designed, built and evaluated. In the authors’ opinion, an open circuit wind tunnel is the most reasonable option for flight experiments with birds having a wingspan of more than a meter, both for technical and financial reasons. It turned out that rather simple methods were sufficient to design the wind tunnel based on its desired speed and outlet cross section. Evaluation showed that the desired maximum speed has been achieved, and that the velocity distribution at the outlet cross section deviates less than 2% of the averaged outflow velocity. The turbulence intensity within the test section was measured to be between 1 and 2%, which is a reasonable, but not a very low value.The used material, wood, is well suited for the construction and ensures reliable functionality, at least over a period of two seasons. Long-term experience is not yet available, but according to the condition of the device after the experiments, the authors assume continued functionality over several further seasons. The wind tunnel is intended to perform physiological and behavioral experiments; therefore, a perfect aerodynamic characteristic was not of primary importance.It was found that technically complex features, for example an acoustic optimization or visual projection of landscapes, are not necessary for the birds to fly in the artificial wind. It rather is important to accustom the birds as soon as possible to the noise and the flow of the wind tunnel. However, the bird training prior to flight experiments requires a considerable amount of time.The decision to design and construct a wind tunnel ourselves has proved true. The available budget was extremely small in comparison with the building costs of a closed-circuit wind tunnel, being approximately five to ten percent. The close interdisciplinary cooperation between engineers with expertise in fluid dynamics and biologists with experiences on behaviour and physiology of the species proved very fruitful. From a biological perspective, the wind tunnel fulfils the objective to provide a complementary methodological approach for research on physiology of bird flight under controllable and reproducible conditions.The authors hope that their experience with the low-budget wind tunnel will also inspire other working groups to create their own wind tunnel; the authors have no commercial interests and are willing to share their technical and biological experiences.Supplementary file1 (DOCX 27 KB)Below is the link to the electronic supplementary material.


Background: Male genital injuries are urological emergencies which if not promptly treated with correct therapeutic intervention may lead to loss of fertility due to infections and anatomical disruption of normalcy. This study highlights the clinical scenarios, etiology and outcome of male genital injury cases that were managed at a tertiary care center in Nepal. Such injuries are not frequently encountered as patients are hesitant to report such injuries. The present study is the first from Nepal which depicts a comprehensive report on male genital injuries.   Methods: A retrospective analysis of discharge summaries of the cases of male genital injuries was reviewed during June 2020. All the treated cases during the two-year period from April 2018 to April 2020 at Lumbini Medical College, Nepal were included in the study.  Results: There were eight cases of genital trauma admitted and treated during the study period. All the patients were males and age ranged from six to 71 years with a mean age of 33 ± 21.45 years. Fall injury and road traffic accidents (RTA) were observed to be the primary cause in the majority of cases.  Conclusion: Superficial injuries to the penis and scrotum do not require surgical exploration and could be managed conservatively. However, deeper and complicated injuries, testicular preservation, the functionality of the part and cosmetic issues are taken into consideration which might require a multi-disciplinary approach. Apart from the medical issues pertaining to genital injuries, there are legal and psychological aspects of such events too which should not be ignored. Protected within the groin they escape trauma; hence injuries are uncommon. However, when injured they are very painful and bleed profusely due to a rich vascular and nerve supply. Genital injuries are seldom life-threatening but may trigger psychological problemsThere are few case reports from Nepal on male genital injuries, however, detailed studies describing the patient profile, nature and cause of injuries have not been done. In this regard, the present research is a first from Nepal that attempts to study the cases of male genital trauma in detail to describe the profile of victims, circumstances of injury, modality of treatment and duration of hospital stay.A retrospective review of discharge summaries from the Department of Surgery of the Lumbini Medical College, Palpa, Nepal over the two-year period from April 2018 to March 2020 was conducted to identify patients treated for perineal injuries. The study included all the cases that had a history of injury to the male genitalia. The cases were identified by manual search based upon the diagnosis and history recorded. Discharge summaries with any of the keywords: penis, penile, scrotum, scrotal, perianal or perineum were selected. The case details were recorded for all the cases included in the study. Specific variables investigated in the study were age and gender of the patient, nature and manner of injury, mechanism of injury, anatomic site, treatment procedure, intra-operative findings and duration of hospital stay. The data thus obtained was then entered into a pre-structured proforma and exported to a Microsoft Excel 2018 spreadsheet and the results were expressed in frequencies, percentages, mean and standard deviation. The research was conducted in the Department of Forensic Medicine during June 2020 at Lumbini Medical College, Palpa, Nepal. The study was approved by the Institutional Review Committee of Lumbini Medical College, letter number IRC-LMC 08-D/020. Furthermore, permission to access and collect departmental data was obtained from the Professor and Head, Department of Surgery. A total of 15,125 cases were admitted during the study period in the Department of Surgery of whom only eight were cases of genital trauma who were admitted and treated. All the victims were male and age ranged from six to 71 years with a mean age of 33 ± 21.45 years. Fall injury and road traffic accidents (RTA) were observed to be the primary cause for perineal trauma in the majority of cases.. Management of male genital trauma is always a challenge because of cosmetic and functional requirements.Genital injuries in women are more common than men and mostly result from childbirth. Perineal tears in women related to childbirth are repaired by obstetricians. Forensic experts too encounter genital injuries in women during medicolegal evaluation of alleged sexual offences. In both circumstances the specific pattern of injury in women can help readily identify the nature of trauma. Genital injuries in women are usually easily repaired. On the other hand, there are diverse circumstances where the projected phallus in males could sustain traumatic injuries. As these traumas are rare, general surgeons may not be familiar with these urosurgical repair. The flaccidity of the pendulous portion of the phallus has a tremendous capacity to resist trauma as it restricts transfer of kinetic energy. On the other hand, the root which is fixed, is more prone to trauma in straddle injury or pelvic fractures. Due to the increased pressure within, the penis is more vulnerable to injury when erect. The loose and lax genital skin in the males can deform and slide away from the point of contact, however, if injured there is the potential of avulsion stripping entire penile and scrotal skin.The mechanism and severity of injury in male genitalia varies depending upon the location and the state of erectness or flaccidityThe manner of injury in most cases were accidents. Road traffic injuries and fall from height were the common reasons behind most cases of perineal injuries in the present study. Due to difficult geographical landscape and poorly maintained roads, road traffic accidents are common in Nepal. Sudden deceleration of a two wheeler on a pothole was the cause of blunt scrotal trauma in one of the three victims of road traffic accidents in the present study. The discharge summary of the other victim revealed blunt scrotal trauma leading to hematoma formation due to a sudden jerk while driving a farm tractor. One patient was hit by a motorbike and sustained injuries to the scrotum..In rural Nepal, the majority of people are engaged in agricultural activities. Degloving injury of the phallus with fracture was observed in one case, who had given a history of fall from a tree. Literature reveals grinding and crushing injuries to the scrotum while operating machinery, laceration following animal attack with or without complete amputation, burns, gunshot injuries to mention a few which were not reported in the present study. Aggressive sexual acts were the reason behind penile fracture in two cases in the present study.Masturbation in men is considered a compensation for unavailable sexAlthough not life threatening, genital injuries in males result in excruciating pain. Furthermore, the location of the injury in the genital area makes the person feel embarrassed and, in the meantime, reluctant to seek medical help. This might be one of the reasons for the under reporting of genital injuries..Male genital injuries range from simple swelling as a result of blunt trauma to more complicated injuries like avulsion and amputation. A multidisciplinary approach is required to manage a complicated male genital injury which involves a urosurgeon and a plastic surgeon. Psychological counselling is also an integral element in the treatment of such injuries. In cases where the restoration of the anatomical part is not possible in an amputated or a crushed phallus, the psychological trauma to the patient is enormous. Patients are likely to feel embarrassed and sexually incompetent. Chopping off the phallus as a punishment for sexual assault is not uncommon. An elderly man who had attempted sexual intercourse with a woman in Nepal was punished by his family with attempted bobbittectomy. Sexual abuse is rarely reported as the victim is ashamed and embarrassed. This provides the perpetrator the courage and impunity for further heinous crimes. Although the intense pain in the genitalia might not last long the psychological trauma is grave which the victim has to bear throughout the rest of his life. The dignity, self-respect and confidence of the person is shattered. The present study reported a case where a 71-year-old presented with scrotal laceration. The history was suggestive of domestic violence. In another case a 17-year-old sought medical attention after sustaining a penetrating injury of the scrotum with a snooker cue stick. Although the manner of injury sustained in this case is not mentioned, a possibility of sexual violence cannot be ignored. Patriarchal Nepalese society considers homosexual activity as a taboo; shame, guilt and fear of isolation constitute important reasons for not reporting such cases. The head and neck of victims are the prime target for perpetrators in cases of violence and homicide. However, genitals are commonly involved in order to intimidate someone, loss of masculinity as a consequence of physical assault is prosecuted under grievous injury and the perpetrator can be given a custodial sentence with 10 years of imprisonment and a fine of one lakh rupees.In accordance with Article 192, Section 2, Subsection ‘F’ of the criminal code of Nepal. Loss of sexual function due to traumatic injury to the spinal cord or associated nerves as a consequence of accident or intentional trauma is liable for compensation or a fine. Proper functioning of sexual organs is important not only for reproduction but for married life too. Male impotency is a ground for divorce in NepalThe retrospective nature of this study has its own inherent limitations. We could not find any previous studies from Nepal to compare the findings of the present study. Long term follow-up of the patients to study late complications in the form of urethral stricture, penile curvature, fertility and sexual functions could not be examined.Genital injuries, although a rarity in south Asian medical literature, are commonly encountered in south Asian countries including Nepal. Although most of the injuries sustained are accidental in nature, there are instances where the nature of injuries is intentional which could be elucidated by a detailed history. Anatomical repair of the trauma along with psychosocial and legal aspects of the event are not to be ignored. A multidisciplinary team approach is often required in the management of a case of male genital injury which should consist of a general surgeon, urosurgeon, plastic surgeon, psychiatrist and a medicolegal expert.All data underlying the results are available as part of the article and no additional source data are required.Consent for publication from patients or their families is not applicable to the present study because the present study is record-based where retrospective review of discharge summaries was done. The Institutional Review Committee of Lumbini Medical College, letter number IRC-LMC 08-D/020 which approved the present study agreed to waive the patient consent in this instance. The anonymity of the patient was maintained, and the data were anonymized, however, these alterations did not distort the scientific data. These findings have promise for urology emergency clinical care. There should be more information on female genital damage, especially in relation to sexual abuse. The socio-cultural context of genital injuries is well-described by the authors. The authors have also managed to touch on the forensic aspects of the matter by mentioning the appropriate sections of the Nepalese penal code. Longer-term repercussions of such injuries in terms of physical and psychological well-being may be included in the discussion section. While the authors' efforts are praiseworthy, additional research with a larger sample size is suggested.Is the work clearly and accurately presented and does it cite the current literature?YesIf applicable, is the statistical analysis and its interpretation appropriate?YesAre all the source data underlying the results available to ensure full reproducibility?YesIs the study design appropriate and is the work technically sound?YesAre the conclusions drawn adequately supported by the results?YesAre sufficient details of methods and analysis provided to allow replication by others?YesReviewer Expertise:Forensic PathologyI confirm that I have read this submission and believe that I have an appropriate level of expertise to confirm that it is of an acceptable scientific standard. Thank you for your time reviewing our manuscript and for your positive feedback. As the manuscript focused upon all the cases of male genital injuries treated at Lumbini Medical College, the study did not include genital injuries in females. As this was a prevalence study we did include all the cases during the two-year period (2018- 2020). Although genital injuries are not uncommon, most of the cases go to the specialty hospital with an uro-surgery facility, which is one of the reasons for the small sample size in the present study. We value your suggestion and would conduct future studies with a larger time frame and large sample. Minor changes: First paragraph second line: Delete "chances of".Fourth paragraph. Please rephrase the sentence as "Such injuries are not frequently encountered as patient are hesitant to report such injuries." Second paragraph first line: Delete "was carried out and " and replace with "of".Mention how the cases were managed briefly in the result section on the abstract and the manuscript.  Abstract: First paragraph: replace "genitals play" with "Human genitalia plays". Second paragraph: replace "victim" with "patient". Second paragraph: replace "are a rarity" with "have not been done".  Introduction: First paragraph, sixth sentence rephrase as "As these traumas are rare, general surgeons may not be familiar with these urosurgical repair."Third paragraph first sentence. Rephrase a "the manner of injury in most cares were accidents." Third paragraph. Please rephrase the third, fourth and fifth sentences as " Due to difficult geographical landscape and poorly maintained roads, road traffic accidents are common in Nepal. Sudden deceleration of a two wheeler on a pothole was the cause of blunt scrotal trauma  in one of the three victims of road traffic accidents in the present study."Fourth paragraph, second sentence. Change "falling" to "fall". Delete "while collecting cattle fodder."I would recommend deleting the fifth paragraph. The last sentence of the paragraph can be added to the fourth paragraph.24560873Seventh paragraph, last sentence rephrase as "In cases where the restoration of the anatomical part is not possible in an amputated or a crushed phallus, the psychological trauma to the patient is enormous. Patients are likely to feel embarrassed and sexually incompetent." Cite PMID  Discussion: Is the work clearly and accurately presented and does it cite the current literature?YesIf applicable, is the statistical analysis and its interpretation appropriate?YesAre all the source data underlying the results available to ensure full reproducibility?YesIs the study design appropriate and is the work technically sound?YesAre the conclusions drawn adequately supported by the results?YesAre sufficient details of methods and analysis provided to allow replication by others?YesReviewer Expertise:Meta-analysisI confirm that I have read this submission and believe that I have an appropriate level of expertise to confirm that it is of an acceptable scientific standard. Thank you for your time reviewing our manuscript and for your positive feedback. All the changes and edits that you have suggested are incorporated in the revised version.


Enuresis is defined as bedwetting in children aged five years and older when organic reasons have been ruled out. It can result in substantial psychological repercussions and uncomfortable circumstances for both the child and the family. Medical  and behavioral treatment are the basis for the treatment of enuresis. Alarm therapy is considered the first treatment modality of choice for enuresis with almost 50% cure rates are in the long term. Cooperation and compliance from parents and children are the cornerstones of the effectiveness of alarm therapy. Multiple factors, such as technical issues, might slow down the therapeutic response time. The objective of this study is to review the role of alarm therapy in the treatment of enuresis, its types, and its efficacy and to explore the factors that may increase or decrease its efficacy. The most frequent type of urine incontinence in children is nocturnal enuresis, often known as bedwetting. Enuresis is defined by the World Health Organization (WHO) International Classification of Diseases 10th Revision (ICD-10) as bedwetting in children aged five years and older when organic reasons have been ruled out .Despite the fact that enuresis is a discomfort issue that poses no harm to one's physical health, both the child and the family experience substantial psychological repercussions, causing stress and uncomfortable circumstances as a result of it. Also, it may have a detrimental impact on the development of self-confidence and the social skills of the child, as well as an association with poorer performance in school. It is classified as "primary" if no previous continence has been attained or "secondary" if at least six months of dry nights have been obtained -4.Among children at age five, about 15% have nocturnal enuresis and 15% of them resolve spontaneously annually . Enuresis is approximately two times more common in boys than girls, and it becomes less common with aging. According to a standard textbook, the prevalence is 7% for males and 3% for females at age five, 3% for males and 2% for females at age 10, and 1% for males and extremely rare in females at age 18 [Enuresis has multiple etiologies ranging from bladder hyperactivity, waking up difficulties when the bladder is full, and increased nocturnal urine output. The genetic cause also cannot be ignored .Because of the multiple and unclear factors leading to child enuresis, the treatment of enuresis is challenging for physicians and needs to be adjusted and individualized. The treatment of patients depends on the risk and benefit ratio and the therapeutic intervention effectiveness .Treatment in generalMedical  and behavioral treatment are the basis of enuresis treatment and should be started from age six in any child who has at least one enuresis episode per week. These modalities of treatment can be used alone or in combination. The gold standard treatment for enuresis is the behavioral night alarm ,5.AlarmThe alarm device consists of a sound system linked to a humidity detector that provides a warning sign once the urine has been detected by the detector . CompliaAlarm therapy is considered the first treatment modality of choice for enuresis; cure rates are almost 50% in the long term . In manyTraining the kid to wake up for micturition before incontinence or to prevent emptying the bladder while asleep is the goal of alarm therapy . HoweverAfter alarming, if there was a failure to awaken spontaneously by the children, their parents should wake them up to void the bladder on the toilet. If both (children and their parents) didn’t wake, which occurs frequently, making a code word agreed upon previously between the parents and the child can be advised to help in waking up .Ten to 12 weeks after the treatment, success rates are observed to be 50% and 80% while 12%-30% of cases can have a relapse in the first six months after treatment. However, a second course of alarm therapy can give a good response if a relapse occurs .Alarm typesIn many studies, four forms of night alarms were observed: sound, vibration, one that mixes an electrical impulse and a sound, and code words. The one that provides a sound is the most frequently used alarm. This type of alarm has been tested with various intensities and situations such as being associated with light or not, awakening the child immediately or after three minutes, putting a moisture sensor within the child’s underclothing or just on the bed, and finally alarming the parents or the kids only. However, there is no significant difference in terms of efficacy across the different forms of alarms .Optimal durationIf alarm therapy has been decided, the duration of the therapy should be two to three months or until being dry for 14 consecutive days. However, the most effective period of alarm intervention is anticipated to be 16-20 weeks of continuous therapy. Sleep deprivation can result due to repeated alarm, so one alarm per night is enough. Despite its high efficacy, choosing alarm treatment is critical because it is not easy to find the right families for this option and to inform them in a comprehensive manner, as the possibility of frustration and withdrawal among parents and children is not uncommon ,15.DiscussionThere are multiple factors that might slow down the therapeutic response time. One of these factors is the technical issues with the alarm such as the child's sweat or the battery not lasting long enough. Some devices only have a moisture detector, which might cause issues when trying to activate the alarm after an enuresis episode. Another aspect is the kind of fabric used for the moisture detector, requiring higher or lower absorption rates, as well as the alarm's technical quality, which can affect therapeutic efficacy .To conclude, alarms are still the preferred and most effective treatment for enuresis. Regarding alarm types, there is no consensus that there is a significant difference between the alarm types in terms of effectiveness. Cooperation and compliance from parents and children are the cornerstones of the efficacy of alarm therapy. Several factors may impede the therapeutic period of this treatment, which should be taken into account. Larger and further studies are needed to avoid these issues.


Maize seedlings are grown in Hostun sand with two different gradings and two different densities. The root-soil system is imaged daily for the first 8 days of plant growth with X-ray computed tomography. Segmentation, skeletonisation and digital image correlation techniques are used to analyse the evolution of the root system architecture, the displacement fields and the local strain fields due to plant growth in the soil. It is found that root thickness and root length density do not depend on the initial soil configuration. However, the depth of the root tip is strongly influenced by the initial soil density, and the number of laterals is impacted by grain size, which controls pore size, capillary rise and thus root access to water. Consequently, shorter root axes are observed in denser sand and fewer second order roots are observed in coarser sands. In all soil configurations tested, root growth induces shear strain in the soil around the root system, and locally, in the vicinity of the first order roots axis. Root-induced shear is accompanied by dilative volumetric strain close to the root body. Further away, the soil experiences dilation in denser sand and compaction in looser sand. These results suggest that the increase of porosity close to the roots can be caused by a mix of shear strain and steric exclusion. Depending on the considered activity  the radial extension of the rhizosphere can range from sub-μm to supra-cm scales1. Hinsinger et al.1 defined the rhizosphere as one of the most bio-diverse ecological systems on Earth. On the one hand, root secretions, together with bacteria, fungi, protozoa, and viruses, alter soil properties such as the capacity of soil to retain water2, or soil microstructure by binding particles together4. On the other hand, soil conditions  affect the growth rate and tropic responses of roots6. The overarching goal of this work is to contribute to the new field of bio-inspired geotechnics7 by understanding the best conditions to grow a healthy root system  while enhancing soil properties.Root-soil interaction is a strongly coupled phenomenon between a growing plant and soil. This interaction occurs in a portion of the environment with complex boundaries, which is referred to as the 8 suggested a compaction of the soil around the growing root, decreasing exponentially with the distance from the root. The model presented by Dexter is only in partial agreement with some more recent findings, such as the ones by Helliwell et al.9, Koebernick et al.10 and Lucas et al.11. These authors observed a small zone of increased soil porosity close to the root, generally attributed to a geometric effect due to the steric exclusion of soil particles near the root surface. Further from the root , no systematic trend was observed and both densification or porosity increase of the soil have been measured, depending on the soil nature and initial state. Hence, the interpretation of the local modifications of soil porosity in these conditions is still an open question.Here, the focus is on the local kinematics of an inert soil induced by the plant root growth, i.e., biotic aspects are discarded. An earlier study by DexterZea Mays L.) are grown in Hostun sand and 3D images of root-soil systems obtained by X-ray computed tomography are analysed to measure the porosity and the displacement fields in the soil located up to few cm from the root surface. The germinated seedlings are scanned in-vivo for 8 days. Two different gradings of Hostun sand and two different initial bulk densities are used in order to produce different initial soil configurations and investigate the relation of the latter with the soil response to the root growth. Local strain tensors are computed from the displacement fields and characterised with their first and second invariants .In this paper, maize plants  and during a rather short period (a few days). Maize produces a fibrous root system12 consisting in a group of roots with similar cross-section size and length. Roots do not penetrate deeply into the soil but rather create a thick network, which helps to hold soil particles together. According to the literature13, principal components of the maize root system develop within few days, with a growth rate of 1–4 cm/day and a mean root cross-section size  that facilitates phase segmentation in the image processing: the root system, soil particles, pores and pore water can be more clearly distinguished from each other. Hostun sand is considered here because its properties are well documented in the soil mechanics literaturead-hoc 3D printed base meshed with holes to allow watering from the bottom. The specimen is built in four main stages, as illustrated in Fig. the maize seed is germinated and then sowed in sand. Each seed is sterilised in a solution composed of 15% commercial bleach and 85% distilled water for 15 min, then rinsed in distilled water 3 times, and eventually soaked in water for 15 min. Seeds are transferred in culture dishes on a 1.5 mm thick germination filter paper, foil-wrapped, and placed vertically in the dark for 48–72 h at a fixed temperature of 19 ± 2 °C;18. Coarse and fine sands are deposited following the same procedure. Pluviation factors depend on the grain size  and on the desired bulk density . Fine sand (HN31) is packed with two different densities, a looser state with a relative density  after seed germination, sand deposition is conducted by dry pluviation to control the sand bulk density and to create a soil microstructure similar to that of natural sand depositsthe germinated seed is placed in the sand sample, during the sand pluviation, at a depth of about twice the seed height ;finally, specimens are watered from the bottom, with nutrient-enriched water. No additional water is added during the 8 days of the experimental campaign.Plant specimens are kept in a growth chamber under controlled temperature (19 ± 2 °C) and humidity (47 ± 4%). Each specimen is imaged using the X-ray computed tomography facility installed in Laboratoire 3SR  every 24 h ± 15 min for 8 days. Day 0 is defined as the day when the germinated seed is planted in the sand. Day 7 is the last day when the root system is imaged. Specimens are placed in the X-ray scanner for the time of the image acquisition only. After each scan they are returned to the growth chamber. 3D images have a voxel size of 40 μm, requiring a scan duration of about 2 h. Due to the unpredictable growth of the germinated seeds, three specimens per configuration are initially scanned. On Day 3, one specimen per configuration is chosen and analysed for the rest of the campaign. The specimen is chosen according to the orientation and length of the primary root. Supplementary Table Root-soil specimens are obtained by growing of a maize plant in a sand sample built in a cylindrical cell with an inner diameter of 5 cm and a height of 10 cm. Cell diameter was chosen as a trade-off between the field of view during the X-ray scanning and the spatial resolution. With the device adopted here, the voxel is equal to 40 μm. The cell is made of a polymethylmethacrylate (PMMA) tube sealed at the bottom with an To assess the possible effects of the X-rays on root growth, we conducted 3 reference experiments for each initial soil configuration outside of the CT scanner, with the same plant species as those imaged in the CT scan. In average, the leaf length, number of leaves and stem length were similar for the X-rayed and non-X-rayed plants grown in the same soil configuration. Furthermore, 10 days after the last X-ray scan, all the root systems were extracted and they exhibited primary roots of similar length and a similar number of first-order roots. Supplementary Table The aim of the image segmentation is to produce, from each 3D greyscale image of the root-soil system, a four-phased volume where each voxel of the volume is attributed uniquely to one of the four phases . Greyvalue thresholding is a basic way to segment images when phases consist of materials with clearly different densities, represented by different ranges of grey values in the image. This works here for the sand grains, which are clearly denser than the others components of the system, but cannot be applied for the segmentation of the roots, since their density is similar to the density of the pore water. A specific segmentation method has been developed for the root identification. Some image pre-processing steps are performed prior to the segmentation, and they are described in the following.19. For further details and a comprehensive description of the image pre-processing, the reader is referred to Anselmucci’s thesis20.For the set of images obtained for one given root-soil specimen, representative greyvalues attributed to each phase have to be comparable over all the images acquired in space (for every slice) and time (for every day), in order to ensure reliable quantitative phase assessments and effective measurements of the kinematics of the sand phase. Typically, the grey values of the peaks of the greylevel distributions are not expected to change over a set of images. Consequently, greylevel distributions are corrected by performing a linear contrast stretch of the images: the grey value of each voxel is scaled linearly with respect to the grey values at the peaks, such that they match for all the images . Since a grain diameter is about 38 pixels in the downscaled image, individual grains can be detected. This is achieved using a watershed algorithm22 is proposed. The main steps are summarised in Fig. For root body segmentation, a method based on the edge identification using the 3D variance filter implemented in Image-J23. At this stage, root body and big pores can still not be separated. To proceed, connected voxels of the same phase are clustered. Each cluster is labelled according to its volume. As shown in the frequency distribution of Fig. n times, where n is half of the radius The grey value of the root in the new image  and big pores is then used for thresholding, and the volume is binarised according to that threshold as per StamatiOnce sand particles and root system elements are identified, water and air phases can be segmented. The remaining voxels not assigned to root or sand are separated by a threshold value. Similarly to the sand segmentation, the threshold is chosen such that the volume of water identified from the image at Day 0 matches the water volume initially introduced in the sample.In the case of the fine sand, pore sizes and more particularly the size of zones filled with water when the sand is partially saturated  may be close to the voxel size. Therefore, most of the voxels attributed to soil pores can include both air and water phases and cannot be attributed rigorously to one of the two phases only. Consequently, water phase identification is only qualitative at the pore scale in the fine sand. In the coarse sand, pores are larger and water phase identification is more representative of the local water distribution. Figure Experimental research on cultivated maize plants and provision of maize seed comply with relevant institutional, national, and international guidelines and legislation.24 – Supplementary Figure Parameters of the root system architecture are extracted from the voxelised root phase identified above. The first step consists in the 3D skeletonization of the root system with the python module skimage.morphology.skeletonise_3D25. The root length density (RLD) is not correlated to the soil conditions either, with a RLD around 3000 m/m−3 at Day 7 in all the configurations , the root system reached the bottom of the cell (at a depth of 100 mm below the sand surface) before Day 3, whereas the roots stopped at a depth of around 44 mm at Day 3 and were not able to grow deeper even after 7 days in the denser HN31  in the looser state, root penetration is slower than in the looser fine sand, and the root reaches a depth of 87 mm at Day 7.The higher resistance to penetration in denser sand can be interpreted as an effect of the sand macroscopic friction angle, which is higher at higher density. According to three drained triaxial compression tests performed under a very low confining pressure of 5 kPa  on Hostun sand of various densities, the friction angle is 46.8° for the denser state and 37.7° for the looser one28. In coarser sand, the pores are larger, the capillary rise is thus lower, pore water is concentrated at the very bottom of the sand sample and roots do not reach such depth, even after 8 days. In the denser fine sand, pore water is initially homogeneously distributed. Nevertheless, roots fail to penetrate the soil and take up water present at the top of the specimen, which gets depleted in water, leaving no possibility for the roots to reach pore water. In looser fine soil, pore water is initially homogeneously distributed in the sand sample and the root system deploys in the whole wet sand volume.The root system growing in the looser fine sand is the one developing the greater number of laterals  with more than 83 lateral roots at Day 7, whereas the number of lateral roots for the systems in the denser fine sand is 24 and that in the looser coarse sand is 14 , and resulting root systems are conform to what is commonly expected in these conditionsIn the following, root development is considered as a loading applied to the soil, and the remainder of this paper is devoted to the study of the mechanical response of the soil to such a loading. Sand porosity is directly computed as the ratio of air and water filled pores volume to total soil volume from so-called trinarised 3D images.The initial states of the samples are displayed in Fig. 20. The distance from the root surface (and from the root tip) ranges from 0 to more than 16 mm. The 16 mm distance was chosen because it was noted that porosity did not change beyond that distance. Porosity profiles can be drawn at different times . However, they were not further calculated three days after the shooting day of the considered root because other elements affecting the sand porosity  interfered with the root body. It is worth noting that the range of variation of the porosity with the distance from the root is well above the fluctuations observed in the initial state and is thus representative of the alteration induced by the root growth.The local porosity distribution around the primary roots presented in Fig. i and that at day 0) for three root tips , and for every soil condition. The mean porosity profiles and the standard deviation from the mean are also presented in the last column of Fig. In the same way, Fig. 11. In previous studies10, porosity increase was attributed to steric exclusion, which depends on sand packing and the interface between the root and the grains. Steric exclusion could also explain observations made here in the looser sands, since it concerns few particles layers from the root surface31. For the coarse looser sand, this steric exclusion, involving almost a single layer of particles, is very limited. This is probably because roots are more prone to use the existing large pores to penetrate soil, thus limiting the movement of particles. In the denser sand, the porosity increase involves too many particle layers to be the consequence of steric exclusion only.A significant increase of porosity in the direct root vicinity is noted regardless of the initial soil state. Nevertheless, the distance range over which such a porosity increase occurs depends on the initial soil state. The profiles of mean porosity indicate that the distance range is relatively large in the case of the fine denser sand, reaching a distance of about 10 mm , whereas in looser fine sand, dilation is observed near the root surface while compaction is noted further away. Consequently, the volumetric deformation of the soil in response to root elongation depends on the initial soil density. The case of the coarse sand in the looser state can be considered as an intermediate case between the two soil responses described above for fine sand: further from the root, porosity stabilizes close to the the initial bulk porosity with a slight tendency to compaction only.9).Finally, the global spatial range over which sand porosity is affected (up to a distance of 10–15 mm) by the root growth is wider than what is usually reported in the literature, typically 1 mm in the rhizosphere from the root surface. This difference can be explained by the fact that the grain size used in this study is larger than the one usually considered in previous studies 33 between a reference configuration – Day 0 – and a deformed one – the rest of the chronosequence. A discrete DIC approach is adopted for the coarse Hostun sand: each individual sand particle is detected, the position of its centre of mass is calculated and tracked in space and time to measure particle displacements. A local DIC approach is used for small fixed-size cubic sub-volumes of fine Hostun sand, called correlation windows. Here, the total specimen volume containing fine sand is divided into a structured grid of about 158401 correlation windows, with a side length of 1.3 mm. Displacements and strains are computed using the open source software SPAM – Software for Practical Analysis of Materials34 – at each measurement point (centre of mass for coarse sand and centre of correlation window for fine sand). Concerning the fine sand, local strains are calculated from the displacements obtained from image correlation in the finite strain framework, using a 3D implementation of the method proposed by Geers et al.35. The first invariant – the volumetric strain F − I). The second invariant, which represents the maximum shear deformation – the deviatoric strain 36, and discrete strain is computed according to Bagi’s formulation37.Growing plant roots not only invade existing pores, but they also create their own space by displacing soil particles . To do this, the coordinates of the correlation windows that contain portions of the primary root are identified, and the strains of the portion of soil surrounding the specific root are extracted. Figure 16 – at different initial relative densities27 are compared to the strain variations observed around the primary root  on Hostun sand HN31 – previously called Hostun RFThe presented work provides new data concerning the mechanical response of sand to the natural growth of plant roots. The specific protocol designed to reproduce the early stages of maize root growth at laboratory scale reveals that the cross-section thickness of the roots and the root length density do not depend on the initial soil configuration. The data obtained from X-ray computed tomography are processed to extract measurements on both soil kinematics and root system architecture. The analysis on the root system architecture indicates that the initial density of the soil is the parameter that affects the most the final architecture. This is mostly confirmed by the depth reached by the root tips and the number of second-order laterals. In coarser sand, the lower capillary rise hinders access to water, which limits especially the development of lateral roots. The growth of the maize roots increases the sand porosity in the vicinity of the root and the dilated zone characteristic length depends on the initial density of the soil, about The novelty of this work lies in the quantification of the soil strain tensor by image analysis during plant root growth (in vivo). It was found that while elongating, roots shear the sand, which translates in a dilation of the sand in the vicinity of the root body. Initial density affects the response of the sand further away from the root, where denser sand experience low-magnitude dilation, whereas looser sand experience compaction. This behaviour is also observed in sand subjected to compression under a few kPa of confining pressure. Hence, two sharply divergent patterns have emerged from the strain analysis far from the root. However, a common dilatant response is found immediately around the root. Therefore, on the basis of these results, we may assume that the porosity fall-off trends described in this paper and in prior studies are likely to be correlated to the shear induced by the root elongation, and not only from steric exclusion.41. These open issues are left for future work.The results of this study have important implications on how to optimise plant growth and yield in agriculture. Literally, an overly stressed soil will not be conducive to productive crops. Additionally, the root-induced deformation mechanisms highlighted in this study have the potential to inspire the design of new geotechnical probes meant to penetrate the soil and to assess soil local fabric and stress from local deformation fields. One of the major challenges in validating the root architecture deployment behaviours is the difficulty to control or assess the water content distribution during in-vivo experiments. Additionally, a smaller incremental step of observation will give more specific information on phenomena still under investigation, such as the link between root branching chronosequence and soil features. Such results could be obtained by fast-neutron tomographySupplementary Information.


During the second half of the twentieth century the figure of merit has gradually improved. This has come about through the selection of semiconducting materials with improved electronic properties and a small lattice thermal conductivity. Further advancements have been achieved by enhancing the scattering of phonons. There is also the possibility of improving the so-called power factor, that is the part of the figure of merit that contains the Seebeck coefficient and the electrical conductivity. However, it appears that it will be increasingly difficult to make further advances because of the manner in which these quantities vary with the Fermi energy. It is shown that this may set a practical limit on zT. Nevertheless, it may be possible to reach an efficiency or COP of about 40% of that of an ideal thermodynamic machine.The efficiency of a thermoelectric generator and the coefficient of performance (COP) of a thermoelectric heat pump are related to the hot and cold junction temperatures and a quantity known as the figure of merit,   One might expect, then, that the power factor should be four times larger for silicon than for bismuth telluride. However, this turns out not to be the case. The electron mobility falls rapidly as impurities are added to silicon in order to optimize the carrier concentration. Ionized-impurity scattering is less noticeable in bismuth telluride because its much larger dielectric constant shields the electrons. It is just possible that a high electron mobility might be maintained in heavily-doped silicon if the necessary impurities are present as charged nanoparticles rather than as ions [The value of μ 3/2 equal to its value for pure silicon combined with a glass-like lattice thermal conductivity. Such a material with an optimized carrier concentration should have ZT equal to about 4 and a Seebeck coefficient approaching ±400 μV/K. This would seem to be the best that one might hope for in the near future.ZT. The problem is that the Seebeck coefficient varies more or less linearly with the Fermi energy whereas the carrier concentration has a near exponential dependence. As β increases, the optimum Seebeck coefficient becomes somewhat larger but the carrier concentration becomes much smaller. zT is expected to vary with β. Once zT becomes greater than unity, further improvement requires much larger values of β. β is equal to about 0.4 for a bismuth telluride alloy with zT = 1 and has to rise to about 3.2 for zT to reach 4. A further doubling of β only allows zT to climb to about 5.In fact, even if larger values of β are forthcoming, it may still be difficult to obtain much greater values of zT close to unity near room temperature. This allows us to make single-stage thermoelectric refrigerators that cool to about 90° below room temperature. A thermoelectric heat pump operating with a temperature difference between the source and sink of 30 degrees has a coefficient of performance of about 1. With zT = 4 the coefficient of performance would rise to about 3 for the same hot and cold junction temperatures. This would make thermoelectric heat pumps very attractive but even now they can be a viable alternative to conventional devices. One of the most convincing demonstrations of the virtues of thermoelectric air conditioning was a long-running trial on the French railways [At the present time there are a few materials with railways . A 20 kWZT were equal to 4 the efficiency would be nearly 40% of that of an ideal machine. It is remarkable that this could be achieved with a system having no moving parts and capable of operating over a wide temperature range.Perhaps the most important potential application is electrical generation from a low grade heat source. If 6.ZT. Nevertheless, with this quantity rising to about 4, thermoelectric energy converters should still find widespread application.In summary, following the significant improvements in materials during the second half of the twentieth century it should now be possible to make thermoelectric generators and heat pumps that can compete with conventional devices. However, because of the manner in which the Seebeck coefficient and the electrical conductivity depend on the charge carrier concentration, it will be increasingly difficult to attain further improvements in the figure of merit