The number of patients with oral hypofunction is increasing with the aging of the population, and such hypofunction increases their risk for dysphagia and malnutrition. The purpose of this study was to measure the hardness of commercially available confectioneries, select a confectionery with a hardness suitable for masticatory training for elderly patients, and evaluate the effects of 1-week masticatory training on oral function .The average hardness values of 25 confectioneries were determined. Among them, one of the softest confectioneries that the patients felt as “chewable but difficult to chew” was selected as the training confectionery for each patient. The patients in the training group continued training, which involved eating of approximately 5 g of one selected confectionery daily for 7 days. The patients in the control group did not undergo any training. Oral function  on the first day and after 7 days was evaluated and compared between the groups.The occlusal force of the patients in the training group increased significantly. However, their masticatory ability and tongue pressure did not change significantly.Patients aged 65 years and older underwent masticatory training, which involved eating of a confectionery with its hardness adjusted individually for a week. A significant increase in the occlusal force was observed, suggesting that masticatory training using confectioneries with a hardness suitable for each patient is effective. The study process and procedures were explained to all participants, and written informed consent was obtained. This study was registered in the UMIN Clinical Trials Registry .,The participants were outpatients and home-visit patients who visited the dental clinic of our hospital from July 2021 to March 2022. Patients aged 65 years or older with a Dysphagia Severity Scale (DSS) score of 3 (water aspiration) or higher were included in the study.Twenty-five commercially available confectioneries (rice crackers and biscuits) were provided. The hardness of these confectioneries was measured using a creep meter  based on the universal design food (UDF) product test method.The method of measuring the physical properties (hardness and adhesiveness) of the UDFs was determined in accordance with the standard regulations of foods for individuals with difficulty in swallowing indicated by the JCC.162) using the maximum force required for the first compression. The measurement conditions were as follows: load cell of 20 kg, compression rate of 10 mm/s, and plunger diameter of 3 mm. Because the test food could not be transferred to the measurement container, the clearance was set to 30% of the sample thickness, and the measurement temperature was set to 20 ± 2 °C. The measurements were performed five times per sample, and the average values of the three values, excluding the minimum and maximum values, were calculated.In this study, we measured the hardness  was performed on the first day and the second measurement after 7 days. Based on the results of the preliminary survey, the training duration was limited for a week because many participants claimed fatigue and refused to eat a confectionery with a hardness that was adjusted individually for more than a week.Age, sex, and complications were investigated via a medical record review. At the beginning of the study, the Eichner classification, number of occlusal support areas with prosthetics, and DSS score were assessed.The participants were instructed to bite on the pressure-sensitive sheet of Dental Prescale II®  in centric occlusion for approximately 3 s, and the occlusal force was measured. The value measured in the first measurement was used; the value in the second measurement was used only when the first measurement failed. Less than 500 N of occlusal force was defined as a decreased occlusal force.The masticatory ability was evaluated using 2 g of glucose-containing gummy jelly . The value measured in the first measurement was used; the value in the second measurement was used only when the first measurement failed. A glucose concentration of <100 mg/dL was considered to indicate masticatory hypofunction.The tongue pressure was measured using a tongue pressure-measuring device . Three measurements were performed, and the average value was used as the measured value. Less than 30 kPa of tongue pressure was defined as a low tongue pressure.P < 0.05.The measured values were expressed as medians (quartiles). The Mann–Whitney U test was used to compare patient age and sex. Fisher's exact test was used to compare the Eichner classification, number of occlusal support areas, and DSS score. The Smirnov–Grubbs test was used to test for outliers. The Wilcoxon signed-rank test was used to assess the differences in the occlusal force, masticatory ability, and tongue pressure before and after training. The significance level was set at The method for determining the required number of cases was calculated on the basis of a previous report.Forty-four patients were enrolled in the study, of whom total of four withdrawn . Thus, 42), first quartile value , median value , third quartile value , and maximum value  were selected. In the Smirnov–Grubbs test, the maximum hardness of the confectionery (Wazanokodawari®) was considered an outlier (P = 0.0027). The second most difficult to chew confectionery   was also added, and six types of confectioneries were prepared. The patients in the training group were fed six types of confectioneries in a soft order before the start of training. Among the choices of “chewable without difficulty,” “chewable but difficult to chew,” and “not chewable,” one of the softest confectioneries that the patients felt as “chewable but difficult to chew” was selected as the training confectionery.The average hardness value of the 25 types of confectioneries was calculated, and a graph arranged in the order of softness was suggested . The minP = 0.046). However, there were no significant differences in the masticatory ability (P = 0.896) and tongue pressure (P = 0.274). Additionally, the control group showed no significant difference in all evaluation items  between the two measurement points.In this study, the hardness of commercially available confectioneries was measured; masticatory training was conducted for 1 week using a confectionery in which the load was adjusted for each patient; and the effect of training on oral function was examined. As a result, the occlusal force of the patients in the training group increased significantly.,There are several reports on the effect of masticatory training using foods on oral function. Gummies and gums are found to be highly useful for analyzing the stability of masticatory movement pathways and rhythms; however, because their hardness and amount are constant, their use is inappropriate for analyzing masticatory function in the course from the start of mastication to swallowing and is also difficult for patients using dentures because of adhesiveness.,,Previous studies had not set an appropriate load amount of training foods for each participant but used training foods with certain properties for all participants.,Several studies have shown that masticatory training improves the masticatory ability in the elderly population. One study in which masticatory training food (pure) was eaten three times, the level of mastication and swallowing increased.The tongue pressure did not increase significantly in this study. This is because the load on the tongue might have been insufficient because rice crackers and biscuits are water-absorbent and tend to become boluses at an early stage when mixed with saliva. Further, the masticatory ability did not increase with masticatory training. In masticatory training, the increase in the maximum occlusal pressure and masticatory efficiency may not always be parallel. Another report stated that masticatory ability and body function were significantly improved 4 weeks after the start of masticatory training.In this study, there were no differences in age, sex, Eichner classification, number of occlusal support areas with prosthetics mounted, and DSS score between the two groups. There were no factors besides masticatory training that affected the study results regarding patient masticatory and swallowing functions.One limitation of this study is that the target of the load was 50–70% of the maximum muscle strength, while the actual setting of the load was determined by the subjective sensation of the patients. In the future, when an appropriate method for measuring the training load is established, it will be necessary to measure it accurately. Another limitation is that we focused only on the hardness of the confectioneries; however, the other physical properties of foods (adhesiveness and cohesiveness) differ among confectioneries, which can also affect masticatory function.In conclusion, patients aged 65 years and older underwent masticatory training in which they ate a confectionery with a hardness adjusted individually for a week. A significant increase in the occlusal force was observed, suggesting that masticatory training using confectioneries with a hardness suitable for the individual is effective. In the future, it could be significant to also investigate whether the improved oral function is maintained after masticatory training is terminated.The authors declare no conflicts of interest with respective to the research and publication of this article.


All the changes the skin goes through, peaking at flaccidity, occur in the dermis and hypodermis, leading to loss of support and a lower capacity to totally accommodate displacements or any loss of subjacent volume, bringing about the onset of furrows and sagging. Improvements in facial sagging may be obtained with the administrations of substances like poly‐L‐lactic acid (PLLA), which triggers a tissue response through a controlled inflammatory reaction.Compare the tissue distribution of the particles of PLLA of both products available in Brazil (Sculptra® and Rennova Elleva®) during and immediately after their subdermal administrations, with 22G cannulas, through high‐resolution ultrasound imaging.A total of four patients aged between 18 and 64 years had the inner part of the upper arms divided into eight quadrants and treated with 16 ml of each product, reconstituted to correspond to 9.5 mg/ml. The sites where PLLA was injected were analyzed through the high‐resolution ultrasound during (dynamic imaging) and immediately after the procedures (static imaging).During Sculptra® injection, high‐resolution ultrasound revealed that its distribution did not follow the trajectory of the cannula homogeneously. It was characterized by a more hyperechogenic central portion and an anechogenic peripheral portion, forming discrete posterior acoustic shadowing at times. Regarding Rennova ELLEVA® injection, the high‐resolution ultrasound analysis showed a homogeneous distribution of the product across the subcutaneous tissue following the trajectory of the cannula without formation of significant interface with the surrounding tissue, maintaining the sonographic aspect of thinly granulated hyperechogenic deposits, with strong posterior acoustic shadowing during and immediately after its administration.Static and dynamic high‐resolution ultrasound imaging show a more homogenous distribution of PLLA particles with the use of Rennova ELLEVA® when compared with Sculptra®, which may induce the formation of capsules and a subsequent more dispersed fibroplasia, with larger area of action and a possible better therapeutic result. The interest of this article lies in its originality, highlighting the differences in the tissue distribution of two different brands of PLLA particles, which can impact the clinical response to the two products ‐ which we are researching and seems to interfere with the increase in dermal thickness. Compare the tissue distribution of the particles of PLLA of both products available in Brazil (Sculptra® and Rennova Elleva®) during and immediately after their subdermal administrations, with 22G cannulas, through high‒resolution ultrasound imaging. Static and dynamic high‒resolution ultrasound imaging show a more homogenous distribution of PLLA particles with the use of Rennova ELLEVA® when compared with Sculptra®, which may induce the formation of capsules and a subsequent more dispersed fibroplasia, with larger area of action and a possible better therapeutic result. In the dermis, type I collagen fibres undergo structural changes that reduce their tension force, with higher levels of degradation and fragmentation and lower rates of fibroblast replacement, thus leading to a proportional increase in the amount of type III collagen over time. The elastic fibres gradually become frayed, without the terminal fibres that extend to the epidermis.Improvements in facial sagging may be obtained with the administrations of substances like poly‐L‐lactic acid (PLLA), which triggers a tissue response through a controlled inflammatory reaction. The slow degradation of the material peaks with the deposition of collagen around it. Such response is subject to the characteristics of the injected product, the technique used regarding the administration of the injections in the tissue and the characteristics of each patient.Biocompatible and biodegradable, the PLLA is an injectable synthetic polymer of the alpha‐hydroxy acids family of amphiphilic nature, which forms colloidal micelles in water.The difference in terms of visual presentation of both products is in the lyophilization process: when it comes to Sculptra®, it happens in the vial, which makes PLLA be compressed; regarding Rennova ELLEVA®, it happens out of the vial during the preparation of the product, resulting in its presentation in powder form and making its reconstitution easier.The aim of this study was to compare the tissue distribution of the particles of PLLA of both products during their subdermal administrations, with 22G cannulas, through a high‐resolution ultrasound imaging exam performed during the procedures.High resolution ultrasound is a dynamic and non‐invasive imaging method that allows for the evaluation of fillers and biostimulators since such substances have their own characteristics and densities.33.1Both vials were prepared 24 h prior to the procedures. Distilled water was used for the reconstitution, in the amount of 10 ml for Sculptra® and 14 ml for Rennova ELLEVA®, and stored under refrigeration. At administration, the products were diluted, totalling 16 ml for Sculptra® and 22.4 ml for Rennova ELLEVA®, which corresponds to a concentration of 9.37 mg of PLLA in both vials.3.2A total of four patients aged between 18 and 64 years (mean age of 45 years) signed the free and informed consent term, which detailed the procedure itself and its objectives. Photographs were taken before and immediately after the injections. The inner part of the upper arms was divided into eight quadrants as shown in Figure 3.3In each quadrant, 2 ml of the product was injected using the fanning technique (0.4 ml per retroinjection), totaling 16 ml of the product in each upper arm. Sculptra® was used in the right upper arm, whereas Rennova ELLEVA® was used in the left upper arm. Administrations were performed using the same applicator and the same technique, with Rennova cannulas 22G × 7 cm for both sides. No cannula clogging could be observed throughout the procedures.3.4High resolution ultrasound scan with a high frequency transducer (18 MHz) was performed with a Logiq e® scanner . The sites where PLLA was injected Figure  were ana4While Sculptra® was being injected, the ultrasound revealed that its distribution did not follow the trajectory of the cannula homogeneously. It was characterized by a more hyperechogenic central portion and an anechogenic peripheral portion Figure , formingFigure Regarding the administration of Rennova ELLEVA®, the ultrasound analysis showed that during its administration there was a homogeneous distribution of the product across the subcutaneous tissue following the trajectory of the cannula without formation of significant interface with the surrounding tissue Figure . The sonFigure 5Since 1999, injectable PLLA has been used as a cosmetic filler for the correction of skin volume loss caused by ageing. Gradually, progressively and lastingly, it promotes natural and harmonious results with low risks of adverse effects.It is a polymer with high molecular weight (140 kD) of the alpha‐hydroxy acids family, derived from the lactic acid, with properties of self‐organization and the formation of colloidal micelles in aqueous solution. These micelles act as substrate, which will promote cell activity that leads to or facilitates molecular and/or mechanical signalling so that tissue regeneration can be optimized without any local or systemic harmful response to the host.dispersed as lyophilized powder in a sterile vial, added to carmellose sodium or to carboxymethylcellulose sodium and non‐pyrogenic mannitol. Before administration, it must be diluted in distilled water for injection, and it will be absorbed in 24–48 h.It consists of smooth‐surfaced spherical particles, with a diameter that ranges from 40 to 63 μm. The particles are Two hours after the implantation of PLLA in the deep reticular dermis or the superficial hypodermis, a mild inflammatory reaction occurs in response to the foreign body, during which macrophages undergo fusion to form giant cells which try to phagocytize the particles. Edema appears to facilitate cell migration. Between seven and 10 days after the implant introduction, the macrophages secrete chemotactic and growth factors to trigger the attraction of fibroblasts and the proliferative phase of reconstruction. Fibroblasts secrete components of the extracellular matrix, initially type I collagen followed by a smaller production of type III collagen.Fibroblasts will then isolate the implant with a fibrous collagen capsule, where each particle will be encapsulated independently from the others with substantial deposition of type III collagen close to the particles and type I collagen at the periphery of the encapsulated PLLA, thus forming mature vascularized fibrous tissue. Therefore, neocollagenesis and the consequent increase of dermal tissue, which establishes the desired cosmetic result, are obtained by marked fibroblastic activity and proliferation around each particle. It will be followed by the PLLA degradation in monomers of lactic acid through hydrolysis without any indication of acute inflammatory response.The mechanism of action of PLLA has important practical implications, including administration procedure, optimization of results and minimization of adverse effects.The lyophilization process, which is performed in the vial of Sculptra® and out of the vial of Rennova ELLEVA® during the preparation of the product, establishes important differences concerning the distribution of PLLA particles in the vial and during the reconstitution. Therefore, in order to have a more trustworthy observation of the distribution of the particles in the tissue treated with the different presentations of the product, the total volume and the amount of the product per ml were exactly the same when dilutions were carried out. It is important to point out that the amount of emulsifying agents in both fillers is practically at the same proportion, so the same amount was kept in the injected volumes.Right after the administration of PLLA, the injected volume promotes changes that can clearly be noted. Such changes may remain for 2 or 3 days until the total absorption of the diluent,There is a very small number of studies in the literature that discusses the sonographic aspect of PLLA, a solid substance to be diluted in water for injection. It is rapidly reabsorbed in up to 2 weeks after administration, leading to an increase in thickness and echogenicity of the subcutaneous tissue. Focal deposits are hardly ever observed in the application sites.Despite the better distribution of Elleva® in the subcutaneous tissue through the cannula trajectory, the posterior acoustic shadow may hinder the analysis of the posterior subcutaneous tissue in response to the product. Further studies to evaluate the sonographic aspects of the different PLLA presentations throughout time should be carried out.6In the current study, high‐resolution ultrasound imaging could statically and dynamically show a more homogenous distribution of PLLA particles with the use of Rennova ELLEVA® when compared with Sculptra®. This better distribution that occurs with the former product may induce the formation of capsules and a subsequent more dispersed fibroplasia, which will promote a more effective neocollagenesis response due to the larger area of action and a possible better therapeutic result. Further comparative studies should be conducted to confirm the results found here.Marisa Gonzaga da Cunha: Conceptualization ; Data curation ; Formal analysis ; Funding acquisition ; Investigation ; Methodology ; Project administration ; Supervision ; Validation ; Visualization ; Writing – original draft . Rosa Sigrist: Data curation ; Formal analysis ; Investigation ; Methodology ; Project administration ; Software ; Supervision ; Visualization ; Writing – original draft .The author declares that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research reported.Patients signed the free and informed consent form approved by ethics committee in research, registration number 1964958.


This work investigates the impact of cracks and fractural defects in solar cells and their cause for output power losses and the development of hotspots. First, an electroluminescence (EL) imaging setup was utilized to test ten solar cells samples with differing crack sizes, varying from 1 to 58%. Our results confirm that minor cracks have no considerable effect upon solar cell output, and they develop no hotspots. However, larger cracks can lead to drastic decreases in the output power, close to − 60%. Furthermore, as the crack area increased, there was a further increase in the cell's temperature under standard test conditions. On the contrary, no hotspots were found for the solar cells affected by significant creak areas (crack percentage > 46%) because there were insufficient areas to develop a hotspot. Last, a comparative analysis with solar cells affected by potential induced degradation (PID) was made. We found a strong relationship in the output power losses, and the PID test critically impacted the cells by developing localized hotspots at a temperature level close to 50 °C. Often cracks are named microcracks or µcrack, and all typically indicate a fracture in the solar cells in the range of mm to as small as in micrometres. Both terms usually suggest the same type of cracks where partially fully isolated areas are developed in the solar cells mainly due to mechanical or thermal stresses4. This stress can result from manufacturing, transportation phase to the PV site, installation process, or heavy snow and physical damage to the modules. Optimizing these processes can reduce cell cracking; cracks during production are unavoidable.In recent years, cracks in solar cells have become an important issue for the photovoltaic (PV) industry, researchers, and policymakers, as cracks can impact the service life of PV modules and degrade their performance over time5. This is the case because the reduced thickness makes it easier to develop extra mechanical stresses in the cells when assembled into a full-scale PV module. Often, this will cause cracks in the cells and lead to up to 2.5% power degradation in 60-cell PV modules if they do not insulate cell areas. In a relevant study6, cracks have been proven to impact the surface structure of the solar cells and extend to damage the fingers and busbars. This would lead to disconnecting cell areas and reducing the maximum generated current. In the recent work by8, they have shown that solar cell cracks can not only isolate parts of the cells but also, and due to the nature of the cracks themselves, they can develop a localized increase in the temperature, resulting in what is commonly known by "solar cell hotspots".The crack issue in solar cells becomes worse as the thickness of the wafer is being reduced12. These techniques work under the same principle by adding a switching element with high frequency to control the current in the modules and do not affect the interconnection between the module and the power converter. These techniques were approved effective, and they can increase the PV modules output power.The mitigation of solar cell cracks has not been yet discovered. However, as cracks lead to hotspots, there were some attempts to mitigate hot spotted solar cells by utilizing a power electronics device to regulate the current into the affected cells14. A high electric potential difference between the cells and the module farm may be induced in the modules, typically at the PV string level. This phenomenon will result in a leakage current flow from the module frame to the solar cells, which results in a potential induced degradation (PID)17. Therefore, solar cell cracking and PID are different; however, both lead to a drop in the output power of the modules.The PV modules are usually connected in series for grid-connected PV systems to build up the voltage output, and the modules frames are grounded for safety purposes20. In Fig. Cracks are often invisible to the bare eye; the current standard cracks detection method uses Electroluminescence (EL) imaging23, cracks can degrade the PV output power under controlled indoor testing; these various studies, however, do not consider the influence of the size of the cracks and the correlation between the cracks and their thermal impact on the PV modules. In addition, some other recently published work25 has shown that PV cracks can influence the electrical parameters of the PV modules, while they did not precisely evidence whether the cracks purely cause this degradation in the module, as PV modules exposed in the filed can be affected by other degradation mechanisms such as potential-induced degradation26, bypass diodes failure, hotspots, or temperature-induced degradation (TID)27.To date, there is still a gap of knowledge in understanding the impact of cracks on solar cell performance, particularly those exposed in the field under different environmental conditions. Usually, and as explained in multiple previous studiesConsidering these research gaps of knowledge, the main contributions of this paper are to provide an understanding of how the output power degradation in solar cells is affected by different sizes of cracks. In addition, the correlation between solar cell cracks and the development of hotspots will also be discussed. Our last contribution is to correlate PID vs cracked solar cells' power losses and resemble their thermal performance.This paper is organized as follows: “2, and peak power 4.72 W.This work explores crystalline silicon (c-Si)-based solar cells affected by different sizes of cracks. The studies cells are made of three busbars, and as provided by the manufacturer datasheet, under standard testing conditions (STC), each cell has an open-circuit voltage To capture the EL images of the examined solar cell samples, we have used the EL imaging setup shown in Fig. The tested solar cell samples categorizing different crack shapes on the distribution and structural defects. The EL images of the tested cells are shown in Table 2, a homogeneity of illumination ± 2 W/m2 at irradiance intensity range 0–1000 W/m2. In addition, the solar cell temperature can be controlled from 15 to 200 °C via the PVcomB software to maintain a specific temperature level during the experiments. A thermal camera is placed on the back sheet of the solar simulator (solar cell holder) to aid the thermal measurements of the examined samples. The camera has a thermal sensitivity of ± 0.1 °C.The solar simulator tested the performance of the cells, and the output power vs irradiance was taken at each analysed condition. The class A + solar simulator, shown in Fig. This section presents our empirical results of the output power measurements, thermal cycling, and PID testing for the examined solar cell samples.2, the temperature of the cells was maintained at STC conditions, 25 °C. The output power measurements taken from the solar simulator is shown in Fig. 2, and for precision targets, we took four different measurements for every irradiance level. Next, we have distributed the measured output power as in histogram .2) and 0.5 Sun (500 W/m2) are presented in Fig. The output power loss is calculated using , where \We compared the results of the output power of the cracked solar cell with the reference cell that has been already operated in the field. Consequently, there should be some additional losses/degradation in the output power anyways.We applied the smallest standard deviation ratio of 10% below or above the mean. This threshold will guarantee all measurements are included in the analysis.Our baseline to consider whether the crack percentage has a significant loss in the output power is confined at − 10%; this value was selected because:According to Fig. The thermal images of the solar cells, shown in Table Even though the cooling mode of the solar illuminator was set up at 25°, the solar cells have not been left under illumination for a long time to ensure that no rapid increase in the temperature occurs. In addition, following this procedure will guarantee that the temperature increase in some of the tested solar cells results from the cracks, not because of the rapid illumination of the sun simulator.The average surface temperature of the solar cells is then recorded using FLIR software and summarized in Fig. Considering the results in Table We have discovered that whenever the crack area increase, it is not necessary to develop a hotspot. A good example is given in Table To further explain this effect, we have considered experimenting with the solar cells' thermal cycle that is close enough to the baseline temperature, 30 °C. Therefore, both solar cell samples with crack percentages of 7% and 46% have been considered. And then compared with the thermal cycle of the solar cell that has a 20% crack percentage, which develops hotspots. Each cell was subjected to a change in the Sun levels , each Sun level (cycle) lasts for 1 min. The variations of the Sun levels ensure that the hotspot develops in the solar cells and certainly impacts the distribution of the heat. As shown in Fig. During the changes of the Sun levels, the average surface temperature was recorded and summarized in Fig. While understanding the results presented in this section, we realized that there might be a substantial similarity between the cracks and the original PID effect in output power losses and hotspots development. This correlation has been investigated, and the analysis is discussed in the next section.29, while solar cell cracking occurs due to thermal and mechanical stresses30. Therefore, this section will present the output power losses of PID affected solar cells; the results will then be compared with the output power losses of the solar cell cracks discussed in the previous sections. This examination will demonstrate that solar cells' PID effect is not as severe as when cracked by 40% or more.It is apprehended that PID is an utterly different degradation mechanism than cell cracking. PID results from a high voltage electric field and sodium Ion migration from the PV module glass to the cells28. This procedure was performed on two solar cell samples that presents no cracks, shown in Fig. The PID test was performed using the PIDcon instrument. We have applied the standard PID testing conditions, where the temperature is maintained at 85 °C, the voltage is set to negative 1000 V, and the PID test ran over 96 hAs we have shown earlier in Table Furthermore, we compared the degree of similarity of the results obtained by the PID experiment against the cracked solar cell samples Fig. . The out21, we have conducted experiments on various solar cells exposed to field conditions, obtaining an accurate estimation and analysis of the precise impact of cracks. Furthermore, we have also considered studying different solar cells affected by different crack sizes (1–58%), which is different from other recent research work31, which only considered studying PV module-level cracks .In this paper, we have presented the impact of solar cell cracks on their output power performance. Unlike some previous research work33.The thermal performance of all examined solar cell samples was also demonstrated. This experiment has indicated that not all cracks can develop hotspots because there is a substantial inactive area in the solar cell; thus, there is an insufficient area to establish a hotspot. For example, we have shown that when the solar cell is affected by crack size between 11 and 34%, it is likely to develop hotspots. This effect is usually ignored when examining solar cell cracks27. However, the actual correlation between cracks, hotspots, and PID has not been yet investigated other than in this paper.Another contribution of this work is that we have presented the results of the output power degradation of two solar cell samples under the PID test. We have then correlated the power losses of the PID test results with the cracked solar cell samples. We have discovered that PID can result in 30% to 40% losses in the output power; this is pretty much the same amount of losses when a solar cell is affected by at least 25% cracks. Our results of the PID effect are similar to previous work35). However, further investigations must explain this critical problem affecting nearly most PV assets in today's PV market.There are still some critical questions to be answered/linked with this research work; an example, how do cracks or hotspots develop over time? This has to be investigated over a long-term period for solar cells operating in diverse environmental conditions rather than simply examining the solar cells under artificial indoor illumination. In addition, we partially understand why/how hotspots' temperature changes over time  or monumental (greater than 46%) crack sizes.We have seen that the PID can degrade solar cells' output power by at least 20% after 96 h of the PID cycle. Compared with solar cell cracks, this is equivalent to a solar cell affected by at least 25% inactive area (crack size).We have studied the impact of cracks on the performance of solar cells investigated under different conditions. The findings are concluded as follows:


Tinnitus is a central auditory disorder in which different processing systems are involved as a network. One of these networks is memory. Previous studies have demonstrated some deficits in various types of memory in chronic tinnitus.The main purpose of the present study was to investigate the semantic memory, which is not yet investigated in the tinnitus population.In this case–control study, 15 subjects with chronic tinnitus and 16 matched healthy controls were included. 40 semantically related and 40 semantically unrelated word pairs were presented to the participants in a counter-balanced fashion. They were asked to make decision about their semantic relatedness. Then the participants’ reaction times and the accuracy of responses were calculated.M = 1034 ms, SD = 0.31) compared to the control group , p < 0.05. However, no significant difference was found for the mean percentage of correct responses between the two groups.Mean of reaction times were significantly longer in the tinnitus group (The current study provided behavioral evidence that chronic tinnitus can affect the semantic memory. Such behavioral outcomes may provide new insights into more research activities in the field of electrophysiology and neuroimaging in the tinnitus population. Tinnitus as an auditory phantom perception refers to the conscious experience of sound in the absence of any external acoustic stimuli.10Such symptoms and problems refer to the involvement of non-auditory areas of the brain which work as a network alongside the auditory cortex, albeit, this co-existing mechanisms are still controversial.14Specifically, the memory system as one of the components of this network plays a significant role in the awareness of tinnitus and tinnitus-related distress.20Among different types of memory, the sensory memory defect in the central auditory pathway has been indexed by the reduction of amplitude and area under the curve of the Mismatch Negativity (MMN) response, an auditory ERP reflecting the neural basis of the auditory sensory memory, in tinnitus population.Semantic memory is another aspect of memory that is the storehouse of a wide range of knowledge acquired through experience, which is not reviewed in tinnitus population yet.28Although the effects of tinnitus on aspects of memory such as the long term memory has confirmed, the semantic memory as a subset of the long term memory has not been specifically studied in tinnitus patients. Moreover, the overlap between brain regions involved in chronic tinnitus and the anatomical regions specialized for the different aspects of semantic processing impelled us to investigate the interplay of tinnitus and semantic memory.The experimental groups consisted of 15 tinnitus subjects experiencing chronic tinnitus for more than 6 months  and 16 healthy subjects as a control group, the two groups were matched for sex and age. None of these subjects had a history of neurological, mental, or otological diseases, head trauma, and alcohol/drug abuse. All subjects had the behavioral pure tone audiometry threshold levels of 25 dB HL or less at octave frequencies of 250–2000 Hz and not more than 40 dB HL in frequencies of 4000 and 8000 Hz. All participants were monolingual, native Persian speakers. Having normal cognition status was another inclusion criteria measured using Persian version of the Mini-Mental State Exam (MMSE).α = 0.93 for semantically related pairs; α = 0.92 for semantically unrelated pairs; and α = 0.94 for all items). These pairs of words were presented to the participants in a counter-balanced fashion.Stimuli included 40 semantically related and 40 semantically unrelated prime-target word pairs, which are known as the semantic priming paradigm.In a quiet room, the participants heard the word pairs through loudspeakers in free field in the following order: (a) the presentation of the prime word; (b) a silence gap for 1150 ms; (c) the presentation of the target word; and (d) a silence gap for 3000 ms for participants’ response. Then the participants were told that they were going to hear two words in each trial. At the prompt, they should make a decision whether there is a semantic relationship between these two words or not. To show their semantic judgment, they would press left-click on the mouse for the semantically related pairs and right-click for the semantically unrelated ones as soon as they hear the second word. It is necessary to mention that the recorded words were given to the participants using presentation software. The intensity level of stimuli was typically adjusted to the individual's Most Comfortable Level (MCL).All the procedures performed in this study were in accordance with Ethics Committee of Iran University of medical sciences and its later amendments or comparable ethical standards. All participants had been given a written informed consent for their participation. After completing their participation, patients who declared a need for getting more help were referred to the tinnitus clinic to benefit from the treatment programs available in our country.During the experimental task, the Reaction Times (RTs) as an indicator of processing efficiency were obtained for semantically related and unrelated pairs separately. To this end, the RTs were calculated from the onset of target word until the mouse button was pressed by participants. According to a defined default in the presentation software, if participants pressed the mouse button before the offset of the target word, the presented item would not be accounted as a response. Lastly, mean percentages of correct responses also obtained for the related and unrelated condition.t-test (significance level of 0.05) was used to compare the RTs between the tinnitus sufferers and the control group, both for semantically related and unrelated pairs. Moreover for the accuracy of responses, the percentage of correct responses obtained through each stimulus type (the related and unrelated pairs) was also analyzed by independent t-test. The Statistical Package for Social Science  was used to perform all statistical analyses.Firstly, normality of distributions of the data was examined by calculating the standardized skewness and kurtosis index. Values varied from −2 to 2, indicating that the data distributions did not differ significantly from normality. Thus, an independent p > 0.05). In addition, the results of TQ and THI questionnaires represented the tinnitus subjects as a homogeneous group. A summary of participant characteristics is given in As previously mentioned, the current study consisted of 15 tinnitus patients and 16 healthy subjects having been matched in aspect of age, gender, HADS and MMSE score (t-test was conducted to compare the RTs between the two studied groups. As shown in p < 0.05). Furthermore for the semantically unrelated pairs, a significant difference was seen in the mean of RTs in tinnitus subjects compared to the control group (p < 0.05).In the following, an independent t-test. The high correct-response rates revealed that the two groups paid attention to stimuli and task and did not differ significantly in making a judgment about the semantic relatedness of the word pairs. No significant differences were seen between the two studied groups for all the word pairs (p > 0.05). The responses’ accuracy was also compared by independent The main aim of this study was to investigate semantic memory in patients with chronic tinnitus. To this end, the semantic priming paradigm was used as a behavioral tool for studying semantic memory. For that, the accuracy of responses and the speed in the identification of semantic relationship which is indexed by the RT were calculated.41Regarding the main purpose of the present study, the results of comparison of RTs between the studied groups should be taken into consideration. This experiment demonstrated that the tinnitus subjects significantly responded to our stimuli later than the control group, whether they are semantically unrelated pairs or not. This increment in RTs can be an indication of the deficit in semantic memory. In other words, the more difficulty in semantic processing, the more increase in the RTs. It seems that the overlap of regions involved in tinnitus and semantic processing leads to defective semantic processing in tinnitus sufferers. According to Martin, 2001, the prefrontal cortex is one of the neural structures that has an important role in retrieving, maintaining and selecting semantic information.On the other hand, the longer RTs in tinnitus subjects can be a result of their poor performance in the process of integration of the target word with the prime word. As mentioned above, the semantic prime paradigm was used in this study. According to semantic processing, the presentation of the prime word leads to activation of the long-term semantic memory. When the prime word is retrieved, it should be held in short-term memory so that the target word can be integrated with it.Considering the high percentage of correct responses, it appeared that all subjects were attending to the stimuli and task. Accordingly, it can be concluded that the longer RTs in chronic tinnitus patients have not been due to their inattention and distraction.On the other hand, the tinnitus patients had been homogeneous lyselected from the aspect of mental state, tinnitus loudness, and tinnitus annoyance. Moreover, the results of the HADS questionnaire revealed no depression in the tinnitus group. As depression can be associated with disrupted memory for positive materials and enhanced memory for negative materials,The current study indicated a possible deficit in semantic memory in tinnitus subjects. In this regard, tinnitus sufferers revealed poor performance in using meaningful context to activate semantic memory. The longer RTs were a confirmation of this report. Although the study had reached its purpose, it is suggested that the experiment be conducted with a larger group. To confirm the results of RTs, the structural and functional studies can be used for investigating semantic processing in chronic tinnitus.The authors declare no conflicts of interest.


It realizes the maximum speed of 815 mm s–1 on ground and 171 mm s–1 on water. The robot, actuated by the RFH‐modules based on vibration‐driven locomotion mechanism, exhibits the merits of miniature structure and fast movements, indicating its great potential for applications in narrow amphibious environments.Amphibious robots can undertake various tasks in terrestrial and aquatic environments for their superior environmental compatibility. However, the existing amphibious robots usually utilize multi‐locomotion systems with transmission mechanisms, leading to complex and bulky structures. Here, a miniature amphibious robot based on vibration‐driven locomotion mechanism is developed. The robot has two unique rigid‐flexible hybrid modules (RFH‐modules), in which a soft foot and a flexible fin are arranged on a rigid leg to conduct vibrations from an eccentric motor to the environment. Then, it can run on ground with the soft foot adopting the friction locomotion mechanism and swim on water with the flexible fin utilizing the vibration‐induced flow mechanism. The robot is untethered with a compact size of 75 × 95 × 21 mm A miniature amphibious robot actuated by dual rigid‐flexible hybrid modules is developed. It adopts the vibration‐driven mechanism for amphibious motion, with running motion by the friction locomotion mechanism and swimming motion by the vibration‐induced flow mechanism. The robot achieves a compact size with the integration of control system for no transmission mechanisms. According to different locomotion mechanisms, the existing amphibious robots can be generally divided into legged amphibious robots, wheeled amphibious robots, spherical amphibious robots, tracked amphibious robots, snake‐shaped amphibious robots and so on. Since the amphibious robots need to hold the ability to realize dual locomotion modes adapting to different environments, they are usually equipped with two types of locomotion systems or utilize complex transformable structures. Currently, the combination of different terrestrial and aquatic locomotion mechanisms provides a successful pattern to realize amphibious motion, but some disadvantages of each original mechanism are always inherited. Moreover, the associated transmission mechanism and switching structure between different locomotion systems are usually needed for the combination idea, leading to problems of complicated control scheme, complex structure, and difficulty in miniaturization. Most amphibious robots are over 200 mm in length by now, while some typical micro amphibious robots are achieved via special materials but the control system cannot be integrated. Amphibious robots of small sizes are necessary in some cases such as the exploration of narrow passages or caves in the swamp or coast environments. Thus, an integrated amphibious locomotion mechanism to simplify the structure and achieve the miniaturization is urgently required for the amphibious robots.Amphibious robots have unique advantages in the circumstances of environmental reconnaissance, information monitoring, resource exploration, and disaster relief2, 3 which makes it difficult to achieve power integration and restricts the miniaturization. The electromagnetic actuators can be directly powered by low‐voltage supply, thus it is convenient to be integrated and further realize a large motion range. Some products have already been commercialized, such as HexBugs . The existing electromagnetic actuated robots mostly adopt inertial locomotion mechanism of eccentric motors, in which an inertial mass with periodic motion is used to achieve the locomotion for the asymmetric resistance with environment. However, there is usually a backward motion in one period, so that the efficiency is not satisfying, and the speed is not fast. Furthermore, the vibration‐driven mechanism is mainly used for terrestrial micro‐robots currently, whereas effective vibration‐based aquatic locomotion mechanisms are still rare. Some oscillation based aquatic robots on water surface have been developed recently, but these locomotion mechanisms cannot combine with the existing terrestrial locomotion mechanism conveniently. According to the existing works, vibrations in fluid can induce directional movement of the fluid clusters, leading to the generation of flow. This vibration‐induced flow phenomenon is rarely used but has great potential for vibration‐based aquatic locomotion. It can be induced by the longitudinal vibrations such as the acoustic stream formed by the dissipation of sound wave, while it can also be induced by the transverse vibrations such as the flows appeared with the Faraday waves when fluid vibrates in vertical direction.Vibration‐driven locomotion mechanism allows for flexible structural design and is convenient to realize a compact structure for the advantage of no transmission mechanism. The vibration‐based micro‐robots can be realized by piezoelectric actuators, dielectric elastomer actuators, or electromagnetic actuators. The first two actuators usually require complex excitation source to generate specific signal with high voltage or high frequency,24 whi the eccentric motor can generate elliptical vibration on the soft foot, then crawling motion on the ground is realized by frictional force. As for aquatic motion, we investigate the vibration‐induced flow mechanism of flexible plate on water surface and propose a vibration‐based aquatic locomotion method inspired by the directional flow of vibrating block and the movement of honeybees. This RFH‐module offers significant advantages in achieving a miniaturized and hermetic design of amphibious robots, for the vibration‐driven principle does not require transmission mechanism or joints. The robot prototype achieves the integration of control system with size of 75 × 95 × 21 mm3 and weight of 35 g, and it can realize multiple forms of untethered motion in amphibious environments through the cooperation of two RFH‐modules. Thus, for the advantages of small size and flexible locomotion modes, it can serve for the exploration of small caves and slits, as shown in FigureIn this work, we design a unique rigid‐flexible hybrid module (RFH‐module) for achieving the amphibious motions by the vibration‐driven locomotion mechanism. The RFH‐module, adopting an eccentric motor as core unit, can excite the soft foot and flexible fin to realize dual locomotion modes of running and swimming, respectively. As for terrestrial motion, it adopts the friction locomotion mechanism, similar to our previous vibration‐driven crawling robot,26 the2FigureThe appearance of the amphibious robot is designed in reference to the stingray, and the overall size is ≈75 mm × 95 mm × 21 mm, as shown in In particular, the RFH‐module consists of one transmission leg and two driving components, as shown in Figure The two RFH‐modules are connected to the main body via soft silicone to avoid vibration coupling, which is also used to seal the connections. This soft connection can help to prevent vibration from being transmitted to the main body, thus, the two RFH‐modules can vibrate independently. In fact, this vibration isolation design is critical to ensure effective motion of the robot; otherwise, the robot would move randomly as the vibration coupling.The internal part of the robot is the hardware of the control system, and it is mainly divided into three layers: the bottom layer is a rechargeable lithium battery for power supply, the middle layer is a DC motor driver and a Bluetooth low energy module, while the upper layer is a STM32 micro control unit.In addition, as the flexible fin is supposed to vibrate on the water surface according to the aquatic locomotion mechanism, the water level line should be just below the lower surface of the flexible fin, which is achieved by adjusting the structure of the robot and has been illustrated in detail in Note 3The amphibious robot adopts the friction locomotion mechanism by the elliptical vibration of the soft foot for terrestrial motion, and it achieves the linear and rotational motions through the cooperation of two RFH‐modules.FigureF(t) is the centrifugal force varied with time, F0 is the amplitude of the centrifugal force, m is the mass of the eccentric rotor, d is the eccentric distance, ω is the angular velocity. The direction of the centrifugal force is outward along the line connecting the mass center of eccentric rotor and the rotational center O. The horizontal and vertical components Fx and Fy of the centrifugal force are given as:The core unit of the RFH‐module is the eccentric motor, as shown in ω; and the angular velocity is positively related to the exerted voltage, as well as the vibration frequency f  is the amplitude distribution function of the plate in vertical direction, ω is the vibration angular frequency.The flexible plate has a thin thickness and a low stiffness, resulting in obvious deformation when vibrating on water surface. Different vibration modes can be excited under different frequencies, which lead to complicated variations of surface flow fields. We first perform wet modal analysis and harmonious response analysis on the flexible plate to obtain vibration shapes under different frequencies, as shown in v of the plate can be derived as:Then the vertical velocity q is:ρ is the density of fluid.Thus, the velocity component in vertical direction of the fluid clusters in contact with the plate should be consistent with the vertical velocity of the plate, so the fluid dynamic pressure The fluid clusters in adhesion layer of the flexible plate are stimulated by the deformation to obtain different dynamic pressures. The fluid clusters near the antinodes of the edges get larger vibration velocities along vertical direction, and the fluid will be pushed both downward and outward. Considering the momentum equation and energy dissipation in incompressible viscous fluid, the antinodes will obtain lower pressures in the transverse direction of the fin, while the fluid clusters near the nodes have higher pressure likewise, which leads to a pressure gradient and fluid movement along the transverse direction. Thus, the fluid will flow from the nodes to the antinodes at the edges of the plate, and the variants of the theoretical flow fields under different vibration modes are represented in Figure The first natural frequency of the flexible plate is 17.76 Hz according to the simulation Figure , and it Asymmetrical deformations of the plate appear during the transitional state from the first to the second mode and also from the second to the third mode, due to the unilateral constraint and exerted force, as shown by the harmonic response simulation in Figure For the third mode of the plate, the deformation at the middle of the end edge is larger than that of the two sides, as shown in the vibration shape of Figure In summary, the flow field of the first mode is too weak as the low voltage and small vibration amplitude, and the flow fields around second mode are decentralized as transverse flows, while the third mode can gather water effectively in a wide frequency range at higher voltage. The fluid surface will be completely broken if increasing the voltage further, and water will be sprayed backward violently at the end edge of the flexible fin, thus producing a superior driving effect . The friction locomotion segment at high voltage exhibits good linearity, and it decreases as the voltage decreases. However, there is an interesting phenomenon when the voltage is lower. The speed will decrease and approach to zero rapidly as the voltage is reduced to ≈1.5 V, the robot can only perform back and forth motion in situ although the eccentric motors still work steadily  adjusted voltage on the two RFH‐modules. The linear speed of the robot versus voltage, as well as the motion trajectories on the ground, can be obtained by the frame superposition method in a series of motion movies. As shown in –1 at the voltage of 3.0 V. The trend of rotational speed curve is basically consistent with the linear speed and shows linearity in friction locomotion segment. However, there is a little deviation between the clockwise and counterclockwise rotational speed curves due to the differences of the two RFH‐modules. Similar phenomenon as in linear motion experiments appears when the voltage gradually decreases. The rotational speed quickly drops to zero as the robot reaches the switching state of two locomotion mechanisms at ≈1.5 V and cannot produce effective motion; then, the robot switches to the inertial locomotion mechanism when the voltage is further reduced, and it rotates reversely without changing the rotational direction of motor. The reverse rotational speed can reach to a peak of ≈1.7 rad s–1. It should be noted that this reverse motion is expected motion motivated by inertial mechanism according to the analysis in Note The robot achieves rotational motion by setting one RFH‐module still and exerting voltage on the other one , in which the maximum sampling frequency was 392 kHz and dynamic resolution was 5 nm. The sampling frequency was chosen as 5 kHz, which was ≈25 times the maximum frequency of the eccentric motor. Two orthogonally placed laser displacement sensors collected signals at the end of the RFH‐module simultaneously to get the vibration displacement in horizontal and vertical directions, respectively, and then the obtained signals were synthesized further to obtain the vibration trajectory.This experiment aimed to investigate and verify the influence of vibration modes of the flexible plate on the surface flow field. One rigid and one flexible specimen were designed respectively to perform the experiments, as shown in Figure Due to the fast movement speed and wide motion range for terrestial motion, the frame superposition method was adopted to obtain the motion trajectories from motion movies and calculate the speed. During the measurement of linear speed, the eccentric motors were calibrated in advance in case of the differences in characteristics between motors, and the exerted voltage on each motor was adjusted by PWM signal. The maximum voltage was applied first and then the voltage was gradually reduced to obtain a series of motion movies and calculate the movement speed under different voltages. During the measurementof rotational speed, the voltage on one RFH‐module was kept zero, and the voltage on the other RFH‐module was gradually reduced to avoid the influence of locomotion mechanism switching. In this case, the robot rotated with the static driving foot as center and the total width of the robot as radius to draw a circle. While dealing with the motion movies, one point on the robot was chosen as the marker to obtain the motion trajectories, and several movement durations were selected separately to calculate an average speed. As for the rotational motion, several markers on the robot were fitted to a circle to obtain the rotational center and calculate the rotational speed. For the experiment of crossing obstacles, different layers of tapes were pasted on the ground to obtain a gradient increasing obstacle height, and the height unable to overrun prevailed. As for the aquatic motion, the basic method was the same as the terrestrial motion experiment except that the measurement was carried out in a specially designed water tank. The motion movies at different voltages were shot and analyzed subsequently by frame to obtain the motion trajectories and the speeds.n) for each statistical analysis was n = 3. The data were expressed as mean ± SD (Standard Deviation). Statistical analysis of the data was performed using OriginPro 2021b.The sample size (The authors declare no conflict of interest.Supporting InformationClick here for additional data file.Supplemental Movie 1Click here for additional data file.Supplemental Movie 2Click here for additional data file.Supplemental Movie 3Click here for additional data file.Supplemental Movie 4Click here for additional data file.Supplemental Movie 5Click here for additional data file.Supplemental Movie 6Click here for additional data file.Supplemental Movie 7Click here for additional data file.Supplemental Movie 8Click here for additional data file.


The specific aims of the study are to assess whether the amount of time a cytology learner spends reviewing slides correlates with increased diagnostic competency and to determine whether time spent reviewing slides immediately after the multi‐head sessions correlates with a higher level of proficiency. The paper also seeks to explore the impacts of the time of day at which slides were reviewed on diagnostic learning outcome.Data obtained through the cytology laboratory screening logs were reviewed, and the number of hours per day and the times of the day at which the students were present at the glass slide library were tabulated and compared against each of the seven‐unit slide exam scores in the semester to explore possible relationships.r = 0.29) between the number of hours students spent in the laboratory reviewing cases and competency. When the students' unit diagnostic test scores were classified into low and high categories for each test, there was a significant correlation (P = 0.008) between a lack of time spent screening slides in the lab and the number of times a student was ranked at the bottom of the class. Our data do not support a recency effect nor a difference in test scores between those who reviewed cases in the morning vs in the afternoon.There was a positive linear relationship (Cytopathology: The aims of this study are to assess whether the amount of time a cytology learner spent reviewing slides correlates with increased diagnostic competency, and to determine whether time spent reviewing slides immediately after the multi‐head sessions correlates with a higher level of proficiency. The paper also seeks to explore the impacts of the time of day at which slides were reviewed on diagnostic learning outcome.While educating and training a strong cytology workforce may be challenging, our study provides new insights and sheds light on the importance of spending time reviewing slides, and provides guidance for struggling students on how best to improve. Inside this month’s  Boxplot of Bottom of Class for the Exam vs Time Spent in Glass Slide Library. Providing a competent cytology diagnostician with good morphology skills is a vital role that educators play to ensure that the future of the pathology workforce is strong and able to meet the future demands of the profession.The traditional perspective is that the path to success and attaining competency lies in exposure to the material, including reviewing what was taught in class within a 24‐hour time frame to reinforce the memory curve for what was learned.This paper seeks to assess whether the traditional perspective, that perseverance will reap rewards, still holds in cytology education by reviewing the laboratory logs and finding out if there is a correlation between the number of hours spent in the glass slide library looking through the microscope and achieving diagnostic competency, as measured by slide test scores. The use of unknown case slide exams as proxy markers for cytomorphology competency is widespread in cytopathology training and can serve as a good indicator for diagnostic competency.1.1Chronobiology is the study of biological rhythms and its influence on performance, and this subject has been gaining attention in recent years in healthcare practices, from when to perform a procedure like a colonoscopy, to how time of day influenced the abnormal detection rate of cytology screeners in laboratories.We suspect, given the better detection rates from the various diagnostic procedures and screening tests, that students who spent time in the morning reviewing slides at the laboratory should also achieve better competency in the form of higher slide test scores. Despite past studies on the topic, there is little research focusing on the training of cytologists and looking at this from the perspective of chronobiology. The aim of this study is threefold:  To asses2n = 9) and occurred between September and November 2021. As the first‐year students came into the cytology lab to access the facility's glass slide library, they recorded the date, the time at which they entered the lab, the time at which they exited the lab, the number of slides/cases reviewed, and any issues they may have experienced into the facility log binder. The completed logs for the months of September through November, representing all the unit slide tests for the class, were accessed to reconstruct the relationship between the number of hours the students spent reviewing glass slides on their microscope and the corresponding slide test result for the weekly units. A total of seven slide competency tests were given during the semester, corresponding to the seven major units in the gynaecological diagnostic cytology course, ranging from the morphology of benign cellular changes and infectious agents to malignant squamous and glandular lesions and their corresponding precursors. To assess the relationship between time spent and test score (objective 1), each student's weekly results for the seven slide tests and the number of hours spent in the laboratory reviewing morphology were plotted and then analysed using the non‐parametric Spearman rank correlations. A similar analysis was also performed comparing the number of slides reviewed against test scores. According to the Shapiro–Wilk test of normality and a visual inspection of the histogram, time spent is not normally distributed (P = 0.001). Moreover, since the sample is small with a few outliers, the non‐parametric Spearman rank correlation was used instead of the Pearson correlation. All self‐reported times calculated from the logs were isolated for each unit review only and were not cumulative.The student data were obtained through the student laboratory screening logs that were kept as part of the cytopathology laboratory's education quality assurance and control protocol (IRB Study ID# 2021002516). The study sample included all first‐year cytology students .To evaluate the influence of specific slide reviewing habits, specifically whether studying slides within a 24‐hour period following a multi‐head session is related to improved morphological competency (objective 2), the Spearman correlation was performed, comparing time spent reviewing within the 24‐hour period and test scores. According to the Shapiro–Wilk test of normality and a visual inspection of the histogram, time spent studying within 24 hours (recency) of the session is not normally distributed (am and ‘1’ was given for pm. A contingency table for time of day (am/pm) with bottom‐of‐class (yes/no) was created, and a chi‐square test was subsequently performed to appraise the relationships between the variables. All statistical analyses were performed using SPSS version 28 (IBM), and significance was assumed at P < 0.05.Finally, to assess whether the time of day at which slides are reviewed affects test results and competency (objective 3), data was split into morning and afternoon, using 12 noon as the cutoff, where ‘0’ was assigned for 3R = 0.292, P = 0.020) between the number of hours students spent in the microscopy laboratory reviewing cases and their competency, represented by their test scores  of students achieving test scores greater than 80% who did not spend any time reviewing slides within the 24‐hour period following the lesson at the lab. There is no relationship between immediate reinforcement, as defined by a review within 24 hours, and test scores . It is interesting to note that 7 students scored over 80% with no reinforcement, with another 5 scoring over 80% with reinforcement.In Figure df = 1, n = 46] = 1.623, P > 0.05). In looking at the weekly average scores for those who studied in the morning vs the afternoon, the morning cohort appeared to be just a few percentage points higher in test numbers 2, 5, 6, and 7 but lower in number 4  may have impacted the power of the study to draw conclusions. Finally, the time period over which the study was conducted, one 3‐month period between September and November, may have introduced inadvertent seasonality biases as well.This study has several limitations. First, the results are based on students self‐reporting and are prone to error, either inadvertently or deliberately. Second, the retrospective review is focused on gynaecological cytology and may not be generalizable to all types of courses. Third, the emphasis of the study is on the relationship between time spent, study habits, and subsequent competency at the unit test score level, so little demographic information was obtained. Fourth, the small size of the sample (5Despite the limitations, we believe our results to be informative and to have important implications for providing insights into how best to implement morphology learning. First, it reiterated the importance of spending time in the laboratory for the development of competency in the subject. Second, it provided hope for the cytology students who may be struggling by demonstrating that if you can allocate time to reviewing study‐sets, you are less likely to end up at the bottom of the class. In sum, educating and training cytologists so that they are equipped with a strong foundation in morphology may be challenging, but with the right message, on the importance of putting in the hours in the microscopy lab, the challenge can be overcome.The author has no conflict of interest to declare.Paul Z. Chiou: Conceptualized and designed the study, evaluated data, interpreted results, and wrote the manuscript. Yuane Jia: Evaluated data, interpreted results, review, and edited the manuscript.


Within its 2 week period, the Oktoberfest attracts around 6 million visitors yearly to Munich, Germany. Due to alcohol intake, congested halls, and disorderly activities, numerous accidents occur. Although many hand injuries are observed, the impact of Oktoberfest on severe hand trauma injury frequency is under investigated.Data from the regional emergency medical service (EMS) was analyzed over a 9 year period regarding the frequency of severe hand injuries during the world’s largest fair and compared to the corresponding period in the years 2020 and 2021 where the event was cancelled due to the world-wide COVID-19 pandemic. Additionally, we compared the patient numbers during the same period in one Emergency Department of a level-1-trauma and hand trauma center located close to the venue.An exploratory description is made from data collected over a 9 year period (2013–2021) with focus on hand injuries before, during and after the “Oktoberfest”. A total of 4017 hand injuries were allocated to hospitals by EMS. There was an increase in severe hand injuries by 66% during the 2-weeks-Oktoberfest-period compared to years where the Oktoberfest did not take place. Pre-pandemic statistics show an increasing severe hand trauma frequency of 57.5% in September, compared to EMS-referrals during the remanding year.The risk of injuring relevant structures of the hand during Oktoberfest is extremely high as compared to other parts of the body due to beer stein and fall-associated injuries. These injuries can lead to lifelong impairments. Our data are the first that quantifies and pinpoints the risk of severe injury to the hand during Oktoberfest and therefore, it is of great interest for visitors, hand surgeons, paramedics and emergency department healthcare workers.The online version contains supplementary material available at 10.1007/s00402-022-04745-2. Hand injuries affect all demographic sectors of current population and have considerable socioeconomic impact in severe cases. Severe hand injury has consequences not only in regard to profession, but in almost all areas of life, including simple household tasks and leisure activities. Therefore, underestimating severity of hand injury can lead to an irreversible disablement. It is crucial to make a correct injury assessment at first patient contact and moreover to sharpen attention for these injury patterns. Often, clinical training in hand examination is very poor, so that in emergency departments where there is no hand surgeon on site, it is common for injuries to be underestimated or misdiagnosed. Although it is well-known that hand injuries are one of the most common reasons for presentation in a surgical Emergency Department (ED). Unfortunately, there is only few data in literature. Therefore, obtaining data of health care research is also politically of great interest. Referral figures via emergency medical service (EMS) do not reflect the total numbers, as the majority are self-referrals .ED visits have certain peaks throughout the calendar year. Well known is the increase in visits, for example, during New Year’s Eve or boxing holidays . A uniquOn a national and regional aspect, it is important for optimizing infrastructure and on an international aspect our data represent the risk of hand injuries for everyone while visiting a festival.There is an overall increase of all ED referrals due to heavy drinking during Oktoberfest, thus we aim to analyze in which way the resulting amount and characteristics of hand injuries were affected compared to the rest of the year . During With our presented data, we also want to highlight the high risk for visitors suffering from a beer stein injury resulting in potential lifelong disablement, due to injury of relevant functional structures of the hand.2 and approximately 1.8 million inhabitants. The IVENA system collects basic information  and medical specialty, triage category, medical transportation system and estimated time of arrival) and allocates the patient to a hospital, depending on proximity, availability and required resources  [Since 2013, the web-based IT system “IVENA”   is implemented to coordinate all hospital referrals via a Central Command Centre in Munich. The area covered by the Munich EMS (and thereby IVENA) includes around 1000 km center) . When a For the analysis of the frequency of severe hand injuries, a retrospective analysis of data collected by IVENA ehealth from 1 February 2013 to 31 December 2021 was performed for all adult persons, that had been recorded as hand trauma by the EMS independent of insurance status. All cases that were referred to the hospital by paramedics were classified preclinically as “severe” hand trauma and required a medical transportation system. The term “severe hand injury” is considered to be so severe for the patient that he or she cannot get to the emergency room independently. It can be either a bony or deep soft tissue injury, most of them open and with severe bleeding. We then focused specifically on the time span during the 2 weeks of Oktoberfest before lockdown (years 2013–2019) and within the span of the pandemic (2020 and 2021) and compared additionally a 2 week period before and after the Oktoberfest regarding hand trauma cases.For an exemplarily description of the quantitative development of hand injuries during Oktoberfest, we analyzed data of hand trauma injuries of a level-1- trauma hospital and hand trauma center  which is the closest hospital located next to the venue. Therefore, a retrospective analysis of patients’ medical records and the documentation software of the emergency department  was performed to identify all surgical patient admissions and all hand injuries during official Oktoberfest time according to each year. All surgical patients  from age 18 and all types of admissions  were included in this study. The daily hand trauma frequency was additionally calculated for a 2 weeks before- and after-period and were compared to the Oktoberfest period for the “Oktoberfest years” (2018–2019). Additionally we analyzed the most common types of injuries  that presented during Oktoberfest.t test (student’s test) or a Mann–Whitney U test were used after testing for Gaussian distribution. A p value of < 0.05 was regarded as statistically significant and results are presented as the mean ± standard deviation (SD). Graphs were designed with Microsoft Excel and GraphPad Prism 8 .The study was reviewed and approved by the Institutional Review Board of the medical faculty of the LMU Munich under the registration number 20–258 and was conducted in accordance with the Declaration of Helsinki. All data were imported to Microsoft Excel  for further analyses. Descriptive statistics were used for the calculation of the rates and means for the IVENA data. For statistical analyses of the hospital data either an unpaired A total of 4017 hand injuries were allocated to hospitals by EMS in a 9 years observation period from 2013 to 2021. Hand surgery ED admissions have continuously increased but showed no statistical linear function over the study time period from 2013 to 2019  years for male and 51 ± 23.6) years for female patients. Peak age for the occurrence of a hand injury was found to be in 20- to 29-years-old patients  and September (due to Oktoberfest) were excluded for calculation of the average number of hand surgery referrals per months, there are 329 patients with hand injuries admitted to hospital by EMS in Munich. The highest number of hand surgery EMS admissions regularly occur in September with a total of 481. That means an increase of 46.2% in September compared to average referrals of the rest of the year  which is located closest to the venue. Figure p = 0.0031) and after period (p = 0.0003) could be found  and contusion (21%) of the hand. Amputations, tendon injuries and isolated vessel injuries were occurred with a small percentage of 4, 2 and 1% Fig. .Fig. 8MHand injuries are known to be one of the most common surgical presentations in ED. However, the frequency of hand trauma in preclinical EMS is under investigated. The web-based IVENA system, that was implemented in 2013 to coordinate all hospital referrals in Munich provides a unique opportunity to analyze the prevalence and demographics of severe hand trauma throughout the year(s), with special attention to the Oktoberfest and COVID-19 pandemic.Our analyses of a 9 year period 2013–2021) of data of IVENA system concerning numbers of hand injuries made up a total of 4017 out 1,164,586 total emergency referrals cases, providing a first percentage (0.35%) on frequency of hand trauma in preclinical EMS in Munich. Clearly, there is a huge gap between the number of preclinically registered hand injuries and the frequency in ED, where earlier studies from the United States and Germany found hand and wrist trauma the second most common diagnosis 3–2021 of. HoweverConsidering the demographic data of IVENA-registered patients, males were significantly more likely to experience a severe hand or wrist trauma, accounting for 76% of EMS-referrals in Munich during the observation period. Overall, we found male adults aged between 20 and 39 years the most frequent demographic, revealing similar results as described in a retrospective national analysis of ED visits in the United States . PreviouOktoberfest marks a special highlight in the calendars of Munich’s first responders and ED employees. A recent IVENA-based study by Ghada et al. calculated an additional daily admission of 78 patients during Oktoberfest in the years 2014–2018 . Within To further evaluate the effect of the Oktoberfest on the workload and capacity of a single ED and hand trauma center, we analyzed the numbers of all surgical trauma and hand trauma admissions for a hospital that is located 1 km close to the Theresienwiese, where the event is held. For the analysis, we compared the 2 weeks before and after the event for the years 2018 and 2019. The analyses of the daily hand surgery patient frequency in the ED during Oktoberfest in comparison with a 2 weeks before and after period in non-pandemic years revealed a significant increase in hand injuries during the event. By elimination of a COVID-related bias, through the exclusion of pandemic years, the effect of the Oktoberfest on hand injury frequency as observed in preclinical IVENA data, becomes also apparent for the clinical hospital data. In summary, during Oktoberfest the frequency of hand trauma increased by 66% in EMS and by 28% in the exemplary level-1 hand trauma center closest to the venue.The analysis of the injury pattern Fig.  showed tWithin Munich three Hand Trauma Centers are located that provide care for the vast majority of complex and severe hand injuries. Therefore, the increasing frequency of severe hand trauma during the fifth season leads directly to increasing patient volume and predicted chance for emergency hand surgery in those centers. Interestingly, the overall number of hand injury related EMS- and self-referrals decreased during the 2 week period following Oktoberfest to a significantly lower number that was reported for the 2 week before period. Possible explanations for this trend could be a weather-related decrease of sports and recreational accidents in October compared to August and early September. Furthermore, Oktoberfest marks the end of summer in Munich, which is followed by a significant reduction in social and physical activity as the population returns to a normalized day to day pace.This study has several limitations. First, data from January 2013 and February 2013 are incomplete, as these months were enrollment months and thus the system was not activated city-wide. Second, all admissions that were transported by the EMS ambulance are counted. In general, it is often difficult to correctly assess the severity of injury preclinically even for experienced paramedics. Sometimes it only becomes apparent during surgical exploration. We included only patients who were initially identified as hand injuries by the responsible paramedics. All other referrals were not included; therefore, it can be assumed that our results are rather below the real values. Within the evaluation of IVENA, no further basic data on the patients was collected, therefore no statement can be made on the actual severity of the individual emergencies. The evaluation does not provide any information about the further course of the patients. Data on the type of discharge or the inpatient course is not available. Third, as stated above, we drew a comparison between two time periods in years where Oktoberfest took place in 2020 and 2021 when it was cancelled due to the pandemic. However, one must not forget that during the pandemic phase not only the Oktoberfest did not take place, but the entire social life was shut down, so that the general risk of injuries in certain areas decreased. A simplified summery of regional restrictions during that time period can be found in the supplementary.In our data more than 4000 hand trauma injuries were analyzed. In the current literature, there is a lack of hand trauma data. This is the first long-term report of the necessity and use of EMS for hand trauma in a metropolis. Data of hand trauma from a single center is rarely published, but data for an entire metropolis is not available. Moreover, to our knowledge, no work in the literature exists that focus on the incidence of hand trauma during special circumstances like the 2 week time period of the worlds famous fair “Oktoberfest”. We provide data of a 9 year period that shows a clear increase in hand injuries during this period. Although there is knowledge of the increase in injuries in general during the Oktoberfest, there is a lack of valid data portraying this specifically for hand injuries. With the new data, we want to highlight and draw attention to the annual predictable increase in hand trauma injuries, and at the same time encourage hospitals to prepare their emergency departments sufficiently in advance for this small, but predictable wave. Additionally, we want to emphasize that during a festival that concerns 7 million people every year, there is a high risk of severe hand injury. This implies the significant impact of this event concerning the healthcare system. We want also draw attention to all visitors, especially that of the young male individuals, to be careful and attentive while drinking and dancing on benches and holding a heavy beer stein in their hand, as carelessness can lead to lifelong disablement. Another benefit of the published data is improvement of knowledge and awareness of paramedics regarding hand injuries. To implement this on site, we are organizing training courses by hand surgeons to ensure that paramedics recognize a severe hand trauma injury and knows when to refer to a hand trauma center to prevent severe and irreversible disabilities.Supplementary file1 (DOCX 15 KB)Below is the link to the electronic supplementary material.


Many complications in physiology are associated with a deviation in flow in arteries due to a stenosis. The presence of stenosis may transition the flow to weak turbulence. The degree of stenosis as well as its configuration whether symmetric or non-symmetric to the parent artery influences whether the flow would stay laminar or transition to turbulence. Plenty of research efforts focus on investigating the role of varying degrees of stenosis in the onset of turbulence under steady and pulsatile flow conditions. None of the studies, however, have focused on investigating this under oscillatory flow conditions as flow reversal is a major occurrence in a number of physiologic flows, and is of particular relevance in cerebrospinal fluid flow research. Following up on the previous work in which a The online version contains supplementary material available at 10.1007/s10237-022-01579-0. A stenosis refers to obstruction in a blood vessel or an anatomical segment like the subarachnoid space, spinal canal or respiratory airway. A stenosis can induce turbulence and flow separation in the blood vessel or the anatomical segment as a result of adverse pressure gradients. The presence of turbulence can eventually lead to secondary complications to the physiology in question. The onset of turbulence itself is likely to be influenced by the degree of stenosis itself as well as the nature of the flow, whether steady, pulsatile or oscillatory. For example, stenoses in the carotid arteries are well known risk factor for ischemic stroke  namely the circulation of the cerebrospinal fluid (CSF). Another purely oscillatory flow is the airflow in the respiration system. In a purely oscillatory flow the underlying factors that trigger turbulence, the distribution of turbulence in various parts of the cycle, as well as the stabilization mechanisms are different than those from a steady or pulsatile flow with no reversal component. Earlier experiments by Hino et al.  for the DNS of this study as the method scales well on parallel computers—allowing for accurate capture of transitional flow characteristics. The LBM when setup properly Jain  is a verThe geometry of the stenosis was adopted from the experiments of Ahmed and Giddens  shown i. Stenosiequally extended by 12 vessel diameters to account for the reversing nature of the flow, which resulted in a total pipe length of approximately 26 diameters. Due to flow reversal, the fluid travels equally on both sides of the stenosis throat, and the location of stenosis in the pipe is thus expected to influence the onset of transition as well as propagation of formed turbulent bursts.Similar to previous study Jain  the pre  A and blowing and suction stages respectively in the following.The oscillatory nature of the flow can be described by the Womersley solution with a negative  component. The Womersley solution for laminar, pulsatile flow through rigid tubes is defined as: T/6 where flow quantities were analyzed. Like the studies of Jain  in Dresden, Germany. Extensive development and use of the solver for applications in physiology is done at the University of Twente, The Netherlands.The adaptable poly engineering simulator (APES) framework  relaxation scheme was sufficient. The BGK relaxation parameter was set to D, of 1 unit, the spatial resolution order of polynomial or resolution in space for other higher order methods like the spectral methods. We employed the D3Q19 stencil of the LBM in this study, which means that each lattice cell had 19 degrees of freedom. In higher order methods, the order of the polynomial allows for a higher accuracy within a cell, which is not the case with LBM. Thus these resolutions cannot be compared with those employed in similar studies  had about 9000 lattice nodes for computations thereby reducing the communication to computation ratio to an optimal minimum, and ensuring fully efficient utilization of compute resources.Our previous works Klimach et al. , Hasert The Netherlands. In case of a transitional or a turbulent flow, it is always challenging to decide how many total cycles should be used for ensemble averaging until the quantities are statistically converged as the compute costs and physical details need to be balanced. Ideally, the ensemble average should attain the shape of a laminar flow, similar to inflow or the turbulent fluctuations should wash out from the averaged plot.Simulations at Reynolds of 2000 and 2100 are only reported in this work due to the laminar nature of the flow at lower Reynolds numbers. The simulations for all the cases were first conducted for only abort criteria was set in Musubi to stop the simulation upon achievement of a steady ensemble average. Thus, each subsequent cycle was ensemble averaged with the previously computed cycles and when the velocity fluctuations in ensemble averages vanished, the simulations were stopped automatically. This analysis revealed that a total of about Due to the lack of this information a priori, we first simulated the flow with pulsation frequency Karlsson  reports Karlsson .u is the instantaneous velocity at a particular lattice site, x denotes the spatial coordinates, t is the time and T is the period of cycle.A total of We assumed that turbulence was the only source of fluctuations in the flow and composed the velocity field into a mean and a fluctuating component. This is known as Reynolds’ decomposition and is commonly used for steady flows. The oscillatory flows have a reversal component in addition to the pulsating nature of the flow. Triple decomposition  is derived from the fluctuating components of velocity in 3 directions as:The frequency components present in a transitional or turbulent flow can be analyzed from the power spectral density (PSD) of the TKE. The PSD was computed in this work using the Welch’s periodogram method, which was related with Kolmogorov’s energy decay to observe the inertial and viscous ranges.In the previous Jain  as well The Kolmogorov scales are defined as spatial and temporal scales when viscosity dominates and the TKE is dissipated into heat Pope .D are computed from the fluctuating component of the non-dimensional strain rate defined as:The Kolmogorov scales, non-dimensionalized with respect to the velocity scale The Kolmogorov length, time and velocity scales are then respectively computed as:Based on these scales, the quality of the spatial and temporal resolution of a simulation is estimated by computing the ratio of The entclass1pt{minimaThe flow at udy Jain  of \docuClearly the fluctuations at These findings are further elaborated in the power spectral density (PSD) plots of Fig. x–z bisecting plane in the eccentric stenoses cases of all variants and oscillation frequencies. The observation point P3 Supplementary material 2: Vorticity in the axisymmetric case with 60% stenosis and pulsation frequency w2 (MP4 13101 kb)Supplementary material 3: Vorticity in the axisymmetric case with 60% stenosis and pulsation frequency w1 (MP4 11951 kb)Supplementary material 4: Vorticity across the x-z plane in the eccentric case with 60% stenosis and pulsation frequency w1 (MP4 9778 kb)Supplementary material 5: Vorticity across the x-z plane in the eccentric case with 60% stenosis and pulsation frequency w3 (MP4 14491 kb)Supplementary material 6: Vorticity across the x-z plane in the eccentric case with 60% stenosis and pulsation frequency w2 (MP4 13308 kb)Below is the link to the electronic supplementary material.


We read with interest the study published in the recent issue by Woller and colleagues,It is well known that the standardization and harmonization of D‐dimer testing are poor, and fibrinogen equivalent units (FEU) and D‐dimer units (DDU) are the two units commonly used to report D‐dimer levels. However, there is a huge difference in D‐dimer results between these two reporting systems.Additionally, the details of the D‐dimer assay in Woller's study were not described clearly. We speculated that it would be an FEU reagent since the ULN is 0.5 μg/ml, which should be declared in the paper. Furthermore, the authors should also provide the analytical performance of the D‐dimer assay because it is important for readers to know the potential statistical bias of the predictive model. We suggest that the authors refer to the recommendations from a previous official communication  from the ISTH Scientific and Standardization Subcommittee on fibrinolysis.The authors declare that they have no conflicts of interest regarding this article.LZ and XL drafted the manuscript, and ZZ participated in discussion and critical editing of the manuscript.This work was supported by the Hubei Provincial Nature Science Foundation of China (2020CFB865) and 2020 Wuhan Young & Middle‐age Medical Backbone Training Programme.