The advent of laparoscopy marked a fundamental change in the evolution of medicine. The procedure progressed consistently after the first time it was performed in a human being nearly a hundred years ago. The 1960's and 1980's witnessed groundbreaking changes. During this time, laparoscopy evolved from a purely diagnostic procedure into an independent surgical approach. Outstanding pioneers of the times were Palmer, Frangenheim and Semm. Laparoscopy advanced rapidly and influenced gynecology as well. The procedure was initially attacked most vociferously by the surgical fraternity. However, within a short period of time the pendulum shifted: laparoscopy became the preferred surgical approach for a variety of diseases—whether benign or malignant—in several medical disciplines. Laparoscopy has become a routine approach in the twenty-first century. Technical advancements have led to robot-assisted surgery. Future developments will include artificial intelligence and augmented reality. In the present article we address past milestones, current practices, and future challenges in laparoscopy. Primum non nocere. Possibly, the Hippocratic impulse underlying the demand for moral action on the part of doctors was one of the many factors responsible for the introduction of minimally invasive surgery as we know it today. Surgeons and physicians have been consistently focused on minimizing the risks and complications of surgery.Endoscopic procedures have become an integral part of all surgical specialties and are now a standard approach in all fields of surgery. An increasing number of complex surgical procedures are performed by the laparoscopic approach. The generation of the 2000s takes laparoscopy for granted. Conventional laparoscopy has been extended to include robotic-assisted surgery. In fact, we are on the verge of implementing artificial intelligence and augmented reality in laparoscopy –3. The hGeorg Kelling was the first to describe the basic principles of endoscopy of the abdomen. Kelling performed the procedure in a dog –8. AlmosThe first laparoscopic appendectomy was performed by Semm on 13 September 1980 at the department of obstetrics and gynecology, University of Kiel , 9, 10. In a letter written in 1981, the President of the German Society of Surgery urged the German Society of Obstetrics and Gynecology to revoke Semm's medical license. The fact that a gynecologist wished to show surgeons how to perform an appendectomy was simply inconceivable. Semm had exceeded a limit that was considered impassable until the time. However, he was cognizant of the immense potential of laparoscopy not only in gynecology but also in surgery, and persisted in his unwavering efforts to minimize surgical trauma for patients , 9.The rapidity of this development had a significant impact, especially on gynecology. Entirely new pathways could be broached after the introduction of laparoscopy in hysterectomy, uro-gynecological interventions, and oncological surgery, including lymphadenectomy in different compartments of the body. Laparoscopy became firmly established in other specialties as well, such as surgery and urology.The increasing complexity of the interventions was accompanied by significant demands on surgeons and technological equipment. A surgeon comes close to his physical and mental limits when performing endoscopic operations for several hours .The subsequent development of endoscopy was closely linked with technical advancements. The aim of laparoscopic interventions such as NOTES , or surgery performed through a single trocar (single-port technique) is to reduce access-related trauma by further minimization of the skin incision.Robot-assisted surgery is the most dynamic form of minimally invasive surgery in our times. Better visualization of the field of surgery by means of 3D technology and extension of surgical instruments to 7 degrees of freedom permit the use of minimally invasive surgery even in complex situations. Robot-assisted guidance of the instruments enables the surgeon to work without tremor and with a low level of fatigue, which is very useful for surgeons as well as patients during complex interventions. Moreover, the surgeon is able to work simultaneously at two consoles. The learning curve is shortened, complication rates are reduced, and training in surgery is fostered .The introduction of endoscopy in surgical practice is one of the greatest success stories in the history of medicine. As far as the development of minimally invasive options is concerned, there is still no end in sight.This report provides a historical overview of laparoscopy from its early beginnings to current times.Endoscopy is derived from Greek and means “viewing the inner spaces of the human body” (“endo” and “skopein”). In addition to the usual investigation methods of palpation, auscultation and percussion, the very first written records of medicine bear evidence of the fact that doctors were always interested in the possibility of “looking into” (endoscopy) the human body .Hippocrates II , the principal representative of the school of Kos, described the use of a speculum for investigation of the rectum (Albukasim (912-1013 A.D), an Arabian physician, was the first to use reflected light to view the inside of the body. He held a glass mirror in front of the vulva and thus reflected light into the vaginal vault . Cardan Philipp Bozzini (1773–1809), a doctor in Frankfurt, played a significant role in the development of modern endoscopy because he marks the transition from ancient to modern medicine . In 1806Antonin Jean Desormeaux 1815–1894) advanced this historical development in 1843 with the creation of the first portable endoscope . Antonin–1894 advIn 1901 Georg Kelling 1866–1945), a surgeon and gastroenterologist from Dresden, demonstrated the first laparoscopy at the end of his lecture entitled “About the inspection of the esophagus and the stomach with flexible instruments”; he referred to the technique as “coelioscopy” 6–1945, a, 8. At tNine years later, the Swedish internist Hans-Christian Jacobaeus 1879–1937) introduced the term “laparothoracoscopy” during the first endoscopic inspection of the human chest and abdominal cavity (79–1937 iThe first laparoscopy in the USA was performed by Bertram M. Bernheim (1880–1958) in 1911. He named his method organoscopy , 21. TheInsufflation of the abdominal cavity was improved. One day after the end of the First World War, a treatise on X-ray diagnosis of the abdominal cavity was published in the Munich Medical Weekly. Otto Goetze 1886–1957), an assistant surgeon and author, focused on radiological problems. He used oxygen to improve contrast on X-rays . In orde57, an asLaparoscopy became increasingly well-known and its application spread far and wide. The existing knowledge had to be summarized in a textbook. Roger Korbsch published the first textbook on the subject in 1927 .Optics were also improved. Heinz Kalk 1895–1973), a gastroenterologist from Berlin, known as the founder of the German school of laparoscopy, developed a 135-degree lens system and a double trocar . Kalk F used lap–1973, a Apart from significant progress in equipment and technology, the surgical spectrum was widened as experience with the technique increased. In 1933, Carl Fervers succeeded in performing the first laparoscopic adhesiolysis, which may be regarded as the first surgical laparoscopy in the current sense of the term .In 1937, the American J.C. Ruddock reported on more than 500 laparoscopic procedures with biopsies, mainly obtained from the liver. This internist, who published his work in surgical journals, used pincers supplied with electrical power for the purpose of coagulation. Notably, Ruddock was the first to report a substantial number of complications with the technique .A further milestone in the historical development of laparoscopy was achieved by the Hungarian internist and pulmonologist János Veres (1903–1979), who introduced his insufflation needle which had, in fact, been described earlier by Goetze but had slipped into oblivion. Veres developed a special canula with a spring mechanism. Its purpose was to create a pneumothorax in order to treat tuberculosis, which was a widespread disease at the time . Even toThe first minor surgical interventions were performed in the sixties of the twentieth century, primarily by gynecologists. Raoul Palmer (1904–1985), a gynecologist from Paris, made notable achievements in this regard . Palmer Since the abdominal access was difficult because of the blind nature of insertion, in 1946 the American Albert Decker (1895–1988) introduced the laparoscope transvaginally through the posterior vaginal vault and named the procedure culdoscopy. However, the diagnostic procedure was inadequate from this perspective and the technique, which was initially rather widely accepted, became less popular in the USA .The development of laparoscopy in Germany after the Second World War is primarily linked with the names of Hans Frangenheim (1920–2001) and Kurt Semm (1927–2003) . FrangenThe Kiel University Department of Obstetrics and Gynecology under Kurt Semm (1927–2003) is regarded as the birthplace of modern laparoscopy. He became the most productive researcher and innovative instrument maker in the field of modern endoscopic surgery .In the 1960s, two decisive developments paved the way for a new era in endoscopy. The British physicist Harold Hopkins 1918–1994) developed the Hopkins optics in 1961 and achieved a further milestone in the field . This op developeHowever, a large number of gynecologists and surgeons criticized Semm for his “keyhole surgery” and believed that, thanks to modern anesthetic methods, laparotomy was no longer a problem. According to these critics, Semm had exaggerated the problem of adhesions which, they believed, could be easily resolved by open laparotomy. Some physicians treated Semm's reports of the new spectrum of endoscopic options  with disbelief, and asserted that Semm started an operation as a laparoscopy and ended with a laparotomy . Semm meTwo German surgeons, Gotz and Pier, pursued Semm‘s purpose and established laparoscopic appendectomy on a wide basis. Already in the early 90's, they performed hundreds of appendectomies by this approach and perfected the technique. They even used it in patients with acute appendicitis .In 1985, the German surgeon Erich Mühe (1938–2005) performed the first laparoscopic cholecystectomy using the instruments developed by Semm . In 1987However, there was still vehement opposition. Hans Troidl, then senior surgeon at the University Clinic of Surgery in Kiel reported that, at the 107th Congress of the German Society of Surgery in Berlin in 1990, an article on the first 100 laparoscopic cholecystectomies initially submitted and published by him was suddenly struck off from the official Congress program .A video presentation of Semm's laparoscopic appendectomy at a gynecologists' convention in Baltimore in 1988 encouraged McKernan and Saye to perform the first laparoscopic cholecystectomy in the USA. They used Semm's instruments in combination with laser technology . Later oAdvances in other fields of medicine delayed the subsequent evolution and application of laparoscopy. The development of laparoscopy was ignored by many surgeons in the 1970's and 1980's. The reasons were innovations in anesthesia and intensive medicine, and the new spectrum of medications which enabled surgeons to perform prolonged operations. Endoscopic cholecystectomy and appendectomy were considered daredevil artist's surgeries that offered risky solutions to safely resolved problems. The notion that major medical problems call for major solutions such as abdominal incisions was deeply ingrained in the minds of surgeons. The fundamental concept of laparoscopy was contrary to this notion .In contrast to general trends at the time, a group of German surgeons founded the Surgical Task Group for Endoscopy and Ultrasonography in 1976. Five years later, the Society of American Gastrointestinal Endoscopic Surgeons (SAGES) was founded in the USA.The first issue of the journal Surgical Endoscopy was published in 1987 and the first World Congress of Surgical Endoscopy was held in 1988. The convention was a major success and is regarded as a global breakthrough in laparoscopy .The British urologist John E.A. Wickham (born in 1927) was the first to use the term “minimally invasive surgery” and attracted significant attention when he published his visions about endoscopic procedures in 1987 in the British Journal of Urology . AlthougIn 1987 he predicted the paradigm shift in practical surgery that took place a little later: “Surgeons applaud large incisions and denigrate “keyhole surgery.” Patients, in contrast, want the smallest wound possible, and we at Britain's first department of minimally invasive surgery are convinced that patients are right” .In the early 1990s, literally overnight endoscopic surgery was welcomed by widespread acceptance and rapid dissemination. This “laparoscopic revolution” was triggered by a sudden demand from patients, and its popularity heightened by avid media interest . The chaThe problem of imparting the knowledge and skills of endoscopy had been addressed for a long time. A breakthrough was achieved by the so called pelvi trainer , developThe introduction of electronic elements in the operating room . Th. Th40). Viewing the transformations in surgery along with innovations in supporting medical specialties such as anesthesiology and intensive medicine, infectious diseases, pathology and others, it is almost disconcerting to note that illustrations of human anatomy, a basis for all medical specialties, were available in similar excellent quality 120 years ago and were by no means inferior to current visual presentations of human anatomy  or access via a single trocar (single-port technique). Based on findings in pelvic neurofunctional anatomy and the introduction of laparoscopy in the dissection and visualization of the pelvic nerves Marc Possover introduced the concept of “Neuropelveology” in clinical practice. In 2014 the International Society of Neuropelveology was founded .In an age of increasing specialization in medicine, the interdisciplinary approach is gaining importance and offers opportunities for endoscopic surgery . Thanks The disadvantages include the high cost of installation and maintenance in robot-assisted procedures, which usually involve long operating times at least at the beginning and are associated with a renewed learning curve even for experienced laparoscopists. Furthermore, doctors as well as nursing staff must be trained in the use of the robot system , 50. DocWe await the coming decades of development in medical technology with a tear in one eye and a smile in the other. With a smile because medicine and patient care will benefit from rapid global technological progress. With a tear because we do not know whether the original essence of our existence, namely exercising our manual skills on human beings, will be abolished in the near future.IA, DF, UM, LM, JP, NM, MB, GG, and AL contributed equally to the formation, writing, and editing of this manuscript. All authors contributed to the article and approved the submitted version.The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. The handling editor RW declared a past co-authorship with one of the author IA.All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.


In this paper, we describe the needs and specific requirements of the aerospace industry in the field of metal machining; specifically, the concept of an edge-computing-based production supervision system for the aerospace industry using a tool and cutting process condition monitoring system. The new concept was developed based on experience gained during the implementation of research projects in Poland’s Aviation Valley at aerospace plants such as Pratt & Whitney and Lockheed Martin. Commercial tool condition monitoring (TCM) and production monitoring systems do not effectively meet the requirements and specificity of the aerospace industry. The main objective of the system is real-time diagnostics and sharing of data, knowledge, and system configurations among technologists, line bosses, machine tool operators, and quality control. The concept presented in this paper is a special tool condition monitoring system comprising a three-stage  set of diagnostic algorithms designed for short-run machining and aimed at protecting the workpiece from damage by a damaged or worn tool. Rapid digitization is changing societies around the world, including how we communicate, what we buy, how we live, and how the production system works. For the first time in history, digital technologies have connected more and more industries with numerous societies, and therefore are influencing the volume and quality of production as well as the functionality of products. Industry 4.0 has resulting in leading IT solutions in all aspects of production, enabling the ordering of specific products and entire related value chains. This involves the need to link production and logistics including storage, service, energy supply, linking networks of suppliers, etc. . An important element of Industry 4.0 is cyber-physical systems (CPS) that use the Industrial Internet of Things to integrate new production organizational methods which results increased product personalization and production processes that require less participation of operators. An example of the architecture for implementing a CPS is presented in ,3.A practical example of a CPS is replacing the manual delivery of components in a production line with automated guided vehicles that transport components to the appropriate production cells. The use of RFID tags on manufactured products enables machine tools to automatically select a set of tools for a particular product, achieving full personalization of production and reducing the minimum production lot size to one piece. Another example is the use of the Industrial Internet of Things (IIoT) technology to implement a wireless sensor network in a plant that can monitor production, detect anomalies, such as vibrations, or even energy consumption by machinery and technological installations ,4,5. By With the development of new technologies, it is becoming increasingly common to support or replace traditional methods for supervising production processes with computerized and automated methods. Therefore, an important element of an Industry 4.0 system in a manufacturing factory is the production line supervision system which minimizes defects, increases the repeatability, optimizes machining conditions, and reduces failure rates and downtime of machine tools, resulting in increased machining efficiency, while reducing costs. In turn, supporting supervision of a production process improves utilization of the machinery park (including planning of repairs), achieves better control of the production process, and minimizes the time required for documenting the process. Cutting edge wear diagnostics (end of life detection);Detection of catastrophic tool failure (CTF);Diagnostics of the shapes of metal chips;Detection of excessive vibration;Others (built-up edge and collision detection).There are many commercial systems that perform TCM tasks ,7,8,9,10Tool condition monitoring (TCM) systems have been designed as commercial systems by manufacturers such as Montronix, Nordman, Artis, and Digital Way ,8,9,10.Manufacturers offering commercial diagnostic systems, or their components, have solved the problem of measurement sensors quite well. Sensors are available for cutting forces and related quantities such as torque or power consumed by drives, acoustic emission, and vibration, which have measurement ranges suitable for the cutting process and are immune to conditions in the cutting zone ,8,9 tablStudies have been conducted that used very sophisticated methods for tool condition monitoring ,13,14,15Support vector machine (ν-SVM) for prediction of different tool wear states ;Radial basis function-based kernel principal component analysis (KPCA_IRBF) and relevance vector machine (RVM) for a tool flank wear predictive model ;An adaptive time window and deep bidirectional long short-term memory neural network for prediction of the tool failure zone in milling ;A deep learning method based on multiscale feature fusion by parallel convolutional neural networks for tool wear prediction ;An Ellipsoid ARTMAP (EAM) network model based on incremental learning algorithm for recognizing the wear states of milling tool ;An HMM algorithm and multilayer perceptron (MLP) for accelerated wear ;Recurrent neural networks for tool wear in turning .Various methods of integration have been used for diagnostics based on determined features. The most common are the following artificial intelligence methods:A more extensive review of such methods can be found in .There is a large discrepancy between strategies used in commercial systems based on single signals and laboratory strategies based on signal integration with results that are much more reliable. The main reason for this discrepancy is the low level of automation of laboratory algorithms. Developers of these algorithms perform many steps “manually” selecting, for example, signal segments for analysis, features, or neural network parameters for the analysis of a specific machining task. Although more efficient than before, the use of such an algorithm in a commercial system requires the operator to have considerable knowledge of diagnostic systems and there is a significant amount of work required to start each new production, which is not accepted by industry .Another issue is that the TCM is a time-critical system. Especially, catastrophic tool failures need to be detected within milliseconds or faster. Therefore, not every type of supervision system can be connected directly to the cloud, and therefore sometimes edge computing is a better solution .Today’s diagnostic systems are versatile and are used in a variety of industries that use machining, such as automotive, engineering, and shipbuilding. Each of these industries has its own specific production and the expectations from the diagnostic system are also slightly different. In this paper, we present the aerospace industry’s expectations of a machining process diagnostic system and the concept of a system that could meet these expectations.The needs and specific requirements of the aircraft machining industry for a production supervision system have been identified during the implementation of research projects in Poland’s Aviation Valley, for example, at PZL Mielec (Lockheed Martin Corporation) and Pratt&Whitney Rzeszów ,46. In tDue to the previously mentioned high component costs, the most important aspects are system reliability, accuracy of tool wear estimation, reliable CTF avoidance, and rapid detection even at the cost of many false alarms. Simple diagnostic strategies included in commercially available diagnostic systems are not considered to be effective enough by the aerospace industry; therefore, academic solutions are more effective, but they are still plagued by some problems.An important aspect, as in all other industries, is the ease of use of diagnostic systems. Ideally, the system should be fully automatic. Commercial systems are not user friendly. Many algorithm settings including thresholds, signal segments to evaluate, and various parameters such as delays have to be manually selected by the operator. Machine tool operators have been known to stop using these systems precisely because of the complicated operation and, in this case, most academic solutions are based on custom solutions and not optimized for ease of use; often user interfaces are not developed, only signal processing software. These academic strategies are based on advanced signal processing methods, and often on artificial intelligence methods, which require the selection of many different parameters for their operation. These parameters are selected “manually” by researchers, which make the application of these strategies in a commercial solution even more complicated than current versions.The aerospace industry works in short runs, even a few pieces in a single run. For this reason, the diagnostic system should be ready to operate without, or after learning on, one tool life cycle without the need to tune the system after subsequent tool life cycles, as is often the case in current commercial systems.Another feature of aerospace machining is the large size of workpieces and difficult-to-machine materials. As a result, tool life is often only a few operations rather than hundreds as in the automotive industry. This, in turn, makes it necessary to replace the tool due to natural wear during the operation rather than afterwards. A diagnostic system should indicate the level of gradual tool wear more often than once per operation after completion of the operation, as is the case in commercial systems.In the aerospace industry, there are a large number of components with complex shapes that are machined on five-axis machine tools and it is impossible to install a wired load cell on the table of such a machine. There are several sensor solutions that use radio signal transmission technology, but often a transmitter with a built-in battery is connected to the sensor via a cable (such as the Montronix accelerometer). There are rotary dynamometers from Kistler that can be mounted on a spindle, but they are costly, and several sensors are required for diagnostics. In an industrial setting, this is too expensive and cumbersome. Manufacturing companies still lack proposals for wireless sensors that are small in size and can be easily installed as close to the machining area as possible. In addition, installing diagnostic sensors requires interference with the kinematic structure of the machine tool, such as disassembling the turret of a lathe or dismantling the table of a milling machine. If these are new machines, this can void the service warranty. Therefore, owners of machine tools are skeptical about installing additional sensors. For this reason, new solutions based on power sensors for machine drives are being developed, which do not interfere with the construction of the machine tool and their installation only temporarily takes the machine tool out of production.The aerospace industry requires complete production records for every part, which is not required in other industries. This must include when the part was made, by whom, and on what machine, as well as all measurements of the part. If a system is used to monitor the condition of a tool, then, so are the indications of that system. Therefore, in the aerospace industry, a tool condition monitoring system should be part of a production line flow monitoring system that can collect all this information.Ensuring proper production supervision is particularly needed in the aerospace industry, where full documentation of the manufacturing process for each part is required, including information about who, when, and under what conditions it was manufactured or measured. The proposed concept for such a system is shown in The primary function of the tool condition monitoring and cutting process module is to predict the end of life and to detect catastrophic tool failure (CTF). However, there are autonomous systems that do not cooperate with master systems. A TCM system which enabled such capabilities was built at the Department of Automation and Metal Cutting at Warsaw University of Technology ,45,46,47The operator module allows the operator to fully document the production process of a given component , starting from acceptance of the order, indication of the individual parts to be measured by quality control, recording of the measurement results, commenting on the individual parts, and finally closing the order. In addition, the module provides a list of serial numbers for a given order along with comments, parameters to be measured, nominal values, and acceptable deviations. The module also performs a measurement analysis, i.e., calculation of SPC parameters. The module uses scanners (barcode or QR) to read confirmation numbers and electronic measuring devices that automatically register measurement results, and enables communication between the operator and the TCM system. The operator sends information to the TCM system about cutting edge replacement, and receives information from the TCM system about tool wear status, occurrence of catastrophic tool failure or collision, and sensor status information.The quality control module is used to document measurement results for parameters selected for inspection. It can read the confirmation number and measurement results directly from the electronic measuring instrument tools and scanners. The user of this module can designate a part as defective, quality control accepts measurement orders through this module, and the measurement results are stored in a database.The process engineer module is used for ongoing control of processing results. One such module, running in the technologist’s office, interacts with several operator and quality control module systems installed at different production or inspection stations. The process engineer has access to measurement results from all cells, and therefore can control the stability of the process as well as provide detailed instructions on measurements or processing. Setting TCM parameters is also an important task of a process engineer.The process engineer sends information about the diagnostic settings  to the TCM system, and also assigns individual tools to the machined surfaces on the part. On the basis of this information, the TCM system suggests validation of individual surfaces in the case of high cutting edge wear, defines the machining program according to which part is machined, and makes it available to the TCM system.The process engineer provides the operator with technological settings .A production supervision system cannot function without appropriate data flow between the following modules: TCM, operator module, quality control module, and process engineer module. This is realized by means of a database, The TCM system transmits to the process engineer diagnostic signals, work progress reports, and results of machining process supervision on a given cell .The TCM system sends, to the operator, information about estimated tool wear, occurrence or threat of emergency situations (collisions and catastrophic tool damage), proposals for tool replacement, and estimated number of operations that can be performed at a given tool edge.The TCM operator provides information on tool replacement, and a suitably qualified operator also has the authority to teach the supervision system.The operator provides the process engineer with reports on completed tasks (orders and operations), measurement results, and comments.Quality control sends the measurement results to the process engineer.The TCM system can send suggestions to quality control about measurements at a site, such as when there is high tool wear.As mentioned above, the basic element of the manufacturing process control process is the supervision of the manufacturing process, for example, the cutting process, including the cutting tool. The advantage of a TCM system, which is part of the presented concept, is not only its cooperation with the superior system, but also its autonomy and efficiency in tool condition diagnostics . The elements that determine the effectiveness of a TCM system to the greatest extent are the diagnostic algorithms included in it.Estimation of gradual tool wear (GTW). With a small number of operations in the life cycle, tool replacement may be necessary during operation. Thus, the algorithm must make a diagnosis about the state of the tool much more frequently than once per operation. An example of an algorithm that could be used here is the algorithm presented in [est versus actual ΔT. Currently, the more popular RUL (remaining useful life) ratio is derived from the ΔT ratio according to the formula RUL = 100% − ΔT. The estimation error by the ΔT algorithm is shown as the root mean square error (RMSE). The number of operations per tool life is from seven to ten, and the tool wear estimates are much higher. The solution performs well from about five operations per tool life. Further development of diagnostic algorithms should lead to even lower numbers of operations per tool life, even below one, because such cases also occur in the aerospace industry.ented in . Here, tented in , shown iDetection of accelerated tool wear. Accelerated tool wear (ATW) often precedes the occurrence of catastrophic tool failure (CTF) and detecting it could prevent CTF. The ATW phenomenon is much more dynamic than GTW, therefore, the diagnosis is made much more frequently, at most within a few seconds and the faster the better, for example, the algorithm proposed in [posed in  can be uThe concept of the system presented in this paper includes a three-level system of protection against working with a blunt tool as follows:Detection of catastrophic tool failure. The CTF must be detected in a fraction of a second, otherwise the workpiece may be damaged. The shorter the response time of the system, the lower the probability of this failure. For example, the algorithm developed in [loped in  can be uWith this approach there is a high probability of avoiding machining with a defective tool, which is very important for the aerospace industry.The TCM, presented in this study, uses fully automatic tool condition diagnostics based on multiple signal features for different machining methods and for different forms of cutting-edge wear. Proper communication with the machine tool is required to fully automate the TCM. The proposed set of algorithms for the presented TCM gives the possibility of automatic production completely without, or with limited, participation of an operator.Detection of cutting, i.e., the system automatically recognizes cutting and separates cutting periods into signals from fast feeds, as well as run-up and run-down;Automatic selection of signal segments with a fixed waveform ;Determination of hundreds of signal features from the selected signal segments;Automatic selection of useful features (correlated with the tool condition) and elimination similar features (correlated with each other) for each individual segment ;Determination of the used part of tool life for each feature separately and integration of indications into one evaluation, displayed to an operator as a percentage of tool wear.The tool wear detection algorithms used in the presented TCM system operate fully automatically, without unnecessary involvement by operators and technologists, and even without their knowledge. The developed TCM only requires the operator to mark tool changes. The basis of the algorithms consists of the following steps:Detection of catastrophic tool failure is a separate algorithm that operates in real time. The system detects such a failure within milliseconds and sends an emergency feed stop signal and a tool retract signal to the machine control system.The name of the machining program;Two-state information on the status of operations, i.e., the start and end of the machining program and the start-stop of the working feed with division into individual axes;Information about the values of feed rates in individual axes, rotational and cutting speed, the number of the currently executed block, identification of the currently working tool ;The control system should have eight digital line outputs that transmit information about special functions from the level of the program executed by the machine tool;The control system should have two digital inputs, i.e., one to stop the feed rate and retract from the contour of the workpiece, and one to operate a special function in the machine tool program to wait for a “high” signal to appear at the digital input.For proper and autonomous operation of the system, it is necessary to ensure that this system can communicate with the machine control system to provide the system with current information about machine operating parameters as follows:It is desirable to be able to save the machining program in parametric form so that parameter values  can be corrected by the diagnostic system.The diagnostic system should include a real-time data acquisition and processing module, a data visualization module, and a communication module with the machine tool and access to technological data. The diagnostic results should be available at least locally, however, it is strongly emphasized that, according to the Industry 4.0 paradigm, this is inefficient and the results should be exported to a database or cloud application.The concept of a production supervision system based on edge-computing technology, as presented in this paper, and using a three-level algorithm of the tool estimating GTW and detecting ATW and CTF, would avoid production shortages and increase productivity while maintaining the required production quality. It is tailored to the requirements of the aviation industry, with a focus on minimizing defects in machining of expensive parts made with hard-to-machine materials and high precision requirements, as well as to the specificity of aviation production in which there are small series production and limited operations per one tool life. This system speeds up and minimizes the risk of error in making accurate production documentation and quality measurements of each manufactured part, which is required in the aerospace industry. Full documentation and supervision of the process parameters allows for its certification and a significant reduction in the number of measurements of parts, which contributes to improving the economics of production. The requirements presented in this paper, the specificity of the aerospace industry, and the suggested directions for developing diagnostic systems are the starting point for conducting work on new diagnostic systems in research centers.


The World Health Organization Surgical Safety Checklist was developed to improve communication in perioperative care, reduce mortality and complications of patients, and ensure the consistent use of procedures for safe surgery. Despite the increased awareness of the checklist, the implementation compliance is reported as low and the degree of completeness varies. This study aimed to explore the possible supportive factors for the effective implementation and to identify potential awareness and barriers to its implementation in gynecological and obstetrical operation.A survey using a cross-sectional design that included surgeons, anesthetists, and operating room nurses was performed. We used an online link to distribute the survey to all eligible surgical team members in our hospital. The survey contained various aspects of perceptions on the Surgical Safety Checklist and an open-ended question that allowed respondents to offer their opinions on the topic.The overall self-reported awareness of the checklist within each professional group was high. The awareness of surgeons was lower than that of operating room nurses, particularly in the Time-out section. Most participants believed that operating room nurses ranked the highest compliance to the protocols, while surgeons stayed the lowest. Active leadership with experienced operating room nurses, good training for surgical team members, and simplification of the checklist would be the positive factors for the effective implementation.Although there is a high acceptance and adequate self-reported awareness of the Surgical Safety Checklist, it is not always possible to implement it successfully. Our findings suggest that with experienced and effective leadership, barriers to implementation can be overcome. With positive perception and commitment, the Surgical Safety Checklist is easy to implement and it can make a profound improvement on the safety of surgical care. Moreover, a strategy of repetitive training and assessment on the part of the involved health care professionals may be necessary to further improve patients’ safety during surgery. One of the key elements in the surgical risk management approach to a safer hospital environment is the use of a surgical safety checklist. The World Health Organization (WHO) Surgical Safety Checklist (SSC) was developed to improve communication in perioperative care, to reduce mortality and complications of patients, and to ensure the consistent use of procedures for safe surgery.Surgery is an important treatment option for many gynecological and obstetrical diseases; however, medical errors which occur during the surgery are the main reasons for serious complication developed due to surgery.–6 Improved communication and shared responsibility within the health care teams may contribute to reducing medical error and adverse events.,8 The WHO SSC procedures of 3 sections have been packaged and implemented over 10 years in our hospital to reduce medical errors and improve the prognosis of all patients.The WHO SSC is administrated in three sections: “Sign-in,” “Time-out,” and “Sign-out.” “Sign-in” includes verification of the patient's identity, the surgical procedure and site, and consent before induction of anesthesia. Besides, the known allergy and risk of blood loss are reviewed. “Time-out” includes further confirmation of correct operation on the correct patient and site before the skin incision. There is a review of anticipated critical events, antibiotic prophylaxis, equipment availability, and essential imaging results. “Sign-out” includes the record of the procedure, the completion of the instrument count, and the labeling of specimens before the patient leaves the operating room (OR). Any issues with equipment and postoperative prescriptions and instructions are reviewed. There is increasing evidence that a positive influence on patients’ outcomes is more likely if SSC items are optimized. In the Obgyn operation room unit, there are many emergency surgeries, such as salpingectomy or salpingostomy for ectopic pregnancy and cesarean section for fetal distress, umbilical cord prolapse, placental abruption, etc. Clinical mistakes and errors are more likely to occur in emergency cases because the SSC protocols were not accurately implemented. Moreover, the surgeon acts as the leadership of the surgical team, and the awareness and perceptions of the surgeon are particularly important. It is reported the compliance towards safety protocols of surgeon stays at the lowest level in the surgical team.–12 Thereby, active involvement in the implementation phase, as well as continuous training, is presumed to greatly impact the compliance and acceptance by all health care team.,14Despite the increased awareness of the SSC, the implementation compliance is reported as low and the degree of completeness varies. It is reported that the possible reason for this could be a lack of positive role models or less than enthusiastic team members, hierarchical barriers, limited knowledge of correct usage, and inappropriate implementation procedures.In this study, we investigated the awareness and perceptions of the implementation of the SSC by frontline medical professionals of the department of gynecology and obstetrics in our hospital. This study aimed to explore the possible supportive factors for the effective implementation of the SSC and to identify potential awareness and barriers to its implementation.2All ethical approval and consent procedures were approved by the Medical Ethical Committee of West China Second University Hospital, Sichuan University . We confirmed that all research was performed following relevant regulations and informed consent was obtained from all participants.We surveyed surgical team members’ awareness and perceptions using a cross-sectional design that included surgeons, anesthetists, and OR nurses in Western China Second University Hospital. All participants worked in the central operating unit. This survey had to do with the principle of anonymity, and authors did not have access to information that could identify individual participants during or after data collection. The attitude scales of this survey referred to a previous article about the implementation status of the SSC.The survey contained various aspects of perceptions on the SSC and an open-ended question that allowed respondents to offer their opinions on the topic. The items are listed in Table P < .05 was statistically significant.Statistical analysis was performed using SPSS software. Pearson Chi-square or Fisher exact test was applied to compare the difference in proportions. 3In the central operating unit, 267 staff were invited to participate in the survey. The general characteristics of all respondents are summarized in Table P < .001). Most of the respondents believed that they had an active perception in implementing the SSC in the Sign-in section (Score of 9.58) rather than that in the Time-out (Score of 7.45) and Sign-out (Score of 7.51) sections (P < .001)  of participants believed that anesthetists should be the leader to implement the Sign-in protocol, while 62.5% (167/267) agreed that OR nurses should be the leader in the Sign-out protocol. Interestingly, 40.8% (109/267) and 37.1% (99/267) were certain about both surgeons and OR nurses as the leader in the Time-out protocol  of respondents believed that they would be more likely to comply with the use of the SSC, whereas 15% (40/267) of respondents thought that the SSC caused delays, and 11% (30/267) did not believe it worked. 242 respondents answered the open-ended questions and included their reflections on awareness and perceptions of the SSC protocols and safety issues. Most participants noted that the endorsed implementation of the SSC prevented mistakes in the operation room, such as wrong patient's identity, the uncertainty of correct site, wrong position of the patient, and medication allergy. Besides, some positive and negative factors that may influence the use of the SSC were described , which parallels those of previous studies that showed high levels of awareness of the SSC usage.,18 Most of the respondents were satisfied with the use of the SSC, highlighting the contribution in minimizing surgical errors. This result was found to be following respect to the rate of SSC used and the subjective belief of healthcare professionals. Furthermore, we found that OR nurses showed the highest levels of awareness rather than surgeons, because a large initiator of implementation of the SSC was introduced via OR nurses, who were less autonomous in their scope of practice and were mandated by their clinical managers to use the SSC.Each of the surgical teams in gynecological and obstetrical OR routinely implemented the SSC into their daily procedures. Awareness of the SSC is integral in its successful adoption.,20On the contrary, participants in the current survey noticed that surgeons’ level of awareness was at the bottom, particularly in the phase of Time-out. We found that perceptions towards Time-out protocols were at the lowest level, and 77.9% of participants agreed that surgeons stayed the lowest compliance to the SSC protocols in our hospital. The SSC of Time-out phase was not completed or was left incomplete, because some surgeons did not comprehend the importance of the SSC adoption, and they thought that the checklists have to do with OR nurses’ duties only, therefore they do not need to participate in the completion. Whereas surgeons always complained that the Time-out protocols caused delays in the operation especially on emergency occasions, such as ectopic pregnancy, ovarian cyst torsion, placental abruption, placenta previa with massive hemorrhage, or fetal distress, etc. Previous studies showed that nurses’ and surgeons’ acceptance of the SSC could reveal insufficient equipment standardization and improve cooperation. In this survey, participants believed that both surgeons and OR nurses were the leader in the Time-out section. Even some surgeons waited for the OR nurses to initiate and complete the Time-out protocols before skin incision. Although the growing evidence supporting the SSC use, this study suggested that there were mixed attitudes regarding its utility from frontline medical professionals. 11% of respondents, particularly surgeons and anesthetists, believed that the SSC is unlikely to improve surgical safety in their patient population because they felt the SSC had the potential to distract them from their clinical duties and they were somewhat burdened by the task of completing the SSC. Even when OR staff complied with the components of the SSC, other team members were sometimes obstructive, inattentive, and preoccupied with other tasks, which may reflect a lack of belief in the utility of the SSC. In addition, we noticed that the motivation for completing the SSC appeared to differ from OR nurses and other staff. OR nurses emphasized that the SSC was a mandated protocol and, thus, needed to be completed. Surgeons and anesthetists were more concerned with their clinical tasks. That is why OR nurses always forced surgeons and anesthetists to complete the SSC even in the Sign-in and Time-out section.There is a recognition that an experienced leader in each section of the SSC implementation is necessary, and the leader in the section of Sign-in, Time-out, and Sign-out should be the anesthetist, surgeon, and OR nurse respectively. However, we noticed that if there was an experienced OR nurse who had the primary responsibility for initiating the use of each SSC section, other members tended to be more obedient to the procedures. It is recognized that experienced OR nurses comprehend the cooperation within the whole surgical team is essential. The importance of communication and teamwork had been demonstrated as an integral part of health care provision. Consequently, active leadership is important for the successful application and sustainability of a checklist as well as for regular inspections and feedback.The present study highlighted various factors influencing compliance with the use of the SSC. It was reported that the surgeons and anesthetists were the members of the surgical team who did not fully comply with the SSC implementation or who were the most reluctant to change their behaviors. which suggested that surgeons need to be both supported and trained to elevate the level of compliance. It is reported that surgeons’ level of compliance was strongly related to training on the SSC, and education and training during SSC implementation enabled the surgeons to comprehend the importance of the SSC adoption. In this survey, 1 participant reported that surgeons ignored the Time-out section of the checklist and forgot to perform fallopian tube ligation, which was requested by a patient with pernicious placenta previa during the cesarean surgery. Another adverse event was recorded that gauze was left in the patients’ vagina after laparoscopic hysterectomy causing infection of the vaginal margin because the surgeon and OR nurse did not complete the instrument count in the Sign-out section. The awareness and positive attitudes towards the purpose and importance of the SSC suitably put surgical members in OR. Besides, the attitudes of surgical team members toward the SSC influenced the willingness to participate in training. To achieve better compliance, training should become an integral part of each surgical team and be performed continuously. Therefore, to further facilitate the use of the SSC, we aim to produce a video with proponents. This video is to become an integral part of effective training and to demonstrate good practice, study data, and case studies where the SSC enhanced patient safety. Furthermore, an additional factor reported as hurting the compliance of the SSC adoption was its strange and complex content. It is suggested that the content of the SSC needs to be supported by scientific evidence and to be written clearly, using understandable words preferably embedded within existing processes. Some participants in this survey suggested that the SSC requires simplification in emergency cases to allocate enough time for the operation. Therefore, it will affect the compliance of each professional.It should be noted that the majority of participants reported that the lack of time and training is the most important barrier to complete the SSC. The introduction of the SSC implementation evoked criticism because some surgeons found that the SSC procedure often interfered with the workflow of existing routines and delayed their operation time. They considered that it was a waste of time to answer the questions in the Time-out section before they made the first incision, especially on emergency occasions. Therefore, the subjective compliance of some senior surgeons stayed at a low level, and they were resistant to change their habits when implementing the SSC. Surgeons’ commitment is particularly important to successful SSC implementation,A limitation of the current study was the fact that there was no baseline survey before the implementation of the SSC and it was only conducted over a brief period. We assessed compliance in terms of SSC use; however, we did not investigate the quality of SSC use. The attitudes of health care providers may differ substantially owing to differing baseline perioperative procedures before implementation of the SSC. Therefore, the findings cannot be generalized because this study is susceptible to a professional desirability bias.In conclusion, this study provides information about the current awareness and perceptions towards the implementation of the SSC in gynecological and obstetrical operations. The implementation and sustainability of SSC remain a major challenge. Although there is a high acceptance and adequate self-reported awareness of the SSC, it is not always possible to implement it successfully. Our findings suggest that with experienced and effective leadership, barriers to implementation can be overcome. With positive perception and commitment, the SSC is easy to implement and it can make a profound improvement on the safety of surgical care. Moreover, a strategy of repetitive training and assessment on the part of the involved health care professionals may be necessary to further improve patients’ safety during surgery.We are sincerely grateful for the clinical and statistical assistance provided by Dr Xiaorong Qi, Dr Xi Tan, Dr Han Huang, and Nurse Li Wan from West China Second University Hospital.Conceptualization: Ce Bian, Lingyun Yang.Data curation: Junming Gong.Formal analysis: Junming Gong, Bo Sheng, Lingyun Yang.Funding acquisition: Ce Bian.Investigation: Junming Gong, Bo Sheng.Methodology: Ce Bian, Lingyun Yang.Writing – original draft: Junming Gong, Lingyun Yang.Writing – review & editing: Lingyun Yang.


In Oman, the first liver transplant was performed at the Royal Hospital (RH) in September 2017. Since then, thirteen cases have been operated on at the RH. All of these cases were living-donor liver transplants (LDLT), and the remaining cases were treated in India with a total of approximately 193 recipients. To provide an in-depth overview of donor experiences, challenges, and perceptions, a cross-sectional study was conducted.  A cross-sectional study was conducted at one tertiary hospital in 2019. The survey was designed to collect data composed of closed and open-ended questions to reveal a thorough knowledge of the topic. n = 8/12) who reported that fear of operation is the cause that prevents people from donating are among the male gender, while more men believe that the main cause is lack of knowledge. 90% of the respondents felt satisfied after donation. More men reported ambiguous feelings before donation. Moreover, married donors reported ambiguous feelings before donation (p = 0.008). The younger age group reported anxiety and doubt as a challenge through their donation experience.  A total of 50 of 120 donors responded to the survey with male dominance in the sample (68%) and 64% were aged 28 to 38 years. 66% of the respondents came to know about the donation through hospital staff. Interestingly, respondents ( This study revealed that donors have a positive feeling after donating as they have saved a life, as well as being empowered by family and community. The donors encourage individuals to donate a portion of their liver. Some crucial questions arose, such as anxiety before surgery, ambiguous feelings before surgery, and fatigue after surgery. These findings underscore the importance of a holistic approach that would enable donors to be well informed prior to surgery. Since liver transplant was first performed by Thomas Starlz in 1963 . Living-Donating a portion of one's liver to a family member or close friend is a medical “hero” for the recipient and for the community at large . EnsurinRecent research in New York by Rudow D et al.  showed tIn Oman, the first hepatic transplant was carried out at the Royal Hospital (RH) on September 24, 2017.Since then, 13 patients were operated on at the RH which is all LDLT. All of these cases were LDLT, and the remainder were treated in India with a total of approximately 193. Recipients and donors are initially assessed as part of our national hospital transplantation program. A thorough informed consent process and rigorous medical assessments of donors and recipients are conducted to ensure proper ethical practice and safety.Once deemed appropriate for LDLT, a medical report is sent to the transplant team in India, who will review all the details of the reports and render the final decision for the operation. All individuals who have undergone surgery (donors and recipients) are tracked at RH.In March 2021, the Oman National Transplant Programme for Tissues and Organs was established to organize, develop, and plan the transplant process in Oman. To enhance the donation process in Oman and to obtain detailed information on donor experiences, challenges, and perceptions, a cross-sectional study was performed and discussed in this study.The study was conducted at a tertiary hospital in Oman which performs liver transplants in the country.This cross-sectional study was carried out from November 2019 to January 2020. Since the beginning of liver transplantation in Oman, the total number of donors is 193 for citizens and noncitizens, where some donors are deceased, which is not directly related to the donation. Therefore, the sample size reflected the fact that the total population met the inclusion criteria. Noncitizens or cadaver donors were excluded.The survey was designed in Arabic as the target participants are Arabic speakers. The questionnaire consisted of closed and open-ended questions to reveal an in-depth understanding of the subject. A total of 35 open and closed questions were structured, prompting donors to talk freely and reflect on their experience of donating liver. The survey tool consisted of the following elements: previous knowledge of LDLT; challenges faced by donors and how to overcome them; willingness to donate following death; the justification for LDLT; the psychological and social status of donors after donation; the impact of the donation on the nature of the donors work; acceptable levels of risk; possible donor complications; and support for LDLT from liver transplant team.This survey was commissioned by two field experts who are liver specialists and a research expert from the WHO office in Oman to verify the validity of the content. As the target population is Arabic-speaking, the tool was translated into Arabic by all researchers and then handed over to a native Arabic speaker to verify the translation.The survey was piloted with five donors for validation, which was then generated as an online questionnaire.The online link to the survey was distributed by liver transplantation nurses using the clinic's contact list of liver donors. All donors enrolled in the clinic were provided with the online link and were invited to participate in the study. A one-month period was allotted for complete data collection, and a weekly reminder was sent to all donors via a liver transplant nurse.Descriptive analysis was done to describe the characteristics of the participants such as percentage, frequency, counts of the gender, level of education, and source of income as shown in This study was approved by the Royal Hospital Scientific Research Board under approval number 94/2019. Participants in this study were informed of the objective of the research, and voluntary participation was explained via an online link prior to the questions. In addition, participants were informed through the link that once they clicked on the bottom of the agreement, it is an agreement to participate in the study. In addition, no details were required for the tool for identifying the specific participant. To secure the collected data, all data were transmitted online to the primary author.In total, 50 donors out of 120 have participated in this survey. Males dominated the sample , and 32 (64%) were between the ages of 28 and 38, with no significant gender differences observed. 26 (52%) had a secondary or higher level education, 20 (40%) were unemployed, and the majority of respondents (donors) were the recipient's parent (either mother or father of the recipient) .p = 0.758). However, there is a significant relation to age group  in terms of awareness of liver donation size.Two-thirds of the respondents became aware of the donation through hospital staff, with no significant difference between gender, age group, or relationship to the patient . The majn = 8/12) who reported that fear of operation is the cause that prevents people from donation are among male gender, while more men believe that the main cause is lack of knowledge. The majority of men and older groups disagree that postdonation body image may affect the donor's decision to give. Older groups supported organ donation after death, while younger groups were neutral, with no significant difference in educational attainment (p = 0.084). However, all of them disagreed with higher education.Interestingly, respondents  of respondents agreed that they had prepared the donation transaction well before the donation. However, younger age groups reported better preparation and explanation of potential complications. Men and older adults reported improved preparedness for postoperative pain .In general, most (39.78%) of the respondents reported that they were well supported by family, friends, and health care providers, although some of the younger age groups were neutral in terms of support for health care providers after donation as well as support for family and friends before donation .p = 0.009)  felt satisfied after giving, with the exception of five donors in the youngest age group with different levels of education; however, all those with secondary education were in agreement (= 0.009) . Few donp = 0.008) with no significant difference calculated in relation to the education level (p = 0.153)  .Our study confirmed that liver donation is a good experience for the majority of people. In particular, self-esteem, family and community recognition of generous giving, and the sense of pride in helping a loved one have increased. Furthermore, the study participants were positive for organ donation as a result of death. These findings are documented as the donation is considered to be a positive experience , 6.Based on our study, it is obvious that the majority of liver donors were primarily informed of the donation through the donation clinic and popular media such as Twitter® and whatsApp®. These results are inconsistent with , 8 that Furthermore, since this study revealed a spontaneous decision to donate, it is considered a healthy attitude towards donation. This conclusion is supported by a study in which donors did not feel obliged to make a donation , 7–9. HoAlthough our study confirmed that donors were well prepared before and after surgery, the younger age group, particularly males, reported better preparedness, and this may raise concerns about gender difference and level of education. This confirms the same observation that donors are well prepared and educated throughout the donation process , 7, 11. This study revealed an ambiguous feeling before donation which was more prominent among men. As well, it has shown that young people tend to be more anxious and have doubts. These problems would have prevented individuals from making donations. These could be linked to the lack of adequate counselling or psychological support through the donation process. Moreover, these factors might be a normal feeling as a process of uncertainty during the giving and cares of the loved ones. These results are consistent with others –12.The present study is limited by the number of participants involved in the survey. As well, donors are surveyed by significant postdonation period, which may limit the level of recall of their experience.We conclude that donors have a positive impact after donating because they are happy to save their lives and be self-reliant by encouraging the giving and saving of lives. Some critical problems have arisen, such as lack of effective pain management, fear and anxiety before surgery, and ambiguous feelings before surgery and fatigue after surgery. These findings underscore the importance of a holistic approach that would enable donors to be well informed prior to surgery. The collaboration of psychologists, pain management, the liver transplant clinic, and social workers can assist in addressing these concerns. In addition, we recommend that future researchers conduct a mixed method study that includes an interview and survey to reveal in depth the experience and challenges and compare the predonation process with the postdonation process. As liver transplantation is a new experiment in Oman, we recommend further investigation to explore public perception of organ donation.


Auditory brainstem responses (ABRs) and auditory middle-latency responses (AMLRs) to a click stimulus were measured in about 100 subjects. Of interest were the sex differences in those auditory evoked potentials (AEPs), the correlations between the various AEP measures, and the correlations between the AEP measures and measures of otoacoustic emissions (OAEs) and behavioral performance also measured on the same subjects. Also of interest was how the menstrual cycle affected the various AEP measures. Most ABR measures and several AMLR measures exhibited sex differences, and many of the former were substantial. The sex differences tended to be larger for latency than for amplitude of the waves, and they tended to be larger for a weak click stimulus than for a strong click. The largest sex difference was for Wave-V latency (effect size ~1.2). When subjects were dichotomized into Non-Whites and Whites, the race differences in AEPs were small within sex. However, sex and race interacted so that the sex differences often were larger for the White subjects than for the Non-White subjects, particularly for the latency measures. Contrary to the literature, no AEP measures differed markedly across the menstrual cycle. Correlations between various AEP measures, and between AEP and OAE measures, were small and showed no consistent patterns across sex or race categories. Performance on seven common psychoacoustical tasks was only weakly correlated with individual AEP measures . AMLR Wave Pa unexpectedly did not show the decrease in latency and increase in amplitude typically observed for AEPs when click level was varied from 40 to 70 dB nHL . For the majority of the measures, the variability of the distribution of scores was greater for the males than for the females. This is the third and final report on a large-scale study designed with several goals. Multiple crews of young-adult listeners were tested behaviorally and physiologically for several weeks each. More than three years were required to test all the crews. In , we repoFor this third report, the focus is on the two auditory evoked potentials (AEPs) known as the auditory brainstem response (ABR) and the auditory middle-latency response (AMLR). ABRs and AMLRs are electrical responses from subcortical auditory brain regions, recorded using a set of electrodes attached to the scalp and earlobes. After the presentation of an acoustic click of moderate strength, a series of peaks or waves can be detected using such electrodes. The AEP peaks are traditionally categorized according to their latency following the click; peaks from 0–15 ms are called ABRs, peaks from 15–100 ms are called AMLRs, and peaks longer than about 100 ms are called auditory late responses (ALRs) . The auThe experimental objectives of the overall study were established primarily for the OAE and behavioral measures and then carried over to this AEP segment of the study. There was a hierarchy of questions. At the top were the questions of whether OAEs covaried with psychoacoustical performance and how sex differences and menstrual-cycle differences affected those covariations. Also of interest was whether OAE strength correlated with AEP strength . Because AEPs were to be measured for the latter purpose, it was logical to examine the AEP responses in the same framework as used for the OAE and behavioral measures; namely, to examine the covariation between the various AEP and psychoacoustical measures and to document how sex differences and menstrual-cycle differences affected those covariations. Twenty-two measures of latency and amplitude were obtained, 8 for ABR and 14 for AMLR (detailed below). Having those various AEP measures also allowed an examination of their interrelationships. During the analysis of the behavioral and physiological data, race/ethnicity emerged as a relevant variable, and all the planned analyses were expanded to include comparisons by race .Concretely then, for AEPs the experimental goals were to:Auditory science long has been aware of sex differences in certain AEPs. For ABRs, the typical findings are that the latency of Wave V is shorter in females than males, and the amplitudes of Waves I and V are more robust in females than males e.g., –7). Ther. Ther7])Existing evidence suggests that the sex difference in Wave V does not exist in newborns but does exist prior to puberty , 11. To For AMLRs, past results have disagreed about the existence of sex differences. Tucker et al.  observedA substantial literature exists on the effects of the menstrual cycle on the auditory system, for behavioral measures , for AENote that the basic sex differences in AEPs are not attributable to the menstrual cycle; they exist in life prior to the onset of menstruation and appear to be relatively constant through life. Any menstrual effects are modulations on this basic, permanent sex difference. Just as for OAEs (review in ), the baImmediately upon their discovery , ABRs weWhen planning this study, the expectation was that systematic relationships between OAEs and psychoacoustical performance were more likely to be found than were systematic relationships between AEPs and behavior. The reason was that OAEs are more intimately tied to the cochlear-amplifier system than are brain potentials, and many psychoacoustical phenomena have characteristics that follow cochlear characteristics. Also, the stimuli used to evoke OAEs were more similar to the stimuli used for our psychoacoustical tasks  than weAfter all the behavioral and physiological data were collected, it became evident that race differences interacted so markedly with sex differences for 6 of the 7 psychoacoustical tasks and for OAEs that we were obliged to analyze those data within race as well as pooled over race , 2. For The effects of race are well-documented for OAEs, hearing sensitivity, and noise-induced hearing loss , 31–34. OAEs are measures from the cochlea and AEPs are measures from auditory neural pathways. A reasonable question is whether OAE strength is correlated with strength of any measure of ABR or AMLR. That is, is the strength of the cochlear-amplifier system  reflecteThe question was whether the individual differences in any of the ABR or AMLR measures covaried with the individual differences in any of the other ABR or AMLR measures. Knowing which measures are highly correlated is potentially informative about underlying processes.Many of the various AEP comparisons made across sex, race, and menstrual cycle failed to achieve statistical significance, even some that had been significant in previously published articles. The modern open-science initiative , 30 arguThe emphasis here is on the methods used to collect and analyze the ABR and AMLR data. Only highlights of the procedures used for the psychoacoustical and OAE measurements are included here; additional details are available in , 2.All aspects of this study were approved in advance by the Institutional Review Board of The University of Texas, Austin.Subjects were primarily college students, who were recruited on campus using standard procedures. They were paid for their participation. The average age was 21 years for both females and males, and both race groups. Prior to being hired, subjects were screened for normal hearing and normal tympanometry using standard audiometric devices and procedures ).To assess the reliability of the judge, a pseudorandom sample of 570 waveforms was re-scored while blind to the first scorings. The test/retest correlation was greater than 0.90. Details can be found in section IIsupp.D in psychoacoustical data from those early crews could not be pooled with the psychoacoustical data from the later crews. Because the malfunctioning VM was not used for the physiological measurements, all male subjects could be included for the AEP (and OAE) analyses reported here. For consistency with the two previous reports [After several all-male crews of listeners had been tested, the true rms voltmeter (VM) used for setting the levels of the stimuli for the psychoacoustical tasks malfunctioned (VMm). As a consequence, those early male crews were tested with stronger psychoacoustical stimuli than used for the remainder of the male crews and for all of the female crews; accordingly, the  reports , 2, the A second complication was that information about race was not obtained for some of the males in the Pre-VMm crews. While that is immaterial for comparisons for which the subjects are pooled over race, it does mean that the Ns for the Non-White and White males do not sum to the N for the pooled “all males.” These complications exist out of our intent always to use all of the data possible.One emphasis in our Results section is on the sex, menstrual-cycle, and race differences measured for the 22 AEP measures. Those various pairwise comparisons are summarized using effect size, which was calculated as the difference between the means of the two groups of interest divided by the square root of the weighted mean of the variances of those two distributions. By convention, effect sizes of 0.2, 0.5, and 0.8 are considered small, medium, and large, respectively . Here thThe magnitude of any effect size depends not just on the separation between the two means (the numerator), but also the sizes of the two variances that are averaged in the denominator. As discussed in section IV.G. below, the variances for our AEP measures were generally larger for the male groups than for the female groups, but there were no systematic differences by race. That is, the differences in our effect sizes by race were not the result of race differences in variance.actually obtained effect sizes. To assess which of those outcomes were most unlikely to be due to chance, a resampling technique was used. Specifically, for each pairwise comparison, the scores for all of the subjects in the two groups of interest were pooled, a random sample of scores equal to the N of one of the two groups of interest was drawn, these were viewed as representing one group and the remaining scores as representing the second group, the effect size for this resample was calculated, the process was repeated 20,000 times, the number of times the  a resampled effect size exceed the actually obtained effect size was tallied, and the tally was divided by 20,000. The resulting proportion was taken as the implied significance of the pairwise difference of interest. For some sex-difference comparisons, none of the 20,000 resampled effect sizes exceeded the actually obtained effect size; for those instances, we assigned a p value of < 0.0001. Because our tallies were based on the absolute values of the resampled effect sizes, our estimates of implied significance should be viewed as conservative (“two-tailed”). We have used versions of this resampling procedure in the past [Effect sizes were calculated for a large number of pairwise comparisons. These are called the the past , 43.unlikely to be due to chance; details are in [Additional questions of interest for this study involved correlations of several types: between pairs of AEP measures, between the AEP and OAE measures, and between the AEP measures and performance in each of the seven psychoacoustical tasks. For those comparisons, Pearson product-moment correlations were calculated. Because of our psychoacoustical findings , those cs are in  and sects are in .®  and later were verified using a purpose-written algorithm in LabVIEW®. The Pearson product-moment correlations were calculated using Excel® and an algorithm available in LabVIEW®. The resampling of both effect size and correlations was accomplished using LabVIEW® programs written by author EGP. The levels of implied significance achieved by individual effect sizes and correlations are indicated in the tables using the same hierarchy of symbols for each table. Ns for the various subgroups for each dependent variable are shown in the figures.The calculations of means, standard deviations (unbiased), Ns, standard errors, and effect size initially were made using ExcelIn addition to the systematic measurements of the individual peaks described above, the data for the various subject groupings also were summarized by calculating waveforms averaged across subjects. For example, all the ABR waveforms for all the Non-White Males were averaged point-by-point in time to create an averaged waveform that then could be compared with the averaged waveforms for other groups such as the Non-White Females or the White Males. These averaged waveforms were used solely as a visual summary of the results. Averaged waveforms are problematic as summaries of AEP data , 4310, 4s e.g., , 23)..within-sleft-most bars show the results pooled across the phases of the menstrual cycle, and the results partitioned by cycle also are shown inside those panels. In the male panels, the right-most bars show the results pooled across all male subjects , while the results for the Post-VMm and Pre-VMm males are shown separately to the left inside those panels. Because the malfunction of the VM was not relevant for the ABR and AMLR measures, the most reliable comparisons of the two sexes are the bars at the far left of our figures vs. the bars at the far right, and those are the comparisons used in the primary analyses below. Similar figures are shown for each of the other ABR measures in . When the subjects were partitioned by race (bottom panels), female latencies remained shorter than male latencies, but race and sex interacted. Namely, the mean latencies for males and females were more similar for the Non-White subjects  than for the White subjects . Interactions of this sort were present for the majority of the ABR measures.  Also evident in The results in first three rows of The effect sizes shown in p-values for implied significance (for simplicity we concentrate on the top three rows). The absence of a significant sex difference for latency of Wave I is a common finding e.g., [Columns 2–6 and 8 of ng e.g., . . HoweAlong with Wave-I latency, the amplitude ratio V/I was an unusual ABR measure in that it did not show a substantial sex difference. The V/I ratio has clinical interest because it can be informative about the site-of-lesion in the auditory chain .The large effect sizes for the interpeak interval I–> V (for both races) are in accord with , 43, neiAlso notable in within-sex, so they miss the interactions between race and sex that are revealed by examination of the figures. The effect of race is visually compelling in several of the figures made for the individual ABR measures , the discussion here focuses on the sex, race, and menstrual-cycle About half the AMLR latency and amplitude measures exhibited notable sex differences . SoPast findings suggest that both the latency and amplitude of AMLR peaks are more highly dependent upon the specifics of the stimulus than are ABR peaks , meaningWe consider the latency and amplitude measures for AMLR in separate sections.vs. the bars at the far right of the male panel. Also evident in latency measures in interactions between race and sex. The moderately large sex difference for Wave Pa for the White subjects is in accord with the report by [The effect sizes for sex, race, and menstrual cycle are shown for each of the 8 AMLR eport by . McFaddeeport by  reportedNon-White subjects than for the White subjects.The amplitude measures for AMLR showed fewer notable differences between the sexes than did the amplitude measures for ABR discussed above. That said, these data did exhibit a feature contrary to one seen for most of the ABR and AMLR latency measures discussed so far: for all 6 measures of AMLR amplitude, the effect sizes for sex difference were numerically larger for the The AMLR amplitude measure showing the largest sex difference and a modest interaction between sex and race (Pa-Nb amplitude with the 40-dB click) is shown in As noted above, averaged waveforms were calculated for each subject group as a way of illustrating the sex, race, and menstrual-cycle differences detailed in the figures and tables above. Although averaged waveforms have appeal as qualitative depictions of AEP data, they possess several weaknesses , for a particular AEP measure, there was a tendency for the sex difference to be larger for the weak click than for the stronger click.none of the 20,000 random resamples yielded an effect size larger than the value actually obtained. The next largest sex differences were for Wave-Po latency. For both click levels, those effect sizes were about -0.8, with implied significance of 0.0001 from resampling. The latency measures involving Waves Na or Pa yielded no sex difference that was large, medium, or significant. For amplitude measures, the largest sex difference was for the last wave measured, Pa-Nb with the 40-dB click. That effect size was -0.72  and the implied significance was 0.0006.The largest sex differences observed were for Wave-V latency. For both click levels, those effect sizes were about -1.2 ; also for both click levels, In accord with past findings , 5–7, 43Also in accord with past findings –5, the sFor readers interested in the physiological origins of sex differences in ABRs and AMLRs, note that  reportedwithin-sex  and the auditory behavior of these same subjects , 2. Now All the information we had about the race/ethnicity of our subjects came from the two questions required by the National Institutes of Health  proxy variable, we hope interest in race increases because finding auditory race differences is a step in the direction of finding those individual differences in biology and physiology that underlie the basic mechanisms of everyday hearing.Contrary to expectation, all of the comparisons between the Menses and Midluteal phases of the menstrual cycle exhibited small effect sizes and none achieved implied significance .–49.45–49Correlations were calculated to determine how the various AEP measures were related to each other, and how the various AEP measures were related to OAE and psychoacoustical measures obtained from the same subjects. Because sex differences existed for many of the AEP measures, all correlations were done within-sex, both pooled over race and partitioned by race. All possible intercorrelations were performed for the 8 ABR measures, for the 8 AMLR latency measures, and for the 6 AMLR amplitude measures. In addition, all the ABR measures were compared with all the AMLR measures, and all the ABR and AMLR measures were compared with 4 types of OAE. The outcomes were summarized in section III.D. These findings address goals 5 and 6 in section I.A.Many of the intercorrelations for ABRs and for AMLRs were large and significant. However, most of the correlations calculated between AEPs and OAEs were small and did not achieve implied significance; those that did achieve implied significance typically were not consistent across sex or race , whereaThe absence of even moderate correlations between Wave V and detection of the 3.0-kHz tone in the quiet was a minor surprise  region of the basilar membrane , where tsmall individual differences in auditory sensitivity  compared to larger individual differences in AEPs, thus producing weak correlations.One possibility is that our relatively stringent screening of subjects resulted in Weak correlations can result when there is high variability in the measurements; here we averaged over multiple AEP (and OAE) measurements for each female subject, and, for both sexes, the psychoacoustical means were based on many blocks of trials for each subject (see ). Thus, A long-standing question in the scientific discussion of sex differences is whether the distributions of female and male values have different shapes. Specifically, it long has been observed that the variability of the male distribution often is greater than that of the female distribution, meaning that more males exist at the extremes. A review can be found in . AlthougThe result was that the variances for males were larger than those for the females for 73% of the AEP measures. The mean sex ratio was about 1.2 for the ABR measures, and about 2.0 and 1.8 for the latency and amplitude measures for AMLR, respectively. Those were the results when the data were pooled over race and menstrual cycle for the females and pooled over race for the males, but the tallies were similar when the data were partitioned by race. Accordingly, the numerous interactions between sex and race reported here were not the result of systematic differences in variance for the two race groups. Generally similar percentages for the variance ratios were obtained when the four OAE and seven psychoacoustical measures were examined in the same way. Thus, we provide modest support for the "greater male variability hypothesis," using measures that are highly unlikely to be subject to social or cultural influences (see ).For completeness we note that the mean/variance ratios for the 22 AEP measures were invariably smaller than 1.0 for the amplitude data and typically larger than 10.0 for the latency data, with no obvious trends by sex or race.It is important to note that negative results are not equivalent to no results. Negative results can contribute to knowledge, if not the same way as positive results. For example, the absence of strong correlations between AEPs and our psychoacoustical tasks suggests that the electrical potentials we recorded from the scalp either are not precise enough to detect activity in the relevant neural channels, or were not evoked by an appropriate stimulus, or some other explanation. Our negative results suggest changes in the experimental procedure that future investigators might explore to find stronger correlations  and thereby possibly learn more about processing in the brain. As another example, the relative absence of large sex differences in latency for the later peaks in the AMLR Click here for additional data file.