Search Results (37)

Background: The use of tapered fluted revision stems has been shown to be reliable and safe. Primary stability is mandatory for a long-lasting fixation between bone and a prosthesis. Nevertheless, aseptic loosening due to insufficient primary stability occurs and may be related to technically improper preparation of the femoral canal. Instructions of manufacturers are heterogeneous regarding preparation of implant beds. Questions/Purposes: Does speed or the design of the reamer influence the accuracy of the implant bed and, consecutively, primary stability? Materials and Methods: A test foam with an elastic moduli and pressure resistance similar to that of cancellous bone was used. The medullary canal was prepared with the use of reamers of two different straight and tapered femoral revision devices. Three different rotational speeds were used for preparation. After preparation, primary stability was measured and fixating characteristics were derived. Results: Sufficient primary stability was achievable by all three preparation methods but fixating characteristics were different. Significantly higher micro-motions were detected near the tip of the prosthesis compared to those at all more proximal measuring points. Reaming with high velocity resulted in significantly higher micro-motions compared to that with mid- or low-speed burring. Conclusions: Different preparation methods may be one explanation for the range of reported survivorship data of the two devices with aseptic loosening as the end point. The precision of the implant bed and fixating characteristics were best after reaming with lower velocity. Superior but not significantly better fixation characteristics were achieved with the monobloc stem compared to those with the modular device. Full article

According to the latest Verizon DBIR report, credential abuse, including password reuse and human factors in password creation, remains the leading attack vector. It was revealed that most users change their passwords only when they forget them, and 35% of respondents find mandatory password rotation policies inconvenient. These findings highlight the importance of combining technical solutions with user-focused education to strengthen password security. In this research, the “human factor in the creation of usernames and passwords” is considered a vulnerability, as identifying the patterns or rules used by users in password generation can significantly reduce the number of possible combinations that attackers need to try in order to gain access to personal data. The proposed method based on an LSTM model operates at a character level, detecting recurrent structures and generating generalized masks that reflect the most common components in password creation. Open datasets of 31,000 compromised passwords from real-world leaks were used to train the model and it achieved over 90% test accuracy without signs of overfitting. A new method of evaluating the individual password creation habits of users and automatically fetching context-rich keywords from a user’s public web and social media footprint via a keyword-extraction algorithm is developed, and this approach is incorporated into a web application that allows clients to locally fine-tune an LSTM model locally, run it through ONNX, and carry out all inference on-device, ensuring complete data confidentiality and adherence to privacy regulations. Full article

This study investigates whether audit tenure mandates—designed to curb managerial discretion—may unintentionally enable disguised opinion shopping. Specifically, it examines whether firms benefit from observed mandates that align with their unobservable preferences, despite appearing to comply with mandatory audit firm rotation or retention rules. A counterfactual framework is developed to estimate firms’ preference for switching or retention in the absence of regulation, allowing identification of strategic alignment under constraint. Empirical analysis using Korean data from 2000 to 2009 reveals that firms classified as disguised opinion shoppers are more likely to receive unmodified audit opinions and exhibit lower audit quality, as indicated by higher discretionary accruals and more frequent reporting irregularities. These effects are concentrated under mandatory retention and not observed under rotation, suggesting that forced auditor turnover weakens firms’ ability to secure favorable outcomes. Additional evidence shows that these firms are more likely to retain the same auditor after mandates expire, consistent with a reward-for-accommodation mechanism. Thus, this study not only provides empirical evidence that opinion shopping can persist under auditor tenure mandates, but also introduces a novel method for identifying such behavior when traditional signals—such as voluntary dismissals—are unavailable. These findings inform ongoing regulatory debates on the effectiveness of tenure-based reforms. Full article

In industries dealing with motor drive systems, the use of real-time simulators for validating control codes is becoming increasingly mandatory. This is particularly essential for systems with advanced control codes or complex microcontroller unit (MCU) register configurations, as this validation process helps prevent accidents and shorten development time. This study presents a validation process using a real-time simulator for the beatless control of six-step operation. Six-step operation, when applied to high-speed drives, has a limitation on the number of samples per electrical rotation, which causes voltage errors. A representative of these voltage error phenomena is the beat phenomenon, resulting in torque ripple at the first harmonic and high current ripple. To mitigate this beat phenomenon, a synchronous PWM method is sometimes used. However, in practical industrial systems, it may not be feasible to synchronously adjust the inverter’s switching frequency with the rotation speed. This study proposes a beatless control method to eliminate the voltage errors caused by the beat phenomenon during six-step operation at a fixed switching frequency. The specific implementation of this control method is explained based on MCU timer register settings. While previous studies have only proposed beatless control methods, this paper goes further by implementing the proposed beatless method using the MCU (TMS320F28335) to generate gating signals and validating the implementation through simulation on a permanent magnet synchronous motor using a real-time simulator (Typhoon HIL). Full article

We examine the impact of regulated auditor tenure on the shopping for favorable audit reports. We predict that these regulations may affect auditors’ willingness to acquiesce and clients’ incentives to engage in opinion shopping. We draw from the unique Korean setting where both mandatory audit firm retention and mandatory rotation were implemented for all public firms in a staggered manner. Based on hand-collected audit reports, we identify harmful language in explanatory paragraphs. We define favorable audit reports as those with unqualified opinions and without any harmful explanatory language. We find that opinion shopping for favorable audit reports appears to subside after mandatory retention but increases after mandatory rotation, with the positive impact of mandatory retention offset by the negative impact of mandatory rotation. We add to the literature by examining the impact of regulated auditor tenure on opinion shopping and highlighting the potential unintended consequences of these regulatory attempts. Full article

Computer vision is a powerful tool in medical image analysis, supporting the early detection and classification of eye diseases. Diabetic retinopathy (DR), a severe eye disease secondary to diabetes, accompanies several early signs of eye-threatening conditions, such as microaneurysms (MAs), hemorrhages (HEMOs), and exudates (EXs), which have been widely studied and targeted as objects to be detected by computer vision models. In this work, we tested the performances of the state-of-the-art YOLOv8 and YOLOv9 architectures on DR fundus features segmentation without coding experience or a programming background. We took one hundred DR images from the public MESSIDOR database, manually labelled and prepared them for pixel segmentation, and tested the detection abilities of different model variants. We increased the diversity of the training sample by data augmentation, including tiling, flipping, and rotating the fundus images. The proposed approaches reached an acceptable mean average precision (mAP) in detecting DR lesions such as MA, HEMO, and EX, as well as a hallmark of the posterior pole of the eye, such as the optic disc. We compared our results with related works in the literature involving different neural networks. Our results are promising, but far from being ready for implementation into clinical practice. Accurate lesion detection is mandatory to ensure early and correct diagnoses. Future works will investigate lesion detection further, especially MA segmentation, with improved extraction techniques, image pre-processing, and standardized datasets. Full article

Most of the parts of furniture made of medium density fiberboards (MDF) require at least one hole to be assembled. The drilling technological parameters influence the quality of holes. Factors such as tip angle of the drill bit, feed rate, type and diameter of the drill bit, and spindle rotational speed could affect the drilling process. Therefore, the right choosing of drilling parameters is a mandatory condition to improve the drilling efficiency that is expressed through tool durability, cost, and quality of the drilling. Thus, in this work, we are proposed an approach that consists in combining two modelling techniques, which were successfully applied in various fields, namely artificial neural network (ANN) and response surface methodology (RSM), to analyze and optimize the drilling process of MDF boards. Four artificial neural network models with a reasonable accuracy were developed to predict the analyzed responses, namely delamination factor at inlet, delamination factor at outlet, thrust force, and drilling torque. These models were used to complete the experimental design that was requested by the RSM. The optimum values of the selected factors and their influence on the drilling process of the MDF boards were revealed. A part of optimum combinations among analyzed factors could be used both during the drilling of the MDF boards and prelaminated wood particleboards. Full article

Assessing scapular position and motion during functional arm movement patterns may add relevant information to the evaluation of the clinical status and athletic performance of overhead sports athletes’ shoulders. This study aimed to examine the three-dimensional scapular kinematics of elite volleyball players with (n = 11) and without scapular dyskinesis (n = 11) in comparison to non-athletes (n = 27). Four distinct arm elevation/depression tasks were assessed: shoulder abduction/adduction, flexion/extension, scaption, and a diagonal movement pattern mimicking throwing (proprioceptive neuromuscular facilitation diagonal 2 for flexion/extension or PNF–D2–flx/ext). Kinematic data was recorded from the spiking/dominant shoulder using an electromagnetic system (FASTRAK, Polhemus Inc., Colchester, VT, USA); MotionMonitor v9 software, Innovative Sports Training, Inc., Chicago, IL, USA). The study compared scapular rotations at 15° intervals of humero-thoracic (HT) angles, ranging from minimum to 120°. Significantly different 3D scapular kinematics were observed between traditional arm motion tasks and PNF–D2 arm motion task (HT angle × task interaction effect, p < 0.001, 0.275 ≤ ${\eta }_p^2$ ≤ 0.772). However, when considering the combined influence of phase, HT angle, task, and group factors, no differences were found between groups (phase × HT angle × task × group, p ≥ 0.161, 0.032 ≤ ${\eta }_p^2$ ≤ 0.058). The inclusion of a functional arm movement pattern when evaluating scapular position and movement in overhead athletes does not appear to be mandatory. However, these findings are preliminary and highlight the need for more research in this area. Full article

Teak (Tectona grandis) is a deciduous tree producing a popular, expensive, fancy timber with versatile utilization. The teak population and its habitats in the natural forest have been decreasing consistently; thus, the IUCN Red List classifies it as an endangered species. Teak tree logging from its native natural forest is banned, and commercial teak timber can only be harvested from the plantation. People plant teak on their private lands or in the community forest to meet the increasing demand. This study analyzed the annual tree rings of a teak disk taken from the community plantation and aimed to determine its biological rotation age. Tree ring interpretation provides the increment and growth that are mandatory fundamental components of knowledge in sustainable forest management. It may also decipher the tree’s biography, which contains information about past climate and future predictions responding to climate change. All of the disk’s annual tree rings were digitized, transformed, and then curve-fitted using an elliptical polar form of non-linear regression. The best-fitted curve estimation of every annual tree ring was employed to determine their age-related diameter and basal area, and then allometric equations estimated the above-ground biomass and clear-bole volume. The continuous and discrete formula fit the growth curve well, and this study determined that Chapman-Richards is the best fit among others. The growth curve, current annual increment (CAI), and mean annual increment (MAI) were graphed based on the clear-bole volume, above-ground biomass, and log timber price. The CAI and MAI intersections result in 28, 30, and 86 years of optimum harvesting periods when the growth calculation is based on volume, above-ground biomass, and log timber price, respectively. These results identified that the teak plantation is a sustainable and highly valuable asset to inherit with long-term positive benefits. The sociocultural provision of teak plants as an inheritance gift for the next generation has proven to be economically and ecologically beneficial. Full article

Surgical knots are sequences of half-knots (H) or half-hitches (S), defined by their number of throws, by an opposite or similar rotation compared with the previous one, and for half-hitches whether they are sliding (s) or blocking (b). Opposite rotation results in (more secure) symmetric (s) knots, similar rotation in asymmetric (a) knots, and changing the active and passive ends has the same effect as changing the rotation. Loop security is the force to keep tissue together after a first half-knot or sliding half-hitches. With polyfilament sutures, H2, H3, SSs, and SSsSsSs have a loop security of 10, 18, 28, and 48 Newton (N), respectively. With monofilament sutures, they are only 7, 16, 18, and 25 N. Since many knots can reorganize, the definition of knot security as the force at which the knot opens or the suture breaks should be replaced by the clinically more relevant percentage of clinically dangerous and insecure knots. Secure knots with polyfilament sutures require a minimum of four or five throws, but the risk of destabilization is high. With monofilament sutures, only two symmetric+4 asymmetric blocking half-hitches are secure. In conclusion, in gynecology and in open and laparoscopic surgery, half-hitch sequences are recommended because they are mandatory for monofilament sutures, adding flexibility for loop security with less risk of destabilization. Full article

The subject of Graphic Expression, which is mandatory in the first year of engineering studies, showed poor academic results in recent years. This study analyzes the relationship and predictive capacity of various variables that previous research highlighted as relevant: prior academic preparedness, educational itinerary followed, mental rotation skills, videogame usage, as well as the gender and age of the students. A total of 161 first-year engineering students from a technical university in southern Europe participated in the study. Their spatial rotation skills were evaluated using the MRT-A, gathering information about the rest of the relevant variables and obtaining their academic results at the end of the course. The predictive capacity of the variables on academic performance was determined through linear regression techniques (grade in the subject, on a 0–10 scale) and logistic regression (pass/fail). All variables are significantly related to academic results in the expected direction, except for videogame usage and gender. No significant differences in spatial skills were found between genders, although differences were observed in videogame usage. The best predictors of performance are prior preparation and the educational itinerary followed. The results are discussed considering previous research, highlighting measures to improve results in Graphic Expression, with emphasis on training in spatial skills. Full article

Machine failure in modern industry leads to lost production and reduced competitiveness. Maintenance costs represent between 15% and 60% of the manufacturing cost of the final product, and in heavy industry, these costs can be as high as 50% of the total production cost. Predictive maintenance is an efficient technique to avoid unexpected maintenance stops during production in industry. Vibration measurement is the main non-invasive method for locating and predicting faults in rotating machine components. This paper reviews the techniques and tools used to collect and analyze vibration data, as well as the methods used to interpret and diagnose faults in rotating machinery. The main steps of this technique are discussed, including data acquisition, data transmission, signal processing, and fault detection. Predictive maintenance through vibration analysis is a key strategy for cost reduction and a mandatory application in modern industry. Full article

Wear-resistant coatings improve the machining capability of cutting tools and extend their useful life. However, when a tool needs to be reused, it is mandatory to remove the existing coating to facilitate resharpening and recoating. The existing technique uses electrochemical stripping, which is hazardous to the environment. The environmentally friendly pulsed laser stripping causes the melting and mixing of tools and coating materials, which makes it difficult to separate and remove the coating. This paper presents the results of coating stripping via a beam of fast argon atoms. Due to the twentyfold compression of the beam, a 3 µm thick AlTiN coating was removed from a rotating solid carbide end mill within 25 min. A subsequent one-hour-long irradiation of the cleaned tool with the same beam led to a decrease in the radius of the tool’s cutting edges from 10.5 to 3.5 µm. This allowed us to redeposit a 3.5 µm thick AlTiN coating and obtain a coated end mill with a cutting-edge radius of 7 µm. Full article

After the long period of mandatory distance learning, either synchronous or asynchronous, caused by the COVID-19 pandemic, the existence of learning tools to support students in similar scenarios is welcomed in many curriculum subjects. Geometric transformations are relevant in mathematics and an omnipresent topic in the computer graphics curriculum that needs plenty of visual tools and learning-by-doing environments. In this work, we propose a framework based on an extended Translation-Rotation-Scale (TRS) pattern to generate composite transformations to support a specific style of learning exercises that we call “before and after”. The pattern, together with specific constraints to reduce the domain into a finite set of cases, allows the automatic exercises generation, evaluation, and real-time feedback. Two pieces of software, called GTVisualizer and GTCards, were developed to empirically test the proposed framework embedding it in a gaming environment. The first tool supports the initial instruction and introduces the formal matrix-based methodology to specify composite transformations; the second one provides a ludic environment where students can drill and reinforce the subject by playing. Our initial results suggest that these tools are suitable for learning geometric transformations; they helped students in simulated self-study mode achieve comparable results to those students receiving the regular lecture materials and explanations in the classroom. Moreover, the usage of the tools appears to favor a similar increasing effect on students’ visual-spatial abilities, similar to the obtained by taking an in-person course on computer graphics, as measured with the Purdue Spatial Visualization Test. Full article

The present study aims to investigate the effects of mandatory requirements of audit firm rotation on earnings management among companies listed on the Tehran Stock Exchange (TSE). The study population consists of 1030 observations and 103 companies listed on the TSE during the years 2003–2012; moreover, the statistical technique used to test the hypotheses is panel data and pooled data. The results showed that the rule of mandatory audit firm rotation increased accruals-based earnings management (AEM) significantly. In addition, outcomes demonstrated that mandatory requirements of audit firm rotation did not have a significant influence on real earnings management (REM) and audit fees. Overall, our findings proved that the mandatory requirements of audit firm rotation in Iran have not been able to prevent the opportunistic actions of management at a time when they were faced with severe financial problems because of economic sanctions and auditors taking standardized systems-based auditing approaches. This research will make investors and others aware of the fact that mandatory audit firm rotation might be not effective in stopping managers wishing to manipulate the accounting figures. This paper actually suggests that when firms have financial distress, regulatory mechanisms such as audit firm rotation may not have a deterrent role. Our findings give lawgivers a stark warning that the length of an audit firm’s tenure should be based on the features of the audit market structure of each country. Full article