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This paper describes the orthodontic treatment of two cases that were successful in winning the William Houston Gold Medal at the Membership in Orthodontics Examinations of the Royal College of Surgeons of Edinburgh in 2022. Both cases discuss the management of palatally impacted maxillary canines and treatment was initiated during the emerging COVID-19 crisis and completed over a 27-month period. The first case describes the management of a 15-year-old female with a Class II division 1 incisor relationship complicated by a palatally impacted upper left canine, moderate upper and lower arch crowding, and a lower centreline discrepancy with an associated right lateral displacement on closure. Treatment involved open surgical exposure of the impacted canine, a quad helix appliance, premolar extractions, and upper and lower fixed appliances. The second case describes the management of a 14-year-old female with a Class III incisor relationship complicated by bilaterally impacted maxillary canines, impeded eruption of the lower right second molar, moderate lower and severe upper arch crowding, and an upper centreline discrepancy. These case reports aim to demonstrate the high standards of care achieved by Orthodontic Specialty Trainee Registrars in the UK and provide aspirational standards for future trainees. [ABSTRACT FROM AUTHOR]

This research manuscript describes the process of degradation of an Armox 600 armour plate during the impact of a 5.56x45 mm SS109 projectile. The creation process of the numerical FEM model of the projectile is presented. The projectile impact angle is set between 15° and 90°, and this phenomenon is investigated via numerical and experimental approaches. The experiment is conducted under the same conditions as the numerical approach to validate the FEM model. The experiments are conducted using a high-speed camera. This research manuscript presents the influence of the projectile impact angle on the degradation of the armour plate and its protection capability for different angles. The results demonstrate the dependence of the transferred energy on the armour plate, speed of the particles after impact, and trace dimensions on the armour plate for different impact angles. [ABSTRACT FROM AUTHOR]

The shoulder joint complex in the overhead athlete is organized to effectively transfer the proximally generated forces distally into the arm. The organization also protects the joints and anatomic structures against the repetitive high velocities, large ranges of motions, and compressive, shear, translational, and distraction loads in the overhead motion while placing the hand in the "launch window." Coupling of the movements of the scapula, clavicle, and humerus results in scapulohumeral rhythm (SHR). Effective SHR requires the clavicle and scapula—and, at times, the mechanically linked claviscapular segment—to move the arm into the task-specific position and motion and requires the humerus to move through the ranges of motion to achieve the specific task in the throwing motion. Alterations in SHR can negatively affect effective shoulder joint complex function in the overhead throwing motion and increase injury risk. There are 4 phases of clavicular, scapular, and claviscapular motion that are coupled with arm motion in SHR. The first 3 phases occur in arm elevation motions from 0°-90° and result in the claviscapula and humerus being placed in task-specific positions. The fourth phase is coupling of claviscapular motion with humeral motion to maintain ball-and-socket kinematics throughout the throwing motion. Alterations in this composite motion are termed "scapular dyskinesis." The dyskinesis is considered an impairment of the efficient mobility of the claviscapular segment of the shoulder complex. The most prevalent problem with scapular dyskinesis is the association of scapular protraction and consequent glenoid antetilt with alterations in humeral rotation and posterior humeral head translation to produce shoulder joint internal impingement. Task effectiveness in overhead throwing is also based on and determined by humeral range of motion, precision of humeral motion, and velocity of humeral motion, as well as humeral and arm position in 3-dimensional space. This activity requires maximum ball-and-socket kinematics to create the highest amount of concavity-compression that creates stability for the joint. There are bony and soft-tissue contributions to this stability. Injuries to the glenoid labrum are among the most common deficits that alter concavity-compression. Clinical evaluation of the shoulder joint complex in the injured throwing athlete should be comprehensive and systematic, following an evaluation pathway for proximal and distal causative factors and including observation of humeral motion. This type of evaluation can result in intervention protocols that address the pathoanatomic, pathophysiological, and pathomechanical deficits identified. [ABSTRACT FROM AUTHOR]

This review research assesses the numerous 3D printing methods utilized in medical applications and the materials and design methods that are associated with the current and existing technology. The article thoroughly examines the advantages and disadvantages of various techniques and materials and the difficulties of applying 3D printing technology to the medical sector. Further research and development are required to overcome current challenges since the review highlights the importance of design strategies in achieving positive medical outcomes. Overall, the article provides a thorough overview of the state of 3D printing in medical applications today and its potential to revolutionize the industry. [ABSTRACT FROM AUTHOR]

Regenerative biomaterials for musculoskeletal defects must address multi-scale mechanical challenges. Repairing craniomaxillofacial bone defects, which are often large and irregularly shaped, requires close conformal contact between implant and defect margins to aid healing. While mineralized collagen scaffolds can promote mesenchymal stem cell osteogenic differentiation in vitro and bone formation in vivo, their mechanical performance is insufficient for surgical translation. We report a generative design approach to create scaffold-mesh composites by embedding a macro-scale polymeric Voronoi mesh into the mineralized collagen scaffold. The mechanics of architected foam reinforced composites are defined by a rigorous predictive moduli equation. We show biphasic composites localize strain during loading. Further, planar and 3D mesh-scaffold composites can be rapidly shaped to aid conformal fitting. Voronoi-based composites overcome traditional porosity-mechanics relationship limits while enabling rapid shaping of regenerative implants to conformally fit complex defects unique for individual patients. Biomaterial strategies for (craniomaxillofacial) bone regeneration are often limited by the size and complex geometry of the defects. Voronoi structures are open-cell foams with tunable mechanical properties which have primarily been used computationally. We describe generative design strategies to create Voronoi foams via 3D-printing then embed them into an osteogenic mineralized collagen scaffold to form a multi-scale composite biomaterial. Voronoi structures have predictable and tailorable moduli, permit stain localization to defined regions of the composite, and permit conformal fitting to effect margins to aid surgical practicality and improve host-biomaterial interactions. Multi-scale composites based on Voronoi foams represent an adaptable design approach to address significant challenges to large-scale bone repair. [Display omitted] [ABSTRACT FROM AUTHOR]

Serious damage to near-fault structures is caused mainly by velocity pulses in a ground motion, hence, the necessity to develop a pulse-related definition of strong-motion duration to adequately describe the intensity of near-fault ground motion. For a multipulse record, an ideal-pulse-based strong-motion duration, which is defined as the time interval between the beginning of the first pulse and the end of the last pulse in an ideal-pulse signal, is proposed. This strong-motion duration corresponds with the time interval of the occurrence of strong vibrations and energy accumulations in the original record. For near-fault records, pulselike characteristics can be completely presented within this duration. Meanwhile, the ideal-pulse-based strong-motion duration shows good performance in the estimation of structural responses. The elastic and inelastic displacement spectra of the original records agree well with those of the records shortened according to the proposed duration. The validity of applying the proposed duration to structural analysis is further verified by the nonlinear time history analyses of 3-, 9-, and 20-story steel moment-resisting frame structures. The proposed strong-motion duration accurately estimates nonlinear structural responses. It is proven that the ideal-pulse-based strong-motion duration can adequately describe the intensity of near-fault ground motions, both from the perspective of the energy accumulation process in a ground-motion record and that of the structural analyses subjected to these ground motions. [ABSTRACT FROM AUTHOR]

A male patient aged 11 years presented a large dentigerous cyst in the lower left quadrant associated with retained deciduous lower lateral incisor and canine and impacted, unerupted corresponding permanent ones. The treatment consisted in marsupialisation and placement of a modified lingual arch that held a tube for decompression used for irrigation of the cystic cavity in a comfortable way for the patient and for the clinician. The same lingual arch was later used as an anchorage method for traction of the retained teeth. The final records showed complete resolution of the cyst and retained teeth were successfully Aligned into the oral cavity. [ABSTRACT FROM AUTHOR]

The maxillary permanent central incisor (MPCI) has been reported to be rotated in up to 96% of cleft patients. A severely rotated MPCI is highly visible when smiling, drawing attention to a repaired cleft lip, and is often the main presenting complaint of a patient with cleft lip and palate attending for orthodontic treatment. The benefit of interceptive orthodontic treatment to alleviate these concerns must be weighed up against the consequences of adding to the already substantial orthodontic burden likely to be faced by these patients. Despite the high prevalence of this dental abnormality among cleft patients, there is little published in the literature regarding this type of malocclusion. This paper explores the aetiology, presentation and management of this condition, using examples from cases treated within our department. In addition, the commonly found pre-existing anomaly of a short root length is discussed, in combination with the implications this may have upon orthodontic treatment planning for a rotated MPCI. [ABSTRACT FROM AUTHOR]

Single Point Incremental Forming (SPIF) is an emerging materials processing technology. Owing to a number of merits, like reduced tooling, cycle time and cost and ability to produce sculptured profiles, in comparison to the traditional methods, the recent past has witnessed a growing interest in the application of SPIF to composite materials. This article authoritatively reviews the advancements in this area made since 2008. The review covers several aspects of the process including deformation characteristics, forming limits, failure modes forming forces, strain recovery, surface quality and analytical models. The current state of the technology and challenges are revealed, and many valuable findings are identified thereby setting guidelines for the process users. [ABSTRACT FROM AUTHOR]

Collagen fibrils are the fundamental structural elements in vertebrate animals and compose a structural framework that provides mechanical support to load-bearing tissues. Understanding how these fibrils initially form and mechanically function has been the focus of a myriad of detailed investigations over the last few decades. From these studies a great amount of knowledge has been acquired as well as a number of new questions to consider. In this review, we examine the current state of our knowledge of the mechanical properties of extant fibrils. We emphasize on the mechanical response and related deformation of collagen fibrils upon tension, which is the predominant load imposed in most collagen-rich tissues. We also illuminate the gaps in knowledge originating from the intriguing results that the field is still trying to interpret. Collagen is the result of millions of years of biological evolution and is a unique family of proteins, the majority of which provide mechanical support to biological tissues. Cells produce collagen molecules that self-assemble into larger structures, known as collagen fibrils. As simple as they appear under an optical microscope, collagen fibrils display a complex ultrastructural architecture tuned to the external forces that are imposed upon them. Even more complex is the way collagen fibrils deform under loading, and the nature of the mechanisms that drive their formation in the first place. Here, we present a cogent synthesis of the state-of-knowledge of collagen fibril mechanics. We focus on the information we have from in vitro experiments on individual, isolated from tissues, collagen fibrils and the knowledge available from in silico tests. [Display omitted] [ABSTRACT FROM AUTHOR]

Mechanics, also called applied mathematics is the branch of mathematics and physics that describes and explains how objects, energy, and forces interact with each other. The aim of this article is to provide the reader with definitions of these terms, and understanding of how they affect the physical world with clinical examples. [ABSTRACT FROM AUTHOR]

The article focuses on the principles of mechanics in physics, particularly work, energy, and power, and their relevance to physiology, such as in respiration and cardiac output. Topics include the definitions and equations for work, energy, and power, as well as their clinical applications in understanding the mechanics of breathing and myocardial contraction.

Copyright of Caderno Brasileiro de Ensino de Física is the property of Caderno Brasileiro de Ensino de Fisica and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The aim of this systematic review was to critically review and synthesise the findings from primary studies on pitching mechanics and performance of healthy adult baseball pitchers. Systematic review with meta-analysis. Eight English- and Japanese-language databases were systematically searched from inception to 22nd July 2022. In total, 29 descriptive biomechanical studies were included. Overall study quality was moderate. In subgroup analyses, professional pitchers showed significantly higher stride length, peak shoulder internal rotation velocity, peak shoulder proximal force and ball velocity compared to collegiate pitchers. Conversely, collegiate pitchers were found to have significantly higher peak pelvis rotation velocity. Available normative data suggested potentially heterogeneous pitching mechanics and performance between professional and collegiate pitchers. However, the findings in this review should be interpreted cautiously. Since statistical heterogeneity was significant within most data sets, more detailed subgroup analyses are required. Additionally, more high-quality studies utilising measurement systems with established reliability are required to obtain accurate data in baseball pitching mechanics and performance. [ABSTRACT FROM AUTHOR]

Aim: Bimaxillary protrusion is a common condition observed irrespective of race and ethnicity and is a chief concern for patients who seek orthodontic treatment. The aim of this study was to compare and evaluate changes in soft tissue structures and incisor positions in class I bimaxillary protrusion subjects undergoing orthodontic therapy when friction and frictionless mechanics were used. Methods: Two groups with a total of 40 patients aged 18-30 years diagnosed with class I bimaxillary protrusion treated by extracting first premolars were considered for this study. Patients treated with friction mechanics were included in Group 1 and those treated with frictionless mechanics in Group 2. The digital lateral cephalograms were calibrated and analyzed using Nemoceph software. Selected landmarks were marked on pre- and post-treatment cephalograms and assessed for intra- and inter-group soft tissue and incisor position changes. Student's t-test was used to analyze the collected data using SPSS 20 software. Result: Intragroup comparison revealed significant changes in both groups. Inter-group comparison of the selected parameters between groups 1 and 2 showed differences but without any statistical significance, except for the inter-incisal angle. Conclusion: Pre- and post-treatment comparison analysis revealed significant soft tissue changes in both groups. However, the comparison between friction and frictionless mechanics showed no statistically significant changes. [ABSTRACT FROM AUTHOR]

Synthetic hydrogels are attractive platforms due in part to their highly tunable mechanics, which impact cell behavior and secretory profile. These mechanics are often controlled by altering the number of crosslinks or the total polymer concentration in the gel, leading to structure-property relationships that inherently couple network connectivity to the overall modulus. In contrast, the native extracellular matrix (ECM) contains structured biopolymers that enable stiff gels even at low polymer content, facilitating 3D cell culture and permeability of soluble factors. To mimic the hierarchical order of natural ECM, this work describes a synthetic hydrogel system in which mechanics are tuned using the structure of sequence-defined peptoid crosslinkers, while fixing network connectivity. Peptoid crosslinkers with different secondary structures are investigated: 1) a helical, molecularly stiff peptoid, 2) a non-helical, less stiff peptoid, and 3) an unstructured, relatively flexible peptoid. Bulk hydrogel storage modulus increases when crosslinkers of higher chain stiffness are used. In-vitro studies assess the viability, proliferation, cell morphology, and immunomodulatory activity of human mesenchymal stem cells (hMSCs) on each hydrogel substrate. Matrix mechanics regulate the morphology of hMSCs on the developed substrates, and all of the hydrogels studied upregulate IDO production over culture on TCP. Softer substrates further this upregulation to a plateau. Overall, this system offers a biomimetic strategy for decoupling hydrogel storage modulus from network connectivity, enabling systematic study of biomaterial properties on hMSC behavior and enhancement of cellular functionality for therapeutic applications. Various strategies to tune hydrogel mechanics have been developed to control human mesenchymal stem cell (hMSC) behavior and regulate their immunomodulatory potential. However, these strategies typically couple mechanics to network connectivity, which in turn changes other hydrogel properties such as permeability that may have unintended effects on hMSC behavior. This work presents a strategy to tune hydrogel mechanics using crosslinkers with different secondary structure and molecular rigidity. This strategy successfully decouples hydrogel moduli from crosslinker stoichiometry and mimics the hierarchical nature of the native extracellular matrix. The moduli of the developed hydrogels led to significant impacts on hMSC morphology and proliferation, and increased immunomodulatory potential, indicating that molecular rigidity is a promising avenue to control engineered ECM mechanics for therapeutic applications. [Display omitted] [ABSTRACT FROM AUTHOR]

Collagen molecules are the base structural unit of tendons, which become denatured during mechanical overload. We recently demonstrated that during tendon stretch, collagen denaturation occurs at the yield point of the stress-strain curve in both positional and energy-storing tendons. We were interested in investigating how this load is transferred throughout the collagen hierarchy, and sought to determine the onset of collagen denaturation when collagen fibrils are stretched. Fibrils are one level above the collagen molecule in the collagen hierarchy, allowing more direct probing of the effect of strain on collagen molecules. We isolated collagen fibrils from both positional and energy-storing tendon types and stretched them using a microelectromechanical system device to various levels of strain. We stained the fibrils with fluorescently labeled collagen hybridizing peptides that specifically bind to denatured collagen, and examined whether samples stretched beyond the yield point of the stress-strain curve exhibited increased amounts of denatured collagen. We found that collagen denaturation in collagen fibrils from both tendon types occurs at the yield point. Greater amounts of denatured collagen were found in post-yield positional fibrils than in energy-storing fibrils. This is despite a greater yield strain and yield stress in fibrils from energy-storing tendons compared to positional tendons. Interestingly, the peak modulus of collagen fibrils from both tendon types was the same. These results are likely explained by the greater crosslink density found in energy-storing tendons compared to positional tendons. The insights gained from this study could help management of tendon and other musculoskeletal injuries by targeting collagen molecular damage at the fibril level. When tendons are stretched or torn, this can lead to collagen denaturation (damage). Depending on their biomechanical function, tendons are considered positional or energy-storing with different crosslink profiles. By stretching collagen fibrils instead of fascicles from both tendon types, we can more directly examine the effect of tensile stretch on the collagen molecule in tendons. We found that regardless of tendon type, collagen denaturation in fibrils occurs when they are stretched beyond the yield point of the stress-strain curve. This provides insight into how load affects different tendon sub-structures during tendon injuries and failure, which will help clinicians and researchers understand mechanisms of injuries and potentially target collagen molecular damage as a treatment strategy, leading to improved clinical outcomes following injury. [Display omitted] [ABSTRACT FROM AUTHOR]

To evaluate the effect of friction vs frictionless mechanics on the rate of anterior segment retraction (ASR) in patients with bimaxillary protrusion. Thirty females (18.3 ± 3.7 years) with bimaxillary protrusion were randomly allocated into the friction group, using elastomeric power chains, and the frictionless group, using T-loop springs for ASR. Eligibility criteria included absence of skeletal discrepancies and any systemic diseases or medications, among others. Randomization in a 1:1 ratio was generated by Microsoft Excel. Opaque sealed envelopes were sequentially numbered for allocation concealment. Only blinding of the outcome assessor was applicable. Activations were done every 4 weeks until completion of ASR. The primary outcome was the rate of ASR measured on digital models. Anchorage loss, molar rotation, and pain experienced were also assessed. Two patients were lost to follow-up. The rate of ASR was 0.68 ± 0.18 mm/mo in the friction group vs 0.88 ± 0.27 mm/mo in the frictionless group, with no significant difference. A significant difference in anchorage loss of 1.63 mm and molar rotation of 7.06° was observed, being higher in the frictionless group. A comparable pain experience associated with both mechanics was reported. No difference in the rate of ASR or pain experience was observed between friction and frictionless mechanics. However, extra anchorage measures should be considered when using frictionless mechanics as greater anchorage loss and molar rotations are anticipated. [ABSTRACT FROM AUTHOR]

Scarring is a major clinical issue that affects a considerable number of patients. The associated problems go beyond the loss of skin functionality, as scars bring aesthetic, psychological, and social difficulties. Therefore, new strategies are required to improve the process of healing and minimize scar formation. Research has highlighted the important role of mechanical forces in the process of skin tissue repair and scar formation, in addition to the chemical signalling. A more complete understanding of how engineered biomaterials can modulate these mechanical stimuli and modify the mechanotransduction signals in the wound microenvironment is expected to enable scar tissue reduction. The present review aims to provide an overview of our current understanding of skin biomechanics and mechanobiology underlying wound healing and scar formation, with an emphasis on the development of novel mechanomodulatory wound dressings with the capacity to offload mechanical tension in the wound environment. Furthermore, a broad overview of current challenges and future perspectives of promising mechanomodulatory biomaterials for this application are provided. Scarring still is one of the biggest challenges in cutaneous wound healing. Beyond the loss of skin functionality, pathological scars, like keloids and hypertrophic, are associated to aesthetic, psychological, and social distress. Nonetheless, the understanding of the pathophysiology behind the formation of those scars remains elusive, which has in fact hindered the development of effective therapeutics. Therefore, in this review we provide an overview of our current understanding of skin biomechanics and mechanobiology underlying wound healing and scar formation, with an emphasis on the development of novel mechanomodulatory wound dressings with the capacity to offload mechanical tension in the wound environment. [Display omitted] [ABSTRACT FROM AUTHOR]

In creating constructivist inquiry-based active classrooms, the teacher has to resort to new teaching methods. To make mechanics concepts more meaningful and visible, we propose using an open-source software—Tracker—which can be easily downloaded. Fundamental concepts of mechanics can be easily taught by visualizing and analyzing the motion of the objects in the Tracker software environment. This article discusses some mechanical problems and how they can be visualized and solved using Tracker software. This software can benefit high school students to college students in analyzing different motions. This method is also known as the video-based analysis (VBA) method. This method can widely be used across different problems of mechanics and can be helpful in the effective teaching-learning process. In this article, we discuss how Tracker software can be used to solve some real-life mechanics problems. [ABSTRACT FROM AUTHOR]

To obtain opinions from orthodontic colleagues nationally on how they currently manage orthodontic patients with oral piercings. The secondary objectives were to assimilate the national opinions from the survey and attempt to generate educational material as an advice sheet and a patient information leaflet for the professionals and the patients respectively for the British Orthodontic Society (BOS). Cross-sectional survey. Primary and secondary care orthodontic providers. Members of the BOS. An electronic questionnaire was developed and circulated to members of the BOS to obtain their opinions on the effects of oral piercings on their patients' orthodontic treatment 'journey'. In addition, the need for the development of informative material around the management of orthodontic treatment and appliances in patients with oral piercings was explored. A total of 110 responses were received. However, only 88 respondents out of 110 attempted all the questions within the survey. There were 22 respondents who attempted it partially. We did include these partial responses well while analysing the results, since many of these offered personalised comments in the free-text boxes within the survey. The most common general complications associated with oral piercings were inflammation of the surrounding tissue and enamel/dentine wear. Moreover, orthodontic complications, reported commonly, were inadequate oral hygiene maintenance, entanglement with the orthodontic appliance causing damage and interference with retainers. Most respondents expressed the need for the development of a web-based patient information leaflet and an advice sheet as educational tool, both of which have been proposed to and agreed by the BOS before submission of this publication. [ABSTRACT FROM AUTHOR]

In conventional Class II treatment, distalisation of the maxillary arch usually requires multiple phases of tooth movement during which anchorage loss can occur. In order to solve this issue, a rational and simple technique has been developed. Instead of using intraoral distalisers along with palatal mini-implants, Ni-Ti superelastic loops are used to obtain molar distalisation while buccal interradicular miniscrews (BIM), preferably placed between the roots of upper premolars, supply the necessary anchorage. Once the distalisation of molars and second premolars is performed, miniscrews are placed between the roots of first molars and second premolars after removing the previous miniscrews. Elastic chains or tie-backs, which go from the new miniscrews to the hooks of a 0.019×0.025-inch stainless-steel archwire, produce the retraction of incisors, canines and first premolars with optimal control of anchorage. Clinical cases are shown to illustrate the technique. [ABSTRACT FROM AUTHOR]

• Irrespective of shoe bending stiffness, prolonged running resulted in a redistribution of positive lower limb joint work from distal to proximal joints. • In the control shoe, positive ankle and knee joint work were significantly different from baseline for the first time at 5.0 and 5.5 km, respectively. In the stiff condition, positive ankle and knee joint work were significantly different at 8.0 and 7.5 km, respectively. • A delayed onset of work redistribution when running in stiff footwear could be beneficial as mechanical work is performed for an extended duration by distal muscle–tendon units with smaller muscle volume and longer tendons. This study aimed to investigate if changing the midsole bending stiffness of athletic footwear can affect the onset of lower limb joint work redistribution during a prolonged run. Fifteen trained male runners (10-km time of <44 min) performed 10-km runs at 90% of their individual speed at lactate threshold (i.e., when change in lactate exceeded 1 mmol/L during an incremental running test) in a control and stiff shoe condition on 2 occasions. Lower limb joint kinematics and kinetics were measured using a motion capture system and a force-instrumented treadmill. Data were acquired every 500 m. Prolonged running resulted in a redistribution of positive joint work from distal to proximal joints in both shoe conditions. Compared to the beginning of the run, less positive work was performed at the ankle (approximately 9%; p ≤ 0.001) and more positive work was performed at the knee joint (approximately 17%; p ≤ 0.001) at the end of the run. When running in the stiff shoe condition, the onset of joint work redistribution at the ankle and knee joints occurred at a later point during the run. A delayed onset of joint work redistribution in the stiff condition may result in less activated muscle volume, because ankle plantar flexor muscles have shorter muscles fascicles and smaller cross-sectional areas compared to knee extensor muscles. Less active muscle volume could be related to previously reported decreases in metabolic cost when running in stiff footwear. These results contribute to the notion that footwear with increased stiffness likely results in reductions in metabolic cost by delaying joint work redistribution from distal to proximal joints. [Display omitted] [ABSTRACT FROM AUTHOR]

Estimation of kinematic and dynamic parameters of weapon mechanisms during operation is one of the crucial elements of design and optimisation. This study presents results of numerical and experimental investigations of a short-recoil-operated weapon action cycle. Theoretical considerations were based on multibody systems and finite element approaches. An experimental stand was adopted to investigate the kinematic characteristics of pistol parts and provide a set of slide displacement and velocity time courses. Comparison of theoretical and experimental data allowed for positive validation of the investigated model. The multibody systems numerical approach ensured a maximum relative discrepancy with experiment of 3.5 per cent for the velocity of recoiled parts, while finite element analysis calculations yielded a value of 12.7 per cent. Finally, parametric analyses were conducted to determine the influence of selected design characteristics on weapon operation. The analyses proved the correctness of the adopted design assumptions. [ABSTRACT FROM AUTHOR]

Global longitudinal strain (GLS) is becoming routinely used to direct the medical management of various cardiac diseases, but its application in pregnancy is unclear. Our objective was to perform a meta-analysis and pool multiple study data to consolidate the evidence base for the role of GLS in the assessment of women with hypertensive disorders of pregnancy (HDP). Electronic database searches were performed in PubMed/Medline and EMBASE for research articles reporting GLS in pregnancies complicated by HDP and normotensive pregnancies that have been published up to September 2021. The meta-analysis included 17 studies with a pooled sample size of 1723 participants, which included 951 women with HDP, of which 680 were preeclamptic, and 772 controls. The primary random-effects pooled analysis demonstrated a statistically significant weighted mean difference in GLS between the HDP and control group (mean difference: 3.08% [CI, 2.33-3.82], P<0.001). When analyzed including only preeclamptic studies, there was also a statistically significant mean difference (mean difference: 2.98% [95% CI, 1.97-3.99], P<0.001). This meta-analysis demonstrates that HDP is associated with greater cardiac maladaptation, evidenced by a significantly reduced GLS compared with normal pregnancy. Echocardiography should be considered as a screening tool in women with HDP to enable early cardiovascular risk prevention through national initiatives. [ABSTRACT FROM AUTHOR]

This paper determines the chip formation mechanism, fiber-matrix failure modes, and cutting forces in orthogonal cutting of multi-directional carbon fiber reinforced polymer (MD CFRP) with interlaminar bonding effect. The cutting experiments show that the varying chip formation angles with different fiber orientations in cutting unidirectional plies converge for MD CFRP. A new analytical mechanics model for cutting MD CFRP is developed to predict the chip formation angle and failure modes based on the minimum energy principle for all plies. The model with experimental validation reveals the different cutting mechanisms between UD and MD CFRPs. [ABSTRACT FROM AUTHOR]

Tendinopathy is a debilitating disease that causes as much as 30% of all musculoskeletal consultations. Existing treatments for tendinopathy have variable efficacy, possibly due to incomplete characterization of the underlying pathophysiology. Mechanical load can have both beneficial and detrimental effects on tendon, as the overall tendon response depends on the degree, frequency, timing, and magnitude of the load. The clinical continuum model of tendinopathy offers insight into the late stages of tendinopathy, but it does not capture the subclinical tendinopathic changes that begin before pain or loss of function. Small animal models that use high tendon loading to mimic human tendinopathy may be able to fill this knowledge gap. The goal of this review is to summarize the insights from in-vivo animal studies of mechanically-induced tendinopathy and higher loading regimens into the mechanical, microstructural, and biological features that help characterize the continuum between normal tendon and tendinopathy. This review summarizes the insights gained from in-vivo animal studies of mechanically-induced tendinopathy by evaluating the effect high loading regimens have on the mechanical, structural, and biological features of tendinopathy. A better understanding of the interplay between these realms could lead to improved patient management, especially in the presence of painful tendon. [Display omitted] [ABSTRACT FROM AUTHOR]

Intractable human diseases such as cancers, are context dependent, unique to both the individual patient and to the specific tumor microenvironment. However, conventional cancer treatments are often nonspecific, targeting global similarities rather than unique drivers. This limits treatment efficacy across heterogeneous patient populations and even at different tumor locations within the same patient. Ultimately, this poor efficacy can lead to adverse clinical outcomes and the development of treatment-resistant relapse. To prevent this and improve outcomes, it is necessary to be selective when choosing a patient's optimal adjuvant treatment. In this review, we posit the use of personalized, tumor-specific models (TSM) as tools to achieve this remarkable feat. First, using ovarian cancer as a model disease, we outline the heterogeneity and complexity of both the cellular and extracellular components in the tumor microenvironment. Then we examine the advantages and disadvantages of contemporary cancer models and the rationale for personalized TSM. We discuss how to generate precision 3D models through careful and detailed analysis of patient biopsies. Finally, we provide clinically relevant applications of these versatile personalized cancer models to highlight their potential impact. These models are ideal for a myriad of fundamental cancer biology and translational studies. Importantly, these approaches can be extended to other carcinomas, facilitating the discovery of new therapeutics that more effectively target the unique aspects of each individual patient's TME. In this article, we have presented the case for the application of biomaterials in developing personalized models of complex diseases such as cancers. TSM could bring about breakthroughs in the promise of precision medicine. The critical components of the diverse tumor microenvironments, that lead to treatment failures, include cellular- and extracellular matrix- heterogeneity, and biophysical signals to the cells. Therefore, we have described these dynamic components of the tumor microenvironments, and have highlighted how contemporary biomaterials can be utilized to create personalized in vitro models of cancers. We have also described the application of the TSM to predict the dynamic patterns of disease progression, and predict effective therapies that can produce durable responses, limit relapses, and treat any minimal residual disease. [Display omitted] [ABSTRACT FROM AUTHOR]

Copyright of Estudios Filosóficos is the property of Estudios Filosoficos and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this section of Resonance, we invite readers to pose questions likely to be raised in a classroom situation. We may suggest strategies for dealing with them, or invite responses, or both. "Classroom" is equally a forum for raising broader issues and sharing personal experiences and viewpoints on matters related to teaching and learning science. [ABSTRACT FROM AUTHOR]

The underwater environmental monitoring system applying IoT is now developing for 4.0 industry. It helps not only to simplify work but also to increase efficiency and reduce costs and execution time as well as ensure health to avoid contact with toxic solutions. In this paper, we first model the process of measuring NH3 concentration manually to automate. Secondly, the proposed model is combined with the process of processing output image automatically and displaying the results on the server. Thirdly, the system is able to measure the concentration by VNC viewer connecting with Raspberry pi4 via WiFi. The result of the NH3 concentration parameter is sent to users quickly to alert promptly when it reaches a dangerous threshold. Experiments show that the system not only ensures fast processing time (less than 5 minutes) but also improves accuracy (up to 80%) comparing with real devices. [ABSTRACT FROM AUTHOR]

To determine if stretch shortening cycle potentiation of the lower extremity joints, specifically at the propulsion onset, is related to countermovement (CMJ) jump height (JHt) and enhancement of JHt in older vs young adults. Cross-Sectional Study. University Laboratory. Community-dwelling older adults and young adults (n=22, Older/young adults= 10/12. None. All the following outcome measures were collected for CMJ and static jump (SJ). JHt was calculated directly from the greater trochanter marker data as the highest value achieved during jump - standing upright height. Propulsion onset was calculated as the first positive data point (after the eccentric phase) of the joint angular velocity for each respective joint (hip, knee, and ankle). Joint extensor moments at the propulsion onset were calculated as the percentage of the peak extensor moment for each respective joint for each jump condition (CMJ and SJ). All the joint extensor moments were normalized for body weight. Ratios of (1) JHt (JH) and (2) respective joint-specific extensor moments for CMJ/SJ were calculated as surrogate markers of potentiation at the propulsion onset. All participants demonstrated JHt potentiation (p< 0.05) with 14% lower JHt potentiation in older adults (p< 0.05). All participants demonstrated extensor moment potentiation at all joints (p< 0.001 for both). Further, extensor moment potentiation of the ankle was greater than knee and hip (p< 0.01 for both). Similarly, extensor moment potentiation of the ankle was greater or tended to be greater than knee (p=0.044) and hip (p=0.051) in young adults. We noted positive relationships between extensor moment potentiation of the knee (r=0.758, p=0.011) and hip (rspearman=0.817, p=0.007) with CMJ JHt in older adults only. JHt potentiation (CMJ/SJ) showed a trend towards positive relationship with the knee moment potentiation (r=0.627, p=0.052) in older adults only. CMJ JHt and JHt potentiation are dictated, in part, by the hip and knee extensor moment potentiation in older adults. Thus, we posit that the propulsion onset is a critical event that can influence jump performance in older adults. None. [ABSTRACT FROM AUTHOR]

Additively manufactured lattices have been adopted in applications ranging from medical implants to aerospace components. For solid AM components, the effect of build parameters has been well studied but comparably little attention has been paid to the influence of build parameters on lattice performance. For this project, the main aim was to evaluate static compressive mechanical performance of regular and stochastic lattices as a function of build parameters. The second aim was to compare strut dimensions of the metal lattice structures as build parameters were changed. Both regular and stochastic lattices were fabricated with a designed strut diameter of either 200 μm or 300 μm on a laser powder bed fusion machine. A range of laser power (140–180 W), scan speed (1700–2100 mm/s), and laser offset (0–45 μm) were used in fabricating each lattice. Compression tests were performed following the ISO 13314 (2011) standard to measure modulus, yield strength, and ultimate compressive strength values. Laser power adjustments produced the most significant effect on lattice performance. A change of 50 W resulted in roughly a 2X increase in maximum load and modulus for both regular and stochastic lattice structures. Regular lattice structures had a higher mechanical response during the mechanical evaluation. Internal strut diameters varied between build parameters as well, with laser offset adjustments producing the most noticeable change in strut geometry between lattice samples. These findings suggest that build parameter optimization, in lieu of using OEM parameters developed for solid structures, is necessary to ensure the optimum mechanical performance of AM lattice structures. [ABSTRACT FROM AUTHOR]

Professions like engineering were a vehicle for social mobility in Australia early in the twentieth century. By the late twentieth century, despite considerable expansions in higher education, it was much harder for young people to enter a trade and then to use their skills and experience to move into professional engineering. The shift in occupation structure in the early twentieth century, when professions - including engineering - grew rapidly, gave new opportunities to working-class tradespeople to move into professional employment. After the 1960s, when educational norms standardised and professional knowledge became more complex, these pathways narrowed. Motor mechanics, for example, were "trade" engineers who were able to move into professional engineering early in the twentieth century in ways that were extensively limited by the end of the century. This article uses engineering as a case study to consider institutional changes, including the growth of middle-class unions and the increased share of education carried by Australian universities, which made access to professional occupations more difficult for working-class tradespeople from the 1960s onwards. This helps us to identify the emergence of a new kind of class solidarity among professionals in the mid-twentieth century, with which they developed strategies to win rights for themselves, but sometimes at the expense of working-class interests. [ABSTRACT FROM AUTHOR]

Much has been written in the last 40 years on how bones heal and why they may not heal. Previously the attention has been focused on a combination of biology and/or mechanics playing a role in non-union of fractures. The authors will give their, clinically experienced and biased, perspective on why it is all about getting the mechanics right and how and why the mechanics change during the healing process. This will help understanding and management of fracture healing and the management of delayed- and non-union. Careful respect is always given to the biology. [ABSTRACT FROM AUTHOR]

The mechanical environment of the joint during dynamic activity plays a significant role in osteoarthritis processes. Understanding how the magnitude, pattern and duration of joint-specific loading features contribute to osteoarthritis progression and response to treatment is a topic of on-going relevance. This narrative review synthesizes evidence from recent papers that have contributed to knowledge related to three identified emerging subthemes: 1) the role of the joint mechanical environment in osteoarthritis pathogenesis, 2) joint biomechanics as an outcome to arthroplasty treatment of osteoarthritis, and 3) methodological trends for advancing our knowledge of the role of biomechanics in osteoarthritis. Rather than provide an exhaustive review of a broad area of research, we have focused on evidence this year related to these subthemes. New research this year has indicated significant interest in using biomechanics investigations to understand structural vs clinical progression of osteoarthritis, the role and interaction in the three-dimensional loading environment of the joint, and the contribution of muscle activation and forces to osteoarthritis progression. There is ongoing interest in understanding how patient variability with respect to gait biomechanics influences arthroplasty surgery outcomes, and subgroup analyses have provided evidence for the potential utility in tailored treatment approaches. Finally, we are seeing a growing trend in the application of translational biomechanics tools such as wearable inertial measurement units for improved integration of biomechanics into clinical decision-making and outcomes assessment for osteoarthritis. [ABSTRACT FROM AUTHOR]

Correcting severe tooth rotations can be challenging. There are many ways to de-rotate teeth with fixed or removable appliances. Mechanically, the best and most effective way is one that produces a two-force couple system to rotate a tooth around its centre of rotation (longitudinal axis). The aim of this article was to introduce a simple and efficient technique using a closed coil to correct localised tooth rotations in the early alignment stage, utilising a simple two-force couple system. Furthermore, some of the biomechanical principles concerning de-rotation will be revisited. [ABSTRACT FROM AUTHOR]

Background: Work-related Musculoskeletal disorder (WMSDs) are multifactorial occupational disorders, having high morbidity and economic cost. Heavy engineering maintenance personnel involved in manual material handling, physical load with awkward posture poses high risk of WMSDs. Objectives: This study investigates the prevalence of work-related Musculoskeletal disorder (WMSD) among Indian defence personnel involved in heavy engineering maintenance work. Setting and Design: A cross-sectional survey was conducted with participant consents. Materials and Methods: 379 defence personnel involved in heavy engineering maintenance task were assessed for WMSDs, using NMQ. The effect of risk factors such as age, working hours, BMI, smoking and type of job on WMSDs was analysed. Statistical Analysis: Data analysis was done using using logistic regression with SPSS version 14. Results: 67.54 % personnel (N=379) reported WMSDs with total of 704 WMSDs. 51.45% reported multiple WMSDs and 16.09% had single WMSDs. Highest WMSDs were reported in low back (44.85%), followed by knee (28.23%), elbow/forearm (15.83%), ankle/foot (22.95%), shoulder (18.46%), upper back (18.46%), neck (15.83%) and wrist/fingers (12.92%). Long working hours (p=0. 000; OR=1.83, 1.58-2.12) and smoking habits (p=0.000; OR=5.52, 3.43-8.48) are significantly correlated with WMSDs. Automobile me chanics (p=.045; OR=2.64, 95% CI=1.04-6.72) and welders (p= 0.034; OR =2.32, 95% CI = 1.21 - 4.36) are at higher risk of WMSDs. Conclusion: There is a high prevalence of WMSDs among Indian defence mechanics. It is suggested that ergonomics training is required for maintenance workers. The detrimental effect of smoking is also noted with the prevalence of WMSDs. [ABSTRACT FROM AUTHOR]

Objective: To assess the potential of using ΔT2 as an indirect index of cartilage strain by quantifying the relationship between local in situ compressive strain and ΔT2 through the full depth of human tibial and femoral articular cartilage.Design: Osteochondral samples (n = 4) of human tibial and femoral cartilage were harvested from cadavers and imaged in a Bruker 7T research MRI scanner under increasing displacement-controlled compressive strains. T2 was calculated for 3D double echo steady state (DESS) image volumes at each strain level. A decaying exponential model estimated local, depth-dependent strains. Strained image volumes were non-linearly warped back to their unloaded configurations and ΔT2 was calculated by image subtraction. Linear modeling assessed local relationships between strain and ΔT2.Results: Bulk average tibial T2 was 13.2 ms for unstrained cartilage and ranged from 13.0 to 13.1 ms under strain; femoral T2 was 14.0 ms for unstrained cartilage and ranged from 13.5 to 14.8 ms under strain. Local ΔT2 in strained cartilage varied with depth. Linear modeling revealed significant correlations between in situ strain and ΔT2 for both tibial and femoral cartilage; correlation coefficients were higher for tibial cartilage.Conclusions: Changes in bulk average T2 are unsuitable as a quantitative surrogate measure of cartilage strain because bulk averaging masks important local variations. High-resolution measures of local ΔT2 have potential value as a surrogate for strain; however, their value is limited until we fully understand the influence of factors like age, joint surface and degeneration on the strain vs T2 relationship. [ABSTRACT FROM AUTHOR]

Mechanics is the branch of physics that deals with the effect of energy and forces on objects. Newton's laws of motion are three physical laws that together describe the relationship between an object and the forces acting upon it, and its motion in response to these forces. Motion can be mathematically described by magnitude, displacement, velocity and acceleration. Work is done when a force acts on an object resulting in its motion. Energy is required for doing work. Power is the rate at which work is done. [ABSTRACT FROM AUTHOR]

Mechanics play a critical - but not sole - role in the pathogenesis of osteoarthritis, and recent research has highlighted how mechanical constructs are relevant at the cellular, joint, and whole-body level related to osteoarthritis outcomes. This review examined papers from April 2018 to April 2019 that reported on the role of mechanics in osteoarthritis etiology, with a particular emphasis on studies that focused on the interaction between movement and tissue biomechanics with other clinical outcomes relevant to the pathophysiology of osteoarthritis. Studies were grouped by themes that were particularly prevalent from the past year. Results of the search highlighted the large exposure of knee-related research relative to other body areas, as well as studies utilizing laboratory-based motion capture technology. New research from this past year highlighted the important role that rate of exerted loads and rate of muscle force development - rather than simply force capacity (strength) - have in OA etiology and treatment. Further, the role of muscle activation patterns in functional and structural aspects of joint health has received much interest, though findings remain equivocal. Finally, new research has identified potential mechanical outcome measures that may be related to osteoarthritis disease progression. Future research should continue to combine knowledge of mechanics with other relevant research techniques, and to identify mechanical markers of joint health and structural and functional disease progression that are needed to best inform disease prevention, monitoring, and treatment. [ABSTRACT FROM AUTHOR]

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We study the analog of Snell's law for particles moving across the interface of two regions with two different potential energies, from two different points of view. First, a simple demonstration involving marbles and a potential step is shown. Then, from a theoretical point of view, this law describing mechanical refraction is derived from the Maupertuis and Jacobi variational principles, in close analogy with the well known derivation of Snell's law for refraction from Fermat's least time principle. Finally, the relativistic version of mechanical refraction is obtained by the Maupertuis principle, by trading the Newtonian dispersion relation with the relativistic one. The pedagogical significance of this treatment is discussed. [ABSTRACT FROM AUTHOR]

The development of hair loss associated with headgear use is a rare phenomenon. Pressure alopecia is a condition characterised by localised, non-scarring hair loss attributed to a mechanical cause. Factors such as prolonged periods of peri- and postoperative immobility have been implicated, as well as immunological and genetic predisposing factors. If the mechanical trauma is very prolonged, there is a risk of permanent follicle damage due to tissue hypoxia. A 13-year-old boy wore high-pull headgear as part of his orthodontic management. Within four weeks of headgear wear, localised areas of hair loss were seen corresponding with the areas of contact with the force delivery modules of the headgear. The patient experienced bullying at school as a result of this hair loss. Hair regrowth resumed after headgear use was discontinued, therefore confirming the diagnosis of temporary pressure alopecia. Temporary pressure alopecia is a rare side effect of orthodontic headgear. Alopecia can negatively impact an individual's psychosocial wellbeing; therefore, caution should be taken to avoid prolonged or excessive pressure in susceptible individuals and headgear patients should be regularly monitored. [ABSTRACT FROM AUTHOR]

The basic collagen fibril structure of tendons continues to be debated in the literature. Some studies have proposed that collagen fibrils are longitudinally discontinuous, with the load-bearing ability of tendon dependent on interfibrillar shear strength. Other evidence indicates that collagen fibrils are probably structurally continuous, running uninterrupted from osteotendinous to myotendinous junction. In this study we explored the question of collagen fibril continuity in tendon by examining fibril response to tendon loading. Tendons were subjected to high stress and/or long duration tensile loading routines, after which we examined the ultrastructure of the tendons using differential scanning calorimetry and scanning electron microscopy, comparing the results from the loaded tendons to control samples taken from the same tendons prior to loading. Our results show that under ramp loading, collagen fibril damage begins near the end of the linear region in the stress-strain response (i.e., near the yield point). When tendons are allowed to gradually elongate under static load, tendon rupture is caused by failure of collagen fibrils, not uncontrolled slippage between fibrils. Our findings indicate that the collagen fibrils of tendon are at least sufficiently long to be mechanically continuous, meaning that tensile failure of tendon does not occur as the result of uncontrolled slippage between fibrils, but by failure of the fibrils themselves. [ABSTRACT FROM AUTHOR]