Knifefish turning control and hydrodynamics during forward swimming.

Rapid turning and swimming contribute to ecologically important behaviors in fishes such as predator avoidance, prey capture, mating and the navigation of complex environments. For riverine species, such as knifefishes, turning behaviors may also be important for navigating locomotive perturbations caused by turbulent flows. Most research on fish maneuvering focuses on fish with traditional fin and body morphologies, which primarily use body bending and the pectoral fins during turning. However, it is uncertain how fishes with uncommon morphologies are able to achieve sudden and controllable turns. Here, we studied the turning performance and the turning hydrodynamics of the black ghost knifefish (Apteronotus albifrons, N=6) which has an atypical elongated ribbon fin. Fish were filmed while swimming forward at ∼2 body lengths s-1 and feeding from a fixed feeder (control) and an oscillating feeder (75 Hz) at two different amplitudes. 3D kinematic analysis of the body revealed the highest pitch angles and lowest body bending coefficients during steady swimming. Low pitch angle, high maximum yaw angles and large body bending coefficients were characteristic of small and large turns. Asynchrony in pectoral fin use was low during turning; however, ribbon fin wavelength, frequency and wave speed were greatest during large turns. Digital particle image velocimetry (DPIV) showed larger counter-rotating vortex pairs produced during turning by the ribbon fin in comparison to vortices rotating in the same direction during steady swimming. Our results highlight the ribbon fin's role in controlled rapid turning through modulation of wavelength, frequency and wave speed.

Beyond the Kármán gait: knifefish swimming in periodic and irregular vortex streets.

Neotropical freshwater fishes such as knifefishes are commonly faced with navigating intense and highly unsteady streams. However, our knowledge on locomotion in apteronotids comes from laminar flows, where the ribbon fin dominates over the pectoral fins or body bending. Here, we studied the 3D kinematics and swimming control of seven black ghost knifefish (Apteronotus albifrons) moving in laminar flows (flow speed U∞≈1-5 BL s-1) and in periodic vortex streets (U∞≈2-4 BL s-1). Two different cylinders (∼2 and ∼3 cm diameter) were used to generate the latter. Additionally, fish were exposed to an irregular wake produced by a free oscillating cylinder (∼2 cm diameter; U∞≈2 BL s-1). In laminar flows, knifefish mainly used their ribbon fin, with wave frequency, speed and acceleration increasing with U∞. In contrast, knifefish swimming behind a fixed cylinder increased the use of pectoral fins, which resulted in changes in body orientation that mimicked steady backward swimming. Meanwhile, individuals behind the oscillating cylinder presented a combination of body bending and ribbon and pectoral fin movements that counteract the out-of-phase yaw oscillations induced by the irregular shedding of vortices. We corroborated passive out-of-phase oscillations by placing a printed knifefish model just downstream of the moving cylinder, but when placed one cylinder diameter downstream, the model oscillated in phase. Thus, the wake left behind an oscillating body is more challenging than a periodic vortex shedding for an animal located downstream, which may have consequences on inter- and intra-specific interactions.

Effects of hypoxia on swimming and sensing in a weakly electric fish.

Low dissolved oxygen (hypoxia) can severely limit fish performance, especially aerobically expensive behaviours including swimming and acquisition of sensory information. Fishes can reduce oxygen requirements by altering these behaviours under hypoxia, but the underlying mechanisms can be difficult to quantify. We used a weakly electric fish as a model system to explore potential effects of hypoxia on swim performance and sensory information acquisition, which enabled us to non-invasively record electric signalling activity used for active acquisition of sensory information during swimming. To quantify potential effects of hypoxia, we measured critical swim speed (Ucrit) and concurrent electric signalling activity under high- and low-dissolved oxygen concentrations in a hypoxia-tolerant African mormyrid fish, Marcusenius victoriae Fish were maintained under normoxia for 6 months prior to experimental treatments, and then acclimated for 8 weeks to normoxia or hypoxia and tested under both conditions (acute: 4 h exposure). Acute hypoxia exposure resulted in a significant reduction in both Ucrit and electric signalling activity in fish not acclimated to hypoxia. However, individuals acclimated to chronic hypoxia were characterized by a higher Ucrit under both hypoxia and normoxia than fish acclimated to normoxia. Following a 6 month re-introduction to normoxia, hypoxia-acclimated individuals still showed increased performance under acute hypoxic test conditions, but not under normoxia. Our results highlight the detrimental effects of hypoxia on aerobic swim performance and sensory information acquisition, and the ability of fish to heighten aerobic performance through acclimation processes that can still influence performance even months after initial exposure.

The Pretravel Consultation.

Key components of the pretravel consultation include intake questions regarding the traveler's anticipated itinerary and medical history; immunizations; malaria prophylaxis; and personal protection measures against arthropod bites, traveler's diarrhea, and injury. Most vaccinations that are appropriate for international travelers are included in the routine domestic immunization schedule; only a few travel-specific vaccines must also be discussed. The most common vaccine-preventable illnesses in international travelers are influenza and hepatitis A. Malaria prophylaxis should be offered to travelers to endemic regions. Personal protection measures, such as applying an effective insect repellent to exposed skin and permethrin to clothing and using a permethrin-impregnated bed net, should be advised for travelers to the tropics. Clinicians should offer an antibiotic prescription that travelers can take with them in case of traveler's diarrhea. Additional topics to address during the pretravel consultation include the risk of injury from motor vehicle crashes and travel-specific risks such as altitude sickness, safe sex practices, and emergency medical evacuation insurance.

Addition of a Second Calcaneal Pin for Spanning Ankle External Fixation.

Spanning ankle external fixation is a commonly used technique for the treatment of fractures of the lower extremity. Traditionally, a single pin is placed in the safe zone of the calcaneus to provide a point of traction for fracture reduction and stabilization. Complications include infection and pin loosening with subsequent loss of fracture reduction. We aim to highlight the benefits and techniques of adding a second calcaneal pin to reduce the likelihood of infection, pin loosening, and possible loss of fracture reduction. Using the standard medial-to-lateral placement technique, two centrally threaded Schanz pins were placed within the safe zone of the calcaneus approximately 2 cm apart and were connected by clamps and a short carbon fiber rod. The remainder of the external fixation apparatus is assembled using a standard technique after obtaining fracture reduction. There is an increased incidence of infection and pin loosening with decreased bone quality and a longer duration within an external fixator. The addition of a second calcaneal pin can be used to reduce the incidence of pin loosening and associated sequela, especially in patients with decreased bone quality, thus improving outcomes for patients undergoing spanning ankle external fixation.

Peer-Reviewed Publications by Successfully Matched Orthopedic Surgery Residency Applicants in the 2022-2023 Match.

BACKGROUND: The Orthopaedic Surgery Match is highly competitive, with more applicants than residency spots. With the Step 1 Exam moving to a pass/fail result, residency programs and applicants have fewer objective data to determine applicants' relative competitiveness. Through this study, we sought to provide the mean number of accepted publications on PubMed a successfully matched orthopedic surgery applicant has by the time of submission of their application. MATERIALS AND METHODS: Orthopedic surgery residency programs participating in the National Resident Matching Program were identified by their ranking on the Doximity Residency Navigator. Each program's intern class and their medical schools were identified. Their names were searched in PubMed and Scopus and articles with their name and affiliations were recorded. RESULTS: In total, 877 orthopedic surgery interns published a mean of 3.30±5.27 articles each on PubMed. They were first or second author on 1.44±2.58, and 1.96±3.89 publications were related to orthopedic surgery. There were no statistical differences between degree, sex, or residency program rank from the Doximity Residency Navigator. The mean number of publications from a successful applicant was approximately 3. There was a great range in the number of publications, and 27.3% of successful applicants did not have a single publication. CONCLUSION: Future applicants and programs can use this number to gauge relative research output. [Orthopedics. 202x;4x(x):xx-xx.].

Developing the Diagnostic Interview for Adolescents and Adults with Mild/Moderate Intellectual Disabilities: An interview schedule of mental disorders (DIAAID).

Introduction: Young people with intellectual disabilities (ID) are at an increased risk for experiencing mental health issues compared to their peers without disabilities. Further, there are limited resources available to help accurately assess mental health disorders and that are accessible for adolescents with ID. Method: This paper describes the iterative development and pilot testing of the Diagnostic Interview for Adolescents and Adults with Intellectual Disabilities (DIAAID). The authors utilized Evidence Center Design and Universal Design principals to develop the DIAAID; a multi-informant diagnostic interview. Results: The DIAAID development resulted in the creation of 15 adolescents disorder interviews and 24 caregiver disorder interviews. Preliminary results suggest that the DIAAID is a feasible and accessible diagnostic interview for adolescents with ID and their caregivers. Discussion: Lessons learned from DIAAID implementation and future areas research are discussed.

Pediatric Axial Ewing Sarcoma: A Retrospective Population-Based Survival Analysis.

INTRODUCTION: Ewing sarcomas of the axial skeleton represent a notable challenge for clinicians because of their aggressive presentation and tendency to obstruct neurovascular structures; however, little data exist regarding axial tumors in children. This study is the first population-based analysis assessing treatment regimens for axial Ewing sarcomas and their effects on cancer-specific survival and overall survival (OS). METHODS: Data from 2004 to 2019 were collected for all patients aged 1 to 24 years from the Surveillance, Epidemiology, and End Results (SEER) database. Primary groups included pelvic tumors, thoracic tumors, and vertebral tumors. Chi-squared and Kaplan-Meier tests were used to assess associations between demographic variables, clinical and treatment characteristics, and patient survival. RESULTS: Pelvic tumors were most common, and 49.7% received chemotherapy/radiation. Vertebral tumors were least common, and 56.7% received chemotherapy/surgery/radiation. 53.5% of thoracic tumors received chemotherapy/surgery. Surgery was most common for thoracic tumors (80.2%) and rare for pelvic tumors (38.9%). Radiation therapy was most common for vertebral tumors (83.6%) and least common for thoracic tumors (36.0%). Pelvic tumors exhibited the lowest OS (1-year, 5-year, and 10-year OS: 96%, 70%, and 59%), followed by thoracic tumors (1-year, 5-year, and 10-year OS: 97%, 79%, and 66%) and vertebral tumors (1-year, 5-year, and 10-year OS: 92%, 77%, and 68%). CONCLUSION: This study underpins the importance of both early detection and chemotherapy-based multimodal therapy in the treatment of axial Ewing sarcoma in a pediatric population. A comparatively large decline in OS was observed between 5 and 10 years for patients with thoracic tumors, and this cohort's 10-year OS has not improved when compared with a similar SEER cohort from 1973 to 2011. Despite a growing body of research supporting definitive radiation therapy, a notable portion of patients with pelvic Ewing sarcoma did not receive radiation, representing an unmet need for this population.

Prey processing in the Siamese fighting fish (Betta splendens).

We studied prey processing in the Siamese fighting fish (Betta splendens), involving slow, easily observed head-bobbing movements, which were compared with prey processing in other aquatic feeding vertebrates. We hypothesized that head-bobbing is a unique prey-processing behaviour, which alternatively could be structurally and functionally analogous with raking in basal teleosts, or with pharyngognathy in neoteleosts. Modulation of head-bobbing was elicited by prey with different motility and toughness. Head-bobbing involved sustained mouth occlusion and pronounced cranial elevation, similar to raking. However, the hyoid and pectoral girdle were protracted, and not retracted as in both raking and pharyngognathy. High-speed videofluoroscopy of hyoid movements confirmed that head-bobbing differs from other known aquatic prey-processing behaviours. Nevertheless, head-bobbing and other prey-processing behaviours converge on a recurrent functional theme in the trophic ecology of aquatic feeding vertebrates; the use of intraoral and oropharyngeal dentition surfaces to immobilize, reduce and process relatively large, tough or motile prey. Prey processing outside the pharyngeal region has not been described for neoteleosts previously, but morphological evidence suggests that relatives of Betta might use similar processing behaviours. Thus, our results suggest that pharyngognathy did not out-compete ancestral prey-processing mechanisms completely during the evolution of neoteleosts.

Intercalary Tricortical Iliac Crest Graft for Treatment of Midclavicle Nonunion With Bone Loss: Two Case Reports and Review of Literature.

Several articles support the use of cancellous iliac crest bone grafting in the treatment of clavicle nonunion; however, there is very little literature on the use of tricortical iliac crest grafts in the setting of clavicle nonunion with bone loss. When it has been studied, tricortical grafting has been shown to produce radiologically confirmed union in the clavicle, leaving patients satisfied with the ultimate outcome. We present two cases of clavicle fracture nonunion successfully treated with tricortical interposition bone grafting. In the first case, a 45-year-old female presented with an atrophic left midshaft clavicle fracture nonunion with failed hardware that had undergone two previous attempts at fixation without achieving union. She was treated with a structural interposition iliac crest bone graft with plate fixation and regained full painless function of the arm with radiographic fracture union. In the second case, a 50-year-old male presented after a left midshaft clavicle fracture that had undergone acute stabilization, followed by revision for nonunion that was unsuccessful, resulting in persistent nonunion with bone loss. He was treated with a tricortical iliac crest bone graft and plate fixation. Cultures from the time of surgery did grow Staphylococcus epidermidis and Propionibacterium acnes, and he was treated with intravenous vancomycin for six weeks. The patient's clavicle went on to union and he regained full, painless function by his six-month follow-up visit. These cases demonstrate the use of tricortical interposition bone grafting with compression plating as a viable option for rare instances in which previous surgical intervention has failed to progress a midshaft clavicle fracture to union.

Contralateral Gluteal Compartment Syndrome After Prolonged Use of a Fracture Table in a Scissoring Position: A Case Report.

CASE: A 62-year-old Caucasian man presented with a comminuted subtrochanteric fracture after a low-energy fall. Physical examination postoperatively revealed a firm hard gluteal compartment in the contralateral buttocks. The patient underwent a fasciotomy, using the Kocher-Langenbeck approach, to release the gluteus maximus and lateral thigh fascia. At the most recent 6-month follow-up, gluteal function was intact with no long-term sequelae from compartment syndrome. CONCLUSION: Prolonged positioning on a fracture table can result in gluteal compartment syndrome of the contralateral extremity.

Comparison of Risk Factors Between Syndesmotic Screws With and Without Breakage.

Background Screw fixation continues to be a commonly used treatment for syndesmotic disruption; however, screw breakage remains a complication post-fixation. Despite this complication, investigation on the variability of surgical placement in conjunction with syndesmotic screw characteristics affecting breakage has not been fully elucidated. The purpose of this study is to compare patients with syndesmotic screw breakage versus those with intact screws based on surgically controlled variables. Methods A total of 176 patients and 260 syndesmotic screws were included in the study, 88 patients each with and without broken syndesmotic screws. A retrospective analysis of patients who underwent syndesmotic screw fixation was performed. Patients with syndesmotic screw breakage were compared to those with intact screws. Screw width and length, the number of screws used, fracture type, and the number of cortices for fixation were all collected. Further analysis included radiographic measurement of syndesmotic screw angle and height of placement above the tibial plafond. Results Decreased screw width, increased number of screws used, and younger age were all associated with increased rates of screw breakage (p < .001, p = .019, p = 0.020). No statistical difference was appreciated between groups based on screw length, number of cortices used, or angle relative to the tibial plafond (p = .2432, p = .4699, p = .9233). Conclusion Higher placement of syndesmotic screws above the tibiotalar joint, specifically greater than 20 mm above the tibial plafond, increases the screw breakage rate. Decreased screw width, increasing numbers of screws used, and younger age were all also associated with increased rates of screw breakage. No difference was appreciated based on the screw angle relative to the tibial plafond.

DETECT--a density estimation tool for enzyme classification and its application to Plasmodium falciparum.

MOTIVATION: A major challenge in genomics is the accurate annotation of component genes. Enzymes are typically predicted using homology-based search methods, where the membership of a protein to an enzyme family is based on single-sequence comparisons. As such, these methods are often error-prone and lack useful measures of reliability for the prediction. RESULTS: Here, we present DETECT, a probabilistic method for enzyme prediction that accounts for the sequence diversity across enzyme families. By comparing the global alignment scores of an unknown protein to those of all known enzymes, an integrated likelihood score can be readily calculated, ranking the reaction classes relevant for that protein. Comparisons to BLAST reveal significant improvements in enzyme annotation accuracy. Applied to Plasmodium falciparum, we identify potential annotation errors and predict novel enzymes of therapeutic interest. AVAILABILITY: A standalone application is available from the website: http://www.compsysbio.org/projects/DETECT/

Rhythmic chewing with oral jaws in teleost fishes: a comparison with amniotes.

Intra-oral prey processing (chewing) using the mandibular jaws occurs more extensively among teleost fishes than previously documented. The lack of muscle spindles, gamma-motoneurons and periodontal afferents in fishes makes them useful for testing hypotheses regarding the relationship between these sensorimotor components and rhythmic chewing in vertebrates. Electromyography (EMG) data from the adductor mandibulae (AM) were used to quantify variation in chew cycle duration in the bowfin Amia, three osteoglossomorphs (bony-tongues), four salmonids and one esocid (pike). All species chewed prey using their oral jaw in repetitive trains of between 3 and 30 consecutive chews, a pattern that resembles cyclic chewing in amniote vertebrates. Variance in rhythmicity was compared within and between lineages using coefficients of variation and Levene's test for homogeneity of variance. These comparisons revealed that some teleosts exhibit degrees of rhythmicity that are comparable to mammalian mastication and higher than in lepidosaurs. Moreover, chew cycle durations in fishes, as in mammals, scale positively with mandible length. Chewing among basal teleosts may be rhythmic because it is stereotyped and inflexible, the result of patterned interactions between sensory feedback and a central pattern generator, because the lack of a fleshy tongue renders jaw-tongue coordination unnecessary and/or because stereotyped opening and closing movements are important for controlling fluid flow in the oral cavity.

Knifefish's suction makes water boil.

We discovered that knifefish (Apteronotus albifrons) during suction feeding can produce millimeter-sized cavitation bubbles and flow accelerations up to ~ 450 times the acceleration of gravity. Knifefish may use this powerful suction-induced cavitation to cause physical damage on prey hiding in narrow refuges, therefore facilitating capture.

Deploying Big Data to Crack the Genotype to Phenotype Code.

Mechanistically connecting genotypes to phenotypes is a longstanding and central mission of biology. Deciphering these connections will unite questions and datasets across all scales from molecules to ecosystems. Although high-throughput sequencing has provided a rich platform on which to launch this effort, tools for deciphering mechanisms further along the genome to phenome pipeline remain limited. Machine learning approaches and other emerging computational tools hold the promise of augmenting human efforts to overcome these obstacles. This vision paper is the result of a Reintegrating Biology Workshop, bringing together the perspectives of integrative and comparative biologists to survey challenges and opportunities in cracking the genotype to phenotype code and thereby generating predictive frameworks across biological scales. Key recommendations include promoting the development of minimum "best practices" for the experimental design and collection of data; fostering sustained and long-term data repositories; promoting programs that recruit, train, and retain a diversity of talent; and providing funding to effectively support these highly cross-disciplinary efforts. We follow this discussion by highlighting a few specific transformative research opportunities that will be advanced by these efforts.

Functional morphology and biomechanics of the tongue-bite apparatus in salmonid and osteoglossomorph fishes.

The tongue-bite apparatus and its associated musculoskeletal elements of the pectoral girdle and neurocranium form the structural basis of raking, a unique prey-processing behaviour in salmonid and osteoglossomorph fishes. Using a quantitative approach, the functional osteology and myology of this system were compared between representatives of each lineage, i.e. the salmonid Salvelinus fontinalis (N = 10) and the osteoglossomorph Chitala ornata (N = 8). Divergence was found in the morphology of the novel cleithrobranchial ligament, which potentially relates to kinematic differences between the raking lineage representatives. Salvelinus had greater anatomical cross-sectional areas of the epaxial, hypaxial and protractor hyoideus muscles, whereas Chitala had greater sternohyoideus and adductor mandibulae mass. Two osteology-based biomechanical models (a third-order lever for neurocranial elevation and a modified four-bar linkage for hyoid retraction) showed divergent force/velocity priorities in the study taxa. Salvelinus maximizes both force (via powerful cranial muscles) and velocity (through mechanical amplification) during raking. In contrast, Chitala has relatively low muscle force but more efficient force transmission through both mechanisms compared with Salvelinus. It remains unclear if and how behavioural modulation and specializations in the post-cranial anatomy may affect the force/velocity trade-offs in Chitala. Further studies of tongue-bite apparatus morphology and biomechanics in a broader species range may help to clarify the role that osteology and myology play in the evolution of behavioural diversity.

Type IV tibial tubercle fracture-Salter-Harris type II variant.

Fractures about the tibial tubercle are uncommon fracture patterns, seen most often in adolescent males as they approach skeletal maturity. Compartment syndrome has a high association with these fractures requiring close monitoring, and a heightened level of suspicion. Tibial tubercle fractures are typically stratified using the Ogden classification. The type of intra-articular involvement and degree of displacement guide appropriate treatment. This report highlights a 14-year-old male patient who suffered a type IV tibial tubercle fracture with a unique Salter-Harris II, or transitional, component posteriorly that was unable to be closed reduced and developed compartment syndrome. He underwent fasciotomy, open reduction, and temporary external fixation. Once the status of the soft tissues improved, he underwent staged open reduction and internal fixation with skin grafting. The patient's fracture and soft tissues healed and he currently ambulates without assistance or pain, and has returned to all desired activities including competitive sports.

Does air pollution contribute to travelers' illness and deaths?-evidence from a case report and need for further studies.

Annual increases in global travel have resulted in more individuals being exposed to varying environmental conditions abroad and, thereby, subject to air pollution related health risks. Individuals who travel abroad may be exposed to varying levels of air pollution within a matter of hours. We wish to consider whether exposure to air pollution could be a significant contributor to the risk of illness and death in travelers, particularly those who travel to highly polluted cities. We report the findings of a study in which the peak expiratory flow (PEF) of a traveler decreased in Shanghai relative to baseline in New York City; the decline in PEF correlated to concentration of particulate matter (PM2.5). We discuss the health implication of these results on global travel.

Hydrodynamics of prey capture in sharks: effects of substrate.

In suction feeding, a volume of water is drawn into the mouth of a predator. Previous studies of suction feeding in fishes have shown that significant fluid velocities are confined to a region within one mouth width from the mouth. Therefore, the predator must be relatively close to the prey to ensure capture success. Here, theoretical modelling is combined with empirical data to unravel the mechanism behind feeding on a substrate. First, we approached the problem theoretically by combining the stream functions of two sinks. Computational fluid dynamics modelling is then applied to make quantitative predictions regarding the effects of substrate proximity on the feeding hydrodynamics of a benthic shark. An oblique circular cylinder and a shark head model were used. To test the models, we used digital particle image velocimetry to record fluid flow around the mouth of white-spotted bamboo sharks, Chiloscyllium plagiosum, during suction feeding on the substrate and in the water column. Empirical results confirmed the modelling predictions: the length of the flow field can be doubled due to passive substrate effects during prey capture. Feeding near a substrate extends the distance over which suction is effective and a predator strike can be effective further from the prey.