Fish couple forecasting with feedback control to chase and capture moving prey.

Predator-prey interactions are fundamental to ecological and evolutionary dynamics. Yet, predicting the outcome of such interactions-whether predators intercept prey or fail to do so-remains a challenge. An emerging hypothesis holds that interception trajectories of diverse predator species can be described by simple feedback control laws that map sensory inputs to motor outputs. This form of feedback control is widely used in engineered systems but suffers from degraded performance in the presence of processing delays such as those found in biological brains. We tested whether delay-uncompensated feedback control could explain predator pursuit manoeuvres using a novel experimental system to present hunting fish with virtual targets that manoeuvred in ways that push the limits of this type of control. We found that predator behaviour cannot be explained by delay-uncompensated feedback control, but is instead consistent with a pursuit algorithm that combines short-term forecasting of self-motion and prey motion with feedback control. This model predicts both predator interception trajectories and whether predators capture or fail to capture prey on a trial-by-trial basis. Our results demonstrate how animals can combine short-term forecasting with feedback control to generate robust flexible behaviours in the face of significant processing delays.

The quadriceps Femoris allograft as an extension of the Angiosome concept: A cadaveric-based anatomical feasibility study.

BACKGROUND: Vascularised composite allo-transplantation (VCA) is emerging as a tailored approach for complex tissue reconstruction. This study focuses on the quadriceps VCA as a potential solution for tissue repair, following trauma, necrotising fasciitis/myositis, or tumor ablation. METHODS: Dissections were undertaken in 10 adult cadaveric lower limbs to characterize the blood supply to the quadriceps femoris for en bloc muscle allo-transplantation. A mock cadaveric transplantation was performed to (a) define the best neurovascular VCA design and (b) test the feasibility of the procedure. A review of 54 archival radiograph studies from the institution was also performed to further evaluate the muscle vasculature. RESULTS: In two lower limbs, the quadriceps VCA was harvested designed on the common and superficial femoral vessels and nerve, which revealed a lengthy and bloody dissection, especially of the veins, which could increase clinically with the inability to use a tourniquet for most of the dissection. However, review of our previous archival studies showed that all four quadriceps muscles are supplied within the lateral circumflex femoral angiosome. In a further eight lower limbs, the quadriceps femoris muscle group consistently received its blood supply from the lateral circumflex femoral angiosome, verified by selective lead oxide injections of this artery. The vastus medialis appeared to have a more tenous blood supply distally based on this angiosome. A successful mock cadaveric transplant was performed based on this data. CONCLUSIONS: We suggest that the best neuromuscular quadriceps VCA should be (a) designed on the lateral circumflex femoral pedicle, (b) should be raised from distal to proximal, and (c) should include the descending genicular vessels as a potential supplemental supply to vastus medialis, should all four muscles be required.

A systematic review and meta-analysis of locoregional treatments for in-transit melanoma.

BACKGROUND AND OBJECTIVES: In-transit melanoma (ITM) metastases present a therapeutic challenge and management decisions can be difficult. There are multiple treatments available, with differing efficacy, and supported by different levels of evidence. The primary objective was to perform a systematic review and where suitable, a meta-analysis of the literature reporting on the use of locoregional treatments for the management of ITM. METHODS: An independent review was conducted including a comprehensive search of the National Library of Medicine using PubMed, MEDLINE, Embase, and Cochrane Library databases. Key data were tabulated, synthesized and pooled to calculate relevant weighted effect sizes for each therapy using random-effect models. The statistical heterogeneity was calculated using the Higgins' method. RESULTS: Of the initial 32 612 articles identified, 57 original articles satisfied eligibility criteria. Eight treatment modalities were identified comprising: amputation (7); hyperthermic isolated limb perfusion (15); isolated limb infusion (8); carbon dioxide laser (9); PV-10 intralesional therapy (5); IL-2 intralesional therapy (8); imiquimod (7); diphenylcyclopropenone (3). Only amputation and topical imiquimod were suitable for formal meta-analysis. CONCLUSIONS: All of the assessed therapies have significant selection bias. Variable levels of evidence support the ongoing use of locoregional treatments and these may significantly improve disease-free survival.

Tuning hardness in calcite by incorporation of amino acids.

Structural biominerals are inorganic/organic composites that exhibit remarkable mechanical properties. However, the structure-property relationships of even the simplest building unit-mineral single crystals containing embedded macromolecules-remain poorly understood. Here, by means of a model biomineral made from calcite single crystals containing glycine (0-7 mol%) or aspartic acid (0-4 mol%), we elucidate the origin of the superior hardness of biogenic calcite. We analysed lattice distortions in these model crystals by using X-ray diffraction and molecular dynamics simulations, and by means of solid-state nuclear magnetic resonance show that the amino acids are incorporated as individual molecules. We also demonstrate that nanoindentation hardness increased with amino acid content, reaching values equivalent to their biogenic counterparts. A dislocation pinning model reveals that the enhanced hardness is determined by the force required to cut covalent bonds in the molecules.

Primary cutaneous melanoma of the scalp: Patterns of recurrence.

INTRODUCTION: Patients with primary melanoma of the scalp have been reported to have worse disease-related outcomes compared with other anatomical regions. There are few studies in the literature specifically addressing recurrence patterns and treatment outcomes for primary scalp melanoma as a discrete anatomical sub-region. We sought to identify key features adversely influencing disease control and survival and to clarify the role of resection plane, margin, and method of reconstruction in the management of this disease process. METHODS: A retrospective clinical study of medical records was performed evaluating all patients with primary melanoma of the scalp treated at two hospitals in southeast Queensland between 2004 and 2014. RESULTS: A total of 107 patients were eligible for analysis. There were 46 recurrences in 38 patients in the cohort accounting for a recurrence rate of 35.5%. The local recurrence rate was 15.9% with 12 in-transit metastases after diagnosis. Regional and distant recurrence rates were 12.1% and 15%, respectively. At a median follow up of 30.5 months, disease-free survival was 47% and overall survival was also 47%. On multi-variate analysis, the deeper resection plane (sub-galeal) had a lower disease-free survival rate compared with the supra-galeal resection plane (P = 0.032). DISCUSSION: Our results support the hypothesis that primary scalp melanoma represents a unique aggressive subcategory with high rates of in-transit disease and poor disease-related and survival outcomes. There is a need for robust prospective comparative studies to address the significance of resection plane in the management of patients with scalp melanoma.

Adsorption of poly acrylic acid onto the surface of calcite: an experimental and simulation study.

Macromolecular binding to minerals is of great importance in the formation of biofilms, and carboxylate functional groups have been found to play a pivotal role in the functioning of these macromolecules. Here we present both fluorescence time-resolved anisotropy measurements and simulation data on the conformational behaviour and binding of a poly acrylic acid polymer. In solution the polymer exhibits a pH dependent behaviour, with a coiled conformation at a low pH and extended conformation at higher pH values. The polymer is readily adsorbed on the surface of calcite, preferring to bind in an extended conformation, with the strength of the adsorption dependent on the pH and presence of counter ions. We discuss the reasons why the calculated adsorption free energy differs from that obtained from a Langmuir isotherm analysis, showing that they refer to different quantities. The enhanced binding of the extended conformations shows the importance of flexibility in the binding of macromolecules.

Swimming kinematics of rainbow trout behind cylinder arrays: the effect of vortex street periodicity and turbulence kinetic energy.

Fish in the wild often contend with complex flows that are produced by natural and artificial structures. Research into fish interactions with turbulence often investigates metrics such as turbulence kinetic energy (TKE) or fish positional location, with less attention paid to the specific interactions between vortex organization and body swimming kinematics. Here we compare the swimming kinematics of rainbow trout ( Oncorhynchus mykiss ) holding station in flows produced by two different 3 x 5 cylinder arrays. We systematically utilized computational fluid dynamics to generate one array that produced a Kármán vortex street with high vortex periodicity and TKE (KVS array), and another that produced low periodicity and TKE, similar to a parallel vortex street (PVS array). The only difference in swimming kinematics between cylinder arrays was an increased tail beat amplitude in the KVS array. In both cylinder arrays, the tail beat frequency decreased and snout amplitude increased compared with the freestream. The center of mass amplitude was greater in the PVS array than in only the freestream, however, suggesting some buffeting of the body by the fluid. Notably, we did not observe Kármán gaiting in the KVS array as in previous studies. We hypothesize that this is because (1) vorticity was dissipated in the region where fish held station in this study and (2) cylinder arrays produced vortices that were in-line rather than staggered. These results are the first to quantify the kinematics and behavior of fishes swimming in the wake of multiple cylinder arrays, which has important implications for biomechanics, fluid dynamics, and fisheries management. SUMMARY STATEMENT: The swimming kinematics of rainbow trout are largely preserved across two, 3 x 5 cylinder array treatments that differed in vortex periodicity and turbulence kinetic energy.

Protocol for the BONE-RECON trial: a single-arm feasibility trial for critical sized lower limb BONE defect RECONstruction using the mPCL-TCP scaffold system with autologous vascularised corticoperiosteal tissue transfer.

INTRODUCTION: Reconstruction of critical bone defects is challenging. In a substantial subgroup of patients, conventional reconstructive techniques are insufficient. Biodegradable scaffolds have emerged as a novel tissue engineering strategy for critical-sized bone defect reconstruction. A corticoperiosteal flap integrates the hosts' ability to regenerate bone and permits the creation of a vascular axis for scaffold neo-vascularisation (regenerative matching axial vascularisation-RMAV). This phase IIa study evaluates the application of the RMAV approach alongside a custom medical-grade polycaprolactone-tricalcium phosphate (mPCL-TCP) scaffold (Osteopore) to regenerate bone sufficient to heal critical size defects in lower limb defects. METHODS AND ANALYSIS: This open-label, single-arm feasibility trial will be jointly coordinated by the Complex Lower Limb Clinic (CLLC) at the Princess Alexandra Hospital in Woolloongabba (Queensland, Australia), the Australian Centre for Complex Integrated Surgical Solutions (Queensland, Australia) and the Faculty of Engineering, Queensland University of Technology in Kelvin Grove (Queensland, Australia). Aiming for limb salvage, the study population (n=10) includes any patient referred to the CLLC with a critical-sized bone defect not amenable to conventional reconstructive approaches, after discussion by the interdisciplinary team. All patients will receive treatment using the RMAV approach using a custom mPCL-TCP implant. The primary study endpoint will be safety and tolerability of the reconstruction. Secondary end points include time to bone union and weight-bearing status on the treated limb. Results of this trial will help shape the role of scaffold-guided bone regenerative approaches in complex lower limb reconstruction where current options remain limited. ETHICS AND DISSEMINATION: Approval was obtained from the Human Research Ethics Committee at the participating centre. Results will be submitted for publication in a peer-reviewed journal. TRIAL REGISTRATION NUMBER: ACTRN12620001007921.