MODELLING TRANSTIBIAL PROSTHESES FOR SIMULATION

Investigating the effect of a prosthetics size, shape, and stiffness on sports performance requires a theoretical approach, however this requires a more complex representation of the prosthetic beyond those previously adopted. A chain model was used to investigate the level of complexity (n-segments; n=2,3,4) required to reproduce the kinematics and kinetics of a prosthetic during six different movements performed by a unilateral transtibial amputee athlete. The optimal solution was evaluated using an angle-driven simulation model and close agreement (3% RMS difference) was observed between the simulation and recorded performances suggesting the complexity was sufficient. This approach could be employed within theoretical approaches to investigate the cause and effect of prostheses on sporting movements or to custom fit appropriate prostheses for individual athletes

THE EFFECT OF MEASUREMENT ANGLE ON APPROXIMATIONS OF MAXIMUM JOINT TORQUE

The purpose of this study was to investigate the underestimation of maximum knee joint torque using a single joint-angle position for a variety of realistic torque-angle curves. The maximum force production capability of the knee flexors and knee extensors was modelled using literature-based parameters to define a quadratic torque-angle relationship. Model parameters were varied within a normative range and simulated measured torque was compared to true peak torque (model) for a series of commonly tested joint angles. Measurements furthest from the optimal angle for maximum strength were associated with underestimated torques that were 96% and 80% lower than true peak torque. Therefore, it is essential that knee joint torque is measured as close to the optimal angle as possible when attempting to determine maximum strength capability using a single discrete measurement

SURFACE MEASURED ACCELERATIONS DURING CRICKET FAST-BOWLING

The aim of this research was to quantify the magnitude and timing of surface measured accelerations during the fast-bowling action. Eleven males performed 6 maximum velocity deliveries with accelerometers positioned over: both ankles; knees; hips; L5; L1; and the C7 vertebrae. Accelerometer signals exhibited decreased peak and increased time to peak acceleration from the ankle to the C7 sensor. Even when distal accelerations were largest at front foot contact, the body was still able to dissipate more than 90% of the acceleration. Active and passive mechanisms such as joint compliance and spinal compression within the body therefore likely contribute to the progressive attenuation of accelerations. The effects of such compliance on investigations of the intersegmental forces and moments during cricket fast-bowling via inverse dynamics warrants further investigation. KEYWORDS: accelerometer, attenuation, inertial measurement unit, ground reaction force

Passive range of motion of the hips and shoulders and their relationship with ball spin rate in elite finger spin bowlers

Objectives: Investigate rotational passive range of motion of the hips and shoulders for elite finger spin bowlers and their relationship with spin rate. Design: Correlational. Methods: Spin rates and twelve rotational range of motion measurements for the hips and shoulders were collected for sixteen elite male finger spin bowlers. Side to side differences in the rotational range of motion measurements were assessed using paired t-tests. Stepwise linear regression and Pearson product moment correlations were used to identify which range of motion measurements were linked to spin rate. Results: Side to side differences were found with more external rotation (p = 0.039) and less internal rotation (p = 0.089) in the bowling shoulder, and more internal rotation in the front hip (p = 0.041). Total arc of rotation of the front hip was found to be the best predictor of spin rate (r = 0.552, p =  0.027), explaining 26% of the observed variance. Internal rotation of the rear hip (r = 0.466, p =  0.059) and the bowling shoulder (r = 0.476, p =  0.063) were also associated with spin rate. Conclusions: The technique and performance of elite finger spin bowlers may be limited by the passive range of motion of their hips and shoulders. The observed side to side differences may indicate that due to the repetitive nature of finger spin bowling adaptive changes in the rotational range of motion of the hip and shoulder occur

Composition and diversity analysis of the lung microbiome in patients with suspected ventilator-associated pneumonia.

BackgroundVentilator-associated pneumonia (VAP) is associated with high morbidity and health care costs, yet diagnosis remains a challenge. Analysis of airway microbiota by amplicon sequencing provides a possible solution, as pneumonia is characterised by a disruption of the microbiome. However, studies evaluating the diagnostic capabilities of microbiome analysis are limited, with a lack of alignment on possible biomarkers. Using bronchoalveolar lavage fluid (BALF) from ventilated adult patients suspected of VAP, we aimed to explore how key characteristics of the microbiome differ between patients with positive and negative BALF cultures and whether any differences could have a clinically relevant role.MethodsBALF from patients suspected of VAP was analysed using 16s rRNA sequencing in order to: (1) differentiate between patients with and without a positive culture; (2) determine if there was any association between microbiome diversity and local inflammatory response; and (3) correctly identify pathogens detected by conventional culture.ResultsThirty-seven of 90 ICU patients with suspected VAP had positive cultures. Patients with a positive culture had significant microbiome dysbiosis with reduced alpha diversity. However, gross compositional variance was not strongly associated with culture positivity (AUROCC range 0.66-0.71). Patients with a positive culture had a significantly higher relative abundance of pathogenic bacteria compared to those without [0.45 (IQR 0.10-0.84), 0.02 (IQR 0.004-0.09), respectively], and an increased interleukin (IL)-1β was associated with reduced species evenness (rs = - 0.33, p s = 0.28, p = 0.013). Untargeted 16s rRNA pathogen detection was limited by false positives, while the use of pathogen-specific relative abundance thresholds showed better diagnostic accuracy (AUROCC range 0.89-0.998).ConclusionPatients with positive BALF culture had increased dysbiosis and genus dominance. An increased caspase-1-dependent IL-1b expression was associated with a reduced species evenness and increased pathogenic bacterial presence, providing a possible causal link between microbiome dysbiosis and lung injury development in VAP. However, measures of diversity were an unreliable predictor of culture positivity and 16s sequencing used agnostically could not usefully identify pathogens; this could be overcome if pathogen-specific relative abundance thresholds are used

Microbial volatiles as diagnostic biomarkers of bacterial lung infection in mechanically ventilated patients.

BackgroundEarly and accurate recognition of respiratory pathogens is crucial to prevent increased risk of mortality in critically ill patients. Microbial-derived volatile organic compounds (mVOCs) in exhaled breath could be used as non-invasive biomarkers of infection to support clinical diagnosis.MethodsIn this study, we investigated the diagnostic potential of in vitro confirmed mVOCs in the exhaled breath of patients under mechanically ventilation from the BreathDx study. Samples were analysed by thermal desorption-gas chromatography-mass spectrometry (TD-GC-MS).ResultsPathogens from bronchoalveolar lavage (BAL) cultures were identified in 45/89 patients and S. aureus was the most commonly identified pathogen (n = 15). Out of 19 mVOCs detected in the in vitro culture headspace of four common respiratory pathogens (Staphylococcus aureus, Pseudomonas aeruginosa, Klebsiella pneumoniae and Escherichia coli), 14 were found in exhaled breath samples. Higher concentrations of two mVOCs were found in the exhaled breath of patients infected with S. aureus compared to those without (3-methylbutanal p ConclusionsThis study demonstrates the capability of using mVOCs to detect the presence of specific pathogen groups with potential to support clinical diagnosis. Although not all mVOCs were found in patient samples within this small pilot study, further targeted and qualitative investigation is warranted using multi-centre clinical studies

Alterations in T and B cell function persist in convalescent COVID-19 patients

BackgroundEmerging studies indicate that some COVID-19 patients suffer from persistent symptoms including breathlessness and chronic fatigue; however the long-term immune response in these patients presently remains ill-defined.MethodsHere we describe the phenotypic and functional characteristics of B and T cells in hospitalised COVID-19 patients during acute disease and at 3-6 months of convalescence.FindingsWe report that the alterations in B cell subsets observed in acute COVID-19 patients were largely recovered in convalescent patients. In contrast, T cells from convalescent patients displayed continued alterations with persistence of a cytotoxic programme evident in CD8+ T cells as well as elevated production of type-1 cytokines and IL-17. Interestingly, B cells from patients with acute COVID-19 displayed an IL-6/IL-10 cytokine imbalance in response to toll-like receptor activation, skewed towards a pro-inflammatory phenotype. Whereas the frequency of IL-6+ B cells was restored in convalescent patients irrespective of clinical outcome, recovery of IL-10+ B cells was associated with resolution of lung pathology.ConclusionsOur data detail lymphocyte alterations in previously hospitalized COVID-19 patients up to 6 months following hospital discharge and identify 3 subgroups of convalescent patients based on distinct lymphocyte phenotypes, with one subgroup associated with poorer clinical outcome. We propose that alterations in B and T cell function following hospitalisation with COVID-19 could impact longer term immunity and contribute to some persistent symptoms observed in convalescent COVID-19 patients

Bioavailability of Macro and Micronutrients Across Global Topsoils: Main Drivers and Global Change Impacts

Understanding the chemical composition of our planet\u27s crust was one of the biggest questions of the 20th century. More than 100 years later, we are still far from understanding the global patterns in the bioavailability and spatial coupling of elements in topsoils worldwide, despite their importance for the productivity and functioning of terrestrial ecosystems. Here, we measured the bioavailability and coupling of thirteen macro- and micronutrients and phytotoxic elements in topsoils (3–8 cm) from a range of terrestrial ecosystems across all continents (∼10,000 observations) and in response to global change manipulations (∼5,000 observations). For this, we incubated between 1 and 4 pairs of anionic and cationic exchange membranes per site for a mean period of 53 days. The most bioavailable elements (Ca, Mg, and K) were also amongst the most abundant in the crust. Patterns of bioavailability were biome-dependent and controlled by soil properties such as pH, organic matter content and texture, plant cover, and climate. However, global change simulations resulted in important alterations in the bioavailability of elements. Elements were highly coupled, and coupling was predictable by the atomic properties of elements, particularly mass, mass to charge ratio, and second ionization energy. Deviations from the predictable coupling-atomic mass relationship were attributed to global change and agriculture. Our work illustrates the tight links between the bioavailability and coupling of topsoil elements and environmental context, human activities, and atomic properties of elements, thus deeply enhancing our integrated understanding of the biogeochemical connections that underlie the productivity and functioning of terrestrial ecosystems in a changing world