Humans trade off whole-body energy cost to avoid overburdening muscles while walking

Metabolic cost minimization is thought to underscore the neural control of locomotion. Yet, avoiding high muscle activation, a cause of fatigue, often outperforms energy minimization in computational predictions of human gait. Discerning the relative importance of these criteria in human walking has proved elusive, in part, because they have not been empirically decoupled. Here, we explicitly decouple whole-body metabolic cost and 'fatigue-like' muscle activation costs (estimated from electromyography) by pitting them against one another using two distinct gait tasks. When experiencing these competing costs, participants (n = 10) chose the task that avoided overburdening muscles (fatigue avoidance) at the expense of higher metabolic power (p < 0.05). Muscle volume-normalized activation more closely models energy use and was also minimized by the participants' decision (p < 0.05), demonstrating that muscle activation was, at best, an inaccurate signal for metabolic energy. Energy minimization was only observed when there was no adverse effect on muscle activation costs. By decoupling whole-body metabolic and muscle activation costs, we provide among the first empirical evidence of humans embracing non-energetic optimality in favour of a clearly defined neuromuscular objective. This finding indicates that local muscle fatigue and effort may well be key factors dictating human walking behaviour and its evolution

Recent history, current status, conservation and management of native mammalian carnivore species in Great Britain

This is the author accepted manuscript. The final version is available from Wiley via the DOI in this record After historical declines in population sizes and ranges, we compare and contrast the recent history and contemporary variation in the status of Great Britain's eight native mammalian carnivore species from the 1960s to 2017. Wildcat Felis silvestris conservation status is unfavourable and is masked by hybridisation with domestic cats Felis catus. Red foxes Vulpes vulpes remain widespread but are currently declining. European otter Lutra lutra, European pine marten Martes martes and European polecat Mustela putorius populations are characterised by rapid recovery. Otters have almost completely recolonised Great Britain, polecats have expanded their range throughout southern Britain from refugia in Wales and pine martens have expanded their range from the Scottish Highlands. European badgers Meles meles have generally increased in population density. Status assessments of stoats Mustela erminea and weasels Mustela nivalis are data-deficient but available evidence suggests that stoats may have increased while weasels may have declined. Anthropogenic processes influencing carnivore status include legal protections, habitat quality, reintroductions, predator control, pollutants, hybridisation and diseases and their associated control practices. Population effects of contaminants, such as anticoagulant rodenticides, remain poorly characterised. The widespread interface with domestic and feral cats makes the wildcat's situation precarious. Recent declines in rabbit Oryctolagus cuniculus populations are a concern, given that several carnivore species depend on them as food. We conclude that, with the exception of the wildcat, the status of Great Britain's mammalian carnivores has markedly improved since the 1960s. Better understanding of the social aspects of interactions between humans and expanding predator populations is needed if conflict is to be avoided and long-term co-existence with people is to be possible.Vincent Wildlife TrustUniversity of Exete

Adding a toe joint to a prosthesis: walking biomechanics, energetics, and preference of individuals with unilateral below-knee limb loss

Toe joints play an important functional role in able-bodied walking; however, for prosthesis users, the effect of adding a toe joint to a passive prosthetic foot remains largely unknown. The current study explores the kinematics, kinetics, rate of oxygen consumption and user preference of nine individuals with below-knee limb loss. Participants walked on a passive prosthetic foot in two configurations: with a Flexible, articulating toe joint and with a Locked-out toe joint. During level treadmill gait, participants exhibited a decrease in Push-Off work when using the Flexible toe joint prosthesis versus the Locked toe joint prosthesis: 16% less from the prosthesis (p = 0.004) and 10% less at the center of mass level (p = 0.039). However, between configurations, participants exhibited little change in other gait kinematics or kinetics, and no apparent or consistent difference in the rate of oxygen consumption (p = 0.097). None of the traditional biomechanical or metabolic outcomes seemed to explain user preference. However, an unexpected and intriguing observation was that all participants who wore the prosthesis on their dominant limb preferred the Flexible toe joint, and every other participant preferred the Locked configuration. Although perhaps coincidental, such findings may suggest a potential link between user preference and limb dominance, offering an interesting avenue for future research

Human Computation and Convergence

Humans are the most effective integrators and producers of information, directly and through the use of information-processing inventions. As these inventions become increasingly sophisticated, the substantive role of humans in processing information will tend toward capabilities that derive from our most complex cognitive processes, e.g., abstraction, creativity, and applied world knowledge. Through the advancement of human computation - methods that leverage the respective strengths of humans and machines in distributed information-processing systems - formerly discrete processes will combine synergistically into increasingly integrated and complex information processing systems. These new, collective systems will exhibit an unprecedented degree of predictive accuracy in modeling physical and techno-social processes, and may ultimately coalesce into a single unified predictive organism, with the capacity to address societies most wicked problems and achieve planetary homeostasis.Comment: Pre-publication draft of chapter. 24 pages, 3 figures; added references to page 1 and 3, and corrected typ

The Minimal Scale Invariant Extension of the Standard Model

We perform a systematic analysis of an extension of the Standard Model that includes a complex singlet scalar field and is scale invariant at the tree level. We call such a model the Minimal Scale Invariant extension of the Standard Model (MSISM). The tree-level scale invariance of the model is explicitly broken by quantum corrections, which can trigger electroweak symmetry breaking and potentially provide a mechanism for solving the gauge hierarchy problem. Even though the scale invariant Standard Model is not a realistic scenario, the addition of a complex singlet scalar field may result in a perturbative and phenomenologically viable theory. We present a complete classification of the flat directions which may occur in the classical scalar potential of the MSISM. After calculating the one-loop effective potential of the MSISM, we investigate a number of representative scenarios and determine their scalar boson mass spectra, as well as their perturbatively allowed parameter space compatible with electroweak precision data. We discuss the phenomenological implications of these scenarios, in particular, whether they realize explicit or spontaneous CP violation, neutrino masses or provide dark matter candidates. In particular, we find a new minimal scale-invariant model of maximal spontaneous CP violation which can stay perturbative up to Planck-mass energy scales, without introducing an unnaturally large hierarchy in the scalar-potential couplings.Comment: 71 pages, 34 eps figures, numerical error corrected, clarifying comments adde

Mesenchymal Stromal Cell secretome is affected by tissue source and donor age.

Variation in Mesenchymal Stromal Cell (MSC) function depending on their origin is problematic, as it may confound clinical outcomes of MSC therapy. Current evidence suggests that the therapeutic benefits of MSCs are attributed to secretion of biologically active factors (secretome). However, the effect of donor characteristics on the MSC secretome remains largely unknown. Here, we examined the influence of donor age, sex and tissue source, on the protein profile of the equine MSC secretome. We used dynamic metabolic labelling with stable isotopes combined with liquid chromatography-tandem mass spectrometry (LC-MS/MS) to identify secreted proteins in MSC conditioned media (CM). Seventy proteins were classified as classically-secreted based on the rate of label incorporation into newly synthesised proteins released into the extracellular space. Next, we analysed CM of bone marrow- (n = 14) and adipose-derived MSCs (n = 16) with label-free LC-MS/MS. Clustering analysis of 314 proteins detected across all samples identified tissue source as the main factor driving variability in MSC CM proteomes. Linear modelling applied to the subset of 70 secreted proteins identified tissue-related difference in the abundance of 23 proteins. There was an age-related decrease in the abundance of CTHRC1 and LOX, further validated with orthogonal techniques. Due to the lack of flow cytometry characterisation of MSC surface markers, the analysis could not account for the potential effect of cell population heterogeneity. This study provides evidence that tissue source and donor age contribute to differences in the protein composition of MSC secretomes which may influence the effects of MSC therapy

High-throughput UHPLC/MS/MS-based metabolic profiling using a vacuum jacketed column

In UHPLC, frictional heating from the eluent flowing through the column at pressures of ca. 10–15 Kpsi causes radial diffusion via temperature differences between the center of the column and its walls. Longitudinal dispersion also occurs due to temperature gradients between the inlet and outlet. These effects cause band broadening but can be mitigated via a combination of vacuum jacketed stainless steel tubing, reduced column end nut mass, and a constant temperature in the column from heating the inlet fitting. Here, vacuum jacketed column (VJC) technology, employing a novel column housing located on the source of the mass spectrometer and minimized tubing from the column outlet to the electrospray probe, was applied to profiling metabolites in urine. For a 75 s reversed-phase gradient separation, the average peak widths for endogenous compounds in urine were 1.2 and 0.6 s for conventional LC/MS and VJC systems, respectively. The peak tailing factor was reduced from 1.25 to 1.13 when using the VJC system compared to conventional UHPLC, and the peak capacity increased from 65 to 120, with a 25% increase in features detected in urine. The increased resolving power of the VJC system reduced co-elution, simplifying MS and MS/MS spectra, providing a more confident metabolite identification. The increased LC performance also gave more intense MS peaks, with a 10–120% increase in response, improving the quality of the MS data and detection limits. Reducing the LC gradient duration to 37 s gave peak widths of ca. 0.4 s and a peak capacity of 84

Diets of European polecat Mustela putorius in Great Britain during fifty years of population recovery

This is the final version. Available from Springer via the DOI in this record. Following nineteenth-century declines, polecats Mustela putorius are recolonising Great Britain. Polecat diet relates to two potential risks to recovery. First, rabbits Oryctolagus cuniculus, which are important prey for polecats, have experienced extreme population fluctuations, with near extirpation due to myxomatosis in the 1950s, recovery in 1960s–1990s and declines in 1990s–2010s. Second, polecats are secondarily exposed to anticoagulant rodenticides by eating contaminated rodents, and the frequency of polecat exposure to rodenticides is increasing. We analysed stomach contents from 99 polecats collected in 2012–2016 and compared results with earlier studies. Lagomorphs were the most abundant prey (66% frequency of occurrence, 95% confidence interval 53–74%), followed by other mammals (12%, 4–18%), amphibians (10%, 3–16%) and birds (7%, 1–13%). Diet varied seasonally; lagomorph occurrence was highest in spring and summer and lowest in autumn. Dietary niche breadth was greater in the 1960s, when rabbits were scarce, than in other decades, but did not differ between the 1990s and 2010s, indicating that diets have not diversified with recent rabbit declines. This may be because rabbit abundance is not yet low enough to cause dietary diversification or because polecats were collected in areas where rabbits were still abundant. Rodents did not increase in diet between the 1990s and 2010s and still occur with < 10% frequency, indicating that rodents need not contribute much to diet to expose polecats to rodenticides. This potentially limits the effectiveness of management actions designed to minimise polecat exposure to contaminated rodent prey.Vincent Wildlife TrustUniversity of Exete

Neutrino Mass and μ→e+γ\mu \rightarrow e + \gamma from a Mini-Seesaw

The recently proposed "mini-seesaw mechanism" combines naturally suppressed Dirac and Majorana masses to achieve light Standard Model neutrinos via a low-scale seesaw. A key feature of this approach is the presence of multiple light (order GeV) sterile-neutrinos that mix with the Standard Model. In this work we study the bounds on these light sterile-neutrinos from processes like \mu ---> e + \gamma, invisible Z-decays, and neutrinoless double beta-decay. We show that viable parameter space exists and that, interestingly, key observables can lie just below current experimental sensitivities. In particular, a motivated region of parameter space predicts a value of BR(\mu ---> e + \gamma) within the range to be probed by MEG.Comment: 1+26 pages, 7 figures. v2 JHEP version (typo's fixed, minor change to presentation, results unchanged