Stable high repetition-rate laser-driven proton beam production for multidisciplinary applications on the advanced laser light source ion beamline.

Laser-driven proton accelerators are relevant candidates for many applications such as material science or medicine. Today, there are multi-hundred-TW table-top laser systems that can generate relativistic peak intensities >1018 W/cm2 and routinely reach proton energies in the MeV range. However, for most desired applications, there is still a need to optimize the quality and stability of the laser-generated proton beam. In this work, we developed a 0.625 Hz high repetition-rate setup in which a laser with 2.5% RMS energy stability is irradiating a solid target with an intensity of 1019 to 1020 W/cm2 to explore proton energy and yield variations, both with high shot statistics (up to about 400 laser shots) and using different interaction targets. Investigating the above-mentioned parameters is important for applications that rely on specific parts of the proton spectrum or a high ion flux produced over quick multi-shot irradiation. We demonstrate that the use of a stable "multi-shot mode" allows improving applications, e.g., in the detection of trace elements using laser-driven particle-induced x-ray emission.

Complexity is complicated and so too is comparing complexity metrics-A response to Mikula et al. (2018).

In a recent publication (Pearse et al. 2018b), we explored the macroevolution and macroecology of passerine song using a large citizen science database of bird songs and powerful machine learning tools. Mikula et al. (2018) examine a small subset (<8%) of the data we used, and suggest that our metric of song complexity, the SD of frequency (SDF), does not correlate to other metrics of birdsong complexity, specifically syllable repertoire size and syllable diversity. We comment on the diversity of complexity metrics that exist in the field at present, and, while acknowledging that metrics may differ, outline how this variety allows us to ask more biologically nuanced questions. We see no reason or need for all complexity metrics to be correlated. Since different complexity metrics have been, and will continue to be, used, we outline how metrics could be fairly compared in the future.

Global macroevolution and macroecology of passerine song.

Studying the macroevolution of the songs of Passeriformes (perching birds) has proved challenging. The complexity of the task stems not just from the macroevolutionary and macroecological challenge of modeling so many species, but also from the difficulty in collecting and quantifying birdsong itself. Using machine learning techniques, we extracted songs from a large citizen science dataset, and then analyzed the evolution, and biotic and abiotic predictors of variation in birdsong across 578 passerine species. Contrary to expectations, we found few links between life-history traits (monogamy and sexual dimorphism) and the evolution of song pitch (peak frequency) or song complexity (standard deviation of frequency). However, we found significant support for morphological constraints on birdsong, as reflected in a negative correlation between bird size and song pitch. We also found that broad-scale biogeographical and climate factors such as net primary productivity, temperature, and regional species richness were significantly associated with both the evolution and present-day distribution of bird song features. Our analysis integrates comparative and spatial modeling with newly developed data cleaning and curation tools, and suggests that evolutionary history, morphology, and present-day ecological processes shape the distribution of song diversity in these charismatic and important birds.

Effects of Muscle Fatigue, Creep, and Musculoskeletal Pain on Neuromuscular Responses to Unexpected Perturbation of the Trunk: A Systematic Review.

Introduction: Trunk neuromuscular responses have been shown to adapt under the influence of muscle fatigue, as well as spinal tissue creep or even with the presence of low back pain (LBP). Despite a large number of studies exploring how these external perturbations affect the spinal stability, characteristics of such adaptations remains unclear. Aim: The purpose of this systematic review was to assess the quality of evidence of studies investigating trunk neuromuscular responses to unexpected trunk perturbation. More specifically, the targeted neuromuscular responses were trunk muscle activity reflex and trunk kinematics under the influence of muscle fatigue, spinal creep, and musculoskeletal pain. Methods: A research of the literature was conducted in Pubmed, Embase, and Sport-Discus databases using terms related to trunk neuromuscular reflex responses, measured by electromyography (baseline activity, reflex latency, and reflex amplitude) and/or trunk kinematic, in context of unexpected external perturbation. Moreover, independent variables must be either trunk muscle fatigue or spinal tissue creep or LBP. All included articles were scored for their electromyography methodology based on the "Surface Electromyography for the Non-Invasive Assessment of Muscles (SENIAM)" and the "International Society of Electrophysiology and Kinesiology (ISEK)" recommendations whereas overall quality of articles was scored using a specific quality checklist modified from the Quality Index. Meta-analysis was performed on reflex latency variable. Results: A final set of 29 articles underwent quality assessments. The mean quality score was 79%. No effect of muscle fatigue on erector spinae reflex latency following an unexpected perturbation, nor any other distinctive effects was found for back muscle fatigue and reflex parameters. As for spinal tissue creep effects, no alteration was found for any of the trunk reflex variables. Finally, the meta-analysis revealed an increased erector spinae reflex latency in patients with chronic LBP in comparison with healthy controls following an unexpected trunk perturbation. Conclusion: The literature provides some evidence with regard to trunk adaptions in a context of spinal instability. However, most of the evidence was inconclusive due to a high methodological heterogeneity between the studies.

On the evolution of dispersal via heterogeneity in spatial connectivity.

Dispersal has long been recognized as a mechanism that shapes many observed ecological and evolutionary processes. Thus, understanding the factors that promote its evolution remains a major goal in evolutionary ecology. Landscape connectivity may mediate the trade-off between the forces in favour of dispersal propensity (e.g. kin-competition, local extinction probability) and those against it (e.g. energetic or survival costs of dispersal). It remains, however, an open question how differing degrees of landscape connectivity may select for different dispersal strategies. We implemented an individual-based model to study the evolution of dispersal on landscapes that differed in the variance of connectivity across patches ranging from networks with all patches equally connected to highly heterogeneous networks. The parthenogenetic individuals dispersed based on a flexible logistic function of local abundance. Our results suggest, all else being equal, that landscapes differing in their connectivity patterns will select for different dispersal strategies and that these strategies confer a long-term fitness advantage to individuals at the regional scale. The strength of the selection will, however, vary across network types, being stronger on heterogeneous landscapes compared with the ones where all patches have equal connectivity. Our findings highlight how landscape connectivity can determine the evolution of dispersal strategies, which in turn affects how we think about important ecological dynamics such as metapopulation persistence and range expansion.

Can wide consultation help with setting priorities for large-scale biodiversity monitoring programs?

Climate and other global change phenomena affecting biodiversity require monitoring to track ecosystem changes and guide policy and management actions. Designing a biodiversity monitoring program is a difficult task that requires making decisions that often lack consensus due to budgetary constrains. As monitoring programs require long-term investment, they also require strong and continuing support from all interested parties. As such, stakeholder consultation is key to identify priorities and make sound design decisions that have as much support as possible. Here, we present the results of a consultation conducted to serve as an aid for designing a large-scale biodiversity monitoring program for the province of Québec (Canada). The consultation took the form of a survey with 13 discrete choices involving tradeoffs in respect to design priorities and 10 demographic questions (e.g., age, profession). The survey was sent to thousands of individuals having expected interests and knowledge about biodiversity and was completed by 621 participants. Overall, consensuses were few and it appeared difficult to create a design fulfilling the priorities of the majority. Most participants wanted 1) a monitoring design covering the entire territory and focusing on natural habitats; 2) a focus on species related to ecosystem services, on threatened and on invasive species. The only demographic characteristic that was related to the type of prioritization was the declared level of knowledge in biodiversity (null to high), but even then the influence was quite small.

Effects of short-term normobaric hypoxia on haematology, muscle phenotypes and physical performance in highly trained athletes.

This study aimed to determine the impact of short-term normobaric hypoxia on physiology and performance in highly trained athletes. Twelve (7 male and 5 female) athletes were randomly assigned into two groups and spent 8 h per night for two consecutive nights a week over 3 weeks under either short-term normobaric hypoxia (simulating 3636 m altitude, inspired O2=13%) or in normobaric normoxia in a single-blind study. Following a 3 week washout period, athletes were then exposed to the other condition. Athletes were tested for maximal oxygen consumption and time to exhaustion on an electromagnetically braked cycle ergometer before and after each treatment in addition to being tested for anaerobic performance (Wingate test) on a modified Monark cycle ergometer. Blood samples were taken throughout the experiment and vastus lateralis muscle biopsies were taken before and after each treatment. Increases in red blood cell count, haematocrit, haemoglobin, platelet number and erythropoietin concentration were observed following short-term normobaric hypoxia. Except for a modest decrease in phosphofructokinase activity following short-term normobaric hypoxia, no changes were observed in muscle enzyme activities, buffer capacity, capillary density or morphology. No performance measures were changed following short-term normobaric hypoxia or normobaric normoxia. Although short-term normobaric hypoxia exposure increased levels of a number of haematological parameters, this was not associated with improved aerobic or anaerobic performance in highly trained athletes.