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Aims Treatment of patients with heart failure (HF) relies on measurement of LVEF. However, the extent to which EF is recorded varies markedly. We sought to characterize the patient group that is missing a measure of EF, and to explore the association between missing EF and outcome. Methods and results Individual data on 30 445 patients from 28 observational studies in the Meta-Analysis Global Group in Chronic Heart Failure (MAGGIC) project were used to compare the prevalence of co-morbidities and outcome across three groups of HF patients: those with missing EF (HF-mEF), reduced EF (HF-REF), and preserved EF (HF-PEF). A total of 29% had HF-mEF, 52% HF-REF, and 19% HF-PEF. Compared with patients in whom EF was known, patients with HF-mEF were older, had a greater prevalence of COPD and previous stroke, and were smokers. Patients with HF-mEF were less likely to receive evidence-based treatment than those with HF-REF. Adjusted mortality in HF-mEF was similar to that in HF-REF and greater than that in HF-PEF at 3 years [HF-REF, hazard ratio (HR) 1.03, 95% confidence interval (CI) 0.95–1.12); HF-PEF, HR 0.78, 95% CI 0.71–0.86]. Conclusion Missing EF is common. The short- and long-term outcome of patients with HF-mEF is poor and they exhibit different co-morbidity profiles and treatment patterns compared with patients with known EF. HF patients with missing EF represent a high risk group.

In this paper, we present a joint channel estimation and synchronization technique for burst-mode OFDM systems. The technique uses the nonlinear recursive least squares algorithm (NL-RLS) to jointly estimate the channel impulse response (CIR), the carrier frequency offset (CFO), the sampling clock offset (SCO), and the timing offset, and to correct for each of these in the digital domain and without the use of a delay-locked loop (DLL). The need for pilot symbols in the payload data is eliminated by a decision-directed operation mode. The time-domain NL-RLS algorithm needs a small number of parameters to be estimated and can suppress the effect of decision feedback errors. Simulation results confirm its improved performance and relatively low variance.

Thank you for the opportunity to respond to the letter submitted by Gayda and colleagues in response to our recent review published in The Journal of Physiology (Gibala et al. 2012). With regards to their first comment regarding our new ‘practical’ high-intensity interval exercise (HIIE) protocol, we disagree with the assertion that ‘exercise intensity at 60% of peak power cannot be considered high intensity.’ In our efforts to develop a low-volume HIIE protocol that can be applied across different cohorts including clinical populations, we devised a model comprising 10 × 60 s work bouts at an intensity eliciting ∼85–90% of maximal heart rate (HRmax; averaged over the 10 intervals), interspersed by 60 s of recovery. We have found that the percentage of peak power output (PPO; determined using a standard ramp test to volitional fatigue which does not always elicit peak O2 uptake) that approximates the desired target heart rate (i.e. the % of HRmax) varies considerably between subjects and is exercise-mode specific. For example, in the study by Hood et al. (2011) which was conducted on sedentary healthy adults, a workload equivalent to 60% of PPO during upright cycling was sufficient to elicit a training intensity of ∼90% HRmax. However, in our recent study conducted on patients with type 2 diabetes, the intensity required to elicit ∼90% HRmax was ∼95% of PPO determined during recumbent cycling (Little et al. 2011). We agree with the assertion by Gayda and colleagues that ‘acute physiological responses during different HIIE protocols as well as patient's safety, tolerance and comfort should be tested before their implementation into training programs’. Ongoing protocol optimization work in our laboratory reveal that when interval exercise was prescribed as 80% of PPO in coronary artery disease (CAD) patients – most of whom were taking beta-blocker medication – the 10 × 60 s protocol resulted in peak heart rates during the exercise that averaged ∼85% of age-predicted HRmax. Further, the 10 × 60 s protocol was best tolerated and rated as most preferred by CAD patients in comparison with a modified Wingate protocol (repeated 30 s efforts at 100% PPO with 4 min unloaded cycling for recovery), the standard aerobic interval training protocol used by Wisloff and colleagues (2007), or a moderate-intensity continuous exercise (MICE) protocol. It is likely that high-intensity interval training (HIT) does not conform to a ‘one size fits all’ approach and the interval training stimulus needs to be tailored to individuals depending on their initial level of fitness, exercise tolerance, use of prescription medications and other factors. We also concur with the other main comment by Gayda and colleagues that ‘the superiority of this HIIE protocol [our 10 × 60 s ‘hard’/60 s ‘easy’ model]… needs to be demonstrated.’ Indeed, our review concluded ‘One aspect that is unclear from the present literature is the precise intensity and minimal volume of training that is needed to potentiate the effect of the stimulus-adaptation on outcomes such as mitochondrial biogenesis and relevant health markers. To answer such questions, a complex series of studies needs to be undertaken that systematically ‘titrate’ levels of the ‘training impulse’ and determine subsequent cellular, performance and clinical responses after divergent training interventions.’ Specifically with respect to the use of HIIE in patients with cardiovascular risk or cardiovascular disease, the letter by Gayda and colleagues highlights four references from their laboratory that were not cited in our review. Given the relatively broad scope of our review and the fact that Journal guidelines restricted the number of references to 50, it was obviously not possible to cite all relevant work. Moreover, two of the citations listed by Gayda et al. were acute exercise studies (whereas the focus of our review was training adaptations) and the other two citations were a journal abstract and a recent paper published in February 2012 (neither of which we had access to at the time of submission of our original manuscript). We are also aware of the pioneering research conducted by Meyer and colleagues (e.g. Meyer et al. 1998) and have acknowledged this work in a previous commentary (MacDonald & Currie, 2009). We apologize to all authors whose work on interval training we could not cite due to the broad focus of our review and referencing limitations imposed by The Journal.

The Neotropical species of the rarely collected genus Bolitogyrus (Coleoptera: Staphylinidae: Staphylininae: Staphylinini) are revised. The genus exhibits an uncommon, disjunct distribution between the Neotropical and Oriental Regions and is of unknown phylogenetic position within Staphylinini. Morphological evolution remarkable for Staphylinini was discovered within Bolitogyrus, including sexually dimorphic modifications of the pronotum that may be involved in male competition for females. rSEM interactive animations were used to establish morphological species boundaries between two highly variable species and are provided to illustrate diagnostic characters of the genitalia in unconventional views. The genus is redescribed based on the world fauna and twenty-eight Neotropical species are considered valid. Of these, nineteen are described as new to science: Bolitogyrus ashei sp. n.; B. apicofasciatus sp. n.; B. brevistellus sp. n.; B. bufo sp. n.; B. cheungi sp. n.; B. cornutus sp. n.; B. divisus sp. n.; B. falini sp. n.; B. gracilis sp. n.; B. inexspectatus sp. n.; B. longistellus sp. n.; B. marquezi sp. n.; B. newtoni sp. n.; B. pseudotortifolius sp. n.; B. pulchrus sp. n.; B. silex sp. n.; B. thomasi sp. n.; B. tortifolius sp. n.; and B. viridescens sp. n. Bolitogyrus sallei (Kraatz), stat. r. is removed from synonymy with B. buphthalmus (Erichson) and the following new synonyms are proposed: Cyrtothorax cyanescens Sharp, 1884, syn. n. = Quedius buphthalmus Erichson, 1840; C. nevermanni Scheerpeltz, 1974, syn. n. = C. costaricensis Wendeler, 1927. A summary of all available bionomic and distributional data, as well as an illustrated identification key to and diagnoses of all Neotropical species are provided.

Seventy six senior academics from 11 countries invite The BMJ ’s editors to reconsider their policy of rejecting qualitative research on the grounds of low priority. They challenge the journal to develop a proactive, scholarly, and pluralist approach to research that aligns with its stated mission

Argininosuccinate synthetase catalyzes the transformation of citrulline and aspartate into argininosuccinate and pyrophos­phate using the hydrolysis of ATP to AMP and pyrophos­phate. This enzymatic process constitutes the rate-limiting step in both the urea and arginine–citrulline cycles. Previous studies have investigated the crystal structures of argininosuccinate synthetase from bacterial species. In this work, the first crystal structure of human argininosuccinate synthetase in complex with the substrates citrulline and aspartate is presented. The human enzyme is compared with structures of argininosuccinate synthetase from bacteria. In addition, the structure also provides new insights into the function of the numerous clinical mutations identified in patients with type I citrullinaemia (also known as classic citrullinaemia).

Key points Ketone bodies are proposed to represent an alternative fuel source driving energy production, particularly during exercise. Biologically, the extent to which mitochondria utilize ketone bodies compared to other substrates remains unknown. We demonstratein vitrothat maximal mitochondrial respiration supported by ketone bodies is low when compared to carbohydrate-derived substrates in the left ventricle and red gastrocnemius muscle from rodents, and in human skeletal muscle. When considering intramuscular concentrations of ketone bodies and the presence of other carbohydrate and lipid substrates, biological rates of mitochondrial respiration supported by ketone bodies are predicted to be minimal. At the mitochondrial level, it is therefore unlikely that ketone bodies are an important source for energy production in cardiac and skeletal muscle, particularly when other substrates are readily available. Ketone bodies (KB) have recently gained popularity as an alternative fuel source to support mitochondrial oxidative phosphorylation and enhance exercise performance. However, given the low activity of ketolytic enzymes and potential inhibition from carbohydrate oxidation, it remains unknown if KBs can contribute to energy production. We therefore determined the ability of KBs (sodiumdl-beta-hydroxybutyrate, beta-HB; lithium acetoacetate, AcAc) to stimulatein vitromitochondrial respiration in the left ventricle (LV) and red gastrocnemius (RG) of rats, and in human vastus lateralis. Compared to pyruvate, the ability of KBs to maximally drive respiration was low in isolated mitochondria and permeabilized fibres (PmFb) from the LV (similar to 30-35% of pyruvate), RG (similar to 10-30%), and human vastus lateralis (similar to 2-10%). In PmFb, the concentration of KBs required to half-maximally drive respiration (LV: 889 mu m beta-HB, 801 mu mAcAc; RG: 782 mu m beta-HB, 267 mu mAcAc) were greater than KB content representative of the muscle microenvironment (similar to 100 mu m). This would predict low rates (similar to 1-4% of pyruvate) of biological KB-supported respiration in the LV (8-14 pmol s(-1) mg(-1)) and RG (3-6 pmol s(-1) mg(-1)) at rest and following exercise. Moreover, KBs did not increase respiration in the presence of saturating pyruvate, submaximal pyruvate (100 mu m) reduced the ability of physiological beta-HB to drive respiration, and addition of other intracellular substrates (succinate + palmitoylcarnitine) decreased maximal KB-supported respiration. As a result, product inhibition is likely to limit KB oxidation. Altogether, the ability of KBs to drive mitochondrial respiration is minimal and they are likely to be outcompeted by other substrates, compromising their use as an important energy source.

Background: We wished to compare the nuisance parameters of pediatric vs. adult randomized-trials (RCTs) and determine if the latter can be used in sample size computations of the former.Methods: In this meta-epidemiologic empirical evaluation we examined meta-analyses from the Cochrane Database of Systematic-Reviews, with at least one pediatric-RCT and at least one adult-RCT. Within each meta-analysis of binary efficacy-outcomes, we calculated the pooled-control-group event-rate (CER) across separately all pediatric and adult-trials, using random-effect models and subsequently calculated the control-group event-rate risk-ratio (CER-RR) of the pooled-pediatric-CERs vs. adult-CERs. Within each meta-analysis with continuous outcomes we calculated the pooled-control-group effect standard deviation (CE-SD) across separately all pediatric and adult-trials and subsequently calculated the CE-SD-ratio of the pooled-pediatric-CE-SDs vs. adult-CE-SDs. We then calculated across all meta-analyses the pooled-CER-RRs and pooled-CE-SD-ratios (primary endpoints) and the pooled-magnitude of effect-sizes of CER-RRs and CE-SD-ratios using REMs. A ratio < 1 indicates that pediatric trials have smaller nuisance parameters than adult trials.Results: We analyzed 208 meta-analyses (135 for binary-outcomes, 73 for continuous-outcomes). For binary outcomes, pediatric-RCTs had on average 10% smaller CERs than adult-RCTs (summary-CE-RR: 0.90; 95% CI: 0.83, 0.98). For mortality outcomes the summary-CE-RR was 0.48 (95% CIs: 0.31, 0.74). For continuous outcomes, pediatric-RCTs had on average 26% smaller CE-SDs than adult-RCTs (summary-CE-SD-ratio: 0.74).Conclusions: Clinically relevant differences in nuisance parameters between pediatric and adult trials were detected. These differences have implications for design of future studies. Extrapolation of nuisance parameters for sample-sizes calculations from adult-trials to pediatric-trials should be cautiously done.

The authors also acknowledge the support and collaboration of many other colleagues in their respective institutes, research communities and IT Infrastructures, together with the funding received by these from many different sources. These include but are not limited to the following: (i) The Worldwide LHC Computing Grid (WLCG) project is a global collaboration of more than 170 computing centres in 43 countries, linking up national and international grid infrastructures. Funding is acknowledged from many national funding bodies and we acknowledge the support of several operational infrastructures including EGI, OSG and NDGF/NeIC. (ii) EGI acknowledges the funding and support received from the European Commission and the many National Grid Initiatives and other members. EOSC-hub receives funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 777536. (iii) The work leading to these results has received funding from the European Union's Horizon 2020 research and innovation programme under Grant Agreement No. 730941 (AARC2). (iv) Work on the development of ESGF's identity management system has been supported by The UK Natural Environment Research Council and funding from the European Union's Seventh Framework Programme for research, technological development and demonstration through projects IS-ENES (grant agreement no 228203) and IS-ENES2 (grant agreement no 312979). (v) Ludek Matyska and Michal Prochazka acknowledge funding from the RI ELIXIR CZ project funded by MEYS Czech Republic No. LM2015047. (vi) Scott Koranda acknowledges support provided by the United States National Science Foundation under Grant No. PHY-1700765. (vii) GÉANT Association on behalf of the GN4 Phase 2 project (GN4-2).The research leading to these results has received funding from the European Union's Horizon 2020 research and innovation programme under Grant Agreement No. 731122(GN4-2). (viii) ELIXIR acknowledges support from Research Infrastructure programme of Horizon 2020 grant No 676559 EXCELERATE. (ix) CORBEL life science cluster acknowledges support from Horizon 2020 research and innovation programme under grant agreement No 654248. (x) Mirjam van Daalen acknowledges that the research leading to this result has been supported by the project CALIPSOplus under the Grant Agreement 730872 from the EU Framework Programme for Research and Innovation HORIZON 2020. (xi) EISCAT is an international association supported by research organisations in China (CRIRP), Finland (SA), Japan (NIPR), Norway (NFR), Sweden (VR), and the United Kingdom (NERC). This white-paper expresses common requirements of Research Communities seeking to leverage Identity Federation for Authentication and Authorisation. Recommendations are made to Stakeholders to guide the future evolution of Federated Identity Management in a direction that better satisfies research use cases. The authors represent research communities, Research Services, Infrastructures, Identity Federations and Interfederations, with a joint motivation to ease collaboration for distributed researchers. The content has been edited collaboratively by the Federated Identity Management for Research (FIM4R) Community, with input sought at conferences and meetings in Europe, Asia and North America.

The capacity to focus one's attention for an extended period of time can be increased through training in contemplative practices. However, the cognitive processes engaged during meditation that support trait changes in cognition are not well characterized. We conducted a longitudinal wait-list controlled study of intensive meditation training. Retreat participants practiced focused attention (FA) meditation techniques for three months during an initial retreat. Wait-list participants later undertook formally identical training during a second retreat. Dense-array scalp-recorded electroencephalogram (EEG) data were collected during 6 min of mindfulness of breathing meditation at three assessment points during each retreat. Second-order blind source separation, along with a novel semi-automatic artifact removal tool (SMART), was used for data preprocessing. We observed replicable reductions in meditative state-related beta-band power bilaterally over anteriocentral and posterior scalp regions. In addition, individual alpha frequency (IAF) decreased across both retreats and in direct relation to the amount of meditative practice. These findings provide evidence for replicable longitudinal changes in brain oscillatory activity during meditation and increase our understanding of the cortical processes engaged during meditation that may support long-term improvements in cognition.