Niche conservatism and ecological change during the Late Devonian mass extinction.

Studies of the fossil record can inform our understanding of not only the causes of mass extinctions, but also their effects on biodiversity, ecology and evolution. Here, we examine regional-scale ecological changes resulting from a Late Devonian mass extinction event using brachiopod fossil assemblages from the Appalachian Basin. About half of the species went extinct, but were largely replaced by new immigrant taxa. Both before and after the extinction, the primary gradient in faunal composition was correlated with onshore-offshore position, with a second gradient attributed to frequency of disturbance. Survivors of the extinction displayed a strong degree of niche conservatism along these gradients. Despite these indicators of ecological stability, the pre- and post-extinction faunas were quite distinct at the order level, with atrypids and strophomenids largely replaced by productids, whose spiny shells may have provided greater resistance to disturbance and/or predation. Thus, extinction survivors persisted in similar ecological niches despite environmental perturbations and considerable change in the taxonomic and ecological composition of the regional species pool.

Dynamics of Nanosecond Laser Pulse Propagation and of Associated Instabilities in a Magnetized Underdense Plasma.

The propagation and energy coupling of intense laser beams in plasmas are critical issues in inertial confinement fusion. Applying magnetic fields to such a setup has been shown to enhance fuel confinement and heating. Here we report on experimental measurements demonstrating improved transmission and increased smoothing of a high-power laser beam propagating in a magnetized underdense plasma. We also measure enhanced backscattering, which our kinetic simulations show is due to magnetic confinement of hot electrons, thus leading to reduced target preheating.

Change of carrier density at the pseudogap critical point of a cuprate superconductor.

The pseudogap is a partial gap in the electronic density of states that opens in the normal (non-superconducting) state of cuprate superconductors and whose origin is a long-standing puzzle. Its connection to the Mott insulator phase at low doping (hole concentration, p) remains ambiguous and its relation to the charge order that reconstructs the Fermi surface at intermediate doping is still unclear. Here we use measurements of the Hall coefficient in magnetic fields up to 88 tesla to show that Fermi-surface reconstruction by charge order in the cuprate YBa2Cu3Oy ends sharply at a critical doping p = 0.16 that is distinctly lower than the pseudogap critical point p* = 0.19 (ref. 11). This shows that the pseudogap and charge order are separate phenomena. We find that the change in carrier density n from n = 1 + p in the conventional metal at high doping (ref. 12) to n = p at low doping (ref. 13) starts at the pseudogap critical point. This shows that the pseudogap and the antiferromagnetic Mott insulator are linked.

Laser-Produced Magnetic-Rayleigh-Taylor Unstable Plasma Slabs in a 20 T Magnetic Field.

Magnetized laser-produced plasmas are central to many novel laboratory astrophysics and inertial confinement fusion studies, as well as in industrial applications. Here we provide the first complete description of the three-dimensional dynamics of a laser-driven plasma plume expanding in a 20 T transverse magnetic field. The plasma is collimated by the magnetic field into a slender, rapidly elongating slab, whose plasma-vacuum interface is unstable to the growth of the "classical," fluidlike magnetized Rayleigh-Taylor instability.

Construct and criterion validity testing of the Non-Technical Skills for Surgeons (NOTSS) behaviour assessment tool using videos of simulated operations.

BACKGROUND: Surgeons' non-technical skills are an important part of surgical performance and surgical education. The most widely adopted assessment tool is the Non-Technical Skills for Surgeons (NOTSS) behaviour rating system. Psychometric analysis of this tool to date has focused on inter-rater reliability and feasibility rather than validation. METHODS: NOTSS assessments were collected from two groups of consultant/attending surgeons in the UK and USA, who rated behaviours of the lead surgeon during a video-based simulated crisis scenario after either online or classroom instruction. The process of validation consisted of assessing construct validity, scale reliability and concurrent criterion validity, and undertaking a sensitivity analysis. Central to this was confirmatory factor analysis to evaluate the structure of the NOTSS taxonomy. RESULTS: Some 255 consultant surgeons participated in the study. The four-category NOTSS model was found to have robust construct validity evidence, and a superior fit compared with alternative models. Logistic regression and sensitivity analysis revealed that, after adjusting for technical skills, for every 1-point increase in NOTSS score of the lead surgeon, the odds of having a higher versus lower patient safety score was 2·29 times. The same pattern of results was obtained for a broad mix of surgical specialties (UK) as well as a single discipline (cardiothoracic, USA). CONCLUSION: The NOTSS tool can be applied in research and education settings to measure non-technical skills in a valid and efficient manner.

Enhancement of Quasistationary Shocks and Heating via Temporal Staging in a Magnetized Laser-Plasma Jet.

We investigate the formation of a laser-produced magnetized jet under conditions of a varying mass ejection rate and a varying divergence of the ejected plasma flow. This is done by irradiating a solid target placed in a 20 T magnetic field with, first, a collinear precursor laser pulse (10^{12} W/cm^{2}) and, then, a main pulse (10^{13} W/cm^{2}) arriving 9-19 ns later. Varying the time delay between the two pulses is found to control the divergence of the expanding plasma, which is shown to increase the strength of and heating in the conical shock that is responsible for jet collimation. These results show that plasma collimation due to shocks against a strong magnetic field can lead to stable, astrophysically relevant jets that are sustained over time scales 100 times the laser pulse duration (i.e., >70 ns), even in the case of strong variability at the source.

A Three Month Home Exercise Programme Augmented with Nordic Poles for Patients with Intermittent Claudication Enhances Quality of Life and Continues to Improve Walking Distance and Compliance After One Year.

OBJECTIVE/BACKGROUND: The objective of this study was to collect 1 year follow-up information on walking distance, speed, compliance, and cost in patients with intermittent claudication who took part in a previously reported 12 week randomised clinical trial of a home exercise programme augmented with Nordic pole walking versus controls who walked normally. A second objective was to look at quality of life and ankle brachial pressure indices (ABPIs) after a 12 week augmented home exercise programme. METHODS: Thirty-two of the 38 patients who completed the original trial were followed-up after 6 and 12 months. Frequency, duration, speed, and distance of walking were recorded using diaries and pedometers. A new observational cohort of 29 patients was recruited to the same augmented home exercise programme. ABPIs, walking improvement, and quality of life questionnaire were recorded at baseline and 12 weeks (end of the programme). RESULTS: Both groups in the follow-up study continued to improve their walking distance and speed over the following year. Compliance was excellent: 98% of the augmented group were still walking with poles at both 6 and 12 months, while 74% of the control group were still walking at the same point. The augmented group increased their mean walking distance to 17.5 km by 12 months, with a mean speed of 4.2 km/hour. The control group only increased their mean walking distance from 4.2 km to 5.6 km, and speed to 3.3 km/hour. Repeated ANOVA showed the results to be highly significant (p = .002). The 21/29 patients who completed the observational study showed a statistically significant increase in resting ABPIs from baseline (mean ± SD 0.75 ± 0.12) to week 12 (mean ± SD 0.85 ± 0.12) (t = (20) -8.89, p = .000 [two-tailed]). All their walking improvement and quality of life parameters improved significantly (p = .002 or less in the six categories) over the same period and their mean health scores improved by 79%. CONCLUSIONS: Following a 12 week augmented home exercise programme, most patients with intermittent claudication continued to significantly improve their walking distance and walking speed at 1 year compared with normal walking. Quality of life and ABPIs improved significantly after only 12 weeks and it is postulated that the improvement in ABPI was due to collateral development. These results justify the belief that an augmented home exercise programme will be as clinically effective as existing supervised exercise programmes, with the added benefits of lower cost and better compliance. Funding for a multicentre trial comparing an augmented home exercise programme with existing supervised exercise programme is now urgently required.

Developmental aspects of a life course approach to healthy ageing.

We examine the mechanistic basis and wider implications of adopting a developmental perspective on human ageing. Previous models of ageing have concentrated on its genetic basis, or the detrimental effects of accumulated damage, but also have raised issues about whether ageing can be viewed as adaptive itself, or is a consequence of other adaptive processes, for example if maintenance and repair processes in the period up to reproduction are traded off against later decline in function. A life course model places ageing in the context of the attainment of peak capacity for a body system, starting in early development when plasticity permits changes in structure and function induced by a range of environmental stimuli, followed by a period of decline, the rate of which depends on the peak attained as well as the later life conditions. Such path dependency in the rate of ageing may offer new insights into its modification. Focusing on musculoskeletal and cardiovascular function, we discuss this model and the possible underlying mechanisms, including endothelial function, oxidative stress, stem cells and nutritional factors such as vitamin D status. Epigenetic changes induced during developmental plasticity, and immune function may provide a common mechanistic process underlying a life course model of ageing. The life course trajectory differs in high and low resource settings. New insights into the developmental components of the life course model of ageing may lead to the design of biomarkers of later chronic disease risk and to new interventions to promote healthy ageing, with important implications for public health.

Puddle-Induced Resistance Oscillations in the Breakdown of the Graphene Quantum Hall Effect.

We report on the stability of the quantum Hall plateau in wide Hall bars made from a chemically gated graphene film grown on SiC. The ν=2 quantized plateau appears from fields B≃5 T and persists up to B≃80 T. At high current density, in the breakdown regime, the longitudinal resistance oscillates with a 1/B periodicity and an anomalous phase, which we relate to the presence of additional electron reservoirs. The high field experimental data suggest that these reservoirs induce a continuous increase of the carrier density up to the highest available magnetic field, thus enlarging the quantum plateaus. These in-plane inhomogeneities, in the form of high carrier density graphene pockets, modulate the quantum Hall effect breakdown and decrease the breakdown current.

The quality and diagnostic value of open narratives in verbal autopsy: a mixed-methods analysis of partnered interviews from Malawi.

BACKGROUND: Verbal autopsy (VA), the process of interviewing a deceased's family or caregiver about signs and symptoms leading up to death, employs tools that ask a series of closed questions and can include an open narrative where respondents give an unprompted account of events preceding death. The extent to which an individual interviewer, who generally does not interpret the data, affects the quality of this data, and therefore the assigned cause of death, is poorly documented. We aimed to examine inter-interviewer reliability of open narrative and closed question data gathered during VA interviews. METHODS: During the introduction of VA data collection, as part of a larger study in Mchinji district, Malawi, we conducted partner interviews whereby two interviewers independently recorded open narrative and closed questions during the same interview. Closed questions were collected using a smartphone application (mobile-InterVA) and open narratives using pen and paper. We used mixed methods of analysis to evaluate the differences between recorded responses to open narratives and closed questions, causes of death assigned, and additional information gathered by open narrative. RESULTS: Eighteen partner interviews were conducted, with complete data for 11 pairs. Comparing closed questions between interviewers, the median number of differences was 1 (IQR: 0.5-3.5) of an average 65 answered; mean inter-interviewer concordance was 92% (IQR: 92-99%). Discrepancies in open narratives were summarized in five categories: demographics, history and care-seeking, diagnoses and symptoms, treatment and cultural. Most discrepancies were seen in the reporting of diagnoses and symptoms (e.g., malaria diagnosis); only one pair demonstrated no clear differences. The average number of clinical symptoms reported was 9 in open narratives and 20 in the closed questions. Open narratives contained additional information on health seeking and social issues surrounding deaths, which closed questions did not gather. CONCLUSIONS: The information gleaned during open narratives was subject to inter-interviewer variability and contained a limited number of symptom indicators, suggesting that their use for assigning cause of death is questionable. However, they contained rich information on care-seeking, healthcare provision and social factors in the lead-up to death, which may be a valuable source of information for promoting accountable health services.

Predicted shortage of vascular surgeons in the United Kingdom: A matter for debate?

BACKGROUND: Vascular surgery became a new independent surgical specialty in the United Kingdom (UK) in 2013. In this matter for debate we discuss the question, is there a "shortage of vascular surgeons in the United Kingdom?" MATERIALS AND METHODS: We used data derived from the "Vascular Surgery United Kingdom Workforce Survey 2014", NHS Employers Electronic Staff Records (ESR), and the National Vascular Registry (NVR) surgeon-level public report to estimate current and predict future workforce requirements. RESULTS: We estimate there are approximately 458 Consultant Vascular Surgeons for the current UK population of 63 million, or 1 per 137,000 population. In several UK Regions there are a large number of relatively small teams (3 or less) of vascular surgeons working in separate NHS Trusts in close geographical proximity. In developed countries, both the number and complexity of vascular surgery procedures (open and endovascular) per capita population is increasing, and concerns have been raised that demand cannot be met without a significant expansion in numbers of vascular surgeons. Additional workforce demand arises from the impact of population growth and changes in surgical work-patterns with respect to gender, working-life-balance and 7-day services. CONCLUSIONS: We predict a future shortage of Consultant Vascular Surgeons in the UK and recommend an increase in training numbers and an expansion in the UK Consultant Vascular Surgeon workforce to accommodate population growth, facilitate changes in work-patterns and to create safe sustainable services.

A simple intervention to improve antibiotic treatment times for neutropenic sepsis.

OBJECTIVES: Patients with suspected Neutropenic sepsis require rapid antibiotic administration, but despite extensive education, only 67% of patients received antibiotics within 60 minutes . METHODS: A Neutropenic Sepsis Alert Card was created, as a Patient Specific Directive - this allows nurses to administer antibiotics to specific patients without prior medical review. RESULTS: Since the intervention, 301 patients presented with suspected neutropenic sepsis. 277 patients (92%) received their first dose of intravenous antibiotics within 1 hour of arrival into hospital, compared to 95 out of 143 patients (67%) presenting between January and June of 2014 (p=0.036). CONCLUSION: The Neutropenic Sepsis Alert Card can significantly improve door to antibiotic needle time for chemotherapy patients with suspected neutropenic sepsis. This intervention is inexpensive and easily replicable in other health care organisations.

Dichotomy between the Hole and Electron Behavior in Multiband Superconductor FeSe Probed by Ultrahigh Magnetic Fields.

Magnetoresistivity ρ(xx) and Hall resistivity ρ(xy) in ultrahigh magnetic fields up to 88 T are measured down to 0.15 K to clarify the multiband electronic structure in high-quality single crystals of superconducting FeSe. At low temperatures and high fields we observe quantum oscillations in both resistivity and the Hall effect, confirming the multiband Fermi surface with small volumes. We propose a novel approach to identify from magnetotransport measurements the sign of the charge carriers corresponding to a particular cyclotron orbit in a compensated metal. The observed significant differences in the relative amplitudes of the quantum oscillations between the ρ(xx) and ρ(xy) components, together with the positive sign of the high-field ρ(xy), reveal that the largest pocket should correspond to the hole band. The low-field magnetotransport data in the normal state suggest that, in addition to one hole and one almost compensated electron band, the orthorhombic phase of FeSe exhibits an additional tiny electron pocket with a high mobility.

The vascular surgery workforce: a survey of consultant vascular surgeons in the UK, 2014.

OBJECTIVE: The purpose of this study was to describe the demographics, training, and practice characteristics of consultant vascular surgeons across the UK to provide an assessment of current, and inform future prediction of workforce needs. METHODS: A questionnaire was developed using a modified Delphi process to generate questionnaire items. The questionnaire was emailed to all consultant vascular surgeons (n = 450) in the UK who were members of the Vascular Society of Great Britain & Ireland. RESULTS: 352 consultant vascular surgeons from 95 hospital trusts across the UK completed the survey (78% response rate). The mean age was 50.6 years old, the majority (62%) were mid-career, but 24% were above the age of 55. Currently, 92% are men and only 8% women. 93% work full-time, with 60% working >50 hours, and 21% working >60 hours per week. The average team was 5 to 6 (range 2-10) vascular surgeons, with 23% working in a large team of ≥8. 17% still work in small teams of ≤3. Over 90% of consultant vascular surgeons perform the major index vascular surgery procedures (aneurysm repair, carotid endarterectomy, infra-inguinal bypass, amputation). While 84% perform standard endovascular abdominal aortic aneurysm repair (EVAR), <50% perform more complex endovascular aortic therapy. The majority of vascular surgeons "like their job" (85%) and are "satisfied" (69%) with their job. 34% of consultant vascular surgeons indicated they were "extremely likely" to retire within the next 10 years. CONCLUSIONS: This study provides the first detailed analysis of the new specialty of vascular surgery as practiced in the UK. There is a need to plan for a significant expansion in the consultant vascular surgeon workforce in the UK over the next 10 years to maintain the status quo.

Risk Factors For Stroke, Myocardial Infarction, or Death Following Carotid Endarterectomy: Results From the International Carotid Stenting Study.

OBJECTIVES: Carotid endarterectomy (CEA) is standard treatment for symptomatic carotid artery stenosis but carries a risk of stroke, myocardial infarction (MI), or death. This study investigated risk factors for these procedural complications occurring within 30 days of endarterectomy in the International Carotid Stenting Study (ICSS). METHODS: Patients with recently symptomatic carotid stenosis >50% were randomly allocated to endarterectomy or stenting. Analysis is reported of patients in ICSS assigned to endarterectomy and limited to those in whom CEA was initiated. The occurrence of stroke, MI, or death within 30 days of the procedure was reported by investigators and adjudicated. Demographic and technical risk factors for these complications were analysed sequentially in a binomial regression analysis and subsequently in a multivariable model. RESULTS: Eight-hundred and twenty-one patients were included in the analysis. The risk of stroke, MI, or death within 30 days of CEA was 4.0%. The risk was higher in female patients (risk ratio [RR] 1.98, 95% CI 1.02-3.87, p = .05) and with increasing baseline diastolic blood pressure (dBP) (RR 1.30 per +10 mmHg, 95% CI 1.02-1.66, p = .04). Mean baseline dBP, obtained at the time of randomization in the trial, was 78 mmHg (SD 13 mmHg). In a multivariable model, only dBP remained a significant predictor. The risk was not related to the type of surgical reconstruction, anaesthetic technique, or perioperative medication regimen. Patients undergoing CEA stayed a median of 4 days before discharge, and 21.2% of events occurred on or after the day of discharge. CONCLUSIONS: Increasing diastolic blood pressure was the only independent risk factor for stroke, MI, or death following CEA. Cautious attention to blood pressure control following symptoms attributable to carotid stenosis could reduce the risks associated with subsequent CEA.

Randomized clinical trial comparing Nordic pole walking and a standard home exercise programme in patients with intermittent claudication.

BACKGROUND: This was a randomized clinical trial to determine whether Nordic pole walking (NPW) is more effective in improving walking distance than a standard home exercise programme (HEP) in patients with intermittent claudication. METHODS: Fifty-two patients with stable claudication were allocated randomly to a standard HEP or NPW group, and asked to complete three 30-min walks per week for 12 weeks. Claudication distance (CD) and maximum walking distance (MWD) were measured at 0 (baseline), 4, 8 and 12 weeks. Patients in the NPW group were tested with (NPW+) and without (NPW-) poles. RESULTS: For NPW+, CD increased immediately from a median (range) of 124 (71-248) m to 148 (116-426) m, and MWD from 248 (149-900) to 389 (194-1099) m (P = 0.004 and P < 0.001 respectively). By 12 weeks, CD had further increased to 199 (118-550) m and MWD had more than doubled to 538 (250-1750) m (P < 0.001 and P = 0.001). For NPW-, CD at 12 weeks had increased significantly to 151 (100-328) m and MWD to 400 (200-900) m (P < 0.001 and P = 0.006 respectively). At 12 weeks the changes in the standard HEP group were not significant, despite excellent compliance: CD from 107 (56-332) to 153 (59-321) m and MWD from 355 (92-600) to 334 (149-874) m (P = 0.030 and P = 0.260 respectively). CONCLUSION: A 12-week exercise programme using Nordic poles significantly improved walking distance in claudicants compared with a standard HEP. REGISTRATION NUMBER: ISRCTN78168304 (http://www.controlled-trials.com).

Pace of Aging in older adults matters for healthspan and lifespan.

As societies age, policy makers need tools to understand how demographic aging will affect population health and to develop programs to increase healthspan. The current metrics used for policy analysis do not distinguish differences caused by early-life factors, such as prenatal care and nutrition, from those caused by ongoing changes in people's bodies due to aging. Here we introduce an adapted Pace of Aging method designed to quantify differences between individuals and populations in the speed of aging-related health declines. The adapted Pace of Aging method, implemented in data from N=13,626 older adults in the US Health and Retirement Study, integrates longitudinal data on blood biomarkers, physical measurements, and functional tests. It reveals stark differences in rates of aging between population subgroups and demonstrates strong and consistent prospective associations with incident morbidity, disability, and mortality. Pace of Aging can advance the population science of healthy longevity.

Randomized trial of the effect of video feedback on the acquisition of surgical skills.

BACKGROUND: Constructive feedback provides a mechanism for reinforcing learning during the acquisition of surgical skills. Feedback is usually given verbally, and sometimes documented, after direct observation by a trained assessor. The aim was to evaluate video recording as an effective modality for enhancing feedback, in comparison with standard verbal feedback alone. METHODS: This was a prospective, blinded, randomized clinical trial comparing standard verbal feedback plus video with standard verbal feedback alone. Validated pro formas for assessment were used and quality control was performed by independent expert assessors. Trial participants were recorded on video performing the surgical skill, and returned the next day to perform the skill again following video and standard verbal feedback (group 1) or standard verbal feedback alone (group 2). RESULTS: Forty-eight participants were divided equally between the two groups. There was a significant improvement in the mean overall procedure score for group 1 of 2·875 from a maximum achievable score of 20 (P = 0·003), but not for group 2. There were significant improvements in the specific domains of instrument familiarity, needle handling, skin handling and accurate apposition, again all in group 1. The only significant improvement in group 2 was in an organized approach to the task, also observed in group 1. Knot-tying security deteriorated after feedback in group 2 but not in group 1. CONCLUSION: The addition of video feedback can improve the acquisition of surgical skills, and could be incorporated into formal surgical curricula.

Systematic review of home-based exercise programmes for individuals with intermittent claudication.

We aimed to conduct a systematic review of the evidence for structured, home-based exercise programmes (HEPs) in patients with intermittent claudication. The Medline, PsycINFO, EMBASE, and Cochrane databases were searched up to April 2013 for terms related to walking, self-management, and intermittent claudication. Descriptive, methodological and outcome data were extracted from eligible articles. Trial quality was assessed using the GRADE system. Seventeen studies were included with 1,457 participants. Six studies compared HEPs with supervised exercise training, five compared HEPs with usual care/observation control, and seven evaluated HEPs in a single-group design. Trial heterogeneity prevented meta-analysis. Nevertheless, there was "low-level" evidence that HEPs can improve walking capacity and quality of life in patients with intermittent claudication when compared with baseline or in comparison to usual care/observation control. In addition, improvements with HEPs may be inferior to those evoked by supervised exercise training. Considerable uncertainty exists regarding the long-term clinical and cost effectiveness of HEPs in patients with intermittent claudication. Thus, more robust trials are needed to build evidence about these interventions. Nevertheless, clinicians should consider using structured interventions to promote self-managed walking in patients with intermittent claudication, as opposed to simple "go home and walk" advice, when supervised exercise training is unavailable or impractical.

Travelling with tea: a Tuckerella's tale.

Tuckerella japonica Ehara appears strongly associated with tea (Camellia sinensis (L.) Kuntze, Theaceae) and, due to certain cultural practices in tea production, has in fact become a world traveller, accompanying the greatly coveted tea plant as it spread across the planet. The history of tea production and culture, and its arrival in the USA, provides the backdrop for this traveller's tale. Tuckerella japonica is morphologically similar to T. flabellifera Miller, described from Tasmania in Australia from Bedfordia salicina (Labill.) D.G. (Asteraceae). These two species have historically been misidentified as each other, creating inaccuracies in the collection records. The implications of this in terms of host plant lists and world distribution are discussed further, along with their morphological separation. The male and immature stages of T. japonica are described for the first time. Tuckerella xinglongensis Lin and Fu, from tea in China, is considered a junior synonym of T. japonica. The loss of the ancestral prostigmatan condition of three nymphal stages during ontogeny is confirmed for males of T. flabellifera, which do not retain a tritonymphal stage.