Growth is a major component of fitness in all organisms, an important mediator of competitive interactions in plant communities, and a central determinant of yield in crops. Understanding what limits ...plant growth is therefore of fundamental importance to plant evolution, ecology, and crop science, but each discipline views the process from a different perspective. This review highlights the importance of source–sink interactions as determinants of growth. The evidence for source- and sink-limitation of growth, and the ways in which regulatory molecular feedback systems act to maintain an appropriate source:sink balance, are first discussed. Evidence clearly shows that future increases in crop productivity depend crucially on a quantitative understanding of the extent to which sources or sinks limit growth, and how this changes during development. To identify bottlenecks limiting growth and yield, a holistic view of growth is required at the whole-plant scale, incorporating mechanistic interactions between physiology, resource allocation, and plant development. Such a holistic perspective on source–sink interactions will allow the development of a more integrated, whole-system level understanding of growth, with benefits across multiple disciplines.
The electrocatalytic reduction of carbon dioxide, powered by renewable electricity, to produce valuable fuels and feedstocks provides a sustainable and carbon-neutral approach to the storage of ...energy produced by intermittent renewable sources1. However, the highly selective generation of economically desirable products such as ethylene from the carbon dioxide reduction reaction (CO2RR) remains a challenge2. Tuning the stabilities of intermediates to favour a desired reaction pathway can improve selectivity3-5, and this has recently been explored for the reaction on copper by controlling morphology6, grain boundaries7, facets8, oxidation state9 and dopants10. Unfortunately, the Faradaic efficiency for ethylene is still low in neutral media (60 per cent at a partial current density of 7 milliamperes per square centimetre in the best catalyst reported so far9), resulting in a low energy efficiency. Here we present a molecular tuning strategy-the functionalization of the surface of electrocatalysts with organic molecules-that stabilizes intermediates for more selective CO2RR to ethylene. Using electrochemical, operando/in situ spectroscopic and computational studies, we investigate the influence of a library of molecules, derived by electro-dimerization of arylpyridiniums11, adsorbed on copper. We find that the adhered molecules improve the stabilization of an 'atop-bound' CO intermediate (that is, an intermediate bound to a single copper atom), thereby favouring further reduction to ethylene. As a result of this strategy, we report the CO2RR to ethylene with a Faradaic efficiency of 72 per cent at a partial current density of 230 milliamperes per square centimetre in a liquid-electrolyte flow cell in a neutral medium. We report stable ethylene electrosynthesis for 190 hours in a system based on a membrane-electrode assembly that provides a full-cell energy efficiency of 20 per cent. We anticipate that this may be generalized to enable molecular strategies to complement heterogeneous catalysts by stabilizing intermediates through local molecular tuning.
To evaluate the prevalence of burnout and satisfaction with work-life balance in physicians and US workers in 2014 relative to 2011.
From August 28, 2014, to October 6, 2014, we surveyed both US ...physicians and a probability-based sample of the general US population using the methods and measures used in our 2011 study. Burnout was measured using validated metrics, and satisfaction with work-life balance was assessed using standard tools.
Of the 35,922 physicians who received an invitation to participate, 6880 (19.2%) completed surveys. When assessed using the Maslach Burnout Inventory, 54.4% (n=3680) of the physicians reported at least 1 symptom of burnout in 2014 compared with 45.5% (n=3310) in 2011 (P<.001). Satisfaction with work-life balance also declined in physicians between 2011 and 2014 (48.5% vs 40.9%; P<.001). Substantial differences in rates of burnout and satisfaction with work-life balance were observed by specialty. In contrast to the trends in physicians, minimal changes in burnout or satisfaction with work-life balance were observed between 2011 and 2014 in probability-based samples of working US adults, resulting in an increasing disparity in burnout and satisfaction with work-life balance in physicians relative to the general US working population. After pooled multivariate analysis adjusting for age, sex, relationship status, and hours worked per week, physicians remained at an increased risk of burnout (odds ratio, 1.97; 95% CI, 1.80-2.16; P<.001) and were less likely to be satisfied with work-life balance (odds ratio, 0.68; 95% CI, 0.62-0.75; P<.001).
Burnout and satisfaction with work-life balance in US physicians worsened from 2011 to 2014. More than half of US physicians are now experiencing professional burnout.
Purpose
Ideally, a referral from a primary care physician (PCP) to a specialist results in a completed specialty appointment with results available to the PCP. This is defined as “closing the ...referral loop.” As health systems grow more complex, regulatory bodies increase vigilance, and reimbursement shifts towards value, closing the referral loop becomes a patient safety, regulatory, and financial imperative.
Objective/Design
To assess the ability of a large health system to close the referral loop, we used electronic medical record (EMR)-generated data to analyze referrals from a large primary care network to 20 high-volume specialties between July 1, 2015 and June 30, 2016.
Main Measures
The primary metric was documented specialist appointment completion rate. Explanatory analyses included documented appointment scheduling rate, individual clinic differences, appointment wait times, and geographic distance to appointments.
Key Results
Of the 103,737 analyzed referral scheduling attempts, only 36,072 (34.8%) resulted in documented complete appointments. Low documented appointment scheduling rates (38.9% of scheduling attempts lacked appointment dates), individual clinic differences in closing the referral loop, and significant differences in wait times and distances to specialists between complete and incomplete appointments drove this gap. Other notable findings include high variation in wait times among specialties and correlation between high wait times and low documented appointment completion rates.
Conclusions
The rate of closing the referral loop in this health system is low. Low appointment scheduling rates, individual clinic differences, and patient access issues of wait times and geographic proximity explain much of the gap. This problem is likely common among large health systems with complex provider networks and referral scheduling. Strategies that improve scheduling, decrease variation among clinics, and improve patient access will likely improve rates of closing the referral loop. More research is necessary to determine the impact of these changes and other potential driving factors.
Recent developments in observational near‐surface air temperature and sea‐surface temperature analyses are combined to produce HadCRUT4, a new data set of global and regional temperature evolution ...from 1850 to the present. This includes the addition of newly digitized measurement data, both over land and sea, new sea‐surface temperature bias adjustments and a more comprehensive error model for describing uncertainties in sea‐surface temperature measurements. An ensemble approach has been adopted to better describe complex temporal and spatial interdependencies of measurement and bias uncertainties and to allow these correlated uncertainties to be taken into account in studies that are based upon HadCRUT4. Climate diagnostics computed from the gridded data set broadly agree with those of other global near‐surface temperature analyses. Fitted linear trends in temperature anomalies are approximately 0.07°C/decade from 1901 to 2010 and 0.17°C/decade from 1979 to 2010 globally. Northern/southern hemispheric trends are 0.08/0.07°C/decade over 1901 to 2010 and 0.24/0.10°C/decade over 1979 to 2010. Linear trends in other prominent near‐surface temperature analyses agree well with the range of trends computed from the HadCRUT4 ensemble members.
Key Points
Updated version of a global temperature data set
An ensemble approach is adopted to describe correlated uncertainties
Improved estimates of uncertainty in global and regional temperature timeseries
Physician distress is common and has been associated with negative effects on patient care. However, factors associated with resident distress and well-being have not been well described at a ...national level.
To measure well-being in a national sample of internal medicine residents and to evaluate relationships with demographics, educational debt, and medical knowledge.
Study of internal medicine residents using data collected on 2008 and 2009 Internal Medicine In-Training Examination (IM-ITE) scores and the 2008 IM-ITE survey. Participants were 16,394 residents, representing 74.1% of all eligible US internal medicine residents in the 2008-2009 academic year. This total included 7743 US medical graduates and 8571 international medical graduates.
Quality of life (QOL) and symptoms of burnout were assessed, as were year of training, sex, medical school location, educational debt, and IM-ITE score reported as percentage of correct responses.
Quality of life was rated "as bad as it can be" or "somewhat bad" by 2402 of 16,187 responding residents (14.8%). Overall burnout and high levels of emotional exhaustion and depersonalization were reported by 8343 of 16,192 (51.5%), 7394 of 16,154 (45.8%), and 4541 of 15,737 (28.9%) responding residents, respectively. In multivariable models, burnout was less common among international medical graduates than among US medical graduates (45.1% vs 58.7%; odds ratio, 0.70 99% CI, 0.63-0.77; P < .001). Greater educational debt was associated with the presence of at least 1 symptom of burnout (61.5% vs 43.7%; odds ratio, 1.72 99% CI, 1.49-1.99; P < .001 for debt >$200,000 relative to no debt). Residents reporting QOL "as bad as it can be" and emotional exhaustion symptoms daily had mean IM-ITE scores 2.7 points (99% CI, 1.2-4.3; P < .001) and 4.2 points (99% CI, 2.5-5.9; P < .001) lower than those with QOL "as good as it can be" and no emotional exhaustion symptoms, respectively. Residents reporting debt greater than $200,000 had mean IM-ITE scores 5.0 points (99% CI, 4.4-5.6; P < .001) lower than those with no debt. These differences were similar in magnitude to the 4.1-point (99% CI, 3.9-4.3) and 2.6-point (99% CI, 2.4-2.8) mean differences associated with progressing from first to second and second to third years of training, respectively.
In this national study of internal medicine residents, suboptimal QOL and symptoms of burnout were common. Symptoms of burnout were associated with higher debt and were less frequent among international medical graduates. Low QOL, emotional exhaustion, and educational debt were associated with lower IM-ITE scores.
Plant domestication through an ecological lens Milla, Rubén; Osborne, Colin P.; Turcotte, Martin M. ...
Trends in ecology & evolution (Amsterdam),
08/2015, Letnik:
30, Številka:
8
Journal Article
Recenzirano
•Ecology is an underexploited science in the study of crop evolution.•A framework is provided to analyze ecological causes and effects of domestication.•Single traits and whole phenotypes react to ...natural selection under cultivation.•Domesticates exert relevant effects on ecosystem processes and co-occurring species.
Our understanding of domestication comes largely from archeology and genetics. Here, we advocate using current ecological theory and methodologies to provide novel insights into the causes and limitations of evolution under cultivation, as well as into the wider ecological impacts of domestication. We discuss the importance of natural selection under cultivation, that is, the forces promoting differences in Darwinian fitness between plants in crop populations and of constraints, that is, limitations of diverse nature that, given values for trait X, shorten the range of variation of trait Y, during the domestication process. Throughout this opinion paper, we highlight how ecology can yield insight into the effects of domestication on plant traits, on crop feedback over ecological processes, and on how species interactions develop in croplands.
ABSTRACT Protoplanetary disks (PPDs) are believed to accrete onto their central T Tauri star because of magnetic stresses. Recently published shearing box simulations indicate that Ohmic resistivity, ...ambipolar diffusion (AD) and the Hall effect all play important roles in disk evolution. In the presence of a vertical magnetic field, the disk remains laminar between 1- , and a magnetocentrifugal disk wind forms that provides an important mechanism for removing angular momentum. Questions remain, however, about the establishment of a true physical wind solution in the shearing box simulations because of the symmetries inherent in the local approximation. We present global MHD simulations of PPDs that include Ohmic resistivity and AD, where the time-dependent gas-phase electron and ion fractions are computed under FUV and X-ray ionization with a simplified recombination chemistry. Our results show that the disk remains laminar, and that a physical wind solution arises naturally in global disk models. The wind is sufficiently efficient to explain the observed accretion rates. Furthermore, the ionization fraction at intermediate disk heights is large enough for magneto-rotational channel modes to grow and subsequently develop into belts of horizontal field. Depending on the ionization fraction, these can remain quasi-global, or break-up into discrete islands of coherent field polarity. The disk models we present here show a dramatic departure from our earlier models including Ohmic resistivity only. It will be important to examine how the Hall effect modifies the evolution, and to explore the influence this has on the observational appearance of such systems, and on planet formation and migration.
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