Energy-dependent quenching adjusts the excitation diffusion length to regulate photosynthetic light harvesting

An important determinant of crop yields is the regulation of photosystem II (PSII) light harvesting by energy-dependent quenching (qE). However, the molecular details of excitation quenching have not been quantitatively connected to the PSII yield, which only emerges on the 100 nm scale of the grana membrane and determines flux to downstream metabolism. Here, we incorporate excitation dissipation by qE into a pigment-scale model of excitation transfer and trapping for a 200 nm x 200 nm patch of the grana membrane. We demonstrate that single molecule measurements of qE are consistent with a weak-quenching regime. Consequently, excitation transport can be rigorously coarse-grained to a 2D random walk with an excitation diffusion length determined by the extent of quenching. A diffusion-corrected lake model substantially improves the PSII yield determined from variable chlorophyll fluorescence measurements and offers an improved model of PSII for photosynthetic metabolism.Comment: 19 pages, 4 figures, 3 supplementary figure

A Superfield for Every Dash-Chromotopology

The recent classification scheme of so-called adinkraic off-shell supermultiplets of N-extended worldline supersymmetry without central charges finds a combinatorial explosion. Completing our earlier efforts, we now complete the constructive proof that all of these trillions or more of supermultiplets have a superfield representation. While different as superfields and supermultiplets, these are still super-differentially related to a much more modest number of minimal supermultiplets, which we construct herein.Comment: 13 pages, integrated illustration

The cost of youth suicide in Australia

© 2018 by the authors. Licensee MDPI, Basel, Switzerland. Suicide is the leading cause of death among Australians between 15 and 24 years of age. This study seeks to estimate the economic cost of youth suicide (15-24 years old) for Australia using 2014 as a reference year. The main outcome measure is monetized burden of youth suicide. Costs, in 2014 AU$, are measured and valued as direct costs, such as coronial inquiry, police, ambulance, and funeral expenses; indirect costs, such as lost economic productivity; and intangible costs, such as bereavement. In 2014, 307 young Australians lost their lives to suicide (82 females and 225 males). The average age at time of death was 20.4 years, representing an average loss of 62 years of life and close to 46 years of productive capacity. The average cost per youth suicide is valued at$2,884,426, including $9721 in direct costs,$2,788,245 as the value of lost productivity, and $86,460 as the cost of bereavement. The total economic loss of youth suicide in Australia is estimated at$22 billion a year (equivalent to US$17 billion), ranging from$20 to $25 billion. These findings can assist decision-makers understand the magnitude of adverse outcomes associated with youth suicide and the potential benefits to be achieved by investing in effective suicide prevention strategies

Theory Challenges of the Accelerating Universe

The accelerating expansion of the universe presents an exciting, fundamental challenge to the standard models of particle physics and cosmology. I highlight some of the outstanding challenges in both developing theoretical models and interpreting without bias the observational results from precision cosmology experiments in the next decade that will return data to help reveal the nature of the new physics. Examples given focus on distinguishing a new component of energy from a new law of gravity, and the effect of early dark energy on baryon acoustic oscillations.Comment: 10 pages, 4 figures; minor changes to match J. Phys. A versio

Mechanistic Regimes of Vibronic Transport in a Heterodimer and the Design Principle of Incoherent Vibronic Transport in Phycobiliproteins

Following the observation of coherent oscillations in non-linear spectra of photosynthetic pigment protein complexes, particularly phycobilliprotein such as PC645, coherent vibronic transport has been suggested as a design principle for novel light harvesting materials operating at room temperature. Vibronic transport between energetically remote pigments is coherent when the presence of a resonant vibration supports transient delocalization between the pair of electronic excited states. Here, we establish the mechanism of vibronic transport for a model heterodimer across a wide range of molecular parameter values. The resulting mechanistic map demonstrates that the molecular parameters of phycobiliproteins in fact support incoherent vibronic transport. This result points to an important design principle: incoherent vibronic transport is more efficient than a coherent mechanism when energetic disorder exceeds the coupling between the donor and vibrationally excited acceptor states. Finally, our results suggest that the role of coherent vibronic transport in pigment protein complexes should be reevaluated

Worldsheet Matter Superfields on Half-Shell

In this paper we discuss some of the effects of using "unidexterous" worldsheet superfields, which satisfy worldsheet differential constraints and so are partly on-shell, i.e., on half-shell. Most notably, this results in a stratification of the field space that reminds of "brane-world" geometries. Linear dependence on such superfields provides a worldsheet generalization of the super-Zeeman effect. In turn, non-linear dependence yields additional left-right asymmetric dynamical constraints on the propagating fields, again in a stratified fashion.Comment: 15 pages, 2 figures; minor algebraic correction

Can analyses of electronic patient records be independently and externally validated? The effect of statins on the mortality of patients with ischaemic heart disease: a cohort study with nested case-control analysis

Objective To conduct a fully independent and external validation of a research study based on one electronic health record database, using a different electronic database sampling the same population. Design Using the Clinical Practice Research Datalink (CPRD), we replicated a published investigation into the effects of statins in patients with ischaemic heart disease (IHD) by a different research team using QResearch. We replicated the original methods and analysed all-cause mortality using: (1) a cohort analysis and (2) a case-control analysis nested within the full cohort. Setting Electronic health record databases containing longitudinal patient consultation data from large numbers of general practices distributed throughout the UK. Participants CPRD data for 34 925 patients with IHD from 224 general practices, compared to previously published results from QResearch for 13 029 patients from 89 general practices. The study period was from January 1996 to December 2003. Results We successfully replicated the methods of the original study very closely. In a cohort analysis, risk of death was lower by 55% for patients on statins, compared with 53% for QResearch (adjusted HR 0.45, 95% CI 0.40 to 0.50; vs 0.47, 95% CI 0.41 to 0.53). In case-control analyses, patients on statins had a 31% lower odds of death, compared with 39% for QResearch (adjusted OR 0.69, 95% CI 0.63 to 0.75; vs OR 0.61, 95% CI 0.52 to 0.72). Results were also close for individual statins. Conclusions Database differences in population characteristics and in data definitions, recording, quality and completeness had a minimal impact on key statistical outputs. The results uphold the validity of research using CPRD and QResearch by providing independent evidence that both datasets produce very similar estimates of treatment effect, leading to the same clinical and policy decisions. Together with other non-independent replication studies, there is a nascent body of evidence for wider validity

Building Clinical Ethics Capacity, Final Report of the Developing Clinical Ethics Capacity in NSW Partnership project 2014

Clinical ethics support services are an established feature of health care in the US and Canada and are becoming so in the UK, France, Belgium and elsewhere in Europe. They are yet to be widely established in NSW or elsewhere Australia. Clinical ethics support typically involves the provision of expert ethics input into clinical education, policy development and the care of individual patients, particularly where this involves value, rather than clinical, or scientific, conflict. Ethics support is generally provided by an individual consultant, an ethics committee or some combination of the two. In its case consultation function, expert support is intended to clarify the values that are in tension and through promoting open and inclusive discussion, facilitate consensus on the appropriate next steps. Internationally, the guidance and recommendations issued by a support service on a particular case are, in most cases, advisory and not binding. Advocates argue that clinical ethics support is necessary because contemporary clinical work takes place in a technologically, socially and ethically complex environment. The medical encounter has become far more open to scrutiny and is accountable to a more diverse public holding often quite different interests, ideas and values. In a more pluralist society, professional training, professional codes and institutional polices aren’t sufficient to establish ethical practices and procedures or resolve the ethical dilemmas that arise in the care of individual patients. The ethics expertise provided by an ethicist or a panel of ethically trained clinicians is necessary to astutely appraise the values and arguments and generate consensus. Without such expertise the ethicality of practices cannot be assured. Clinical ethics support is intended to promote ethically sound clinical and organisational practices and decision-making and thereby contribute to health organisation and system quality improvement. The under-developed state of clinical ethics support in Australia and NSW prompted NSW Health, in partnership with the Centre of Values Ethics and Law in Medicine and the Centre for Health Law and Governance , to ask: 1. Do changes to the environment in which clinical practice occurs mean there is a need to change the way we deal with ethical dilemmas? 2. Is more formalised support for clinicians, when making difficult and possibly controversial ethical decisions, desirable or warranted? 3. If it is agreed that clinical ethics support should be enhanced, what model is most appropriate for local conditions?funding provided by the Centre for Epidemiology and Evidence, NSW Ministry of Healt