Is stimulation of leaf photosynthesis by elevated carbon dioxide concentration maintained in the long term? A test with Lolium perenne grown for 10 years at two nitrogen fertilization levels under Free Air CO2 Enrichment (FACE)

Photosynthesis is commonly stimulated in grasslands with experimental increases in atmospheric CO2 concentration ([CO2]), a physiological response that could significantly alter the future carbon cycle if it persists in the long term.. Yet an acclimation of photosynthetic capacity suggested by theoretical models and short-term experiments could completely remove this effect of CO2. Perennial ryegrass (Lolium perenne L. cv. Bastion) was grown under an elevated [CO2] of 600 mumol mol(-1) for 10 years using Free Air CO2 Enrichment (FACE), with two contrasting nitrogen levels and abrupt changes in the source: sink ratio following periodic harvests. More than 3000 measurements characterized the response of leaf photosynthesis and stomatal conductance to elevated [CO2] across each growing season for the duration of the experiment. Over the 10 years as a whole, growth at elevated [CO2] resulted in a 43% higher rate of light-saturated leaf photosynthesis and a 36% increase in daily integral of leaf CO2 uptake. Photosynthetic stimulation was maintained despite a 30% decrease in stomatal conductance and significant decreases in both the apparent, maximum carboxylation velocity (V-c,V-max) and the maximum rate of electron transport (J(max)). Immediately prior to the periodic (every 4-8 weeks) cuts of the L. perenne stands, V-c,V-max and J(max), were significantly lower in elevated than in ambient [CO2] in the low-nitrogen treatment. This difference was smaller after the cut, suggesting a dependence upon the balance between the sources and sinks for carbon. In contrast with theoretical expectations and the results of shorter duration experiments, the present results provide no significant change in photosynthetic stimulation across a 10-year period, nor greater acclimation in V-c,V-max and J(max) in the later years in either nitrogen treatment

Long-Time Asymptotics for Solutions of the NLS Equation with a Delta Potential and Even Initial Data

We consider the one-dimensional focusing nonlinear Schr\"odinger equation (NLS) with a delta potential and even initial data. The problem is equivalent to the solution of the initial/boundary problem for NLS on a half-line with Robin boundary conditions at the origin. We follow the method of Bikbaev and Tarasov which utilizes a B\"acklund transformation to extend the solution on the half-line to a solution of the NLS equation on the whole line. We study the asymptotic stability of the stationary 1-soliton solution of the equation under perturbation by applying the nonlinear steepest-descent method for Riemann-Hilbert problems introduced by Deift and Zhou. Our work strengthens, and extends, earlier work on the problem by Holmer and Zworski

Reflection and Ducting of Gravity Waves Inside the Sun

Internal gravity waves excited by overshoot at the bottom of the convection zone can be influenced by rotation and by the strong toroidal magnetic field that is likely to be present in the solar tachocline. Using a simple Cartesian model, we show how waves with a vertical component of propagation can be reflected when traveling through a layer containing a horizontal magnetic field with a strength that varies with depth. This interaction can prevent a portion of the downward-traveling wave energy flux from reaching the deep solar interior. If a highly reflecting magnetized layer is located some distance below the convection zone base, a duct or wave guide can be set up, wherein vertical propagation is restricted by successive reflections at the upper and lower boundaries. The presence of both upward- and downward-traveling disturbances inside the duct leads to the existence of a set of horizontally propagating modes that have significantly enhanced amplitudes. We point out that the helical structure of these waves makes them capable of generating an alpha-effect, and briefly consider the possibility that propagation in a shear of sufficient strength could lead to instability, the result of wave growth due to over-reflection.Comment: 23 pages, 5 figures. Accepted for publication in Solar Physic

A solar-powered reverse osmosis system for high recovery of freshwater from saline groundwater

Desalination of groundwater is essential in arid regions that are remote from both seawater and freshwater resources. Desirable features of a groundwater desalination system include a high recovery ratio, operation from a sustainable energy source such as solar, and high water output per unit of energy and land. Here we propose a new system that uses a solar-Rankine cycle to drive reverse osmosis (RO). The working fluid such as steam is expanded against a power piston that actuates a pump piston which in turn pressurises the saline water thus passing it through RO membranes. A reciprocating crank mechanism is used to equalise the forces between the two pistons. The choice of batch mode in preference to continuous flow permits maximum energy recovery and minimal concentration polarisation in the vicinity of the RO membrane. This study analyses the sizing and efficiency of the crank mechanism, quantifies energy losses in the RO separation and predicts the overall performance. For example, a system using a field of linear Fresnel collectors occupying 1000 m2 of land and raising steam at 200 °C and 15.5 bar could desalinate 350 m3/day from saline water containing 5000 ppm of sodium chloride with a recovery ratio of 0.7

Moral reasoning and homosexuality: the acceptability of arguments about lesbian and gay issues

In the political arena, lesbian and gay issues have typically been contested on grounds of human rights, but with variable success. Using a moral developmental framework, the purpose of this study was to explore preferences for different types of moral arguments when thinking about moral dilemmas around lesbian and gay issues. The analysis presented here comprised data collected from 545 students at UK universities, who completed a questionnaire, part of which comprised a moral dilemma task. Findings of the study showed that respondents do not apply moral reasoning consistently, and do not (clearly) favour human rights reasoning when thinking about lesbian and gay issues. Respondents tended to favour reasoning supporting existing social structures and frameworks, therefore this study highlights the importance of structural change in effecting widespread attitude change in relation to lesbian and gay rights issues. The implications of the findings for moral education are also discussed.</p

Foundations of population-based SHM, Part I : homogeneous populations and forms

In Structural Health Monitoring (SHM), measured data that correspond to an extensive set of operational and damage conditions (for a given structure) are rarely available. One potential solution considers that information might be transferred, in some sense, between similar systems. A population-based approach to SHM looks to both model and transfer this missing information, by considering data collected from groups of similar structures. Specifically, in this work, a framework is proposed to model a population of nominally-identical systems, such that (complete) datasets are only available from a subset of members. The SHM strategy defines a general model, referred to as the population form, which is used to monitor a homogeneous group of systems. First, the framework is demonstrated through applications to a simulated population, with one experimental (test-rig) member; the form is then adapted and applied to signals recorded from an operational wind farm

Monitoring and evaluation of spatially managed areas: a generic framework and its application

The application of an ecosystem approach to management of the sea requires both integrated and strategic frameworks such as Integrated Coastal Zone Management (ICZM) and the use of marine spatial planning (MSP) to minimize spatial use conflicts and environmental degradation. Such an integrated management promotes sustainable development based on achieving a balance of environmental, social and economic objectives. Here we introduce a first draft of a generic framework which is developed in the EU FP7 project MESMA that gives guidance on how to assess the effectiveness of an existing management within a spatially defined area. More precisely, we define spatially managed areas as geographical entities where a marine planning framework is or will be used to manage multiple human activities in space and time while aiming to maintain ecosystem integrity. The framework consists of seven steps and comprises practical guidance on the selection of operational objectives and related criteria (step 1), the collation and integration of information (steps 2, 3 and 4), performance assessment (step 5), and feedback processes (steps 6 and 7). In the course of the MESMA project, this generic framework will be applied and tested in nine case studies, representing all European seas. Here we highlight the processes and practical tasks involved in each of the framework steps, reflect on the first attempts to implement this framework and identify the requirements for practical tools such as standardized methods to map human activities and assess their cumulative impacts

Searches for solar-influenced radioactive decay anomalies using Spacecraft RTGs

Experiments showing a seasonal variation of the nuclear decay rates of a number of different nuclei, and decay anomalies apparently related to solar flares and solar rotation, have suggested that the Sun may somehow be influencing nuclear decay processes. Recently, Cooper searched for such an effect in $^{238}$Pu nuclei contained in the radioisotope thermoelectric generators (RTGs) on board the Cassini spacecraft. In this paper we modify and extend Cooper's analysis to obtain constraints on anomalous decays of $^{238}$Pu over a wider range of models, but these limits cannot be applied to other nuclei if the anomaly is composition-dependent. We also show that it may require very high sensitivity for terrestrial experiments to discriminate among some models if such a decay anomaly exists, motivating the consideration of future spacecraft experiments which would require less precision.Comment: 8 pages, 4 figures (to appear in Astroparticle Physics

Cloud microphysical effects of turbulent mixing and entrainment

Turbulent mixing and entrainment at the boundary of a cloud is studied by means of direct numerical simulations that couple the Eulerian description of the turbulent velocity and water vapor fields with a Lagrangian ensemble of cloud water droplets that can grow and shrink by condensation and evaporation, respectively. The focus is on detailed analysis of the relaxation process of the droplet ensemble during the entrainment of subsaturated air, in particular the dependence on turbulence time scales, droplet number density, initial droplet radius and particle inertia. We find that the droplet evolution during the entrainment process is captured best by a phase relaxation time that is based on the droplet number density with respect to the entire simulation domain and the initial droplet radius. Even under conditions favoring homogeneous mixing, the probability density function of supersaturation at droplet locations exhibits initially strong negative skewness, consistent with droplets near the cloud boundary being suddenly mixed into clear air, but rapidly approaches a narrower, symmetric shape. The droplet size distribution, which is initialized as perfectly monodisperse, broadens and also becomes somewhat negatively skewed. Particle inertia and gravitational settling lead to a more rapid initial evaporation, but ultimately only to slight depletion of both tails of the droplet size distribution. The Reynolds number dependence of the mixing process remained weak over the parameter range studied, most probably due to the fact that the inhomogeneous mixing regime could not be fully accessed when phase relaxation times based on global number density are considered.Comment: 17 pages, 10 Postscript figures (figures 3,4,6,7,8 and 10 are in reduced quality), to appear in Theoretical Computational Fluid Dynamic

Association Between Side of Living Kidney Donation and Post-Transplant Outcomes

Background: Right-sided living donor kidneys have longer renal arteries and shorter veins that make vascular anastomosis more challenging. We sought to determine whether recipients of right-sided living donor kidneys have worse outcomes than left-sided kidney recipients. Methods: An observational analysis of the Australia and New Zealand Dialysis and Transplant Registry (ANZDATA) was undertaken. We used adjusted logistic regression to determine the association between side and delayed graft function (DGF) and timestratified adjusted cox regression models for graft and patient survivals. Results: Between 2004 and 2018, 4,050 living donor kidney transplants were conducted with 696 (17.2%) using right kidneys. With reference to left kidneys, the adjusted OR (95% CI) for DGF was 2.01 (1.31–3.09) for recipients with right kidneys. Within 30 days, 46 allografts (1.4%) were lost, with major causes of overall graft loss being technical, primary non-function and death. Recipients of right donor kidneys experienced a greater risk of early graft loss (aHR 2.02 [95% CI 1.06–3.86], p = 0.03), but not beyond 30 days (aHR 0.97 [95% CI 0.80–1.19], p = 0.8]). Conclusion: Technical challenge is the most common cause of early graft loss. The risk of early graft loss among recipients who received right kidneys is doubled compared to those who received left living donor kidneys.Ellen L. K. Dobrijevic, Eric H. K. Au, Natasha M. Rogers, Philip A. Clayton, Germaine Wong, and Richard D. M. Alle