Thermal acclimation of leaf and root respiration: an investigation comparing inherently fast- and slow-growing plant species

We investigated the extent to which leaf and root respiration W differ in their response to short- and long-term changes in temperature in several contrasting plant species (herbs, grasses, shrubs and trees) that differ in inherent relative growth rate (RGR, increase in mass per unit starting mass and time). Two experiments were conducted using hydroponically grown plants. In the long-term (LT) acclimation experiment, 16 species were grown at constant 18,23 and 28degreesC. In the short-term (ST) acclimation experiment, 9 of those species were grown at 25/20degreesC (day/night) and then shifted to a 15/10degreesC for 7 days. Short-term Q(10) values (proportional change in R per 10degreesC) and the degree of acclimation to. longer-term changes in temperature were compared. The effect of growth temperature on root and leaf soluble sugar and nitrogen concentrations was examined. Light-saturated photosynthesis (A(sat)) was also measured in the LT acclimation experiment. Our results show that Q(10) values and the degree of acclimation are highly variable amongst species and that roots exhibit lower Q(10) values than leaves over the 15-25degreesC measurement temperature range. Differences in RGR or concentrations of soluble sugars/nitrogen could not account for the inter-specific differences in the Q(10) or degree of acclimation. There were no systematic differences in the ability of roots and leaves to acclimate when plants developed under contrasting temperatures (LT acclimation). However, acclimation was greater in both leaves and roots that developed at the growth temperature (LT acclimation) than in pre-existing leaves and roots shifted from one temperature to another (ST acclimation). The balance between leaf R and A(sat) was maintained in plants grown at different temperatures, regardless of their inherent relative growth rate. We conclude that there is tight coupling between the respiratory acclimation and the temperature under which leaves and roots developed and that acclimation plays an important role in determining the relationship between respiration and photosynthesis

DESIGN AND ANALYSIS OF 2.56 GBPS CML CMOS TRANSCEIVER WITH SPECIFIC LOAD FOR PHYSICAL INSTRUMENTATION APPLICATIONS

In the work we describe the process of designing 2.56 Gbps CML receiver and 1.28 Gbps CML transmitter with specific transmission line properties. The blocks have been designed for the specific need of high speed data transmission in the radiation environment. Signal integrity is also analyzed

Two-divisibility of the coefficients of certain weakly holomorphic modular forms

We study a canonical basis for spaces of weakly holomorphic modular forms of weights 12, 16, 18, 20, 22, and 26 on the full modular group. We prove a relation between the Fourier coefficients of modular forms in this canonical basis and a generalized Ramanujan tau-function, and use this to prove that these Fourier coefficients are often highly divisible by 2.Comment: Corrected typos. To appear in the Ramanujan Journa

Perceptions of the Impact of Positive Action in EU and non-EU Countries

yesAbstract: Around the world, inequalities exist around boundaries of race, social class, gender, disability, religious beliefs and sexual orientation, often resulting from past and current discriminatory practices. Governments have taken certain measures, including enacting policies such as positive action, to remedy such discrimination. This paper provides a comparative analysis of perceptions of the impact of positive action in seven EU and three non-EU countries. The study adopted participatory methods including consensus workshops, interviews and policy analysis to obtain data from designers of positive action. Findings are discussed, conclusions drawn and wide-ranging recommendations are made at the EC, individual countries and organisational levels

Methodological Challenges of Researching Positive Action Measures

This paper highlights some ofthe methodological challenges which have arisen in collecting data for an international study on positive action measures. It will describe strategies employed to encourage participation in the study from as wide a range of organisations and individuals using a mixed method approach. The paper will also discuss the methodological and sensitive issues related to this type of research in organisations and strategies adopted by the research team to ameliorate any problems that have arisen whilst maintaining trustworthiness and rigour in the study

Positive Action Measures Across Different Equality Grounds, Organisations and Sectors in European and Non-european Countries

yesAbstract: This article is based on a large-scale European Commission project on international perspectives on positive action measures. The paper presents an analysis of the perceptions of positive action held by respondents from all the countries participating in an international survey, focussing specifically upon differences across equality grounds, sector and organisation type. This paper will also provide examples of positive action being applied in European and non-European countries that participated in the study. The study adopted extensive literate and online survey to obtain data from designers of positive action. Findings are discussed, conclusions drawn and wide-ranging recommendations are made at the European Commission, individual countries and organisational levels

Functional trait variation related to gap dynamics in tropical moist forests: a vegetation modelling perspective

The conventional representation of Plant Functional Types (PFTs) in Dynamic Global Vegetation Models (DGVMs) is increasingly recognized as simplistic and lacking in predictive power. Key ecophysiological traits, including photosynthetic parameters, are typically assigned single values for each PFT while the substantial trait variation within PFTs is neglected. This includes continuous variation in response to environmental factors, and differences linked to spatial and temporal niche differentiation within communities. A much stronger empirical basis is required for the treatment of continuous plant functional trait variation in DGVMs. We analyse 431 sets of measurements of leaf and plant traits, including photosynthetic measurements, on evergreen angiosperm trees in tropical moist forests of Australia and China. Confining attention to tropical moist forests, our analysis identifies trait differences that are linked to vegetation dynamic roles. Coordination theory predicts that Rubisco- and electron-transport limited rates of photosynthesis are co-limiting under field conditions. The least-cost hypothesis predicts that air-to-leaf CO2 drawdown minimizes the combined costs per unit carbon assimilation of maintaining carboxylation and transpiration capacities. Aspects of these predictions are supported for within-community trait variation linked to canopy position, just as they are for variation along spatial environmental gradients. Trait differences among plant species occupying different structural and temporal niches may provide a basis for the ecophysiological representation of vegetation dynamics in next-generation DGVMs

Leaf- and cell-level carbon cycling responses to a nitrogen and phosphorus gradient in two Arctic tundra species

Premise of the study: Consequences of global climate change are detectable in the historically nitrogen- and phosphorus-limited Arctic tundra landscape and have implications for the terrestrial carbon cycle. Warmer temperatures and elevated soil nutrient availability associated with increased microbial activity may influence rates of photosynthesis and respiration. Methods: This study examined leaf-level gas exchange, cellular ultrastructure, and related leaf traits in two dominant tundra species, Betula nana, a woody shrub, and Eriophorum vaginatum, a tussock sedge, under a 3-yr-old treatment gradient of nitrogen (N) and phosphorus (P) fertilization in the North Slope of Alaska. Key results: Respiration increased with N and P addition—the highest rates corresponding to the highest concentrations of leaf N in both species. The inhibition of respiration by light ("Kok effect") significantly reduced respiration rates in both species (P < 0.001), ranged from 12–63% (mean 34%), and generally decreased with fertilization for both species. However, in both species, observed rates of photosynthesis did not increase, and photosynthetic nitrogen use efficiency generally decreased under increasing fertilization. Chloroplast and mitochondrial size and density were highly sensitive to N and P fertilization (P < 0.001), though species interactions indicated divergent cellular organizational strategies. Conclusions: Results from this study demonstrate a species-specific decoupling of respiration and photosynthesis under N and P fertilization, implying an alteration of the carbon balance of the tundra ecosystem under future conditions

Enterprise placements: factors which support learning and prolonged attainment in students

This article investigates the learning and academic attainment of undergraduate education students on enterprise placement projects in a longitudinal mixed methods study. By observing the placement learning and analysing previous and subsequent attainment of a second and third year group it adds to the ontology of purpose for enterprise in education and concurs with the growing body of work identifying placements with sustained academic improvement. The qualitative investigation identifies five key learning factors from the placements which support improved academic attainment. These are: pressure to learn; critical personal learning events; seeing the setting as a learning environment; professional attachments, and having space to learn. These factors support the transfer of learning from one context or situation to another and using concepts of transformative learning (Mezirow 2000; Jones, Matlay, and Harris 2012) or transitional learning (Illeris 2007) contributes to a cycle of increasing self-esteem and motivation and a sustained improvement in academic attainment. It concludes that a praxis curriculum, using self-assessments, continuous short (micro) reflections and taught awareness of the placement as a place to look for and recognise learning, would underpin these five factors and contribute to the academic processes underpinning attainment