On the importance of including vegetation dynamics in Budyko's hydrological model

The Budyko curve describes the patterns observed between between climate, evapotranspiration and run-off and has proven to be a useful model for predicting catchment energy and water balances. In this paper we review the Budyko curve's underlying framework and, based on the literature, present an argument for why it is important to include vegetation dynamics into the framework for some purposes. The Budyko framework assumes catchments are at steady-state and are driven by the macro-climate, two conditions dependent on the scales of application, such that the framework's reliability is greatest when applied using long-term averages (≫1 year) and to large catchments (> 10 000 km2). At these scales previous experience has shown that the hydrological role of vegetation does not need to be explicitly considered within the framework. By demonstrating how dynamics in the leaf area, photosynthetic capacity and rooting depth of vegetation affect not only annual and seasonal vegetation water use, but also steady-state conditions, we argue that it is necessary to explicitly include vegetation dynamics into the Budyko framework before it is applied at small scales. Such adaptations would extend the framework not only to applications at small timescales and/or small catchments but to operational activities relating to vegetation and water management

A View of Poultry Production in the Americas

The primary goal of the presentation is to share a long-term overview of how broiler production has changed over the last 35 years in areas of bird performance, production costs, particularly in the area of feed ingredient cost per lb. and illustrating how poultry nutritionists have adapted feed formulations to meet the changes in performance and cost

A View of Poultry Production in the Americas

The primary goal of the presentation is to share a long-term overview of how broiler production has changed over the last 35 years in areas of bird performance, production costs, particularly in the area of feed ingredient cost per lb. and illustrating how poultry nutritionists have adapted feed formulations to meet the changes in performance and cost

Importance of long-term cycles for predicting water level dynamics in natural lakes

Lakes are disproportionately important ecosystems for humanity, containing 77% of the liquid surface freshwater on Earth and comprising key contributors to global biodiversity. With an ever-growing human demand for water and increasing climate uncertainty, there is pressing need for improved understanding of the underlying patterns of natural variability of water resources and consideration of their implications for water resource management and conservation. Here we use Bayesian harmonic regression models to characterise water level dynamics and study the influence of cyclic components in confounding estimation of long-term directional trends in water levels in natural Irish lakes. We found that the lakes were characterised by a common and well-defined annual seasonality and several inter-annual and inter-decadal cycles with strong transient behaviour over time. Importantly, failing to account for the longer-term cyclic components produced a significant overall underestimation of the trend effect. Our findings demonstrate the importance of contextualising lake water resource management to the specific physical setting of lakes

Impact of CO2 fertilization on maximum foliage cover across the globe's warm, arid environments

Satellite observations reveal a greening of the globe over recent decades. The role in this greening of the "CO2 fertilization" effect-the enhancement of photosynthesis due to rising CO2 levels-is yet to be established. The direct CO2 effect on vegetatio

Regression of ranked responses when raw responses are censored

We discuss semiparametric regression when only the ranks of responses are observed. The model is $Y_i = F (\mathbf{x}_i'{\boldsymbol\beta}_0 + \varepsilon_i)$, where $Y_i$ is the unobserved response, $F$ is a monotone increasing function, $\mathbf{x}_i$ is a known $p-$vector of covariates, ${\boldsymbol\beta}_0$ is an unknown $p$-vector of interest, and $\varepsilon_i$ is an error term independent of $\mathbf{x}_i$. We observe $\{(\mathbf{x}_i,R_n(Y_i)) : i = 1,\ldots ,n\}$, where $R_n$ is the ordinal rank function. We explore a novel estimator under Gaussian assumptions. We discuss the literature, apply the method to an Alzheimer's disease biomarker, conduct simulation studies, and prove consistency and asymptotic normality.Comment: 33 pages, 6 figure

Genre-based literacy pedagogy: the nature and value of genre knowledge in teaching and learning writing on a university first year media studies course

A thesis submitted to the Faculty of Humanities, Uniiversity of Luton, in partial fulfilment of the requirements for the degree of Doctor of PhilosophyIn the teaching and learning of literacy, descriptions of text have a problematic status as a result of the growing understanding of literacy as both a cognitive process and a social practice. In the teaching of academic subjects at university, student text is not usually an object of study. The research in this thesis draws on a language based theory oflearning to place textual description at the centre of the teaching and learning of both literacy and academic subjects at university. Participant observation and practice-based research methods were used to implement a form of text-oriented literacy teaching and to explore its compatibility with processes and practices orientations to literacy. Over an eighteen month period, systemic functional grammar was used to investigate and describe the texts of a film studies classroom and the descriptions were used in genre based literacy pedagogy. The effects of the pedagogy are measured in terms of students' performance in an end of course assignment, students' accounts of their writing processes, and student and subject-tutor perception of the text description and the pedagogy. In the thesis, a linguistic description of a key curriculum genre -a Taxonomic Film Analysis -is presented. An account is given of the pedagogy by means of which this essay genre was represented in the film studies classroom as a realisation of choices from linguistic, conceptual and activity systems. Systemic functional grammar-based text description is seen to have provided a means whereby a literacy tutor could collaborate with a subject tutor to provide a subject-specific form of literacy teaching which was evaluated as relevant by students and tutors. The account and the evaluation help to clarify the role that description of text can play in relation to processes and practices ofliteracy use in the teaching and learning of literacy in a film studies classroom and have implications for the teaching and learning of literacy at university more generally

Bayesian latent time joint mixed-effects model of progression in the Alzheimer's Disease Neuroimaging Initiative.

IntroductionWe characterize long-term disease dynamics from cognitively healthy to dementia using data from the Alzheimer's Disease Neuroimaging Initiative.MethodsWe apply a latent time joint mixed-effects model to 16 cognitive, functional, biomarker, and imaging outcomes in Alzheimer's Disease Neuroimaging Initiative. Markov chain Monte Carlo methods are used for estimation and inference.ResultsWe find good concordance between latent time and diagnosis. Change in amyloid positron emission tomography shows a moderate correlation with change in cerebrospinal fluid tau (ρ = 0.310) and phosphorylated tau (ρ = 0.294) and weaker correlation with amyloid-β 42 (ρ = 0.176). In comparison to amyloid positron emission tomography, change in volumetric magnetic resonance imaging summaries is more strongly correlated with cognitive measures (e.g., ρ = 0.731 for ventricles and Alzheimer's Disease Assessment Scale). The average disease trends are consistent with the amyloid cascade hypothesis.DiscussionThe latent time joint mixed-effects model can (1) uncover long-term disease trends; (2) estimate the sequence of pathological abnormalities; and (3) provide subject-specific prognostic estimates of the time until onset of symptoms

Assessing Post-ADA Employment: Some Econometric Evidence and Policy Considerations

This article explores the relationship between the Americans with Disabilities Act (“ADA”) and the relative labor market outcomes for people with disabilities. Using individual-level longitudinal data from 1981 to 1996 derived from the previously unexploited Panel Study of Income Dynamics (“PSID”), we examine the possible effect of the ADA on (1) annual weeks worked; (2) annual earnings; and (3) hourly wages for a sample of 7120 unique male household heads between the ages of 21 and 65 as well as a subset of 1437 individuals appearing every year from 1981 to 1996. Our analysis of the larger sample suggests the ADA had a negative impact on the employment levels of disabled persons relative to non-disabled persons but no impact on relative earnings. However, our evaluation of the restricted sample raises questions about these findings. Using these data, we find little evidence of adverse effects on weeks worked but strong evidence of wage declines for the disabled, albeit declines beginning in 1986, well before the ADA’s passage. These results therefore cast doubt on the adverse ADA-related impacts found in previous studies, particularly Acemoglu and Angrist (2001). The conflicting narratives that emerge from our analysis shed new light on, but also counsel caution in reaching final conclusions about, the impact of the ADA on employment outcomes for people with disabilities