3,726 research outputs found

    Making evaluations matter: a practical guide for evaluators

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    This guide is primarily for evaluators working in the international development sector. It is also useful for commissioner of evaluations, evaluation managers and M&E officers. The guide explains how to make evaluations more useful. It helps to better understand conceptual issues and appreciate how evaluations can contribute to changing mindsets and empowering stakeholders. On a practical level, the guide presents core guiding principles and pointers on how to design and facilitate evaluations that matter. Furthermore, it shows how to get primary intended users and other key stakeholders to contribute effectively to the evaluation proces

    Rotating black hole orbit functionals in the frequency domain

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    In many astrophysical problems, it is important to understand the behavior of functions that come from rotating (Kerr) black hole orbits. It can be particularly useful to work with the frequency domain representation of those functions, in order to bring out their harmonic dependence upon the fundamental orbital frequencies of Kerr black holes. Although, as has recently been shown by W. Schmidt, such a frequency domain representation must exist, the coupled nature of a black hole orbit's rr and θ\theta motions makes it difficult to construct such a representation in practice. Combining Schmidt's description with a clever choice of timelike coordinate suggested by Y. Mino, we have developed a simple procedure that sidesteps this difficulty. One first Fourier expands all quantities using Mino's time coordinate λ\lambda. In particular, the observer's time tt is decomposed with λ\lambda. The frequency domain description is then built from the λ\lambda-Fourier expansion and the expansion of tt. We have found this procedure to be quite simple to implement, and to be applicable to a wide class of functionals. We test the procedure using a simple test function, and then apply it in a particularly interesting case, the Weyl curvature scalar ψ4\psi_4 used in black hole perturbation theory.Comment: 16 pages, 2 figures. Submitted to Phys Rev D. New version gives a vastly improved algorithm due to Drasco for computing the Fourier transforms. Drasco has been added as an author. Also fixed some references and exterminated a small herd of typos; final published versio

    Contrasting patterns of litterfall seasonality and seasonal changes in litter decomposability in a tropical rainforest region

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    The seasonality of litter inputs in forests has important implications for understanding ecosystem processes and biogeochemical cycles. We quantified the drivers of seasonality in litterfall and leaf decomposability using plots throughout the Australian wet tropical region. Litter fell mostly in the summer (wet, warm) months in the region, but other peaks occurred throughout the year. Litterfall seasonality was modelled well with the level of deciduousness of the site (plots with more deciduous species had lower seasonality than evergreen plots), temperature (higher seasonality in the uplands), disturbance (lower seasonality with more early secondary species) and soil fertility (higher seasonality with higher N : P/P limitation) (SL total litterfall model 1 = deciduousness + soil N : P + early secondary sp.: r2 = 0.63, n = 30; model 2 = temperature + early secondary sp. + soil N : P: r2 = 0.54, n = 30; SL leaf = temperature + early secondary sp. + rainfall seasonality: r2 = 0.39, n = 30). Leaf litter decomposability was lower in the dry season than in the wet season, driven by higher phenolic concentrations in the dry, with the difference exacerbated particularly by lower dry season moisture. Our results are contrary to the global trend for tropical rainforests; in that seasonality of litterfall input was generally higher in wetter, cooler, evergreen forests, compared to generally drier, warmer, semi-deciduous sites that had more uniform monthly inputs. We consider this due to more diverse litter shedding patterns in semi-deciduous and raingreen rainforest sites, and an important consideration for ecosystem modellers. Seasonal changes in litter quality are likely to have impacts on decomposition and biogeochemical cycles in these forests due to the litter that falls in the dry season being more recalcitrant to decay

    Metabolite profiling of non-sterile rhizosphere soil

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    Rhizosphere chemistry is the sum of root exudation chemicals, their breakdown products and the microbial products of soil-derived chemicals. To date, most studies about root exudation chemistry are based on sterile cultivation systems, which limits the discovery of microbial breakdown products that act as semiochemicals and shape microbial rhizosphere communities. Here, we present a method for untargeted metabolic profiling of non-sterile rhizosphere soil. We have developed an experimental growth system that enables the collection and analysis of rhizosphere chemicals from different plant species. High-throughput sequencing of 16SrRNA genes demonstrated that plants in the growth system support a microbial rhizosphere effect. To collect a range of (a)polar chemicals from the system, we developed extraction methods that do not cause detectable damage to root cells or soil-inhabiting microbes, thus preventing contamination with cellular metabolites. Untargeted metabolite profiling by UPLC-Q-TOF mass spectrometry, followed by uni- and multivariate statistical analyses, identified a wide range of secondary metabolites that are enriched in plant-containing soil, compared with control soil without roots. We show that the method is suitable for profiling the rhizosphere chemistry of Zea mays (maize) in agricultural soil, thereby demonstrating the applicability to different plant-soil combinations. Our study provides a robust method for the comprehensive metabolite profiling of non-sterile rhizosphere soil, which represents a technical advance towards the establishment of causal relationships between the chemistry and microbial composition of the rhizosphere

    Nature reserves of the Shire of Wyalkatchem management plan

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    Relativistic many-body calculations of electric-dipole matrix elements, lifetimes and polarizabilities in rubidium

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    Electric-dipole matrix elements for ns-n'p, nd-n'p, and 6d-4f transitions in Rb are calculated using a relativistic all-order method. A third-order calculation is also carried out for these matrix elements to evaluate the importance of the high-order many-body perturbation theory contributions. The all-order matrix elements are used to evaluate lifetimes of ns and np levels with n=6, 7, 8 and nd levels with n=4, 5, 6 for comparison with experiment and to provide benchmark values for these lifetimes. The dynamic polarizabilities are calculated for ns states of rubidium. The resulting lifetime and polarizability values are compared with available theory and experiment.Comment: 8 pages, 2 figure

    Electron transport in gated InGaAs and InAsP quantum well wires in selectively-grown InP ridge structures

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    The purpose of this work is to fabricate ribbon-like InGaAs and InAsP wires embedded in InP ridge structures and investigate their transport properties. The InP ridge structures that contain the wires are selectively grown by chemical beam epitaxy (CBE) on pre-patterned InP substrates. To optimize the growth and micro-fabrication processes for electronic transport, we explore the Ohmic contact resistance, the electron density, and the mobility as a function of the wire width using standard transport and Shubnikov-de Haas measurements. At low temperatures the ridge structures reveal reproducible mesoscopic conductance fluctuations. We also fabricate ridge structures with submicron gate electrodes that exhibit non-leaky gating and good pinch-off characteristics acceptable for device operation. Using such wrap gate electrodes, we demonstrate that the wires can be split to form quantum dots evidenced by Coulomb blockade oscillations in transport measurements.Comment: 5 pages, 4 figures, additional references and improved Fig. 4c, MSS-14 conference, submitted to Physica

    Extending Higher Educational Opportunities through e-Learning: A Case Study from Sri Lanka

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    The Knowledge Economy favours high skilled and adaptable workers, typically those with a degree. Information and Communication Technologies (ICTs) have the potential to extend educational opportunities through e-Learning. In Sri Lanka efforts have been made to employ ICTs in this way. The case study of Orange Valley University (pseudonymous) is presented, exploring the impact of ICT-based distance education on access to higher education. This ethnographic research employed questionnaires, qualitative interviews and documentary analysis. Online learning was found to appeal to a specific segment of the population. Flexibility and prestige were found to be important influences on programme selection. The majority possessed resources and skills for e-Learning; access and quality issues were considered. Globalization is restructuring the ways in which we live, and in a very profound manner (Giddens 2002, p4). This record was migrated from the OpenDepot repository service in June, 2017 before shutting down

    microRNA expression in the aging mouse lung

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    BACKGROUND: MicroRNAs (miRNAs) are a novel class of short double stranded RNA that mediate the post-transcriptional regulation of gene expression. Previous studies have implicated changes in miRNA expression in the regulation of development and the induction of diseases such as cancer. However, although miRNAs have been implicated in the process of aging in C. elegans, nothing is known of their role in mammalian tissues. RESULTS: To address this question, we have used a highly-sensitive, semi-quantitative RT-PCR based approach to measure the expression profile of 256 of the 493 currently identified miRNAs in the lungs from 6 month (adult) and 18 month (aged) old female BALB/c mice. We show that, despite the characteristic changes in anatomy and gene expression associated with lung aging, there were no significant changes in the expression of 256 miRNAs. CONCLUSION: Overall, these results show that miRNA transcription is unchanged during lung aging and suggests that stable expression of miRNAs might instead buffer age related changes in the expression of protein-encoding gene
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