174 research outputs found

    Evaluating Land Management Options (ELMO): a participatory tool for assessing farmers’ sustainable land management decision preferences and trade-offs

    Get PDF
    This document provides guidance on applying the ELMO tool. It is primarily targeted at researchers seeking to collect information about the social and economic drivers of land use decisions, and wishing to investigate farmers’ sustainable land management preferences and trade-offs. As illustrated on the facing page, ELMO is organised around three basic questions, and entails 10 steps. Although these steps follow a logical, iterative process, it should be emphasised that the tool can be modified and adapted to the specific needs and context within which it is being applied. It is not always necessary to apply each and every step

    Agent-based modelling and construction – reconstructing antiquity’s largest infrastructure project

    Get PDF
    Archaeological remains around the world are testament that large-scale construction projects have been successfully carried out for millennia. This success is particularly evident through the great infrastructural works of the Roman Empire. Yet, it was when the capital was moved from Rome to Constantinople that the largest of these projects was undertaken. This megaproject of the fourth- and fifth-century water supply was made of hundreds of kilometres aqueduct channels and bridges that brought fresh water to the city’s complex system of reservoirs and cisterns. Unlike projects of the previous centuries, we are left with no written record of how this titanic project was undertaken and existing archaeological and historical commentaries on structures of this period do not provide details of organization of construction. We explore the nature of building Constantinople’s water supply through diverse sources of knowledge and the application of agent-based modelling – a method for simulating the actions, interactions and behaviours of autonomous agents and the resulting emergent properties of the system in which they are a part. This paper demonstrates the ability of ABM to develop and test richer hypotheses about historical construction organization and management than physical and historical evidence on their own

    Least-squares methods with Poissonian noise: an analysis and a comparison with the Richardson-Lucy algorithm

    Full text link
    It is well-known that the noise associated with the collection of an astronomical image by a CCD camera is, in large part, Poissonian. One would expect, therefore, that computational approaches that incorporate this a priori information will be more effective than those that do not. The Richardson-Lucy (RL) algorithm, for example, can be viewed as a maximum-likelihood (ML) method for image deblurring when the data noise is assumed to be Poissonian. Least-squares (LS) approaches, on the other hand, arises from the assumption that the noise is Gaussian with fixed variance across pixels, which is rarely accurate. Given this, it is surprising that in many cases results obtained using LS techniques are relatively insensitive to whether the noise is Poissonian or Gaussian. Furthermore, in the presence of Poisson noise, results obtained using LS techniques are often comparable with those obtained by the RL algorithm. We seek an explanation of these phenomena via an examination of the regularization properties of particular LS algorithms. In addition, a careful analysis of the RL algorithm yields an explanation as to why it is more effective than LS approaches for star-like objects, and why it provides similar reconstructions for extended objects. We finish with a convergence analysis of the RL algorithm. Numerical results are presented throughout the paper. It is important to stress that the subject treated in this paper is not academic. In fact, in comparison with many ML algorithms, the LS algorithms are much easier to use and to implement, often provide faster convergence rates, and are much more flexible regarding the incorporation of constraints on the solution. Consequently, if little to no improvement is gained in the use of an ML approach over an LS algorithm, the latter will often be the preferred approach.Comment: High resolution images are available upon request. submitted to A&

    Phyllodes Tumor vs Fibroadenoma: Diagnosis and Management

    Get PDF
    Case: The patient is a 71 year-old woman who presented with enlarging painful breast mass. She had history of previous excision of a fibroadenoma in her left breast in 1993. She underwent menopause at 52 and does not take estrogen. Diagnostic imaging revealed 4.7cm breast mass, which had increased from prior measurement of 2.8cm to 4.7cm. Core biopsy demonstrated a fibroepithelial neoplasm areas of hypercellular stroma and occasional stromal mitotic figures most consistent with phyllodes tumor. Lumpectomy was performed. Final pathology showed a 4.8cm well-demarcated tumor with mildly pleomorphic spindled cells in the stroma and up to 1 per 10 mitoses per high powered field, consistent with benign phyllodes. The patient was followed every 6 months with imaging for 2 years without recurrence. Conclusions: Phyllodes tumors are rare fibroepithelial tumors of varying metastatic potential that can be mistaken for benign fibroadenomas. Phyllodes tumors should be surgically excised with wide margins, needing radiation or chemotherapy only if recurrent or large (>10cm), whereas fibroadenomas can be managed expectantly if asymptomatic (Gnerlich, 2014). Phyllodes tumors are often diagnosed in women ages 35-55. The patient in this case was diagnosed at a more advanced age with benign disease, although older age is more often associated with increased histologic grade (Mishra, 2013) (Karim, 2009). Borderline and malignant tumors are more likely to recur within two years of resection; there is less data on recurrence rates of benign tumors. Clinical Significance: Phyllodes tumors should be suspected with rapid growth of a known fibroadenoma. Core biopsy should be performed rather than fine needle aspiration for accurate diagnosis. Although phyllodes tumors comprise less than 1% of all breast neoplasms, it is crucial that uncommon pathologies are diagnosed correctly so that patients receive appropriate treatment

    Ringing effects reduction by improved deconvolution algorithm Application to A370 CFHT image of gravitational arcs

    Get PDF
    We develop a self-consistent automatic procedure to restore informations from astronomical observations. It relies on both a new deconvolution algorithm called LBCA (Lower Bound Constraint Algorithm) and the use of the Wiener filter. In order to explore its scientific potential for strong and weak gravitational lensing, we process a CFHT image of the galaxies cluster Abell 370 which exhibits spectacular strong gravitational lensing effects. A high quality restoration is here of particular interest to map the dark matter within the cluster. We show that the LBCA turns out specially efficient to reduce ringing effects introduced by classical deconvolution algorithms in images with a high background. The method allows us to make a blind detection of the radial arc and to recover morphological properties similar to thoseobserved from HST data. We also show that the Wiener filter is suitable to stop the iterative process before noise amplification, using only the unrestored data.Comment: A&A in press 9 pages 9 figure

    Open Access Week Interview with Martin Paul Eve

    Get PDF
    An interview for OA week 202

    Survey to assess farmers’ economic perceptions, preferences and decision-making criteria relating to climate-smart soil protection & rehabilitation in Benin, Burkina Faso, Ethiopia, India and Kenya

    Get PDF
    Key findings This document reports on a study to assess farmers’ economic perceptions, preferences and decision-making criteria relating climate-smart soil protection and rehabilitation (CSS) measures in Benin, Burkina Faso, Ethiopia, India and Kenya. Specifically, it aims to answer the question: what do farmers perceive as the key costs, benefits, barriers and enabling conditions that influence their uptake (or rejection) of different land management practices? The study applies the Evaluating Land Management Options (ELMO) tool, a participatory method that has been developed by CIAT to investigate farmers’ own perceptions and explanations of the advantages, disadvantages and trade-offs associated with different land management choices as they relate to their needs, aspirations, opportunities and constraints. The study is able to highlight farmers’ preferences for different CSS measures in the five study sites, as well as to identify the main inputs, outcomes, barriers and enabling conditions that influence their uptake (or rejection) of different land management practices. While there remain key differences between (and within) the study sites, a number of common lessons emerge which relate to the assessment and design of CSS measures. One is the need to take account of farmers’ constraints and limitations as concerns their ability to access the cash, labour and technical knowhow that are required to implement new land management practices. Even when a land management technique may be perceived to be of great interest and high potential benefit, many farmers are simply not in a position to allocate the extra inputs that are required to implement it. The other is to recognise that most farmers do not merely strive to achieve one outcome or maximise a single stream of benefits when they make land management choices. Rather, it is the array of values, and the interactions between them, that matter and shape their preferences. The most desirable and viable land management alternatives are seen to be those which not only increase the flow of physical products (for example cash, food and other items), but also enhance livelihood diversity and security (such as filling critical food and cash gaps over the course of the year), at the same time as helping to secure longer-term improvements in the production base (most importantly soil fertility and moisture). The study findings serve to underline the fact that the most preferred land management are not necessarily those that yield the highest production gains, generate the greatest income, or entail the lowest costs (the characteristics that would traditionally be deemed important when land management interventions are designed). The metrics that are used to determine the desirability and viability of different land management options, measure their desired effects, and weigh up their advantages and disadvantages do not just concern cash costs and benefits or physical inputs and outputs, but encompass a wide array of monetary and non-monetary factors (such as the type and diversity of benefits generated and costs incurred, their timing, certainty, risk and relative ease of delivery). Unless these broader needs, constraints and preferences are identified, and addressed in the land management ‘solutions’ that are presented to farmers, CSS measures are unlikely to be acceptable, effective or sustainable in practice

    Galaxy Zoo: morphological classification of galaxy images from the Illustris simulation

    Get PDF
    Modern large-scale cosmological simulations model the universe with increasing sophistication and at higher spatial and temporal resolutions. These ongoing enhancements permit increasingly detailed comparisons between the simulation outputs and real observational data. Recent projects such as Illustris are capable of producing simulated images that are designed to be comparable to those obtained from local surveys. This paper tests the degree to which Illustris achieves this goal across a diverse population of galaxies using visual morphologies derived from Galaxy Zoo citizen scientists. Morphological classifications provided by these volunteers for simulated galaxies are compared with similar data for a compatible sample of images drawn from the Sloan Digital Sky Survey (SDSS) Legacy Survey. This paper investigates how simple morphological characterization by human volunteers asked to distinguish smooth from featured systems differs between simulated and real galaxy images. Significant differences are identified, which are most likely due to the limited resolution of the simulation, but which could be revealing real differences in the dynamical evolution of populations of galaxies in the real and model universes. Specifically, for stellar masses, a substantially larger proportion of Illustris galaxies that exhibit disk-like morphology or visible substructure, relative to their SDSS counterparts. Toward higher masses, the visual morphologies for simulated and observed galaxies converge and exhibit similar distributions. The stellar mass threshold indicated by this divergent behavior confirms recent works using parametric measures of morphology from Illustris simulated images. When , the Illustris data set contains substantially fewer galaxies that classifiers regard as unambiguously featured. In combination, these results suggest that comparison between the detailed properties of observed and simulated galaxies, even when limited to reasonably massive systems, may be misleading

    Volunteering and well-being : do self-esteem, optimism, and perceived control mediate the relationship?

    Full text link
    Volunteers play a vital role in modern societies by boosting the labor force within both the public and private sectors. While the factors that may lead people to volunteer have been investigated in a number of studies, the means by which volunteering contributes to the well-being of such volunteers is poorly understood. It has been suggested through studies that focus on the absence of depression in volunteers that self-esteem and sense of control may be major determinants of the increased well-being reported by volunteers. This is consistent with the homeostatic model of subjective well-being, which proposes that self-esteem, optimism, and perceived control act as buffers that mediate the relationship between environmental experience and subjective well-being (SWB). Using personal well-being as a more positive measure of well-being than absence of depression, this study further explored the possible mediating role of self-esteem, optimism, and perceived control in the relationship between volunteer status and well-being. Participants (N = 1,219) completed a 97-item survey as part of the Australian Unity Wellbeing project. Variables measured included personal well-being, self-esteem, optimism, and a number of personality and psychological adjustment factors. Analyses revealed that perceived control and optimism, but not self-esteem, mediated the relationship between volunteer status and personal well-being.<br /

    Controlling crystallization and its absence: Proteins, colloids and patchy models

    Full text link
    The ability to control the crystallization behaviour (including its absence) of particles, be they biomolecules such as globular proteins, inorganic colloids, nanoparticles, or metal atoms in an alloy, is of both fundamental and technological importance. Much can be learnt from the exquisite control that biological systems exert over the behaviour of proteins, where protein crystallization and aggregation are generally suppressed, but where in particular instances complex crystalline assemblies can be formed that have a functional purpose. We also explore the insights that can be obtained from computational modelling, focussing on the subtle interplay between the interparticle interactions, the preferred local order and the resulting crystallization kinetics. In particular, we highlight the role played by ``frustration'', where there is an incompatibility between the preferred local order and the global crystalline order, using examples from atomic glass formers and model anisotropic particles.Comment: 11 pages, 7 figure
    • 

    corecore