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Selected AbstractsGrid-induced biases in connectivity metric implementations that use regular gridsECOGRAPHY, Issue 3 2010Adam G. Dunn Graph-theoretic connectivity analyses provide opportunities to solve problems related to the management, design and maintenance of fragmented landscapes. However, several modern connectivity metrics are implemented using algorithms that are affected by a grid-induced bias. When paths through a regular grid are calculated, distance errors are introduced into the metric outputs, with patterns based on the shape and orientation of the underlying grid structure. The bias is significant in the proposed implementations of the conditional minimum transit cost method introduced by Pinto and Keitt, and the effective resistance method introduced by McRae, Dickson, Keitt and Shah. One solution for ameliorating the bias that affects regular grids is to use an irregular lattice to represent the landscape. The purpose of this paper is to serve as a timely reminder of the grid-induced bias and to provide a demonstration of the irregular grid as a simple solution to the problem. [source] Error estimation in a stochastic finite element method in electrokineticsINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 11 2010S. Clénet Abstract Input data to a numerical model are not necessarily well known. Uncertainties may exist both in material properties and in the geometry of the device. They can be due, for instance, to ageing or imperfections in the manufacturing process. Input data can be modelled as random variables leading to a stochastic model. In electromagnetism, this leads to solution of a stochastic partial differential equation system. The solution can be approximated by a linear combination of basis functions rising from the tensorial product of the basis functions used to discretize the space (nodal shape function for example) and basis functions used to discretize the random dimension (a polynomial chaos expansion for example). Some methods (SSFEM, collocation) have been proposed in the literature to calculate such approximation. The issue is then how to compare the different approaches in an objective way. One solution is to use an appropriate a posteriori numerical error estimator. In this paper, we present an error estimator based on the constitutive relation error in electrokinetics, which allows the calculation of the distance between an average solution and the unknown exact solution. The method of calculation of the error is detailed in this paper from two solutions that satisfy the two equilibrium equations. In an example, we compare two different approximations (Legendre and Hermite polynomial chaos expansions) for the random dimension using the proposed error estimator. In addition, we show how to choose the appropriate order for the polynomial chaos expansion for the proposed error estimator. Copyright © 2009 John Wiley & Sons, Ltd. [source] Contextualising Craft: Pedagogical Models for Craft EducationINTERNATIONAL JOURNAL OF ART & DESIGN EDUCATION, Issue 3 2009Sinikka Pöllänen Craft education in Finland is, in many aspects, in a state of change. This concerns the independent position of craft as a school subject, the content of the compulsory craft courses containing textiles and technical work, the implementation of the new concept of a holistic craft process in the National Core Curriculum and so on. This bears relevance to the question of how craft should be taught at school. This article explores the ways in which teachers can strengthen the relevance and meaningfulness of craft education at school. Teachers are challenged to provide more authentic instructional contexts and activities beyond the traditional curriculum in order to address successful living in today's society. One solution is to contextualise this teaching with the help of pedagogical models that realise the concept of holistic craft. The pedagogical models discussed in this article are based on curriculum publications, materials in print and research by other scholars. [source] Monitoring and management of the endangered Cape mountain zebra Equus zebra zebra in the Western Cape, South AfricaAFRICAN JOURNAL OF ECOLOGY, Issue 2 2008Rebecca K. Smith Abstract De Hoop Nature Reserve and a neighbouring conservancy contain the most genetically diverse subpopulation of the Endangered (IUCN) Cape mountain zebra (Equus zebra zebra Linnaeus 1758). Although vital for the long-term stability of the meta-population, the population had received limited monitoring post-1999. We summarize data obtained during a population monitoring programme established in 2005. Ninety-nine individuals were identified indicating a decline in annual population growth from 6.6% (1995,1999) to 4.5% (1999,2005). The population was male biased and the deficit of females is likely to have prevented additional breeding herd formation resulting in excess nonbreeding males. These animals are currently of limited reproductive value to the meta-population and may be contributing to the decline in reproductive potential at De Hoop by competing for limited resources. One solution may be to translocate ,excess' males to reinforce existing small populations or establish new populations with females from elsewhere provided that a minimum of 78 animals is maintained at De Hoop to limit genetic loss. Population monitoring and effective management strategies for the De Hoop population and the meta-population are vital to ensure the long-term survival of Cape mountain zebra and for the success of other species recovery programmes. Résumé De Hoop Nature Reserve et une aire de conservation voisine contiennent la sous-population la plus génétiquement variée du zèbre de montagne du Cap (Equus zebra zebra Linnaeus 1758), classé« en danger » par l'UICN. Bien que vitale pour la stabilitéà long terme de la métapopulation, cette population a été peu suivie depuis 1999. Nous avons résumé les données recueillies au cours d'un programme de monitoring de la population instauré en 2005. Quatre-vingt dix-neuf individus ont été identifiés, ce qui indique un déclin de la croissance annuelle de la population de 6,6% (1995,1999) à 4,5% (1999,2005). La population est biaisée en faveur des mâles, et c'est probablement le déficit en femelles qui a empêché la formation d'un troupeau reproducteur supplémentaire, qui a abouti à un excès de mâles nonreproducteurs. Ces animaux sont actuellement de peu de valeur de reproduction pour la métapopulation et pourraient contribuer au déclin du potentiel reproducteur à De Hoop par la compétition qu'ils représentent pour les ressources limitées.Une solution pourrait être de déplacer les mâles « en excès » pour renforcer les petites populations existantes ou pour en établir de nouvelles avec des femelles venues d'ailleurs, pour autant qu'un minimum de 78 animaux restent à De Hoop pour limiter l'appauvrissement génétique. Des stratégies pour le monitoring et la gestion efficace de la population de De Hoop sont vitales pour garantir la survie à long terme du zèbre de montagne du Cap et pour la réussite des programmes de restauration d'autres espèces. [source] rRNA PROBES FOR IDENTIFICATION AND CHARACTERIZATION OF MARINE PHYTOPLANKTON: THEIR POTENTIAL APPLICATION FOR DNA MICROCHIPSJOURNAL OF PHYCOLOGY, Issue 2001Article first published online: 24 SEP 200 Groben R., Lange, M. & Medlin, L. K. Alfred Wegener Institute for Polar and Marine Research, Am Handelshafen 12, D-27570 Bremerhaven, Germany A fast and reliable identification of nano- and picoplankton by light microscopy is often difficult because of the lack of usable morphological characteristics, whereas electron microscopy and biochemical methods are very time consuming. Identification of toxic algae also requires a great deal of taxonomic experrtise so that false positives are not recorded. One solution is to use taxon specific rRNA probes. For this purpose we designed probes for phytoplankton taxa, including toxic algae. These probes were either labelled with Digoxigenin (DIG) and used in DNA dot blot experiments, or labelled with fluorochromes and used in whole-cell hybridisations with fluorescence microscopy or flow cytometric detection. Specific probes could be used over a broad taxonomic range from higher groups (i.e. the class of dinoflagellates) to species level (i.e. Prorocentrum lima). These probes were be used in the EU MAST project AIMS for the development of an automated identification system for marine phytoplankton in combination with flow cytometry and artificial neural networks (ANNs), in the EU MAST DETAL and in the German national project (TEPS) for the development of an early warning system for harmful algal blooms. Results using Digoxigenin (DIG)-labelled probes on picoplankton samples taken from several water bodies indicate that hierarchial re-probing of spotted samples can be achieved and this suggests that probes can be adapted to DNA microchips. Preliminary field results for a hand-held DNA microchip reader are presented. This work was supported by the German BMBF TEPS 03F0161 and the EU AIMS MAS3-CT97-0080 and EU DETAL Q5RS-2000-30778 projects. [source] A species-level phylogenetic supertree of marsupialsJOURNAL OF ZOOLOGY, Issue 1 2004Marcel Cardillo Abstract Comparative studies require information on phylogenetic relationships, but complete species-level phylogenetic trees of large clades are difficult to produce. One solution is to combine algorithmically many small trees into a single, larger supertree. Here we present a virtually complete, species-level phylogeny of the marsupials (Mammalia: Metatheria), built by combining 158 phylogenetic estimates published since 1980, using matrix representation with parsimony. The supertree is well resolved overall (73.7%), although resolution varies across the tree, indicating variation both in the amount of phylogenetic information available for different taxa, and the degree of conflict among phylogenetic estimates. In particular, the supertree shows poor resolution within the American marsupial taxa, reflecting a relative lack of systematic effort compared to the Australasian taxa. There are also important differences in supertrees based on source phylogenies published before 1995 and those published more recently. The supertree can be viewed as a meta-analysis of marsupial phylogenetic studies, and should be useful as a framework for phylogenetically explicit comparative studies of marsupial evolution and ecology. [source] Issues of scale and monitoring status and trends in biodiversityNEW DIRECTIONS FOR EVALUATION, Issue 122 2009Elizabeth T. Kennedy Designing a framework that can generate data to meet multiple audience objectives must consider interactions across levels and multiple scales of interest. One solution is to define targets using global criteria such that units are discrete. This aids identification of the types of data to collect in order to enable aggregation and reporting across relevant scales. By striving to standardize measurable targets and data requirements, we improve our ability to format monitoring information and tailor indicators for different reporting and decision-making purposes. We outline the application of a nested approach presently used by Conservation International and describe some of its advantages and limitations. © Wiley Periodicals, Inc. [source] Object-Oriented Performance ImprovementPERFORMANCE IMPROVEMENT QUARTERLY, Issue 3 2002Ian Douglas ABSTRACT In this paper, a framework to support an object-oriented approach to performance analysis is described. The framework includes the use of collaboration, automation, visual modeling, and reusable repositories of analysis knowledge. The need for a new framework is related to the increasing concern with the cost effectiveness of student and employee development. Efforts to improve the return-on-investment in such development have been hindered by a craft orientation to the design and construction of learning and performance support materials. One solution to this problem has been to enhance the reuse of such materials. Rather than build every new system from scratch in a craft-oriented manner, it is envisioned that systems will be constructed largely of standardized, reusable objects shared through Web-based repositories. Currently, the main focus is on the technological framework necessary for an object-based approach to learning system development. There appears to be little consideration of the changes in analysis and design thinking required for the move towards object-based systems. Such systems should still be required to be directly linked to performance problems and opportunities at both the organizational and individual system levels. [source] Ideas, bargaining and flexible policy communities: policy change and the case of the Oxford Transport StrategyPUBLIC ADMINISTRATION, Issue 3 2003Geoffrey DudleyArticle first published online: 8 AUG 200 Critiques of policy networks have highlighted particularly the inability of concepts such as policy communities to explain policy change. The established construction of policy community places it chiefly as a metaphor for a relatively stable network within the policy process, which emphasizes the resource dependencies between key stakeholders. Typically, a process of bargaining brings about accommodation and a state of negotiated order. However, a key problem arises in explaining major policy change where an established policy community persists. One solution here is to appreciate that, over time, dominant ideas and associated policy meanings may shift appreciably within an otherwise durable policy community. Thus, even a seemingly insulated policy community, under certain conditions, may not be immune to idea mutation and new policy meanings. Given the central importance of policy communities, these shifts may induce significant policy change. A case study of this type is provided by the Oxford Transport Strategy (OTS), where a dual process of change took place. On one level of analysis, a challenge to the policy community produced a typical bargaining strategy, with an emphasis on negotiated order. On another level of analysis, however, the terms of the policy debate shifted markedly, and produced a new meaning for the key concept of integrated transport within the policy community. In turn, this process induced significant policy change. The article concludes that, ironically, the survival of a policy community depends on its ability to re-create itself by visualizing a new future. [source] Student attitudes to surgical teaching in provincial hospitalsAUSTRALIAN JOURNAL OF RURAL HEALTH, Issue 3 2003Martin H. Bruening ABSTRACT Objective:The ever-increasing pressure on metropolitan teaching hospitals to rationalise budgets and increase productivity has resulted in a dwindling amount of teaching opportunity for the medical student population. One solution to the problem was to utilise a largely untapped resource in South Australia, namely the provincial hospitals, however, student opinion regarding such a radical change had yet to be determined. Design:A questionnaire was circulated among an entire year group of medical students who would be undertaking the revised surgical curriculum with rural attachments. Setting:In October 1997, a decision was made by the Department of Surgery at the University of Adelaide to proceed with optional rural surgical attachments in 1998. Subjects:The survey was distributed to the 125 members of the 1997 fifth year medical student group. Results:A total of 92 questionnaires were returned giving a response rate of 75%. Thirty-nine students ranked a rural term in their top half of preferences, while a further 18 indicated that they would go to a rural centre if they had to. Conclusion:Despite having little warning of the impending changes to their surgical curriculum, the majority of students who responded to the questionnaire stated that they would be willing to venture to the country locations. Before planning significant changes to an established curriculum, the student group should be consulted to gauge their opinion. What is already known:Within the medical literature, studies have been performed with regard to student opinions regarding postgraduate internships in rural locations, but to our knowledge, this survey represents the first study into student opinion with particular reference to rural surgical attachments prior to their commencement within a medical school curriculum. What this study adds:As a result of this study, it can now be concluded that a considerable amount of interest exists within the student population to undertake rural surgical rotations. [source] Substrate-permeable encapsulation of enzymes maintains effective activity, stabilizes against denaturation, and protects against proteolytic degradationBIOTECHNOLOGY & BIOENGINEERING, Issue 5 2001Mathieu Nasseau Abstract How can enzymes be protected against denaturation and proteolysis while keeping them in a fully functional state? One solution is to encapsulate the enzymes into liposomes, which enhances their stability against denaturation and proteases. However, the permeability barrier of the lipid membrane drastically reduces the activity of enzyme entrapped in the liposome by reducing the internal concentration of the substrate. To overcome this problem, we permeabilized the wall of the liposome by reconstitution of a porin from Escherichia coli. In this way, we recovered the full functionality of the enzyme while retaining the protection against denaturation and proteolytic enzymes. © 2001 John Wiley & Sons, Inc. Biotechnol Bioeng 75: 615,618, 2001. [source] Satellite Remote Sensing as a Tool in Lahar Disaster ManagementDISASTERS, Issue 2 2002Norman Kerle At least 40,000 deaths have been attributed to historic lahars (volcanic mudflows). The most recent lahar disaster occurred in 1998 at Casita volcano, Nicaragua, claiming over 2,500 lives. Lahars can cover large areas and be highly destructive, and constitute a challenge for disaster management. With infrastructure affected and access frequently impeded, disaster management can benefit from the synoptic coverage provided by satellite imagery. This potential has been recognised for other types of natural disasters, but limitations are also known. Dedicated satellite constellations for disaster response and management have been proposed as one solution. Here we investigate the utility of currently available and forthcoming optical and radar sensors as tools in lahar disaster management. Applied to the Casita case, we find that imagery available at the time could not have significantly improved disaster response. However, forthcoming satellites, especially radar, will improve the situation, reducing the benefit of dedicated constellations. [source] Transport and environment: policy directions for europeENVIRONMENTAL POLICY AND GOVERNANCE, Issue 3 2001Robert Tinch Transport externalities are among the most important environmental problems affecting quality of life in Europe. Forecasts suggest that past environmental improvements may now be rolled back by traffic growth, and current traffic trends are not sustainable. The theory of environmental policy proposes pricing external costs at their marginal social costs as one solution. Although full marginal social cost pricing is impracticable, advances in tolling technology and environmental valuation mean that it is now a viable option to approximate such charging. There are signs that the European Commission and other bodies are starting to favour pricing over regulatory instruments. However, often overlooked is the potential for non-convexities in the transport sector or between transport and the rest of the economy. For example it may be that small increases in resources for public transport would not result in welfare gains, whereas large increases would. Non-convexities would mean that market forces under marginal social cost pricing might lead away from the optimal transport system. This is one reason why pricing instruments cannot in themselves be a panacea for transport externalities or bring about a sustainable transport system. Copyright © 2001 John Wiley & Sons, Ltd and ERP Environment [source] Milestones in ecological thought , A canon for plant ecologyJOURNAL OF VEGETATION SCIENCE, Issue 2 2005Paul A. Keddy Abstract. Scientific progress in plant ecology is at risk of being obscured by increasing ignorance of major works in the field. The driving force seems to be the twin seductions of novelty and crowd psychology. I illustrate this tendency with three examples from plant community ecology that span the past thirty years of ecological research. I offer, as one solution, the concept of a canon: a short list of essential books that we assume all students and co-workers have read, a short list that summarizes the wisdom of the discipline. A canon can be likened to DNA, be it in music, art, or science, as it carries forward through time the key ideas that have worked in the past. Without a canon, there is no memory of past achievement, no context for appreciating current work, and no way of judging the quality of newer productions. I suggest 20 essential books (the short canon), and 22 complementary readings, for a total of 42 books needed in any young professional's library on plant ecology. [source] Planar slot antenna with PBG filter for wireless communicationsMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 3 2007Fabrizio Consoli Abstract A planar circular slot antenna, integrated with a band-stop photonic bandgap filter is presented here. The complete realized prototype is suitable to cover the bandwidth requirements of many wireless communication standards in one solution. The work describes the detailed study of both the antenna and the PBG filter properties. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 551,555, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22191 [source] Programmed motion in the presence of homogeneityASTRONOMISCHE NACHRICHTEN, Issue 8 2009G. Bozis Abstract In the framework of the inverse problem of dynamics, we face the following question with reference to the motion of one material point: Given a region Torb of the xy plane, described by the inequality g (x, y) , c0, are there potentials V = V (x, y) which can produce monoparametric families of orbits f (x, y) = c (also to be found) lying exclusively in the region Torb? As the relevant PDEs are nonlinear, an answer to this question (generally affirmative, but not with assurance) can be given by the procedure of the determination of certain constants specifying the pertinent functions. In this paper we ease the mathematics involved by making certain simplifying assumptions referring to the homogeneity of both the function g (x, y) (describing the boundary of Torb) and of the slope function ,(x, y) = fy/fx (representing the required family f (x, y) = c). We develop the method to treat the so formulated problem and we show that, even under these restrictive assumptions, an affirmative answer is guaranteed provided that two algebraic equations have in common at least one solution (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Second-order backward stochastic differential equations and fully nonlinear parabolic PDEsCOMMUNICATIONS ON PURE & APPLIED MATHEMATICS, Issue 7 2007Patrick Cheridito For a d -dimensional diffusion of the form dXt = ,(Xt)dt + ,(Xt)dWt and continuous functions f and g, we study the existence and uniqueness of adapted processes Y, Z, ,, and A solving the second-order backward stochastic differential equation (2BSDE) If the associated PDE has a sufficiently regular solution, then it follows directly from Itô's formula that the processes solve the 2BSDE, where ,, is the Dynkin operator of X without the drift term. The main result of the paper shows that if f is Lipschitz in Y as well as decreasing in , and the PDE satisfies a comparison principle as in the theory of viscosity solutions, then the existence of a solution (Y, Z,,, A) to the 2BSDE implies that the associated PDE has a unique continuous viscosity solution v and the process Y is of the form Yt = v(t, Xt), t , [0, T]. In particular, the 2BSDE has at most one solution. This provides a stochastic representation for solutions of fully nonlinear parabolic PDEs. As a consequence, the numerical treatment of such PDEs can now be approached by Monte Carlo methods. © 2006 Wiley Periodicals, Inc. [source] | ||||||||||||||||||||||