3,132 research outputs found
Coronas for properly combable spaces
No full textThis paper is a systematic approach to the construction of coronas (i.e. Higson dominated boundaries at infinity) of combable spaces. We introduce three additional properties for combings: properness, coherence and expandingness. Properness is the condition under which our construction of the corona works. Under the assumption of coherence and expandingness, attaching our corona to a Rips complex construction yields a contractible [Formula: see text]-compact space in which the corona sits as a [Formula: see text]-set. This results in bijectivity of transgression maps, injectivity of the coarse assembly map and surjectivity of the coarse co-assembly map. For groups we get an estimate on the cohomological dimension of the corona in terms of the asymptotic dimension. Furthermore, if the group admits a finite model for its classifying space [Formula: see text], then our constructions yield a [Formula: see text]-structure for the group
Slant products on the Higson–Roe exact sequence
No full textWe construct a slant product /: S-p(X x Y) x K1-q (c(red)Y) -> Sp-q(X) on the analytic structure group of Higson and Roe and the K-theory of the stable Higson corona of Emerson and Meyer. The latter is the domain of the co-assembly map mu* : K1-* (c(red)Y) -> K* (Y). We obtain such products on the entire Higson-Roe sequence. They imply injectivity results for external product maps. Our results apply to products with aspherical manifolds whose fundamental groups admit coarse embeddings into Hilbert space. To conceptualize the class of manifolds where this method applies, we say that a complete spine-manifold is Higson-essential if its fundamental class is detected by the co-assembly map. We prove that coarsely hypereuclidean manifolds are Higson-essential. We draw conclusions for positive scalar curvature metrics on product spaces, particularly on non-compact manifolds. We also obtain equivariant versions of our constructions and discuss related problems of exactness and amenability of the stable Higson corona
The theory and estimation of Engel curves: some estimates for meat in New Zealand
No full textThis paper is one of a series based on
original research conducted by Christopher Yandle at Lincoln on the New Zealand Meat Market. In the course of this
work the author conducted a questionaire survey of 300
families in Christchurch in which heads of families
were asked to indicate their basic preferences for
different meats, and to record their actual expenditure
on meat along with family income for a given week. This paper deals at a more technical level with the analysis of this
data in particular with the derivative of Engel Curves
showing the relationship between consumers incomes and their purchases of meat. The subject is the estimation of Engel curves from survey data. A review is made of the appropriate economic theory,
and the application of that theory to market generated data
Notes on family-group names for bees (Hymenoptera: Apoidea)
No full textAbstract. Corrected authorships and dates are provided for four family-group names for bees based on previously unrecognized earlier usages that made them nomenclatorially available. Sagemehl is newly recognized as the author of family-group names based on Dasypoda Latreille (Melittidae: Dasypodainae), Macropis Panzer (Melittidae: Macropidinae), and Hylaeus Fabricius (Colletidae: Hylaeinae), and Kawall as the author the family-group name based on Melitta Kirby, thereby taking precedence over the subsequent use of similar names by Börner, Robertson, Vi-ereck, and Schenck, respectively. In addition, descriptions are provided for three new family-group taxa; Dieunomiini Engel, new tribe (Halictidae: Nomiinae), Eremaphantina Engel, new subtribe (Melittidae: Hesperapini), and Tarsaliini Engel, new tribe (Apidae: Apinae); and one new genus-group taxon, Eremaphantella Engel, new subgenus
Facilitating innovation : an action-oriented approach and participatory methodology to improve innovative social practice in agriculture
No full textThis study focuses upon the social organization of innovation. It makes use of insights from knowledge and information systems research, development sociology, management science and applied philosophy and seeks answers to the following questions: What do social actors, individuals and/or organizations, actually do to innovate their practices? How do they organize themselves? Can this be managed or facilitated, and if so, how? The research is exploratory rather than conclusion-oriented and synthesizes the results of over 50 case studies of agricultural innovation in 15 different countries, including the Netherlands. Its main results are a conceptualization of innovation as a social process and a participatory action-research methodology to enhance innovative performance. The methodology is based on soft systems thinking and offers a variety of 'windows' or analytical perspectives to help social actors analyze the way they are organized for innovation in an action-oriented fashion. The methodology has been field-tested in 15 areas in 7 different countries.The author proposes that agricultural innovation can be looked at as resulting from the interplay between social actors representing relevant social practices. Social practices relevant to agricultural innovation include farming, research, extension, education, agroindustrial processing, marketing, mass media communication, policy-making, product quality control and the development, production, certification and distribution of inputs. Innovation then is a diffuse, social process of both individual and collective inquiry into intentions, alternative solutions and enabling and constraining conditions which leads to new or modified problem definitions and practical choices of solutions. The organization and quality of these inquiries eventually determine innovative performance at a certain point in time. What social actors actually do to innovate their practices can be understood as networking: social actors in search of relevant ideas, knowledge, information and experiences, continuously build and manage relationships with others which, by some standard, they consider relevant to innovating their practices. As a result of networking, over time forms of social organization of innovation emerge. These reflect dynamics of their own and are not fully describable or explicable in terms of micro-events.The author proposes four such emergent forms to be relevant to students of complex innovation theatres: Convergences emerge when social actors narrow down the scope of their arguments and the range of issues and alternative scenarios they consider relevant to innovating their practices. Resource coalitions emerge when social actors decide to pool their resources in a joint performance. Communication networks emerge as a direct consequence of social actors' decisions to create joint learning opportunities and to produce and exchange information among themselves. Over time, where the above forms coincide, a pattern of more or less durable relationships between a limited set of social actors, an innovation configuration, may emerge. In such a configuration strategic consensus, a clear definition of tasks and responsibilities and a rational allocation of resources among social actors is possible. It also appears that each of these forms, but particularly the last one, may demonstrate inertia when faced with rapidly changing demands and/or circumstances. As a result, innovative performance may drop.To enable social actors to assess their current way of organizing for innovation, a participatory action-research methodology is proposed: RAAKS, Rapid or Relaxed Appraisal of Agricultural Knowledge Systems. Its design is based upon 'soft knowledge systems thinking', combining the philosophy and guiding principles of soft systems methodology with analytical instruments from knowledge systems research. Through active participation of relevant social actors, RAAKS aims at a threefold objective: to raise awareness and understanding, to probe new alliances and to formulate proposals for action. It guides participants through an accumulative, interactive learning process leading from problem appraisal, via a joint inquiry towards the definition of potentially useful actions and/or interventions. In recognition of the appreciative character of innovation and its social organization, RAAKS offers a choice of perspectives or 'windows' to help stakeholders recognize, organize and debate relevant ideas and events. The conceptual approach mentioned above supports the integration of the findings into a more comprehensive understanding of the social organization of innovation in each particular case.RAAKS has been field-tested over a dozen times in the Netherlands and in six countries in Central America. These experiences confirmed its relevance and applicability as a methodology, as well as its adaptability to particular demands and circumstances. RAAKS proved most useful in situations where, often ill-defined, feelings of unease persist among relevant stakeholders about the course innovation takes or its pace. It has proved useful in training (future) extension and research managers, and helping them to understand the context in which they operate. RAAKS also demonstrated its usefulness to those organizations or individuals who sell or provide 'knowledge/information intensive' products or services, such as research, extension and advisory services. It provides them with an instrument to appreciate the dynamic social context in which their products or services have to be marketed and are to prove themselves. Finally, due to its participatory character and soft systems design, RAAKS seems a promising instrument to help social actors organize themselves to deal with complex societal problems, which require higher levels of effective cooperation among stakeholders, such as natural resource management, regional development, stopping environmental degradation or waste disposal. Several experiences with RAAKS outside agriculture illustrate that its relevance to facilitating complex innovation processes is not limited to agricultural development as such.As a general conclusion, the study points at the need to amplify research on knowledge management. To facilitate knowing between agencies and organizations, interorganizational communication, whether direct or indirect, joint learning, sense making and resource pooling would have to become objects of study and eventually of (knowledge) management. Also, networking would have to be studied, its adequacy, effectiveness and efficiency in specific situations assessed and improvements designed and evaluated. The author argues that the challenge for management sciences with respect to social organization of innovation is to achieve a balance between direction and control on the one hand, and the creation and maintenance of space for serendipitous and epiphenomenal improvements on the other. In addition, he proposes RAAKS may contribute not only to facilitating innovative social practice directly, but to scientific inquiry as well. For such a purpose, its potential and limitations do need to be further evaluated. In general, he suggests, soft (knowledge) systems thinking receives far less attention from the research community than it deserves
Clinonana rafaeli Engel et Takiya, sp. nov.
No full textClinonana rafaeli Engel et Takiya sp. nov. (Figs. 1 D, 6) Measurements in mm (ɗ holotype). Total length: 16.0. Crown median length: 1.1. Pronotum median length: 2.5. Pronotum largest width: 7.2. Mesonotum largest width: 4.0. Mesonotum median length: 4.3. External morphology. Crown (Figs. 1 D, 6 A) median length three-tenths of interocular (ratio= 0.34) and transocular width (ratio= 0.26). Pronotum (Figs. 1 D, 6 A) largest width 2.9 times median length; largest width 1.8 times largest mesonotum visible width. Mesonotum (Figs. 1 D, 6 A) length 1.2 times longer than combined mesal length of crown and pronotum. Other characteristics as in generic description. Male genitalia. Styles (Figs. 6 D, E) in lateral view with median concavity on ventral margin. Aedeagus (Figs. 6 G, H) shaft preatrium pair of processes extending only until two-thirds of shaft length. Female unknown. Notes. Clinonana rafaeli sp. nov. is very similar to C. mirabilis in external morphology and male genitalia. Both species are smaller and have a less laterally expanded pronotum (Figs. 1 C, D, 4 A, 6 A) than C. impensa (Figs. 1 B, 3 A). The new species differs from C. mirabilis by the following male genital characters: style in lateral view with ventral concavity in median portion (Fig. 6 E, arrow); and aedeagal shaft thinner than in C. mirabilis, with preatrium basal processes extending only two-thirds length of shaft (Figs. 6 G, H). In C. mirabilis the basal processes reach the apex of the aedeagus shaft. Etymology. The new species epithet is in honor of the dipterist Dr. José Albertino Rafael (INPA), who coordinated projects including field work in the Brazilian Amazon which made possible the collection of specimens of Clinonana and many other leafhoppers by the junior author, besides being responsible for the collection of about half of specimens studied herein. Material examined. Holotype, Brazil: Rondônia: ɗ, Porto Velho, Campus UNIR, 8 ° 50 ' 4 " S 63 ° 56 ' 35 " W, 17 IV 2006 (F. F. Xavier & J. A. Rafael), (INPA).Published as part of Engel, Giulia & Takiya, Daniela Maeda, 2012, Synopsis of Clinonana Osborn (Hemiptera: Cicadellidae: Iassinae): new distributional records and description of a new species, pp. 19-30 in Zootaxa 3329 on pages 26-28, DOI: 10.5281/zenodo.28122
Simultaneous [18F]fluoride and gadobutrol enhanced coronary positron emission tomography/magnetic resonance imaging for in vivo plaque characterization
No full textAbstract
Aims
18F-sodium fluoride ([18F]fluoride) and gadobutrol are promising probes for positron emission tomography (PET) and magnetic resonance imaging (MRI) characterizing coronary artery disease (CAD) activity. Unlike [18F]fluoride-PET/computed tomography (CT), the potential of PET/MR using [18F]fluoride and gadobutrol simultaneously, has so far not been evaluated. This study assessed feasibility and diagnostic potential of [18F]fluoride and gadobutrol enhanced dual-probe PET/MR in patients with CAD.
Methods and results
Twenty-one patients (age, 66.7 ± 6.7 years) with CAD scheduled for invasive coronary angiography (XCA) underwent simultaneous [18F]fluoride (mean activity/effective dose: 157.2 ± 29.7 MBq/3.77 ± 0.72 mSv) and gadobutrol enhanced PET/MR on an integrated PET/MRI (3 T) scanner. Optical coherence tomography (OCT) was used as reference. Target-to-background ratio (TBR, [18F]fluoride-PET) and contrast-to-noise ratio (CNR) values (MRI, gadobutrol) were calculated for each coronary segment. Previously suggested PET/CT-TBR thresholds for adverse coronary events were evaluated. High-risk plaques, i.e. calcified and non-calcified thin-cap fibroatheromas (TCFAs) were predominantly located in segments with a TBR >1.28 (P = 0.012). Plaques containing a lipid core on OCT, were more frequently detected in segments with a TBR >1.25 (P < 0.001). TBR values significantly correlated with maximum calcification thickness (P = 0.009), while fibrous cap thickness was significantly less in segments with a TBR >1.28 (P = 0.044). Above a TBR threshold of >1.28, CNR values significantly correlated with the presence of calcified TCFAs (P = 0.032).
Conclusion
Simultaneous [18F]fluoride and gadobutrol dual-probe PET/MRI is feasible in clinical practice and may facilitate the identification of high-risk patients. The combination of coronary MR-derived CNR values post gadobutrol and [18F]fluoride based TBR values may improve identification of high-risk plaque features
On the strong connectivity of the 2-Engel graphs of almost simple groups
No full textThe Engel graph of a finite group is a directed graph encoding the pairs
of elements in satisfying some Engel word. Recent work of Lucchini and the
third author shows that, except for a few well-understood cases, the Engel
graphs of almost simple groups are strongly connected. In this paper, we give a
refinement to this analysis
GPU Pro 4: advanced rendering techniques
No full textGPU Pro4: Advanced Rendering Techniques presents ready-to-use ideas and procedures that can help solve many of your day-to-day graphics programming challenges. Focusing on interactive media and games, the book covers up-to-date methods producing real-time graphics. Section editors Wolfgang Engel, Christopher Oat, Carsten Dachsbacher, Michal Valient, Wessam Bahnassi, and Sebastien St-Laurent have once again assembled a high-quality collection of cutting-edge techniques for advanced graphics processing unit (GPU) programming. Divided into six sections, the book begins with discussions on the ab
GPU PRO 3: Advanced rendering techniques
No full textGPU Pro3, the third volume in the GPU Pro book series, offers practical tips and techniques for creating real-time graphics that are useful to beginners and seasoned game and graphics programmers alike. Section editors Wolfgang Engel, Christopher Oat, Carsten Dachsbacher, Wessam Bahnassi, and Sebastien St-Laurent have once again brought together a high-quality collection of cutting-edge techniques for advanced GPU programming. With contributions by more than 50 experts, GPU Pro3: Advanced Rendering Techniques covers battle-tested tips and tricks for creating interesting geometry, realistic sh
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