Academic literature on the topic '2-category theory'
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Journal articles on the topic "2-category theory"
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Bourke, John. "Accessible aspects of 2-category theory." Journal of Pure and Applied Algebra 225, no. 3 (March 2021): 106519. http://dx.doi.org/10.1016/j.jpaa.2020.106519.
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Bourke, John. "Skew structures in 2-category theory and homotopy theory." Journal of Homotopy and Related Structures 12, no. 1 (December 8, 2015): 31–81. http://dx.doi.org/10.1007/s40062-015-0121-z.
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Riehl, Emily, and Dominic Verity. "The 2-category theory of quasi-categories." Advances in Mathematics 280 (August 2015): 549–642. http://dx.doi.org/10.1016/j.aim.2015.04.021.
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del Hoyo, Matias L. "On the loop space of a 2-category." Journal of Pure and Applied Algebra 216, no. 1 (January 2012): 28–40. http://dx.doi.org/10.1016/j.jpaa.2011.05.001.
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Elgueta, Josep. "2-Cosemisimplicial objects in a 2-category, permutohedra and deformations of pseudofunctors." Journal of Pure and Applied Algebra 191, no. 3 (August 2004): 223–64. http://dx.doi.org/10.1016/j.jpaa.2003.12.007.
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Piacenza, Robert J. "Homotopy Theory of Diagrams and CW-Complexes Over a Category." Canadian Journal of Mathematics 43, no. 4 (August 1, 1991): 814–24. http://dx.doi.org/10.4153/cjm-1991-046-3.
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The purpose of this paper is to introduce the notion of a CW complex over a topological category. The main theorem of this paper gives an equivalence between the homotopy theory of diagrams of spaces based on a topological category and the homotopy theory of CW complexes over the same base category.A brief description of the paper goes as follows: in Section 1 we introduce the homotopy category of diagrams of spaces based on a fixed topological category. In Section 2 homotopy groups for diagrams are defined. These are used to define the concept of weak equivalence and J-n equivalence that generalize the classical definition. In Section 3 we adapt the classical theory of CW complexes to develop a cellular theory for diagrams. In Section 4 we use sheaf theory to define a reasonable cohomology theory of diagrams and compare it to previously defined theories. In Section 5 we define a closed model category structure for the homotopy theory of diagrams. We show this Quillen type homotopy theory is equivalent to the homotopy theory of J-CW complexes. In Section 6 we apply our constructions and results to prove a useful result in equivariant homotopy theory originally proved by Elmendorf by a different method.
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SOYLU YILMAZ, Elis. "4-Dimensional 2-Crossed Modules." Journal of New Theory, no. 40 (September 30, 2022): 46–53. http://dx.doi.org/10.53570/jnt.1148482.
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In this work, we defined a new category called 4-Dimensional 2-crossed modules. We identified the subobjects and ideals in this category. The notion of the subobject is a generalization of ideas like subsets from set theory, subspaces from topology, and subgroups from group theory. We then exemplified subobjects and ideals in the category of 4-Dimensional 2-crossed modules. A quotient object is the dual concept of a subobject. Concepts like quotient sets, spaces, groups, graphs, etc. are generalized with the notion of a quotient object. Using the ideal, we obtain the quotient of two subobjects and prove that the intersection of finite ideals is also an ideal in this category.
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Bachmann, Tom. "Motivic and real étale stable homotopy theory." Compositio Mathematica 154, no. 5 (March 20, 2018): 883–917. http://dx.doi.org/10.1112/s0010437x17007710.
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Let$S$be a Noetherian scheme of finite dimension and denote by$\unicode[STIX]{x1D70C}\in [\unicode[STIX]{x1D7D9},\mathbb{G}_{m}]_{\mathbf{SH}(S)}$the (additive inverse of the) morphism corresponding to$-1\in {\mathcal{O}}^{\times }(S)$. Here$\mathbf{SH}(S)$denotes the motivic stable homotopy category. We show that the category obtained by inverting$\unicode[STIX]{x1D70C}$in$\mathbf{SH}(S)$is canonically equivalent to the (simplicial) local stable homotopy category of the site$S_{\text{r}\acute{\text{e}}\text{t}}$, by which we mean thesmallreal étale site of$S$, comprised of étale schemes over$S$with the real étale topology. One immediate application is that$\mathbf{SH}(\mathbb{R})[\unicode[STIX]{x1D70C}^{-1}]$is equivalent to the classical stable homotopy category. In particular this computes all the stable homotopy sheaves of the$\unicode[STIX]{x1D70C}$-local sphere (over$\mathbb{R}$). As further applications we show that$D_{\mathbb{A}^{1}}(k,\mathbb{Z}[1/2])^{-}\simeq \mathbf{DM}_{W}(k)[1/2]$(improving a result of Ananyevskiy–Levine–Panin), reprove Röndigs’ result that$\text{}\underline{\unicode[STIX]{x1D70B}}_{i}(\unicode[STIX]{x1D7D9}[1/\unicode[STIX]{x1D702},1/2])=0$for$i=1,2$and establish some new rigidity results.
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Ozornova, Viktoriya, and Martina Rovelli. "The Duskin nerve of 2-categories in Joyal's cell category Θ2." Journal of Pure and Applied Algebra 225, no. 1 (January 2021): 106462. http://dx.doi.org/10.1016/j.jpaa.2020.106462.
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Treumann, David. "Exit paths and constructible stacks." Compositio Mathematica 145, no. 6 (September 21, 2009): 1504–32. http://dx.doi.org/10.1112/s0010437x09004229.
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AbstractFor a Whitney stratification S of a space X (or, more generally, a topological stratification in the sense of Goresky and MacPherson) we introduce the notion of an S-constructible stack of categories on X. The motivating example is the stack of S-constructible perverse sheaves. We introduce a 2-category EP≤2(X,S), called the exit-path 2-category, which is a natural stratified version of the fundamental 2-groupoid. Our main result is that the 2-category of S-constructible stacks on X is equivalent to the 2-category of 2-functors 2Funct(EP≤2(X,S),Cat) from the exit-path 2-category to the 2-category of small categories.
Dissertations / Theses on the topic "2-category theory"
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LUSTOSA, CECILIA REIS ENGLANDER. "2-CATEGORY AND PROOF THEORY." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2009. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=15181@1.
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CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICODedução Natural para a lógica intuicionista tem sido relacionada à Teoria das Categorias através do que agora é conhecido por Lógica Categórica. Essa relação é fortemente baseada no isomorfismo de Curry-Howard entre Dedução Natural e (lambda)-Cálculo Tipado. Esta dissertação descreve alguns aspectos dessa relação com o objetivo de propor uma visão 2-categórica da Lógica Categórica. Mostramos que mesmo numa visão 2-cateórica algumas desvantagens conhecidas na Teoria das Categorias continuam valendo. Concluímos essa dissertação discutindo as vantagens de uma visão 2-categórica a partir de premissas mais fracas.
Natural Deduction for intuitionistic logic has been related to Category Theory by what now is known as Categorical Logic. This relationship is strongly based on the Curry-Howard Isomorphism between Natural Deduction and typed (lambda)-Calculus. This dissertation describes some aspects of these relationship with the aim of proposing a 2-categorical view of categorical logic. We show that even under this 2-categorical view some of the drawbacks already known in ordinary Category Theory remain holding. We conclude this dissertation discussing the advantages of 2-categorical view under some weaker assumptions.
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Forsberg, Love. "Semigroups, multisemigroups and representations." Doctoral thesis, Uppsala universitet, Matematiska institutionen, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-327270.
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This thesis consists of four papers about the intersection between semigroup theory, category theory and representation theory. We say that a representation of a semigroup by a matrix semigroup is effective if it is injective and define the effective dimension of a semigroup S as the minimal n such that S has an effective representation by square matrices of size n. A multisemigroup is a generalization of a semigroup where the multiplication is set-valued, but still associative. A 2-category consists of objects, 1-morphisms and 2-morphisms. A finitary 2-category has finite dimensional vector spaces as objects and linear maps as morphisms. This setting permits the notion of indecomposable 1-morphisms, which turn out to form a multisemigroup. Paper I computes the effective dimension Hecke-Kiselman monoids of type A. Hecke-Kiselman monoids are defined by generators and relations, where the generators are vertices and the relations depend on arrows in a given quiver. Paper II computes the effective dimension of path semigroups and truncated path semigroups. A path semigroup is defined as the set of all paths in a quiver, with concatenation as multiplication. It is said to be truncated if we introduce the relation that all paths of length N are zero. Paper III defines the notion of a multisemigroup with multiplicities and discusses how it better captures the structure of a 2-category, compared to a multisemigroup (without multiplicities). Paper IV gives an example of a family of 2-categories in which the multisemigroup with multiplicities is not a semigroup, but where the multiplicities are either 0 or 1. We describe these multisemigroups combinatorially.
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Schröder, Nadine. "Using Multidimensional Item Response Theory Models to Explain Multi-Category Purchases." Vahlen, 2017. http://epub.wu.ac.at/6538/1/0344%2D1369%2D2017%2D2%2D27.pdf.
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We apply multidimensional item response
theory models (MIRT) to analyse multi-category
purchase decisions. We further compare
their performance to benchmark models by
means of topic models. Estimation is based
on two types of data sets. One contains only
binary the other polytomous purchase decisions.
We show that MIRT are superior
w. r. t. our chosen benchmark models. In particular,
MIRT are able to reveal intuitive latent
traits that can be interpreted as characteristics
of households relevant for multi-category
purchase decisions. With the help of latent
traits marketers are able to predict future purchase
behaviour for various types of households.
These information may guide shop
managers for cross selling activities and product
recommendations.
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Mendonça, Hudson Kazuo Teramoto. "Teorias de 2-gauge e o invariante de Yetter na construção de modelos com ordem topológica em 3-dimensões." Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/43/43134/tde-01082017-155641/.
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Ordem topológica descreve fases da matéria que não são caracterizadas apenas pelo esquema de quebra de simetria de Landau. Em 2-dimensões ordem topológica é caracterizada, entre outras propriedades, pela existência de uma degenerescência do estado fundamental que é robusta sobre perturbações locais arbitrarias. Com o proposito de entender o que caracteriza e classifica ordem topológica 3-dimensional o presente trabalho apresenta um modelo quântico exatamente solúvel em 3-dimensões que generaliza os modelos em 2-dimensões baseados em teorias de gauge. No modelo proposto o grupo de gauge é substituído por um 2-grupo. A Hamiltonia, que é dada por uma soma de operadores locais, é livre de frustrações. Provamos que a degenerescência do estado fundamental nesse modelo é dado pelo invariante de Yetter da variedade 4-dimensional Sigma × S¹, onde Sigma é a variedade 3-dimensional onde o modelo está definido.Topological order describes phases of matter that cannot be described only by the symmetry breaking theory of Landau. In 2-dimensions topological order is characterized, among other properties, by the presence of a ground state degeneracy that is robust to arbitrary local perturbations. With the purpose of understanding what characterizes and classify 3-dimensional topological order this works presents an exactly soluble quantum model in 3-dimensions that generalize 2-dimensional models constructed using gauge theories. In the model we propose the gauge group is replaced by a 2-group. The Hamiltonian, that is given by a sum of local commuting operators, is frustration free. We prove that the ground state degeneracy of this model is given by the Yetters invariant of the 4-dimensional manifold Sigma × S¹, where Sigma is the 3-dimensional manifold the model is defined.
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Barin, Ozlem. "The Role Of Imagination In Kant'." Master's thesis, METU, 2003. http://etd.lib.metu.edu.tr/upload/2/1110089/index.pdf.
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The purpose of this study is to examine the role of imagination in Immanuel Kant’
s Critique of Pure Reason by means of a detailed textual analysis and interpretation. In my systematic reading of the Kantian text, I analyse how the power of imagination comes to the foreground of Kant&
#8217
s investigation into the transcendental conditions of knowledge. This is to explain the mediating function of imagination between the two distinct faculties of the subject
between sensibility and understanding. Imagination achieves its mediating function between sensibility and understanding through its activity of synthesis. By means of exploring the features of the activity of synthesis I attempt to display that imagination provides the ground of the unification of sensibility and understanding. The argument of this study resides in the claim that the power of imagination, through its transcendental synthesis, provides the ground of the possibility of all knowledge and experience. This is to announce imagination as the building block of Kant&
#8217
s Copernican Revolution that grounds the objectivity of knowledge in its subjective conditions. Therefore, the goal of this study is to display imagination as a distinctive human capacity that provides the relation of our knowledge to the objects.
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Nguyen, Le Chi Quyet. "Une description fonctorielle des K-théories de Morava des 2-groupes abéliens élémentaires." Thesis, Angers, 2017. http://www.theses.fr/2017ANGE0032/document.
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Le but de cette thèse est l'étude, d'un point de vue fonctoriel, des K-théories de Morava modulo 2 des 2-groupes abéliens élémentaires. Autrement dit, nous étudions les foncteurs covariants $V \mapsto K(n)^*(BV^{\sharp})$ pour le premier p=2 et n un entier positif.Le cas n=1, qui résulte directement du travail d'Atiyah sur la K-théorie topologique, nous donne un foncteur coanalytique qui ne possède aucun sous-foncteur polynomial non-constant. Il est très différent du cas n>1, où les foncteurs mentionnés ci-dessus s'avèrent être analytiques.La théorie de Henn-Lannes-Schwartz fournit une correspondance entre les foncteurs analytiques et les modules instables sur l'algèbre de Steenrod. Nous déterminons le module instable correspondant au foncteur analytique $V \mapsto K(2)^*(BV^{\sharp})$, en étudiant la relation entre ce foncteur et la structure d'anneau de Hopf de l'homologie de l'omega-spectre associé à la théorie K(2)The aim of this PhD thesis is to study, from a functorial point of view, the mod 2 Morava K-theories of elementary abelian 2-groups. Namely, we study the covariant functors $V \mapsto K(n)^*(BV^{\sharp})$ for the prime p=2 and n a positive integer.The case n=1, which follows directly from the work of Atiyah on topological K-theory, gives us a coanalytic functor which contains no non-constant polynomial sub-functor. This is very different from the case n>1, where the above-mentioned functors are analytic.The theory of Henn-Lannes-Schwartz provides a correspondence between analytic functors and unstable modules over the Steenrod algebra. We determine the unstable module corresponding to the analytic functor $V \mapsto K(2)^*(BV^{\sharp})$, by studying the relation between this functor and the Hopf ring structure of the homology of the omega-spectrum associated to the theory K(2)
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Collier, Braxton Livingston. "Infinitesimal symmetries of Dixmier-Douady gerbes." Thesis, 2012. http://hdl.handle.net/2152/ETD-UT-2012-08-6066.
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This thesis introduces the infinitesimal symmetries of Dixmier-Douady gerbes over smooth manifolds. The collection of these symmetries are the counterpart for gerbes of the Lie algebra of circle invariant vector fields on principal circle bundles, and are intimately related to connective structures and curvings. We prove that these symmetries possess a Lie 2-algebra structure, and relate them to equivariant gerbes via a "differentiation functor". We also explain the relationship between the infinitesimal symmetries of gerbes and other mathematical structures including Courant algebroids and the String Lie 2-algebra.text
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Roberts, David Michael. "Fundamental bigroupoids and 2-covering spaces." Thesis, 2010. http://hdl.handle.net/2440/62680.
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This thesis introduces two main concepts: a fundamental bigroupoid of a topological groupoid and 2-covering spaces, a categorification of covering spaces. The first is applied to the second to show, among other things, that the fundamental 2-group of the 2-covering space is a sub-2-group of the fundamental 2-group of the base. Along the way we derive general results about localisations of the 2-categories of categories and groupoids internal to a site at classes of weak equivalences, construct a topological fundamental bigroupoid of locally well-behaved spaces, and finish by providing a rich source of examples of 2-covering spaces, including a functorial 2-connected 2-covering space.Thesis (Ph.D.) -- University of Adelaide, School of Mathematical Sciences, 2010
Books on the topic "2-category theory"
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Pantev, Tony. Stacks and catetories in geometry, topology, and algebra: CATS4 Conference Higher Categorical Structures and Their Interactions with Algebraic Geometry, Algebraic Topology and Algebra, July 2-7, 2012, CIRM, Luminy, France. Providence, Rhode Island: American Mathematical Society, 2015.
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Pitt, David, Samson Abramsky, Axel Poigné, and David Rydeheard, eds. Category Theory and Computer Programming. Berlin, Heidelberg: Springer Berlin Heidelberg, 1986. http://dx.doi.org/10.1007/3-540-17162-2.
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Makkai, Mihály. Models, logics, and higher-dimensional categories: A tribute to the work of Mihaly Makkai. Providence, R.I: American Mathematical Society, 2011.
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Gray, J. W. Formal Category Theory: Adjointness For 2-Categories. Springer London, Limited, 2006.
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Johnson, Niles, and Donald Yau. 2-Dimensional Categories. Oxford University Press, 2021. http://dx.doi.org/10.1093/oso/9780198871378.001.0001.
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2-Dimensional Categories provides an introduction to 2-categories and bicategories, assuming only the most elementary aspects of category theory. A review of basic category theory is followed by a systematic discussion of 2-/bicategories; pasting diagrams; lax functors; 2-/bilimits; the Duskin nerve; the 2-nerve; internal adjunctions; monads in bicategories; 2-monads; biequivalences; the Bicategorical Yoneda Lemma; and the Coherence Theorem for bicategories. Grothendieck fibrations and the Grothendieck construction are discussed next, followed by tricategories, monoidal bicategories, the Gray tensor product, and double categories. Completely detailed proofs of several fundamental but hard-to-find results are presented for the first time. With exercises and plenty of motivation and explanation, this book is useful for both beginners and experts.
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Heunen, Chris, and Jamie Vicary. Categories for Quantum Theory. Oxford University Press, 2019. http://dx.doi.org/10.1093/oso/9780198739623.001.0001.
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Monoidal category theory serves as a powerful framework for describing logical aspects of quantum theory, giving an abstract language for parallel and sequential composition and a conceptual way to understand many high-level quantum phenomena. Here, we lay the foundations for this categorical quantum mechanics, with an emphasis on the graphical calculus that makes computation intuitive. We describe superposition and entanglement using biproducts and dual objects, and show how quantum teleportation can be studied abstractly using these structures. We investigate monoids, Frobenius structures and Hopf algebras, showing how they can be used to model classical information and complementary observables. We describe the CP construction, a categorical tool to describe probabilistic quantum systems. The last chapter introduces higher categories, surface diagrams and 2-Hilbert spaces, and shows how the language of duality in monoidal 2-categories can be used to reason about quantum protocols, including quantum teleportation and dense coding. Previous knowledge of linear algebra, quantum information or category theory would give an ideal background for studying this text, but it is not assumed, with essential background material given in a self-contained introductory chapter. Throughout the text, we point out links with many other areas, such as representation theory, topology, quantum algebra, knot theory and probability theory, and present nonstandard models including sets and relations. All results are stated rigorously and full proofs are given as far as possible, making this book an invaluable reference for modern techniques in quantum logic, with much of the material not available in any other textbook.
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Hilton, P. J. Category Theory, Homology Theory and Their Applications. Proceedings of the Conference Held at the Seattle Research Center of the Battelle Memorial Institute, June 24 - July 19 1968: Volume 2. Springer London, Limited, 2006.
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Caramello, Olivia. Topos-theoretic background. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780198758914.003.0003.
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This chapter provides the topos-theoretic background necessary for understanding the contents of the book; the presentation is self-contained and only assumes a basic familiarity with the language of category theory. The chapter begins by reviewing the basic theory of Grothendieck toposes, including the fundamental equivalence between geometric morphisms and flat functors. Then it presents the notion of first-order theory and the various deductive systems for fragments of first-order logic that will be considered in the course of the book, notably including that of geometric logic. Further, it discusses categorical semantics, i.e. the interpretation of first-order theories in categories possessing ‘enough’ structure. Lastly, the key concept of syntactic category of a first-order theory is reviewed; this notion will be used in Chapter 2 for constructing classifying toposes of geometric theories.
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Faltings, Gerd. Facsimile : A p-adic Simpson correspondence. Princeton University Press, 2017. http://dx.doi.org/10.23943/princeton/9780691170282.003.0007.
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This chapter presents the facsimile of Gerd Faltings' article entitled “A p-adic Simpson Correspondence,” reprinted from Advances in Mathematics 198(2), 2005. In this article, an equivalence between the category of Higgs bundles and that of “generalized representations” of the étale fundamental group is constructed for curves over a p-adic field. The definition of “generalized representations” uses p-adic Hodge theory and almost étale coverings, and it includes usual representations which form a full subcategory. The equivalence depends on the choice of an exponential function for the multiplicative group. The method used in the proofs is the theory of almost étale extensions. A nonabelian Hodge–Tate theory is also developed.
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Giliola, Negrini, ed. Categorie, oggetti e strutture della conoscenza =: Categories, objects, and structures of knowledge : atti del Seminario organizzato dall'Istituto di Studi sulla ricerca e documentazione scientifica, Roma, 1-2 dicembre 1994. Roma: Consiglio nazionale delle ricerche, Istituto di studi sulla ricerca e documentazione scientifica, 1995.
Find full textBook chapters on the topic "2-category theory"
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Paoli, Simona. "Techniques from 2-Category Theory." In Algebra and Applications, 71–86. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-05674-2_4.
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Fiore, Marcelo, and Philip Saville. "Relative Full Completeness for Bicategorical Cartesian Closed Structure." In Lecture Notes in Computer Science, 277–98. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-45231-5_15.
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AbstractThe glueing construction, defined as a certain comma category, is an important tool for reasoning about type theories, logics, and programming languages. Here we extend the construction to accommodate ‘2-dimensional theories’ of types, terms between types, and rewrites between terms. Taking bicategories as the semantic framework for such systems, we define the glueing bicategory and establish a bicategorical version of the well-known construction of cartesian closed structure on a glueing category. As an application, we show that free finite-product bicategories are fully complete relative to free cartesian closed bicategories, thereby establishing that the higher-order equational theory of rewriting in the simply-typed lambda calculus is a conservative extension of the algebraic equational theory of rewriting in the fragment with finite products only.
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Corradini, A., and F. Gadducci. "A 2-categorical presentation of term graph rewriting." In Category Theory and Computer Science, 87–105. Berlin, Heidelberg: Springer Berlin Heidelberg, 1997. http://dx.doi.org/10.1007/bfb0026983.
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Andreev, A., and S. Soloviev. "A deciding algorithm for linear isomorphism of types with complexity O(nlog 2(n))." In Category Theory and Computer Science, 197–209. Berlin, Heidelberg: Springer Berlin Heidelberg, 1997. http://dx.doi.org/10.1007/bfb0026989.
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Fuchs-Kittowski, Klaus. "The Responsibility of Science for Guaranteeing Human Rights in the Fight Against Human Degradation, Racism and Anti-Semitism." In Studies in History and Philosophy of Science, 203–19. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-030-91597-1_10.
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AbstractThis article is an appeal in the form of ten questions or theses, which as a whole outline the responsibility of science. 1) The humanistic mission of science, respecting human rights, against reductionism; 2) Against reification and the degradation of the living; 3) Information creation: An essential category for model and theory development and as a general methodological guiding principle! 4) The need for education and training against racism: The responsibility of science in the fight against anti-Semitism; 5) Deadly science: The demand for the destruction of life unworthy of life was “scientifically” justified; 6) Religious traditions as a cause of anti-Semitism? 7) Causes of anti-humanism, racism, anti-Semitism, and neo-Nazism in the contemporary world of work; A deeper “perception” of life and human beings is also necessary in the economy! 8) People must be able to recognize the meaning and purpose of their existence 9) Peace must be secured! 10) Science can follow its humanistic obligation to serve life, to serve mankind.
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Carpita, Maurizio, and Silvia Golia. "Prediction of wine sensorial quality: a classification problem." In Proceedings e report, 235–38. Florence: Firenze University Press, 2021. http://dx.doi.org/10.36253/978-88-5518-461-8.44.
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When dealing with a wine, it is of interest to be able to predict its quality based on chemical and/or sensory variables. There is no agreement on what wine quality means, or how it should be assessed and it is often viewed in intrinsic (physicochemical, sensory) or extrinsic (price, prestige, context) terms (Jackson, 2017). In this paper, the wine quality was evaluated by experienced judges who scored the wine on the base of a 0-10 scale, with 0 meaning very bad and 10 excellent, so, the resulting variable was categorical. The models applied to predict this variable provide the prediction of the occurrence probabilities of each of its categories. Nevertheless, jointly with this probabilities’ record, the practitioners need the predicted value (category) of the variable, so the statistical problem to be covered refers to the way in which this probabilities’ record is transformed into a single value. In this paper we compare the predictive performances of the default method (Bayes Classifier - BC), which assigns a unit to the most likely category, and other two methods (Maximum Difference Classifier and Maximum Ratio Classifier). The BC is the optimal criterion if one is interested in the accuracy of the classification, but, given that it favors the prevalent category most, when there is not a category of interest, it cannot be the best choice. The data under study concern the quality of the red variant of the Portuguese "Vinho Verde" wine (Cortez et al., 2009), measured on a 0-10 scale. Nevertheless, only 6 scores were used, with 2 scores with a very few number of observations, so this is the right context for predictive performance comparisons. In the study, we investigated different merging of categories and we used 11 explanatory variables to estimate the probabilities’ record of the wine quality variable.
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Yu, Xiu-bao. "Why Are There Over 90 Definitions of the Strategy Concept?" In Management for Professionals, 7–27. Singapore: Springer Singapore, 2021. http://dx.doi.org/10.1007/978-981-33-4713-7_2.
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AbstractOutline: Based on the Three-multiple problem of literature on strategy definition, this chapter analyses literature on strategy definition based on a special research approach developed by the author. The reasons for the aforesaid Three-multiple problem are examined with a sample over 30 definitions. It is found that there are mainly four reasons contributing to the Three-multiple problem. (1) different wordings are used to express the same meaning; (2) a variety of wordings are used to illustrate the content of different sub-classes that are under the same category; (3) different understandings of the strategy concept cause the use of various wordings; (4) extensions of concept are included in literature on strategy definition.
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Iwamura, Masakazu, Yoshihiko Inoue, Kazunori Minatani, and Koichi Kise. "Suitable Camera and Rotation Navigation for People with Visual Impairment on Looking for Something Using Object Detection Technique." In Lecture Notes in Computer Science, 495–509. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-58796-3_57.
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AbstractFor people with visual impairment, smartphone apps that use computer vision techniques to provide visual information have played important roles in supporting their daily lives. However, they can be used under a specific condition only. That is, only when the user knows where the object of interest is. In this paper, we first point out the fact mentioned above by categorizing the tasks that obtain visual information using computer vision techniques. Then, in looking for something as a representative task in a category, we argue suitable camera systems and rotation navigation methods. In the latter, we propose novel voice navigation methods. As a result of a user study comprised of seven people with visual impairment, we found that (1) a camera with a wide field of view such as an omnidirectional camera was preferred, and (2) users have different preferences in navigation methods.
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Paegelow, Martin, and David García-Álvarez. "Advanced Pattern Analysis to Validate Land Use Cover Maps." In Land Use Cover Datasets and Validation Tools, 229–54. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-030-90998-7_12.
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AbstractIn this chapter we explore pattern analysis for categorical LUC maps as a means of validating land use cover maps, land change and land change simulations. In addition to those described in Chap. “Spatial Metrics to Validate Land Use Cover Maps”, we present three complementary methods and techniques: a Goodness of Fit metric to measure the agreement between two maps in terms of pattern (Map Curves), the focus on changes on pattern borders as a method for validating on-border processes and a technique quantifying the magnitude of distance error. Map Curves (Sect. 1) offers a universal pattern-based index, called Goodness of Fit (GOF), which measures the spatial concordance between categorical rasters or vector layers. Complementary to this pattern validation metric, the following Sect. 2 focuses specifically on the changes that take place on pattern borders. This enables changes to be divided into those that take place on the borders of existing features and those that form new, disconnected features. Bringing this chapter on landscape patterns to a close, Sect. 3 presents a technique for quantifying allocation errors in simulation maps and more precisely on the minimum distance between the allocation errors in simulation maps and the nearest patch belonging to the same category on the reference map. The comparison between a raster-based and a vector-based approach brings us back to the differences in measurement inherent in the representation of entities in raster and vector mode. These techniques are applied to two datasets. Section 1 uses the Asturias Central Area database, where CORINE maps are compared to SIOSE maps and simulation outputs. For their part, the techniques described in Sects. 2 and 3 are applied to the Ariège Valley database. CORINE maps for 2000 and 2018 are used as reference maps in comparisons with simulated land covers.
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García-Álvarez, David, Javier Lara Hinojosa, Francisco José Jurado Pérez, and Jaime Quintero Villaraso. "Global General Land Use Cover Datasets with a Time Series of Maps." In Land Use Cover Datasets and Validation Tools, 287–311. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-030-90998-7_15.
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AbstractGeneral Land Use Cover (LUC) datasets provide a holistic picture of all the land uses and covers on Earth, without focusing specifically on any individual land use category. As opposed to the LUC maps which are only available for one date or year, reviewed in Chap. “Global General Land Use Cover Datasets with a Single Date”, the maps with time series allow users to study LUC change over time. Time series of general LUC datasets at a global scale is useful for understanding global patterns of LUC change and their relation with global processes such as climate change or the loss of biodiversity. MCD12Q1, also known as MODIS Land Cover, was the first time series of LUC maps to be produced on a global scale. When it was first launched in 2002, there were already many organizations and researchers working on accurate, detailed global LUC maps, although these were all one-off editions for single years. The MCD12Q1 dataset continues to be updated today, providing a series of maps for the period 2001–2018. Since the launch of MCD12Q1, many other historical series of LUC maps have been produced, especially in the last decade. This has resulted in the LUC map series covering a longer time period at higher spatial resolution. Recent efforts have focused on producing consistent time series of maps that can track LUC changes over time with low levels of uncertainty. GLCNMO (500 m), GlobCover (300 m) and GLC250 (250 m) provide time series of LUC maps at similar spatial resolutions to MCD12Q1 (500 m), although for fewer reference years. GLCNMO provides information for the years 2003, 2008 and 2013, GlobCover for 2005 and 2009 and GLC250 for 2001 and 2010. GLASS-GLC is the dataset with the coarsest spatial resolution of all those reviewed in this chapter (5 km), even though it was released very recently, in 2020. Map producers have focused on this dataset’s long timespan (1982–2015) rather than on its spatial detail. LC-CCI and CGLS-LC100 are the recently launched datasets providing a consistent series of LUC maps, which show LUC changes over time with lower levels of uncertainty. LC-CCI provides LUC information for one of the longest timespans reviewed here (1992–2018) at a spatial resolution of 300 m. CGLS-LC100 provides LUC information for a shorter period (2015–2019) but at a higher spatial resolution (100 m). In both cases, updates are scheduled. The datasets with the highest levels of spatial detail are FROM-GLC and GLC30. These were produced using highly detailed Landsat imagery, delivering time series of maps at 30 m. The FROM-GLC project even has a test LUC map at a spatial resolution of 10 m from Sentinel-2 imagery for the year 2017, making it the global dataset with the greatest spatial detail of all those reviewed in this book. Both FROM-GLC and GLC30 provide data for three different dates: the former for 2010, 2015 and 2017 and the latter for 2000, 2010 and 2020.
Conference papers on the topic "2-category theory"
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Goode, Natassia, Paul M. Salmon, Michael G. Lenné, and Caroline F. Finch. "A Test of a Systems Theory-Based Incident Coding Taxonomy for Risk Managers." In Applied Human Factors and Ergonomics Conference. AHFE International, 2019. http://dx.doi.org/10.54941/ahfe100161.
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Organizations need to be able to collect reliable and accurate data on the causal factors that lead to near misses and injury causing incidents in order to design appropriate, informed, safety interventions. The aim of this study was to test the inter-rater reliability of a prototype taxonomy for classifying the causal factors involved in incidents in the outdoor education and recreation sector. The taxonomy consists of three levels, where each category level breaks the previous one down into a finer level of detail. The study involved 14 respondents, who play a key role in risk management within their organization, using the taxonomy to code 10 detailed incident reports. The incident reports were composited from reports and enquiries into actual events, and ranged in injury severity from fractures to fatalities. Participants were asked to: 1) identify the causal factors involved in each incident; and 2) identify the code/s from the taxonomy which best described those causal factors. The study demonstrated that the taxonomy can be used by risk managers to identify and code causal factors across all levels of the led outdoor activity system. However, identifying appropriate codes at the second and third level of detail was problematic.
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Ryseck, Peter, Emily Glover, Mark Lopez, Rajneesh Singh, and Inderjit Chopra. "Steady and Transient Hover Performance Investigation of Electric Medium-sized Variable-RPM Rotor." In Vertical Flight Society 78th Annual Forum & Technology Display. The Vertical Flight Society, 2022. http://dx.doi.org/10.4050/f-0078-2022-17448.
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Electric variable RPM rotors are increasingly being used for propulsion and control of unmanned air vehicles. As these vehicles scale to carry heavier payloads of 50 to 400 lbs (20 to 180 kgs) in the group 2 and 3 UAS category, there are concerns about their aerodynamic performance and handling quality degradation. First, a universal electric powered experimental testing rig designed for use on a hover tower and in a wind tunnel is described. Second, steady hover data is estimated using blade element momentum theory. These predictions incorporate an empirical correction approach and an interpolation approach to capture Reynolds number variation along the span of the blade and variation with RPM. Results show good agreement with the interpolation method for the low Reynolds number rotor tested. Finally, transient step and chirp inputs are presented. The chirp inputs were used in CIFER to validate the results of the experiment and fit transfer functions of thrust and torque due to RPM and RPM2.
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Riccardi, Fabio, Federico DelGrande, Giuliano Prando, Valentina Giuliani, Matteo Pecoraro, and Andrea Ragazzi. "NGCTR-TD Tiltrotor Autorotation Numerical Investigation." In Vertical Flight Society 78th Annual Forum & Technology Display. The Vertical Flight Society, 2022. http://dx.doi.org/10.4050/f-0078-2022-17551.
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Within the Clean Sky 2 Fast Rotorcraft platform, a Next Generation Civil Tilt-Rotor Technology Demonstrator (NGCTR-TD) is under development. The design phase has been successfully completed and first flight phase is planned within 2023. As part of design verification, the capability to perform a safe landing procedure after losing all engines power is investigated, with dedicated analysis planned in order to improve the transport category performance requirements, as verified for Legacy tilt-rotor platform. Such procedure consists in 4 different steps when starting from AP mode, and the analysis are focused on VTOL steady autorotation phase, being the one where tilt-rotor configuration shows higher peculiarity with respect to helicopter configuration, due to the presence of lifting surfaces. As first, preliminary considerations from helicopter theory are cited, and tilt-rotor peculiarities listed. Then, adopting the developed FlightLab numerical model, different solutions are investigated, starting from characterization in airspeed for a baseline configuration. Different sensitivity analyses are conducted to map the major effect for the specific topic, and best trade-off autorotation configuration/control strategy is obtained for NGCTR-TD. Such solution is investigated in the complete Weight/CG envelope to ensure control strategy robustness.
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Epple, Philipp, Matthias Semel, Bettina Willinger, and Antonio Delgado. "Compact Test Rig Design for Fans and Blowers." In ASME 2014 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/imece2014-38972.
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In order to develop high efficiency fans and blowers the design methods are being improved continuously. The same is valid for the modern CFD (Computational Fluid Dynamics) programs, which are used in the design process in order to validate the designs. However, at the end of the development process measurements at test rigs are needed in order to verify the final design. CFD is substituting to some extend EFD (Experimental Fluid Dynamics), but still EFD is the final way to evaluate a design. Usually the universities and the industry have some test rig where measurements are done. These test rigs in general are unique and built according to a corresponding standard. However, these standards, as for example the German DIN 24 163 [1] or the European DIN EN ISO 5801 [2] prescribe only the main proportions of such test rigs while several important features are not described in detail. In particular the aerodynamic theory behind the standard is very often omitted. For example, the measurement of the pressure characteristic of a fan is performed at a pressure tab at the test chamber wall and not at the fan itself. How to assure that the pressure measured at the wall tab corresponds to the fan pressure? In this work the relevant theory behind the design of test rigs was worked out in detail for the relevant test rig features where the standards do not explain the fluid mechanical aspects. On this basis pressure and suction side test rigs were designed and completely simulated with a commercial CFD program, Ansys CFX. The goal was to develop compact test rigs according to the European DIN EN ISO 5801 [2] standard. It is shown in this work how the size of the test chamber influences the measuring results. Furthermore an in detail CFD study of a series of flow measurement devices, as inlet and Venturi nozzles, was performed. In such a way it was possible to show the influence of the dimensions of these devices on the accuracy of the measurements. Finally two test rigs were built, one for suction side and the other one for pressure side measurements. Compared to other test rigs in this category in use in the industry in Germany it was possible to reduce the size of these test rigs by a factor of about two complying with the measurement uncertainty of the DIN EN ISO 5801 standard.
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De Preter, Peter, William Wacquier, and Wim Cool. "The Belgian Program for Low and Intermediate Short Lived Waste Management: From 1985 to License Application." In ASME 2013 15th International Conference on Environmental Remediation and Radioactive Waste Management. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/icem2013-96251.
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On 31 Januray 2013, ONDRAF/NIRAS, the Belgian Agency for Radioactive Waste and Enriched Fissile Materials, has introduced the construction and operation license application for the surface disposal facility for category A waste at Dessel. The objective of this paper is to present the development of this national programme. First the key milestones and their impact on the development of the project will be highlighted. This includes in particular: 1) the turning point in 1994, when ONDRAF/NIRAS converts its purely techno-scientific work method into an approach of participation that allows for societal aspects to be taken into account and 2) the decision of the government in 2006 in favour of the surface disposal of category A waste in Dessel. Then the paper presents the pillars of the long-term safety of a surface disposal and the principles for site selection and how they were applied to the surface disposal facility for category A waste at Dessel. The pillars of the long-term safety of a surface disposal are: (1) the passive confinement and isolation provided by the Engineering Barrier System, (2) the contribution to this passive isolation and confinement by the site, (3) the limitation of the radioactive source term, and (4) the control and monitoring measures.
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Lin a Hsiao-Ting Lu b, Yu-Cheng, and Hsin-Chieh Wu c. "The Study of Work Ability for the Staff of Chain Hair Salons in Central Taiwan." In Applied Human Factors and Ergonomics Conference. AHFE International, 2019. http://dx.doi.org/10.54941/ahfe100167.
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With the social development and economy improvement in Taiwan, people are pursuing a better life quality. The “better life quality” maybe means a self-satisfied life style for most of young people in Taiwan. They pay more attention and spend more money and time on their appearance, just like their hair styles and dressing. The growing rate of number of employees in styles hair industry is about 2% per year. Musculoskeletal disorders and chemicals exposure are the major factors to affect the working ability for the employees in hair-styling industry. However, the situation becomes worse because of the rise and development of chain hair salons and prolonged working time. The purpose of this study is to investigate the work ability with the Work Ability Index Questionnaire for staff working at chain hair salons in central Taiwan, including supervisors, hair stylists and assistants. According to the result of Work Ability questionnaire, overall Work Ability Index (WAI) is 35.14 and the work ability category is “moderate”. If the gender is considered, the WAI for male and female are 37.26 and 33.8, and their work ability categories are “good” and “moderate” respectively. If the job position is considered, only the work ability category for supervisors/branch manager is good. There are significant differences of work ability between job positions and gender. Thus, the present situation of work ability for these hair-styling staff in central Taiwan is evident and related improvement suggestions are made.
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Farkas, Steven E. "Selecting HLR and SR Standards for PRA Applications." In 16th International Conference on Nuclear Engineering. ASMEDC, 2008. http://dx.doi.org/10.1115/icone16-48598.
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This white paper provides guidance for mapping risk informed applications to PRA Scope and Technical Adequacy requirements. The discussion considers regulatory guidance contained in SRP 19.1 “Determining the Technical Adequacy of Probabilistic Risk Assessment Results for Risk Informed Activities” and supplements industry guidance on application mapping contained in Section 3 “Risk Assessment Application Process of the ASME Standard for the PRA for Nuclear Power Plant Applications,” of the ASME PRA Standard with Regulatory Guide 1.200 clarifications. The general processes identified in this paper should also be applicable to mapping applications to any of the forthcoming ANS standard requirements. The aim of this white paper is to help identify which ASME PRA Standard High Level Requirements (HLRs) fall in the scope of a particular “risk informed” application to the NRC that will, in part, justify the requested change with risk metrics. To obtain values for risk metrics, it is necessary to manipulate the plant PRA model. The question becomes what should be changed in the model to represent the “risk informed” topic at hand? Each HLR has a set of supporting requirements (SRs) graded by “Capability Categories.” For many supporting requirements (SRs) under each HLR, there is no difference between the three capability categories. At issue is what features of the model have to conform to Capability Category 2 when Capability Category 2 differs from Capability Category 1.
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Fessler, Raymond R., and Steve C. Rapp. "The Effect of Shallow Cracks on the Predicted Failure Pressure of Natural Gas Pipelines Containing Stress-Corrosion Cracks." In 2014 10th International Pipeline Conference. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/ipc2014-33088.
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Predicting the failure pressure from the dimensions of a defect in a pipe is a critical step in direct assessment and in-line inspection. There are reasonably accurate methods for regularly shaped defects, but predicting the failure pressure for stress-corrosion cracks is more difficult because of the irregular crack front and the existence of shallow cracks or shallow extensions of deeper cracks. This paper addresses the issue of shallow cracks. This is particularly important in the case of a very shallow crack that is long enough to be classified as Category 1, but is so shallow that is does not affect the strength of the pipe. It is common practice to assume that a Category 2 crack exists some place in that segment, and a hydrostatic test would be required, although such drastic action should not be necessary because of the negligible effects on the strength of the pipe. It has been suggested that grinding 10% of the wall thickness might be a useful way to define the effective length of cracks or cracks that have shallow extensions. The effect of removing shallow cracks by grinding was investigated by analyzing twenty-five cases for which the crack profile was known. The effect depends on how the crack depth profile is characterized and whether there is a neighboring crack nearby that might interact with the flaw of interest. It was found that grinding 10% off the wall thickness will affect a small percentage of the flaws (five of the twenty-five). For those that it does affect, if the crack depth is taken as the maximum depth, the predicted failure pressure (PFP) will be very conservative, and eliminating the shallow cracks will always make the PFP less conservative, but still more conservative than desired. If this method is used, decreasing the severity category by one should be considered.
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Pathapati, V. V. N. R. Prasad Raju, and A. C. Rao. "Gradation of Planar Mechanism Structures for Robot Arms Based on Their Structural Error Performance." In ASME 2001 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2001. http://dx.doi.org/10.1115/detc2001/dac-21113.
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Abstract Robot arms which received greater attention in the recent past are open chain linkages. Each joint in these robot arms, is actuated independently. While possessing many advantages such as large workspace and maneuverability, they do suffer from disadvantages like less rigidity, accumulation of mechanical errors from shoulder to end effector, control problems etc. The alternative to the open chain robot arms is the in-parallel actuator arrangement often referred to as the platform-type whose successful application is reported by many investigators. Multi-degree-of-freedom Mechanisms are now receiving active consideration for application as platform type robots. In fact in the literature, a number of distinct multi degree of freedom planar linkage mechanisms are available and all of them can be considered as platform type Robots. In this paper numerical measures are proposed to compare all the distinct planar linkage mechanisms at the conceptual stage of design in the category of 9 link, 2 degree of freedom and 10 link, 3 degree of freedom, from the view point of structural error performance. The proposed method is based on the deployment of design parameters in different topological features of the chain Viz., links, Joints and loops.
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Allen, John G. "Current and Voltage Choice for North American Railroad Electrifications: 1895-1931." In 2020 Joint Rail Conference. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/jrc2020-8004.
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Abstract The variety of currents and voltages adopted by North American railroads between 1895 and 1931 is sometimes seen as confusing. Railroads faced choices between direct current (DC) and alternating current (AC), as well as among different voltages. But closer analysis shows a clear order to the specifications chosen. The technology options available at the time and the intended functions of these installations explain the specifications that railroads chose. Railroads electrifying fell into three basic groups: 1. Early adopters (usually requiring electrification for tunnels), 2. Railroads electrifying after 1910 for commuter service, and 3. Railroads that electrified for, or at least with freight service in mind. Each of these faced very different sets of options, and made their choice of electrical specifications accordingly. There were four basic combinations of current and voltage: 1. Low-voltage DC delivered via third rail, 2. Medium-voltage DC, 3. Higher-voltage DC, and 4. AC (almost always single-phase at 11,000 Volts, 25 Hertz). For railroads in a given category, the practicable choices were in fact limited to one or two options. Contrary to what is sometimes thought, the different electrical specifications reflected an underlying logic, not disorder.
Reports on the topic "2-category theory"
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Schipper, Youdi, Isaac Mbiti, and Mauricio Romero. Designing and Testing a Scalable Teacher Incentive Programme in Tanzania. Research on Improving Systems of Education (RISE), September 2022. http://dx.doi.org/10.35489/bsg-rise-ri_2022/044.
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School participation in Tanzania has increased dramatically over the past two decades: primary school enrolment increased from 4.9 million in 2001 to 10.9 million in 2020. While 81 percent of primary-school-age children are currently enrolled, over the last ten years, the primary completion rate has dropped and remains below 70 percent since 2015 (data from UNESCO Institute for Statistics).1 Despite improvements in enrolment, indicators of foundational learning remain low. According to the 2020 report of the Standard Two National Assessment (STNA), conducted by the National Examinations Council of Tanzania (NECTA), in 2019 five percent of Grade 2 students pass the benchmark for reading proficiency (“Can correctly read exactly 50 words of the passage in one minute and with 80 percent or higher comprehension”). The report finds that 17 percent of students pass the benchmark (80 percent correct) of the addition and subtraction sub-tasks. These outcomes are not the result of students’ lack of academic aspiration: according to the RISE Tanzania baseline survey, 73 percent of Grade 2 and 3 students say they would like to complete secondary school or university. In a recent report, the Global Education Evidence Advisory Panel (World Bank, 2020) asked what programmes and policies are the most cost-effective instruments for addressing the learning crisis and improving learning for all children. The report creates three categories: the “great buys” category includes programmes that provide very low-cost but salient information on the benefits, costs, and quality of education. The “good buys” category includes programmes that provide structured pedagogy, instruction targeted by learning level, merit-based scholarships and pre-school interventions. Finally, the category “promising but low-evidence” includes teacher accountability and incentive reforms. KiuFunza, a teacher performance pay programme in Tanzania, fits this last category. KiuFunza (shorthand for Kiu ya Kujifunza or Thirst to Learn) provides test-score linked cash incentives to teachers in Grades 1, 2, and 3 to increase foundational literacy and numeracy outcomes for students. The programme is managed by Twaweza East Africa, a Civil Society Organization, and was set up to provide evidence on the impact of teacher incentives in a series of experimental evaluations. This note discusses the rationale for teacher incentives in Tanzania, the design elements of KiuFunza and preliminary results for the most recent phase of KiuFunza (this phase was implemented in 2019-2021 and the impact evaluation is part of the RISE Tanzania research agenda).
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Paynter, Robin A., Celia Fiordalisi, Elizabeth Stoeger, Eileen Erinoff, Robin Featherstone, Christiane Voisin, and Gaelen P. Adam. A Prospective Comparison of Evidence Synthesis Search Strategies Developed With and Without Text-Mining Tools. Agency for Healthcare Research and Quality (AHRQ), March 2021. http://dx.doi.org/10.23970/ahrqepcmethodsprospectivecomparison.
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Background: In an era of explosive growth in biomedical evidence, improving systematic review (SR) search processes is increasingly critical. Text-mining tools (TMTs) are a potentially powerful resource to improve and streamline search strategy development. Two types of TMTs are especially of interest to searchers: word frequency (useful for identifying most used keyword terms, e.g., PubReminer) and clustering (visualizing common themes, e.g., Carrot2). Objectives: The objectives of this study were to compare the benefits and trade-offs of searches with and without the use of TMTs for evidence synthesis products in real world settings. Specific questions included: (1) Do TMTs decrease the time spent developing search strategies? (2) How do TMTs affect the sensitivity and yield of searches? (3) Do TMTs identify groups of records that can be safely excluded in the search evaluation step? (4) Does the complexity of a systematic review topic affect TMT performance? In addition to quantitative data, we collected librarians' comments on their experiences using TMTs to explore when and how these new tools may be useful in systematic review search¬¬ creation. Methods: In this prospective comparative study, we included seven SR projects, and classified them into simple or complex topics. The project librarian used conventional “usual practice” (UP) methods to create the MEDLINE search strategy, while a paired TMT librarian simultaneously and independently created a search strategy using a variety of TMTs. TMT librarians could choose one or more freely available TMTs per category from a pre-selected list in each of three categories: (1) keyword/phrase tools: AntConc, PubReMiner; (2) subject term tools: MeSH on Demand, PubReMiner, Yale MeSH Analyzer; and (3) strategy evaluation tools: Carrot2, VOSviewer. We collected results from both MEDLINE searches (with and without TMTs), coded every citation’s origin (UP or TMT respectively), deduplicated them, and then sent the citation library to the review team for screening. When the draft report was submitted, we used the final list of included citations to calculate the sensitivity, precision, and number-needed-to-read for each search (with and without TMTs). Separately, we tracked the time spent on various aspects of search creation by each librarian. Simple and complex topics were analyzed separately to provide insight into whether TMTs could be more useful for one type of topic or another. Results: Across all reviews, UP searches seemed to perform better than TMT, but because of the small sample size, none of these differences was statistically significant. UP searches were slightly more sensitive (92% [95% confidence intervals (CI) 85–99%]) than TMT searches (84.9% [95% CI 74.4–95.4%]). The mean number-needed-to-read was 83 (SD 34) for UP and 90 (SD 68) for TMT. Keyword and subject term development using TMTs generally took less time than those developed using UP alone. The average total time was 12 hours (SD 8) to create a complete search strategy by UP librarians, and 5 hours (SD 2) for the TMT librarians. TMTs neither affected search evaluation time nor improved identification of exclusion concepts (irrelevant records) that can be safely removed from the search set. Conclusion: Across all reviews but one, TMT searches were less sensitive than UP searches. For simple SR topics (i.e., single indication–single drug), TMT searches were slightly less sensitive, but reduced time spent in search design. For complex SR topics (e.g., multicomponent interventions), TMT searches were less sensitive than UP searches; nevertheless, in complex reviews, they identified unique eligible citations not found by the UP searches. TMT searches also reduced time spent in search strategy development. For all evidence synthesis types, TMT searches may be more efficient in reviews where comprehensiveness is not paramount, or as an adjunct to UP for evidence syntheses, because they can identify unique includable citations. If TMTs were easier to learn and use, their utility would be increased.
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Allik, Mirjam, Dandara Ramos, Marilyn Agranonik, Elzo Pereira Pinto Junior, Maria Yury Ichihara, Mauricio Barreto, Alastair Leyland, and Ruth Dundas. Developing a Small-Area Deprivation Measure for Brazil. University of Glasgow, May 2020. http://dx.doi.org/10.36399/gla.pubs.215898.
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This report describes the development of the BrazDep small-area deprivation measure for the whole of Brazil. The measure uses the 2010 Brazilian Population Census data and is calculated for the smallest possible geographical area level, the census sectors. It combines three variables – (1) percent of households with per capita income ≤ 1/2 minimum wage; (2) percent of people not literate, aged 7+; and (3) average of percent of people with inadequate access to sewage, water, garbage collection and no toilet and bath/shower – into a single measure. Similar measures have previously been developed at the census sector level for some states or municipalities, but the deprivation measure described in this report is the first one to be provided for census sectors for the whole of Brazil. BrazDep is a measure of relative deprivation, placing the census sectors on a scale of material well-being from the least to the most deprived. It is useful in comparing areas within Brazil in 2010, but cannot be used to make comparisons across countries or time. Categorical versions of the measure are also provided, placing census sectors into groups of similar levels of deprivation. Deprivation measures, such as the one developed here, have been developed for many countries and are popular tools in public health research for describing the social patterning of health outcomes and supporting the targeting and delivery of services to areas of higher need. The deprivation measure is exponentially distributed, with a large proportion of areas having a low deprivation score and a smaller number of areas experiencing very high deprivation. There is significant regional variation in deprivation; areas in the North and Northeast of Brazil have on average much higher deprivation compared to the South and Southeast. Deprivation levels in the Central-West region fall between those for the North and South. Differences are also great between urban and rural areas, with the former having lower levels of deprivation compared to the latter. The measure was validated by comparing it to other similar indices measuring health and social vulnerability at the census sector level in states and municipalities where it was possible, and at the municipal level for across the whole of Brazil. At the municipal level the deprivation measure was also compared to health outcomes. The different validation exercises showed that the developed measure produced expected results and could be considered validated. As the measure is an estimate of the “true” deprivation in Brazil, uncertainty exists about the exact level of deprivation for all of the areas. For the majority of census sectors the uncertainty is small enough that we can reliably place the area into a deprivation category. However, for some areas uncertainty is very high and the provided estimate is unreliable. These considerations should always be kept in mind when using the BrazDep measure in research or policy. The measure should be used as part of a toolkit, rather than a single basis for decision-making. The data together with documentation is available from the University of Glasgow http: //dx.doi.org/10.5525/gla.researchdata.980. The data and this report are distributed under Creative Commons Share-Alike license (CC BY-SA 4.0) and can be freely used by researchers, policy makers or members of public.