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关键词： Stable infinity-categories   Triangulated categories   t-structures   Tilting theory   Semiorthogonal decompositions   Stability conditions on triangulated categories  

摘要： We exploit the equivalence between t-structures and normal torsion theories on a stable infinity-category to show how a few classical topics in the theory of triangulated categories, i.e., the characterization of bounded t-structures in terms of their hearts, their associated cohomology functors, semiorthogonal decompositions, and the theory of tiltings, as well as the more recent notion of Bridgeland's slicings, are all particular instances of a single construction, namely, the tower of a morphism associated with a J-slicing of a stable infinity-category C, where J is a totally ordered set equipped with a monotone Z-action.

关键词： CASP13   classification   fold space   free modeling   protein structure   sequence homologs   structure analogs   structure prediction   template-based modeling  

摘要： Protein target structures for the Critical Assessment of Structure Prediction round 13 (CASP13) were split into evaluation units (EUs) based on their structural domains, the domain organization of available templates, and the performance of servers on whole targets compared to split target domains. Eighty targets were split into 112 EUs. The EUs were classified into categories suitable for assessment of high accuracy modeling (or template-based modeling [TBM]) and topology (or free modeling [FM]) based on target difficulty. Assignment into assessment categories considered the following criteria: (a) the evolutionary relationship of target domains to existing fold space as defined by the Evolutionary Classification of Protein Domains (ECOD) database;(b) the clustering of target domains using eight objective sequence, structure, and performance measures;and (c) the placement of target domains in a scatter plot of target difficulty against server performance used in the previous CASP. Generally, target domains with good server predictions had close template homologs and were classified as TBM. Alternately, targets with poor server predictions represent a mixture of fast evolving homologs, structure analogs, and new folds, and were classified as FM or FM/TBM overlap.

关键词： Bag-of-words model   Category-preserving   Signal discrimination   Condition monitoring   Taguchi's quality engineering  

摘要： Signal discrimination contributes to the development of machine-machine and human-machine interactive intelligent systems. In this study, a novel framework for signal discrimination was proposed. The proposed framework comprised three phases. In Phase I, a waveform shape-based feature extraction method was used for parameterizing signals. In Phase II, a novel category-preserving bag-of-words (CPBoW) model was proposed. In Phase III, signals were discriminated using a vector space model with term frequency-inverse document frequency. The bag-of-words model generally demonstrated promising performance for signal discrimination. However, the inherent connections among signals of homogeneous categories were considerably lost during signal framing and codebook generation processes. This was because the codebook was simply generated by clustering signal frame samples in the Euclidean space. In the proposed CPBoW model, Taguchi's quality engineering method was used to develop a category-preserving distance metric for executing a clustering process to generate category-preserving codewords. This preserved category information in the codebook and consequently increased the effectiveness of the discrimination process. The proposed framework was verified through three condition monitoring applications that involved a musical instrument recognition problem, motor bearing fault recognition problem, and heart disease recognition problem. The results indicated the superior performance and effectiveness of the proposed framework.

关键词： cone beam computed tomography   convolutional neural network   data augmentation   deep convolutional neural network   deep learning   global average pooling   max pooling  

摘要： Accurately classify teeth category is important in further dental diagnosis. Analyzing huge dental data, that is, identifying the teeth category, is often a hard task. Current automatic methods are based on computer vision and deep learning approaches. In this study, we aimed to classify the teeth category into four classes: incisor, canine, premolar, and molar. Cone beam computed tomography was used to collect the data. We proposed a seven-layer deep convolutional neural network with global average pooling to identify teeth category. Data augmentation method was used to enlarge the size of training dataset. The results showed the sensitivities of incisor, canine, premolar, and molar teeth are 88%, 86%, 84%, and 90%, respectively. The average sensitivity is 87.0%. We validated max pooling gives better results than average pooling. Our method is better than three state-of-the-art approaches.

关键词： consumer purchase journey   deep learning   economic impact of text   product reviews   natural language processing   regression discontinuity in time  

摘要： How consumers use review content has remained opaque due to the unstructured nature of text and the lack of review-reading behavior data. The authors overcome this challenge by applying deep learning-based natural language processing on data that tracks individual-level review reading, searching, and purchasing behaviors on an e-commerce site to investigate how consumers use review content. They extract quality and price content from 500,000 reviews of 600 product categories and achieve two objectives. First, the authors describe consumers' review-content-reading behaviors. Although consumers do not read review content all the time, they do rely on it for products that are expensive or of uncertain quality. Second, the authors quantify the causal impact of read-review content on sales by using supervised deep learning to tag six theory-driven content dimensions and applying a regression discontinuity in time design. They find that aesthetics and price content significantly increase conversion across almost all product categories. Review content has a higher impact on sales when the average rating is higher, ratings variance is lower, the market is more competitive or immature, or brand information is not accessible. A counterfactual simulation suggests that reordering reviews based on content can have the same effect as a 1.6% price cut for boosting conversion.

关键词： Noncommutative metric geometry   Gromov-Hausdorff propinuity   Groupoid and group actions  

摘要： We prove a compactness result for classes of actions of many small categories on quantum compact metric spaces by Lipschitz linear maps, for the topology of the covariant Gromov-Hausdorff propinquity. In particular, our result applies to actions of proper groups by Lipschitz isomorphisms on quantum compact spaces. Our result provides a first example of a structure which passes to the limit of quantum metric spaces for the propinquity, as well as a new method to construct group actions, including from non-locally compact groups seen as inductive limits of compact groups, on unital C*-algebras. We apply our techniques to obtain some properties of closure of certain classes of quasi-Leibniz quantum compact metric spaces for the propinquity. (C) 2019 Elsevier B.V. All rights reserved.

关键词： Model theory   Simple theory   Pregeometry   Omega-categorical theory   Elimination of quantifiers   Homogeneous structure  

摘要： We prove that if T is an omega-categorical supersimple theory with nontrivial dependence (given by forking), then there is a nontrivial regular 1-type over a finite set of reals which is realized by real elements;hence forking induces a nontrivial pregeometry on the solution set of this type and the pregeometry is definable (using only finitely many parameters). The assumption about omega-categoricity is necessary. This result is used to prove the following: If V is a finite relational vocabulary with maximal arity 3 and T is a supersimple V-theory with elimination of quantifiers, then T has trivial dependence and finite SU-rank. This immediately gives the following strengthening of [18, Theorem 4.1]: if M is a ternary simple homogeneous structure with only finitely many constraints, then Th(M) has trivial dependence and finite SU-rank. (C) 2019 Published by Elsevier B.V.

关键词： Acceptance-rejection algorithm   Bayesian analysis   General incomplete categorical data   Minorization-maximization algorithm   Mode-sharing method  

摘要： Incomplete categorical data often occur in the fields such as biomedicine, epidemiology, psychology, sports and so on. In this paper, we first introduce a novel minorization-maximization (MM) algorithm to calculate the maximum likelihood estimates (MLEs) of parameters and the posterior modes for the analysis of general incomplete categorical data. Although the data augmentation (DA) algorithm and Gibbs sampling as the corresponding stochastic counterparts of the expectation-maximization (EM) and ECM algorithms are developed very well, up to now, little work has been done on creating stochastic versions to the existing MM algorithms. This is the first paper to propose a mode-sharing method in Bayesian computation for general incomplete categorical data by developing a new acceptance-rejection (AR) algorithm aided with the proposed MM algorithm. The key idea is to construct a class of envelope densities indexed by a working parameter and to identify a specific envelope density which can overcome the four drawbacks associated with the traditional AR algorithm. The proposed mode-sharing based AR algorithm has three significant characteristics: (I) it can automatically establish a family of envelope densities {g(lambda)(.): lambda is an element of S-lambda} indexed by a working parameter lambda, where each member in the family shares mode with the posterior density;(II) with the onedimensional grid method searching over the finite interval S-lambda,S- it can identify an optimal working parameter lambda(opt) by maximizing the theoretical acceptance probability, yielding a best easy-sampling envelope density g lambda(opt) (.), which is more dispersive than the posterior density;(III) it can obtain the optimal envelope constant c(opt) by using the mode-sharing theorem (indicating that the high-dimensional optimization can be completely avoided) or by using the proposed MM algorithm again. Finally, a toy model and three real data sets are used to illustrate the proposed meth

关键词： Extension subcategory   faltings' local-global principle   local cohomology module  

摘要： Faltings presented the local-global principle for the finiteness dimension of local cohomology modules. This paper deals with the local-global principle for an extension subcategory over a commutative Noetherian ring. We prove that finitely generated modules satisfy the local-global principles for certain extension subcategories. Additionally, we provide a generalization of Faltings' local-global principle, which also includes the localglobal principles for the Artinianness and Minimaxness of local cohomology modules.

关键词： Complexes   Projective   Strong global dimension   Derived bounded category   Degrees  

摘要： We prove that if the strong global dimension eta of an algebra A is finite, then C eta+1(proj A) is of finite type if and only if for each n >= 2, C-n(proj A) is of finite type. Moreover, we also prove some implications in order to know if for some positive integer is C-n(proj A) of infinite type. We determine the strong global dimension of some piecewise hereditary finite dimensional algebras taking into account their ordinary quivers with relations.