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关键词： Category of diagonals   Cluster category   Cluster algebra   Poset of type A   Socle-projective representation   Auslander Reiten quiver  

摘要： This paper establishes a link between the theory of cluster algebras and the theory of representations of partially ordered sets. We introduce a class of posets by requiring avoidance of certain types of peak-subposets and show that these posets can be realized as the posets of quivers of type Awith certain additional arrows. This class of posets is therefore called posets of type A. We then give a geometric realization of the category of finitely generated socle-projective modules over the incidence algebra of a poset of type A as a combinatorial category of certain diagonals of a regular polygon. This construction is inspired by the realization of the cluster category of type A as the category of all diagonals by Caldero, Chapoton and the first author [10]. We also study the subalgebra of the cluster algebra generated by those cluster variables that correspond to the socle-projectives under the above construction. We give a sufficient condition for when this subalgebra is equal to the whole cluster algebra. (C) 2020 Elsevier B.V. All rights reserved.

关键词： bush encroachment   community perception   land degradation   Namibia   vegetation structure  

摘要： Land degradation has put the world's rangelands under intense pressure and reduced their capacity to provide vital services to those who solely depend on them for survival. With the current pressures on rangelands, worldwide, there is an urgent need to survey the present condition of rangelands. Such detailed surveys can identify where improvement programmes can be emphasised;whether it be reseeding, stock control, sociological restraints or other actions. To combat rangeland degradation, management systems are more effective when they account for community perceptions and practices. This study aims to assess the current status of woody plants in different categories of degradation as perceived by herders in Kunene, Namibia. Furthermore, we wished to compare the perception of degradation by herders with the measured ecological condition. With the help of herders, sites representing different categories of degradation (low, moderate, high and protected) were identified and 10 plots of 400m(2)each were established in each category. Species diversity, density, basal area and regeneration of woody plants increased sequentially along the degradation gradient (high to low). Vegetation attributes such as species diversity, seedling density and standing basal area increased with increasing distances from the villages. Although the herders' perception of degradation, for high and moderate degradation, matches the ecological results, the low degradation sites show signs of bush encroachment, a type of degradation that the herders did not perceive as *** mopane, a known encroacher species across Namibia, was the dominant species in the moderate and low degradation ***-loeschea leubnitziae, which is also known to be an indicator of degradation, was the dominant species in the high degradation sites. The findings highlight the present and future threats the study area is facing and form the basis for current restoration research.

关键词： chronic inflammation   Genomic Prostate Score   molecular classifier score   nuclear polarization   OncotypeDx   stromal reaction  

摘要： Background For biopsies with Gleason 3 + 3 = 6 or 3 + 4 = 7 prostate cancer, the Genomic Prostate Score (GPS;OncotypeDx) is designed to predict severe pathology at prostatectomy, and, in some cases, recommends reclassification of the National Comprehensive Cancer Network (NCCN) risk category. We hypothesized that certain histopathologic features that were not considered in the original design of the assay actually would be associated with the NCCN risk category change indicated by GPS testing. Methods For patients with recommended NCCN risk category change, the biopsy cores used for GPS were re-reviewed for stromal reaction, chronic inflammation, and tumor nuclear polarization. Results Of 520 patients from May 2011 to December 2018, GPS testing suggested NCCN risk reclassification in 131 (25%);127 of these slides were available. Of these, the NCCN risk category increased from intermediate to high in 8, low to intermediate in 15, very low to low in 1, and decreased from intermediate to low in 32, and low to very low in 71. Biopsies with NCCN risk increase were associated with moderate or severe stromal reaction (p < .001) and chronic inflammation (p < .001);biopsies with NCCN risk decrease were associated with absence of these features. In Gleason 3 + 3 = 6 cases (n = 93), presence of nuclear polarization was associated with NCCN risk decrease and its absence with increase (p < .001). Conclusions Moderate or severe stromal reaction, chronic inflammation, and lack of nuclear polarization in Gleason score 3 + 3 = 6 tumors were each associated with an increase in NCCN risk category indicated by GPS and vice versa. Our results suggest that GPS captures histologic features associated with aggressiveness that are not routinely assessed in standard histopathologic assessments, and that consideration of such histologic features may improve upon current tumor grading approaches.

关键词： Copula   Gamma distribution   Biomarker   Sensitivity   Specificity   AUC  

摘要： Classification of a disease often depends on more than one test, and the tests can be interrelated. Under the incorrect assumption of independence, the test result using dependent biomarkers can lead to a conflicting disease classification. We develop a copula-based method for this purpose that takes dependency into account and leads to a unique decision. We first construct the joint probability distribution of the biomarkers considering Frank's, Clayton's and Gumbel's copulas. We then develop the classification method and perform a comprehensive simulation. Using simulated data sets, we study the statistical properties of joint probability distributions and determine the joint threshold with maximum classification accuracy. Our simulation study results show that parameter estimates for the copula-based bivariate distributions are not biased. We observe that the thresholds for disease classification converge to a stationary distribution across different choices of copulas. We also observe that the classification accuracy decreases with the increasing value of the dependence parameter of the copulas. Finally, we illustrate our method with a real data example, where we identify the joint threshold of Apolipoprotein B to Apolipoprotein A1 ratio and total cholesterol to high-density lipoprotein ratio for the classification of myocardial infarction. We conclude, the copula-based method works well in identifying the joint threshold of two dependent biomarkers for an outcome classification. Our method is flexible and allows modeling broad classes of bivariate distributions that take dependency into account. The threshold may allow clinicians to classify uniquely individuals at risk of developing the disease and plan for early intervention.

关键词： Gustave roussy immune score   Non-small-cell lung cancer   Video-assisted thoracoscopic surgery   Prognosis  

摘要： Backgrounds: The Gustave Roussy Immune score (GRIm-Score) emerges as a novel prognostic scoring system for patient selection in phase I trials testing targeted immunotherapy for advanced-stage cancer. We tried to assess potential prognostic roles of preoperative GRIm-Score in patients undergoing video-assisted thoracoscopic surgery (VATS) lobectomy for stage I-II non-small-cell lung cancer (NSCLC) by propensity score-matching (PSM) analysis. Methods: This PSM-based analysis was performed on our single-center prospectively-maintained database between January 2014 and October 2015. A Kaplan-Meier survival analysis using the log-rank test was used to distinguish differences in both overall survival (OS) and disease-free survival (DFS) between the patients stratified by preoperative GRIm-Score. Multivariable Cox-proportional hazards regression analysis and PSM analysis were both carried out to determine the final independent prognostic parameters. Results: There were 405 patients with surgically resectable stage I-II NSCLC included. Both OS and DFS were significantly shortened along with each number increase in the GRIm-Score group, showing a step-wise fashion. Such strong correlations between preoperative GRIm-Score estimated by a modified 3-category risk scale and survival outcomes still remained validated after PSM analysis. In addition, this GRIm-Score held the superior discriminatory power for predicting both OS and DFS to the other peripheral blood biomarkers. Multivariable analyses on the entire cohort and the PSM cohort demonstrated that GRIm-Score based on a 3-category risk assessment scale could be independently predictive of both OS and DFS. Conclusions: The GRIm-Score tool can also serve as an effective and noninvasive marker to optimize prognostic prediction for surgically resectable stage I-II NSCLC.

关键词： Race   Skin color   Social inequality   Caribbean   Jamaica  

摘要： Jamaica's social inequality is primarily held to be class-based due, in part, to the country's perceived ethno-racial homogeneity and to the particularities of its colonial past. However, whether "race" also systemically shapes inequality in Jamaica remains understudied. To address this empirical lacuna, I examine the effects of two measures of race-categorical race and skin color-on years of schooling and household amenities using data from the 2014 AmericasBarometer social survey. I find that access to household amenities and years of schooling are starkly structured by racial category, and even more robustly by skin color, across all dimensions. The findings challenge long-held assumptions that marginalize race with regards to social inequality in Jamaica. They also suggest the importance of a multidimensional approach to studying the effects of race for understanding stratification dynamics in Jamaica. As an English-speaking, majority Afro-descent society in the Caribbean, the study's findings add a unique country case for comparison to Latin America and may also speak to other similar contexts in the region.

关键词： discrete stochastic process   generalized logit models   multinomial distribution   tests for stationarity  

摘要： Transition models are an important framework that can be used to model longitudinal categorical data. They are particularly useful when the primary interest is in prediction. The available methods for this class of models are suitable for the cases in which responses are recorded individually over time. However, in many areas, it is common for categorical data to be recorded as groups, that is, different categories with a number of individuals in each. As motivation we consider a study in insect movement and another in pig behaviou. The first study was developed to understand the movement patterns of female adults ofDiaphorina citri, a pest of citrus plantations. The second study investigated how hogs behaved under the influence of environmental enrichment. In both studies, the number of individuals in different response categories was observed over time. We propose a new framework for considering the time dependence in the linear predictor of a generalized logit transition model using a quantitative response, corresponding to the number of individuals in each category. We use maximum likelihood estimation and present the results of the fitted models under stationarity and non-stationarity assumptions, and use recently proposed tests to assess non-stationarity. We evaluated the performance of the proposed model using simulation studies under different scenarios, and concluded that our modeling framework represents a flexible alternative to analyze grouped longitudinal categorical data.

关键词： decelerations   fetal monitoring   intrauterine resuscitation  

摘要： BACKGROUND: Maternal oxygen administration is a widely used intrauterine resuscitation technique for fetuses with category II electronic fetal monitoring patterns, despite a paucity of evidence on its ability to improve electronic fetal monitoring patterns. OBJECTIVE: This study investigated the effect of intrapartum oxygen administration on Category II electronic fetal monitoring patterns. STUDY DESIGN: This is a secondary analysis of a randomized trial conducted in 2016-2017, in which patients with fetuses at >= 37 weeks' gestation in active labor with category II electronic fetal monitoring patterns were assigned to 10 L/min of oxygen by face mask or room air until delivery. Trained obstetrical research nurses blinded to allocation extracted electronic fetal monitoring data. The primary outcome was a composite of high-risk category II features including recurrent variable decelerations, recurrent late decelerations, prolonged decelerations, tachycardia, or minimal variability 60 minutes after randomization to room air or oxygen. Secondary outcomes included individual components of the composite high-risk category II features, resolution of recurrent decelerations within 60 minutes of randomization, and total deceleration area. The outcomes between the room air and oxygen groups were compared using univariable statistics. Time-to-event analysis was used to compare time to resolution of recurrent decelerations between the groups. Paired analysis was used to compare the pre- and postrandomization outcomes within each group. RESULTS: All 114 randomized patients (57 roomair and 57 oxygen) were included in this analysis. There was no difference in resolution of recurrent decelerations within 60 minutes between the oxygen and room air groups (75.4% vs 86.0%;P=.15). The room air and oxygen groups had similar rates of composite high-risk category II features including recurrent variable decelerations, recurrent late decelerations, prolonged decelerations, tachycardia, and

关键词： Weighted projective line   Derived category   T-structure   Derived equivalence  

摘要： We use recollement and HRS-tilt to describe bounded t-structures on the bounded derived category D-b(X) of coherent sheaves over a weighted projective line X of domestic or tubular type. We will see from our description that the combinatorics in the classification of bounded t-structures on D-b(X) can be reduced to that in the classification of bounded t-structures on the bounded derived categories of finite dimensional right modules over representation-finite finite dimensional hereditary algebras.

关键词： Generative adversarial network (GAN)   Image-to-image translation   Attention   Clothes generation  

摘要： During the past decades, applying deep learning technologies on fashion industry are increasingly the mainstream. Due to the different gesture, illumination or self-occasion, it is hard to directly utilize the clothes images in real-world applications. In this paper, to handle this problem, we present a novel multi-stage, category-supervised attention-based conditional generative adversarial network by generating clear and detailed tiled clothing images from certain model images. This newly proposed method consists of two stages: in the first stage, we generate the coarse image which contains general appearance information (such as color and shape) and category of the garment, where a spatial transformation module is utilized to handle the shape changes during image synthesis and an additional classifier is employed to guide coarse image generated in a category-supervised manner;in the second stage, we propose a dual path attention-based model to generate the fine-tuned image, which combines the appearance information of the coarse result with the high-frequency information of the model image. In detail, we introduce the channel attention mechanism to assign weights to the information of different channels instead of connecting directly. Then, a self-attention module is employed to model long-range correlation making the generated image close to the target. In additional to the framework, we also create a person-to-clothing data set containing 10 categories of clothing, which includes more than 34 thousand pairs of images with category attribute. Extensive simulations are conducted, and experimental result on the data set demonstrates the feasibility and superiority of the proposed networks.