1,720,980 research outputs found
Thermoregulated gas transport through electrospun nanofiber membranes
No full textThermoregulation of gas transport using electrospun fiber membranes is demonstrated experimentally for the first time. The fiber membranes comprise three layers: a middle layer of electrospun polystyrene sandwiched between two outer layers of electrospun cellulose acetate mat as supports, bonded together by hot pressing. The electrospun polystyrene layer serves as a phase change material that blocks transport of gases though the membrane when the fibers de-vitrify. The membrane exhibited a reduction in oxygen flux at temperatures in excess of 140 °C. Using a blend of polysulfone and polystyrene resulted in an upward shift of the transition temperature to 250 °C. Modeling of transport was performed to estimate the impact of the morphological properties of the membranes such as tortuosity, fiber diameter, and porosity.Philip Morris Internationa
Sparse ordinal discriminant analysis
No full textOrdinal class labels are frequently observed in classification studies across various fields. In medical science, patients' responses to a drug can be arranged in the natural order, reflecting their recovery postdrug administration. The severity of the disease is often recorded using an ordinal scale, such as cancer grades or tumor stages. We propose a method based on the linear discriminant analysis (LDA) that generates a sparse, low-dimensional discriminant subspace reflecting the class orders. Unlike existing approaches that focus on predictors marginally associated with ordinal labels, our proposed method selects variables that collectively contribute to the ordinal labels. We employ the optimal scoring approach for LDA as a regularization framework, applying an ordinality penalty to the optimal scores and a sparsity penalty to the coefficients for the predictors. We demonstrate the effectiveness of our approach using a glioma dataset, where we predict cancer grades based on gene expression. A simulation study with various settings validates the competitiveness of our classification performance and demonstrates the advantages of our approach in terms of the interpretability of the estimated classifier with respect to the ordinal class labels.
Variable Selection and Basis Learning for Ordinal Classification
No full textWe propose a method for variable selection and basis learning for high-dimensional classification with ordinal responses. The proposed method extends sparse multiclass linear discriminant analysis, with the aim of identifying not only the variables relevant to discrimination but also the variables that are order-concordant with the responses. For this purpose, we compute for each variable an ordinal weight, where larger weights are given to variables with ordered group-means, and penalize the variables with smaller weights more severely. A two-step construction for ordinal weights is developed, and we show that the ordinal weights correctly separate ordinal variables from non-ordinal variables with high probability. The resulting sparse ordinal basis learning method is shown to consistently select either the discriminant variables or the ordinal and discriminant variables, depending on the choice of a tunable parameter. Such asymptotic guarantees are given under a high-dimensional asymptotic regime where the dimension grows much faster than the sample size. We also discuss a two-step procedure of post-screening ordinal variables among the selected discriminant variables. Simulated and real data analyses confirm that the proposed basis learning provides sparse and interpretable basis, as it mostly consists of ordinal variables. Supplementary materials for this article are available online.
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
An Empirical Study of the Broken Window Theory
No full text본 연구는 환경설계를 통한 범죄예방(crime prevention through environmental design: CPTED)과 동네무질서, 범죄 두려움 그리고 사회적 자본의 관계를 실증적으로 분석하였다. 실증적 분석을 위하여 수도권의 다양한 지역에서 표본을 추출하여 구조방정식 모형을 추정하였다. 연구결과에 따르면 환경설계를 통한 범죄예방은 동네무질서를 감소시키고 감소된 동네무질서는 범죄 두려움을 줄이고 사회자본을 높이는 효과가 있는 것으로 나타났다. 그러나 기존 연구에서 중요한 변수로 지적된 지역 범죄통제 거버넌스는 이 분석에서 통계적인 의미가 없는 것으로 나타났다. 그럼에도 불구하고 범죄의 예방을 위한 물리적 환경의 강화는 범죄예방에 중요한 수단이며 동네무질서가 범죄의 중요한 요인이라는 깨진 유리창이론의 기본적인 주장은 실증적으로 입증되었다. 연구의 함 의로 방범환경설계와 지역 범죄통제 거버넌스를 강화시키기 위한 법･제도적 장치 마련, 지역공동체 이해관계자들의 의사결정참여를 활성화 할 수 있는 지역사회 차원의 거버넌스 모델의 구축 등을 제안하면서 연구를 마무리 하였다. Crime prevention has been recognized in recent years as a major challenge that governments must successfully deal with. Public administration has witnessed discussions on neighborhood disorder after facing the increasing trends of heinous crimes. This study empirically analyzes the Broken Window Theory that neighborhood disorder increases crime and decreases social capital. The present study also examines the effects of crime prevention through environmental design (CPTED). A survey of 706 residents in Seoul and Kyounggi area was conducted. The survey measured individual perceptions of CPTED, crime prevention governance, neighborhood disorder, crime, and social capital. The major findings of this study are that the effective CPTED tends to reduce neighborhood disorder and enhance social capital. The current problems and future directions of CPTED research and practices in the field of police administration are also pointed out.본 연구는 국토해양부가 주관하고 한국건설교통기술평가원이 시행하는 2007년도 첨단도시개발사업(과제번호:07도시재생B04) 지원사업으로 이루어진 것임
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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