Topic supervised non-negative matrix factorization

Topic models have been extensively used to organize and interpret the contents of large, unstructured corpora of text documents. Although topic models often perform well on traditional training vs. test set evaluations, it is often the case that the results of a topic model do not align with human interpretation. This interpretability fallacy is largely due to the unsupervised nature of topic models, which prohibits any user guidance on the results of a model. In this paper, we introduce a semi-supervised method called topic supervised non-negative matrix factorization (TS-NMF) that enables the user to provide labeled example documents to promote the discovery of more meaningful semantic structure of a corpus. In this way, the results of TS-NMF better match the intuition and desired labeling of the user. The core of TS-NMF relies on solving a non-convex optimization problem for which we derive an iterative algorithm that is shown to be monotonic and convergent to a local optimum. We demonstrate the practical utility of TS-NMF on the Reuters and PubMed corpora, and find that TS-NMF is especially useful for conceptual or broad topics, where topic key terms are not well understood. Although identifying an optimal latent structure for the data is not a primary objective of the proposed approach, we find that TS-NMF achieves higher weighted Jaccard similarity scores than the contemporary methods, (unsupervised) NMF and latent Dirichlet allocation, at supervision rates as low as 10% to 20%

Black Holes and Galactic Density Cusps Spherically Symmetric Anisotropic Cusps

Aims: In this paper we study density cusps that may contain central black holes. The actual co-eval self-similar growth would not distinguish between the central object and the surroundings. Methods: To study the environment of a growing black hole we seek descriptions of steady `cusps' that may contain a black hole and that retain at least a memory of self-similarity. We refer to the environment in brief as the `bulge' and on smaller scales, the `halo'. Results: We find simple descriptions of the simulations of collisionless matter by comparing predicted densities, velocity dispersions and distribution functions with the simulations. In some cases central point masses may be included by iteration. We emphasize that the co-eval self-similar growth allows an explanation of the black hole bulge mass correlation between approximately similar collisionless systems. Conclusions: We have derived our results from first principles assuming adiabatic self-similarity and either self-similar virialisation or normal steady virialisation. We conclude that distribution functions that retain a memory of self-similar evolution provide an understanding of collisionless systems. The implied energy relaxation of the collisionless matter is due to the time dependence. Phase mixing relaxation may be enhanced by clump-clump interactions.Comment: 9 pp, 3 figs, accepted by A\&

The role of non-canonical Wnt/planar cell polarity signalling in breast cancer progression

The role of planar cell polarity (PCP) signalling in breast cancer is unclear, as evidence shows that activation of this pathway with WNT5A can either promote or inhibit progression. Using the 21T cells, which represent distinct stages of breast cancer progression when grown in a mouse xenograft model (21PT, atypical ductal hyperplasia; 21NT ductal carcinoma in situ; 21MT-1, invasive mammary carcinoma), I hypothesized that WNT5A will promote progression only when VANGL1, another component of PCP signalling, is elevated. Each 21T cell line showed distinct stage-specific morphologies when grown in a Matrigel “on-top” assay. WNT5A overexpression promoted progression to an invasive phenotype in 21NT (ductal carcinoma in situ-like) cells that was partially dependent on RHOA, but not in 21PT (atypical ductal hyperplasia-like) cells. VANGL1 overexpression alone or with recombinant Wnt5a increased migration but had no effect on invasion in 21PT cells. Finally, knockdown of WNT5A and VANGL1 separately did not change morphology of 21MT-1 (invasive, metastatic) cells; however, WNT5A knockdown was incomplete. PCP signalling likely plays a role in promoting progression to an invasive phenotype but this may be independent of high VANGL1 expression

Nimbus-7 Scanning Multichannel Microwave Radiometer (SMMR) PARM tape user's guide

The Scanning Multichannel Microwave Radiometer (SMMR) instrument, onboard the Nimbus-7 spacecraft, collected data from Oct. 1978 until Jun. 1986. The data were processed to physical parameter level products. Geophysical parameters retrieved include the following: sea-surface temperatures, sea-surface windspeed, total column water vapor, and sea-ice parameters. These products are stored on PARM-LO, PARM-SS, and PARM-30 tapes. The geophysical parameter retrieval algorithms and the quality of these products are described for the period between Nov. 1978 and Oct 1985. Additionally, data formats and data availability are included

Getting everyone on the same page : A staff focus group study for library web site redesign

Purpose - Using staff focus groups in the redevelopment of a library web site deploys their knowledge of user navigation issues and search strategies and addresses the unique needs of library staff. This paper seeks to describe the process of planning, recruiting, and conducting staff focus groups and provide a discussion of lessons learned. Design/methodology/approach - A committee of professionals and non-professionals from the University of Calgary Library conducted a series of five focus groups with library staff. The goals were to determine their content and service priorities for the redesigned library web site, and also to ensure that staff was included in the redesign process. Findings - This paper makes recommendations for library staff focus group interviewing, including planning, formulating questions, recruitment, conducting sessions, and analysis and reporting. Practical implications - Focus group interviews can be effectively conducted in-house, with careful planning and adherence to established guidelines. Focus groups are a very useful method for gathering staff input for web site redesign or any other library-planning project. Originality/value - This paper will be useful to librarians interested in assessing staff needs and priorities through focus group interviews. The paper fills a void in the library literature regarding the use of library staff as both focus group leaders and participants

Black holes and Galactic density cusps -- I. Radial orbit cusps and bulges

In this paper, we study the distribution functions that arise naturally during self-similar radial infall of collisionless matter. Such matter may be thought of either as stars or as dark matter particles. If a rigorous steady state is assumed, then the system is infinite and is described by a universal distribution function given the self-similar index. The steady logarithmic potential case is exceptional and yields the familiar Gaussian for an infinite system with an inverse-square density profile. We show subsequently that for time-dependent radial self-similar infall, the logarithmic case is accurately described by the Fridmann and Polyachenko distribution function. The system in this case is finite but growing. We are able to embed a central mass in the universal steady distribution only by iteration, except in the case of massless particles. The iteration yields logarithmic corrections to the massless particle case and requires a `renormalization' of the central mass. A central spherical mass may be accurately embedded in the Fridmann and Polyachenko growing distribution however. Some speculation is given concerning the importance of radial collisionless infall in actual galaxy formation.Comment: 10 pp, 3 fig

Enantioselective Organocatalytic α-Fluorination of Aldehydes

The first direct enantioselective catalytic α-fluorination of aldehydes has been accomplished. The use of enamine catalysis has provided a new organocatalytic strategy for the enantioselective fluorination of aldehydes to generate α-fluoro aldehydes, an important chiral synthon for medicinal agent synthesis. The use of imidazolidinone 1 as the asymmetric catalyst has been found to mediate the fluorination of a large variety of aldehyde substrates with N-fluorobenzenesulfonimide serving as the electrophilic source of fluorine. A diverse spectrum of aldehyde substrates can also be accommodated in this new organocatalytic transformation. While catalyst quantities of 20 mol % were generally employed in this study, successful halogenation can be accomplished using catalyst loadings as low as 2.5 mol %

Comparative study of design: application to Engineering Design

A recent exploratory study examines design processes across domains and compares them. This is achieved through a series of interdisciplinary, participative workshops. A systematic framework is used to collect data from expert witnesses who are practising designers across domains from engineering through architecture to product design and fashion, including film production, pharmaceutical drugs, food, packaging, graphics and multimedia and software. Similarities and differences across domains are described which indicate the types of comparative analysis we have been able to do from our data. The paper goes further and speculates on possible lessons for selected areas of engineering design which can be drawn from comparison with processes in other domains. As such this comparative design study offers the potential for improving engineering design processes. More generally it is a first step in creating a discipline of comparative design which aims to provide a new rich picture of design processes