Star Formation and Relaxation in 379 Nearby Galaxy Clusters

We investigate the relationship between star formation (SF) and level of relaxation in a sample of 379 galaxy clusters at z < 0.2. We use data from the Sloan Digital Sky Survey to measure cluster membership and level of relaxation, and to select star-forming galaxies based on mid-infrared emission detected with the Wide-Field Infrared Survey Explorer. For galaxies with absolute magnitudes M_r < -19.5, we find an inverse correlation between SF fraction and cluster relaxation: as a cluster becomes less relaxed, its SF fraction increases. Furthermore, in general, the subtracted SF fraction in all unrelaxed clusters (0.117 +/- 0.003) is higher than that in all relaxed clusters (0.097 +/- 0.005). We verify the validity of our SF calculation methods and membership criteria through analysis of previous work. Our results agree with previous findings that a weak correlation exists between cluster SF and dynamical state, possibly because unrelaxed clusters are less evolved relative to relaxed clusters.Comment: 6 pages, 4 figures, accepted for publication in Ap

To Innovate or Not to Innovate, That Is the Question: The Functions, Failures, and Foibles of the Reward Function Theory of Patent Law in Relation to Computer Software Platforms

The patent system has traditionally been viewed as having two primary functions: the reward function and the prospect function. Although these theories do explain some behavior which results from the practical applications of the patent system, they also overlook some behavior of the patent system which indicates a failure of these functions. In order to properly prevent such failure, this paper proposes that the patent system adopt an orientation that will lead to increased innovative rivalry and competition. In Part I, using the computer operating system software market as an example, I propose a framework for reconceptualizing patent protection as it applies to software operating system platforms. Part II briefly examines both the classical and neoclassical reward function and prospect function theories. Part III defines the innovation market and describes the market dynamics that create disincentives for innovation. These disincentives tend to limit the number of competitors in innovation markets and create conditions which reduce the effectiveness of the reward incentives to the extent that the reward function fails in its entirety. Part IV examines the resulting harms of this failure and identifies how reward function failure affects product markets, which are dependent upon the reward function. Part V discusses why the prospect function does not address the problems related to reward function failure and the reasons that the promotion of innovative rivalry would alleviate some of the problems. Part VI uses the relationship between computer programs to illustrate the shortcomings of the patent system\u27s inability to prevent the problems created by non-competitive innovation. This section also considers how the patent system might be better adjusted to prevent reward function failure. Lastly, Part VI also proposes a series of alternative frameworks for creating a competitively oriented approach to the application of the patent system in the case of computer software platforms

Star Formation and Substructure in Galaxy Clusters

We investigate the relationship between star formation (SF) and substructure in a sample of 107 nearby galaxy clusters using data from the Sloan Digital Sky Survey (SDSS). Several past studies of individual galaxy clusters have suggested that cluster mergers enhance cluster SF, while others find no such relationship. The SF fraction in multi-component clusters (0.228 +/- 0.007) is higher than that in single-component clusters (0.175 +/- 0.016) for galaxies with M^0.1_r < -20.5. In both single- and multi-component clusters, the fraction of star-forming galaxies increases with clustercentric distance and decreases with local galaxy number density, and multi-component clusters show a higher SF fraction than single-component clusters at almost all clustercentric distances and local densities. Comparing the SF fraction in individual clusters to several statistical measures of substructure, we find weak, but in most cases significant at greater than 2 sigma, correlations between substructure and SF fraction. These results could indicate that cluster mergers may cause weak but significant SF enhancement in clusters, or unrelaxed clusters exhibit slightly stronger SF due to their less evolved states relative to relaxed clusters.Comment: 10 pages, 6 figures, accepted for publication in Ap

ExplainIt! -- A declarative root-cause analysis engine for time series data (extended version)

We present ExplainIt!, a declarative, unsupervised root-cause analysis engine that uses time series monitoring data from large complex systems such as data centres. ExplainIt! empowers operators to succinctly specify a large number of causal hypotheses to search for causes of interesting events. ExplainIt! then ranks these hypotheses, reducing the number of causal dependencies from hundreds of thousands to a handful for human understanding. We show how a declarative language, such as SQL, can be effective in declaratively enumerating hypotheses that probe the structure of an unknown probabilistic graphical causal model of the underlying system. Our thesis is that databases are in a unique position to enable users to rapidly explore the possible causal mechanisms in data collected from diverse sources. We empirically demonstrate how ExplainIt! had helped us resolve over 30 performance issues in a commercial product since late 2014, of which we discuss a few cases in detail.Comment: SIGMOD Industry Track 201

Stent Scraping for Histology: An Alternative Method for Obtaining Tissue to Rule out Neoplasia

Despite improvement in diagnostic modalities, confirmation of a histologic diagnosis of cancer of the biliary tree and pancreas remains elusive. Attempts to collect positive cytology specimens from vigorous brushings or washings obtained at endoscopy or percutaneously are often unsuccessful. In our unit, we have increased the yield by obtaining tissue scraped from prostheses that have been previously placed in either the bile duct or the pancreatic duct. The stents are first flushed with saline to collect cytology specimens, after which, they are bisected and scraped, and these contents are prepared in a manner similar to that used to prepare biopsy samples. Twelve of 16 scraped samples, 9 bile duct and 3 pancreas, were positive for adenocarcinoma. The cytology specimens were positive in only 4 of the 12. We recommend this method of sampling from material contained within prostheses as an adjunct when previous brushings, washings, or biopsies are negative