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

A Family History of Lethal Prostate Cancer and Risk of Aggressive Prostate Cancer in Patients Undergoing Radical Prostatectomy.

We investigated whether a family history of lethal prostate cancer (PCa) was associated with high-risk disease or biochemical recurrence in patients undergoing radical prostatectomy. A cohort of radical prostatectomy patients was stratified into men with no family history of PCa (NFH); a first-degree relative with PCa (FH); and those with a first-degree relative who had died of PCa (FHD). Demographic, operative and pathologic outcomes were analyzed. Freedom from biochemical recurrence was examined using Kaplan-Meier log rank. A multivariate Cox logistic regression analysis was also performed. We analyzed 471 men who underwent radical prostatectomy at our institution with known family history. The three groups had: 355 patients (75%) in NFH; 97 patients (21%) in FH; and 19 patients (4%) in FHD. The prevalence of a Gleason score ≥8, higher pathologic T stage, and biochemical recurrence (BCR) rates did not significantly differ between groups. On Kaplan-Meier analysis there were no differences in short-term BCR rates (p = 0.212). In this cohort of patients undergoing radical prostatectomy, those with first-degree relatives who died of PCa did not have an increased likelihood of high-risk or aggressive PCa or shorter-term risk of BCR than those who did not

Searching for z ~ 6 Objects with the HST Advanced Camera for Surveys: Preliminary Analysis of a Deep Parallel Field

Recent results suggest that z ~ 6 marks the end of the reionization era. A large sample of objects at z ~ 6, therefore, will be of enormous importance, as it will enable us to observationally determine the exact epoch of the reionization and the sources that are responsible for it. With the HST Advanced Camera for Surveys (ACS) coming on line, we now have an unique opportunity to discover a significant number of objects at z ~ 6. The pure parallel mode implemented for the Wide Field Camera (WFC) has greatly enhanced this ability. We present our preliminary analysis of a deep ACS/WFC parallel field at |b|=74.4^o. We find 30 plausible z ~ 6 candidates, all of which have S/N > 7 in the F850LP-band. The major source of contamination could be faint Galactic cool dwarfs, and we estimated that they would contribute at most 4 objects to our candidate list. We derived the cumulative number density of galaxies at 6.0 <= z <= 6.5 as 2.3 arcmin^{-2} to a limit of 28.0 mag in the F850LP-band, which is slightly higher than our prediction. If this is not due to an underestimated contamination rate, it could possibly imply that the faint-end slope of the z ~ 6 luminosity function is steeper than alpha=-1.6. At the very least, our result suggests that galaxies with L<L^* do exist in significant number at z ~ 6 and they could be the major sources that contributed to the reionizing photons.Comment: accepted for publication in the ApJL; replaced with slightly modified versio

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

Endoscopic Retrograde Cholangiopancreatography Treatment of Cholecystitis: Possible? Yes; Practical??

Classically, until now, the management of cholecystitis has consisted of immediate and judicious clinical assessment of the affected patient, interpolating into the assessment of the physical findings and results from appropriate laboratory, x-ray, and scanning techniques (sonography and scintigraphy) to formulate a clinical impression. Usually, after the diagnosis has been established, the patient is subjected to a cholecystectomy, although the timing of the surgery may vary depending on the clinical condition of the patient. Alternatives to this management (cholecystectomy, medical management) scheme have been suggested, but these are dependent upon the clinical condition ofthe patient and considerations of risks. Percutaneous drainage of the gallbladder or cholecystostomy is sufficient enough to provide drainage, relieve obstruction, and the consequences of infection, i.e., sepsis, and prevent perforation. A contributory role of endoscopic retrograde cholangiopancreatography (ERCP) in this schema has not been a consideration. An ERCP is rarely employed for therapy (or diagnosis) when cholecystitis is suspected but it might assume a more significant role if it is considered an efficacious alternative in specific conditions. We have had the unusual experience of managing 11 patients with cholecystitis employing ERCP and its therapeutic modalities, i.e., sphincterotomy, selective cannulation of the cystic duct, and relieving obstruction of that structure by catheter displacement of an obstructing stone. Endoscopic techniques providing decompression of the gallbladder are described, and the feasibility of utilizing endoscopic procedures for treatment of cholecystitis will be given consideration