Case Study Of Phased Model For Software Change In A Multiple-Programmer Environment

The aim of this thesis is to perform an empirical study comparing programmers completing software changes assisted by the recently published software process Phased Model for Software Change (PMSC) to those completing software changes without any assistance. There have been numerous researches on software change, but most of them focused more on individual phases of the software change process in lieu of the software change process as a whole. For that reason, this thesis explores the impact of the PMSC process on programmers\u27 performance. The subjects of this study are graduate students with different level of experience. The results of the experiment show that following the PMSC process improves the performance of both less experienced and more experienced programmers by reducing the amount of time spent to complete software changes by about half. This improvement is noticeable in both code analysis and code implementation activities. We also talk about ways to refine PMSC

Period change of massive binaries from combined photometric and spectroscopic data in Cygnus OB2

Context. Mass loss is an important property in evolution models of massive stars. As up to 90% of the massive stars have a visual or spectroscopic companion and many of them exhibit mass exchange, mass-loss rates can be acquired through the period study of massive binaries. Aims. Using our own photometric observations as well as archival data, we look for variations in orbital periods of seven massive eclipsing binary systems in the Cygnus OB2 association and estimate their mass-loss rates and stellar parameters. Methods. We use a Bayesian parameter estimation method to simultaneously fit the period and period change to all available data and a stellar modelling tool to model the binary parameters from photometric and radial-velocity data. Results. Four out of the seven selected binaries show non-zero period change values at two-sigma confidence level. We also report for the first time the eclipsing nature of a star MT059.Comment: 12 pages, 18 figures, accepted for publication in A&

Critical Factors and Multisite Implementation of ERP: A Case Study in the UAE

Despite extensive studies in the ERP literature, little empirical understanding has been reached in relation to ERP implementation experiences in developing markets, particularly in the UAE context. Derived from the notions of critical successful factors and multisite implementation, two of widely researched areas in ERP studies, this paper thus seeks to provide practical insights about organizations’ ERP implementation experiences in the UAE setting. More specifically, it describes and contrasts critical factors and multisite implementation experiences in two case organizations situated in the UAE. These case organizations, one being categorized as a global company and the other local, provide interesting comparison of ERP implementation because of their complementary organizational structure and business strategies. In contrast to traditional ERP frameworks’ suggestions, these case organizations’ experiences reveal that contemporary ERP implementations might be more complex than previously expected since none of these case organizations’ ERP experiences follows suggestions made by frameworks based. Further discussion about how to better understand and examine maturing ERP technology in an increasingly globalized business environment such as the UAE is provided

Control theory for principled heap sizing

We propose a new, principled approach to adaptive heap sizing based on control theory. We review current state-of-the-art heap sizing mechanisms, as deployed in Jikes RVM and HotSpot. We then formulate heap sizing as a control problem, apply and tune a standard controller algorithm, and evaluate its performance on a set of well-known benchmarks. We find our controller adapts the heap size more responsively than existing mechanisms. This responsiveness allows tighter virtual machine memory footprints while preserving target application throughput, which is ideal for both embedded and utility computing domains. In short, we argue that formal, systematic approaches to memory management should be replacing ad-hoc heuristics as the discipline matures. Control-theoretic heap sizing is one such systematic approach

Does algorithmic trading improve liquidity?

Algorithmic trading has sharply increased over the past decade. Equity market liquidity has improved as well. Are the two trends related? For a recent five-year panel of New York Stock Exchange (NYSE) stocks, we use a normalized measure of electronic message traffic (order submissions, cancellations, and executions) as a proxy for algorithmic trading, and we trace the associations between liquidity and message traffic. Based on within-stock variation, we find that algorithmic trading and liquidity are positively related. To sort out causality, we use the start of autoquoting on the NYSE as an exogenous instrument for algorithmic trading. Previously, specialists were responsible for manually disseminating the inside quote. As stocks were phased in gradually during early 2003, the manual quote was replaced by a new automated quote whenever there was a change to the NYSE limit order book. This market structure change provides quicker feedback to traders and algorithms and results in more message traffic. For large-cap stocks in particular, quoted and effective spreads narrow under autoquote and adverse selection declines, indicating that algorithmic trading does causally improve liquidity

Similarities, challenges and opportunities of wikipedia content and open source projects

Copyright @ 2012 John Wiley & Sons, Ltd.Several years of research and evidence have demonstrated that Open Source Software (OSS) portals often contain a large amount of software projects that simply do not evolve, developed by relatively small communities, struggling to attract a sustained number of contributors. These portals have started to increasingly act as a storage for abandoned projects, and researchers and practitioners should try and point out how to take advantage of such content. Similarly, other online content portals (like Wikipedia) could be harvested for valuable content. In this paper we argue that, even with differences in the requested expertise, many projects reliant on content and contributions by users undergo a similar evolution, and follow similar patterns: when a project fails to attract contributors, it appears to be not evolving, or abandoned. Far from a negative finding, even those projects could provide valuable content that should be harvested and identified based on common characteristics: by using the attributes of “usefulness” and “modularity” we isolate valuable content in both Wikipedia pages and OSS projects

Thermal dosimetry for bladder hyperthermia treatment. An overview.

The urinary bladder is a fluid-filled organ. This makes, on the one hand, the internal surface of the bladder wall relatively easy to heat and ensures in most cases a relatively homogeneous temperature distribution; on the other hand the variable volume, organ motion, and moving fluid cause artefacts for most non-invasive thermometry methods, and require additional efforts in planning accurate thermal treatment of bladder cancer. We give an overview of the thermometry methods currently used and investigated for hyperthermia treatments of bladder cancer, and discuss their advantages and disadvantages within the context of the specific disease (muscle-invasive or non-muscle-invasive bladder cancer) and the heating technique used. The role of treatment simulation to determine the thermal dose delivered is also discussed. Generally speaking, invasive measurement methods are more accurate than non-invasive methods, but provide more limited spatial information; therefore, a combination of both is desirable, preferably supplemented by simulations. Current efforts at research and clinical centres continue to improve non-invasive thermometry methods and the reliability of treatment planning and control software. Due to the challenges in measuring temperature across the non-stationary bladder wall and surrounding tissues, more research is needed to increase our knowledge about the penetration depth and typical heating pattern of the various hyperthermia devices, in order to further improve treatments. The ability to better determine the delivered thermal dose will enable clinicians to investigate the optimal treatment parameters, and consequentially, to give better controlled, thus even more reliable and effective, thermal treatments

A Bounded Index Test to make Robust Heterogeneous Welfare Comparisons

During last decade, improved macroeconomic and budgetary conditions have allowed for fiscal reforms in several EU countries. The main aim behind personal income tax reforms across Europe has been to reduce the tax burden on labour and to encourage work – especially for less productive workers. In this context, Anglo Saxon countries and more recently Continental European countries, including Belgium, have shown increasing interest in tax-benefit instruments awarding monetary transfers or tax reductions, conditional on employment. Using a discrete hours labour supply model, this paper assesses the impact of the 2001 Belgian Tax Reform on female labour supply. Results suggest that labour supply responses are moderate but significant by international standards. Yet, due to an uneven calibration of tax rebates and in-works benefits, the potential labour supply responses are rather dispersed over the whole range of the income distribution. Consequently, the gains from the reform do not appear to be evenly distributed across taxpayers.