Automated Search for Good Coverage Criteria: Moving from Code Coverage to Fault Coverage Through Search-Based Software Engineering

We propose to use Search-Based Software Engineering to automatically evolve coverage criteria that are well correlated with fault revelation, through the use of existing fault databases. We explain how problems of bloat and overfitting can be ameliorated in our approach, and show how this new method will yield insight into faults — as well as better guidance for Search-Based Software Testing

An empirical study on the use of defect prediction for test case prioritization

Test case prioritization has been extensively re-searched as a means for reducing the time taken to discover regressions in software. While many different strategies have been developed and evaluated, prior experiments have shown them to not be effective at prioritizing test suites to find real faults. This paper presents a test case prioritization strategy based on defect prediction, a technique that analyzes code features - such as the number of revisions and authors - to estimate the likelihood that any given Java class will contain a bug. Intuitively, if defect prediction can accurately predict the class that is most likely to be buggy, a tool can prioritize tests to rapidly detect the defects in that class. We investigated how to configure a defect prediction tool, called Schwa, to maximize the likelihood of an accurate prediction, surfacing the link between perfect defect prediction and test case prioritization effectiveness. Using 6 real-world Java programs containing 395 real faults, we conducted an empirical evaluation comparing this paper's strategy, called G-clef, against eight existing test case prioritization strategies. The experiments reveal that using defect prediction to prioritize test cases reduces the number of test cases required to find a fault by on average 9.48% when compared with existing coverage-based strategies, and 10.4% when compared with existing history-based strategies

Sequences, sequence clusters and bacterial species

Whatever else they should share, strains of bacteria assigned to the same species should have house-keeping genes that are similar in sequence. Single gene sequences (or rRNA gene sequences) have very few informative sites to resolve the strains of closely related species, and relationships among similar species may be confounded by interspecies recombination. A more promising approach (multilocus sequence analysis, MLSA) is to concatenate the sequences of multiple house-keeping loci and to observe the patterns of clustering among large populations of strains of closely related named bacterial species. Recent studies have shown that large populations can be resolved into non-overlapping sequence clusters that agree well with species assigned by the standard microbiological methods. The use of clustering patterns to inform the division of closely related populations into species has many advantages for poorly studied bacteria (or to re-evaluate well-studied species), as it provides a way of recognizing natural discontinuities in the distribution of similar genotypes. Clustering patterns can be used by expert groups as the basis of a pragmatic approach to assigning species, taking into account whatever additional data are available (e.g. similarities in ecology, phenotype and gene content). The development of large MLSA Internet databases provides the ability to assign new strains to previously defined species clusters and an electronic taxonomy. The advantages and problems in using sequence clusters as the basis of species assignments are discussed

The impact of social impact bond financing

Social impact bonds (SIBs), also known as Pay for Success, are an innovation in Payment by Results contracting. Investors finance programs and are repaid based on the “SIB effect,” which includes changes in outcomes attributable to financing. We generate a quantitative estimate of this part of the SIB effect for two active labor market programs in the Netherlands and Switzerland. Comparing program impacts within providers using SIB and non-SIB contracts suggests financing has positive impacts on public benefit receipt, employment, and income. Qualitative research suggests this is because SIB contracts increased pressure for all involved parties, leading to the institutionalization of selection and greater resources for SIB-financed services. Contracts with high pressure, like SIBs, may compromise both performance requirements and the potential to measure performance. We examine the implications of these findings in relation to agency and stewardship theories and highlight the significance of SIBs as multilateral as opposed to bilateral contracts

Theory of periodic swarming of bacteria: application to Proteus mirabilis

The periodic swarming of bacteria is one of the simplest examples for pattern formation produced by the self-organized collective behavior of a large number of organisms. In the spectacular colonies of Proteus mirabilis (the most common species exhibiting this type of growth) a series of concentric rings are developed as the bacteria multiply and swarm following a scenario periodically repeating itself. We have developed a theoretical description for this process in order to get a deeper insight into some of the typical processes governing the phenomena in systems of many interacting living units. All of our theoretical results are in excellent quantitative agreement with the complete set of available observations.Comment: 11 pages, 8 figure

Nonequilibrium relaxation in neutral BCS superconductors: Ginzburg-Landau approach with Landau damping in real time

We present a field-theoretical method to obtain consistently the equations of motion for small amplitude fluctuations of the order parameter directly in real time for a homogeneous, neutral BCS superconductor. This method allows to study the nonequilibrium relaxation of the order parameter as an initial value problem. We obtain the Ward identities and the effective actions for small phase the amplitude fluctuations to one-loop order. Focusing on the long-wavelength, low-frequency limit near the critical point, we obtain the time-dependent Ginzburg-Landau effective action to one-loop order, which is nonlocal as a consequence of Landau damping. The nonequilibrium relaxation of the phase and amplitude fluctuations is studied directly in real time. The long-wavelength phase fluctuation (Bogoliubov-Anderson-Goldstone mode) is overdamped by Landau damping and the relaxation time scale diverges at the critical point, revealing critical slowing down.Comment: 31 pages 14 figs, revised version, to appear in Phys. Rev.

Transmission of New Bovine Prion to Mice

We previously reported that cattle were affected by a prion disorder that differed from bovine spongiform encephalopathy (BSE) by showing distinct molecular features of disease-associated protease-resistant prion protein (PrPres). We show that intracerebral injection of such isolates into C57BL/6 mice produces a disease with preservation of PrPres molecular features distinct from BSE

Renormalization of composite operators

The blocked composite operators are defined in the one-component Euclidean scalar field theory, and shown to generate a linear transformation of the operators, the operator mixing. This transformation allows us to introduce the parallel transport of the operators along the RG trajectory. The connection on this one-dimensional manifold governs the scale evolution of the operator mixing. It is shown that the solution of the eigenvalue problem of the connection gives the various scaling regimes and the relevant operators there. The relation to perturbative renormalization is also discussed in the framework of the $\phi^3$ theory in dimension $d=6$.Comment: 24 pages, revtex (accepted by Phys. Rev. D), changes in introduction and summar

Grain Surface Models and Data for Astrochemistry

AbstractThe cross-disciplinary field of astrochemistry exists to understand the formation, destruction, and survival of molecules in astrophysical environments. Molecules in space are synthesized via a large variety of gas-phase reactions, and reactions on dust-grain surfaces, where the surface acts as a catalyst. A broad consensus has been reached in the astrochemistry community on how to suitably treat gas-phase processes in models, and also on how to present the necessary reaction data in databases; however, no such consensus has yet been reached for grain-surface processes. A team of ∼25 experts covering observational, laboratory and theoretical (astro)chemistry met in summer of 2014 at the Lorentz Center in Leiden with the aim to provide solutions for this problem and to review the current state-of-the-art of grain surface models, both in terms of technical implementation into models as well as the most up-to-date information available from experiments and chemical computations. This review builds on the results of this workshop and gives an outlook for future directions

Does It Really Work? Re-Assessing the Impact of Pre-Departure Cross-Cultural Training on Expatriate Adjustment

Cultural adjustment is considered to be a prerequisite for expatriate success abroad. One way to enhance adjustment is to provide employees with knowledge and awareness of appropriate norms and behaviors of the host country through cross-cultural training (CCT). This article analyzes the impact of pre-departure CCT on expatriate adjustment and focuses on variations in participation, length and the comprehensiveness of training. Unlike previous research, the study focuses on the effectiveness of pre-departure CCT for non-US employees expatriated to a broad range of host country settings. Employing data from 339 expatriates from 20 German Multinational Corporations (MNCs) the study finds CCT has little if any effect on general, interactional or work setting expatriate adjustment. However, a significant impact of foreign language competence was found for all three dimensions of expatriate adjustment. We used interviews with 20 expatriates to supplement our discussion and provide further implications for practice