Dynamic Race Prediction in Linear Time

Writing reliable concurrent software remains a huge challenge for today's programmers. Programmers rarely reason about their code by explicitly considering different possible inter-leavings of its execution. We consider the problem of detecting data races from individual executions in a sound manner. The classical approach to solving this problem has been to use Lamport's happens-before (HB) relation. Until now HB remains the only approach that runs in linear time. Previous efforts in improving over HB such as causally-precedes (CP) and maximal causal models fall short due to the fact that they are not implementable efficiently and hence have to compromise on their race detecting ability by limiting their techniques to bounded sized fragments of the execution. We present a new relation weak-causally-precedes (WCP) that is provably better than CP in terms of being able to detect more races, while still remaining sound. Moreover it admits a linear time algorithm which works on the entire execution without having to fragment it.Comment: 22 pages, 8 figures, 1 algorithm, 1 tabl

Using participatory design and visual narrative inquiry to investigate researchers’ data challenges and recommendations for library research data services

Purpose – The purpose of this paper is to report on an information gathering study on users’ research data-related challenges and proposals for library research data services (RDS). This study probes how early career researchers visually conceptualize the research process in their disciplines, their self-reported research data challenges, and their recommendations for library RDS. Design/methodology/approach – Two focus group sessions were undertaken with a total of eight early career researchers. Adopting the visual narrative inquiry method, the participants were asked to sketch the general research process in their domain. The individuals’ illustrations of the research process were then used as the basis for reflecting on their data-related needs and potential RDS that would assist them during the research process. Findings – Participants presented a research process that was more personal and, in most cases, more imperfect than the research lifecycle models that academic libraries are increasingly using for RDS development and communication. The authors present their data-related challenges, which included data access barriers, low knowledge of best practices for research data management, the need for a deeper understanding of post-publication impact, and inconsistent awareness of existing library and institution RDS. The authors outline RDS recommendations that participants proposed, which included a web-based tools, customized training sessions, and “distilled” guides to research data best practices. Practical implications – The study flagged users’ gaps in understandings of existing library and institutional RDS, suggesting that there may be an opportunity to engage users in the design of communications plans for services. The findings from this user study will inform the development of RDS at the institution. Originality/value – This paper puts forth a methodological approach that academic libraries can adapt for understanding users’ needs and user-generated design solutions

Defects in SiO2 as the possible origin of near interface traps in the SiC∕SiO2 system: A systematic theoretical study

A systematic study of the level positions of intrinsic and carbon defects in SiO2 is presented, based on density functional calculations with a hybrid functional in an alpha-quartz supercell. The results are analyzed from the point of view of the near interface traps (NIT), observed in both SiC/SiO2 and Si/SiO2 systems, and assumed to have their origins in the oxide. It is shown that the vacancies and the oxygen interstitial can be excluded as the origin of such NIT, while the silicon interstitial and carbon dimers give rise to gap levels in the energy range inferred from experiments. The properties of these defects are discussed in light of the knowledge about the SiC/SiO2 interface

Monocytes regulate the mechanism of T-cell death by inducing Fas-mediated apoptosis during bacterial infection.

Monocytes and T-cells are critical to the host response to acute bacterial infection but monocytes are primarily viewed as amplifying the inflammatory signal. The mechanisms of cell death regulating T-cell numbers at sites of infection are incompletely characterized. T-cell death in cultures of peripheral blood mononuclear cells (PBMC) showed 'classic' features of apoptosis following exposure to pneumococci. Conversely, purified CD3(+) T-cells cultured with pneumococci demonstrated necrosis with membrane permeabilization. The death of purified CD3(+) T-cells was not inhibited by necrostatin, but required the bacterial toxin pneumolysin. Apoptosis of CD3(+) T-cells in PBMC cultures required 'classical' CD14(+) monocytes, which enhanced T-cell activation. CD3(+) T-cell death was enhanced in HIV-seropositive individuals. Monocyte-mediated CD3(+) T-cell apoptotic death was Fas-dependent both in vitro and in vivo. In the early stages of the T-cell dependent host response to pneumococci reduced Fas ligand mediated T-cell apoptosis was associated with decreased bacterial clearance in the lung and increased bacteremia. In summary monocytes converted pathogen-associated necrosis into Fas-dependent apoptosis and regulated levels of activated T-cells at sites of acute bacterial infection. These changes were associated with enhanced bacterial clearance in the lung and reduced levels of invasive pneumococcal disease