Verification and Enforcement of Safe Schedules for Concurrent Programs

Automated software verification can prove the correctness of a program with respect to a given specification and may be a valuable support in the difficult task of ensuring the quality of large software systems. However, the automated verification of concurrent software can be particularly challenging due to the vast complexity that non-deterministic scheduling causes. This thesis is concerned with techniques that reduce the complexity of concurrent programs in order to ease the verification task. We approach this problem from two orthogonal directions: state space reduction and reduction of non-determinism in executions of concurrent programs. Following the former direction, we present an algorithm for dynamic partial-order reduction, a state space reduction technique that avoids the verification of redundant executions. Our algorithm, EPOR, eagerly creates schedules for program fragments. In comparison to other dynamic partial-order reduction algorithms, it avoids redundant race and dependency checks. Our experiments show that EPOR runs considerably faster than a state-of-the-art algorithm, which allows in several cases to analyze programs with a higher number of threads within a given timeout. In the latter direction, we present a formal framework for using incomplete verification results to extract safe schedulers. As incomplete verification results do not need to proof the correctness of all possible executions of a program, their complexity can be significantly lower than complete verification results. Hence, they can be faster obtained. We constrain the scheduling of programs but not their inputs in order to preserve their full functionality. In our framework, executions under the scheduling constraints of an incomplete verification result are safe, deadlock-free, and fair. We instantiate our framework with the Impact model checking algorithm and find in our evaluation that it can be used to model check programs that are intractable for monolithic model checkers, synthesize synchronization via assume statements, and guarantee fair executions. In order to safely execute a program within the set of executions covered by an incomplete verification, scheduling needs to be constrained. We discuss how to extract and encode schedules from incomplete verification results, for both finite and infinite executions, and how to efficiently enforce scheduling constraints, both in terms of reducing the time to look up permission of executing the next event and executing independent events concurrently (by applying partial-order reduction). A drawback of enforcing scheduling constraints is a potential overhead in the execution time. However, in several cases, constrained executions turned out to be even faster than unconstrained executions. Our experimental results show that iteratively relaxing a schedule can significantly reduce this overhead. Hence, it is possible to adjust the incurred execution time overhead in order to find a sweet spot with respect to the amount of effort for creating schedules (i.e., the duration of verification). Interestingly, we found cases in which a much earlier reduction of execution time overhead is obtained by choosing favorable scheduling constraints, which suggests that execution time performance does not simply rely on the number of scheduling constraints but to a large extend also on their structure

Examining the Influence on Perceptions of Endometriosis via Analysis of Social Media Posts: Cross-sectional Study

Background: Social media platforms, such as Facebook and Instagram, are increasingly being used to share health-related information by "influencers," regular users, and institutions alike. While patients may benefit in various ways from these interactions, little is known about the types of endometriosis-related information published on social media. As digital opinion leaders influence the perceptions of their followers, physicians need to be aware about ideas and beliefs that are available online, in order to address possible misconceptions and provide optimal patient care. Objective: The aim of this study was to identify and analyze frequent endometriosis-related discussion topics on social media in order to offer caregivers insight into commonly discussed subject matter and aspects. Methods: We performed a systematic search using predefined parameters. Using the term "endometriosis" in Facebook's search function and a social media search engine, a list of Facebook pages was generated. A list of Instagram accounts was generated using the terms "endometriosis" and "endo" in Instagram's search function. Pages and accounts in English with 5000 or more followers or likes were included. Nonpublic, unrelated, or inactive pages and accounts were excluded. For each account, the most recent 10 posts were identified and categorized by two independent examiners using qualitative content analysis. User engagement was calculated using the numbers of interactions (ie, shares, likes, and comments) for each post, stratified by the number of followers. Results: A total of 39 Facebook pages and 43 Instagram accounts with approximately 1.4 million followers were identified. Hospitals and medical centers made up 15% (6/39) of the Facebook pages and 5% (2/43) of the Instagram accounts. Top accounts had up to 111,600 (Facebook) and 41,400 (Instagram) followers. A total of 820 posts were analyzed. On Facebook, most posts were categorized as "awareness" (101/390, 25.9% of posts), "education and research" (71/390, 18.2%), and "promotion" (64/390, 16.4%). On Instagram, the top categories were "inspiration and support" (120/430, 27.9% of posts), "awareness" (72/430, 16.7%), and "personal story" (72/430, 16.7%). The frequency of most categories differed significantly between platforms. User engagement was higher on Instagram than on Facebook (3.20% vs 0.97% of followers per post). On Instagram, the highest percentage of users engaged with posts categorized as "humor" (mean 4.19%, SD 4.53%), "personal story" (mean 3.02%, SD 4.95%), and "inspiration and support" (mean 2.83%, SD 3.08%). On Facebook, posts in the categories "awareness" (mean 2.05%, SD 15.56%), "humor" (mean 0.91%, SD 1.07%), and "inspiration and support" (mean 0.56%, SD 1.37%) induced the most user engagement. Posts made by hospitals and medical centers generated higher user engagement than posts by regular accounts on Facebook (mean 1.44%, SD 1.11% vs mean 0.88%, SD 2.71% of followers per post) and Instagram (mean 3.33%, SD 1.21% vs mean 3.19%, SD 2.52% of followers per post). Conclusions: Facebook and Instagram are widely used to share endometriosis-related information among a large number of users. Most posts offer inspiration or support, spread awareness about the disease, or cover personal issues. Followers mostly engage with posts with a humoristic, supportive, and awareness-generating nature. Health care providers should be aware about the topics discussed online, as this may lead to an increased understanding of the needs and demands of digitally proficient patients with endometriosis. Keywords: Facebook; Instagram; endometriosis; engagement; influencer; social medi

Popularity of endocrine endometriosis drugs and limited alternatives in the present and foreseeable future: A survey among 1420 affected women

Objectives: Endocrine drugs represent an important cornerstone of endometriosis therapy. Pharmaceutical alternatives with similar efficacy remain out of sight in the near future. Aim of this study is to investigate attitudes and perceptions concerning endocrine therapies among affected women. Study design: An online survey was distributed via social media in Austria, Germany, and Switzerland. Primary endpoints were satisfaction, attitudes and perceptions towards endocrine endometriosis drugs and secondary outcomes differences regarding demographic variables. Results: Of 1420 respondents, 63.5 % (n = 901) described their own attitude towards these drugs as rather negative. The most frequently reported unfavorable associations and experiences were sideeffects in general (85.5 %, n = 1181), change in libido (67.5 %, n = 932), hormone cycle disruptions (65.9 %, n = 910), and inefficiency at alleviating symptoms (38.2 %, n = 527). In total, 66.1 % (n = 935) were not satisfied with endocrine drugs for endometriosis. Age ≤ 30 years, living in a large city, and having an academic degree were significantly correlated to a more negative perception of these drugs and greater dissatisfaction with current endocrine endometriosis drugs. Conclusions: Among women with endometriosis - and particularly among those aged ≤30 years, being large-city residents, or holding an academic degree - there appears to be a relevant degree of rejection and wariness towards endocrine endometriosis drugs. Given the prevalence of endometriosis and the few pharmaceutical alternatives on the horizon, these data point a growing need for further research and development of non-hormonal drugs for the treatment of endometriosis. Keywords: Endometriosis; Endometriosis drug therapy; Endometriosis social media; Endometriosis survey

Effects of vitamin D supplementation in endometriosis: a systematic review

Background: There is a growing body of human, animal and in vitro studies on vitamin D (vit D) substitution in endometriosis. The aim of this systematic review is to critically appraise and qualitatively synthesize the results of the available studies that examine the supplementation of vit D for endometriosis treatment. Methods: A systematic search of the literature was conducted in four electronic databases (Medline, Cochrane, Scopus, Embase) and grey literature for original research articles on humans, animals and in vitro models published in any language. Results: Four human studies, four animal studies and four in vitro studies were included. Quantitative synthesis of human studies showed no significant effect of vit D intake for dysmenorrhea (2 studies, 44 vit D vs 44 placebo, mean -0.71, 95% CI -1.94, 0.51) and non-cyclic pelvic pain (2 studies, 42 vit D vs 38 placebo, mean 0.34, 95% CI -0.02, 0.71). Regarding reproductive outcomes in women with endometriosis after in vitro fertilization, the only available study showed no differences between women taking vit D and women taking placebo. Three of the four included animal studies showed regression of endometriotic implants when treated with vit D. The in vitro studies demonstrated that vit D decreases invasion and proliferation of endometriotic lesions without affecting apoptosis. Conclusions: Although in vitro and animal studies suggest regression of the endometriotic implants and decrease of invasion and proliferation after vit D supplementation, this was not reflected in the results of the meta-analysis, which showed no benefit of vit D supplementation in patients with endometriosis and dysmenorrhea or non-cyclic pelvic pain as well as on the outcome of IVF treatment. However, given the heterogeneity and the diversity of the available studies, more research is required to shed light on the role of vit D supplementation in women with endometriosis. Keywords: 1,25(OH)2D; 25(OH)D; 25(ΟΗ)D3; Endometriosis; Supplementation; Vitamin

Steering self-organisation through confinement

Self-organisation is the spontaneous emergence of spatio-temporal structures and patterns from the interaction of smaller individual units. Examples are found across many scales in very different systems and scientific disciplines, from physics, materials science and robotics to biology, geophysics and astronomy. Recent research has highlighted how self-organisation can be both mediated and controlled by confinement. Confinement occurs through interactions with boundaries, and can function as either a catalyst or inhibitor of self-organisation. It can then become a means to actively steer the emergence or suppression of collective phenomena in space and time. Here, to provide a common framework for future research, we examine the role of confinement in self-organisation and identify overarching scientific challenges across disciplines that need to be addressed to harness its full scientific and technological potential. This framework will not only accelerate the generation of a common deeper understanding of self-organisation but also trigger the development of innovative strategies to steer it through confinement, with impact, e.g., on the design of smarter materials, tissue engineering for biomedicine and crowd management

Search for a Technicolor omega_T Particle in Events with a Photon and a b-quark Jet at CDF

If the Technicolor omega_T particle exists, a likely decay mode is omega_T -> gamma pi_T, followed by pi_T -> bb-bar, yielding the signature gamma bb-bar. We have searched 85 pb^-1 of data collected by the CDF experiment at the Fermilab Tevatron for events with a photon and two jets, where one of the jets must contain a secondary vertex implying the presence of a b quark. We find no excess of events above standard model expectations. We express the result of an exclusion region in the M_omega_T - M_pi_T mass plane.Comment: 14 pages, 2 figures. Available from the CDF server (PS with figs): http://www-cdf.fnal.gov/physics/pub98/cdf4674_omega_t_prl_4.ps FERMILAB-PUB-98/321-

Observation of Hadronic W Decays in t-tbar Events with the Collider Detector at Fermilab

We observe hadronic W decays in t-tbar -> W (-> l nu) + >= 4 jet events using a 109 pb-1 data sample of p-pbar collisions at sqrt{s} = 1.8 TeV collected with the Collider Detector at Fermilab (CDF). A peak in the dijet invariant mass distribution is obtained that is consistent with W decay and inconsistent with the background prediction by 3.3 standard deviations. From this peak we measure the W mass to be 77.2 +- 4.6 (stat+syst) GeV/c^2. This result demonstrates the presence of two W bosons in t-tbar candidates in the W (-> l nu) + >= 4 jet channel.Comment: 20 pages, 4 figures, submitted to PR

Search for Chargino-Neutralino Associated Production at the Fermilab Tevatron Collider

We have searched in $p \bar{p}$ collisions at $\sqrt{s}$ = 1.8 TeV for events with three charged leptons and missing transverse energy. In the Minimal Supersymmetric Standard Model, we expect trilepton events from chargino-neutralino (\chione \chitwo) pair production, with subsequent decay into leptons. We observe no candidate $e^+e^-e^\pm$, $e^+e^-\mu^\pm$, $e^\pm\mu^+\mu^-$ or $\mu^+\mu^-\mu^\pm$ events in 106 pb$^{-1}$ integrated luminosity. We present limits on the sum of the branching ratios times cross section for the four channels: \sigma_{\chione\chitwo}\cdot BR(\chione\chitwo\to 3\ell+X) 81.5 \mgev\sp and M_\chitwo > 82.2 \mgev\sp for $\tan\beta=2$, $\mu =-600$~\mgev\sp and M_\squark= M_\gluino.Comment: 9 pages and 3 figure