Interpolant-Based Transition Relation Approximation

In predicate abstraction, exact image computation is problematic, requiring in the worst case an exponential number of calls to a decision procedure. For this reason, software model checkers typically use a weak approximation of the image. This can result in a failure to prove a property, even given an adequate set of predicates. We present an interpolant-based method for strengthening the abstract transition relation in case of such failures. This approach guarantees convergence given an adequate set of predicates, without requiring an exact image computation. We show empirically that the method converges more rapidly than an earlier method based on counterexample analysis.Comment: Conference Version at CAV 2005. 17 Pages, 9 Figure

What is driving the 'African Growth Miracle'?

We show that much of Africa s recent growth and poverty reduction can be traced to a substantive decline in the share of the labor force engaged in agriculture. This decline has been accompanied by a systematic increase in the productivity of the labor force, as it has moved from low productivity agriculture to higher productivity manufacturing and services. These declines have been more rapid in countries where the initial share of the labor force engaged in agriculture is the highest and where commodity price increases have been accompanied by improvements in the quality of governance

Sub-maximal blood lactate assessment of professional youth soccer players throughout the soccer season

Aerobic fitness is recognised as a very important fitness component in soccer (Reilly, 1994, Science and Soccer. E&FN Spon, UK). Thus, it is of importance to monitor the aerobic fitness of professional soccer players periodically throughout the soccer season. The aim of this study was to examine the changes in aerobic fitness of professional youth soccer players from the pre-season period to the start of the competitive season and throughout the competitive season. Thirty-seven male professional youth soccer players aged (mean +/- sd) 18.9 +/- 1.8 years participated in this study. The players were tested at six time-points throughout the playing season - sub-maximal running was performed on a treadmill (Woodway Ergo ES2, Cranlea, UK) and consisted of at least six progressive four-minute stages. Fingertip blood samples were collected at the end of each running speed and analysed for whole blood lactate concentration using an Analox GM7 analyser (Analox Instruments, UK). Although 37 soccer players participated in this study, not all players were tested at each time point (Table A), in order to account for the within-subjects design and the fact that there are missing data at certain testing time-points (which is assumed to be missing at random), a Repeated Measures Analysis of Variance with Bonferroni Multiple comparisons, and Bonferroni adjusted paired t-tests were used to determine any significant changes in aerobic fitness, using running speeds at the lactate threshold [vLT] and 4 mmol.l-1 [vLac4]. Aerobic fitness increased from the start of pre-season training to October (5 weeks into the competitive season) as evidenced by an increase in mean vLT and mean vLac4 (p<0.001) (Table 1). The mean vLT was highest in December (p<0.001) compared with January and June. Other fluctuations in the mean vLT throughout the competitive playing season were found to be non-significant. No significant differences in mean vLac4 were found during the competitive season. In conclusion, aerobic fitness increased from the start of pre-season training to the early weeks of the competitive playing season. The mean vLT was found to be highest in December. These findings demonstrate that the pre-season training was effective in improving aerobic fitness. The feet that the January, April and June vLT scores were lower than those in December suggests that coaches should examine the aerobic training regimens in the second half of the season. Table A. Lactate threshold (vLT) and 4 mmol.l (vLac4) running velocity (mean +/- sd) and number of observations for each testing time-point a - significantly higher than pre-season (p<0.001) b - significantly higher than January and June vLT (p<0.001)

NeuroComb: Improving SAT Solving with Graph Neural Networks

Propositional satisfiability (SAT) is an NP-complete problem that impacts many research fields, such as planning, verification, and security. Mainstream modern SAT solvers are based on the Conflict-Driven Clause Learning (CDCL) algorithm. Recent work aimed to enhance CDCL SAT solvers by improving their variable branching heuristics through predictions generated by Graph Neural Networks(GNNs). However, so far this approach either has not made solving more effective, or has required online access to substantial GPU resources. Aiming to make GNN improvements practical, this paper proposes an approach called NeuroComb, which builds on two insights: (1) predictions of important variables and clauses can be combined with dynamic branching into a more effective hybrid branching strategy, and (2) it is sufficient to query the neural model only once for the predictions before the SAT solving starts. NeuroComb is implemented as an enhancement to a classic CDCL solver called MiniSat and a more recent CDCL solver called Glucose. As a result, it allowed MiniSat to solve 11% and Glucose 5% more problems on the recent SATCOMP-2021 competition problem set, with the computational resource requirement of only one GPU. NeuroComb is therefore a both effective and practical approach to improving SAT solving through machine learning

A Case Study in Analytic Protocol Analysis in ACL2

When verifying computer systems we sometimes want to study their asymptotic behaviors, i.e., how they behave in the long run. In such cases, we need real analysis, the area of mathematics that deals with limits and the foundations of calculus. In a prior work, we used real analysis in ACL2s to study the asymptotic behavior of the RTO computation, commonly used in congestion control algorithms across the Internet. One key component in our RTO computation analysis was proving in ACL2s that for all alpha in [0, 1), the limit as n approaches infinity of alpha raised to n is zero. Whereas the most obvious proof strategy involves the logarithm, whose codomain includes irrationals, by default ACL2 only supports rationals, which forced us to take a non-standard approach. In this paper, we explore different approaches to proving the above result in ACL2(r) and ACL2s, from the perspective of a relatively new user to each. We also contextualize the theorem by showing how it allowed us to prove important asymptotic properties of the RTO computation. Finally, we discuss tradeoffs between the various proof strategies and directions for future research.Comment: In Proceedings ACL2-2023, arXiv:2311.0837

Utilization of an Anti-gravity Treadmill in a Physical Activity Program with Female Breast Cancer Survivors: a Pilot Study

International Journal of Exercise Science 9(1): 101- 109, 2016. Breast Cancer survivors can experience a myriad of physical and psychological benefits as a result of regular exercise. This study aimed to build on previous research using lower impact exercise programs by using an anti-gravity (Alter-G®) treadmill to administer cardiovascular training. The purpose of this study was to determine the effectiveness a physical activity program, including an Alter-G® treadmill, for improving physiological and psychosocial measures in female breast cancer survivors. A 14-week intervention using an AB-AB study design was employed. Six female breast cancer survivors were recruited to participate in the study. Participants attended three 60-minute sessions per week, consisting of a combination of muscular strength/endurance, and cardiovascular endurance exercises. Consistent with current literature and guidelines, exercise interventions were individualized and tailored to suit individuals. Data was collected and analyzed in 2013. Visual inspection of results found improvements in cardiovascular endurance and measures of body composition. Quality of life was maintained and in some cases, improved. Finally, no adverse effects were reported from the participants, and adherence to the program for those who completed the study was 97%. The results of this study suggest that the use of a physical activity program in combination with an Alter-G® treadmill may provide practical and meaningful improvements in measures of cardiovascular endurance and body composition

Informationの多変数解析への応用について

The Paleocene–Eocene Thermal Maximum (PETM), at ca. 55.8 Ma, is one of the most studied instances of past greenhouse gas-induced global warming. As such, it provides a rich opportunity to examine the impact of such global change on local climates. The effects of increased continental and sea surface temperatures on local precipitation and humidity during the PETM remain poorly constrained and studies reveal complex, regional differences; whilst some localities appear to experience a net increase in humidity, others exhibit the opposite. Crucially, there are few records of hydrological change from tropical regions. Recent onshore drilling expeditions in Tanzania have yielded expanded sedimentary sections, deposited in a marine environment, that span much of the Late Cretaceous and Paleogene and show exceptionally good preservation of both calcareous microfossils and organic matter. The PETM interval has previously been constrained by both biostratigraphy and carbon isotopic records and spans ca. 7 m of section. Lipid distributions, including various terrestrial, marine and bacterial biomarkers and their hydrogen isotopic compositions, as well as mineralogy, were used to examine East African vegetation and hydrological responses to the global change occurring at the PETM. Although total organic carbon contents decrease, the concentrations of both higher plant (n-alkanes, n-alkanoic acids) and soil bacterial (glycerol dialkyl glycerol tetraethers) biomarkers increase dramatically at the onset of the PETM negative carbon isotope excursion (CIE), suggesting an increased discharge of fluvial sedimentary organic matter. Similarly, mineralogical indicators of terrestrial input – including Ti/Al and Si/Al ratios, quartz contents and, notably, the proportion of kaolinite – also increase at the onset of the CIE. However, higher plant leaf wax n-alkanes (C27, C29 and C31) become more deuterium-enriched throughout the same interval, suggesting a more arid and/or hotter, rather than a more humid, environment. This evidence collectively suggests an East African early PETM climate characterised by overall hot and arid conditions punctuated by intense, perhaps seasonal, precipitation events. These data match observations from other locations at mid-latitudes, suggesting that the humid climate often suggested for the PETM was not globally widespread

Simulating Photodynamic Therapy for the Treatment of Glioblastoma using Monte Carlo Radiative Transport

Significance: Glioblastoma (GBM) is a rare but deadly form of brain tumor with a low median survival rate of 14.6 months, due to its resistance to treatment. An independent simulation of the INtraoperative photoDYnamic therapy for GliOblastoma (INDYGO) trial, a clinical trial aiming to treat the GBM resection cavity with photodynamic therapy (PDT) via a laser coupled balloon device, is demonstrated. Aim: To develop a framework providing increased understanding for the PDT treatment, its parameters, and their impact on the clinical outcome. Approach: We use Monte Carlo radiative transport techniques within a computational brain model containing a GBM to simulate light path and PDT effects. Treatment parameters (laser power, photosensitizer concentration, and irradiation time) are considered, as well as PDT’s impact on brain tissue temperature. Results: The simulation suggests that 39% of post-resection GBM cells are killed at the end of treatment when using the standard INDYGO trial protocol (light fluence = 200 J∕cm 2 at balloon wall) and assuming an initial photosensitizer concentration of 5 μM. Increases in treatment time and light power (light fluence = 400 J∕cm 2 at balloon wall) result in further cell kill but increase brain cell temperature, which potentially affects treatment safety. Increasing the p hotosensitizer concentration produces the most significant increase in cell kill, with 61% of GBM cells killed when doubling concentration to 10 μM and keeping the treatment time and power the same. According to these simulations, the standard trial protocol is reasonably well optimized with improvements in cell kill difficult to achieve without potentially dangerous increases in temperature. To improve treatment outcome, focus should be placed on improving the photosensitizer. Conclusions: With further development and optimization, the simulation could have potential clinical benefit and be used to help plan and optimize intraoperative PDT treatment for GBM.</p