Parallel Recursive State Compression for Free

This paper focuses on reducing memory usage in enumerative model checking, while maintaining the multi-core scalability obtained in earlier work. We present a tree-based multi-core compression method, which works by leveraging sharing among sub-vectors of state vectors. An algorithmic analysis of both worst-case and optimal compression ratios shows the potential to compress even large states to a small constant on average (8 bytes). Our experiments demonstrate that this holds up in practice: the median compression ratio of 279 measured experiments is within 17% of the optimum for tree compression, and five times better than the median compression ratio of SPIN's COLLAPSE compression. Our algorithms are implemented in the LTSmin tool, and our experiments show that for model checking, multi-core tree compression pays its own way: it comes virtually without overhead compared to the fastest hash table-based methods.Comment: 19 page

Statistical Symbolic Execution with Informed Sampling

Symbolic execution techniques have been proposed recently for the probabilistic analysis of programs. These techniques seek to quantify the likelihood of reaching program events of interest, e.g., assert violations. They have many promising applications but have scalability issues due to high computational demand. To address this challenge, we propose a statistical symbolic execution technique that performs Monte Carlo sampling of the symbolic program paths and uses the obtained information for Bayesian estimation and hypothesis testing with respect to the probability of reaching the target events. To speed up the convergence of the statistical analysis, we propose Informed Sampling, an iterative symbolic execution that first explores the paths that have high statistical significance, prunes them from the state space and guides the execution towards less likely paths. The technique combines Bayesian estimation with a partial exact analysis for the pruned paths leading to provably improved convergence of the statistical analysis. We have implemented statistical symbolic execution with in- formed sampling in the Symbolic PathFinder tool. We show experimentally that the informed sampling obtains more precise results and converges faster than a purely statistical analysis and may also be more efficient than an exact symbolic analysis. When the latter does not terminate symbolic execution with informed sampling can give meaningful results under the same time and memory limits

Attendee satisfaction in festival activity: Innibos National Arts Festival

Despite the growth in festival tourism in South Africa and the paucity and infrequent nature of festival research, very little research exists on addressing what classifies a festival as successful. Well organized, promoted and managed events have been linked to attendee satisfaction, resulting in a successful event. Similarly, there is a positive connection between customer satisfaction, loyalty and retention which underlines the importance for festivals to be successful and sustainable. This study employs an on-site survey of 500 visitors attending the Innibos National Arts Festival in Mbombela, South Africa. Eight constructs were investigated based on the SERVQUAL and Grönroos model to determine the overall satisfaction of the attendees. The statistical analysis was performed using the marginal distributions of variable and construct analysis based on the post data. This study aimed at determining the overall satisfaction levels of the between attendee’s at the festival

Emerging strategies of targeting lipoprotein lipase for metabolic and cardiovascular diseases

Although statins and other pharmacological approaches have improved the management of lipid abnormalities, there exists a need for newer treatment modalities especially for the management of hypertriglyceridemia. Lipoprotein lipase (LPL), by promoting hydrolytic cleavage of the triglyceride core of lipoproteins, is a crucial node in the management of plasma lipid levels. Although LPL expression and activity modulation is observed as a pleiotropic action of some the commonly used lipid lowering drugs, the deliberate development of drugs targeting LPL has not occurred yet. In this review, we present the biology of LPL, highlight the LPL modulation property of currently used drugs and review the novel emerging approaches to target LPL

Adventure tourists in Pretoria, South Africa: A demographic profile

Adventure activities and experiences constantly evolve because individuals, motives, behaviours, and experiences differ and change over time. In order to assist adventure tourism companies to promote and sell specific activities and experiences that will meet the specific needs and wants of their identified target markets, this paper focuses on the demographic profile of adventure tourists who used the products/services of adventure tourism companies within Pretoria, South Africa. The realised sample was 234, providing a 93.6% response rate. The research instrument used was a self-completing questionnaire. Based on the results, these adventure tourists were Afrikaans speaking individuals between the ages of twenty-eight and forty-nine years. Their households consisted of two to four people and there were generally two income earners per household. This study established that there is a need for further researching of comprehensive adventure tourist profiles

The role of tourist guides in interpretation: a survey of secondary school teachers at Maropeng and the Sterkfontein caves, South Africa.

Interpretation, either explicitly or implicitly, aims to stimulate, facilitate and extend people’s understanding of the place or attraction so that empathy towards heritage, conservation, culture and landscape can be developed. However, in tourism research, interpretation in tour guiding has previously not received the attention it deserves. The main aim of this paper is to explore the role of tourist guides in interpretation as perceived by secondary school teachers. In general, respondents perceived tourist guides’ interpretation to be important, and they were satisfied with the way in which guides applied the principles of interpretation throughout their tours. Understanding visitor satisfaction presents information related to how well the attributes of the tourist attraction match the visitors’ preferences, which may help tourist attraction marketers in improving the quality of their products and services in order to meet visitors’ preferences. In addition, marketers should attract a number of visitors that can be managed in order to protect the natural and cultural resources of the attraction. The results of this study will hopefully inform Maropeng á Afrika marketers about secondary school teachers’ satisfaction on tourist guides’ interpretation and how important interpretation is to the respondents. In addition, the results will help the attractions to improve guided school tours and enhance offerings to Maropeng and the Sterkfontein caves in South Africa

Evolving Identification of Blood Cells Associated with Clinically Isolated Syndrome: Importance of Time since Clinical Presentation and Diagnostic MRI

It is not clear how the profile of immune cells in peripheral blood differs between patients with clinically isolated syndrome (CIS) and healthy controls (HC). This study aimed to identify a CIS peripheral blood signature that may provide clues for potential immunomodulatory approaches early in disease. Peripheral blood mononuclear cells (PBMCs) were collected from 18 people with CIS, 19 HC and 13 individuals with other demyelinating conditions (ODC) including multiple sclerosis (MS). Individuals with CIS separated into two groups, namely those with early (≤14 days post-diagnostic magnetic resonance imaging (MRI); n = 6) and late (≥27 days; n = 12) blood sampling. Transitional B cells were increased in the blood of CIS patients independently of when blood was taken. However, there were two time-dependent effects found in the late CIS group relative to HC, including decreased CD56bright NK cells, which correlated significantly with time since MRI, and increased CD141+ myeloid dendritic cell (mDC2) frequencies. Higher CD1c+ B cells and lower non-classical monocyte frequencies were characteristic of more recent demyelinating disease activity (ODC and early CIS). Analysing cell populations by time since symptoms (subjective) and diagnostic MRI (objective) may contribute to understanding CIS

Structure-activity and in vivo evaluation of a novel lipoprotein lipase (LPL) activator

Elevated triglycerides (TG) contribute towards increased risk for cardiovascular disease. Lipoprotein lipase (LPL) is an enzyme that is responsible for the metabolism of core triglycerides of very-low density lipoproteins (VLDL) and chylomicrons in the vasculature. In this study, we explored the structure-activity relationships of our lead compound (C10d) that we have previously identified as an LPL agonist. We found that the cyclopropyl moiety of C10d is not absolutely necessary for LPL activity. Several substitutions were found to result in loss of LPL activity. The compound C10d was also tested in vivo for its lipid lowering activity. Mice were fed a high-fat diet (HFD) for four months, and treated for one week at 10 mg/kg. At this dose, C10d exhibited in vivo biological activity as indicated by lower TG and cholesterol levels as well as reduced body fat content as determined by ECHO-MRI. Furthermore, C10d also reduced the HFD induced fat accumulation in the liver. Our study has provided insights into the structural and functional characteristics of this novel LPL activator