Abstraction-guided synthesis of synchronization

We present a novel framework for automatic inference of efficient synchronization in concurrent programs, a task known to be difficult and error-prone when done manually. Our framework is based on abstract interpretation and can infer synchronization for infinite state programs. Given a program, a specification, and an abstraction, we infer synchronization that avoids all (abstract) interleavings that may violate the specification, but permits as many valid interleavings as possible. Combined with abstraction refinement, our framework can be viewed as a new approach for verification where both the program and the abstraction can be modified on-the-fly during the verification process. The ability to modify the program, and not only the abstraction, allows us to remove program interleavings not only when they are known to be invalid, but also when they cannot be verified using the given abstraction. We implemented a prototype of our approach using numerical abstractions and applied it to verify several example programs.     

Carbodiimide cross-linking counteracts the detrimental effects of gamma irradiation on the physical properties of collagen-hyaluronan sponges

Collagen-based scaffolds are extensively used in biomaterials and tissue engineering applications. These scaffolds have shown great biocompatibility and versatility, but their relatively low mechanical properties may limit use in orthopaedic load-bearing applications. Moreover, terminal sterilization with gamma irradiation, as is commonly performed with commercial devices, presents concerns over structural integrity and enzymatic stability. Therefore, the goal of this study was to test the hypothesis that EDC/NHS cross-linking (10?mM/5?mM) can protect collagen-hyaluronan sponges from the damaging effects of gamma irradiation. Specifically, we evaluated compressive and tensile mechanical properties, enzymatic stability, porosity and pore size, and swelling ratio. Ultimate tensile strength and elastic modulus exhibited increases (168.5 and 245.8%, respectively) following irradiation, and exhibited over tenfold increases (1049.2 and 1270.6%, respectively) following cross-linking. Irradiation affected pore size (38.4% decrease), but cross-linking prior to irradiation resulted in only a 17.8% decrease. Cross-linking also showed an offsetting effect on the equilibrium modulus, enzymatic stability, and swelling ratio of sponges. These results suggest that carbodiimide cross-linking of collagen-hyaluronan sponges can mitigate the structural damage typically experienced during gamma irradiation, warranting their use in tissue engineering applications.

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Photodegradation of three stormwater biocides

Photodegradation of carbendazim, diuron and terbutryn was investigated at controlled laboratory conditions under UV light and under natural sunlight. Demineralized water and two different waters from stormwater retention ponds were used. An observed decline in biocide concentration was related to the accumulated light energy during the degradation time. Diuron and terbutryn were degradable under UV light following 1^st order degradation kinetics, while no significant decrease of carbendazim was observed throughout the duration of experiments. Photodegradation of diuron and terbutryn was slightly faster in demineralized water compared with pond water. The outdoors experiments showed limited degradation of the compounds for the duration of the test (8–17 days). The results emphasize the importance of water type, the wavelength and energy of the light when investigating pollutant’s photo fate. Also, this study indicates that photodegradation is not a major process contributing to the removal of carbendazim, diuron and terbutryn in stormwater retention ponds.     

Gamebirds: A sustainable food source in Southern Africa?

In order to alleviate the current food security situation the world is faced with, it is essential to investigate meat sources which have the potential to be used in a sustainable manner. This review provides substantial arguments to prove the viability of sport hunted wildfowl as a food source in Southern Africa. However, before the use of wildfowl meat can be realised, there are certain challenges to overcome in order to ensure meat of the best possible quality reaches the consumer. Important aspects to consider regarding the eating quality of wildfowl meat are identified and include the physical activity of the different portions and muscle fibre types, diet, breeding, age and gender as well as the post mortem handling/ageing of the meat. The safety issues involved in producing gamebird meat i.e. shot contamination (microbial or lead), are also discussed. Other areas that warrant scientific research include investigating the intrinsic and extrinsic factors that may have an influence on the ultimate meat quality and exploring possible techniques of improving the eating quality of wildfowl meat. The insights these investigations will provide have the potential to increase the commercial viability, directly or indirectly, of African wildfowl meat and thus contribute to food security.     

Accelerating math development in Head Start classrooms.

Teachers implemented a 6-week classroom intervention designed to promote emergent math skills and math interest in preschool-aged children. Teachers in experimental classrooms incorporated math-relevant activities into their daily routine during circle time, transitions, mealtime, and small-group activities. Control classrooms engaged in their typical activities. After the program, experimental children scored significantly higher than control children on a standardized test of math ability and enjoyed math activities more than the control children, as measured by both teacher and self-report. Teachers rated the program as highly satisfactory and reported that they increased their own enjoyment and skill in implementing math activities in their classrooms. The intervention effects were largely accounted for by substantial gains by boys, whereas girls showed much smaller program response. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Measuring impact by a full option method and the notion of bibliometric spectra

A full option method for determining impact takes into account citations to all cited publications, instead of limiting the analysis to ISI-publications only, as usually done in the standard method. The method was tested for the 258 early Ghent professors, teaching in 6 different faculties. The impact of monographs is, in general, much larger than the impact of articles (whether of ISI-type or not). This result remains valid for all six faculties separately. Limiting the bibliometric visibility to ISI-publications reduces the number of citations to only 16%. Bibliometric spectra are presented, in which citations, cited publications and their impact are shown in function of the year of publication. The number of cited publications is always important to expose the influence of activity (production) upon bibliometric scores. For the faculty of Arts, the citations to early professors are compared with those obtained for the presentday generation: the bibliometric spectrum for the former group is rather discontinuous (showing a large erosion in the number of citations by year), whereas that of the latter is continuous. The Ghent citation data are also compared with those given internationally in the same period.     

Prenatal exposure to environmental toxin: A test of the multiple effects model.

The multiple effects model of teratological exposure predicts that neonatal deficits associated with intrauterine exposure to small doses of a potentially teratogenic agent will vary considerably across individuals. This hypothesis was tested in a sample of 242 newborns exposed prenatally to low levels of polychlorinated biphenyls (PCBs) from maternal consumption of contaminated lake fish and 71 control infants whose mothers did not eat these fish. Behavioral outcomes were assessed using the Brazelton Neonatal Behavioral Assessment Scale (NABS). Contaminated fish consumption predicted motoric immaturity, poorer lability of states, a greater amount of startle, and more abnormally weak (hypoactive) reflexes. The most highly exposed Ss were more likely than controls to be classified as "worrisome" on 3 NBAS clusters. Results from a stepwise regression analysis are consistent with the multiple effects model, indicating that some affected Ss were born small and/or early, whereas others exhibited one or another of the behavioral deficits. The analysis indicated that 12.2% of the variance in contaminated fish consumption was associated with measurable neonatal deficits. (40 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A logic of reachable patterns in linked data-structures

We define a new decidable logic for expressing and checking invariants of programs that manipulate dynamically-allocated objects via pointers and destructive pointer updates. The main feature of this logic is the ability to limit the neighborhood of a node that is reachable via a regular expression from a designated node. The logic is closed under boolean operations (entailment, negation) and has a finite model property. The key technical result is the proof of decidability.We show how to express preconditions, postconditions, and loop invariants for some interesting programs. It is also possible to express properties such as disjointness of data-structures, and low-level heap mutations. Moreover, our logic can express properties of arbitrary data-structures and of an arbitrary number of pointer fields. The latter provides a way to naturally specify postconditions that relate the fields on the entry of a procedure to the field on the exit of a procedure. Therefore, it is possible to use the logic to automatically prove partial correctness of programs performing low-level heap mutations.