Reachability Analysis of Innermost Rewriting

We consider the problem of inferring a grammar describing the output of a functional program given a grammar describing its input. Solutions to this problem are helpful for detecting bugs or proving safety properties of functional programs and, several rewriting tools exist for solving this problem. However, known grammar inference techniques are not able to take evaluation strategies of the program into account. This yields very imprecise results when the evaluation strategy matters. In this work, we adapt the Tree Automata Completion algorithm to approximate accurately the set of terms reachable by rewriting under the innermost strategy. We prove that the proposed technique is sound and precise w.r.t. innermost rewriting. The proposed algorithm has been implemented in the Timbuk reachability tool. Experiments show that it noticeably improves the accuracy of static analysis for functional programs using the call-by-value evaluation strategy

Teacher governance reforms and social cohesion in South Africa: from intention to reality

The governance of teachers during apartheid in South Africa was characterised by high levels of disparity in teacher distribution and in conditions of labour. In the postapartheid context policies and interventions that govern teachers are critical, and teachers can be seen to be placed in a central role as actors whose distribution, employment, recruitment and deployment can serve to redress the past, promote equity and build trust for social cohesion. In this context, this paper examines several teacher governance mechanisms and interventions, namely the post provisioning norm and standards (PPNs), the Funza Lushaka Bursary Programme (FLBP), and the South African Council of Educators. The analysis suggests that undifferentiated policy frameworks for teacher governance result in measures that weakly account for differing contextual realities and persistent inequality. Additionally, the emphasis on technocratic measures of accountability in teacher governance interventions constrains teachers' agency to promote peace and social cohesion

Social cohesion and initial teacher education in South Africa

Initial teacher education (ITE) is a key focus in current policy particularly in respect to shaping student teachers' dispositions and capabilities to effect change within the systems they will work, and for the learners they will teach. Teachers' pedagogic strategies also mediate inequalities and continuities within the education system, linked to the schooling system and society they operate within. In South Africa, contextually relevant pedagogical strategies that address diversity, reconciliation, and promote social cohesion are crucial to enable initial teacher education to prepare teachers in this way (Sosibo, 2013). This paper draws on data from a case study of an ITE programme at one higher education institution (HEI) in South Africa. The data was collected through semi-structured interviews with students and lecturers, focus groups, documentary analysis, and a survey of initial teacher educators, and was part of a large-scale study that focused on teachers as agents of social cohesion in South Africa (Sayed et al., 2015). Specifically, it considers how student teachers are prepared to enact social cohesion in the classroom. The paper concludes by discussing several implications of the research for ITE in South Africa

Reachability Analysis of Innermost Rewriting

Approximating the set of terms reachable by rewriting finds more and more applications ranging from termination proofs of term rewriting systems, cryp- tographic protocol verification to static analysis of programs. However, since approximation techniques do not take rewriting strategies into account, they build very coarse approximations when rewriting is constrained by a specific strategy. In this work, we propose to adapt the Tree Automata Completion algorithm to accurately approximate the set of terms reachable by rewriting under the inner- most strategy. We prove that the proposed technique is sound and precise w.r.t. innermost rewriting. The proposed algorithm has been implemented in the Timbuk reachability tool. Experiments shows that it noticeably improves the accuracy of static analysis for functional programs using the call-by-value evaluation strategy. In particular, for some functional programs needing lazy evaluation to terminate, the computed approximations are precise enough to prove the absence of innermost normal forms, i.e. prove non termination of the program with call-by-value

Scavenging by a Bobcat, Lynx rufus

There are few available reports of scavenging (carrion foraging) by Bobcats (Lynx rufus). We recovered the remains of a Gray Squirrel (Sciurus carolinensis) from the stomach of a road-killed female Bobcat in Dutchess County, New York. The presence of Blow Fly eggs on the squirrel remains indicate that it was consumed as carrion. To our knowledge this is the third confirmed instance of scavenging by a Bobcat

Heat-stable metagenomic carbonic andydrases and their use

The present invention relates to polypeptides having carbonic anhydrase activity and polynucleotides encoding the polypeptides. The invention also relates to nucleic acid constructs, vectors, and host cells comprising the polynucleotides as well as methods of producing and using the polypeptides

Hydra: A Parallel Adaptive Grid Code

We describe the first parallel implementation of an adaptive particle-particle, particle-mesh code with smoothed particle hydrodynamics. Parallelisation of the serial code, ``Hydra'', is achieved by using CRAFT, a Cray proprietary language which allows rapid implementation of a serial code on a parallel machine by allowing global addressing of distributed memory. The collisionless variant of the code has already completed several 16.8 million particle cosmological simulations on a 128 processor Cray T3D whilst the full hydrodynamic code has completed several 4.2 million particle combined gas and dark matter runs. The efficiency of the code now allows parameter-space explorations to be performed routinely using $64^3$ particles of each species. A complete run including gas cooling, from high redshift to the present epoch requires approximately 10 hours on 64 processors. In this paper we present implementation details and results of the performance and scalability of the CRAFT version of Hydra under varying degrees of particle clustering.Comment: 23 pages, LaTex plus encapsulated figure

Interactive effects of vascular risk burden and advanced age on cerebral blood flow.

Vascular risk factors and cerebral blood flow (CBF) reduction have been linked to increased risk of cognitive impairment and Alzheimer's disease (AD); however the possible moderating effects of age and vascular risk burden on CBF in late life remain understudied. We examined the relationships among elevated vascular risk burden, age, CBF, and cognition. Seventy-one non-demented older adults completed an arterial spin labeling MR scan, neuropsychological assessment, and medical history interview. Relationships among vascular risk burden, age, and CBF were examined in a priori regions of interest (ROIs) previously implicated in aging and AD. Interaction effects indicated that, among older adults with elevated vascular risk burden (i.e., multiple vascular risk factors), advancing age was significantly associated with reduced cortical CBF whereas there was no such relationship for those with low vascular risk burden (i.e., no or one vascular risk factor). This pattern was observed in cortical ROIs including medial temporal (hippocampus, parahippocampal gyrus, uncus), inferior parietal (supramarginal gyrus, inferior parietal lobule, angular gyrus), and frontal (anterior cingulate, middle frontal gyrus, medial frontal gyrus) cortices. Furthermore, among those with elevated vascular risk, reduced CBF was associated with poorer cognitive performance. Such findings suggest that older adults with elevated vascular risk burden may be particularly vulnerable to cognitive change as a function of CBF reductions. Findings support the use of CBF as a potential biomarker in preclinical AD and suggest that vascular risk burden and regionally-specific CBF changes may contribute to differential age-related cognitive declines