An alternate proof of Wise's Malnormal Special Quotient Theorem

We give an alternate proof of Wise's Malnormal Special Quotient Theorem (MSQT), avoiding cubical small cancellation theory. We also show how to deduce Wise's Quasiconvex Hierarchy Theorem from the MSQT and theorems of Hsu--Wise and Haglund--Wise.Comment: 42 pages, 10 figures. Version 2 contains minor changes, addressing referee comments. To appear in Forum of Mathematics, P

Online and offline heuristics for inferring hierarchies of repetitions in sequences

Hierarchical dictionary-based compression schemes form a grammar for a text by replacing each repeated string with a production rule. While such schemes usually operate online, making a replacement as soon as repetition is detected, offline operation permits greater freedom in choosing the order of replacement. In this paper, we compare the online method with three offline heuristics for selecting the next substring to replace: longest string first, most common string first, and the string that minimized the size of the grammar locally. Surprisingly, two of the offline techniques, like the online method, run in time linear in the size of the input. We evaluate each technique on artificial and natural sequences. In general, the locally-most-compressive heuristic performs best, followed by most frequent, the online technique, and, lagging by some distance, the longest-first technique

Detecting sequential structure

Programming by demonstration requires detection and analysis of sequential patterns in a user’s input, and the synthesis of an appropriate structural model that can be used for prediction. This paper describes SEQUITUR, a scheme for inducing a structural description of a sequence from a single example. SEQUITUR integrates several different inference techniques: identification of lexical subsequences or vocabulary elements, hierarchical structuring of such subsequences, identification of elements that have equivalent usage patterns, inference of programming constructs such as looping and branching, generalisation by unifying grammar rules, and the detection of procedural substructure., Although SEQUITUR operates with abstract sequences, a number of concrete illustrations are provided

Extracting text from PostScript

We show how to extract plain text from PostScript files. A textual scan is inadequate because PostScript interpreters can generate characters on the page that do not appear in the source file. Furthermore, word and line breaks are implicit in the graphical rendition, and must be inferred from the positioning of word fragments. We present a robust technique for extracting text and recognizing words and paragraphs. The method uses a standard PostScript interpreter but redefines several PostScript operators, and simple heuristics are employed to locate word and line breaks. The scheme has been used to create a full-text index, and plain-text versions, of 40,000 technical reports (34 Gbyte of PostScript). Other text-extraction systems are reviewed: none offer the same combination of robustness and simplicity

Residual finiteness, QCERF, and fillings of hyperbolic groups

We prove that if every hyperbolic group is residually finite, then every quasi-convex subgroup of every hyperbolic group is separable. The main tool is relatively hyperbolic Dehn filling.Comment: (v1) 22 pages, 2 figures. (v2) 24 pages, 2 figures. An error in the proof and statement of the main technical lemma was corrected, and some other small corrections and clarifications were mad

Organisational forgetting:The food safety risk associated with unintentional knowledge loss

Background: Organisational forgetting is associated with unintentional knowledge loss that makes both food businesses and consumers vulnerable to a food safety incident. It is essential that food businesses have strategies and processes in place to minimise unintentional knowledge loss to ensure that essential knowledge is retained, maintained and stays valid. Scope and approach: The aim of this paper is to consider the risk associated with unintentional food safety knowledge loss at individual, organisational and inter-organisational levels. The research approach employed was to undertake a review of existing literature to frame the conceptual research. Screening of both academic and grey literature demonstrated a distinct knowledge gap i.e., there is limited previous research considering the concept of unintentional knowledge loss and its impact on food safety. Case study examples explore the academic theory in more depth. Key findings and conclusions: Three aspects of organisational forgetting are considered in the context of food safety: organisational amnesia, organisational memory decay, and supply chain déjà-vu. The first two aspects operate at the organisational level and the third at the supply chain level. To overcome the risk of unintentional loss, organisational and interorganisational knowledge needs to be effectively mapped and a knowledge retention policy needs to be developed, implemented and maintained that addresses all types of organisational and interorganisational knowledge, but especially food safety knowledge

Vicarious posttraumatic growth: A systematic literature review

Twenty-eight articles are included in this review, which provides the first comprehensive review of the vicarious posttraumatic growth (VPTG) literature. Five domains are presented. First, assessment methods of VPTG are reviewed; seventeen studies assessed VPTG using a measure designed for use with direct trauma survivors, three used a non-validated measure, and the remaining eight used an open-ended question. Second, the level of similarity between reports of direct and vicarious posttraumatic growth is examined. VPTG was found to be highly similar to direct posttraumatic growth; however, subtle differences between the two were also identified along with manifestations of growth unique to VPTG. Third, a range of psychological, cognitive, behavioural, interpersonal, and external factors that have been implicated to facilitate VPTG are presented. Fourth, research exploring the relationship between VPTG and secondary traumatic stress is examined. Three possible explanations are presented: a positive linear association, no association, and a more complex curvilinear relationship. Finally, limitations to the current body of knowledge and areas for future research are explored

Wildlife conservation in Zambia and the Landsafe Customary Commons

This dissertation both proposes and records the ongoing implementation of a ‘Landsafe’ integrated conservation and development model for the customary commons of Zambia. In Volume I, a geographical historical perspective of the country is presented which concentrates on wildlife conservation and rural people. The changes wrought successively on indigenous peoples by invading native Africans of the Bantu linguistic group, then in turn on them by Europeans in the form of Charter Companies and later by Imperial Protectorate rule, and finally, by self-rule, is explored. The country’s evolution from Western colonialism and embedded liberalism, to exploitative neoliberalism and the concurrent emergence of the traditional patrimonial system - one modernised by its meeting with European captalism, is the backdrop and basis for the construction of Landsafe and its current implementation in two chiefdoms. Volume II presents the Landsafe ICDP model. This is based on the formation of chiefdom statutory trusts, with trustees elected by villagers of the customary commons; and the signing of co-management agreements with government departments in respect of wildlife, Game Management Areas, and protected forest land, forests, fisheries and water. The local District Councils would be signatory to such agreements, and the chiefs and their headmen would vest selected customary land in these trusts. These vested lands are then protected, allowing for controlled exploitation by investors - such that they do not impinge unnecessarily on traditional rights or on the re-establishment of traditional guardians of nature. Land may not, under any circumstances, be alienated from customary control. A log frame programme analysis procedure is adopted and a suggested formalisation methodology and procedures for implementing Landsafe included. Finally, the socio-ecology of the first project area in the Luangwa Valley is detailed, followed by a description of the implementation of the Landsafe programme; including a critical analysis comparing Landsafe theory to practice.Thesis (PhD)--University of Pretoria, 2011.Centre for Wildlife Managementunrestricte

The Relationship Between Medical Diagnoses, Risk Perceptions, and Social Distancing Compliance: An Analysis of Data from the Toledo Adolescent Relationships Study

Background: The health belief model suggests that individuals' beliefs affect behaviors associated with health. This study examined whether Ohioans' pre-existing medical health diagnoses affected their belief about personal health risk and their compliance with social distancing during the coronavirus disease 2019 (COVID-19) pandemic. Prior research examining physical and mental diagnoses and social distancing compliance is nearly nonexistent. We examined whether physical and mental health diagnoses influenced individuals' beliefs that their health is at risk and their adherence with social distancing guidelines. Methods: The study used longitudinal cohort data from the Toledo Adolescent Relationships Study (TARS) (n = 790), which surveyed Ohioans prior to and during the COVID-19 pandemic. Dependent variables included belief that an individual's own health was at risk and social distancing compliance. Independent variables included physical and mental health diagnoses, pandemic-related factors (fear of COVID-19, political beliefs about the pandemic, friends social distance, family social distance, COVID-19 exposure), and sociodemographic variables (age, gender, race/ethnicity, educational level). Results: Individuals who had a pre-existing physical health diagnosis were more likely to believe that their personal health was at risk during the pandemic but were not more likely to comply with social distancing guidelines. In contrast, individuals who had a pre-existing mental health diagnosis were more compliant with social distancing guidelines but were not more likely to believe their personal health was at risk. Individuals who expressed greater fear of COVID-19 believed their health is more at risk than those who expressed lower levels of fear. Conclusion: Health considerations are important to account for in assessments of responses to the pandemic, beliefs about personal health risk, and social distancing behavior. Additional research is needed to understand the divergence in the findings regarding physical health, beliefs about personal health risk, and social distancing compliance. Further, research is needed to understand how mental health issues impact decision-making related to social distancing compliance