Graph Processing in Main-Memory Column Stores

Evermore, novel and traditional business applications leverage the advantages of a graph data model, such as the offered schema flexibility and an explicit representation of relationships between entities. As a consequence, companies are confronted with the challenge of storing, manipulating, and querying terabytes of graph data for enterprise-critical applications. Although these business applications operate on graph-structured data, they still require direct access to the relational data and typically rely on an RDBMS to keep a single source of truth and access. Existing solutions performing graph operations on business-critical data either use a combination of SQL and application logic or employ a graph data management system. For the first approach, relying solely on SQL results in poor execution performance caused by the functional mismatch between typical graph operations and the relational algebra. To the worse, graph algorithms expose a tremendous variety in structure and functionality caused by their often domain-specific implementations and therefore can be hardly integrated into a database management system other than with custom coding. Since the majority of these enterprise-critical applications exclusively run on relational DBMSs, employing a specialized system for storing and processing graph data is typically not sensible. Besides the maintenance overhead for keeping the systems in sync, combining graph and relational operations is hard to realize as it requires data transfer across system boundaries. A basic ingredient of graph queries and algorithms are traversal operations and are a fundamental component of any database management system that aims at storing, manipulating, and querying graph data. Well-established graph traversal algorithms are standalone implementations relying on optimized data structures. The integration of graph traversals as an operator into a database management system requires a tight integration into the existing database environment and a development of new components, such as a graph topology-aware optimizer and accompanying graph statistics, graph-specific secondary index structures to speedup traversals, and an accompanying graph query language. In this thesis, we introduce and describe GRAPHITE, a hybrid graph-relational data management system. GRAPHITE is a performance-oriented graph data management system as part of an RDBMS allowing to seamlessly combine processing of graph data with relational data in the same system. We propose a columnar storage representation for graph data to leverage the already existing and mature data management and query processing infrastructure of relational database management systems. At the core of GRAPHITE we propose an execution engine solely based on set operations and graph traversals. Our design is driven by the observation that different graph topologies expose different algorithmic requirements to the design of a graph traversal operator. We derive two graph traversal implementations targeting the most common graph topologies and demonstrate how graph-specific statistics can be leveraged to select the optimal physical traversal operator. To accelerate graph traversals, we devise a set of graph-specific, updateable secondary index structures to improve the performance of vertex neighborhood expansion. Finally, we introduce a domain-specific language with an intuitive programming model to extend graph traversals with custom application logic at runtime. We use the LLVM compiler framework to generate efficient code that tightly integrates the user-specified application logic with our highly optimized built-in graph traversal operators. Our experimental evaluation shows that GRAPHITE can outperform native graph management systems by several orders of magnitude while providing all the features of an RDBMS, such as transaction support, backup and recovery, security and user management, effectively providing a promising alternative to specialized graph management systems that lack many of these features and require expensive data replication and maintenance processes

Portraying The Role Of Giuseppe Zangara In Sondheim\u27s Assassins

This thesis is a look at the process an actor goes through in creating a fictional character based on a historical person. It is not intended to be a guide for other actors but instead a look at the work of one particular actor in portraying Giuseppe Zangara in Sondheim and Weidman\u27s Assassins. This thesis consists of historical research, character and script analysis, as well as a personal reflection of the performance

State of stress in piezoelectric elements with interdigitated electrodes

Finite element analyses have been performed on the representative volume element of piezoelectric elements with interdigitated electrodes (IDE). In these investigations the change of the piezoelectric material properties during polarization has been considered prior to additional service loads, e.g. mechanical loading. The numerical results obtained with a specially coded finite element routine are compared with a reference model given by the so called uniform field model. The model indicates stress concentrations at the tip of the finger electrode, which have been validated by experimental results. The modeling approach presented allows for a better understanding of the overall effects in piezoelectric materials with ID

Socio-demographic factors and psychological distress in Indigenous and non-Indigenous Australian adults aged 18-64 years: analysis of national survey data

BackgroundIndigenous Australians are known to be at greater risk of morbidity and mortality from mental health related conditions, but most available data relate to the use of mental health services, and little is known about other aspects of social and emotional wellbeing. Using the first available nationally representative data, we examined the prevalence and patterning of psychological distress among Indigenous Australian adults and compared these with corresponding data from the non-Indigenous population.MethodsThe analysis used weighted data on psychological distress, as measured by a modified Kessler Psychological Distress score (K5), and a range of socio-demographic measures for 5,417 Indigenous and 15,432 non-Indigenous adults aged 18-64 years from two nationally representative surveys. Very high psychological distress (VHPD) was defined as a K5 score ≥ 15 (possible range = 5-25).ResultsIndigenous adults were about three times more likely than non-Indigenous adults to be classified with VHPD: 14.5% (95% confidence interval (CI) 12.9-16.0%) versus 5.5% (95% CI 5.0-5.9%). After adjusting for age, most socio-demographic variables were significantly associated with VHPD in both populations, although the relative odds were generally larger among non-Indigenous people. Indigenous people in remote areas had a lower prevalence of VHPD than their non-remote counterparts, and only marital status, main language, and food insecurity were significantly associated with VHPD in remote areas.ConclusionsHigher absolute levels of VHPD combined with smaller socio-demographic gradients in the Indigenous population suggest the importance of risk factors such as interpersonal racism, marginalization and dispossession, chronic stress and exposure to violence that are experienced by Indigenous Australians with common and/or cross-cutting effects across the socioeconomic spectrum. The lower prevalence of VHPD and lack of association with many socio-demographic variables in remote areas suggests either that the instrument may be less valid for Indigenous people living in remote areas or that living in an Indigenous majority environment (such as exists in most remote communities) may mitigate the risk of psychological distress to some degree

The impact of racism on indigenous health in Australia and Aotearoa: towards a research agenda

It is well established that Indigenous Australians and Māori have higher levels of ill health and mortality than non-Indigenous people. It is also clear that the disadvantage suffered by Indigenous peoples2 is associated with both historical and contemporary racism, colonisation and oppression. Both an ‘adequate state of health’ and ‘freedom from racism’ are rights enshrined in legislation in Australia and Aotearoa (New Zealand).3 Although several recent national and international reports have shown a link between racism and public health, there is little research on this topic in Australia or Aotearoa. In response to this paucity of research, the ‘Racism and Indigenous Health’ symposium was held at The University of Melbourne on 27 November 2007. This event brought together 35 key researchers and policy-makers from Australia and Aotearoa in the area of racism and Indigenous health to discuss recent findings in this field and to set an agenda for future research. The symposium endorsed a cohesive research agenda to advance our understanding of, and our ability to combat, racism as a threat to Indigenous health in Australia and Aotearoa. Five key research questions were identified from the symposium: • What is the prevalence and experience of racism across the life course for Indigenous peoples? • What impact does racism have on Indigenous health across the life course? • How can we appropriately assess systemic racism against Indigenous peoples? • What are the best ways to address systemic racism against Indigenous peoples? • How can an understanding of the ways in which societal systems produce advantage and positive health outcomes for White Australians and Pākehā New Zealanders help improve Indigenous health? These key questions focus on systemic racism, stressing the importance of further research on the prevalence of racism, its impact on Indigenous health and approaches to eliminating it from society. The symposium also highlighted the need to explore the benefits of racial socialisation (i.e. learning about the nature and ubiquity of racism in society) and to find effective ways to combat interpersonal racism against Indigenous peoples. Improvements in health system performance were supported as an approach to addressing systemic racism in health care, and the symposium emphasised the need to systematically estimate the cost of racism to society in Australia and Aotearoa. This discussion paper highlights the vital importance of sound research in endeavours to combat racism as a threat to Indigenous health in Australia and Aotearoa. We hope that this paper will act as an impetus to policy and decision-makers at the national, regional and local levels to engage in efforts to combat racism against Indigenous peoples as a public health intervention

Interventions to improve cultural competency in healthcare: a systematic review of reviews

Cultural competency is a recognized and popular approach to improving the provision of health care to racial/ethnic minority groups in the community with the aim of reducing racial/ethnic health disparities. The aim of this systematic review of reviews is to gather and synthesize existing reviews of studies in the field to form a comprehensive understanding of the current evidence base that can guide future interventions and research in the area