An algebraic extension of Dirac quantization: Examples

An extension of the Dirac procedure for the quantization of constrained systems is necessary to address certain issues that are left open in Dirac's original proposal. These issues play an important role especially in the context of non-linear, diffeomorphism invariant theories such as general relativity. Recently, an extension of the required type was proposed by one of us using algebraic quantization methods. In this paper, the key conceptual and technical aspects of the algebraic program are illustrated through a number of finite dimensional examples. The choice of examples and some of the analysis is motivated by certain peculiar problems endemic to quantum gravity. However, prior knowledge of general relativity is not assumed in the main discussion. Indeed, the methods introduced and conclusions arrived at are applicable to any system with first class constraints. In particular, they resolve certain technical issues which are present also in the reduced phase space approach to quantization of these systems.Comment: 43 pages, Latex, CGPG-94/6-1. (References added; particularly to earlier work by C.J.Isham using group theoretic ideas, in the introduction.

Contingent plan structures for spacecraft

Most current AI planners build partially ordered plan structures which delay decisions on action ordering. Such structures cannot easily represent contingent actions. A representation which can is presented. The representation has some other useful features: it provides a good account of the causal structure of a plan, can be used to describe disjunctive actions, and it offers a planner the opportunity of even less commitment than the classical partial order on actions. The use of this representation is demonstrated in an on-board spacecraft activity sequencing problem. Contingent plan execution in a spacecraft context highlights the requirements for a fully disjunctive representation, since communication delays often prohibit extensive ground-based accounting for remotely sensed information and replanning on execution failure

Financial Expertise of Directors

The composition and functioning of corporate boards is at the core of the academic and policy debate on optimal corporate governance. But does board composition matter for corporate decisions? In this paper, we analyze the role of financial experts on boards. In a novel panel data set on board composition, we find that financial experts significantly affect corporate decisions, though not necessarily in the interest of shareholders. First, when commercial bankers join boards, external funding increases and investment-cash flow sensitivity diminishes. But, the increased financing affects mostly firms with good credit and poor investment opportunities. Second, investment bankers on the board are associated with larger bond issues, but also worse acquisitions. Third, we find little evidence that financial expertise matters for compensation policy or for experts without affiliation to a financial institution. The results suggest a tradeoff between outside incentives (e.g. bank profits) and the incentive to maximize firm value. Requiring financial expertise on boards, as mandated by regulatory proposals, may not benefit shareholders if conflicting interests are neglected.

What does validation of cases in electronic record databases mean? The potential contribution of free text

Electronic health records are increasingly used for research. The definition of cases or endpoints often relies on the use of coded diagnostic data, using a pre-selected group of codes. Validation of these cases, as ‘true’ cases of the disease, is crucial. There are, however, ambiguities in what is meant by validation in the context of electronic records. Validation usually implies comparison of a definition against a gold standard of diagnosis and the ability to identify false negatives (‘true’ cases which were not detected) as well as false positives (detected cases which did not have the condition). We argue that two separate concepts of validation are often conflated in existing studies. Firstly, whether the GP thought the patient was suffering from a particular condition (which we term confirmation or internal validation) and secondly, whether the patient really had the condition (external validation). Few studies have the ability to detect false negatives who have not received a diagnostic code. Natural language processing is likely to open up the use of free text within the electronic record which will facilitate both the validation of the coded diagnosis and searching for false negatives

In-Home Counseling for Young Children Living in Poverty: An Exploration of Counseling Competencies

Home-based counseling is increasingly an alternative mode of providing counseling services for children and families, reduces barriers to accessing traditional counseling services, and has also been shown to be effective. As such, the purpose of this qualitative study was to explore and describe the competencies needed to provide such counseling services. This study yielded five categories of competencies—necessary knowledge sets, case conceptualization, counseling behaviors, flexibility in session, and professional dispositions and behaviors. We also outline implications for counseling practice, counselor education, and public policy

Exploring practical approaches to maximising data quality in electronic healthcare records in the primary care setting and associated benefits

Exploiting the information contained within electronic healthcare records (EHR) data will be key to addressing major challenges to public health both nationally and globally, ultimately offering a means of maximising efficiency and equality in care. There are, however, significant challenges in using EHRs effectively and particularly in ensuring the quality of data recorded. Incorrect or missing data could render records as useless or indeed misleading such that conclusions drawn from the data could have a negative impact. Amongst other difficulties, recording data can be time consuming to the extent of conflicting with the GP’s primary focus of patient consultation in an already time-constrained environment. Understanding the requirements of and the demands upon GPs must be central to addressing the issue of data quality (DQ) within EHRs. As part of on-going work into DQ at the Clinical Practice Research Datalink (CPRD) and in collaboration with the University of Sussex (UoS), a workshop session was held at the SAPC (Society for Academic Primary Care) conference in 2014 with the aim of exploring issues of DQ in primary care EHRs from the perspective of different users of GP data and with particular focus on how and why data is recorded in the first instance. The intended outcome was a furthered understanding of both the challenges and the direct benefits to GPs of ensuring high quality data with a view to establishing a workable approach to recording data and maximising benefits to all users of EHRs