5,575 research outputs found

    An Object-Oriented Approach to Knowledge Representation in a Biomedical Domain

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    An object-oriented approach has been applied to the different stages involved in developing a knowledge base about insulin metabolism. At an early stage the separation of terminological and assertional knowledge was made. The terminological component was developed by medical experts and represented in CORE. An object-oriented knowledge acquisition process was applied to the assertional knowledge. A frame description is proposed which includes features like states and events, inheritance and collaboration. States and events are formalized with qualitative calculus. The terminological knowledge was very useful in the development of the assertional component. It assisteed in understanding the problem domain, and in the implementation stage, it assisted in building good inheritance hierarchies

    The abortion-crime link: evidence from England and Wales

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    We use panel data from 1983 to 1997 for the 42 police force areas in England and Wales to test the hypothesis that legalizing abortion contributes to lower crime rates. We provide an advance on previous work by focusing on the impact of possible endogeneity of effective abortion rates with respect to crime. Our use of U.K. data allows us to exploit regional differences in the provision of free abortions to identify abortion rates. When we use a similar model and estimation methodology, we are able to replicate the negative association between abortion rates and reported crime found by Donohue and Levitt for the U.S. However, when we allow for the potential endogeneity of effective abortion rates with respect to crime, we find no clear connection between the two.

    The Politics and Analytics of Health Policy

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    Let us start with an example of health policy analysis in action. Within that category of countries loosely known as ‘the West’, quite basic differences exist in attitudes to health policy and also actual health policy. Comparing the US with mainland Europe and indeed Canada, for example, one perceives a difference in attitude on the part of the majority towards collectivism and individualism in access to, provision of and financing of healthcare. The explanation for policy and system differences—for example, between the US healthcare system(s) and the various NHSs of the UK countries (England, Scotland, Wales and Northern Ireland)—is commonly framed in terms of ‘ideology’ but there are also ‘institutional’ explanations (1). Additionally, however, popular attitudes or ‘values’ may be taken as autonomous ‘inputs’ into the explanation (e.g. ‘American values prevent the enactment of an NHS’) or, at least in part, derived from or influenced by institutional reality. If, for example, there is no chance of a bill to establish an NHS or a comprehensive system of public health insurance passing in Washington, then reformers over time trim not only their legislative ambitions, but also their very way of thinking about the issue

    Appeasing the carotid body after chronic intermittent hypoxia

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    Shear bands and cracking of metallic glass plates in bending

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    The thickness dependence of yielding and fracture of metallic glass plates subjected to bending is considered in terms of the shear band processes responsible for these properties. We argue that the shear band spacing (and length) scales with the thickness of the plate because of strain relaxation in the vicinity of the shear band at the surface. This is consistent with recent measurements of shear band spacing versus sample size. We also argue that the shear displacements in the shear band scale with the shear band length and plate thickness, thus causing cracks to be initiated in thicker plates at smaller bending strains. This leads to fracture bending strains that decrease markedly with increasing plate thickness, consistent with recent experiments. These results suggest that amorphous metals in the form of foams might have superior ductility and toughness

    Circumventricular organ apelin receptor knockdown decreases blood pressure and sympathetic drive responses in the spontaneously hypertensive rat

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    The central site(s) mediating the cardiovascular actions of the apelin-apelin receptor (APJ) system remains a major question. We hypothesized that the sensory circumventricular organs (CVOs), interfacing between the circulation and deeper brain structures, are sites where circulating apelin acts as a signal in the central nervous system to decrease blood pressure (BP). We show that APJ gene (aplnr) expression was elevated in the CVOs of spontaneously hypertensive rats (SHRs) compared to normotensive Wistar Kyoto (WKY) controls, and that there was a greater mean arterial BP (MABP) decrease following microinjection of [Pyr(1)]apelin-13 to the CVOs of SHRs compared to WKY rats. Lentiviral APJ-specific-shRNA (LV-APJ-shRNA) was used to knockdown aplnr expression, both collectively in three CVOs and discretely in individual CVOs, of rats implanted with radiotelemeters to measure arterial pressure. LV-APJ-shRNA-injection decreased aplnr expression in the CVOs and abolished MABP responses to microinjection of [Pyr(1)]apelin-13. Chronic knockdown of aplnr in any of the CVOs, collectively or individually, did not affect basal MABP in SHR or WKY rats. Moreover, knockdown of aplnr in any of the CVOs individually did not affect the depressor response to systemic [Pyr(1)]apelin-13. By contrast, multiple knockdown of aplnr in the three CVOs reduced acute cardiovascular responses to peripheral [Pyr(1)]apelin-13 administration in SHR but not WKY rats. These results suggest that endogenous APJ activity in the CVOs has no effect on basal BP but that functional APJ in the CVOs is required for an intact cardiovascular response to peripherally administered apelin in the SHR

    B792: The Development of the Ability to Select for Increased Milk Production: The Jersey Dairy Cow in Maine, 1900-1984

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    Histories of dairying and dairy farming usually pass over one very important topic, the point of origin herself: the dairy cow. In the past 150 years, the period associated with the rise of commercial dairying in the U.S., she has not been a static creature. The story of her development is an important and exciting part of the history of dairying, but this development cannot be explained by such phrases as feeding and management improved or breeding improved . Since the dairy cow of the 1980s is not the same dairy cow of the 1830s, we should understand how this transition occurred and why it is important.https://digitalcommons.library.umaine.edu/aes_bulletin/1128/thumbnail.jp

    Computational Aspects of Protein Functionality

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    The purpose of this short article is to examine certain aspects of protein functionality with relation to some key organizing ideas. This is important from a computational viewpoint in order to take account of modelling both biological systems and knowledge of these systems. We look at some of the lexical dimensions of the function and how certain constructs can be related to underlying ideas. The pervasive computational metaphor is then discussed in relation to protein multifunctionality, and the specific case of von Willebrand factor as a ‘smart’ multifunctional protein is briefly considered. Some diagrammatic techniques are then introduced to better articulate protein function
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