859 research outputs found

    A model-driven method for the systematic literature review of qualitative empirical research

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    This paper explores a model-driven method for systematic literature reviews (SLRs), for use where the empirical studies found in the literature search are based on qualitative research. SLRs are an important component of the evidence-based practice (EBP) paradigm, which is receiving increasing attention in information systems (IS) but has not yet been widely-adopted. We illustrate the model-driven approach to SLRs via an example focused on the use of BPMN (Business Process Modelling Notation) in organizations. We discuss in detail the process followed in using the model-driven SLR method, and show how it is based on a hermeneutic cycle of reading and interpreting, in order to develop and refine a model which synthesizes the research findings of previous qualitative studies. This study can serve as an exemplar for other researchers wishing to carry out model-driven SLRs. We conclude with our reflections on the method and some suggestions for further researc

    THE EFFECTS OF BOATING UPON LEAD CONCENTRATIONS IN FISH

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    The concentration of lead in fish muscle tissue from lakes where boating is heavy and where it is prohibited was measured. The lead levels ranged from less than 0.05 to 1.35 ppm but did not differ significantly between those in the controlled and non-controlled boating lakes. Lead levels apparently pose no public health hazard

    Sequential pattern formation governed by signaling gradients

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    Rhythmic and sequential segmentation of the embryonic body plan is a vital developmental patterning process in all vertebrate species. However, a theoretical framework capturing the emergence of dynamic patterns of gene expression from the interplay of cell oscillations with tissue elongation and shortening and with signaling gradients, is still missing. Here we show that a set of coupled genetic oscillators in an elongating tissue that is regulated by diffusing and advected signaling molecules can account for segmentation as a self-organized patterning process. This system can form a finite number of segments and the dynamics of segmentation and the total number of segments formed depend strongly on kinetic parameters describing tissue elongation and signaling molecules. The model accounts for existing experimental perturbations to signaling gradients, and makes testable predictions about novel perturbations. The variety of different patterns formed in our model can account for the variability of segmentation between different animal species.Comment: 12 pages, 5 figure

    THE EFFECTS OF BOATING UPON LEAD CONCENTRATIONS IN FISH

    Get PDF
    The concentration of lead in fish muscle tissue from lakes where boating is heavy and where it is prohibited was measured. The lead levels ranged from less than 0.05 to 1.35 ppm but did not differ significantly between those in the controlled and non-controlled boating lakes. Lead levels apparently pose no public health hazard

    Are Energy Efficiency Standards Justified?

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    This paper develops and parameterizes an overarching analytical framework to estimate the welfare effects of energy efficiency standards applied to automobiles and electricity-using durables. We also compare standards with sectoral and economywide pricing policies. The model captures a wide range of externalities and preexisting energy policies, and it allows for possible “misperceptions”—market failures that cause underinvestment in energy efficiency.Automobile fuel economy standards are not part of the first-best policy to reduce gasoline: fuel taxes are always superior because they reduce the externalities related to vehicle miles traveled. For the power sector, potential welfare gains from supplementing pricing instruments with efficiency standards are small at best. If pricing instruments are not feasible, a large misperceptions failure is required to justify efficiency standards, and even in this case the optimal reductions in fuel and electricity use are relatively modest. Reducing economywide carbon dioxide emissions through regulatory packages (combining efficiency and emissions standards) involves much higher costs than pricing instruments.standards, energy taxes, market failure, climate, power sector, gasoline

    Microstructural changes as a time temperature indicator in cobalt superalloys and a NiCoCrAlTaY coating

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    Gas turbines in power generation systems use both nickel and cobalt-based superalloys for vanes, blades, discs and combustion chamber components. Cobalt-based superalloys have the advantage over nickel based superalloys in that they have a higher thermal conductivity and hence a greater thermal shock resistance, a greater resistance to thermal fatigue and also a better corrosion resistance. However, in some applications coatings have to be applied to such alloys because of their poor oxidation resistance. The creep strength of cobalt-based superalloys depends primarily on solid solution strengthening and the interaction between the hard carbides and alloy defects, such as dislocations and stacking faults. There is a need to develop an understanding of the microstructural changes that occur in cobalt-based superalloys, with both time and temperature, for life prediction, refurbishment and failure investigations... cont'd

    NODULAR MASSES IN THE SWIMBLADDER AND VISCERAL FAT OF THE WALLEYE, \u3ci\u3eSTIZOSTEDION VITREUM\u3c/i\u3e

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    In April of 1990, a 1.8 kg walleye was found to contain hard cysts or nodules in the swimbladder and visceral fat. The nodules appeared to be formed around a worm-like mass. The nodules (10 ± 5 mm in diameter) were composed of five to seven layers of tightly packed granules, that were at least partially calcified and the layers were held together by a sticky matrix. The outer coat of the nodule was convoluted with many protuberances. This is a first report of such cysts from fish and they appear to be similar to nodules induced by worms (encysted nematodes) in the intestines of swine and ruminants

    BLOOD AND TISSUE IDENTIFICATION OF SELECTED BIRDS AND MAMMALS, PART II: Cross Reaction Patterns of Birds and Mammals, Using Deer, Bovine, Raccoon, Chicken and Mallard Duck Antiserum, part 4

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    Part 4 (pp. 86-114) Mammals (Figure 10), continued Horse Human Mink Opossum Pig Porcupine. Prairie Dog Raccoon Big Horn Sheep Domestic Sheep Striped Skunk Fox Squirrel Discussio

    NODULAR MASSES IN THE SWIMBLADDER AND VISCERAL FAT OF THE WALLEYE, \u3ci\u3eSTIZOSTEDION VITREUM\u3c/i\u3e

    Get PDF
    In April of 1990, a 1.8 kg walleye was found to contain hard cysts or nodules in the swimbladder and visceral fat. The nodules appeared to be formed around a worm-like mass. The nodules (10 ± 5 mm in diameter) were composed of five to seven layers of tightly packed granules, that were at least partially calcified and the layers were held together by a sticky matrix. The outer coat of the nodule was convoluted with many protuberances. This is a first report of such cysts from fish and they appear to be similar to nodules induced by worms (encysted nematodes) in the intestines of swine and ruminants
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