865 research outputs found

    A coding theoretic approach to extending designs

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    AbstractWe introduce the study of designs in a coset of a binary code which can be held by vectors of a fixed weight. If C is a binary [2n, n, d] code with n odd and the words of weights n - 1 and n + 1 hold complementary t-designs, then we show that the vectors of weight n in a coset of weight 1 also hold a t-design. We also show how to “extend” these designs. We then consider designs in cosets of type I self-dual codes, in particular in the shadow. If the vectors of a fixed weight in the code hold t-designs then so do the vectors of a fixed weight in the shadow. For [24k - 2, 12k - 1, 2 + 4k] type I codes, these designs extend to designs in the type II parent code

    Etiology of pure tricuspid regurgitation based on anular circumference and leaflet area: Analysis of 45 necropsy patients with clinical and morphologic evidence of pure tricuspid regurgitation

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    Despite recent renewed interest in the detection of tricuspid valve regurgitation by echocardiographic and Doppler techniques, little morphologic information is available on dysfunctioning tricuspid valves. This report describes 45 necropsy patients with clinical and morphologic evidence of pure(no element of stenosis) tricuspid regurgitation and provides morphometric observations (anular circumference, leaflet area) of the tricuspid valve useful in determining the etiology of pure tricuspid regurgitation. Of 45 patients, 24 (53%) had pure tricuspid regurgitation resulting from an anatomically abnormal valve (prolap9e in 7, papillary muscle dysfunction in 6, rheumatic disease in 5, Ebstein's anomaly in 3, infective endocarditis in 2, carcinoid tumor in 1), and 21(47%) had an anatomically normal valve with systolic pulmonary artery hypertension (cor pulmonary in 12, mitral stenosis in 9). Anular circumference was dilated (> 12 cm) in patients with various causes of pulmonary hypertension, floppy valve and Ebstein's tricuspid anomaly. Leaflet area was increased in floppy valve and Ebstein's anomaly.Of the 45 patients, 24 had pulmonary systolic artery pressure measurements available for correlation with tricuspid valve morphology. Pulmonary artery pressures accurately predicted morphologically normal from abnormal valves in 16 patients (89 %). Morphologic overlap occurred in six patients with pulmonary pressures of 41 to 54 mm Hg. Of these six, the additional knowledge of normal or dilated anular circumference correctly separated valves with normal and abnormal leaflets

    Ten questions concerning integrating smart buildings into the smart grid

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    Recent advances in information and communications technology (ICT) have initiated development of a smart electrical grid and smart buildings. Buildings consume a large portion of the total electricity production worldwide, and to fully develop a smart grid they must be integrated with that grid. Buildings can now be ‘prosumers’ on the grid (both producers and consumers), and the continued growth of distributed renewable energy generation is raising new challenges in terms of grid stability over various time scales. Buildings can contribute to grid stability by managing their overall electrical demand in response to current conditions. Facility managers must balance demand response requests by grid operators with energy needed to maintain smooth building operations. For example, maintaining thermal comfort within an occupied building requires energy and, thus an optimized solution balancing energy use with indoor environmental quality (adequate thermal comfort, lighting, etc.) is needed. Successful integration of buildings and their systems with the grid also requires interoperable data exchange. However, the adoption and integration of newer control and communication technologies into buildings can be problematic with older legacy HVAC and building control systems. Public policy and economic structures have not kept up with the technical developments that have given rise to the budding smart grid, and further developments are needed in both technical and non-technical areas

    Is diversity good?

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    Prominent ethical and policy issues such as affirmative action and female enrollment in science and engineering revolve around the idea that diversity is good. However, even though diversity is an ambiguous concept, a precise definition is seldom provided. We show that diversity may be construed as a factual description, a craving for symmetry, an intrinsic good, an instrumental good, a symptom, or a side effect. These acceptions differ vastly in their nature and properties. The first one cannot lead to any action and the second one is mistaken. Diversity as intrinsic good is a mere opinion, which cannot be concretely applied; moreover, the most commonly invoked forms of diversity (sexual and racial) are not intrinsically good. On the other hand, diversity as instrumental good can be evaluated empirically and can give rise to policies, but these may be very weak. Finally, symptoms and side effects are not actually about diversity. We consider the example of female enrollment in science and engineering, interpreting the various arguments found in the literature in light of this polysemy. Keywords: ethics, policy, higher education, female students, minority students, affirmative actionComment: 7 page
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