3,226 research outputs found

    Novel intelligent wavelet filtering of embolic signals from TCD ultrasound

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    Transcranial Doppler ultrasound can be used to detect emboli in blood flow for predicting stroke. Embolic signals have characteristic transient chirps suitable for wavelet analysis. We have implemented and evaluated the first on-line intelligent wavelet filter to amplify embolic signals building on our previous work in detection. Our intelligent wavelet amplifier uses the matching filter properties of the Daubechies 8th order wavelet to amplify embolic signals. Even the smallest embolic signal is enhanced without affecting the background blood flow signal. We show an increase of over 2db (on average) in embolic signal strength and an improvement in detection of 10-20%

    Fluctuations of thermal conductivity and morphological stability

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    Compositional fluctuations of the binary alloy result in the corresponding fluctuations of the thermal conductivity of the material. During crystal growth, these fluctuations can significantly modify the local temperature fields at the liquid-solid interface. This, in turn, will affect the morphological stability of the growing interface. In this work, the temperature dependence of the thermal conductivity of the solid phase has been included into the Mullins-Sekerka formalism. A significant effect on the onset of the instability of planar interface has been predicted. It has been found, in particular, that for binary systems with the segregation coefficient above unity a flat interface is always unstable. The shape of the interface fluctuation should have a single harmonic character with a well defined wavelength

    Initial development of a high-pressure crystal growth facility: Center director's discretionary fund

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    A low-cost, flexible, high-pressure (600 psi) system for crystal growth and related thermophysical properties measurements was designed, assembled, and tested. The furnace system includes a magnetically coupled translation mechanism that eliminates the need for a high-pressure mechanical feedthru. The system is currently being used for continuing crystal growth experiments and thermophysical properties measurements on several material systems including Hg(1-x)Cd(x)Te, Hg(1-x)Zn(x)Te, and Hg(1-x)Zn(x)Se

    The Dutch version of the Child Posttraumatic Cognitions Inventory:validation in a clinical sample and a school sample

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    With the inclusion of trauma-related cognitions in the DSM-5 criteria for posttraumatic stress disorder (PTSD), the assessment of these cognitions has become essential. Therefore, valid tools for the assessment of these cognitions are warranted

    Movement of Ericaphis fimbriata (Hemiptera: Aphididae) apterae on blueberry

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    Blueberry scorch Virus is a new and important pathogen of blueberry in British Columbia, Canada of which the blueberry-infesting aphid Ericaphis fimbriata is a known Vector. In a study of the movement of apterous E. fimbriata, significantly more aphids fell when one ladybird beetle was added to E. fimbriata infested blueberry branches than when zero, two, or four were added. Similar numbers of aphids fell in the presence or absence of beetles at low aphid density (10-30 aphids per terminal), but more fell in the presence of beetles at high aphid density (50-70 aphids per terminal). The time taken for aphids to move a minimum distance of 60 cm off infested plants onto uninfested plants decreased with increasing aphid density which has important implications for the spread of the Virus

    Modelling of the Occurrence of Hydrogen Sulphide in Coal Seams

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    Hydrogen Sulphide (H2S) has been encountered within a number of Bowen Basin collieries, Central Queensland, Australia. High concentration occurrence during mining of a longwall panel raises a number of potential problems, which demand greater understanding to allow efficient mining while maintaining safe and healthy environmental conditions. Longwall panels at Mine A and Mine B have recently mined through H2S zones. The high H2S zone mined through at Mine A was wide and covering the whole length of the face comparing to the narrow H2S zone which was cutting the panel at 45° at Mine B. Longwall panels had been sampled for H2S in pre-mining phases with vertical and inseam exploration boreholes and rib sampling of gateroad development headings. During mining face coal samples were collected in an intensive program and tested in a drum tumbler to determine an indicated seam concentration level through contouring that could be used to calculate the concentrations of H2S liberated to the atmosphere. Data was analysed to determine a geostatistical method, which would best represent the indicated seam concentration level from the given data and the block dimension of the data set. This study discusses the different sampling methods used, selection of the most suitable geostatistical method and the impact of grid size on results of data analysis. Some general observations are made correlating indicated seam H2S concentrations from production face sampling with both predictions made from exploration and liberation rates during mining of the longwall panel

    Introduction. Human perspectives on the quest for knowledge

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    We firstly introduce the new Springer series Human Perspectives in Health Sciences and Technology (HPHST), and then we move on to illustrate the topic this volume deals with, namely whether machines will replace scientists in scientific development. We then explain the decision of having this volume to be the first volume of the HPHST series. Finally, we describe the organization of this book and give a brief presentation of each chapter

    High Speed Production of Large Coal to Facilitate Easier and More Effective Cleaning

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    Track I: Power GenerationIncludes audio file (14 min.)Due to technical difficulties, the audio portion of this presentation is joined in progress.Most modern mining equipment extracts coal through grinding it from the solid using a set of rotating picks. This produces coal that is quite small in average size and generates a lot of dust in the process. The coal is also more expensive to collect and process to remove contained undesirable components. The use of high-pressure water jets as a cutting tool has been shown to provide a product that is larger in size, while con-commitantly eliminating the generation of dust (which carries with it the risk of ignition and explosion) and reducing the energy required for the mining process. Two different mining machines are described, one for use on longwall faces and one in room and pillar mines, and the potential for their development is discussed

    The Influence of Reduced Gravity on the Crystal Growth of Electronic Materials

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    The imperfections in the grown crystals of electronic materials, such as compositional nonuniformity, dopant segregation and crystalline structural defects, are detrimental to the performance of the opto-electronic devices. Some of these imperfections can be attributed to effects caused by Earth gravity during crystal growth process and four areas have been identified as the uniqueness of material processing in reduced gravity environment. The significant results of early flight experiments, i.e. prior to space shuttle era, are briefly reviewed followed by an elaborated review on the recent flight experiments conducted on shuttle missions. The results are presented for two major growth methods of electronic materials: melt and vapor growth. The use of an applied magnetic field in the melt growth of electrically conductive melts on Earth to simulate the conditions of reduced gravity has been investigated and it is believed that the superimposed effect of moderate magnetic fields and the reduced gravity environment of space can result in reduction of convective intensities to the extent unreachable by the exclusive use of magnet on Earth or space processing. In the Discussions section each of the significant results of the flight experiments is attributed to one of the four effects of reduced gravity and the unresolved problems on the measured mass fluxes in some of the vapor transport flight experiments are discussed

    Sharing Supermodular Costs

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    We study cooperative games with supermodular costs. We show that supermodular costs arise in a variety of situations; in particular, we show that the problem of minimizing a linear function over a supermodular polyhedron—a problem that often arises in combinatorial optimization—has supermodular optimal costs. In addition, we examine the computational complexity of the least core and least core value of supermodular cost cooperative games. We show that the problem of computing the least core value of these games is strongly NP-hard and, in fact, is inapproximable within a factor strictly less than 17/16 unless P = NP. For a particular class of supermodular cost cooperative games that arises from a scheduling problem, we show that the Shapley value—which, in this case, is computable in polynomial time—is in the least core, while computing the least core value is NP-hard.National Science Foundation (U.S.) (DMI-0426686
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