1,748 research outputs found

    Thermal Analysis of As-received and Clinically Retrieved Copper-Nickel-Titanium Orthodontic Archwires

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    Objective: To compare as-received copper-nickel-titanium (CuNiTi) archwires to those used in patients by means of differential scanning calorimetry (DSC). Also, the thermal or phase properties of 27°C, 35°C, and 40°C CuNiTi archwires were studied to ascertain if their properties match those indicated by the manufacturer. Materials and Methods: Six wires of 27°C, 35°C, and 40°C CuNiTi were tested as-received, and six each of the 27°C and 35°C wires were examined after use in patients for an average of approximately 9 and 7 weeks, respectively. Segments of archwire were investigated by DSC over the temperature range from −100°C to 150°C at 10°C per minute. Results: There were no significant differences between as-received and clinically used 27°C and 35°C wires for all parameters (heating onset, endset, and enthalpy and cooling onset, endset, and enthalpy), except the 27°C wires exhibited a significant decrease in the heating enthalpy associated with the martensite-to-austenite transition after clinical use. The heating endsets (austenite finish temperatures) of the 27°C and 35°C wires were within 2°C of those claimed by the manufacturer, but the 40°C wires were found to be nearer to 36°C than 40°C. Conclusions: Clinical use of CuNiTi wires resulted in few differences when compared with as-received wires analyzed by DSC. Two temperature varieties of CuNiTi are reasonably within the parameters of those identified by the manufacturer

    Turbulent flux observations and modelling over a shallow lake and a wet grassland in the Nam Co basin, Tibetan Plateau

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    The Tibetan Plateau plays an important role in the global water cycle and is strongly influenced by climate change. While energy and matter fluxes have been more intensely studied over land surfaces, a large proportion of lakes have either been neglected or parameterised with simple bulk approaches. Therefore, turbulent fluxes were measured over wet grassland and a shallow lake with a single eddy-covariance complex at the shoreline in the Nam Co basin in summer 2009. Footprint analysis was used to split observations according to the underlying surface, and two sophisticated surface models were utilised to derive gap-free time series. Results were then compared with observations and simulations from a nearby eddy-covariance station over dry grassland, yielding pronounced differences. Observations and footprint integrated simulations compared well, even for situations with flux contributions including grassland and lake. The accessibility problem for EC measurements on lakes can be overcome by combining standard meteorological measurements at the shoreline with model simulations, only requiring representative estimates of lake surface temperature

    Синтетические и растительные лекарственные средства с эстрогеноподобной активностью

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    Описаны синтетические и растительные соединения с эстрогеноподобной активностью. Рассмотрены механизмы их действия и возможности клинического применения.Описано синтетичні й рослинні сполуки з естрогеноподібною активністю. Розглянуто механізми їх дії та можливості клінічного використання.Synthetic and herbal compounds with estrogen-like activity are described. The mechanisms of their action and possibility of clinical application are discussed

    Neutrino production through hadronic cascades in AGN accretion disks

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    We consider the production of neutrinos in active galactic nuclei (AGN) through hadronic cascades. The initial, high energy nucleons are accelerated in a source above the accretion disk around the central black hole. From the source, the particles diffuse back to the disk and initiate hadronic cascades. The observable output from the cascade are electromagnetic radiation and neutrinos. We use the observed diffuse background X-ray luminosity, which presumably results {}from this process, to predict the diffuse neutrino flux close to existing limits from the Frejus experiment. The resulting neutrino spectrum is E2E^{-2} down to the \GeV region. We discuss modifications of this scenario which reduce the predicted neutrino flux.Comment: 12 Pages, LaTeX, TK 92 0

    On the Origin of the Highest Energy Cosmic Rays

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    We present the results of a new estimation of the photodisintegration and propagation of ultrahigh energy cosmic ray (UHCR) nuclei in intergalactic space. The critical interactions for photodisintegration and energy loss of UHCR nuclei occur with photons of the infrared background radiation (IBR). We have reexamined this problem making use of a new determination of the IBR based on empirical data, primarily from IRAS galaxies, and also collateral information from TeV gamma-ray observations of two nearby BL Lac objects. Our results indicate that a 200 EeV Fe nucleus can propagate apx. 100 Mpc through the IBR. We argue that it is possible that the highest energy cosmic rays observed may be heavy nuclei.Comment: 2 pages revtex with one figure, submitted to Physical Review Letter

    Spinning compact binary inspiral II: Conservative angular dynamics

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    We establish the evolution equations of the set of independent variables characterizing the 2PN rigorous conservative dynamics of a spinning compact binary, with the inclusion of the leading order spin-orbit, spin-spin and mass quadrupole - mass monopole effects, for generic (noncircular, nonspherical) orbits. More specifically, we give a closed system of first order ordinary differential equations for the orbital elements of the osculating ellipse and for the angles characterizing the spin orientations with respect to the osculating orbit. We also prove that (i) the relative angle of the spins stays constant for equal mass black holes, irrespective of their orientation, and (ii) the special configuration of equal mass black holes with equal, but antialigned spins, both laying in the plane of motion (leading to the largest recoil found in numerical simulations) is preserved at 2PN level of accuracy, with leading order spin-orbit, spin-spin and mass quadrupolar contributions included.Comment: v2: 19 pages, extended, improved, published versio
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