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71.
Nikolaos Politakos Eleftherios Ntoukas Apostolos Avgeropoulos Vahik Krikorian Brian D. Pate Edwin L. Thomas Randal M. Hill 《Journal of Polymer Science.Polymer Physics》2009,47(23):2419-2427
We report the observation of a cubic phase consistent with the double gyroid structure in strongly segregated diblock copolymers of PS‐b‐PDMS over a volume fraction (φPDMS) range of ~0.39 to 0.45. The samples have respective molecular weights of 127 kg/mol and 73 kg/mol and degree of segregation Nχ equal to 187 and 106, respectively, at annealing temperature of 130 °C. It is important to highlight that two out of the total four samples investigated, exhibited hexagonally close packed cylindrical domains of PDMS and alternating lamellae at φPDMS = 0.39 and 0.45, respectively, indicating the possible narrow range of the DG morphology for the specific diblock copolymers. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 2419–2427, 2009 相似文献
72.
Sofia Rangou Apostolos Avgeropoulos 《Journal of polymer science. Part A, Polymer chemistry》2009,47(6):1567-1574
We report the synthesis of two 2nd generation dendritic terpolymers consisting of poly(butadiene) (PB) of 1,4 geometric isomerism, poly(isoprene) (PI) enriched in 3,4 geometric isomerism (at least 55% PI3,4) and polystyrene (PS). The main focus of this work was the synthesis of well‐defined dendritic terpolymers exhibiting high levels of molecular and compositional homogeneity. The preparation of these materials was achieved via anionic polymerization techniques in combination with chlorosilane linking chemistry. The molecular characterization of the intermediate products and the final dendritic materials was accomplished via gel permeation chromatography, membrane osmometry, differential scanning calorimetry, and 1H‐nuclear magnetic resonance spectroscopy, leading to the conclusion that they can be considered model polymers. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1567–1574, 2009 相似文献
73.
We study a system where the service provider offers priority options. We identify the optimal option pricing policy, by deriving the optimal number a customer would buy and the customer’s exercise policy as a function of system congestion, options remaining, time to expiration and possibility of balking. 相似文献
74.
We study resonant CP-violating Einstein-Podolsky-Rosen correlations that may take place in the production and decay of unstable scalar particles at high-energy colliders. We show that as a consequence of unitarity and CPT invariance of the S-matrix, in 2→2 scatterings mediated by mixed scalar particles, at least three linearly independent decay matrices associated with the unstable scalar states are needed to obtain non-zero CP-odd observables that are also odd under C-conjugation. Instead, for the correlated production and decay of two unstable particle systems in 2→4 processes, we find that only two independent decay matrices are sufficient to induce a net non-vanishing CP-violating phenomenon. As an application of this theorem, we present numerical estimates of CP asymmetries for the correlated production and decay of supersymmetric scalar top-anti-top pairs at the LHC, and demonstrate that these could reach values of order one. As a byproduct of our analysis, we develop a novel spinorial trace technique, which enables us to efficiently evaluate lengthy expressions of squared amplitudes describing the resonant scalar transitions. 相似文献
75.
76.
Apostolos P. Labanaris Vahudin Zugor Robert Smiszek Reinhold Nützel Reinhard Kühn Karl Engelhard 《Magnetic resonance imaging》2010
Introduction
The aim of this study is to examine if guided prostate biopsies based on abnormalities detected by conventional and functional endorectal magnetic resonance imaging (MRI) yield a more reliable representation of the radical prostatectomy pathology and to identify probable preoperative clinical variables that stratified patients likely to harbor significant upgrading.Patients and Methods
From April 2004 to April 2009, a review of N=70 patients records diagnosed with prostate cancer by a 3-6 core guided transrectal ultrasound (TRUS) prostate biopsy based on abnormalities detected by conventional and functional endorectal MRI and who subsequently underwent radical prostatectomy and exhibited a significant upgrading was conducted. Additionally, a multivariate analysis with a significant upgrading as the outcome was performed including the following parameters: prostate specific antigen (PSA) level, clinical stage, prostate size and duration from biopsy to radical prostatectomy.Results
A significant upgrading was noted in only 8.5% of patients, with 1.4% exhibiting a significant downgrading and the rest 90.1% exhibiting an exact Gleason score match. No preoperative clinical variables that stratified patients likely to harbour significant upgrading were identified.Conclusions
This type of biopsy method seems to solve the discordance between the biopsy Gleason score and radical prostatectomy pathology regardless of known preoperative clinical variables that can affect it. 相似文献77.
Kostas Kleidis Apostolos Kuiroukidis Polixeni Nerantzi Demetrios B. Papadopoulos 《General Relativity and Gravitation》2010,42(1):31-49
Under a particular choice of the Ernst potential, we solve analytically the Einstein–Maxwell equations to derive a new exact solution depending on five parameters: the mass, the angular-momentum (per unit mass), α, the electromagnetic-field strength, k, the parameter-p and the Kerr-NUT parameter, l. This (Petrov Type D) solution is cylindrically symmetric and represents the curved background around a charged, rotating
cosmic string, surrounded by gravitational and electromagnetic waves, under the influence of the Kerr-NUT parameter. A C-energy
study in the radiation zone suggests that both the incoming and the outgoing radiation is gravitational, strongly focused
around the null direction and preserving its profile. In this case, the absence of the k-parameter from the C-energy implies that, away from the linear defect the electromagnetic field is too weak to contribute
to the energy-content of the cylindrically symmetric space-time under consideration. In order to explain this result, we have
evaluated the Weyl and the Maxwell scalars near the axis of the linear defect and at the spatial infinity. Accordingly, we
have found that the electromagnetic field is concentrated (mainly) in the vicinity of the axis, while falling-off prominently
at large radial distances. However, as long as k ≠ 1, the non-zero Kerr-NUT parameter enhances those scalars, both near the axis and at the spatial infinity, introducing
some sort of gravitomagnetic contribution. 相似文献
78.
In this paper we give a geometric characterization of the cones of toric varieties that are complete intersections. In particular,
we prove that the class of complete intersection cones is the smallest class of cones which is closed under direct sum and
contains all simplex cones. Further, we show that the number of the extreme rays of such a cone, which is less than or equal
to 2n − 2, is exactly 2n − 2 if and only if the cone is a bipyramidal cone, where n > 1 is the dimension of the cone. Finally, we characterize all toric varieties whose associated cones are complete intersection
cones.
Received: 4 July 2005 相似文献
79.
This paper describes a new multilevel procedure that can solve the discrete Navier–Stokes system arising from finite volume discretizations on composite grids, which may consist of more than one level. SIMPLE is used and tested as the smoother, but the multilevel procedure is such that it does not exclude the use of other smoothers. Local refinement is guided by a criterion based on an estimate of the truncation error. The numerical experiments presented test not only the behaviour of the multilevel algebraic solver, but also the efficiency of local refinement based on this particular criterion. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
80.
Benjamin M.D. O’Driscoll Roisin A. Kelly Matthew Shaw Parvaneh Mokarian-Tabari George Liontos Konstantinos Ntetsikas Apostolos Avgeropoulos Nikolay Petkov Michael A. Morris 《European Polymer Journal》2013
The structure of thin microphase-separated polystyrene-block-polydimethylsiloxane (PS–PDMS) films has been studied using state-of-the-art top-down and cross-sectional electron microscopy. This is the first time that the profile of PS–PDMS films has been measured in situ and these measurements allowed us to image the shape of the PDMS domains within the film as well as examine the wetting behavior of the block copolymer film on a variety of substrates. It was found that for each polymer, substrate chemistry and annealing method combination examined, there was a small range of film thicknesses whereby the films exhibited the optimal characteristics of high levels of ordering without dewetting or multilayering. Specifically, the optimum thickness for films treated by thermal annealing was greater than that for the equivalent solvent annealed film; a change that was correlated with morphology variations related to solvent swelling of the solvent annealed films. The surface chemistry also induced changes in the optimum film thickness. Selective surfaces were shown to control whether a PDMS wetting layer was formed or not, leading to either thicker or thinner wetting optimum film thicknesses; while undulating morphologies were observed for less selective surfaces. Concomitant changes in the periodicity were then hypothesized to occur as a result of confinement effects and the selectivity of the surface. 相似文献