19,418 research outputs found

    The accuracy of three-dimensional prediction of soft tissue changes following the surgical correction of facial asymmetry: an innovative concept

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    The accuracy of three-dimensional (3D) predictions of soft tissue changes in the surgical correction of facial asymmetry was evaluated in this study. Preoperative (T1) and 6–12-month postoperative (T2) cone beam computed tomography scans of 13 patients were studied. All patients underwent surgical correction of facial asymmetry as part of a multidisciplinary treatment protocol. The magnitude of the surgical movement was measured; virtual surgery was performed on the preoperative scans using Maxilim software. The predicted soft tissue changes were compared to the actual postoperative appearance (T2). Mean (signed) distances and mean (absolute) distances between the predicted and actual 3D surface meshes for each region were calculated. The one-sample t-test was applied to test the alternative hypothesis that the mean absolute distances had a value of <2.0 mm. A novel directional analysis was applied to analyse the accuracy of the prediction of soft tissue changes. The results showed that the distances between the predicted and actual postoperative soft tissue changes were less than 2.0 mm in all regions. The predicted facial morphology was narrower than the actual surgical changes in the cheek regions. 3D soft tissue prediction using Maxilim software in patients undergoing the correction of facial asymmetry is clinically acceptable

    Nonlinear Discrete Systems with Nonanalytic Dispersion Relations

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    A discrete system of coupled waves (with nonanalytic dispersion relation) is derived in the context of the spectral transform theory for the Ablowitz Ladik spectral problem (discrete version of the Zakharov-Shabat system). This 3-wave evolution problem is a discrete version of the stimulated Raman scattering equations, and it is shown to be solvable for arbitrary boundary value of the two radiation fields and initial value of the medium state. The spectral transform is constructed on the basis of the D-bar approach.Comment: RevTex file, to appear in Journ. Math. Phy

    Pseudo-gap features of intrinsic tunneling in (HgBr_2)-Bi2212 single crystals

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    The c-axis tunneling properties of both pristine Bi2212 and its HgBr2_2 intercalate have been measured in the temperature range 4.2 - 250 K. Lithographically patterned 7-10 unit-cell heigh mesa structures on the surfaces of these single crystals were investigated. Clear SIS-like tunneling curves for current applied in the c\it c-axis direction have been observed. The dynamic conductance dI/I/dV(V)V(V) shows both sharp peaks corresponding to a superconducting gap edge and a dip feature beyond the gap, followed by a wide maximum, which persists up to a room temperature. Shape of the temperature dependence of the {\it c}-axis resistance does not change after the intercalation suggesting that a coupling between CuO2\rm CuO_2-bilayers has little effect on the pseudogap.Comment: 6 pages, 5 figures; presented at the Second Int Conf. New3Sc-1999 (Las Vegas, NV

    Decay of weak solutions to the 2D dissipative quasi-geostrophic equation

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    We address the decay of the norm of weak solutions to the 2D dissipative quasi-geostrophic equation. When the initial data is in L2L^2 only, we prove that the L2L^2 norm tends to zero but with no uniform rate, that is, there are solutions with arbitrarily slow decay. For the initial data in Lp∩L2L^p \cap L^2, with 1≤p<21 \leq p < 2, we are able to obtain a uniform decay rate in L2L^2. We also prove that when the L22α−1L^{\frac{2}{2 \alpha -1}} norm of the initial data is small enough, the LqL^q norms, for q>22α−1q > \frac{2}{2 \alpha -1} have uniform decay rates. This result allows us to prove decay for the LqL^q norms, for q≥22α−1q \geq \frac{2}{2 \alpha -1}, when the initial data is in L2∩L22α−1L^2 \cap L^{\frac{2}{2 \alpha -1}}.Comment: A paragraph describing work by Carrillo and Ferreira proving results directly related to the ones in this paper is added in the Introduction. Rest of the article remains unchange
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