Search results for "Poster"

Reduced striatal dopamine transporter binding in posterior cortical atrophy

2010

Quasi-Newton approach to nonnegative image restorations

2000

Abstract Image restoration, or deblurring, is the process of attempting to correct for degradation in a recorded image. Typically the blurring system is assumed to be linear and spatially invariant, and fast Fourier transform (FFT) based schemes result in efficient computational image restoration methods. However, real images have properties that cannot always be handled by linear methods. In particular, an image consists of positive light intensities, and thus a nonnegativity constraint should be enforced. This constraint and other ways of incorporating a priori information have been suggested in various applications, and can lead to substantial improvements in the reconstructions. Neverth…

Removal of a migrated dental implant from a maxillary sinus through an intraoral approach: A case report

2021

Background The replacement of maxillary posterior teeth often challenges the clinician due to bone resorption after dental exodontia and low bone quality. Currently, attempts are being made to shorten treatment times by placing implants simultaneously to sinus lift procedures in borderline cases, which can lead to complications such as displacement of implants into the maxillary sinus. Clinical case A 54-year-old patient who was planned for complete rehabilitation of the maxilla through a fixed implant-supported prosthesis on 6 implants. At the level of the 3rd sextant, a sinus lift was performed with a lateral window approach (Caldwell-Luc type) and the simultaneous placement of two implan…

Pneumocisternographic exploration of the posterior fossa

1958

A method previously proposed by the Author for the pneumographic visualization of the posterior fossa has been utilized for the study of several cases. Of these some are reported in this paper. The indications and the advantages of the method are discussed.

Time multiplexing super-resolved imaging without a priori knowledge of the spatial distribution of the encoding structured illumination

2021

Time multiplexing is a super-resolution technique that sacrifices time to overcome the resolution reduction obtained because of diffraction. There are many super resolution methods based on time multiplexing, but all of them require a priori knowledge of the time changing encoding mask, which is projected on the object and used to encode and decode the high-resolution information. In this paper, we present a time multiplexing technique that does not require the a priori knowledge on the projected encoding mask. First, the theoretical concept of the technique is demonstrated; then, numerical simulations and experimental results are presented.

Functional A Posteriori Error Estimate for a Nonsymmetric Stationary Diffusion Problem

2015

In this paper, a posteriori error estimates of functional type for a stationary diffusion problem with nonsymmetric coefficients are derived. The estimate is guaranteed and does not depend on any particular numerical method. An algorithm for the global minimization of the error estimate with respect to an auxiliary function over some finite dimensional subspace is presented. In numerical tests, global minimization is done over the subspace generated by Raviart-Thomas elements. The improvement of the error bound due to the p-refinement of these spaces is investigated.

Existence and asymptotic properties for quasilinear elliptic equations with gradient dependence

2016

Abstract The paper focuses on a Dirichlet problem driven by the ( p , q ) -Laplacian containing a parameter μ > 0 in the principal part of the elliptic equation and a (convection) term fully depending on the solution and its gradient. Existence of solutions, uniqueness, a priori estimates, and asymptotic properties as μ → 0 and μ → ∞ are established under suitable conditions.

Guaranteed error bounds for a class of Picard-Lindelöf iteration methods

2013

We present a new version of the Picard-Lindelof method for ordinary dif- ¨ ferential equations (ODEs) supplied with guaranteed and explicitly computable upper bounds of an approximation error. The upper bounds are based on the Ostrowski estimates and the Banach fixed point theorem for contractive operators. The estimates derived in the paper take into account interpolation and integration errors and, therefore, provide objective information on the accuracy of computed approximations. peerReviewed

Guaranteed and computable error bounds for approximations constructed by an iterative decoupling of the Biot problem

2021

The paper is concerned with guaranteed a posteriori error estimates for a class of evolutionary problems related to poroelastic media governed by the quasi-static linear Biot equations. The system is decoupled by employing the fixed-stress split scheme, which leads to an iteratively solved semi-discrete system. The error bounds are derived by combining a posteriori estimates for contractive mappings with functional type error control for elliptic partial differential equations. The estimates are applicable to any approximation in the admissible functional space and are independent of the discretization method. They are fully computable, do not contain mesh-dependent constants, and provide r…

On the tail ofErrivaspisand the condition of the caudal fin in heterostracans

2009

Articulated caudal fins of heterostracans are preserved in very rare cases. Their morphology and internal structure are completely unknown for the majority of species. One of the few preserved caudal fins belongs to the Early Devonian pteraspidid Errivaspis waynensis from the Welsh Borderland, UK. There are two different reconstructions of the tail: (1) strongly asymmetric, with a considerably longer ventral lobe, and a rather concave posterior margin (e.g. White 1935); and (2) almost symmetrical with an only slightly longer ventral lobe and a small notch in the posterior margin (e.g. Blieck 1984). A new reconstruction of the Errivaspis caudal fin, based on a detailed study of White's speci…