Search results for "fourth"

Malignant teratoma in Klippel-Feil syndrome: a case report and review of the literature

2015

Introduction: Klippel-Feil syndrome is characterized by a congenital fusion of cervical vertebrae. Intracranial teratomas are nongerminomatous germ cell tumors and they account for 0.3 to 0.9% of all intracranial tumors. Teratomas with malignant transformation refer to lesions which give rise to malignant cancer of somatic type. The association between tumors of dermoid origin and Klippel-Feil malformation is extremely rare. Only 23 other cases have so far been reported, and only one case of dermoid tumor with areas of dedifferentiation on squamous cell carcinoma has been described. Case presentation: We report the case of a 72-year-old white man with a 2-year history of gait and balance di…

The role of computed tomography in the diagnosis of brain tumors in infants and children.

1978

CT has considerably facilitated the diagnosis of intracranial tumors, especially in infants and children. The authors review their experience with a series of 260 children with proven brain tumors. In most cases CT is so conclusive that other diagnostic techniques are no longer often needed. Pneumoencephalography in particular has largely been replaced by CT in recent years in the authors' departments, and the frequency of central ventriculography with contrast material has decreased substantially. Particular diagnostic difficulties with regard to tumors near to or within the caudal brain stem, some posterior fossa tumors, small vermian tumors, and tumors of the cerebral hemispheres are dis…

Fourth‐generation glucose sensors composed of copper nanostructures for diabetes management: A critical review

2022

Abstract More than five decades have been invested in understanding glucose biosensors. Yet, this immensely versatile field has continued to gain attention from the scientific world to better understand and diagnose diabetes. However, such extensive work done to improve glucose sensing devices has still not yielded desirable results. Drawbacks like the necessity of the invasive finger‐pricking step and the lack of optimization of diagnostic interventions still need to be considered to improve the testing process of diabetic patients. To upgrade the glucose‐sensing devices and reduce the number of intermediary steps during glucose measurement, fourth‐generation glucose sensors (FGGS) have be…

Strain gradient elasticity within the symmetric BEM formulation

2014

The symmetric Galerkin Boundary Element Method is used to address a class of strain gradient elastic materials featured by a free energy function of the (classical) strain and of its (first) gradient. With respect to the classical elasticity, additional response variables intervene, such as the normal derivative of the displacements on the boundary, and the work-coniugate double tractions. The fundamental solutions - featuring a fourth order partial differential equations (PDEs) system - exhibit singularities which in 2D may be of the order 1/ r 4 . New techniques are developed, which allow the elimination of most of the latter singularities. The present paper has to be intended as a resear…

Fixed point results under generalized c-distance with application to nonlinear fourth-order differential equation

2019

We consider the notion of generalized c-distance in the setting of ordered cone b-metric spaces and obtain some new fixed point results. Our results provide a more general statement, under which can be unified some theorems of the existing literature. In particular, we refer to the results of Sintunavarat et al. [W. Sintunavarat, Y.J. Cho, P. Kumam, Common fixed point theorems for c-distance in ordered cone metric spaces, Comput. Math. Appl. 62 (2011) 1969-1978]. Some examples and an application to nonlinear fourth-order differential equation are given to support the theory.

2014

Background and Purpose In 2007, the WHO classification of brain tumors was extended by three new entities of glioneuronal tumors: papillary glioneuronal tumor (PGNT), rosette-forming glioneuronal tumor of the fourth ventricle (RGNT) and glioneuronal tumor with neuropil-like islands (GNTNI). Focusing on clinical characteristics and outcome, the authors performed a comprehensive individual patient data (IPD) meta-analysis of the cases reported in literature until December 2012.

Dysembryoplastic Neuroepithelial Tumor of the Brainstem

2007

Dysembryoplastic neuroepithelial tumor (DNT) is a clinically benign stable lesion, most frequently located in the temporal and frontal lobes, often responsible for epilepsy in young adults. We describe an unusual case of DNT in the brainstem of a 45-year-old woman. Brain MRI showed a multicystic-like lesion localized in the left inferior pons, involving the ipsilateral cerebellar peduncle and partially dislocating the fourth ventricle. The specific pattern of MRI and CT appearance of DNT and its benign course (our patient is clinically stable with unchanged MRI images at two year follow-up) may help differentiate this tumor from other lesions, i.e. ganglioglio-mas and glioneural malformati…

On the convergence of perturbative coupled cluster triples expansions:Error cancellations in the CCSD(T) model and the importance of amplitude relaxa…

2015

Recently, we proposed a novel Lagrangian-based perturbation series-the CCSD(T-n) series-which systematically corrects the coupled cluster singles and doubles (CCSD) energy in orders of the Møller-Plesset fluctuation potential for effects due to triple excitations. In the present study, we report numerical results for the CCSD(T-n) series up through fourth order which show the predicted convergence trend throughout the series towards the energy of its target, the coupled cluster singles, doubles, and triples (CCSDT) model. Since effects due to the relaxation of the CCSD singles and doubles amplitudes enter the CCSD(T-n) series at fourth order (the CCSD(T-4) model), we are able to separate th…

Direct perturbation theory in terms of energy derivatives: Fourth-order relativistic corrections at the Hartree–Fock level

2011

In this work, the quantum-chemical treatment of relativistic effects by means of direct perturbation theory is extended from its lowest order, DPT2, to the next higher order, DPT4. The required theory is given in terms of energy derivatives with the DPT4 energy correction defined as the corresponding second derivative with respect to the relativistic perturbation parameter λ(rel) = c(2) and c as the speed of light. To facilitate the implementation in standard quantum-chemical program packages, a general formulation of DPT starting from a nonrelativistic Lagrangian is developed, thereby expanding both wave function and operators in terms of λ(rel). The corresponding expressions, which incorp…

Natural fourth generation of leptons

2009

We consider implications of a fourth generation of leptons, allowing for the most general mass patterns for the fourth generation neutrino. We determine the constraints due to the precision electroweak measurements and outline the signatures to search for at the LHC experiments. As a concrete framework to apply these results we consider the minimal walking technicolor (MWTC) model where the matter content, regarding the electroweak quantum numbers, corresponds to a fourth generation.