Enhanced Design of Narrowband Filters Based on The Extraordinary Transmission Through Single Fishnet Structures

A systematic method for the efficient design of narrowband filters founded on the extraordinary transmission via single fishnet structures (SFSs) is presented in this paper. Essentially, due to its strong resonant behavior, this phenomenon is proven suitable for the implementation of high-Q devices. The new design formulas are derived through the combination of full-wave numerical simulations and curve fitting algorithms. Also, adequate mathematical criteria are defined for the evaluation of the filters\u27 linear performance, indicating that the transmitted electromagnetic waves remain practically undistorted in the frequency band of interest. Then, by exploiting the previously developed relations, proper correction factors are introduced in the existing SFS equivalent circuit expressions, which hardly increase the overall computational complexity. This quantitative modification leads to an enhanced characterization of SFSs, as key components for diverse applications. Finally, several limitations as well as possible ways of extending the featured algorithm to more complicated structures and higher frequency bands are briefly discussed

A new medication-based prediction score for postoperative delirium in surgical patients: development and proof of feasibility in a retrospective patient cohort

Structured risk screening for postoperative delirium (POD) considering prehospital medication is not established. We aimed to develop a POD-risk prediction score based on known risk factors and delirium-risk increasing drugs to be used by pharmacists during medication reconciliation at hospital admission, and to test for feasibility in a retrospective cohort of surgical patients. Therefore, established POD-risk factors and drugs were extracted from the literature and a score was generated. Following this, the score was tested for feasibility in a retrospective 3-month-cohort of surgical patients. For patients with higher scores suggesting higher probability of POD, patient charts were screened for documentation of POD. For development of the score, the following POD-risk factors were defined and points assigned for score calculation: age (≥65 years=1 point/≥75 years=2), male sex (1), renal insufficiency (RI; 1), hepatic impairment (HI; Model-of-endstage-liver-disease (MELD) 10-14=1/≥15=2), delirium-risk increasing drugs (1 point per drug class), anticholinergic drug burden (ACB; ≥3=1). In the retrospective test cohort of 1174 surgical patients these factors concerned: age ≥65 years 567 patients (48%)/≥75 years 303 (26%), male 652 (55%), RI 238 (20%), MELD 10-14 106 (9%)/≥15 65 (5%), ≥ 1 delirium-risk increasing drug 418 (36%), ACB ≥3 106 (9%). The median POD-risk prediction score was 2 (range 0-9). Of 146 patients (12%) with a score ≥ 5, POD was documented for 43 (30%), no evidence for POD for 91 (62%) and data inconclusive for 12 (8%). For scores of ≥ 7, POD was documented for 50% of the patients with sufficient POD documentation. Overall, POD documentation was poor. To summarize, we developed and successfully tested the feasibility of a POD-prediction-score assessable by pharmacists at medication reconciliation at hospital admission

Polarizability Matrix Extraction of a Bianisotropic Metamaterial from the Scattering Parameters of Normally Incident Plane Waves

In this paper, a polarizability matrix retrieval method for bianisotropic metamaterials is presented. Assuming that scatterers can be modeled by electric and magnetic pointdipoles located at their centers, the induced dipole moments are analytically related to the normally incident fields, while the scattered fields are also analytically obtained for two individual cases of normal wave incidence. The latter can be combined with the incident fields, to express the desired polarizabilities, with regard to the measured or simulated scattering parameters. In this way, the polarizability matrix can be extracted by solving the resulting non-linear system of equations. The proposed technique is applied to two different split-ring resonator structures and reveals very good agreement with previously reported techniques

Polarizability Matrix Extraction of a Bianisotropic Metamaterial from the Scattering Parameters of Normally Incident Plane Waves

In this paper, a polarizability matrix retrieval method for bianisotropic metamaterials is presented. Assuming that scatterers can be modeled by electric and magnetic pointdipoles located at their centers, the induced dipole moments are analytically related to the normally incident fields, while the scattered fields are also analytically obtained for two individual cases of normal wave incidence. The latter can be combined with the incident fields, to express the desired polarizabilities, with regard to the measured or simulated scattering parameters. In this way, the polarizability matrix can be extracted by solving the resulting non-linear system of equations. The proposed technique is applied to two different split-ring resonator structures and reveals very good agreement with previously reported techniques

DGP Cosmology with a Non-Minimally Coupled Scalar Field on the Brane

We construct a DGP inspired braneworld scenario where a scalar field non-minimally coupled to the induced Ricci curvature is present on the brane. First we investigate the status of gravitational potential with non-minimal coupling and observational constraints on this non-minimal model. Then we further deepen the idea of embedding of FRW cosmology in this non-minimal setup. Cosmological implications of this scenario are examined with details and the quintessence and late-time expansion of the universe within this framework are examined. Some observational constraints imposed on this non-minimal scenario are studied and relation of this model with dark radiation formalism is determined with details.Comment: 26 pages, 3 eps figure

Brane Cosmology with a Non-Minimally Coupled Bulk-Scalar Field

We consider the cosmological evolution of a brane in the presence of a bulk scalar field coupled to the Ricci scalar through a term f(\phi)R. We derive the generalized Friedmann equation on the brane in the presence of arbitrary brane and bulk-matter, as well as the scalar field equation, allowing for a general scalar potential V(phi). We focus on a quadratic form of the above non-minimal coupling and obtain a class of late-time solutions for the scale factor and the scalar field on the brane that exhibit accelerated expansion for a range of the non-minimal coupling parameter.Comment: 15 page

Reconstruction of the Scalar-Tensor Lagrangian from a LCDM Background and Noether Symmetry

We consider scalar-tensor theories and reconstruct their potential U(\Phi) and coupling F(\Phi) by demanding a background LCDM cosmology. In particular we impose a background cosmic history H(z) provided by the usual flat LCDM parameterization through the radiation (w_{eff}=1/3), matter (w_{eff}=0) and deSitter (w_{eff}=-1) eras. The cosmological dynamical system which is constrained to obey the LCDM cosmic history presents five critical points in each era, one of which corresponding to the standard General Relativity (GR). In the cases that differ from GR, the reconstructed coupling and potential are of the form F(\Phi)\sim \Phi^2 and U(\Phi)\sim F(\Phi)^m where m is a constant. This class of scalar tensor theories is also theoretically motivated by a completely independent approach: imposing maximal Noether symmetry on the scalar-tensor Lagrangian. This approach provides independently: i) the form of the coupling and the potential as F(\Phi)\sim \Phi^2 and U(\Phi)\sim F(\Phi)^m, ii) a conserved charge related to the potential and the coupling and iii) allows the derivation of exact solutions by first integrals of motion.Comment: Added comments, discussion, references. 15 revtex pages, 5 fugure