Hybrid LEGO-EFIE method applied to antenna problems comprising anisotropic media

Linear embedding via Green’s operators (LEGO) is a domain decomposition method in which complex radiation and scattering problems are modelled and solved by means of interacting electromagnetic "bricks". We propose an extension of LEGO able to handle bodies with anisotropic constitutive parameters and metallic objects (e.g., antennas). Since the anisotropic objects are dealt with LEGO, and the metallic parts are treated with the electric field integral equation (EFIE), we refer to the overall approach as hybrid LEGO-EFIE. The characterization of an electromagnetic brick which embeds an anisotropic object requires solving a volume integral equation (VIE). Since this procedure is carried out for each brick independently, the LEGO approach per se is extremely advantageous over the direct solution of a global VIE for all the bodies at once. Nonetheless, we further mix the hybrid LEGO-EFIE approach with the eigencurrents expansion method in order to tackle relatively larger problems. The technique is used to analyze a reconfigurable plasma antenna array (PAA) comprised of magnetized-plasma tubes placed around a two-dipole antenna array

Solving wave propagation within finite-sized composite media with linear embedding via Green's operators

The calculation of electromagnetic (EM) fields and waves inside finite-sized structures comprised of different media can benefit from a diakoptics method such as linear embedding via Green's operators (LEGO). Unlike scattering problems, the excitation of EM waves within the bulk dielectric requires introducing sources inside the structure itself. To handle such occurrence, we have expanded the set of LEGO sub-domains - employed to formulate an EM problem - to deal with the inclusion of elementary sources. The corresponding subdomains (bricks) play the role of ``generators'' in the equivalent model. Moreover, if a source is ``turned off'', as it were, the enclosing brick can be utilized as a numerical ``probe'' to sample the EM field. In this paper, we present the integral equations of LEGO modified so as to accommodate generator/probe bricks. Numerical results are provided which demonstrate the validity and the efficiency of the approach

Sensitivity analysis of 3-D composite structures through linear embedding via green's operators

We propose a methodology --- based on linear embedding via Green's operators (LEGO) and the eigencurrent expansion method (EEM) --- for solving electromagnetic problems involving large 3-D structures comprised of ND = 1 bodies. In particular, we address the circumstance when the electromagnetic properties or the shape of one body differ from those of the others. In real-life structures such a situation may be either the result of a thoughtful design process or the unwanted outcome of fabrication tolerances. In order to assess the sensitivity of physical observables to localized deviations from the "ideal" structure, we follow a deterministic approach, i.e., we allow for a finite number of different realizations of one of the bodies. Then, for each realization we formulate the problem with LEGO and we employ the EEM to determine the contribution of the ND - 1 "fixed" bodies. Since the latter has to be computed only once, the overall procedure is indeed efficient. As an example of application, we investigate the sensitivity of a 2-layer array of split-ring resonators with respect to the shape and the offset of one element in the array

Electromagnetic modelling of large complex 3-D structures with LEGO and the eigencurrent expansion method

Linear embedding via Green's operators (LEGO) is a computational method in which the multiple scattering between adjacent objects - forming a large composite structure - is determined through the interaction of simple-shaped building domains, whose electromagnetic (EM) behavior is accounted for by means of scattering operators. This method has been successfully demonstrated for 2-D electromagnetic band-gaps (EBG) and other structures, and for very simple 3-D configurations. In this communication we briefly report on the full extension of LEGO to large complex 3-D structures, which may be EBG-based but may also include finite antenna arrays as well as frequency selective surfaces, to name but a few applications. In particular, we shall outline two modifications that were crucial for scaling up the LEGO method, namely, the introduction of a total inverse scattering operator S_1 and the eigencurrent expansion method (EEM)

An eigencurrent approach to the analysis of electrically large 3-D structures using linear embedding via Green's operators

We present an extension of the Linear Embedding via Greens Operators (LEGO) procedure for efficiently dealing with 3-D electromagnetic composite structures. In LEGOs notion, we enclose the objects forming a structure within arbitrarily shaped domains (bricks), which (by invoking the Equivalence Principle) we characterize through scattering operators. In the 2-D instance, we then combined the bricks numerically, in a cascade of successive embedding steps, to build increasingly larger domains and obtain the scattering operator of the whole aggregate of objects. In the 3-D case, however, this process becomes quite soon impracticable, in that the resulting scattering matrices are too big to be stored and handled on most computers. To circumvent this hurdle, we propose a novel formulation of the electromagnetic problem based on an integral equation involving the total inverse scattering operator of the structure, which can be written analytically in terms of scattering operators of the bricks and transfer operators among them. We then solve this equation by the Method of Moments combined with the Eigencurrent Expansion Method, which allows for a considerable reduction in size of the system matrix and thereby enables us to study very large structures

The IGNITOR ICRF system

Sheets presentatio

Intrapancreatic accessory spleen false positive to 68Ga-Dotatoc: case report and literature review

Background: Intrapancreatic accessory spleen (IPAS) is an uncommon finding of pancreatic mass. Differential diagnosis with pancreatic tumor, especially with non-functional neuroendocrine tumor (NF-NET), may be very hard and sometimes it entails unnecessary surgery. A combination of CT scan, MRI, and nuclear medicine can confirm the diagnosis of IPAS. 68-Ga-Dotatoc PET/CT is the gold standard in NET diagnosis and it can allow to distinguish between IPAS and NET. Case presentation: A 69-year-old man was admitted to our hospital for an incidental nodule in the tail of the pancreas with focal uptake of 68-Ga-dotatate at PET/CT. NET was suspected and open distal splenopancreatectomy was performed. Pathologic examination revealed an IPAS. Conclusion: This is the second IPAS case in which a positive 68Ga-Dotatoc uptake led to a false diagnosis of pancreatic NET. Here is a proposal of a literature review

TOPICA/TORIC integration for self-consistent antenna and plasma analysis

Sheets presentatio

Fibrinogen-elongated Chain Inhibits Thrombin-induced Platelet Response, Hindering the Interaction with Different Receptors

The expression of the elongated fibrinogen γ chain, termed γ′, derives from alternative splicing of mRNA and causes an insertion sequence of 20 amino acids. This insertion domain interacts with the anion-binding exosite (ABE)-II of thrombin. This study investigated whether and how γ′ chain binding to ABE-II affects thrombin interaction with its platelet receptors, i.e. glycoprotein Ibα (GpIbα), protease-activated receptor (PAR) 1, and PAR4. Both synthetic γ′ peptide and fibrinogen fragment D*, containing the elongated γ′ chain, inhibited thrombin-induced platelet aggregation up to 70%, with IC50 values of 42 ± 3.5 and 0.47 ± 0.03 μm, respectively. Solid-phase binding and spectrofluorimetric assays showed that both fragment D* and the synthetic γ′ peptide specifically bind to thrombin ABE-II and competitively inhibit the thrombin binding to GpIbα with a mean Ki ≈ 0.5 and ≈35 μm, respectively. Both these γ′ chain-containing ligands allosterically inhibited thrombin cleavage of a synthetic PAR1 peptide, of native PAR1 molecules on intact platelets, and of the synthetic chromogenic peptide d-Phe-pipecolyl-Arg-p-nitroanilide. PAR4 cleavage was unaffected. In summary, fibrinogen γ′ chain binds with high affinity to thrombin and inhibits with combined mechanisms the platelet response to thrombin. Thus, its variations in vivo may affect the hemostatic balance in arterial circulation

Annealing Effects on PECVD-grown Si rich aSiNx Thin Films

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