Conformal transformation in bowtie nanoantennas and nanocavities: unveiling hidden symmetries

In this work, bowtie nanoantennas and nanocavities are analyzed using the conformal transformation technique. Their performance is studied in terms of the non-radiative Purcell enhancement and self-induced optical forces experienced by quantum emitters. It is demonstrated how these two geometrically different plasmonic nanoparticles can share the same non-radiative Purcell spectra. This hidden symmetric response is unveiled by properly applying the conformal transformation technique, demonstrating that both nanoparticles share the same transformed geometry

Zoned near-zero refractive index fishnet lens antenna: Steering millimeter waves

The following article appeared in Pacheco-Pena, V., Orazbayev, B., Beaskoetxea, U., Beruete, M., & Navarro-Cia, M. (n.d). Zoned near-zero refractive index fishnet lens antenna: Steering millimeter waves. Journal Of Applied Physics, 115(12), and may be found at http://dx.doi.org/10.1063/1.4869436.A zoned fishnet metamaterial lens is designed, fabricated, and experimentally demonstrated at millimeter wavelengths to work as a negative near-zero refractive index lens suitable for compact lens antenna configurations. At the design frequency f=56.7GHz (wavelength = 5.29 mm), the zoned fishnet metamaterial lens, designed to have a focal length FL= 9 wavelengths, exhibits a refractive index n = 0.25. The focusing performance of the diffractive optical element is briefly compared with that of a non-zoned fishnet metamaterial lens and an isotropic homogeneous zoned lens made of a material with the same refractive index. Experimental and numerically-computed radiation diagrams of the fabricated zoned lens are presented and compared in detail with that of a simulated non-zoned lens. Simulation and experimental results are in good agreement, demonstrating an enhancement generated by the zoned lens of 10.7 dB, corresponding to a gain of 12.26 dB. Moreover, beam steering capability of the structure by shifting the feeder on the xz-plane is demonstrated.This work was supported in part by the Spanish Government under contract Consolider Engineering Metamaterials CSD2008-00066 and Contract No. TEC2011- 28664-C02-01. V.P.-P. is sponsored by Spanish Ministerio de Educacion, Cultura y Deporte under Grant No. FPU AP- 2012-3796. B.O. is sponsored by Spanish Ministerio de Economıa y Competitividad under Grant No. FPI BES-2012- 054909. M.B. is sponsored by the Spanish Government via RYC-2011-08221. M. N.-C. is supported by the Imperial College Junior Research Fellowship

Understanding Bowtie Nanoantennas Excited by a Localized Emitter

A full analytical description of a bowtie nanoantenna excited by a localized emitter is presented using the transformation electromagnetic technique. By applying the conformal mapping, the bowtie nanoantenna is transformed into a periodic multi-parallel plate transmission line problem which can be easily evaluated analytically providing physical insight of the coupling between the dipole nanoemitter and the bowtie nanoantenna. The non-radiative Purcell enhancement spectrum is evaluated both analytically and numerically for different lengths, arm angles and metals, demonstrating a good agreement between both approaches. The method here presented fills the gap of the design techniques for optical nanoantennas

Multiplex PCR assay for identification of Corynebacterium pseudotuberculosis from pure cultures and for rapid detection of this pathogen in clinical samples.

Abstract: Corynebacterium pseudotuberculosis is the aetiological agent of caseous lymphadenitis (CLA), a debilitating disease of sheep and goats. Accurate diagnosis of CLA primarily relies on microbiological examination, followed by biochemical identification of isolates. In an effort to facilitate C. pseudotuberculosis detection, a multiplex PCR (mPCR) assay was developed targeting three genes of this bacterium: the 16S rRNA gene, rpoB and pld. This method allowed efficient identification of 40 isolates of this bacterium that had been identified previously by biochemical testing. Analysis of taxonomically related species did not generate the C. pseudotuberculosis mPCR amplification profile, thereby demonstrating the assay's specificity. As little as 1 pg of C. pseudotuberculosis genomic DNA was detected by this mPCR assay, demonstrating the sensitivity of the method. The detection limit in clinical samples was estimated to be 103 c.f.u. C. pseudotuberculosis could be detected directly in pus samples from infected sheep and goats (n=56) with a high diagnostic sensitivity (94.6 %). The developed assay significantly improves rapid C. pseudotuberculosis detection and could supersede bacteriological culture for microbiological and epidemiological diagnosis of CLA

Linear, Deterministic, and Order-Invariant Initialization Methods for the K-Means Clustering Algorithm

Over the past five decades, k-means has become the clustering algorithm of choice in many application domains primarily due to its simplicity, time/space efficiency, and invariance to the ordering of the data points. Unfortunately, the algorithm's sensitivity to the initial selection of the cluster centers remains to be its most serious drawback. Numerous initialization methods have been proposed to address this drawback. Many of these methods, however, have time complexity superlinear in the number of data points, which makes them impractical for large data sets. On the other hand, linear methods are often random and/or sensitive to the ordering of the data points. These methods are generally unreliable in that the quality of their results is unpredictable. Therefore, it is common practice to perform multiple runs of such methods and take the output of the run that produces the best results. Such a practice, however, greatly increases the computational requirements of the otherwise highly efficient k-means algorithm. In this chapter, we investigate the empirical performance of six linear, deterministic (non-random), and order-invariant k-means initialization methods on a large and diverse collection of data sets from the UCI Machine Learning Repository. The results demonstrate that two relatively unknown hierarchical initialization methods due to Su and Dy outperform the remaining four methods with respect to two objective effectiveness criteria. In addition, a recent method due to Erisoglu et al. performs surprisingly poorly.Comment: 21 pages, 2 figures, 5 tables, Partitional Clustering Algorithms (Springer, 2014). arXiv admin note: substantial text overlap with arXiv:1304.7465, arXiv:1209.196

Search for squarks and gluinos in events with isolated leptons, jets and missing transverse momentum at s√=8 TeV with the ATLAS detector

The results of a search for supersymmetry in final states containing at least one isolated lepton (electron or muon), jets and large missing transverse momentum with the ATLAS detector at the Large Hadron Collider are reported. The search is based on proton-proton collision data at a centre-of-mass energy s√=8 TeV collected in 2012, corresponding to an integrated luminosity of 20 fb−1. No significant excess above the Standard Model expectation is observed. Limits are set on supersymmetric particle masses for various supersymmetric models. Depending on the model, the search excludes gluino masses up to 1.32 TeV and squark masses up to 840 GeV. Limits are also set on the parameters of a minimal universal extra dimension model, excluding a compactification radius of 1/R c = 950 GeV for a cut-off scale times radius (ΛR c) of approximately 30

Measurement of the cross-section and charge asymmetry of WW bosons produced in proton-proton collisions at s=8\sqrt{s}=8 TeV with the ATLAS detector

This paper presents measurements of the $W^+ \rightarrow \mu^+\nu$ and $W^- \rightarrow \mu^-\nu$ cross-sections and the associated charge asymmetry as a function of the absolute pseudorapidity of the decay muon. The data were collected in proton--proton collisions at a centre-of-mass energy of 8 TeV with the ATLAS experiment at the LHC and correspond to a total integrated luminosity of 20.2~\mbox{fb^{-1}}. The precision of the cross-section measurements varies between 0.8% to 1.5% as a function of the pseudorapidity, excluding the 1.9% uncertainty on the integrated luminosity. The charge asymmetry is measured with an uncertainty between 0.002 and 0.003. The results are compared with predictions based on next-to-next-to-leading-order calculations with various parton distribution functions and have the sensitivity to discriminate between them.Comment: 38 pages in total, author list starting page 22, 5 figures, 4 tables, submitted to EPJC. All figures including auxiliary figures are available at https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/STDM-2017-13

Search for chargino-neutralino production with mass splittings near the electroweak scale in three-lepton final states in √s=13 TeV pp collisions with the ATLAS detector

A search for supersymmetry through the pair production of electroweakinos with mass splittings near the electroweak scale and decaying via on-shell W and Z bosons is presented for a three-lepton final state. The analyzed proton-proton collision data taken at a center-of-mass energy of √s=13  TeV were collected between 2015 and 2018 by the ATLAS experiment at the Large Hadron Collider, corresponding to an integrated luminosity of 139  fb−1. A search, emulating the recursive jigsaw reconstruction technique with easily reproducible laboratory-frame variables, is performed. The two excesses observed in the 2015–2016 data recursive jigsaw analysis in the low-mass three-lepton phase space are reproduced. Results with the full data set are in agreement with the Standard Model expectations. They are interpreted to set exclusion limits at the 95% confidence level on simplified models of chargino-neutralino pair production for masses up to 345 GeV