Guided resonances in photonic quasicrystals

In this paper, we report on the first evidence of guided resonances (GRs) in aperiodically-ordered photonic crystals, tied to the concept of "quasicrystals" in solid-state physics. Via a full-wave numerical study of the transmittance response and the modal structure of a photonic quasicrystal (PQC) slab based on a representative aperiodic geometry (Ammann-Beenker octagonal tiling), we demonstrate the possibility of exciting GR modes, and highlight similarities and differences with the periodic case. In particular, we show that, as for the periodic case, GRs arise from the coupling of the incident plane-wave with degenerate modes of the PQC slab that exhibit a matching symmetry in the spatial distribution, and can still be parameterized via a Fano-like model. Besides the phenomenological implications, our results may provide new degrees of freedom in the engineering of GRs, and pave the way for new developments and applications.Comment: 12 pages, 8 figures, 1 table. Three figures added; Sec. 3.3 significantly expande

Experimental evidence of guided resonances in photonic crystals with aperiodically-ordered supercells

We report on the first experimental evidence of guided resonances (GRs) in photonic crystal slabs based on aperiodically-ordered supercells. Using the Ammann-Beenker (quasiperiodic, 8-fold symmetric) tiling geometry, we present our study on the fabrication, experimental characterization, and full-wave numerical simulation of two representative structures (with different filling parameters) operating at near-infrared wavelengths (1300-1600 nm). Our results show a fairly good agreement between measurements and numerical predictions, and pave the way for the development of new strategies (based, e.g., on the lattice symmetry breaking) for GR engineering.Comment: 10 pages, 5 figures (minor revisions

Guided resonances in photonic crystals with point-defected aperiodically-ordered supercells

In this paper, we study the excitation of guided resonances (GRs) in photonic-crystal slabs based on point-defected aperiodically-ordered supercells. With specific reference to perforated-slab structures and the Ammann-Beenker octagonal lattice geometry, we carry out full-wave numerical studies of the plane-wave responses and of the underlying modal structures, which illustrate the representative effects induced by the introduction of symmetry-preserving and symmetry-breaking defects. Our results demonstrate that breaking the supercell mirror symmetries via the judicious introduction of point-defects enables for the excitation of otherwise uncoupled GRs, with control on the symmetry properties of their field distributions, thereby constituting an attractive alternative to those GR-engineering approaches based on the asymmetrization of the hole shape. In this framework, aperiodically-ordered supercells seem to be inherently suited, in view of the variety of inequivalent defect sites that they can offer.Comment: 13 pages, 12 figures, 1 table. Slight change in the title; major changes in the text and figure

SDS-PAGE: una herramienta útil en la evaluación preliminar de la actividad alexítera de extractos vegetales

El desarrollo de nuestro trabajo de investigación en la búsqueda de compuestos alexíteros de origen vegetal nos permite proponer la electroforesis en geles de poliacrilamida en condiciones desnaturalizantes, como método de screening rápido y confiable, para evaluar la actividad de extractos vegetales sobre proteínas del veneno de yarará, de manera de procesar mayor número de muestras vegetales y seleccionar aquellas que son activas. Para el desarrollo de la metodología, se utilizó un pool de veneno de Bothrops diporus desecado al vacío y extractos acuosos, alcohólicos y hexánicos de plantas autóctonas Aristolochia elegans, A. gibertii, Asclepia curassavica, Cissampelos pareira, Dorstenia brasiliensis, Eclipta prostrata, Iresine diffusa, Mikania micrantha, M. periplocifolia, M. coridifolia, Nectandra angustifolia, N. megapotamica, Sapium haematospermum y Trixis divaricata. Se realizaron pruebas in vitro (inhibición de la coagulación y hemólisis) para contrastar con los resultados obtenidos por SDS-PAGE. La correlación de los resultados obtenidos con técnicas in vitro validadas, permite sugerir el empleo de la técnica de SDS-PAGE como una herramienta útil en la evaluación preliminar de la actividad alexítera de extractos vegetales, propiedad evidenciada por la modificación en el perfil de bandas proteicas cuando se compara el veneno puro con el producto de la interacción extracto vegetal-veneno

Examen del contenido en ascaridol del aceite esencial de Chenopodium Ambrosioides L. (Paico)

Se ha examinado el contenido en ascaridol de varias muestras de Chenopodium ambrosioides L., colectadas en zonas del noroeste de Corrientes (Argentina) mediante CG. El uso popular de las infusiones de paico en el conurbano de Buenos Aires en afecciones intestinales, especialmente parasitosis, ha llevado a frecuentes intoxicaciones en niños y aún en adultos dado el estrecho margen entre la dosis terapéutica y la tóxica. Plantas recogidas en Corrientes muestran que su contenido en ascaridol no supera el 10 % del total de la esencia, a diferencia de especies de otras provincias de la Argentina, con lo cual disminuye el riesgo en el uso de esta planta en la zona

Application of Artificial Neural Network to Preoperative 18F-FDG PET/CT for Predicting Pathological Nodal Involvement in Non-small-cell Lung Cancer Patients

Purpose: To evaluate the performance of artificial neural networks (aNN) applied to preoperative 18F-FDG PET/CT for predicting nodal involvement in non-small-cell lung cancer (NSCLC) patients. Methods: We retrospectively analyzed data from 540 clinically resectable NSCLC patients (333 M; 67.4 \ub1 9 years) undergone preoperative 18F-FDG PET/CT and pulmonary resection with hilo-mediastinal lymphadenectomy. A 3-layers NN model was applied (dataset randomly splitted into 2/3 training and 1/3 testing). Using histopathological reference standard, NN performance for nodal involvement (N0/N+ patient) was calculated by ROC analysis in terms of: area under the curve (AUC), accuracy (ACC), sensitivity (SE), specificity (SP), positive and negative predictive values (PPV, NPV). Diagnostic performance of PET visual analysis (N+ patient: at least one node with uptake mediastinal blood-pool) and of logistic regression (LR) was evaluated. Results: Histology proved 108/540 (20%) nodal-metastatic patients. Among all collected data, relevant features selected as input parameters were: patients\u2019 age, tumor parameters (size, PET visual and semiquantitative features, histotype, grading), PET visual nodal result (patient-based, as N0/N+ and N0/N1/N2). Training and testing NN performance (AUC = 0.849, 0.769): ACC = 80 and 77%; SE = 72 and 58%; SP = 81 and 81%; PPV = 50 and 44%; NPV = 92 and 89%, respectively. Visual PET performance: ACC = 82%, SE = 32%, SP = 94%; PPV = 57%, NPV = 85%. Training and testing LR performance (AUC = 0.795, 0.763): ACC = 75 and 77%; SE = 68 and 55%; SP = 77 and 82%; PPV = 43 and 43%; NPV = 90 and 88%, respectively..Conclusions: aNN application to preoperative 18F-FDG PET/CT provides overall good performance for predicting nodal involvement in NSCLC patients candidate to surgery, especially for ruling out nodal metastases, being NPV the best diagnostic result; a high NPV was also reached by PET qualitative assessment. Moreover, in such population with low a priori nodal involvement probability, aNN better identify the relatively few and unexpected nodal-metastatic patients than PET analysis, so supporting the additional aNN use in case of PET-negative images

T-REX Operating Unit 3

OU3 is one of the six Operating Units of the Progetto Premiale T-REX. It is focused on the development of adaptive optics instrumentation for the European Extremely Large Telescope. The main activities of OU3 are the MAORY adaptive optics module, the MICADO infrared camera, the characterisation and forecast of atmospheric parameters for the E-ELT site and general developments for future adaptive optics systems. <P /

The MAORY first-light adaptive optics module for E-ELT

The MAORY adaptive optics module is part of the first light instrumentation suite for the E-ELT. The MAORY project phase B is going to start soon. This paper contains a system-level overview of the current instrument design

MAORY: adaptive optics module for the E-ELT

MAORY is one of the four instruments for the E-ELT approved for construction. It is an adaptive optics module offering two compensation modes: multi-conjugate and single-conjugate adaptive optics. The project has recently entered its phase B. A system-level overview of the current status of the project is given in this paper