Evaluating Receiver Noise Temperature of a Radio Telescope in the Presence of Mutual Coupling: Comparison of Current Methodologies

© 2019 European Association on Antennas and Propagation. We present the computation of receiver noise temperature which includes the effects of mutual coupling of two different radio telescopes deployed in the Murchison Radio-astronomy Observatory, namely the Murchison Widefield Array and the prototype Engineering Development Array. We used three different formulations that only require information of measured noise parameters of the low noise amplifier as used in the radio telescope and simulated S-parameter of the array to perform the calculation. In addition, we show convergence in computed receiver noise temperature for various pointing angles and array configurations (uniform and pseudo-random) that indicate agreement with existing literature

Evaluating Molecular Cobalt Complexes for the Conversion of N_2 to NH_3

We report a molecular Co−N_2 complex that generates a greater-than-stoichiometric yield of NH_3 (>200% NH_3 per Co−N_2 precursor) via the direct reduction of N_2 with protons and electrons. A comparison of the featured Co−N_2 complex with structurally related Co−N_2 and Fe−N_2 species shows how remarkably sensitive the N_2 reduction performance of potential precatalysts is. As discussed, structural and electronic effects are relevant to Co/Fe−N_2 conversion activity, including π basicity, charge state, and geometric flexibility

Pan-cancer systematic identification of lncRNAs associated with cancer prognosis

Background The “dark matter” of the genome harbors several non-coding RNA species including Long non-coding RNAs (lncRNAs), which have been implicated in neoplasia but remain understudied. RNA-seq has provided deep insights into the nature of lncRNAs in cancer but current RNA-seq data are rarely accompanied by longitudinal patient survival information. In contrast, a plethora of microarray studies have collected these clinical metadata that can be leveraged to identify novel associations between gene expression and clinical phenotypes. Methods In this study, we developed an analysis framework that computationally integrates RNA-seq and microarray data to systematically screen 9,463 lncRNAs for association with mortality risk across 20 cancer types. Results In total, we identified a comprehensive list of associations between lncRNAs and patient survival and demonstrate that these prognostic lncRNAs are under selective pressure and may be functional. Our results provide valuable insights that facilitate further exploration of lncRNAs and their potential as cancer biomarkers and drug targets

Electromagnetic modelling of the SKA-LOW AAVS1.5 prototype

The numerical modelling of the Square Kilometre Array (SKA) Aperture Array Verification System Version 1.5 is discussed. The role of this SKA prototype is placed within the perspective of the overall SKA project. The dual-polarized log-periodic SKALA4.1 antenna elements comprising a station are briefly described, along with some considerations regarding the station. Computational simulation aspects are considered, and preliminary results shown. An appraisal of the implications for station-level calibration concludes the paper

Electromagnetic modelling of the SKA-LOW AAVS2 prototype

The computational electromagnetic modelling of a large radio telescope prototype array for the Square Kilometer Array is described. The numerical models, using the Method of Moments, are characterised by a very large number of unknowns, requiring the use of fast solution methods and high performance computing platforms. Good agreement has been obtained between results obtained on two different commercial codes. Results for both embedded element patterns and the station beam are shown. The use of the computed embedded element patterns for array calibration is briefly addressed

Shaping gold nanocomposites with tunable optical properties

We report the synthesis of morphological uniform composites using miniemulsions of poly(tert-butyl acrylate) or poly(styrene) containing organically capped gold nanocrystals (NCs). The optical features of such hybrid structures are dominated by plasmonic effects and depend critically on the morphology of the resulting nanocomposite. In particular, we demonstrate the ability to tune the overall optical response in the visible spectral region by varying the Au NCs arrangement within the polymer matrix, and therefore the interparticle plasmon coupling, using Au NCs resulting from the same batch of synthesis. This is a consequence of two well-known effects on the optical properties of Au particles: the variation of the surrounding dielectric refractive index and interparticle plasmonic coupling. The research reported here shows a general strategy to produce optical responsive nanocomposites via control of the morphology of submicrometric polymer particles containing metal nanocrystals and thus is an alternative to the more common strategy of size tuning metal nanoparticles used as nanofillers