Surface Plasmon Dispersion Relations in Chains of Metallic Nanoparticles: Exact Quasistatic Calculation

We calculate the surface plasmon dispersion relations for a periodic chain of spherical metallic nanoparticles in an isotropic host, including all multipole modes in a generalized tight-binding approach. For sufficiently small particles ($kd \ll 1$, where $k$ is the wave vector and $d$ is the interparticle separation), the calculation is exact. The lowest bands differ only slightly from previous point-dipole calculations provided the particle radius $a \lesssim d/3$, but differ substantially at smaller separation. We also calculate the dispersion relations for many higher bands, and estimate the group velocity $v_g$ and the exponential decay length $\xi_D$ for energy propagation for the lowest two bands due to single-grain damping. For $a/d=0.33$, the result for $\xi_D$ is in qualitative agreement with experiments on gold nanoparticle chains, while for larger $a/d$, such as $a/d=0.45$, $v_g$ and $\xi_D$ are expected to be strongly $k$-dependent because of the multipole corrections. When $a/d \sim 1/2$, we predict novel percolation effects in the spectrum, and find surprising symmetry in the plasmon band structure. Finally, we reformulate the band structure equations for a Drude metal in the time domain, and suggest how to include localized driving electric fields in the equations of motion.Comment: 19 pages 3 figures To be published in Phy. Rev.

Picturing Paul against empire: the Gospel of the apostle to the gentiles in imperial perspective

Presented at Vancouver School of Theology, 14 N 2005

Magnetization transfer effect on T1 relaxometry on 1.5T vs. 3T

PURPOSE: To assess the variability of incidental magnetization transfer effect (MT) by the number of slices and the magnetic field strength. METHODS: Various magnetic resonance images (MRI) were obtained with a phantom containing a series of solutions of gadolinium (Gd) and sucrose in distilled water, agarose gel and two vials with olive oil and distilled water. A diffusion weighted image (DWI) sequence was acquired to determine diffusion coefficient for each component of the phantom. Several inversion recovery (IR) sequences having different TI values were run for single-slice and used to calculate T1 relaxation time with maximum precision and minimizing magnetization transfer effect. The T1 relaxation value resulting from processing IR sequences was used as reference value. The mixed-TSE sequences were used to calculate T1, T2 and PD values and to assess MT effect for single-slice as for multi-slice acquisition. All the DICOM MR images were processed using various algorithms programmed in Mathcad (version 2001i, PTC Needham, MA) by Dr. Hernan Jara. According with the potential of each sequences the programs generated the qMRI maps and values of T1, T2, PD were obtained for all the components of the phantom. Values resulted from Mathcad calculation were used for analysis. All the acquisitions, calculations and measurements were performed for 1.5T and 3T field strength

Old Worlds, New Travels: Jack London’s People of the Abyss, Ernest Hemingway’s The Sun Also Rises, and the Cultural Politics of Travel

Ye

Picturing words: The semantics of speech balloons

Semantics traditionally focuses on linguistic meaning. In recent years, the Super Linguistics movement has tried to broaden the scope of inquiry in various directions, including an extension of semantics to talk about the meaning of pictures. There are close similarities between the interpretation of language and of pictures. Most fundamentally, pictures, like utterances, can be either true or false of a given state of affairs, and hence both express propositions (Zimmermann, 2016; Greenberg, 2013; Abusch, 2015). Moreover, sequences of pictures, like sequences of utterances, can be used to tell stories. Wordless picture books, comics, and film are cases in point. In this paper I pick up the project of providing a dynamic semantic account of pictorial story-telling, started by Abusch (2012) and continued by Abusch & Rooth (2017); Maier & Bimpikou (2019); Fernando (2020). More specifically, I propose here a semantics of speech and thought bubbles by adding event reference to PicDRT. To get there I first review the projection-based semantics for pictures (section 1), noting the fundamental distinction between symbolic and iconic meaning that makes speech bubbles especially interesting (section 2). I then review the dynamic PicDRT framework for pictorial narratives (section 3), add events (section 4), and propose an account of speech bubbles as quotational event modification (section 5). I end with a brief look at other conventional, symbolic enrichments in comics (section 6)

Search for H→bbˉ\text{H}\to \text{b}\bar{\text{b}} in association with single top quarks as a test of Higgs couplings

The associated production of Higgs boson and single top quark is of particular interest since it is senstive to the relative sign of the Higgs boson coupling to gauge bosons and the Yukawa coupling $y$ to fermions. The presented analysis is setting upper production limits on a model with $y_\text{t}=-1$, which has an enhanced cross section compared to the standard model expectation. For this it focusses on the Higgs boson decaying to a pair of b quarks and uses the full dataset of $pp$ collisions recorded with the CMS detector in 2012. It reports an upper limit on 7.57 times the expected cross section, with an expected sensitivity of 5.14. This translates into the exclusion of associated tHq production with $y_\text{t}=-1$-like characteristics with a cross section smaller than 1.77\,pb

Product Differentiation or Spatial Monopoly? The Market Areas of Austrian Universities in Business Education.

Series: SRE - Discussion Paper