Terahertz active spatial filtering through optically tunable hyperbolic metamaterials

We theoretically consider infrared-driven hyperbolic metamaterials able to spatially filtering terahertz radiation. The metamaterial is a slab made of alternating semiconductor and dielectric layers whose homogenized uniaxial response, at terahertz frequencies, shows principal permittivities of different signs. The gap provided by metamaterial hyperbolic dispersion allows the slab to stop spatial frequencies within a bandwidth tunable by changing the infrared radiation intensity. We numerically prove the device functionality by resorting to full wave simulation coupled to the dynamics of charge carries photoexcited by infrared radiation in semiconductor layers.Comment: 3 pages, 4 figures. Submitted for publication on Applied Physics Letter

Anti-pittorialismo sublime e ragione etica: la dialettica del gusto nella Inquiry di Edmund Burke

In A Philosophical Inquiry into the Origin of our Ideas of the Sublime and Beautiful (1757) il gusto ha un campo di pertinenza ampio. La definizione del bello e del sublime e le loro manifestazione nella letteratura e nelle arti figurative costituiscono il nucleo delle riflessioni estetiche intorno alle quali Edmund Burke articola la sua teoria del linguaggio incentrata su un gusto anti-pittorialista. Nel saggio introduttivo che aggiunse alla seconda edizione, pubblicata nel 1759, egli sviluppa un discorso intorno all’etica del gusto per mostrare come l’apprezzamento dell’arte abbia profonde diramazioni nella sfera sociale. Rielaborando le concezioni empiriste riguardo alle facoltà cognitive e critiche, Burke si prefigge non solo di identificare le passioni suscitate dalla fruizione artistica e di indagare le specifiche modalità espressive attribuibili al codice verbale e visivo, ma anche di comprendere quali siano i tratti comuni o individuali, innati o acquisibili, essenziali o variabili nei criteri di giudizio e di apprezzamento. La riflessione burkeana sul gusto mostra la coesistenza di speculazioni estetiche e obiettivi etici, che genera una dialettica irresolubile e al contempo vitalizzante. Appropriandosi delle teorie empiriste, rivisitando il topos dell’ut pictura poësis, Burke si muove con decisione verso l’anti-pittorialismo e approda al sublime, misterioso e finanche sconvolgente. Tuttavia, le riflessioni sul gusto espresse nel saggio incluso nella seconda edizione del 1759 rivestono le questioni estetiche di valenze etiche, tentando di riportare l’asse del discorso entro la sfera razionale. L’oscurità trasporta, sommuove e può celare aspetti meravigliosi e terribili; l’intelletto discerne, chiarifica e fissa le idee. Desiderio e disciplina: l’Inquiry porta con sé, dialetticamente, l’esercizio della ragione e lo slancio della visione

Dante, Dante Gabriel Rossetti, and Their Verbal/Visual Personae

Dante Gabriel Rossetti’s Dante Alighieri. The New Life (La Vita Nuova), published in The Early Italian Poets from Ciullo D’Alcamo to Dante Alighieri (1100-1200-1300) (1847-48, published 1861) and the innumerable sketches, drawings, and paintings he dedicated to Dante generate connections between two different epochs and cultural areas. Puzzling and enlightening, they are verbal and visual transpositions as well as original works of art that invite an enquiry into Rossetti’s interart, transcultural, and self-reflexive appropriation and re-shaping of Dante’s poetics and aesthetics.Dante Gabriel Rossetti’s Dante Alighieri. The New Life (La Vita Nuova), published in The Early Italian Poets from Ciullo D’Alcamo to Dante Alighieri (1100-1200-1300) (1847-48, published 1861) and the innumerable sketches, drawings, and paintings he dedicated to Dante generate connections between two different epochs and cultural areas. Puzzling and enlightening, they are verbal and visual transpositions as well as original works of art that invite an enquiry into Rossetti’s interart, transcultural, and self-reflexive appropriation and re-shaping of Dante’s poetics and aesthetics

Greening the Genre. Fairy Tale, the Apocalypse, and Ecology Documentaries

New perspectives are required to investigate forms of creative and critical writing that produce ecological knowledge and representation, to identify stylistic and structural features that strengthen or undermine environmental communication, and to appreciate narrative modes that may inspire a change in cultural mindsets and behaviours. The relationships between modes of communication and intergenerational dynamics are essential to understanding the power of environmental news and stories. Fairy tales and fables, in which the joy of the happy ending still resonates with doubts and fears, and dystopian and apocalyptic stories, in which destruction can raise palingenetic hope, are essential to environmental communication. David Attenborough’s ecology documentaries form a new green genre that blends the fairy tale and apocalyptic dystopia and uses entertainment to produce public understanding of the ecological crisis. Who is the narrator and how is the narrative built and delivered to develop environmental advocacy? Can nature documentary TV series contribute to changing consumers’ habits? Is the role played by celebrity conservationists and conservationist celebrities essential to promoting a cultural shift? These are intriguing questions raised by ecological narratives

Dante, Dante Gabriel Rossetti, and Their Verbal/Visual Personae

Dante Gabriel Rossetti’s Dante Alighieri. The New Life (La Vita Nuova), published in The Early Italian Poets from Ciullo D’Alcamo to Dante Alighieri (1100-1200-1300) (1847-48, published 1861) and the innumerable sketches, drawings, and paintings he dedicated to Dante generate connections between two different epochs and cultural areas. Puzzling and enlightening, they are verbal and visual transpositions as well as original works of art that invite an enquiry into Rossetti’s interart, transcultural, and self-reflexive appropriation and re-shaping of Dante’s poetics and aesthetics

Interaction of proteins in solution from small angle scattering: a perturbative approach

In this work, an improved methodology for studying interactions of proteins in solution by small-angle scattering, is presented. Unlike the most common approach, where the protein-protein correlation functions $g_{ij}(r)$ are approximated by their zero-density limit (i.e. the Boltzmann factor), we propose a more accurate representation of $g_{ij}(r)$ which takes into account terms up to the first order in the density expansion of the mean-force potential. This improvement is expected to be particulary effective in the case of strong protein-protein interactions at intermediate concentrations. The method is applied to analyse small angle X-ray scattering data obtained as a function of the ionic strength (from 7 to 507 mM) from acidic solutions of $\beta$-Lactoglobuline at the fixed concentration of 10 $\rm g L^{-1}$. The results are compared with those obtained using the zero-density approximation and show a significant improvement particularly in the more demanding case of low ionic strength.Comment: 12 pages, 3 figures, to appear in Biophysical Journal (April 2002) Due to an unfortunate name mismatch, the original submission contained an incorrect sourc