Dielectric Metamaterials with Toroidal Dipolar Response

Toroidal multipoles are the terms missing in the standard multipole expansion; they are usually overlooked due to their relatively weak coupling to the electromagnetic fields. Here we propose and theoretically study all-dielectric metamaterials of a special class that represent a simple electromagnetic system supporting toroidal dipolar excitations in the THz part of the spectrum. We show that resonant transmission and reflection of such metamaterials is dominated by toroidal dipole scattering, the neglect of which would result in a misunderstanding interpretation of the metamaterials macroscopic response. Due to the unique field configuration of the toroidal mode the proposed metamaterials could serve as a platform for sensing, or enhancement of light absorption and optical nonlinearities

Physical Complexity of Symbolic Sequences

A practical measure for the complexity of sequences of symbols (``strings'') is introduced that is rooted in automata theory but avoids the problems of Kolmogorov-Chaitin complexity. This physical complexity can be estimated for ensembles of sequences, for which it reverts to the difference between the maximal entropy of the ensemble and the actual entropy given the specific environment within which the sequence is to be interpreted. Thus, the physical complexity measures the amount of information about the environment that is coded in the sequence, and is conditional on such an environment. In practice, an estimate of the complexity of a string can be obtained by counting the number of loci per string that are fixed in the ensemble, while the volatile positions represent, again with respect to the environment, randomness. We apply this measure to tRNA sequence data.Comment: 12 pages LaTeX2e, 3 postscript figures, uses elsart.cls. Substantially improved and clarified version, includes application to EMBL tRNA sequence dat

The use of information theory in evolutionary biology

Information is a key concept in evolutionary biology. Information is stored in biological organism's genomes, and used to generate the organism as well as to maintain and control it. Information is also "that which evolves". When a population adapts to a local environment, information about this environment is fixed in a representative genome. However, when an environment changes, information can be lost. At the same time, information is processed by animal brains to survive in complex environments, and the capacity for information processing also evolves. Here I review applications of information theory to the evolution of proteins as well as to the evolution of information processing in simulated agents that adapt to perform a complex task.Comment: 25 pages, 7 figures. To appear in "The Year in Evolutionary Biology", of the Annals of the NY Academy of Science

All-dielectric nanoantenna for efficient reflectors irradiation

In this paper, we propose a new kind of nanoantenna for effective illumination of parabolic surfaces, constituting of a silicon cylinder acting as a reflector and dipole source as an emitter. Tailored parameters of the nanoantenna ensure specific radiation pattern with broad main lobe and strongly suppressed side lobes that in the E-plane of the dipole is quite similar to the ideal “П” configuration, necessary for an as uniform as possible illumination of parabolic surfaces. This above radiation pattern is mostly due to the properly designed dielectric inclusion in the reflector that, therefore, is free of any losses. Consequently, we study how varying the antenna parameters affects the radiation pattern.Results of our numerical simulations are compared with already existing ones and highlight the principal features that provide the desired effect. Furthermore, due to the simple geometry of the inclusions, the considered nanoantenna, required in application such as nanoreflector antennas and/or nanophotonic devices, exhibits advantages in manufacturing processes with respect to already proposed solutions

"Сакральные войны" в рамках мусульманской демонологии

Pavel Basharin's article touches on changing demonology of Muslim Iran as it concerns beliefs on the wars that happen between supernatural creatures. Such wars are mentioned so in Arabic as in Persian literature. Their general principles concerning battles of jinns and ghuls against diws, peris against fravashis and jinns can be reconstructed on the ground of a number of literary stories about the wars between supernatural creatures from Iranian (Sogdian text about Rustam, Shah-nama) and Arabian epic stories to fairy tales from the 1001 Nights. These wars represented struggle of two eternal principles of Good and Evil. Their fighters, who pursuit the same high aims, personify a cosmic principle of the world in the battle with their enemy. The author stresses a basic difference dividing Arabian and Persian folk tradition in the matter. While the latter insists on social hierarchy in both human and supernatural world, the former does not believe supernatural creatures including ghuls, jinns, shaytans a kind of social beings. В статье Павла Башарина рассматривается эволюция демонологии мусульманского Ирана в поверьях, связанных с войнами между сверхъестественными существами. Такие войны упоминаются как в арабской, так и в персидской литературе. Их основные принципы, связанные с битвами между джиннами и гулями против дивов, пери против фраваши и джиннов, могут быть реконструированы на основе литературных сюжетов о войнах между сверхъестественными существами, от иранских (согдийский текст о Рустаме, Шах-нама) и арабских эпических произведений и до сказок 1001 ночи. В этих войнах отражена борьба между двумя извечными началами – Добром и Злом. Люди, участвующие в них, преследуют те же высокие цели, аккумулируя в себе космический принцип функционирования мира. Автор подчёркивает принципиальное различие между арабской и персидской фольклорной традицией описания сакральных войн. В то время как последняя подчёркивает наличие социальной иерархии и в человеческом мире, и в мире сверхъестественного, первая не признаёт гулей, джиннов, шайтанов и прочих сверхъестественных созданий социальными существами.