Transmission properties of left-handed band-gap structures

We analyze transmission of electromagnetic waves through a periodic band-gap structure consisting of slabs of a left-handed metamaterial and air. Using the effective parameters of the metamaterial derived from its microscopic structure, we study, with the help of the transfer-matrix approach and by means of the finite-difference-time-domain numerical simulations, the transmission properties of such a left-handed photonic crystals in a novel type of band gap associated with the zero averaged refractive index. We demonstrate that the transmission can be made tunable by introducing defects, which allow to access selectively two different types of band gaps.Comment: 5 pages, 8 figure

Subwavelength imaging with opaque left-handed nonlinear lens

We introduce the concept of subwavelength imaging with an opaque nonlinear left-handed lens by generating the second-harmonic field. We consider a slab of composite left-handed metamaterial with quadratic nonlinear response and show that such a flat lens can form, under certain conditions, an image of the second-harmonic field of the source being opaque at the fundamental frequency.Comment: 3 pages, 3 figure

Birefringent left-handed metamaterials and perfect lenses

We describe the properties of birefringent left-handed metamaterials and introduce the concept of a birefringent perfect lens. We demonstrate that, in a sharp contrast to the conventional left-handed perfect lens at $\epsilon=\mu=-1$, where $\epsilon$ is the dielectric constant and $\mu$ is the magnetic permeability, the birefringent left-handed lens can focus either TE or TM polarized waves or both of them, allowing a spatial separation of the TE and TM images. We discuss several applications of the birefringent left-handed lenses such as the beam splitting and near-field diagnostics at the sub-wavelength scale.Comment: 4 pages 6 figure

Интернет-провайдеры как субъекты предупреждения сексуальной преступности в Интернете

The subject of the article is the provisions of the legislation of the Russian Federation aimed at ensuring the sexual inviolability of a minor.The object of the research is the relations connected with ensuring the sexual inviolability of minors.The Internet serves as an additional tool that facilitates access to minors, their social pages, the impact on the psyche of minors, and the involvement of children in destructive groups. However, not all articles establishing criminal liability for violation of the sexual inviolability of children contain a qualifying feature - this is the use of the Network in the implementation of such activities. Thus, Art. 135 of the Criminal Code of the Russian Federation, which establishes criminal liability for committing indecent acts against minors, does not contain a qualifying feature - the commission of a crime through the use of the Internet.The organization of Internet relations on the Web is carried out by various Internet providers, whose activities are connected both with organizing the communications of network users and with ensuring the circulation of information on the Internet. Based on these theses, the article provides answers to such questions as can acts were committed with the help of Internet technologies to be qualified under Art. 135 of the Criminal Code of the Russian Federation, is the use of Internet technologies by ISPs effective as a tool to combat crimes against the sexual integrity of minors carried out using the Web, and what legal and technical instruments will ensure the sexual integrity of children?The study showed that the norms of the Criminal Law aimed at preventing crimes related to the sexual inviolability of minors are also applicable to acts committed using the Internet. In accordance with the legislation of the Russian Federation, violence can take the form of physical or mental impact on a person, carried out through the Internet. Regarding the possibility of committing indecent acts on the Web, it can also be concluded that such acts can be recognized as depraved, despite the absence of direct physical contact with the body of the victim.States use various methods for determining the content, recognizing images distributed on the  Web.  The  most  commonly  used  technological  tool  is  the  information  monitoring method. However, the obligation to use this method, both in Russia and in European countries, is not provided for all types of hosting providers.In connection with the analysis of Russian legislation, we can conclude that the possibilities of such hosting providers as the owners of audiovisual services and news aggregators in the field of information monitoring remained unused. Thus, the Federal Law “On Information, Information Technologies and Information Protection” does not contain requirements for the owners of audiovisual services and news aggregators to conduct mandatory monitoring of information distributed on Internet platforms.The use of content filtering technology cannot be considered a panacea, but its mandatory use by various hosting providers will reduce the likelihood of distributing prohibited information.The requirement for the owners of social networks to monitor content by their users, defined by the Federal Law “On Information, Information Technologies, and Information Protection”, is only the first step taken towards reducing the volume of prohibited content posted on the Web. However, the requirements for the use of image and text recognition technologies by Internet providers remained outside.The article used the methods and techniques of formal logic - this is analysis and synthesis, analogy, comparison, hypothesis, proof in order to determine assumptions and find answers to the questions posed in the article.The study and comparative analysis of the practice of ensuring the safety of children from information posted on the Web, reflected in foreign studies, demonstrating possible solutions, made it possible to compare Russian experience with the experience of foreign colleagues and draw conclusions about approaches to solving the problems.The methods of forecasting and modeling are used for formulating possible ways to develop regulation and eliminate gaps in Russian legislation.Проводится анализ эффективности предотвращения преступлений в случае наделения интернет-посредников обязанностью использовать программные технологии модерации контента, распознавания образов и фильтрации. Актуальность исследования определяется ежегодным ростом статистических показателей преступлений против половой неприкосновенности и половой свободы несовершеннолетних

Achieving Algorithmic Transparency and Managing Risks of Data Security when Making Decisions without Human Interference: Legal Approaches

Objective: to compare modern approaches in law to the use of program codes and algorithms in decision-making that meet the principles of transparency and openness, as well as the increasingly stringent requirements for ensuring the security of personal and other big data obtained and processed algorithmically.Methods: the main methods for researching the principle of transparency in algorithmic decision-making were formal-legal and comparative analysis of legal acts and international standards of information security, as well as the principles and legal constructions contained in them.Results: it was determined that the development of information security standardization, inclusion in legal acts of requirements for the development of information technologies that comply with the principles of transparency and openness of applied algorithms will minimize the risks associated with the unlawful processing of users' big data and obtaining information about their privacy. Proposals were identified, related to the implementation of algorithmic transparency in the field of data processing legal regulation. Recommendations were formulated, based on which the legislator can solve the problem of ensuring the openness of the logic of information technology algorithms with regard to modern standards of information security.Scientific novelty: it consists in the substantiation of new trends and relevant legal approaches, which allow revealing the logic of data processing by digital and information technologies, based on the characterization of European standards of the “privacy by design” concept in new digital and information technologies of decision-making and data protection, as well as on the new legal requirements for artificial intelligence systems, including the requirement to ensure algorithmic transparency, and criteria for personal data and users' big data processing. This said, data protection is understood as a system of legal, technical and organizational principles aimed at ensuring personal data confidentiality.Practical significance: it is due to the need to study the best Russian and international practices in protecting the privacy of users of digital and information technologies, as well as the need for legislative provision of requirements for the use of algorithms that meet the principles of transparency and openness of personal data processing, taking into account the need to ensure confidentiality at all stages of the life cycle of their processing, which will ensure the continuity of security management

Second-harmonic generation in nonlinear left-handed metamaterials

We study the second-harmonic generation in left-handed metamaterials with a quadratic nonlinear response. We demonstrate a novel type of the exact phase matching between the backward propagating wave of the fundamental frequency and the forward propagating wave of the second harmonics. We show that this novel parametric process can convert a surface of the left-handed metamaterial into an effective mirror totally reflecting the second harmonics generated by an incident wave. We derive and analyze theoretically the coupled-mode equations for a semi-infinite nonlinear metamaterial. We also study numerically the second-harmonic generation by a metamaterial slab of a finite thickness, and reveal the existence of multistable nonlinear effects.Comment: 6 pages, 6 figure

Nonlinear magnetoinductive waves and domain walls in composite metamaterials

We describe novel physics of nonlinear magnetoinductive waves in left-handed composite metamaterials. We derive the coupled equations for describing the propagation of magnetoinductive waves, and show that in the nonlinear regime the magnetic response of a metamaterial may become bistable. We analyze modulational instability of different nonlinear states, and also demonstrate that nonlinear metamaterials may support the propagation of domain walls (kinks) connecting the regions with the positive and negative magnetization.Comment: 5 pages, 5 figure