Safety and security of programmable network infrastructures

Safety and security are two reliability properties of a system. A “safe” system provides protection against errors of trusted users, while a “secure” system protects against errors introduced by untrusted users. There is considerable overlap between mechanisms to support each property. Requirements for rapid service creation have stimulated the development of programmable network infrastructures, where end users or service providers can customize the properties of a network infrastructure while it continues to operate. A central concern of potential users of such systems is their reliability and, most specifically, their safety and security. In this article we explain the impact the network service model and architecture have on safety and security, and provide a model with which policies can be translated into restrictions of a general system. We illustrate these ideas with the Secure Active Network Environment (SANE) architecture, which provides a means of controlling access to the functions provided by any programmable infrastructure     

Random sequence multisets for synchronous code-divisionmultiple-access channels

The effect of using randomly selected sequence multisets for the uplink of a synchronous code-division multiple-access channel is considered. A tight lower bound on the expected value of the sum capacity over the ensemble of randomly selected sequence multisets is given. For large systems, the sum rate penalty for using randomly selected multisets is shown to be at most 1 nat and to vanish as the number of users becomes large, compared to the sequence length     

New Acceleration Principle of Charged Particles for Electronic Applications. The General Hierarchic Description

A new principle of acceleration of changed particles and quasineutral plasma beams is proposed and theoretically substantiated. The essence of this new acceleration principle is die utilization of EH-undulated fields, which resemble those of EH free-electron laser pumping systems. Here the charged particles are moving in a superposition of crossed magnetic and electric vortex undulated fields (EH-accelerator). The advantage of such systems is that both negative (electrons) and positive (ions) charged particles are accelerated simultaneously in the same longitudinal direction. In addition to the concept of the EH-accelerators, a new theoretical approach (the theory of hierarchic oscillations and waves) is given further development here. This approach has been used as a basis for the general nonlinear theory of the EH-accelerators and some other similar isochronous electronic devices with long-time interactions. In addition, several new calculation methods are presented, including the method for nonlinear current density calculations (called the averaged current-density equation hierarchic method) and two versions of hierarchic asymptotic algorithms for the integration of Maxwell's equations.     

Should Russia increase domestic prices for natural gas?

Previous analyses of Russia's dual pricing system and hidden subsidies for natural gas, have neglected to assess the dual pricing system as a domestic environmental policy. If dual pricing is considered as a policy to reduce conventional air pollutants, it is more than economically justified in Russia on the basis of avoided health risks. In the short term, the substitution of coal for natural gas may result in significant additional human health risk, which translates into economic damage. An alternative abatement possibility is expensive and unlikely enforceable, due to weak environmental regulation. The authors conclude that while the price differential can be expected to diminish over time, as Russia increasingly moves to a market economy, in the near-term, dual pricing of natural gas remains the most efficient environmental policy for Russia.     

Gerfried Zeichen — Aus Anlass seiner Emeritierung

Ohne Zusammenfassung     

On Chiroptical Spectroscopy of Turbid Media with Optically Soft, Large Spherical Particles

The influence of the size of particles on the circular dichroism and optical rotatory dispersion spectra of turbid layers with globules of chiral substances is studied. Simple equations for large chiral particles with the refractive index close to the refractive index of the surrounding medium are obtained and analyzed. Formulae derived can be used for the solution of the inverse problem, namely for obtaining intrinsic spectra of substances inside small particles from measurements of spectra for turbid layers.     

Bioinspired Magnetite Crystallization Directed by Random Copolypeptides

Control over magnetite (Fe₃O₄) formation is difficult to achieve in synthetic systems without using non‐aqueous media and high temperatures. In contrast, Nature employs often intrinsically disordered proteins to tightly tailor the size, shape, purity, and organization of the nanocrystals to optimize their magnetic properties. Inspired by such “flexible polyelectrolytes,” here random copolypeptides having different amino acid compositions are used as control agents in the bioinspired coprecipitation of magnetite through a ferrihydrite precursor, following a recently developed mineralization protocol. Importantly, the copolypeptide library is designed such that the amino acid composition can be optimized to simultaneously direct the size of the nanoparticles as well as their dispersibility in aqueous media in a one‐pot manner. Acidic amino acids are demonstrated to regulate the crystal size by delaying nucleation and reducing growth. Their relative content thus can be balanced to tune between the superparamagnetic and ferrimagnetic regimes, and high contents of negatively charged amino acids result in colloidal stabilization of superparamagnetic nanoparticles at high pH. Conversely, with positively charged lysine‐rich copolypeptides ferrimagnetic crystals are obtained which are stabilized at neutral pH and self‐organize in chains, as visualized by cryo‐transmission electron microscopy. Altogether, the presented findings give important insights for the future development of additive‐mediated nanomaterial syntheses.     

Engineering Gold Nanotubes with Controlled Length and Near‐Infrared Absorption for Theranostic Applications

Important aspects in engineering gold nanoparticles for theranostic applications include the control of size, optical properties, cytotoxicity, biodistribution, and clearance. In this study, gold nanotubes with controlled length and tunable absorption in the near‐infrared (NIR) region have been exploited for applications as photothermal conversion agents and in vivo photoacoustic imaging contrast agents. A length‐controlled synthesis has been developed to fabricate gold nanotubes (NTs) with well‐defined shape (i.e., inner void and open ends), high crystallinity, and tunable NIR surface plasmon resonance. A coating of poly(sodium 4‐styrenesulfonate) (PSS) endows the nanotubes with colloidal stability and low cytotoxicity. The PSS‐coated Au NTs have the following characteristics: i) cellular uptake by colorectal cancer cells and macrophage cells, ii) photothermal ablation of cancer cells using single wavelength pulse laser irradiation, iii) excellent in vivo photoacoustic signal generation capability and accumulation at the tumor site, iv) hepatobiliary clearance within 72 h postintravenous injection. These results demonstrate that these PSS‐coated Au NTs have the ideal attributes to develop their potential as effective and safe in vivo imaging nanoprobes, photothermal conversion agents, and drug delivery vehicles. To the best of knowledge, this is the first in vitro and in vivo study of gold nanotubes.