Tardos fingerprinting is better than we thought

We review the fingerprinting scheme by Tardos and show that it has a much better performance than suggested by the proofs in Tardos' original paper. In particular, the length of the codewords can be significantly reduced. First we generalize the proofs of the false positive and false negative error probabilities with the following modifications: (1) we replace Tardos' hard-coded numbers by variables and (2) we allow for independently chosen false positive and false negative error rates. It turns out that all the collusion-resistance properties can still be proven when the code length is reduced by a factor of more than 2. Second, we study the statistical properties of the fingerprinting scheme, in particular the average and variance of the accusations. We identify which colluder strategy forces the content owner to employ the longest code. Using a gaussian approximation for the probability density functions of the accusations, we show that the required false negative and false positive error rate can be achieved with codes that are a factor 2 shorter than required for rigid proofs. Combining the results of these two approaches, we show that the Tardos scheme can be used with a code length approximately 5 times shorter than in the original construction.Comment: Modified presentation of result

Ballistic spin transport in exciton gases

Traditional spintronics relies on spin transport by charge carriers, such as electrons in semiconductor crystals. This brings several complications: the Pauli principle prevents the carriers from moving with the same speed; Coulomb repulsion leads to rapid dephasing of electron flows. Spin-optronics is a valuable alternative to traditional spintronics. In spin-optronic devices the spin currents are carried by electrically neutral bosonic quasi-particles: excitons or exciton-polaritons. They can form highly coherent quantum liquids and carry spins over macroscopic distances. The price to pay is a finite life-time of the bosonic spin carriers. We present the theory of exciton ballistic spin transport which may be applied to a range of systems where bosonic spin transport has been reported, in particular, to indirect excitons in coupled GaAs/AlGaAs quantum wells. We describe the effect of spin-orbit interaction of electrons and holes on the exciton spin, account for the Zeeman effect induced by external magnetic fields, long range and short range exchange splittings of the exciton resonances. We also consider exciton transport in the non-linear regime and discuss the definitions of exciton spin current, polarization current and spin conductivity.Comment: 16 pages, 10 figures to be published in Phys. Rev.

Real-time agent middleware experiments on java-based processors towards distributed satellite systems

Distributed satellite systems are large research topics, spanning many fields such as communications, networking schemes, high performance computing, and distributed operations. DARPA's F6 fractionated spacecraft mission is a prime example, culminating in the launch of technology demonstration satellites for autonomous and rapidly configurable satellite architectures. Recent developments at Surrey Space Centre have included the development of a Java enabled system-on-a-chip solution towards running homogenous agents and middleware software configurations

General practitioner management for chronic sensorineural hearing loss in older adults

Introduction. The article is devoted to the special role of the primary care physician - therapist, geriatrician, general practitioner, in assisting the elderly and senile in taking appropriate and timely measures in identifying people with chronic sensorineural hearing loss (SNL), consulting them at the stage of primary health care.Aim of the study. Understand the intended role of general practitioners and therapist in identifying and counseling patients with hearing loss in primary health care.Materials and methods. A survey of general practitioners and therapist was conducted in the form of 88 statements, collected in six concepts, in response to the question “What should be the role of a general practitioner in the treatment of chronic sensorineural hearing loss in persons of an older age group?” in the format of a Google-questionnaire.Results. The results showed a sufficient awareness of general practitioners and therapist about the predisposition of their elderly patients to hearing loss and the significance of the associated consequences on the quality of life. As a result of the data obtained, the highest percentage of statements was noted in Concept 1 “Determine - Diagnose - Discuss” and varied on individual issues from 27.8% to 55.6%, the lowest - in Concept 5 “Educate - Strategise - Encourage” and ranged from 16.7% to 44.4%.Discussion. Strengthening collaboration between therapists and otorhinolaryngologists, otorhinolaryngologists, and audiologists is the most effective strategy for reducing individuals with untreated SNL. The importance of the role of the primary care physician in multidisciplinary care and its coordination is especially emphasized in the concept of “Know - Refer - Coordinate”.Conclusions. The authors conclude that the priority concept of modern health care, which makes it possible to significantly improve the quality of life of patients in the older age group and reduce the psychosocial consequences of hearing loss

Spin Texture in a Cold Exciton Gas

We report on the observation of a spin texture in a cold exciton gas in a GaAs/AlGaAs coupled quantum well structure. The spin texture is observed around the exciton rings. The observed phenomena include: a ring of linear polarization, a vortex of linear polarization with polarization perpendicular to the radial direction, an anisotropy in the exciton flux, a skew of the exciton fluxes in orthogonal circular polarizations and a corresponding four-leaf pattern of circular polarization, a periodic spin texture, and extended exciton coherence in the region of the polarization vortex. The data indicate a transport regime where the spin polarization is locked to the direction of particle propagation and scattering is suppressed.Comment: version 2 contains updated supplementary materia

A New High-Level Reconfigurable Lossless Image Compression System for Space Applications

On board image data compression is an important feature of satellite remote sensing payloads. Reconfigurable Intellectual Property (IP) cores can enable change of functionality or modifications. A new and efficient lossless image compression scheme for space applications is proposed. In this paper, we present a lossless image compression IP core designed using AccelDSP, which gives users high level of flexibility. One typical configuration is implemented and tested on an FPGA prototyping board. Finally, it is integrated successfully into a System-on-Chip platform for payload data processing and control