New directions in EEG measurement: an investigation into the fidelity of electrical potential sensor signals

Low frequency noise performance is the key indicator in determining the signal to noise ratio of a capacitively coupled sensor when used to acquire electroencephalogram signals. For this reason, a prototype Electric Potential Sensor device based on an auto-zero operational amplifier has been developed and evaluated. The absence of 1/f noise in these devices makes them ideal for use with signal frequencies ~10 Hz or less. The active electrodes are designed to be physically and electrically robust and chemically and biochemically inert. They are electrically insulated (anodized) and have diameters of 12 mm or 18 mm. In both cases, the sensors are housed in inert stainless steel machined housings with the electronics fabricated in surface mount components on a printed circuit board compatible with epoxy potting compounds. Potted sensors are designed to be immersed in alcohol for sterilization purposes. A comparative study was conducted with a commercial wet gel electrode system. These studies comprised measurements of both free running electroencephalogram and Event Related Potentials. Quality of the recorded electroencephalogram was assessed using three methods of inspection of raw signal, comparing signal to noise ratios, and Event Related Potentials noise analysis. A strictly comparable signal to noise ratio was observed and the overall conclusion from these comparative studies is that the noise performance of the new sensor is appropriate

Impact of DM direct searches and the LHC analyses on branon phenomenology

Dark Matter direct detection experiments are able to exclude interesting parameter space regions of particle models which predict an important amount of thermal relics. We use recent data to constrain the branon model and to compute the region that is favored by CDMS measurements. Within this work, we also update present colliders constraints with new studies coming from the LHC. Despite the present low luminosity, it is remarkable that for heavy branons, CMS and ATLAS measurements are already more constraining than previous analyses performed with TEVATRON and LEP data.Comment: 17 pages, 2 figure

On a problem of A. Weil

A topological invariant of the geodesic laminations on a modular surface is constructed. The invariant has a continuous part (the tail of a continued fraction) and a combinatorial part (the singularity data). It is shown, that the invariant is complete, i.e. the geodesic lamination can be recovered from the invariant. The continuous part of the invariant has geometric meaning of a slope of lamination on the surface.Comment: to appear Beitr\"age zur Algebra und Geometri

Using the atmospheric CO2 growth rate to constrain the CO2 flux from land use and land cover change since 1900

We explore the ability of the atmospheric CO2 record since 1900 to constrain the source of CO2 from land use and land cover change (hereafter “land use”), taking account of uncertainties in other terms in the global carbon budget. We find that the atmospheric constraint favors land use CO2 flux estimates with lower decadal variability and can identify potentially erroneous features, such as emission peaks around 1960 and after 2000, in some published estimates. Furthermore, we resolve an offset in the global carbon budget that is most plausibly attributed to the land use flux. This correction shifts the mean land use flux since 1900 across 20 published estimates down by 0.35 PgC year−1 to 1.04 ± 0.57 PgC year−1, which is within the range but at the low end of these estimates. We show that the atmospheric CO2 record can provide insights into the time history of the land use flux that may reduce uncertainty in this term and improve current understanding and projections of the global carbon cycle. © 2022 The Authors. Global Change Biology published by John Wiley Sons Ltd

Ergodic Jacobi matrices and conformal maps

We study structural properties of the Lyapunov exponent $\gamma$ and the density of states $k$ for ergodic (or just invariant) Jacobi matrices in a general framework. In this analysis, a central role is played by the function $w=-\gamma+i\pi k$ as a conformal map between certain domains. This idea goes back to Marchenko and Ostrovskii, who used this device in their analysis of the periodic problem

Weak Liouville-Arnold Theorems & Their Implications

This paper studies the existence of invariant smooth Lagrangian graphs for Tonelli Hamiltonian systems with symmetries. In particular, we consider Tonelli Hamiltonians with n independent but not necessarily involutive constants of motion and obtain two theorems reminiscent of the Liouville-Arnold theorem. Moreover, we also obtain results on the structure of the configuration spaces of such systems that are reminiscent of results on the configuration space of completely integrable Tonelli Hamiltonians.Comment: 24 pages, 1 figure; v2 corrects typo in online abstract; v3 includes new title (was: A Weak Liouville-Arnold Theorem), re-arrangement of introduction, re-numbering of main theorems; v4 updates the authors' email and physical addresses, clarifies notation in section 4. Final versio

An Extended Grid of Nova Models: II. The Parameter Space of Nova Outbursts

This paper is a sequel to an earlier paper devoted to multiple, multicycle nova evolution models (Prialnik & Kovetz 1995, first paper of the series), which showed that the different characteristics of nova outbursts can be reproduced by varying the values of three basic and independent parameters: the white dwarf mass-M_{WD}, the temperature of its isothermal core-T_{WD} and the mass transfer rate-Mdot. Apart from being the largest computational classical novae parameter-space survey, we show here that the parameter space is constrained by several analytical considerations and find its limiting surfaces. Consequently, we extend the grid of multicycle nova evolution models presented in Paper I almost to its limits, adding multicycle nova outburst calculations for a considerable number of new parameter combinations. In particular, the extended parameter pace that produces nova eruptions includes low mass transfer rates down to 5e-13 Msun/yr, and more models for low T_{WD}. Resulting characteristics of these runs are added to the former parameter combination results, to provide a full grid spanning the entire parameter space for Carbon-Oxygen white dwarfs. The full grid covers the entire range of observed nova characteristics, even those of peculiar objects, which have not been numerically reproduced until now. Most remarkably, runs for very low Mdot lead to very high values for some characteristics, such as outburst amplitude A>~20, high super-Eddington luminosities at maximum, heavy element abundance of the ejecta Z_{ej}~0.63 and high ejected masses m_{ej}~7e-4 Msun.Comment: Accepted for publication in ApJ - 04/2005. Complete grid results (Tables 2+3) data available at: http://geophysics.tau.ac.il/personal/oferya/ under "Publications

Por uma tipologia do ensino superior brasileiro: teste de conceito

Apesar de que a grande diferenciação que existe no ensino superior brasileiro seja amplamente conhecida, e que diferentes tipos de instituições tenham objetivos e produzam resultados também distintos, nas áreas de ensino de graduação, pós-graduação e pesquisa, essas diferenças não são reconhecidas com todas as suas implicações pela legislação nem pelo sistema de avaliação adotado pelo Ministério da Educação no Brasil. O público, formado por estudantes atuais e futuros, assim como por seus empregadores, tampouco é informado a respeito dessas diferenças. O objetivo deste trabalho é apresentar uma proposta de classificação ou tipologia das instituições de educação superior brasileiras que identifique com clareza essas diferenças, e que possa servir de base para um sistema de informações e procedimentos de avaliação que tomem em conta essa variedade de características, objetivos e resultados. Isso é feito agrupando-se instituições que tenham perfis semelhantes, do ponto de vista de seu porte, natureza jurídica e envolvimento com atividades de ensino e pós-graduação, e verificando-se até que ponto essas diferenças de tipos correspondem também a diferenças em relação às características de professores, alunos, áreas de atuação e atuação. Na última parte discutimos algumas implicações dessa tipologia para o sistema de avaliação da educação superior e, mais amplamente, para a melhoria da qualidade e desempenho da educação superior do país como um todo.Although the great differentiation that exists in Brazilian higher education is widely known, and even if different types of institutions have different objectives and produce different results in the undergraduate, graduate and research levels, the full implication of these differences is not recognized by the legislation or by the evaluation system adopted by the Ministry of Education in Brazil. Neither is the public, i.e., current and future students and their employers, informed of these differences. The objective of this work is to present a classification or typology proposal for Brazilian higher education institutions that clearly identifies these differences, and that can serve as a basis for a system of information and evaluation procedures that take into account this variety of characteristics, objectives and results. This is done by grouping institutions that have similar profiles, from the point of view of size, legal status and involvement with teaching and graduate activities, and assessing the extent to which differences in type correspond to differences in the characteristics of faculty, students, areas of activity and performance. In the final part, we discuss some implications of this typology for the higher education evaluation system and, more broadly, for improving the quality and performance of higher education in the country as a whole

Description of the Scenario Machine

We present here an updated description of the "Scenario Machine" code. This tool is used to carry out a population synthesis of binary stars. Previous version of the description can be found at http://xray.sai.msu.ru/~mystery//articles/review/contents.htmlComment: 32 pages, 3 figures. Corrected typo

Sensitivity of a VIRGO pair to stochastic GW backgrounds

The sensitivity of a pair of VIRGO interferometers to gravitational waves backgrounds (GW) of cosmological origin is analyzed for the cases of maximal and minimal overlap of the two detectors. The improvements in the detectability prospects of scale-invariant and non-scale-invariant logarithmic energy spectra of relic GW are discussed.Comment: 25 pages in RevTex style with 6 figure