Wearable System Based on Ultra-Thin Parylene C Tattoo Electrodes for EEG Recording

In an increasingly interconnected world, where electronic devices permeate every aspect of our lives, wearable systems aimed at monitoring physiological signals are rapidly taking over the sport and fitness domain, as well as biomedical fields such as rehabilitation and prosthetics. With the intent of providing a novel approach to the field, in this paper we discuss the development of a wearable system for the acquisition of EEG signals based on a portable, low-power custom PCB specifically designed to be used in combination with non-conventional ultra-conformable and imperceptible Parylene-C tattoo electrodes. The proposed system has been tested in a standard rest-state experiment, and its performance in terms of discrimination of two different states has been compared to that of a commercial wearable device for EEG signal acquisition (i.e., the Muse headset), showing comparable results. This first preliminary validation demonstrates the possibility of conveniently employing ultra-conformable tattoo-electrodes integrated portable systems for the unobtrusive acquisition of brain activity

Relativistic Hamiltonians in many-body theories

We discuss the description of a many-body nuclear system using Hamiltonians that contain the nucleon relativistic kinetic energy and potentials with relativistic corrections. Through the Foldy-Wouthuysen transformation, the field theoretical problem of interacting nucleons and mesons is mapped to an equivalent one in terms of relativistic potentials, which are then expanded at some order in 1/m_N. The formalism is applied to the Hartree problem in nuclear matter, showing how the results of the relativistic mean field theory can be recovered over a wide range of densities.Comment: 14 pages, uses REVTeX and epsfig, 3 postscript figures; a postscript version of the paper is available by anonymous ftp at ftp://carmen.to.infn.it/pub/depace/papers/951

HCG 16 Revisited: Clues About Galaxy Evolution in Groups

We present new spectroscopic observations of 5 galaxies, members of the unusually active compact group HCG 16, observed using the Palomar 5m telescope. The high signal to noise ratios (S/N $\sim 70$) of the spectra allow us to study the variation of the emission line characteristics and the stellar populations in the nucleus and the circumnuclear regions of the galaxies. The emission line characteristics of these galaxies are complex, varying between Seyfert 2 and LINERs or between LINERs and starbursts. All of the galaxies show traces of intermediate age stellar populations, supporting our previous result that post-starburst galaxies are common in compact groups. The galaxies HCG16--4 and HCG16--5 show double nuclei and therefore could be two cases of recent merger. Our observations support a scenario where HCG 16 was formed by the successive merger of metal poor, low mass galaxies. The galaxies HCG16--1 and HCG16--2, which are more evolved, form the old core of the group. Galaxies HCG16--4 and HCG16--5 are two more recent additions still in a merging phase. Galaxy HCG16--5 is a starburst galaxy which is just beginning to fall into the core. If HCG 16 is representative of compact groups in their early stage, the whole set of observations implies that the formation of compact groups is the result of hierarchical galaxy formation. HCG 16 could be one example of this process operating in the local universe.Comment: tar file containing text and figures is available at http://www.daf.on.br/~reinaldo/paper.htm

Constraints on a Universal IMF from UV to Near-IR Galaxy Luminosity Densities

We obtain constraints on the slope of a universal stellar initial mass function (IMF) over a range of cosmic star-formation histories (SFH) using z=0.1 luminosity densities in the range from 0.2 to 2.2 microns. The age-IMF degeneracy of integrated spectra of stellar populations can be broken for the Universe as a whole by using direct measurements of (relative) cosmic SFH from high-redshift observations. These have only marginal dependence on uncertainties in the IMF, whereas, fitting to local luminosity densities depends strongly on both cosmic SFH and the IMF. We fit to these measurements using population synthesis and find the best-fit IMF power-law slope to be Gamma=1.15+-0.2 (0.5 < M/M_solar < 120). This slope is in good agreement with the Salpeter IMF slope (Gamma=1.35). A strong upper limit of Gamma<1.7 is obtained which effectively rules out the Scalo IMF due to its too low fraction of high-mass stars. This upper limit is at the 99.7% confidence level if we assume a closed-box chemical evolution scenario and 95% if we assume constant solar metallicity. Fitting to the H-alpha line luminosity density, we obtain a best-fit IMF slope in good agreement with that derived from broadband measurements. Marginalizing over cosmic SFH and IMF slope, we obtain (95% conf. ranges, h=1): omega_stars = 1.1-2.0 E-3 for the stellar mass density; rho_sfr = 0.7-4.1 E-2 M_solar/yr/Mpc^3 for the star-formation rate density, and; rho_L = 1.2-1.7 E+35 W/Mpc^3 for the bolometric, attenuated, stellar, luminosity density (0.09-5 microns). Comparing this total stellar emission with an estimate of the total dust emission implies a relatively modest average attenuation in the UV (<=1 magnitude at 0.2 microns).Comment: 16 pages, accepted by Ap

New Measurements of Nucleon Structure Functions from the CCFR/NuTeV Collaboration

We report on the extraction of the structure functions F_2 and Delta xF_3 = xF_3nu-xF_3nubar from CCFR neutrino-Fe and antineutrino-Fe differential cross sections. The extraction is performed in a physics model independent (PMI) way. This first measurement for Delta xF_3, which is useful in testing models of heavy charm production, is higher than current theoretical predictions. The F_2 (PMI) values measured in neutrino and muon scattering are in good agreement with the predictions of Next to Leading Order PDFs (using massive charm production schemes), thus resolving the long-standing discrepancy between the two sets of data.Comment: 5 pages. Presented by Arie Bodek at the CIPNAP2000 Conference, Quebec City, May 200

Optical Spectral Signatures of Dusty Starburst Galaxies

We analyse the optical spectral properties of the complete sample of Very Luminous Infrared Galaxies presented by Wu et al. (1998a,b) and we find a high fraction (~50 %) of spectra showing both a strong H_delta line in absorption and relatively modest [OII] emission (e(a) spectra). The e(a) signature has been proposed as an efficient method to identify dusty starburst galaxies and we study the star formation activity and the nature of these galaxies, as well as the effects of dust on their observed properties. We examine their emission line characteristics, in particular their [OII]/H_alpha ratio, and we find this to be greatly affected by reddening. A search for AGN spectral signatures reveals that the e(a)'s are typically HII/LINER galaxies. We compare the star formation rates derived from the FIR luminosities with the estimates based on the H_alpha line and find that the values obtained from the optical emission lines are a factor of 10-70 (H_alpha) and 20-140 ([OII]) lower than the FIR estimates (50-300 M_sun yr^-1). We then study the morphological properties of the e(a) galaxies, looking for a near companion or signs of a merger/interaction. In order to explore the evolution of the e(a) population, we present an overview of the available observations of e(a)'s in different environments both at low and high redshift. Finally, we discuss the role of dust in determining the e(a) spectral properties and we propose a scenario of selective obscuration in which the extinction decreases with the stellar age.Comment: 26 pages, Latex, including 7 postscript figures, accepted for publication in the Astrophysical Journa