Diffuse interstellar bands in fullerene planetary nebulae: the fullerenes - diffuse interstellar bands connection

We present high-resolution (R~15000) VLT/UVES optical spectra of two planetary nebulae (PNe; Tc 1 and M 1-20) where C60 (and C70) fullerenes have already been found. These spectra are of high-quality (S/N > 300) for PN Tc 1, which permits us to search for the expected electronic transitions of neutral C60 and diffuse interstellar bands (DIBs). Surprisingly, we report the non-detection of the most intense optical bands of C60 in Tc 1, although this could be explained by the low C60 column density estimated from the C60 infrared bands if the C60 emission peaks far away from the central star. The strongest and most common DIBs in both fullerene PNe are normal for their reddening. Interestingly, the very broad 4428 A DIB and the weaker 6309 A DIB are found to be unusually intense in Tc 1. We also report the detection of a new broad (FWHM~5 A) unidentified band at ~6525 A. We propose that the 4428 A DIB (probably also the 6309 A DIB and the new 6525 A band) may be related to the presence of larger fullerenes (e.g., C80, C240, C320, and C540) and buckyonions (multishell fullerenes such as C60@C240 and C60@C240@C540) in the circumstellar envelope of Tc 1.Comment: Accepted for publication in Astronomy & Astrophysics Letters (6 pages, 4 figures, and 1 Table

Low-pay higher pay and job satisfaction within the European Union: empirical evidence from fourteen countries

We examine differences in job satisfaction between low- and higher-paid workers within the European Union (EU). To do so The European Community Household Panel Data covering the period 1994-2001 is used. Then we test for differences in reported job satisfaction between low- and higher-paid workers. We also explain the existence of differences in the determinants of job satisfaction between these two types of workers and across countries. Our results indicate that low paid workers report a lower level of job satisfaction when compared with their higher paid counterparts in most countries, except in the UK. This supports the idea that low-wage employment in these countries mainly comprises low quality. The results also indicate that gap in average job satisfaction between low- and higher-paid workers is markedly wider in the Southern European countries than in the rest of EU. Finally, there are significant differences in the determinants of job satisfaction across countries. It seems then that a homogeneous policy may be inappropriate to increase satisfaction, and hence labour productivity, in the EU as a whole. Hence, an improvement of the quality of the jobs in the EU may require different policies. In particular, in some countries such as the United Kingdom removing low employment, namely through regulation, may worsen the workers’ well-being, although in other cases such a policy may lead to a totally different outcome.Job satisfaction,job quality,low-wage employment

Effect of the spin-orbit interaction on the thermodynamic properties of crystals: The specific heat of bismuth

In recent years, there has been increasing interest in the specific heat $C$ of insulators and semiconductors because of the availability of samples with different isotopic masses and the possibility of performing \textit{ab initio} calculations of its temperature dependence $C(T)$ using as a starting point the electronic band structure. Most of the crystals investigated are elemental (e.g., germanium) or binary (e.g., gallium nitride) semiconductors. The initial electronic calculations were performed in the local density approximation and did not include spin-orbit interaction. Agreement between experimental and calculated results was usually found to be good, except for crystals containing heavy atoms (e.g., PbS) for which discrepancies of the order of 20% existed at the low temperature maximum found for $C/T^3$. It has been conjectured that this discrepancies result from the neglect of spin-orbit interaction which is large for heavy atoms ($\Delta_0\sim$1.3eV for the $p$ valence electrons of atomic lead). Here we discuss measurements and \textit{ab initio} calculations of $C(T)$ for crystalline bismuth ($\Delta_0\sim$1.7 eV), strictly speaking a semimetal but in the temperature region accessible to us ($T >$ 2K) acting as a semiconductor. We extend experimental data available in the literature and notice that the \textit{ab initio} calculations without spin-orbit interaction exhibit a maximum at $\sim$8K, about 20% lower than the measured one. Inclusion of spin-orbit interaction decreases the discrepancy markedly: The maximum of $C(T)$ is now only 7% larger than the measured one. Exact agreement is obtained if the spin-orbit hamiltonian is reduced by a factor of $\sim$0.8.Comment: 4 pages, 3 figure

Wavefront curvature sensing for the human eye

In this paper we present a curvature wavefront sensor for the eye. The layout proposed is novel, whilst the algorithm used has been adapted from previously published work [Roddier, F.; Roddier, C. Appl. Opt. 1991, 30, 1325–1327]. The design of the set-up incorporates two field lenses that, together with a beam separator, define the distance Δz between the two sampled planes. We present a feasibility study to use this particular combination of optical configuration and retrieval algorithm in the eye. We present calibration curves and results from three real eyes

Mechanisms of nonlinear spin-wave emission from a microwave driven nanocontact

We present a micromagnetic study of linear and nonlinear spin-wave modes excited in an extended permalloy thin film by a microwave driven nanocontact. We show that the linear mode having the frequency equal to the excitation frequency (f) is driven by the ac Oersted field component perpendicular to the static external field (applied in-plane of the sample). The nonlinear mode with the frequency f /2 is excited as an independent eigenmode within a parametric longitudinal pumping process (due ac Oersted field component parallel to the bias field). Spectral positions of those modes are determined both in the space and phase domain. The results are important for the transfer of information coded into spin-waves between nanocontacts, and for synchronization of spin transfer torque nano-oscillators.Comment: 5 pages, 4 figure

A search for diffuse bands in fullerene planetary nebulae: evidence of diffuse circumstellar bands

Large fullerenes and fullerene-based molecules have been proposed as carriers of diffuse interstellar bands (DIBs). The recent detection of the most common fullerenes (C60 and C70) around some planetary nebulae (PNe) now enable us to study the DIBs towards fullerene-rich space environments. We search DIBs in the optical spectra towards three fullerene-containing PNe (Tc 1, M 1-20, and IC 418). Special attention is given to DIBs which are found to be unusually intense towards these fullerene sources. In particular, an unusually strong 4428A absorption feature is a common charateristic of fullerene PNe. Similar to Tc 1, the strongest optical bands of neutral C60 are not detected towards IC 418. Our high-quality (S/N > 300) spectra for PN Tc 1, together with its large radial velocity, permit us to search for the presence of diffuse bands of circumstellar origin, which we refer to as diffuse circumstellar bands (DCBs). We report the first tentative detection of two DCBs at 4428 and 5780 A in the fullerene-rich circumstellar environment around the PN Tc 1. Laboratory and theoretical studies of fullerenes in their multifarious manifestations (carbon onions, fullerene clusters, or even complex species formed by fullerenes and other molecules like PAHs or metals) may help solve the mystery of some of the diffuse band carriers.Comment: Accepted for publication in Astronomy & Astrophysics (16 pages, 10 figures, and 7 Tables); final version (changes regarding PN M 1-20 and language corrected

Pemphigoid and pemphigus antigens in cultured epidermal cells

Fractions of IgG from sera of patients with pemphigoid and pemphigus added to monolayer cultures of mouse epidermal cells resulted in a sparse distribution of cells. Direct immunofluorescence studies of these monolayers revealed epidermal cell surface antigens reacting with pemphigoid and pemphigus antibodies. We suggest that these antibodies may bind to epidermal cell surface antigenic molecules which are important in maintaining epidermal cell adhesion in culture.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/75759/1/j.1365-2133.1978.tb03581.x.pd

Effect of Replacing Lard with Tallow on Performance and Fat Digestibility in Early Weaned Pigs�

Animal Scienc