Nonequilibrium quantum fluctuation relations for harmonic systems in nonthermal environments

We formulate exact generalized nonequilibrium fluctuation relations for the quantum mechanical harmonic oscillator coupled to multiple harmonic baths. Each of the different baths is prepared in its own individual (in general nonthermal) state. Starting from the exact solution for the oscillator dynamics we study fluctuations of the oscillator position as well as of the energy current through the oscillator under general nonequilibrium conditions. In particular, we formulate a fluctuation-dissipation relation for the oscillator position autocorrelation function that generalizes the standard result for the case of a single bath at thermal equilibrium. Moreover, we show that the generating function for the position operator fullfills a generalized Gallavotti-Cohen-like relation. For the energy transfer through the oscillator, we determine the average energy current together with the current fluctuations. Finally, we discuss the generalization of the cumulant generating function for the energy transfer to nonthermal bath preparations.Comment: 21 page

The Oxygen Abundance of Nearby Galaxies from Sloan Digital Sky Survey Spectra

We have derived the oxygen abundance for a sample of nearby galaxies in the Data Release 5 of the Sloan Digital Sky Survey (SDSS) which possess at least two independent spectra of one or several HII regions with a detected [OIII]4363 auroral line. Since, for nearby galaxies, the [OII]3727 nebular line is out of the observed wavelength range, we propose a method to derive (O/H)_ff abundances using the classic Te method coupled with the ff relation. (O/H)_7325 abundances have also been determined, based on the [OII]7320,7330 line intensities, and using a small modification of the standard Te method. The (O/H)_ff and (O/H)_7325 abundances have been derived with both the one- and two-dimensional t_2 - t_3 relations. It was found that the (O/H)_ff abundances derived with the parametric two-dimensional t_2 - t_3 relation are most reliable. Oxygen abundances have been determined in 29 nearby galaxies, based on 84 individual abundance determinations in HII regions. Because of our selection methods, the metallicity of our galaxies lies in the narrow range 8.2 < 12 + log (O/H) < 8.4. The radial distribution of oxygen abundances in the disk of the spiral galaxy NGC 4490 is determined for the first time.Comment: 39 pages, 10 figures, 4 tables, accepted for publication in the Astrophysical Journa

Design and fabrication of a radiative actively cooled honeycomb sandwich structural panel for a hypersonic aircraft

The panel assembly consisted of an external thermal protection system (metallic heat shields and insulation blankets) and an aluminum honeycomb structure. The structure was cooled to temperature 442K (300 F) by circulating a 60/40 mass solution of ethylene glycol and water through dee shaped coolant tubes nested in the honeycomb and adhesively bonded to the outer skin. Rene'41 heat shields were designed to sustain 5000 cycles of a uniform pressure of + or - 6.89kPa (+ or - 1.0 psi) and aerodynamic heating conditions equivalent to 136 kW sq m (12 Btu sq ft sec) to a 422K (300 F) surface temperature. High temperature flexible insulation blankets were encased in stainless steel foil to protect them from moisture and other potential contaminates. The aluminum actively cooled honeycomb sandwich structural panel was designed to sustain 5000 cycles of cyclic in-plane loading of + or - 210 kN/m (+ or - 1200 lbf/in.) combined with a uniform panel pressure of + or - 6.89 kPa (?1.0 psi)

Ultraconserved words point to deep language ancestry across Eurasia

The search for ever deeper relationships among the World’s languages is bedeviled by the fact that most words evolve too rapidly to preserve evidence of their ancestry beyond 5,000 to 9,000 y. On the other hand, quantitative modeling indicates that some “ultraconserved” words exist that might be used to find evidence for deep linguistic relationships beyond that time barrier. Here we use a statistical model, which takes into account the frequency with which words are used in common everyday speech, to predict the existence of a set of such highly conserved words among seven language families of Eurasia postulated to form a linguistic superfamily that evolved from a common ancestor around 15,000 y ago. We derive a dated phylogenetic tree of this proposed superfamily with a time-depth of ∼14,450 y, implying that some frequently used words have been retained in related forms since the end of the last ice age. Words used more than once per 1,000 in everyday speech were 7- to 10-times more likely to show deep ancestry on this tree. Our results suggest a remarkable fidelity in the transmission of some words and give theoretical justification to the search for features of language that might be preserved across wide spans of time and geography

Chemical Properties of Star-Forming Emission Line Galaxies at z=0.1 - 0.5

We measure oxygen and nitrogen abundances for 14 star-forming emission line galaxies (ELGs) at 0.11<z<0.5 using Keck/LRIS optical spectroscopy. The targets exhibit a range of metallicities from slightly metal-poor like the LMC to super-solar. Oxygen abundances of the sample correlate strongly with rest-frame blue luminosities. The metallicity-luminosity relation based on these 14 objects is indistinguishable from the one obeyed by local galaxies, although there is marginal evidence (1.1sigma) that the sample is slightly more metal-deficient than local galaxies of the same luminosity. The observed galaxies exhibit smaller emission linewidths than local galaxies of similar metallicity, but proper corrections for inclination angle and other systematic effects are unknown. For 8 of the 14 objects we measure nitrogen-to-oxygen ratios. Seven of 8 systems show evidence for secondary nitrogen production, with log(N/O)> -1.4 like local spirals. These chemical properties are inconsistent with unevolved objects undergoing a first burst of star formation. The majority of the ELGs are presently ~4 magnitudes brighter and ~0.5 dex more metal-rich than the bulk of the stars in well-known metal-poor dwarf spheroidals such as NGC 205 and NGC 185, making an evolution between some ELGs and metal-poor dwarf spheroidals improbable. However, the data are consistent with the hypothesis that more luminous and metal-rich spheroidal galaxies like NGC 3605 may become the evolutionary endpoints of some ELGs. [abridged]Comment: 41 pages, w/12 figures, uses AASTeX aaspp4.sty, psfig.sty; To appear in The Astrophysical Journa

The oxygen abundance calibrations and N/O abundance ratios of ~40,000 SDSS star-forming galaxies

Using a large sample of 38,478 star-forming galaxies selected from the Second Data Release of the Sloan Digital Sky Survey database (SDSS-DR2), we derive analytical calibrations for oxygen abundances from several metallicity-sensitive emission-line ratios: [N II]/H_alpha, [O III]/[N II], [N II]/[O II], [N II]/[S II], [S II]/H_alpha, and [O III]/H_beta. This consistent set of strong-line oxygen abundance calibrations will be useful for future abundance studies. Among these calibrations, [N II]/[O II] is the best for metal-rich galaxies due to its independence on ionization parameter and low scatter. Dust extinction must be considered properly at first. These calibrations are more suitable for metal-rich galaxies (8.4<12+log(O/H)<9.3), and for the nuclear regions of galaxies. The observed relations are consistent with those expected from the photoionization models of Kewley & Dopita (2002). However, most of the observational data spread in a range of ionization parameter q from 1*10^7 to 8*10^7 cm s^{-1}, corresponding to logU= -3.5 to -2.5, narrower than that suggested by the models. We also estimate the (N/O) abundance ratios of this large sample of galaxies, and these are consistent with the combination of a "primary" and a dominant "secondary" components of nitrogen.Comment: 17 pages, 10 figures, 1 table. ApJ in pres

Near-Infrared Spectroscopy of 0.4<z<1.0 CFRS Galaxies: Oxygen Abundances, SFRs and Dust

Using new J-band VLT-ISAAC and Keck-NIRSPEC spectroscopy, we have measured Halpha and [NII] line fluxes for 0.47<z<0.92 CFRS galaxies which have [OII], Hbeta and [OIII]a line fluxes available from optical spectroscopy, to investigate how the properties of the star forming gas in galaxies evolve with redshift. We derive the extinction and oxygen abundances for the sample using a method based on a set of ionisation parameter and oxygen abundance diagnostics, simultaneously fitting the [OII], Hbeta,[OIII], Halpha, and [NII] line fluxes. The individual reddening measurements allow us to accurately correct the Halpha-based star formation rate (SFR) estimates for extinction. Our most salient conclusions are: a) in all 30 CFRS galaxies the source of gas ionisation is not due to AGN activity; b) we find a range of 0<AV<3, suggesting that it is important to determine the extinction for every single galaxy in order to reliably measure SFRs and oxygen abundances in high redshift galaxies; c) high values of [NII]/Halpha >0.1 for most (but not all) of the CFRS galaxies indicate that they lie on the high-metallicity branch of the R23 calibration; d) about one third of the 0.47<z<0.92 CFRS galaxies in our sample have lower metallicities than local galaxies with similar luminosities and star formation rates; e) comparison with a chemical evolution model indicates that these low metallicity galaxies are unlikely to be the progenitors of metal-poor dwarf galaxies at z~0.Comment: Accepted for publication in the Astrophysical Journa

Dissipative N - body code for galaxy evolution

The evolving galaxy is considered as a system of baryonic fragments embedded into the static dark nonbaryonic (DH) and baryonic (BH) halo and subjected to gravitational and viscous interactions. Although the chemical evolution of each separate fragment is treated in the frame of one -- zone close box model with instantaneous recycling, its star formation (SF) activity is a function of mean local gas density and, therefore, is strongly influenced by other interacting fragments. In spite of its simplicity this model provides a realistic description of the process of galaxy formation and evolution over the Hubble timescale.Comment: 11 pages, LaTeX, 7 figures, using the article.sty, expected in A&ApTr, 18, 83

Metallicity determination in gas-rich galaxies with semiempirical methods

A study of the precision of the semiempirical methods used in the determination of the chemical abundances in gas-rich galaxies is carried out. In order to do this the oxygen abundances of a total of 438 galaxies were determined using the electronic temperature, the $R_{23}$ and the P methods. The new calibration of the P method gives the smaller dispersion for the low and high metallicity regions, while the best numbers in the turnaround region are given by the $R_{23}$ method. We also found that the dispersion correlates with the metallicity. Finally, it can be said that all the semiempirical methods studied here are quite insensitive to metallicity with a value of $8.0\pm0.2$ dex for more than 50% of the total sample. \keywords{ISM: abundances; (ISM): H {\sc ii} regions}Comment: 26 pages, 9 figures and 2 tables. To appear at AJ, January 200

Chemical Evolution of Galaxies

Chemical evolution of galaxies brings together ideas on stellar evolution and nucleosynthesis with theories of galaxy formation, star formation and galaxy evolution, with all their associated uncertainties. In a new perspective brought about by the Hubble Deep Field and follow-up investigations of global star formation rates, diffuse background etc., it has become necessary to consider the chemical composition of dark baryonic matter as well as that of visible matter in galaxies.Comment: 6 pages, AAS LaTeX macros v5.0, Millennium Essay to appear in PASP, Feb 200