Astron.J.132:117-136,2006 We study the evolution of the ionization state of the IGM at the end of the
reionization epoch using spectra of a sample of nineteen quasars at 5.74<z<6.42
discovered in the ...SDSS. Three methods are used to trace IGM properties: (a) the
evolution of the Gunn-Peterson optical depth in the Ly alpha,beta, and gamma;
(b) the distribution of dark absorption gaps, and (c) the size of HII regions
around quasars. We find that the evolution of the IGM accelerated at z>5.7: the
optical depth evolution changes from tau ~ (1+z)^{4.3} to (1+z)^{>11}, and the
average length of dark gaps with tau>3.5 increases from <10 to >80 comoving
Mpc. The dispersion of IGM properties along different lines of sight also
increases rapidly, implying fluctuations by a factor of >4 in the UV background
at z>6, when the mean free path of UV photons is comparable to the correlation
length of galaxies. The mean length of dark gaps shows the most dramatic
increase at z~6, as well as the largest varianace. We suggest using dark gap
statistics as a powerful probe of the ionization state of the IGM at yet higher
redshift. The sizes of HII regions around quasars decrease rapidly towards
higher redshift, suggesting that the neutral fraction of the IGM has increased
by a factor of >10 from z=5.7 to 6.4. The mass-averaged neutral fraction is
1-4% at z~6.2 based on the GP optical depth and HII region sizes. The
observations suggest that z~6 is the the end of the overlapping stage of
reionization, and are inconsistent with a neutral IGM at z~6, as indicated by
the finite length of dark absorption gaps.
We present a catalogue of morphologically classified bright galaxies in the north equatorial stripe (230 deg\(^2\)) derived from the Third Data Release of the Sloan Digital Sky Survey (SDSS). ...Morphological classification is performed by visual inspection of images in the \(g\) band. The catalogue contains 2253 galaxies complete to a magnitude limit of \(r=16\) after Galactic extinction correction, selected from 2658 objects that are judged as extended in the photometric catalogue in the same magnitude limit. 1866 galaxies in our catalogue have spectroscopic information. A brief statistical analysis is presented for the frequency of morphological types and mean colours in the catalogue. A visual inspection of the images reveals that the rate of interacting galaxies in the local Universe is approximately 1.5% in the \(r\le16\) sample. A verification is made for the photometric catalogue generated by the SDSS, especially as to its bright end completeness.
We measure the relation between galaxy luminosity and disk circular velocity (the Tully-Fisher TF relation), in the g, r, i, and z-bands, for a broadly selected sample of galaxies from the Sloan ...Digital Sky Survey, with the goal of providing well defined observational constraints for theoretical models of galaxy formation. The input sample of 234 galaxies has a roughly flat distribution of absolute magnitudes in the range -18.5 > Mr > -22, and our only morphological selection is an axis-ratio cut b/a < 0.6 to allow accurate inclination corrections. Long-slit spectroscopy yields usable H-alpha rotation curves for 162 galaxies. Observational errors, including distance errors due to peculiar velocities, are small compared to the intrinsic scatter of the TF relation. The slope of the forward TF relation steepens from -5.5 +/- 0.2 mag/log(km/s) in the g-band to -6.6 +/- 0.2 mag/log(km/s) in the z-band. The intrinsic scatter is approximately 0.4 mag in all bands. The scatter is not dominated by rare outliers or by any particular class of galaxies, though it drops slightly, to 0.36 mag, if we restrict the sample to nearly bulgeless systems. Correlations of TF residuals with other galaxy properties are weak: bluer galaxies are significantly brighter than average in the g-band but only marginally brighter in the i-band; more concentrated galaxies are slightly fainter than average; and the TF residual is virtually independent of half-light radius, contrary to the trend expected for gravitationally dominant disks. The observed residual correlations do not account for most of the intrinsic scatter, implying that this scatter is instead driven largely by variations in the ratio of dark to luminous matter within the disk galaxy population.
Using effective temperature and metallicity derived from SDSS spectra for ~60,000 F and G type main sequence stars (0.2<g-r<0.6), we develop polynomial models for estimating these parameters from the ...SDSS u-g and g-r colors. We apply this method to SDSS photometric data for about 2 million F/G stars and measure the unbiased metallicity distribution for a complete volume-limited sample of stars at distances between 500 pc and 8 kpc. The metallicity distribution can be exquisitely modeled using two components with a spatially varying number ratio, that correspond to disk and halo. The two components also possess the kinematics expected for disk and halo stars. The metallicity of the halo component is spatially invariant, while the median disk metallicity smoothly decreases with distance from the Galactic plane from -0.6 at 500 pc to -0.8 beyond several kpc. The absence of a correlation between metallicity and kinematics for disk stars is in a conflict with the traditional decomposition in terms of thin and thick disks. We detect coherent substructures in the kinematics--metallicity space, such as the Monoceros stream, which rotates faster than the LSR, and has a median metallicity of Fe/H=-0.96, with an rms scatter of only ~0.15 dex. We extrapolate our results to the performance expected from the Large Synoptic Survey Telescope (LSST) and estimate that the LSST will obtain metallicity measurements accurate to 0.2 dex or better, with proper motion measurements accurate to ~0.2 mas/yr, for about 200 million F/G dwarf stars within a distance limit of ~100 kpc (g<23.5). abridged
Preface discusses the concept of an 'Inter-Century Seminar.' It is followed by the author's Acknowledgements. The Introduction is by D. W. Malott. 'The Setting: Centennial at Kansas,' describes the ...background & the setting for the centennial celebration of the U of Kansas. (1) 'Man, Time, and Prophecy,' by L. C. Eiseley (U of Pennsylvania, Philadelphia), discusses the pattern of life for modern man. It diff'iates between the psychol'al mind of the classical world & the mind of the present. (2) 'The Continuing Scientific Revolution,' by P. H. Abelson (Ed, Science), presents an analysis of the role of sci & progress. The sci'fic work of Benjamin Franklin is discussed. The sci'fic revolution is delineated into: (a) chemical, (b) electronic, (c) agri'al, (d) Med, & (e) energy revolutions. The problem of the relationship between the economy & natural resources is presented. (3) 'An Appeal to Reason,' by C. E. Whittaker (US Supreme Court Justice), presents notions on the division of modern society into ideological & pol'al groups. Civil Rights in the US are discussed. (4) 'Prospects for Humanity,' by R. B. Fuller (Southern Illinois U, Carbondale), is an assessment of the trends which emerge from today's society. A discussion of the theories of T. Malthus & K. Marx is presented. An analysis of U students is presented. (5) 'Man and the World Community in the Century Ahead,' by A. Larson (Duke U, Durham, NC), criticizes the predictions of the physical sci's of the future world, because they overlook the pol'al, econ & soc realms. The novels of H. G. Wells, J. Verne, & G. Orwell are discussed. (6) 'Has the Theater a Future ?' by H. Clurman is a discussion of the relevance & the future of the theatrical world. (7) 'Our Crimes Against Criminals: A Plea,' by K. Menninger (Menninger Foundation, Topeka, Kan), discusses the treatment of the mentally ill, & the instit'al educ provided by the state of Kansas. (8) 'Explorations in Tomorrow,' by A. C. Clarke delineates 3 aspects of the future as: (i) the exploration of space, (ii) the exploration of the sea, & (iii) the exploration of the mind. (9) 'The Changed and Changing University,' by F. D. Murphy (U of Kansas, Lawrence), is a discussion of the higher educ'al system in the US. Biographical notes on the Inter-Century Seminar participants are included. No Index. G. Satt.
We study the spatial variation of galaxy number counts using five band
photometric images from the Sloan Digital Sky Survey. The spatial variation of
this sample of 46 million galaxies collected from ...2200 sq. degrees can be
understood as the combination of Galactic extinction and large-scale
clustering. With the use of the reddening map of Schlegel, Finkbeiner & Davis
(1998), the standard extinction law is verified for the colour bands from u to
z within 5% in the region of small extinction values, E(B-V)<0.15. The residual
spatial variations of the number counts suggests that the error of global
calibration for SDSS photometry is smaller than 0.02 mag.
The objective was to study the effects of a commercial pyrethroid-based pour-on product, permethrin, on reproductive performance in superovulated beef heifers by assessing steroid biosynthesis and ...embryo quality. Nonpregnant, yearling beef heifers (n = 10; 418 ± 33 kg; 5.5 ± 0.2 body conditioning scores) were assigned by body weight and breed to either (1) saline control or (2) permethrin pour-on administered at label dose (PYR). Superovulation was achieved on all heifers using a timed, 17-day, CIDR-based protocol with GnRH and PGF2α and decreasing total dosage of 240-mg FSH administered twice daily for 4 days. Heifers were artificially inseminated twice (at onset of estrus and 12 hours later) by same technician with frozen semen from single bull collection. To determine short- and long-term effects of permethrin on embryo quality and steroid biosynthesis, superovulation was initiated twice with collection of embryos occurring at 17 and 51 days after treatment. Embryos were recovered 6.5 days after first artificial insemination via nonsurgical flush and were evaluated by International Embryo Transfer Society standards. Blood was collected at standing estrus and day of embryo recovery. Estradiol (E2) and progesterone (P4) concentrations were analyzed via RIA. MIXED and GLIMMIX procedures of SAS were used to analyze continuous and categorical data, respectively. Heifer per flush was the experimental unit. Total embryos recovered did not differ because of treatment (P = 0.30), but did decrease in flush 2 compared with flush 1 (P = 0.02). Quality grade, total transferable quality embryos, and overall flush success did not differ because of treatment (P ≥ 0.16). However, transferable quality embryos were decreased in flush 2 compared with flush 1 (P = 0.05). Total unfertilized oocytes were greater in saline control (P = 0.04). The PYR heifers tended to have less total P4 (P = 0.15) and P4 per CL (P = 0.06) at recovery. E2 per ovulated follicle and E2 per total ovarian structure was greater in flush 2 (P ≤ 0.03) but did not differ because of treatment (P ≥ 0.23). In summary, these data indicate that permethrin administration at label dose in superovulated beef heifers has a tendency to reduce P4, but embryo quality is not affected.
The relationship between respiratory function at hospital discharge and the severity of later respiratory disease in extremely low gestational age neonates is not well defined.
To test the hypothesis ...that tidal breathing measurements near the time of hospital discharge differ between extremely premature infants with bronchopulmonary dysplasia (BPD) or respiratory disease in the first year of life and those without these conditions.
Study subjects were part of the PROP (Prematurity and Respiratory Outcomes Program) study, a longitudinal cohort study of infants born at less than 29 gestational weeks followed from birth to 1 year of age. Respiratory inductance plethysmography was used for tidal breathing measurements before and after inhaled albuterol 1 week before anticipated hospital discharge. Infants were breathing spontaneously and were receiving less than or equal to 1 L/min nasal cannula flow at 21% to 100% fraction of inspired oxygen. A survey of respiratory morbidity was administered to caregivers at 3, 6, 9, and 12 months corrected age to assess for respiratory disease. We compared tidal breathing measurements in infants with and without BPD (oxygen requirement at 36 wk) and with and without respiratory disease in the first year of life. Measurements were also performed in a comparison cohort of term infants.
A total of 765 infants survived to 36 weeks postmenstrual age, with research-quality tidal breathing data in 452 out of 564 tested (80.1%). Among these 452 infants, the rate of postdischarge respiratory disease was 65.7%. Compared with a group of 18 term infants, PROP infants had abnormal tidal breathing patterns. However, there were no clinically significant differences in tidal breathing measurements in PROP infants who had BPD or who had respiratory disease in the first year of life compared with those without these diagnoses. Bronchodilator response was not significantly associated with respiratory disease in the first year of life.
Extremely premature infants receiving less than 1 L/min nasal cannula support at 21% to 100% fraction of inspired oxygen have tidal breathing measurements that differ from term infants, but these measurements do not differentiate those preterm infants who have BPD or will have respiratory disease in the first year of life from those who do not. Clinical trial registered with www.clinicaltrials.gov (NCT01435187).
Astron.J.128:515,2004 We present the discovery of five new quasars at z>5.7, selected from the
multicolor imaging data of the Sloan Digital Sky Survey (SDSS). Three of them,
at redshifts 5.93, 6.07, ...and 6.22, were selected from ~1700 deg^2 of new SDSS
Main Survey imaging in the Northern Galactic Cap. An additional quasar, at
redshift 5.85, was discovered by coadding the data obtained in the Fall
Equatorial Stripe in the SDSS Southern Survey Region. The fifth object, at
redshift 5.80, is selected from a non-standard SDSS scan in the Southern
Galactic Cap outside the Main Survey area. The spectrum of SDSS
J162331.81+311200.5 (z=6.22) shows a complete Gunn-Peterson trough at z_abs >
5.95, similar to the troughs detected in other three z>6.2 quasars known. We
present a composite spectrum of the z>5.7 quasars discovered in the SDSS to
date. The average emission line and continuum properties of z~6 quasars exhibit
no significant evolution compared to those at low redshift. Using a complete
sample of nine z>5.7 quasars, we find that the density of quasars with M_1450 <
-26.7 at z~6 is (6+/-2) x 10^-10 per Mpc^3 consistent with our previous
estimates. The luminosity distribution of the sample is fit with a power law
luminosity function Psi(L) ~ L^(-3.2+/-0.7), somewhat steeper than but
consistent with our previous estimates.
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