1,025,898 research outputs found
Counterion Effects on Nano-confined Metal-Drug-DNA Complexes
We have explored morphology of DNA molecules bound with Cu-complexes of
piroxicam molecules, a non-steroidal anti-inflammatory drug (NSAID), under
one-dimensional confinement of thin films and have studied the effect of
counterions present in a buffer. X-ray reflectivity at and away from the Cu K
absorption edge and atomic force microscopy studies reveal that confinement
segregates the drug molecules preferentially in a top layer of the DNA film,
and counterions enhance this segregation
К вопросу о периодизации развития профессиональной подготовки рабочих кадров в Украине
В статті проаналізовано різні схеми періодизації історії розвитку систем професійної підготовки робітничих кадрів в УкраїніВ статье проанализированы различные схемы периодизации истории развития систем профессиональной подготовки рабочих кадров в Украин
Subaru FOCAS survey of z=7-7.1 Ly{\alpha} emitters: a test for z >~ 7 Ly{\alpha} photometric luminosity functions
Recent observations of z >~ 7 Ly{\alpha} emitters (LAEs) have derived a
variety of Ly{\alpha} luminosity functions (LFs) with contradictory results,
evolution or non-evolution from z <~ 6, the epoch after reionization. This
could be because most of z >~ 7 LFs comprise photometric candidates and might
include some contaminations. We conducted the Subaru Telescope Faint Object
Camera And Spectrograph narrowband NB980 ({\lambda}c ~ 9800A, FWHM ~ 100A)
imaging and spectroscopy survey of z=7-7.1 LAEs to compare its
"contamination-free" result with z >~ 7 photometric Ly{\alpha} LFs previously
derived. We imaged the Subaru Deep Field and the sky around a cluster MS
1520.1+3002 and found one LAE candidate, but spectroscopy did not reveal
Ly{\alpha} though deep enough to detect it. We calculated the expected number
of LAEs in our survey, using five z=7 and three z=7.7 Ly{\alpha} LFs from
recent surveys. Seven of them are consistent with null detection
(0.1^{+1.8}_{-0.1}-1.1^{+2.2}_{-1.0} LAEs) within errors including Poisson
statistics and cosmic variance, but average values (0.7-1.1 LAEs) predicted
from one z=7 and two z=7.7 LFs among the seven indicate nearly a single
detection. The remaining one z=7 LF predicts 3.0^{+3.2}_{-2.0} LAEs. As to z=7,
the discrepancy likely comes from different LAE selection criteria. For z=7.7,
there are two possibilities; (1) If z=7.7 LAEs are somehow brighter in
Ly{\alpha} luminosity than lower redshift LAEs, z=7.7 LF is observed to be
similar to or higher than lower redshift LFs even if attenuated by neutral
hydrogen. (2) All/most of the z=7.7 candidates are not LAEs. This supports the
decline of LF from z ~ 6 to 7.7 and reionization at z ~ 6-7.7.Comment: Accepted for publication in Monthly Notices of the Royal Astronomical
Society, 2012 March 0
Polycyclic Aromatic Hydrocarbon and Emission Line Ratios in Active Galactic Nuclei and Starburst Galaxies
We study the Polycyclic Aromatic Hydrocarbons (PAH) bands, ionic emission
lines, and Mid-infrared continuum properties, in a sample of 171 emission line
galaxies taken from literature plus 15 new active galactic nuclei (AGN) Spitzer
spectra. The continuum shape steeply rises for longer wavelengths and can be
fitted with a warm blackbody distribution of T=150-300K. The brightest PAH
spectral bands (6.2, 7.7, 8.6, 11.3, and 12.7m) and the forbidden emission
lines of [Si II] 34.8m, [Ar II] 6.9, [S III] 18.7 and 33.4 were detected
in all the Starbursts and in ~80% of the Seyfert~2. Taking under consideration
only the PAH bands at 7.7m, 11.3m, and 12.7m we find they are
present in ~80% of the Seyfert 1, while only half of this type of activity show
the 6.2m and 8.6 PAH bands. The observed intensities ratios for neutral
and ionized PAHs (6.2/7.7 x 11.3/7.7) were compared to theoretical intensity
ratios, showing that AGNs have higher ionization fraction and larger PAH (> 180
carbon atoms) than SB galaxies. The ratio between the ionized (7.7) and the
neutral PAH bands (8.6 and 11.3) are distributed over different ranges for AGNs
and SB galaxies, suggesting that these ratios could depend on the ionization
fraction, as well as on the hardness of the radiation field. The ratio between
the 7.7 and 11.3 bands is nearly constant with the increase of [Ne III]15.5/[Ne
II], indicating that the fraction of ionized to neutral PAH bands does not
depend on the hardness of the radiation field. The equivalent width of both PAH
features show the same dependence with [Ne III]/[Ne II], suggesting that the
PAH, emitting either ionized (7.7) or neutral (11.3) bands, may be destroyed
with the increase of the hardness of the radiation field.Comment: Accepted by Ap
The Luminosity Function of Lyman alpha Emitters at Redshift z=7.7
Lyman alpha (Lya) emission lines should be attenuated in a neutral
intergalactic medium (IGM). Therefore the visibility of Lya emitters at high
redshifts can serve as a valuable probe of reionization at about the 50% level.
We present an imaging search for z=7.7 Lya emitting galaxies using an
ultra-narrowband filter (filter width= 9A) on the NEWFIRM imager at the Kitt
Peak National Observatory. We found four candidate Lya emitters in a survey
volume of 1.4 x 10^4 Mpc^3, with a line flux brighter than 6x10^-18 erg/cm^2/s
(5 sigma in 2" aperture). We also performed a detailed Monte-Carlo simulation
incorporating the instrumental effects to estimate the expected number of Lya
emitters in our survey, and found that we should expect to detect one Lya
emitter, assuming a non-evolving Lya luminosity function (LF) between z=6.5 and
z=7.7. Even if one of the present candidates is spectroscopically confirmed as
a z~8 Lya emitter, it would indicate that there is no significant evolution of
the Lya LF from z=3.1 to z~8. While firm conclusions would need both
spectroscopic confirmations and larger surveys to boost the number counts of
galaxies, we successfully demonstrate the feasibility of sensitive
near-infrared (1.06 um) narrow-band searches using custom filters designed to
avoid the OH emission lines that make up most of the sky background.Comment: Published in ApJ, 3 figure
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