117 research outputs found
A novel cyclosporin a aqueous formulation for dry eye treatment: in vitro and in vivo evaluation.
PURPOSE: The aim of the present study was the in vitro and in vivo evaluation of a novel aqueous formulation based on polymeric micelles for the topical delivery of cyclosporine A for dry eye treatment.
METHODS: In vitro experiments were carried out on primary rabbit corneal cells, which were characterized by immunocytochemistry using fluorescein-labeled lectin I/isolectin B4 for the endothelial cells and mouse monoclonal antibody to cytokeratin 3+12 for the epithelial ones. Living cells were incubated for 1 hour or 24 hours with a fluorescently labeled micelle formulation and analyzed by fluorescence microscopy. In vivo evaluations were done by Schirmer test, osmolarity measurement, CyA kinetics in tears, and CyA ocular distribution after topical instillation. A 0.05% CyA micelle formulation was compared to a marketed emulsion (Restasis).
RESULTS: The in vitro experiments showed the internalization of micelles in the living cells. The Schirmer test and osmolarity measurements demonstrated that micelles did not alter the ocular surface properties. The evaluation of the tear fluid gave similar CyA kinetics values: AUC = 2339 ± 1032 min*Όg/mL and 2321 ± 881.63; Cmax = 478 ± 111 Όg/mL and 451 ± 74; half-life = 36 ± 9 min and 28 ± 9 for the micelle formulation and Restasis, respectively. The ocular distribution investigation revealed that the novel formulation delivered 1540 ± 400 ng CyA/g tissue to the cornea.
CONCLUSIONS: The micelle formulation delivered active CyA into the cornea without evident negative influence on the ocular surface properties. This formulation could be applied for immune-related ocular surface diseases
The coronal line regions of planetary nebulae NGC6302 and NGC6537: 3-13um grating and echelle spectroscopy
We report on advances in the study of the cores of NGC6302 and NGC6537 using
infrared grating and echelle spectroscopy. In NGC6302, emission lines from
species spanning a large range of ionization potential, and in particular
[SiIX]3.934um, are interpreted using photoionization models (including CLOUDY),
which allow us to reestimate the central star's temperature to be about
250000K. All of the detected lines are consistent with this value, except for
[AlV] and [AlVI]. Aluminium is found to be depleted to one hundredth of the
solar abundance, which provides further evidence for some dust being mixed with
the highly ionized gas (with photons harder than 154eV). A similar depletion
pattern is observed in NGC6537. Echelle spectroscopy of IR coronal ions in
NGC6302 reveals a stratified structure in ionization potential, which confirms
photoionization to be the dominant ionization mechanism. The lines are narrow
(< 22km/s FWHM), with no evidence of the broad wings found in optical lines
from species with similar ionization potentials, such as [NeV]3426A. We note
the absence of a hot bubble, or a wind blown bipolar cavity filled with a hot
plasma, at least on 1'' and 10km/s scales. We also provide accurate new
wavelengths for several of the infrared coronal lines observed with the
echelle.Comment: Accepted for publication in MNRA
The Chemical Composition of the 30 Doradus Nebula Derived from VLT Echelle Spectrophotometry
Echelle spectrophotometry of the 30 Doradus nebula in the LMC is presented.
The data consists of VLT UVES observations in the 3100 to 10350 A range. The
intensities of 366 emission lines have been measured, including 269 identified
permitted lines of H 0, He 0, C 0, C+, N+, N++, O 0, O+, Ne 0, Ne+, S+, S++, Si
0 , Si+, Si++, Ar+, and Mg+. Electron temperatures and densities have been
determined using different line intensity ratios. The He+, C++, O+, and O++
ionic abundances have been derived from recombination lines, these abundances
are almost independent of the temperature structure of the nebula.
Alternatively abundances from collisionally excited lines have been derived for
a large number of ions of different elements, these abundances depend strongly
on the temperature structure. Accurate t^2 values have been derived from the
Balmer continuum, and by comparing the C++, O+, and O++ ionic abundances
obtained from collisionally excited and recombination lines. The chemical
composition of 30 Doradus is compared with those of Galactic and extragalactic
HII regions. The values of Delta Y / Delta O, Delta Y / Delta Z, and Yp are
also discussed.Comment: 37 pages, 2 figures, submitted to the Astrophysical Journa
Fermi Discovery of Gamma-Ray Emission from NGC 1275
We report the discovery of high-energy (E>100 MeV) gamma-ray emission from
NGC 1275, a giant elliptical galaxy lying at the center of the Perseus cluster
of galaxies, based on observations made with the Large Area Telescope (LAT) of
the Fermi Gamma ray Space Telescope. The positional center of the gamma-ray
source is only ~3' away from the NGC 1275 nucleus, well within the 95% LAT
error circle of ~5'.The spatial distribution of gamma-ray photons is consistent
with a point source. The average flux and power-law photon index measured with
the LAT from 2008 August 4 to 2008 December 5 are F_gamma = (2.10+-0.23)x
10^{-7} ph (>100 MeV) cm^{-2} s^{-1} and Gamma = 2.17+-0.05, respectively. The
measurements are statistically consistent with constant flux during the
four-month LAT observing period.Previous EGRET observations gave an upper limit
of F_gamma 100 MeV) cm^{-2} s^{-1} to the gamma-ray flux
from NGC 1275. This indicates that the source is variable on timescales of
years to decades, and therefore restricts the fraction of emission that can be
produced in extended regions of the galaxy cluster. Contemporaneous and
historical radio observations are also reported. The broadband spectrum of NGC
1275 is modeled with a simple one-zone synchrotron/synchrotron self-Compton
model and a model with a decelerating jet flow.Comment: 27 pages, 7 figures, Accepted for publication in the Astrophysical
Journa
A change in the optical polarization associated with a gamma-ray flare in the blazar 3C 279
It is widely accepted that strong and variable radiation detected over all
accessible energy bands in a number of active galaxies arises from a
relativistic, Doppler-boosted jet pointing close to our line of sight. The size
of the emitting zone and the location of this region relative to the central
supermassive black hole are, however, poorly known, with estimates ranging from
light-hours to a light-year or more. Here we report the coincidence of a
gamma-ray flare with a dramatic change of optical polarization angle. This
provides evidence for co-spatiality of optical and gamma-ray emission regions
and indicates a highly ordered jet magnetic field. The results also require a
non-axisymmetric structure of the emission zone, implying a curved trajectory
for the emitting material within the jet, with the dissipation region located
at a considerable distance from the black hole, at about 10^5 gravitational
radii.Comment: Published in Nature issued on 18 February 2010. Corresponding
authors: Masaaki Hayashida and Greg Madejsk
The Spectral Energy Distribution of Fermi bright blazars
(Abridged) We have conducted a detailed investigation of the broad-band
spectral properties of the \gamma-ray selected blazars of the Fermi LAT Bright
AGN Sample (LBAS). By combining our accurately estimated Fermi gamma-ray
spectra with Swift, radio, infra-red, optical and other hard X-ray/gamma-ray
data, collected within three months of the LBAS data taking period, we were
able to assemble high-quality and quasi-simultaneous Spectral Energy
Distributions (SED) for 48 LBAS blazars.The SED of these gamma-ray sources is
similar to that of blazars discovered at other wavelengths, clearly showing, in
the usual Log - Log F representation, the typical broad-band
spectral signatures normally attributed to a combination of low-energy
synchrotron radiation followed by inverse Compton emission of one or more
components. We have used these SEDs to characterize the peak intensity of both
the low and the high-energy components. The results have been used to derive
empirical relationships that estimate the position of the two peaks from the
broad-band colors (i.e. the radio to optical and optical to X-ray spectral
slopes) and from the gamma-ray spectral index. Our data show that the
synchrotron peak frequency is positioned between 10 and
10 Hz in broad-lined FSRQs and between and Hz in
featureless BL Lacertae objects.We find that the gamma-ray spectral slope is
strongly correlated with the synchrotron peak energy and with the X-ray
spectral index, as expected at first order in synchrotron - inverse Compton
scenarios. However, simple homogeneous, one-zone, Synchrotron Self Compton
(SSC) models cannot explain most of our SEDs, especially in the case of FSRQs
and low energy peaked (LBL) BL Lacs. (...)Comment: 85 pages, 38 figures, submitted to Ap
The 2009 multiwavelength campaign on Mrk 421: Variability and correlation studies
We performed a 4.5-month multi-instrument campaign (from radio to VHE gamma
rays) on Mrk421 between January 2009 and June 2009, which included VLBA,
F-GAMMA, GASP-WEBT, Swift, RXTE, Fermi-LAT, MAGIC, and Whipple, among other
instruments and collaborations. Mrk421 was found in its typical (non-flaring)
activity state, with a VHE flux of about half that of the Crab Nebula, yet the
light curves show significant variability at all wavelengths, the highest
variability being in the X-rays. We determined the power spectral densities
(PSD) at most wavelengths and found that all PSDs can be described by
power-laws without a break, and with indices consistent with pink/red-noise
behavior. We observed a harder-when-brighter behavior in the X-ray spectra and
measured a positive correlation between VHE and X-ray fluxes with zero time
lag. Such characteristics have been reported many times during flaring
activity, but here they are reported for the first time in the non-flaring
state. We also observed an overall anti-correlation between optical/UV and
X-rays extending over the duration of the campaign.
The harder-when-brighter behavior in the X-ray spectra and the measured
positive X-ray/VHE correlation during the 2009 multi-wavelength campaign
suggests that the physical processes dominating the emission during non-flaring
states have similarities with those occurring during flaring activity. In
particular, this observation supports leptonic scenarios as being responsible
for the emission of Mrk421 during non-flaring activity. Such a temporally
extended X-ray/VHE correlation is not driven by any single flaring event, and
hence is difficult to explain within the standard hadronic scenarios. The
highest variability is observed in the X-ray band, which, within the one-zone
synchrotron self-Compton scenario, indicates that the electron energy
distribution is most variable at the highest energies.Comment: Accepted for publication in A&A, 18 pages, 14 figures (v2 has a small
modification in the acknowledgments, and also corrects a typo in the field
"author" in the metadata
PKS 1502+106: a new and distant gamma-ray blazar in outburst discovered by the Fermi Large Area Telescope
The Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope
discovered a rapid (about 5 days duration), high-energy (E >100 MeV) gamma-ray
outburst from a source identified with the blazar PKS 1502+106 (OR 103, S3
1502+10, z=1.839) starting on August 05, 2008 and followed by bright and
variable flux over the next few months. Results on the gamma-ray localization
and identification, as well as spectral and temporal behavior during the first
months of the Fermi all-sky survey are reported here in conjunction with a
multi-waveband characterization as a result of one of the first Fermi
multi-frequency campaigns. The campaign included a Swift ToO (followed up by
16-day observations on August 07-22, MJD 54685-54700), VLBA (within the MOJAVE
program), Owens Valley (OVRO) 40m, Effelsberg-100m, Metsahovi-14m, RATAN-600
and Kanata-Hiroshima radio/optical observations. Results from the analysis of
archival observations by INTEGRAL, XMM-Newton and Spitzer space telescopes are
reported for a more complete picture of this new gamma-ray blazar.Comment: 17 pages, 11 figures, accepted for The Astrophysical Journa
Supermassive black holes, pseudobulges, and the narrow-line Seyfert 1 galaxies
We present HST/ACS observations of ten galaxies that host narrow-line Seyfert
1 (NLS1) nuclei, believed to contain relatively smaller mass black holes
accreting at high Eddington ratios. We deconvolve each ACS image into a nuclear
point source (AGN), a bulge, and a disk, and fitted the bulge with a Sersic
profile and the disk with an exponential profile. We find that at least five
galaxies can be classified as having pseudobulges. All ten galaxies lie below
the \mbh--L relation, confirming earlier results. Their locus is
similar to that occupied by pseudobulges. This leads us to conclude that the
growth of BHs in NLS1s is governed by secular processes rather than
merger-driven. Active galaxies in pseudobulges point to an alternative track of
black hole--galaxy co-evolution. Because of the intrinsic scatter in black hole
mass--bulge properties scaling relations caused by a combination of factors
such as the galaxy morphology, orientation, and redshift evolution, application
of scaling relations to determine BH masses may not be as straightforward as
has been hoped.Comment: Replaced with accepted versio
Coordinated Multiwavelength Observations of BL Lacertae in 2000
BL Lacertae was the target of an extensive multiwavelength monitoring
campaign in the second half of 2000. Simultaneous or quasi-simultaneous
observations were taken at radio (UMRAO and Metsaehovi) and optical(WEBT
collaboration) frequencies, in X-rays (BeppoSAX and RXTE), and at VHE
gamma-rays (HEGRA). The WEBT optical campaign achieved an unprecedented time
coverage, virtually continuous over several 10 - 20 hour segments. It revealed
intraday variability on time scales of ~ 1.5 hours and evidence for spectral
hardening associated with increasing optical flux. During the campaign, BL
Lacertae underwent a major transition from a rather quiescent state prior to
September 2000, to a flaring state for the rest of the year. This was also
evident in the X-ray activity of the source. BeppoSAX observations on July
26/27 revealed a rather low X-ray flux and a hard spectrum, while a BeppoSAX
pointing on Oct. 31 - Nov. 2, 2000, indicated significant variability on time
scales of < a few hours, and provided evidence for the synchrotron spectrum
extending out to ~ 10 keV during that time. During the July 26/27 observation,
there is a tantalizing, though not statistically significant, indication of a
time delay of ~ 4 - 5 hr between the BeppoSAX and the R-band light curve. Also,
a low-significance detection of a time delay of 15 d between the 14.5 GHz and
the 22 GHz radio light curves is reported. Several independent methods to
estimate the co-moving magnetic field in the source are presented, suggesting a
value of ~ 2 e_B^{2/7} G, where e_B is the magnetic-field equipartition factor
w.r.t. the electron energy density in the jet.Comment: Accepted for publication in Ap
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