4,129 research outputs found
A Morphological Assessment of Bovine Chondrocytes Cultured on Poly(Ethyl Methacrylate)/Tetrahydrofurfuryl Methacrylate
A heterocyclic methacrylate polymer system, PEMA/THFMA, has shown potential as a biomaterial for cartilage repair in a rabbit model and has properties making it suitable for use clinically. The ability of the polymer system, PEMA/THFMA, and a related system, PEMA/HEMA, to support chondrocytes in vitro was assessed by scanning electron microscopy. Chondrocytes adhered to the surface of the PEMA/THFMA by day one, having a rounded morphology and clustered appearance opposed to the ThermanoxÂź control, where the cells had spread out and become fibroblastic in appearance. The chondrocytes divided rapidly on the PEMA/ THFMA system by day three and had completely covered the surface by day seven. In contrast, chondrocytes did not adhere well to the more hydrophilic PEMA/ HEMA system. A few cells were seen on the surface by day one and by days three and seven, there was no evidence of cell growth or spreading across the surface.
In conclusion, the PEMA/THFMA system can support chondrocytes in vitro, whereas the PEMA/HEMA system does not
Dense Molecular Gas and the Role of Star Formation in the Host Galaxies of Quasi-Stellar Objects
New millimeter-wave CO and HCN observations of the host galaxies of
infrared-excess Palomar Green quasi-stellar objects (PG QSOs) previously
detected in CO are presented. These observations are designed to assess the
validity of using the infrared luminosity to estimate star formation rates of
luminous AGN by determining the relative significance of dust-heating by young,
massive stars and active galactic nuclei (AGN) in QSO hosts and IRAS galaxies
with warm, AGN-like infrared colors. The HCN data show the PG QSO host IZw1 and
most of the warm IRAS galaxies to have high L_IR / L'_HCN (>1600) relative to
the cool IRAS galaxy population for which the median L_IR / L'_HCN ~
890(+440,-470). If the assumption is made that the infrared emission from cool
IRAS galaxies is reprocessed light from embedded star-forming regions, then
high values of L_IR / L'_HCN are likely the result of dust heating by the AGN.
Further, if the median ratio of L'_HCN / L'_CO ~ 0.06 observed for Seyfert
galaxies and IZw1 is applied to the PG QSOs not detected in HCN, then the
derived L_IR / L'_HCN correspond to a stellar contribution to the production of
L_IR of ~ 7-39%, and star formation rates ~ 2-37 M_sun/yr are derived for the
QSO hosts. Alternatively, if the far-infrared is adopted as the star formation
component of the total infrared in cool galaxies, the stellar contributions in
QSO hosts to their L_FIR are up to 35% higher than the percentages derived for
L_IR. This raises the possibility that the L_FIR in several of the PG QSO
hosts, including IZw1, could be due entirely to dust heated by young, massive
stars. Finally, there is no evidence that the global HCN emission is enhanced
relative to CO in galaxies hosting luminous AGN.Comment: LaTex, 31 pages, including 9 postscript figures, AJ, in press
(December 2006
Fit for purpose? Pattern cutting and seams in wearables development
This paper describes how a group of practitioners and researchers are working across disciplines at Nottingham Trent University in the area of Technical Textiles. It introduces strands of ongoing enquiry centred around the development and application of stretch sensors on the body, focusing on how textile and fashion knowledge are being reflexively revealed in the collaborative development of seamful wearable concepts, and on the tensions between design philosophies as revealed by definitions of purpose. We discuss the current research direction of the Aeolia project, which seeks to exploit the literal gaps found in pattern cutting for fitted stretch garments towards experiential forms and potential interactions. Normative goals of fitness for purpose and seamlessness are interrogated and the potential for more integrated design processes, which may at first appear âupside downâ, is discussed
New Observations and a New Interpretation of CO(3--2) in IRAS F10214+4724
New observations with the IRAM interferometer of CO(3--2) from the highly
luminous galaxy IRAS F10214+4724 show the source is 1.5'' x <= 0.9'' ; they
display no evidence of any velocity gradient. This size, together with optical
and IR data that show the galaxy is probably gravitationally lensed, lead to a
new model for the CO distribution. In contrast to many lensed objects, we have
a good estimate of the intrinsic CO and far IR surface brightnesses, so we can
derive the CO and far IR/sub-mm magnifications. The CO is magnified 10 times
and has a true radius of 400 pc. and the far IR is magnified 13 times and has a
radius of 250 pc. The true far IR luminosity is 4 to 7e12 Lsun and the
molecular gas mass is 2e10 Msun . This is nearly an order of magnitude less
than previously estimated. Because the far IR magnification is lower than the
mid and near IR magnification, the intrinsic spectral energy distribution now
peaks in the far infrared. That is, nearly all of the energy of this object is
absorbed and re-emitted in the far infrared. In CO luminosity, molecular gas
content, CO linewidth, and corrected far IR luminosity, 10214+472 is a typical,
warm, IR ultraluminous galaxy.Comment: 18 pages, including 3 figures, of gzipped, uuencoded postscript. To
be published Ap.J. Letter
Novel Heterozygous Deletion in Retinol Dehydrogenase 12 (RDH12) Causes Familial Autosomal Dominant Retinitis Pigmentosa.
Mutations in the retinol dehydrogenase 12 (RDH12) gene are primarily associated with Leber congenital amaurosis (LCA) type 13, a severe early onset autosomal recessive retinal dystrophy. Only one family with a heterozygous variant, associated with mild retinitis pigmentosa (RP), has been reported. We report a novel heterozygous variant [(c.759del; p.(Phe254Leufsâ24)], resulting in a frameshift and premature termination identified in two unrelated individuals with familial autosomal dominant RP. Both heterozygous variants are associated with a late onset RP phenotype, suggesting a possible genotype-phenotype correlation
The Molecular Interstellar Medium in Ultraluminous Infrared Galaxies
We present CO observations of a large sample of ultraluminous IR galaxies out
to z = 0.3. Most of the galaxies are interacting, but not completed mergers.
All but one have high CO(1-0) luminosities, log(Lco [K-km/s-pc^2]) = 9.92 +/-
0.12. The dispersion in Lco is only 30%, less than that in the FIR luminosity.
The integrated CO intensity correlates Strongly with the 100 micron flux
density, as expected for a black body model in which the mid and far IR
radiation are optically thick. We use this model to derive sizes of the FIR and
CO emitting regions and the enclosed dynamical masses. Both the IR and CO
emission originate in regions a few hundred parsecs in radius. The median value
of Lfir/Lco = 160 Lsun/(K-km/s-pc^2), within a factor of two of the black body
limit for the observed FIR temperatures. The entire ISM is a scaled up version
of a normal galactic disk with densities a factor of 100 higher, making even
the intercloud medium a molecular region. Using three different techniques of
H2 mass estimation, we conclude that the ratio of gas mass to Lco is about a
factor of four lower than for Galactic molecular clouds, but that the gas mass
is a large fraction of the dynamical mass. Our analysis of CO emission reduces
the H2 mass from previous estimates of 2-5e10 Msun to 0.4-1.5e10 Msun, which is
in the range found for molecular gas rich spiral galaxies. A collision
involving a molecular gas rich spiral could lead to an ultraluminous galaxy
powered by central starbursts triggered by the compression of infalling
preexisting GMC's.Comment: 34 pages LaTeX with aasms.sty, 14 Postscript figures, submitted to
ApJ Higher quality versions of Figs 2a-f and 7a-c available by anonymous FTP
from ftp://sbast1.ess.sunysb.edu/solomon/
The structure of Onsala 1 star forming region
We present new high-sensitivity high-resolution mm-wave observations of the
Onsala 1 ultra-compact HII region that bring to light the internal structure of
this massive star forming cloud. The 1.2 mm continuum map obtained with the
IRAM 30-m radiotelescope (~11" resolution) shows a centrally peaked
condensation of 1' size (~0.5 pc at the assumed distance of 1.8 kpc) which has
been further investigated at higher resolution in the 3 mm continuum and in the
emission lines of H13CO+ J=1--0 and SiO J=2--1 with the IRAM Plateau de Bure
interferometer. The 3 mm data, with a resolution of ~5" X 4", displays a
unresolved continuum source at the peak of the extended 1.2 mm emission and
closely associated with the ultra-compact HII region. The H13CO+ map traces the
central condensation in good agreement with previous NH_3 maps of Zheng et al.
(1985). However, the velocity field of this central condensation, which was
previously thought to arise in a rapidly rotating structure, is better
explained in terms of the dense and compact component of a bipolar outflow.
This interpretation is confirmed by SiO and CO observations of the full region.
In fact, our new SiO data unveils the presence of multiple (at least 4)
outflows in the region. In particular, there is an important center of outflow
activity in the region at about 1' north of the UCHII region. Indeed the
different outflows are related to different members of the Onsala 1 cluster.
The data presented here support a scenario in which the phases of massive star
formation begin much later in the evolution of a cluster and/or UCHII region
last for much longer than 10^5 yrs.Comment: 6 pages and 3 figure
The Arp 220 merger on kpc scales
For the first time we study the Eastern nucleus in greater detail and search
for the more extended emission in the molecular gas in different CO line
transitions of the famous ULIRG Arp 220. Furthermore we present a model of the
merger in Arp 220 on large scales with the help of the CO data and an optical
and near-infrared composite HST image of the prototypical ULIRG. Using the
Plateau de Bure Interferometer (PdBI) we obtained CO(2-1) and (1-0) data at
wavelengths of 1 and 3 mm in 1994, 1996, 1997 and 2006 at different beam sizes
and spatial resolutions. The simulations of the merger in Arp 220 were
performed with the Identikit modeling tool. The model parameters that describe
the galaxy merger best give a mass ratio of 1:2 and result in a merger of
~6x10^8 yrs. The low resolution CO(1-0) PdBI observations suggest that there
are indications for emission ~10" towards the south, as well as to the north
and to the west of the two nuclei.Comment: accepted for publication in ApJ, 14 pages 10 figure
The faint counterparts of MAMBO mm sources near the NTT Deep Field
We discuss identifications for 18 sources from our MAMBO 1.2mm survey of the
region surrounding the NTT Deep Field. We have obtained accurate positions from
Very Large Array 1.4GHz interferometry and in a few cases IRAM mm
interferometry, and have also made deep BVRIzJK imaging at ESO. We find
thirteen 1.2mm sources associated with optical/near-infrared objects in the
magnitude range K=19.0 to 22.5, while five are blank fields at K>22. The median
redshift of the radio-identified mm sources is ~2.6 from the radio/mm
estimator, and the median optical/near-infrared photometric redshifts for the
objects with counterparts ~2.1. This suggests that those radio-identified mm
sources without optical/near-infrared counterparts tend to lie at higher
redshifts than those with optical/near-infrared counterparts. Compared to
published identifications of objects from 850micron surveys of similar depth,
the median K and I magnitudes of our counterparts are roughly two magnitudes
fainter and the dispersion of I-K colors is less. Real differences in the
median redshifts, residual mis-identifications with bright objects, cosmic
variance, and small number statistics are likely to contribute to this
significant difference, which also affects redshift measurement strategies. We
discuss basic properties of the near-infrared/(sub)mm/radio spectral energy
distributions of our galaxies and of interferometrically identified submm
sources from the literature. From a comparison with submm objects with
CO-confirmed spectroscopic redshifts we argue that roughly two thirds of the
(sub)mm galaxies are at z>~2.5. This fraction is probably larger when including
sources without radio counterparts. (abridged)Comment: 45 pages, 9 figures. Accepted by ApJ. The resolution of figures 2 and
3 has been degraded. A higher quality pdf version of this paper is available
at http://www.mpe.mpg.de/~dannerb
A Combined EIS-NVSS Survey Of Radio Sources (CENSORS) III: Spectroscopic observations
The Combined EIS-NVSS Survey Of Radio Sources (CENSORS) is a 1.4GHz radio
survey selected from the NRAO VLA Sky Survey (NVSS) and complete to a
flux-density of 7.2mJy. It targets the ESO Imaging Survey (EIS) Patch D, which
is a 3 by 2 square degree field centred on 09 51 36.0, -21 00 00 (J2000). This
paper presents the results of spectroscopic observations of 143 of the 150
CENSORS sources. The primary motivation for these observations is to achieve
sufficient spectroscopic completeness so that the sample may be used to
investigate the evolution of radio sources.
The observations result in secure spectroscopic redshifts for 63% of the
sample and likely redshifts (based on a single emission line, for example) for
a further 8%. Following the identification of the quasars and star-forming
galaxies in the CENSORS sample, estimated redshifts are calculated for the
remainder of the sample via the K-z relation for radio galaxies. Comparison of
the redshift distribution of the CENSORS radio sources to distributions
predicted by the various radio luminosity function evolution models of Dunlop &
Peacock 1990, results in no good match. This demonstrates that this sample can
be used to expand upon previous work in that field.Comment: Accepted for publication in MNRAS. This version has some reduced
resolution figures and 13 associated gif files. A version with all figures
incorporated (at full resolution) is available at
http://www.roe.ac.uk/~pnb/papers/censors_spectro.pd
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