10,793 research outputs found
Eelgrass in Estuarine Research Reserves Along the East Coast, USA
Eelgrass, Zostera marina L., is a submerged marine vascular plant that provides the basic structure of an extensive and important estuarine and coastal ecosystem. Currently, eelgrass populations around the world are declining dramatically due primarily to two causes: human pollution and a disease. The extensive loss of eelgrass threatens major alterations to the coastal environment and to the waterfowl and fish that depend on these plant communities. However, the eelgrass declines represent natural experiments that provide and opportunity to investigate a disease\u27s impact on an ecosystem, the characteristics of pollution-related declines, and finally, how declines from both causes can be diminished or mitigated
Nanoscale assembly processes revealed in the nacroprismatic transition zone of Pinna nobilis mollusc shells
Intricate biomineralization processes in molluscs engineer hierarchical
structures with meso-, nano-, and atomic architectures that give the final
composite material exceptional mechanical strength and optical iridescence on
the macroscale. This multiscale biological assembly inspires new synthetic
routes to complex materials. Our investigation of the prism-nacre interface
reveals nanoscale details governing the onset of nacre formation using
high-resolution scanning transmission electron microscopy. A wedge polishing
technique provides unprecedented, large-area specimens required to span the
entire interface. Within this region, we find a transition from nanofibrillar
aggregation to irregular early-nacre layers, to well-ordered mature nacre
suggesting the assembly process is driven by aggregation of nanoparticles
(~50-80 nm) within an organic matrix that arrange in fiber-like polycrystalline
configurations. The particle number increases successively and, when critical
packing is reached, they merge into early-nacre platelets. These results give
new insights into nacre formation and particle-accretion mechanisms that may be
common to many calcareous biominerals.Comment: 5 Figure
Recommended from our members
Overexpression of MMPs in Corneas Requiring Penetrating and Deep Anterior Lamellar Keratoplasty.
PurposeMatrix metalloproteinases (MMPs) comprise a family of zinc-dependent endopeptidases involved in wound healing processes, including neovascularization and fibrosis. We assessed MMP protein expression levels in diseased corneas of patients requiring penetrating and deep anterior lamellar keratoplasty. The purpose of this study was to test the hypothesis that upregulation of MMPs in diseased corneas is positively associated with clinical levels of corneal neovascularization and fibrosis.MethodsProtein expression levels of nine individual MMPs were quantified simultaneously in human corneal lysates by using the Bio-Plex Pro Human MMP 9-Plex Panel and the MAGPIX technology. Measurements of MMP1, MMP2, MMP3, MMP7, MMP8, MMP9, MMP10, MMP12, and MMP13 were performed on diseased specimens from 21 patients undergoing corneal transplantation (17 for penetrating keratoplasty and 4 for deep anterior lamellar keratoplasty) and 6 normal control corneas.ResultsLuminex-based expression analysis revealed a significant overexpression of four of the nine MMPs tested (MMP2, MMP8, MMP12, and MMP13) in patient samples compared to control. Significant overexpression of MMP1, MMP2, MMP8, MMP12, and MMP13 was observed in diseased corneas with neovascularization compared with diseased corneas without neovascularization. Overexpression of MMP1, MMP2, MMP8, MMP12, and MMP13 also corresponded with the levels of corneal fibrosis. Finally, reduced expression of MMP3 was detected in keratoconus patients.ConclusionsMultiple MMPs are expressed in the corneas of patients with chronic disease requiring keratoplasty even when the pathologic process appears to be clinically inactive. In particular, the expression of several MMPs (MMP2, MMP8, MMP12, and MMP13) is positively associated with increased levels corneal fibrosis and neovascularization
Cloning of terminal transferase cDNA by antibody screening
A cDNA library was prepared from a terminal deoxynucleotidyltransferase-containing thymoma in the phage vector λgt11. By screening plaques with anti-terminal transferase antibody, positive clones were identified of which some had β-galactosidase-cDNA fusion proteins identifiable after electrophoretic fractionation by immunoblotting with anti-terminal transferase antibody. The predominant class of cross-hybridizing clones was determined to represent cDNA for terminal transferase by showing that one representative clone hybridized to a 2200-nucleotide mRNA in close-matched enzyme-positive but not to enzyme-negative cells and that the cDNA selected a mRNA that translated to give a protein of the size and antigenic characteristics of terminal transferase. Only a small amount of genomic DNA hybridized to the longest available clone, indicating that the sequence is virtually unique in the mouse genome
ZNF804A genotype modulates neural activity during working memory for faces
Copyright © 2013 S. Karger AG, Basel.Peer reviewedPublisher PD
Anti-truncated stellar light profiles in the outer regions of STAGES spiral galaxies: bulge or disc related?
We present a comparison of azimuthally averaged radial surface brightness
mu(r) profiles and analytical bulge-disc decompositions (de Vaucouleurs,
r^(1/4) bulge plus exponential disc) for spiral galaxies using Hubble Space
Telescope/Advanced Camera for Surveys V-band imaging from the Space Telescope
A901/2 Galaxy Evolution Survey (STAGES). In the established classification
scheme, antitruncated mu(r) profiles (Type III) have a broken exponential disc
with a shallower region beyond the break radius r_brk. The excess light at
large radii (r > r_brk) can either be caused by an outer exponential disc (Type
III-d) or an extended spheroidal component (Type III-s). Using our comparisons,
we determine the contribution of bulge light at r > r_brk for a large sample of
78 (barred/unbarred, Sa-Sd) spiral galaxies with outer disc antitruncations
(mu_brk > 24 mag arcsec^-2). In the majority of cases (~85 per cent), evidence
indicates that excess light at r > r_brk is related to an outer shallow disc
(Type III-d). Here, the contribution of bulge light at r > r_brk is either
negligible (~70 per cent) or too little to explain the antitruncation (~15 per
cent). However in the latter cases, bulge light can affect the measured disc
properties (e.g. mu_brk, outer scalelength). In the remaining cases (~15 per
cent), light at r > r_brk is dominated by the bulge (Type III-s). Here, for
most cases the bulge profile dominates at all radii and only occasionally (3
galaxies, ~5 per cent) extends beyond that of a dominant disc and explains the
excess light at r > r_brk. We thus conclude that in the vast majority of cases
antitruncated outer discs cannot be explained by bulge light and thus remain a
pure disc phenomenon.Comment: Accepted to MNRA
The environmental dependence of the structure of outer galactic discs in STAGES spiral galaxies
We present an analysis of V-band radial surface brightness profiles for
spiral galaxies from the field and cluster environments using Hubble Space
Telescope/Advanced Camera for Surveys imaging and data from the Space Telescope
A901/2 Galaxy Evolution Survey (STAGES). We use a large sample of ~330 face-on
to intermediately inclined spiral galaxies and assess the effect of the galaxy
environment on the azimuthally averaged radial surface brightness mu profiles
for each galaxy in the outer stellar disc (24 < mu < 26.5 mag per sq arcsec).
For galaxies with a purely exponential outer disc (~50 per cent), we determine
the significance of an environmental dependence on the outer disc scalelength
h_out. For galaxies with a broken exponential in their outer disc, either
down-bending (truncation, ~10 per cent) or up-bending (anti-truncation, ~40 per
cent), we measure the strength T (outer-to-inner scalelength ratio,
log_10(h_out/h_in) of the mu breaks and determine the significance of an
environmental dependence on break strength T. Surprisingly, we find no evidence
to suggest any such environmental dependence on either outer disc scalelength
h_out or break strength T, implying that the galaxy environment is not
affecting the stellar distribution in the outer stellar disc. We also find that
for galaxies with small effective radii (r_e < 3 kpc) there is a lack of outer
disc truncations in both the field and cluster environments. Our results
suggest that the stellar distribution in the outer disc of spiral galaxies is
not significantly affected by the galaxy environment.Comment: Accepted to MNRAS. Appendix A available at
http://www.nottingham.ac.uk/~ppxdtm/STAGES_profiles_appendix.pd
The environmental dependence of the stellar mass-size relation in STAGES galaxies
We present the stellar mass-size relations for elliptical, lenticular, and
spiral galaxies in the field and cluster environments using HST/ACS imaging and
data from the Space Telescope A901/2 Galaxy Evolution Survey (STAGES). We use a
large sample of ~1200 field and cluster galaxies, and a sub-sample of cluster
core galaxies, and quantify the significance of any putative environmental
dependence on the stellar mass-size relation. For elliptical, lenticular, and
high-mass (log M*/M_sun > 10) spiral galaxies we find no evidence to suggest
any such environmental dependence, implying that internal drivers are governing
their size evolution. For intermediate/low-mass spirals (log M*/M_sun < 10) we
find evidence, significant at the 2-sigma level, for a possible environmental
dependence on galaxy sizes: the mean effective radius a_e for lower-mass
spirals is ~15-20 per cent larger in the field than in the cluster. This is due
to a population of low-mass large-a_e field spirals that are largely absent
from the cluster environments. These large-a_e field spirals contain extended
stellar discs not present in their cluster counterparts. This suggests the
fragile extended stellar discs of these spiral galaxies may not survive the
environmental conditions in the cluster. Our results suggest that internal
physical processes are the main drivers governing the size evolution of
galaxies, with the environment possibly playing a role affecting only the discs
of intermediate/low-mass spirals.Comment: 16 pages, 10 figures, accepted to MNRA
Open surgical partial nephrectomy for upper tract urothelial carcinoma
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/106973/1/iju12301.pd
Development of a Data Management Framework in Support of Southeastern Tidal Creek Research
2008 S.C. Water Resources Conference - Addressing Water Challenges Facing the State and Regio
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