520 research outputs found
Does the Debris Disk around HD 32297 Contain Cometary Grains?
We present an adaptive optics imaging detection of the HD 32297 debris disk
at L' (3.8 \microns) obtained with the LBTI/LMIRcam infrared instrument at the
LBT. The disk is detected at signal-to-noise per resolution element ~ 3-7.5
from ~ 0.3-1.1" (30-120 AU). The disk at L' is bowed, as was seen at shorter
wavelengths. This likely indicates the disk is not perfectly edge-on and
contains highly forward scattering grains. Interior to ~ 50 AU, the surface
brightness at L' rises sharply on both sides of the disk, which was also
previously seen at Ks band. This evidence together points to the disk
containing a second inner component located at 50 AU. Comparing the
color of the outer (50 /AU ) portion of the disk at L' with
archival HST/NICMOS images of the disk at 1-2 \microns allows us to test the
recently proposed cometary grains model of Donaldson et al. 2013. We find that
the model fails to match the disk's surface brightness and spectrum
simultaneously (reduced chi-square = 17.9). When we modify the density
distribution of the model disk, we obtain a better overall fit (reduced
chi-square = 2.9). The best fit to all of the data is a pure water ice model
(reduced chi-square = 1.06), but additional resolved imaging at 3.1 \microns is
necessary to constrain how much (if any) water ice exists in the disk, which
can then help refine the originally proposed cometary grains model.Comment: Accepted to ApJ January 13, 2014. 12 pages (emulateapj style), 9
figures, 1 tabl
Misdiagnosing Melioidosis
Melioidosis is endemic in southern and Southeast Asia and northern Australia. Although relatively few indigenous cases are recognized in the Indian subcontinent, a substantial proportion of cases imported into the United Kingdom originate there, probably reflecting patterns of immigration and travel, and underdiagnosis within the Indian subcontinent
TLR2 Mediates Recognition of Live Staphylococcus epidermidis and Clearance of Bacteremia
Background: Staphylococcus epidermidis (SE) is a nosocomial pathogen that causes catheter-associated bacteremia in the immunocompromised, including those at the extremes of age, motivating study of host clearance mechanisms. SE-derived soluble components engage TLR2; but additional signaling pathways have also been implicated, and TLR2 can play complex, at times detrimental, roles in host defense against other Staphylococcal spp. The role of TLR2 in responses of primary blood leukocytes to live SE and in clearance of SE bacteremia, the most common clinical manifestation of SE infection, is unknown. Methodology/Principal Findings: We studied TLR2-mediated recognition of live clinical SE strain 1457 employing TLR2- transfected cells, neutralizing anti-TLR antibodies and TLR2-deficient mice. TLR2 mediated SE-induced cytokine production in human embryonic kidney cells, human whole blood and murine primary macrophages, in part via recognition of a soluble TLR2 agonist. After i.v. challenge with SE, early (1 h) cytokine/chemokine production and subsequent clearance of bacteremia (24-48 h) were markedly impaired in TLR2-deficient mice. Conclusions/Significance: TLR2 mediates recognition of live SE and clearance of SE bacteremia in vivo
Advancing clinical leadership to improve the implementation of evidence-based practice in surgery : a longitudinal mixed-method study protocol
Background:
Clinical leadership is fundamental in facilitating service improvements in healthcare. Few studies have attempted to understand or model the different approaches to leadership which are used when promoting the uptake and implementation of evidence-based interventions. This research aims to uncover and explain how distributed clinical leadership can be developed and improved to enhance the use of evidence in practice. In doing so, this study examines implementation leadership in orthopaedic surgery to explain leadership as a collective endeavour which cannot be separated from the organisational context.
Methods:
A mixed-method study consisting of longitudinal and cross-sectional interviews and an embedded social network analysis will be performed in six NHS hospitals. A social network analysis will be undertaken in each hospital to uncover the organisational networks, the focal leadership actors and information flows in each organisation. This will be followed by a series of repeated semi-structured interviews, conducted over 4 years, with orthopaedic surgeons and their professional networks. These longitudinal interviews will be supplemented by cross-sectional interviews with the national established surgical leaders. All qualitative data will be analysed using a constructivist grounded theory approach and integrated with the quantitative data. The participant narratives will enrich the social network to uncover the leadership configurations which exist, and how different configurations of leadership are functioning in practice to influence implementation processes and outcomes.
Discussion:
The study findings will facilitate understanding about how and why different configurations of leadership develop and under what organisational conditions and circumstances they are able to flourish. The study will guide the development of leadership interventions that are grounded in the data and aimed at advancing leadership for service improvement in orthopaedics. The strength of the study lies in the combination of multi-component, multi-site, multi-agent methods to examine leadership processes in surgery. The findings may be limited by the practical challenges of longitudinal qualitative data collection, such as ensuring participant retention, which need to be balanced against the theoretical and empirical insights generated through this comprehensive exploration of leadership across and within a range of healthcare organisations
Exposure to the antimicrobial peptide LL-37 produces dendritic cells optimized for immunotherapy
Immunization of patients with autologous, ex vivo matured dendritic cell (DC) preparations, in order to prime antitumor T-cell responses, is the focus of intense research. Despite progress and approval of clinical approaches, significant enhancement of these personalized immunotherapies is urgently needed to improve efficacy. We show that immunotherapeutic murine and human DC, generated in the presence of the antimicrobial host defense peptide LL-37, have dramatically enhanced expansion and differentiation of cells with key features of the critical CD103 + /CD141 + DC subsets, including enhanced cross-presentation and co-stimulatory capacity, and upregulation of CCR7 with improved migratory capacity. These LL-37-DC enhanced proliferation, activation and cytokine production by CD8 + (but not CD4 + ) T cells in vitro and in vivo. Critically, tumor antigen-presenting LL-37-DC increased migration of primed, activated CD8 + T cells into established squamous cell carcinomas in mice, and resulted in tumor regression. This advance therefore has the potential to dramatically enhance DC immunotherapy protocols
Evidence Against an Edge-On Disk Around the Extrasolar Planet 2MASS 1207 b and a New Thick Cloud Explanation for its Under-Luminosity
(Abridged) Since the discovery of the first directly-imaged, planetary-mass
object, 2MASS 1207 b, several works have sought to explain a disparity between
its observed temperature and luminosity. Given its known age, distance, and
spectral type, 2MASS 1207 b is under-luminous by a factor of ~10 (~2.5 mags)
when compared to standard models of brown-dwarf/giant-planet evolution. In this
paper, we study three possible sources of 2MASS 1207 b's under-luminosity.
First, we investigate Mohanty et al. (2007)'s hypothesis that a near edge-on
disk might be responsible for 2MASS 1207 b's under-luminosity. We conclude that
the hypothesis is unlikely due to the lack of variability seen in multi-epoch
photometry and unnecessary due to the increasing sample of under-luminous
brown-dwarfs/giant-exoplanets that cannot be explained by an edge-on disk.
Next, we test the analogous possibility that a spherical shell of dust, could
explain 2MASS 1207 b's under-luminosity. Models containing enough dust to
create ~2.5 mags of extinction, placed at reasonable radii, are ruled out by
our new Gemini/T-ReCS 8.7 micron photometric upper-limit for 2MASS 1207 b.
Finally, we investigate the possibility that 2MASS 1207 b is intrinsically
cooler than the commonly used AMES-DUSTY fits to its spectrum, and thus it is
not, in fact, under-luminous. New, thick cloud model grids by Madhusudhan et
al. (2011) fit 2MASS 1207 b's 1-10 micron SED well, but they do not quite fit
its near-infrared spectrum. However, we suggest that with some "tuning", they
might be capable of simultaneously reproducing 2MASS 1207 b's spectral shape
and luminosity. In this case, the whole class of young, under-luminous
brown-dwarfs/giant-exoplanets might be explained by atmospheres that are able
to suspend thick, dusty clouds in their photospheres at lower temperatures than
field brown-dwarfs.Comment: 35 pages, 9 figures, accepted to Ap
Morphology and distribution of scales, dermal ossifications, and other non-feather integumentary structures in non-avialan theropod dinosaurs
Modern birds are typified by the presence of feathers, complex evolutionary innovations that were already widespread in the group of theropod dinosaurs (Maniraptoriformes) that include crown Aves. Squamous or scaly reptilian-like skin is, however, considered the plesiomorphic condition for theropods and dinosaurs more broadly. Here, we review the morphology and distribution of non-feathered integumentary structures in non-avialan theropods, covering squamous skin and naked skin as well as dermal ossifications. The integumentary record of non-averostran theropods is limited to tracks, which ubiquitously show a covering of tiny reticulate scales on the plantar surface of the pes. This is consistent also with younger averostran body fossils, which confirm an arthral arrangement of the digital pads. Among averostrans, squamous skin is confirmed in Ceratosauria (Carnotaurus), Allosauroidea (Allosaurus, Concavenator, Lourinhanosaurus), Compsognathidae (Juravenator), and Tyrannosauroidea (Santanaraptor, Albertosaurus, Daspletosaurus, Gorgosaurus, Tarbosaurus, Tyrannosaurus), whereas dermal ossifications consisting of sagittate and mosaic osteoderms are restricted to Ceratosaurus. Naked, non-scale bearing skin is found in the contentious tetanuran Sciurumimus, ornithomimosaurians (Ornithomimus) and possibly tyrannosauroids (Santanaraptor), and also on the patagia of scansoriopterygids (Ambopteryx, Yi). Scales are surprisingly conservative among non-avialan theropods compared to some dinosaurian groups (e.g. hadrosaurids); however, the limited preservation of tegument on most specimens hinders further interrogation. Scale patterns vary among and/or within body regions in Carnotaurus, Concavenator and Juravenator, and include polarised, snake-like ventral scales on the tail of the latter two genera. Unusual but more uniformly distributed patterning also occurs in Tyrannosaurus, whereas feature scales are present only in Albertosaurus and Carnotaurus. Few theropods currently show compelling evidence for the co-occurrence of scales and feathers (e.g. Juravenator, Sinornithosaurus), although reticulate scales were probably retained on the mani and pedes of many theropods with a heavy plumage. Feathers and filamentous structures appear to have replaced widespread scaly integuments in maniraptorans. Theropod skin, and that of dinosaurs more broadly, remains a virtually untapped area of study and the appropriation of commonly used techniques in other palaeontological fields to the study of skin holds great promise for future insights into the biology, taphonomy and relationships of these extinct animals.Fil: Hendrickx, Christophe Marie Fabian. Fundación Miguel Lillo; Argentina. Consejo Nacional de Investigaciones CientÃficas y Técnicas. Centro CientÃfico Tecnológico - Tucumán. Unidad Ejecutora Lillo; ArgentinaFil: Bell, Phil R.. University Of New England; AustraliaFil: Pittman, Michael. Colegio Universitario de Londres; Reino UnidoFil: Milner, Andrew R. C.. No especifÃca;Fil: Cuesta Fidalgo, Elena. Bayerische Staatssammlung für Paläontologie und Geologie; AlemaniaFil: O'Connor, Jingmai. No especifÃca;Fil: Loewen, Mark. No especifÃca;Fil: Currie, Philip J.. University of Alberta; CanadáFil: Mateus, Octávio. Universidade Nova de Lisboa; PortugalFil: Kaye, Thomas G.. Foundation For Scientific Advancement; Estados UnidosFil: Delcourt, Rafael. Universidade Estadual de Campinas; Brasi
A Disk Around the Planetary-Mass Companion GSC 06214-00210 b: Clues About the Formation of Gas Giants on Wide Orbits
We present Keck/OSIRIS 1.1-1.8 um adaptive optics integral field spectroscopy
of the planetary-mass companion to GSC 06214-00210, a member of the ~5 Myr
Upper Scorpius OB association. We infer a spectral type of L0+/-1, and our
spectrum exhibits multiple signs of youth. The most notable feature is
exceptionally strong PaBeta emission (EW=-11.4 +/- 0.3 A) which signals the
presence of a circumplanetary accretion disk. The luminosity of GSC 06214-00210
b combined with its age yields a model-dependent mass of 14 +/- 2 MJup, making
it the lowest-mass companion to show evidence of a disk. With a projected
separation of 320 AU, the formation of GSC 06214-00210 b and other very
low-mass companions on similarly wide orbits is unclear. One proposed mechanism
is formation at close separations followed by planet-planet scattering to much
larger orbits. Since that scenario involves a close encounter with another
massive body, which is probably destructive to circumplanetary disks, it is
unlikely that GSC 06214-00210 b underwent a scattering event in the past. This
implies that planet-planet scattering is not solely responsible for the
population of gas giants on wide orbits. More generally, the identification of
disks around young planetary companions on wide orbits offers a novel method to
constrain the formation pathway of these objects, which is otherwise
notoriously difficult to do for individual systems. We also refine the spectral
type of the primary from M1 to K7 and detect a mild (2-sigma) excess at 22 um
using WISE photometry.Comment: 25 pages, 13 figures; Accepted by Ap
Clinical definitions of melioidosis.
Clinical definitions of melioidosis and inhalation-acquired melioidosis (Burkholderia pseudomallei infection) are described together with the evidence used to develop these definitions. Such definitions support accurate public health reporting, preparedness planning for deliberate B. pseudomallei release, design of experimental models, and categorization of naturally acquired melioidosis
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