3,461 research outputs found
Time-Series Ensemble Photometry and the Search for Variable Stars in the Open Cluster M11
This work presents the first large-scale photometric variability survey of
the intermediate age (~200 Myr) open cluster M11. Thirteen nights of data over
two observing seasons were analyzed (using crowded field and ensemble
photometry techniques) to obtain high relative precision photometry. In this
study we focus on the detection of candidate member variable stars for
follow-up studies. A total of 39 variable stars were detected and can be
categorized as follows: 1 irregular (probably pulsating) variable, 6 delta
Scuti variables, 14 detached eclipsing binary systems, 17 W UMa variables, and
1 unidentified/candidate variable. While previous proper motion studies allow
for cluster membership determination for the brightest stars, we find that
membership determination is significantly hampered below V=15,R=15.5 by the
large population of field stars overlapping the cluster MS. Of the brightest
detected variables that have a high likelihood of cluster membership, we find
five systems where further work could help constrain theoretical stellar
models, including one potential W UMa member of this young cluster.Comment: 38 pages, 13 figures, accepted for December 2005 AJ, high-resolution
version available upon reques
Modelling the Inorganic Bromine Partitioning in the Tropical Tropopause over the Pacific Ocean
The stratospheric inorganic bromine burden (Bry) arising from the degradation of brominated very short-lived organic substances (VSL org ), and its partitioning between reactive and reservoir species, is needed for a comprehensive assessment of the ozone depletion potential of brominated trace gases. Here we present modelled inorganic bromine abundances over the Pacific tropical tropopause based on aircraft observations of VSL org of two campaigns of the Airborne Tropical TRopopause EXperiment (ATTREX 2013 carried out over eastern Pacific and ATTREX 2014 carried out over the western Pacific) and chemistry-climate simulations (along ATTREX flight tracks) using the specific meteorology prevailing. Using the Community Atmosphere Model with Chemistry (CAM-Chem), we model that BrO and Br are the daytime dominant species. Integrated across all ATTREX flights BrO represents ~ 43 % and 48 % of daytime Bry abundance at 17 km over the Western and Eastern Pacific, respectively. The results also show zones where Br/BrO >1 depending on the solar zenith angle (SZA), ozone concentration and temperature. On the other hand, BrCl and BrONO 2 were found to be the dominant night-time species with ~ 61% and 56 % of abundance at 17 km over the Western and Eastern Pacific, respectively. The western-to-eastern differences in the partitioning of inorganic bromine are explained by different abundances of ozone (O3), nitrogen dioxide (NO2) , and total inorganic chlorine (Cly).Fil: Navarro, MarĂa A.. University of Miami; Estados UnidosFil: Saiz-lopez, Alfonso. Consejo Superior de Investigaciones CientĂficas. Instituto de QuĂmica FĂsica; EspañaFil: Cuevas, Carlos Alberto. Consejo Superior de Investigaciones CientĂficas. Instituto de QuĂmica FĂsica; EspañaFil: Fernandez, Rafael Pedro. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - Mendoza; Argentina. Universidad Nacional de Cuyo. Facultad de Ciencias Exactas y Naturales; Argentina. Universidad Tecnologica Nacional. Facultad Regional Mendoza. SecretarĂa de Ciencia, TecnologĂa y Postgrado; ArgentinaFil: Atlas, Elliot. University of Miami; Estados UnidosFil: Rodriguez Lloeveras, Xavier. Consejo Superior de Investigaciones CientĂficas. Instituto de QuĂmica FĂsica; EspañaFil: Kinnison, Douglas E.. National Center For Atmospheric Research. Amospheric Chemistry DivisiĂłn; Estados UnidosFil: Lamarque, Jean Francois. National Center For Atmospheric Research. Amospheric Chemistry DivisiĂłn; Estados UnidosFil: Tilmes, Simone. National Center For Atmospheric Research. Amospheric Chemistry DivisiĂłn; Estados UnidosFil: Thornberry, Troy. State University of Colorado at Boulder; Estados Unidos. Earth System Research Laboratory; Estados UnidosFil: Rollins, Andrew. State University of Colorado at Boulder; Estados Unidos. Earth System Research Laboratory; Estados UnidosFil: Elkins, James W.. Earth System Research Laboratory; Estados UnidosFil: Hintsa, Eric J.. State University of Colorado at Boulder; Estados Unidos. Earth System Research Laboratory; Estados UnidosFil: Moore, Fred L.. State University of Colorado at Boulder; Estados Unidos. Earth System Research Laboratory; Estados Unido
On the difference of torus geometry between hidden and non-hidden broad line active galactic nuclei
We present results from the fitting of infrared (IR) spectral energy
distributions of 21 active galactic nuclei (AGN) with clumpy torus models. We
compiled high spatial resolution (-- arcsec) mid-IR -band
spectroscopy, -band imaging and nuclear near- and mid-IR photometry from the
literature. Combining these nuclear near- and mid-IR observations, far-IR
photometry and clumpy torus models, enables us to put constraints on the torus
properties and geometry. We divide the sample into three types according to the
broad line region (BLR) properties; type-1s, type-2s with scattered or hidden
broad line region (HBLR) previously observed, and type-2s without any published
HBLR signature (NHBLR). Comparing the torus model parameters gives us the first
quantitative torus geometrical view for each subgroup. We find that NHBLR AGN
have smaller torus opening angles and larger covering factors than those of
HBLR AGN. This suggests that the chance to observe scattered (polarized) flux
from the BLR in NHBLR could be reduced by the dual effects of (a) less
scattering medium due to the reduced scattering volume given the small torus
opening angle and (b) the increased torus obscuration between the observer and
the scattering region. These effects give a reasonable explanation for the lack
of observed HBLR in some type-2 AGN.Comment: 13 pages, 5 figures, accepted for publication in Ap
Proteolytic exposure of a cryptic site within collagen type IV is required for angiogenesis and tumor growth in vivo
Evidence is provided that proteolytic cleavage of collagen type IV results in the exposure of a functionally important cryptic site hidden within its triple helical structure. Exposure of this cryptic site was associated with angiogenic, but not quiescent, blood vessels and was required for angiogenesis in vivo. Exposure of the HUIV26 epitope was associated with a loss of α1ÎČ1 integrin binding and the gain of αvÎČ3 binding. A monoclonal antibody (HUIV26) directed to this site disrupts integrin-dependent endothelial cell interactions and potently inhibits angiogenesis and tumor growth. Together, these studies suggest a novel mechanism by which proteolysis contributes to angiogenesis by exposing hidden regulatory elements within matrix-immobilized collagen type IV
Inverse electron demand Diels-Alder click chemistry for pretargeted PET imaging and radioimmunotherapy
This approach leverages the rapid, bio-orthogonal inverse electron demand Diels-Alder reaction between a radiolabeled tetrazine and a trans-cyclooctene-bearing antibody to enable pretargeted positron emission tomography imaging and endoradiotherapy in a murine model of cancer. Radiolabeled antibodies have shown promise as tools for both the nuclear imaging and endoradiotherapy of cancer, but the protracted circulation time of radioimmunoconjugates can lead to high radiation doses to healthy tissues. To circumvent this issue, we have developed an approach to positron emission tomography (PET) imaging and radioimmunotherapy (RIT) predicated on radiolabeling the antibody after it has reached its target within the body. This in vivo pretargeting strategy is based on the rapid and bio-orthogonal inverse electron demand Diels-Alder reaction between tetrazine (Tz) and trans-cyclooctene (TCO). Pretargeted PET imaging and RIT using TCO-modified antibodies in conjunction with Tz-bearing radioligands produce high activity concentrations in target tissues as well as reduced radiation doses to healthy organs compared to directly labeled radioimmunoconjugates. Herein, we describe how to prepare a TCO-modified antibody (humanized A33-TCO) as well as how to synthesize two Tz-bearing radioligands: one labeled with the positron-emitting radiometal copper-64 ([Cu-64]Cu-SarAr-Tz) and one labeled with the beta-emitting radiolanthanide lutetium-177 ([Lu-177]Lu-DOTA-PEG(7)-Tz). We also provide a detailed description of pretargeted PET and pretargeted RIT experiments in a murine model of human colorectal carcinoma. Proper training in both radiation safety and the handling of laboratory mice is required for the successful execution of this protocol.Peer reviewe
Hospital survey on patient safety culture (HSOPSC) : a multi-method approach for target-language instrument translation, adaptation, and validation to improve the equivalence of meaning for cross-cultural research
Altres ajuts: This research project was partially funded through a research dissemination grant from the Universidad Cooperativa de Colombia received by Dr. Doriam E. Camacho-RodrĂguez.The Hospital Survey on Patient Safety Culture (HSOPSC) is widely utilized in multiple languages across the world. Despite culture and language variations, research studies from Latin America use the Spanish language HSOPSC validated for Spain and the United States. Yet, these studies fail to report the translation method, cultural adaptation process, and the equivalence assessment strategy. As such, the psychometric properties of the HSOPSC are not well demonstrated for cross-cultural research in Latin America, including Peru. The purpose of this study was to develop a target-language HSOPSC for cross-cultural research in Peru that asks the same questions, in the same manner, with the same intended meaning, as the source instrument. This study used a mixed-methods approach adapted from the translation guideline recommended by Agency for Healthcare Research and Quality. The 3-phase, 7-step process incorporated translation techniques, pilot testing, cognitive interviews, clinical participant review, and subject matter expert evaluation. The instrument was translated and evaluated in 3 rounds of cognitive interview (CI). There were 37 problem items identified in round 1 (14 clarity, 12 cultural, 11 mixed); and resolved to 4 problems by round 3. The pilot-testing language clarity inter-rater reliability was S-CVI/Avg = 0.97 and S-CVI/UA = 0.86; and S-CVI/Avg = 0.96 and S-CVI/UA = 0.83 for cultural relevance. Subject matter expert agreement in matching items to the correct dimensions was substantially equivalent (Kappa = 0.72). Only 1 of 12 dimensions had a low Kappa (0.39), borderline fair to moderate. The remaining dimensions performed well (7 = almost perfect, 2 = substantial, and 2 = moderate). The HSOPSC instrument developed for Peru was markedly different from the other Spanish-language versions. The resulting items were equivalent in meaning to the source, despite the new language and different cultural context. The analysis identified negatively worded items were problematic for target-language translation. With the limited literature about negatively worded items in the context of cross-cultural research, further research is necessary to evaluate this finding and the recommendation to include negatively worded items in instruments. This study demonstrates cross-cultural research with translated instruments should adhere to established guidelines, with cognitive interviews, based on evidence-based strategies
Science with an ngVLA: Resolving the Radio Complexity of EXor and FUor-type Systems with the ngVLA
Episodic accretion may be a common occurrence in the evolution of young
pre-main sequence stars and has important implications for our understanding of
star and planet formation. Many fundamental aspects of what drives the
accretion physics, however, are still unknown. The ngVLA will be a key tool in
understanding the nature of these events. The high spatial resolution, broad
spectral coverage, and unprecedented sensitivity will allow for the detailed
analysis of outburst systems. The proposed frequency range of the ngVLA allows
for observations of the gas, dust, and non-thermal emission from the star and
disk.Comment: 8 pages, 1 figure, To be published in the ASP Monograph Series,
"Science with a Next-Generation VLA", ed. E. J. Murphy (ASP, San Francisco,
CA
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