49 research outputs found
bRing: An observatory dedicated to monitoring the Pictoris b Hill sphere transit
Aims. We describe the design and first light observations from the
Pictoris b Ring ("bRing") project. The primary goal is to detect photometric
variability from the young star Pictoris due to circumplanetary
material surrounding the directly imaged young extrasolar gas giant planet
\bpb. Methods. Over a nine month period centred on September 2017, the Hill
sphere of the planet will cross in front of the star, providing a unique
opportunity to directly probe the circumplanetary environment of a directly
imaged planet through photometric and spectroscopic variations. We have built
and installed the first of two bRing monitoring stations (one in South Africa
and the other in Australia) that will measure the flux of Pictoris,
with a photometric precision of over 5 minutes. Each station uses two
wide field cameras to cover the declination of the star at all elevations.
Detection of photometric fluctuations will trigger spectroscopic observations
with large aperture telescopes in order to determine the gas and dust
composition in a system at the end of the planet-forming era. Results. The
first three months of operation demonstrate that bRing can obtain better than
0.5\% photometry on Pictoris in five minutes and is sensitive to
nightly trends enabling the detection of any transiting material within the
Hill sphere of the exoplanet
A Genetic Basis of Susceptibility to Acute Pyelonephritis
For unknown reasons, urinary tract infections (UTIs) are clustered in certain individuals. Here we propose a novel, genetically determined cause of susceptibility to acute pyelonephritis, which is the most severe form of UTI. The IL-8 receptor, CXCR1, was identified as a candidate gene when mIL-8Rh mutant mice developed acute pyelonephritis (APN) with severe tissue damage.We have obtained CXCR1 sequences from two, highly selected APN prone patient groups, and detected three unique mutations and two known polymorphisms with a genotype frequency of 23% and 25% compared to 7% in controls (p<0.001 and p<0.0001, respectively). When reflux was excluded, 54% of the patients had CXCR1 sequence variants. The UTI prone children expressed less CXCR1 protein than the pediatric controls (p<0.0001) and two sequence variants were shown to impair transcription.The results identify a genetic innate immune deficiency, with a strong link to APN and renal scarring
Depauperate Avifauna in Plantations Compared to Forests and Exurban Areas
Native forests are shrinking worldwide, causing a loss of biological diversity. Our ability to prioritize forest conservation actions is hampered by a lack of information about the relative impacts of different types of forest loss on biodiversity. In particular, we lack rigorous comparisons of the effects of clearing forests for tree plantations and for human settlements, two leading causes of deforestation worldwide. We compared avian diversity in forests, plantations and exurban areas on the Cumberland Plateau, USA, an area of global importance for biodiversity. By combining field surveys with digital habitat databases, and then analyzing diversity at multiple scales, we found that plantations had lower diversity and fewer conservation priority species than did other habitats. Exurban areas had higher diversity than did native forests, but native forests outscored exurban areas for some measures of conservation priority. Overall therefore, pine plantations had impoverished avian communities relative to both native forests and to exurban areas. Thus, reports on the status of forests give misleading signals about biological diversity when they include plantations in their estimates of forest cover but exclude forested areas in which humans live. Likewise, forest conservation programs should downgrade incentives for plantations and should include settled areas within their purview
Formal and Informal Financing Decisions of Small Businesses
This study investigates small businesses’ financing decisions. Drawing upon asymmetric information theory, institutional theory and relevant literature on cognitive financial constraints, human capital and social capital, we propose a theoretical framework in which financing determinants come from three dimensions: entrepreneurs’ individual factors, organisational (firm-level) factors and contextual (institutional) factors. We employ this model to distinguish four types of firms: (1) firms that use no external finance, (2) firms that use informal finance only, (3) firms that use formal finance only and (4) firms that use both formal and informal finance. An empirical test on Vietnamese small businesses shows that factors from all three dimensions are important in understanding small businesses’ financing decisions
bRing: An observatory dedicated to monitoring the β Pictoris b Hill sphere transit
Aims. We describe the design and first light observations from the β Pictoris b Ring ("bRing") project. The primary goal is to detect photometric variability from the young star β Pictoris due to circumplanetary material surrounding the directly imaged young extrasolar gas giant planet β Pictoris b. Methods. Over a nine month period centred on September 2017, the Hill sphere of the planet will cross in front of the star, providing a unique opportunity to directly probe the circumplanetary environment of a directly imaged planet through photometric and spectroscopic variations. We have built and installed the first of two bRing monitoring stations (one in South Africa and the other in Australia) that will measure the flux of β Pictoris, with a photometric precision of 0.5% over 5 min. Each station uses two wide field cameras to cover the declination of the star at all elevations. Detection of photometric fluctuations will trigger spectroscopic observations with large aperture telescopes in order to determine the gas and dust composition in a system at the end of the planet-forming era. Results. The first three months of operation demonstrate that bRing can obtain better than 0.5% photometry on β Pictoris in five minutes and is sensitive to nightly trends enabling the detection of any transiting material within the Hill sphere of the exoplanet.M.A.K., R.S., P.D. gratefully acknowledge funding from
NOVA and Leiden Observatory. We thank the NWO/NRF for travel funding for
this project. S.M.C., and B.B.D.L. thank NRF PDP. This work is based on the research supported by the National Research Foundation. This research made
use of Astropy, a community-developed core Python package for Astronomy
(Astropy Collaboration et al. 2013). We thank the SAAO operations/technical
staff for their logistical support in the commissioning of bRing in Sutherland.E.E.M. and S.N.M. acknowledge support from the NASA NExSS program. Construction of the bRing observatory to be sited at Siding Springs, Australia would not be possible without a University of Rochester University Research Award, help from Mike Culver and Rich Sarkis (UR), and generous donations of time, services, and materials from Joe and Debbie Bonvissuto of Freight Expediters, Michael Akkaoui and his team at Tanury Industries, Robert Harris and Michael Fay at BCI, Koch Division, Mark Paup, Dave Mellon, and Ray Miller and the Zippo Tool Room. E.E.M.’s contribution to this study was started at the University of Rochester, sponsored by a University Research Award, and was completed at the Jet Propulsion Laboratory, California Institute of Technology, under
a contract with the National Aeronautics and Space Administration. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise, does not constitute or imply its endorsement by the United States Government or the Jet Propulsion Laboratory, California Institute of Technology. This document is approved for unlimited release (CL#17-4355). We thank our anonymous referee for comments that improved this manuscrip
Roles of the pap- and prs-encoded adhesins in Escherichia coli adherence to human uroepithelial cells
Photometric results of the β Pictoris b Hill sphere transit as observed by bRing, ASTEP, BRITE, and the HST
Stars and planetary system