233 research outputs found
Partial nonlinear reciprocity breaking through ultrafast dynamics in a random photonic medium
We demonstrate that ultrafast nonlinear dynamics gives rise to reciprocity
breaking in a random photonic medium. Reciprocity breaking is observed via the
suppression of coherent backscattering, a manifestation of weak localization of
light. The effect is observed in a pump-probe configuration where the pump
induces an ultrafast step-change of the refractive index during the dwell time
of the probe light in the material. The dynamical suppression of coherent
backscattering is reproduced well by a multiple scattering Monte Carlo
simulation. Ultrafast reciprocity breaking provides a distinct mechanism in
nonlinear optical media which opens up avenues for the active manipulation of
mesoscopic transport, random lasers, and photon localization.Comment: 5 pages, 4 figure
Association of television viewing with fasting and 2-h postchallenge plasma glucose levels in adults without diagnosed diabetes
Objectives: To investigate the association between change in daily step count and both adiposity and insulin sensitivity and the extent to which the association between change in daily step count and insulin sensitivity may be mediated by adiposity
Association of change in daily step count over five years with insulin sensitivity and adiposity: population based cohort study
Objectives: To investigate the association between change in daily step count and both adiposity and insulin sensitivity and the extent to which the association between change in daily step count and insulin sensitivity may be mediated by adiposity. Design: Population based cohort study. Setting: Tasmania, Australia. Participants: 592 adults (men (n=267), mean age 51.4 (SD 12.2) years; women (n=325), mean age 50.3 (12.3) years) who participated in the Tasmanian component of the national AusDiab Study in 2000 and 2005. Main outcome measures: Body mass index, waist to hip ratio, and HOMA insulin sensitivity at follow-up in 2005. Results: Over the five year period, the daily step count decreased for 65% (n=382) of participants. Having a higher daily step count in 2005 than in 2000 was independently associated with lower body mass index (0.08 (95% confidence interval 0.04 to 0.12) lower per 1000 steps), lower waist to hip ratio (0.15 (0.07 to 0.23) lower), and greater insulin sensitivity (1.38 (0.14 to 2.63) HOMA units higher) in 2005. The mean increase in HOMA units fell to 0.34 (-0.79 to 1.47) after adjustment for body mass index in 2005. Conclusions: Among community dwelling, middle aged adults, a higher daily step count at five year follow-up than at baseline was associated with better insulin sensitivity. This effect seems to be largely mediated through lower adiposity
Comprehensive High-resolution Chemical Spectroscopy of Barnard's Star with SPIRou
Determination of fundamental parameters of stars impacts all fields of
astrophysics, from galaxy evolution to constraining the internal structure of
exoplanets. This paper presents a detailed spectroscopic analysis of Barnard's
star that compares an exceptionally high-quality (signal-to-noise ratio of
2500 in the band), high-resolution NIR spectrum taken with CFHT/SPIRou
to PHOENIX-ACES stellar atmosphere models. The observed spectrum shows
thousands of lines not identified in the models with a similar large number of
lines present in the model but not in the observed data. We also identify
several other caveats such as continuum mismatch, unresolved contamination and
spectral lines significantly shifted from their expected wavelengths, all of
these can be a source of bias for abundance determination. Out of
observed lines in the NIR that could be used for chemical spectroscopy, we
identify a short list of a few hundred lines that are reliable. We present a
novel method for determining the effective temperature and overall metallicity
of slowly-rotating M dwarfs that uses several groups of lines as opposed to
bulk spectral fitting methods. With this method, we infer = 3231
21 K for Barnard's star, consistent with the value of 3238 11 K
inferred from the interferometric method. We also provide abundance
measurements of 15 different elements for Barnard's star, including the
abundances of four elements (K, O, Y, Th) never reported before for this star.
This work emphasizes the need to improve current atmosphere models to fully
exploit the NIR domain for chemical spectroscopy analysis.Comment: 24 pages, 18 figures, submitted to Ap
Stellar Astrophysics and Exoplanet Science with the Maunakea Spectroscopic Explorer (MSE)
The Maunakea Spectroscopic Explorer (MSE) is a planned 11.25-m aperture
facility with a 1.5 square degree field of view that will be fully dedicated to
multi-object spectroscopy. A rebirth of the 3.6m Canada-France-Hawaii Telescope
on Maunakea, MSE will use 4332 fibers operating at three different resolving
powers (R ~ 2500, 6000, 40000) across a wavelength range of 0.36-1.8mum, with
dynamical fiber positioning that allows fibers to match the exposure times of
individual objects. MSE will enable spectroscopic surveys with unprecedented
scale and sensitivity by collecting millions of spectra per year down to
limiting magnitudes of g ~ 20-24 mag, with a nominal velocity precision of ~100
m/s in high-resolution mode. This white paper describes science cases for
stellar astrophysics and exoplanet science using MSE, including the discovery
and atmospheric characterization of exoplanets and substellar objects, stellar
physics with star clusters, asteroseismology of solar-like oscillators and
opacity-driven pulsators, studies of stellar rotation, activity, and
multiplicity, as well as the chemical characterization of AGB and extremely
metal-poor stars.Comment: 31 pages, 11 figures; To appear as a chapter for the Detailed Science
Case of the Maunakea Spectroscopic Explore
The GeMS/GSAOI Galactic Globular Cluster Survey (G4CS). I. A Pilot Study of the Stellar Populations in NGC 2298 and NGC 3201
We present the first results from the GeMS/GSAOI Galactic Globular Cluster Survey (G4CS) of the Milky Way globular clusters NGC 3201 and NGC 2298. Using the Gemini South Adaptive Optics Imager (GSAOI), in tandem with the Gemini Multi-conjugate adaptive optics System (GeMS) on the 8.1 m Gemini-South telescope, we collected deep near-IR observations of both clusters, resolving their constituent stellar populations down to K s ≃ 21 Vega mag. Point-spread function (PSF) photometry was performed on the data using spatially variable PSFs to generate JHK s photometric catalogs for both clusters. These catalogs were combined with Hubble Space Telescope (HST) data to augment the photometric wavelength coverage, yielding catalogs that span the near-UV to near-IR. We then applied 0.14 mas yr-1 accurate proper-motion cleaning and differential-reddening corrections and chose to anchor our isochrones using the lower main-sequence knee and the main-sequence turnoff prior to age determination. As a result of the data quality, we found that the K s versus F606W - K s and F336W versus F336W - K s color-magnitude diagrams were the most diagnostically powerful. We used these two color combinations to derive the stellar population ages, distances, and reddening values for both clusters. Following isochrone fitting using three different isochrone sets, we derived best-fit absolute ages of 12.2 ±0.5 Gyr and 13.2 ±0.4 Gyr for NGC 3201 and NGC 2298, respectively. This was done using a weighted average over the two aforementioned color combinations, following a pseudo-χ 2 determination of the best-fit isochrone set. Our derived parameters are in good agreement with recent age determinations of the two clusters, with our constraints on the ages being or ranking among the most statistically robust.This research is based on observations obtained at the
Gemini Observatory, which is operated by the Association of
Universities for Research in Astronomy, Inc., under a
cooperative agreement with the NSF on behalf of the Gemini
partnership: the National Science Foundation (United States),
the National Research Council (Canada), CONICYT (Chile),
the Australian Research Council (Australia), Ministério da
Ciência, Tecnologia e Inovação (Brazil) and Ministerio de
Ciencia, and TecnologÃa e Innovación Productiva (Argentina).
Additionally, this research has made use of the NASA/IPAC
Extragalactic Database (NED), which is operated by the Jet
Propulsion Laboratory, California Institute of Technology,
under contract with the National Aeronautics and Space
Administratio
The Maunakea Spectroscopic Explorer Book 2018
(Abridged) This is the Maunakea Spectroscopic Explorer 2018 book. It is
intended as a concise reference guide to all aspects of the scientific and
technical design of MSE, for the international astronomy and engineering
communities, and related agencies. The current version is a status report of
MSE's science goals and their practical implementation, following the System
Conceptual Design Review, held in January 2018. MSE is a planned 10-m class,
wide-field, optical and near-infrared facility, designed to enable
transformative science, while filling a critical missing gap in the emerging
international network of large-scale astronomical facilities. MSE is completely
dedicated to multi-object spectroscopy of samples of between thousands and
millions of astrophysical objects. It will lead the world in this arena, due to
its unique design capabilities: it will boast a large (11.25 m) aperture and
wide (1.52 sq. degree) field of view; it will have the capabilities to observe
at a wide range of spectral resolutions, from R2500 to R40,000, with massive
multiplexing (4332 spectra per exposure, with all spectral resolutions
available at all times), and an on-target observing efficiency of more than
80%. MSE will unveil the composition and dynamics of the faint Universe and is
designed to excel at precision studies of faint astrophysical phenomena. It
will also provide critical follow-up for multi-wavelength imaging surveys, such
as those of the Large Synoptic Survey Telescope, Gaia, Euclid, the Wide Field
Infrared Survey Telescope, the Square Kilometre Array, and the Next Generation
Very Large Array.Comment: 5 chapters, 160 pages, 107 figure
Crop Updates 2003 - Geraldton
This session covers twenty eight papers from different authors
Seasonal Outlook: What is in store for 2003, David Stephens, Department of Agriculture
Examining The Management Options For Wheat Crops In The Coming Season, James Fisher, Department of Agriculture
GMO’s – what do they offer? Ian Edwards, Grain Bio Tech Australia Pty Ltd
The Big Gamble – Wheat prices for 2003, Dennis Wise, Profarmer
Market outlook for other grains, Andrew Young, General Manager Agricorp
Stripe rust – where to now for the WA wheat industry? Robert Loughman, Ciara Beard and Greg Shea, Department of Agriculture
Baudin and Hamlin – new generation of malting barley developed in Western Australia, Blakely Paynter, Roslyn Jettner and Kevin Young, Department of Agriculture
DBM in Canola, Kevin Walden, Department of Agriculture
The latest on Lupin diseases, Geoff Thomas, Department of Agriculture
Wheat variety performance in 2002 compared to the long term, Robin Wilson, Iain Barclay, Robyn McLean, Robert Loughman, Jenny Garlinge, Bill Lambe, Neil Venn and Peter Clarke, Department of Agriculture
Do wide rows drought proof lupins on red loam? Martin Harries, Bob French, Wayne Parker and Murray Blyth, Department of Agriculture
Do wide rows drought proof lupins on a sandy loam? Martin Harries, Bob French, Wayne Parker and Murray Blyth, Department of Agriculture
Profit Proving Precision Agriculture, Peter Norris, Agronomy For Profit, Greg Lyle, CSIRO Land and Water, Yuna Farm Improvement Group
Annual ryegrass seedbanks: the good, the bad, and the ugly, Kathryn Steadman, University of Western Australia, Amander Ellery, CSIRO Plant Industry, Sally C Peltzer, Department of Agriculture
Wheat management packages for low rainfall areas, Kari-Lee Falconer, Department of Agriculture
Ground water 1. Atrazine, Russell Speed, Department of Agriculture
Groundwater 2. Current Trends, Russell Speed, Department of Agriculture
Herbicide tolerance of wheat, lupins and pastures, Terry Piper and Harmohinder Dhammu, Department of Agriculture
Farming with Tramlines, Bindi Webb, Paul Blackwell, Department of Agriculture, Phil Logue, Binnu, Nigel Moffat, Geraldton, Rohan Ford, Binnu, Miles Obst, Mingenew,
The role of green manure crops in renovating poor performing paddocks: What’s it worth? Frances Hoyle, Leanne Schulz and Judith Devenish Department of Agriculture
The looming threat of wild radish, Peter Newman, Department of Agriculture
Does one ‘size’ fit all? Grant Morrow, Syngenta Crop Protection
Climate Forecasts on the Internet, Ian Foster and David Stephens, Department of Agriculture
Moisture delving = more reliable lupin establishment, Paul Blackwell, and Wayne Parker, Department of Agriculture
Tramline Designs for better Weed control and Wheat value from non-spraying tramlines in a dry season, Paul Blackwell, Bindi Webb and Darshan Sharma, Department of Agriculture
Biserrula Grazing Trial, Marnie Thomas, Department of Agriculture
Performance of IT and TT canola varieties in the medium and high rainfall agzones of W.A., 2001-02, Graham Walton, Hasan Zaheer and Paul Carmody, Department of Agriculture
Rapid Catchment Appraisal in Northern Agricultural Region, Mike Clarke, Paul Raper, Department of Agricultur
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