222 research outputs found
Assessment and deployment of bird-carried meteorological sensors for microclimate measurements in urban terrain
Wide-Band/Dual-Band Packaged Antenna for 5-6 GHz WLAN Application
A wide-band/dual-band packaged antenna is proposed for wireless local-area network (WLAN) applications in the 5.15-5.35 GHz and 5.725-5.825 GHz frequency range. The antenna is internal to the housing of a personal digital assistant, such as a Palm organizer, and has the dimensions of 28 by 9 by 3 ram on an FR4 substrate. The antenna meets or exceeds the bandwidth requirements for the dual-band IEEE 802.11a WLAN applications (5.15-5.35 GHz and 5.725-5.825 GHz) within 2:1 voltage standing-wave ratio
The extragalactic radio-source population at 95 GHz
We have used the Australia Telescope Compact Array (ATCA) at 95GHz to carry
out continuum observations of 130 extragalactic radio sources selected from the
Australia Telescope 20GHz (AT20G) survey. Over 90% of these sources are
detected at 95 GHz, and we use a triple-correlation method to measure
simultaneous 20 and 95 GHz flux densities. We show that the ATCA can measure
95GHz flux densities to ~10% accuracy in a few minutes for sources above
~50mJy.
The median 20-95GHz spectral index does not vary significantly with flux
density for extragalactic sources with S20>150 mJy. This allows us to estimate
the extragalactic radio source counts at 95GHz by combining our observed
20-95GHz spectral-index distribution with the accurate 20GHz source counts
measured in the AT20G survey. The resulting 95GHz source counts down to 80 mJy
are significantly lower than those found by several previous studies. The main
reason is that most radio sources with flat or rising spectra in the frequency
range 5-20GHz show a spectral turnover between 20 and 95 GHz. As a result,
there are fewer 95GHz sources (by almost a factor of two at 0.1 Jy) than would
be predicted on the basis of extrapolation from the source populations seen in
lower-frequency surveys. We also derive the predicted confusion noise in CMB
surveys at 95GHz and find a value 20-30% lower than previous estimates.
The 95GHz source population at the flux levels probed by this study is
dominated by QSOs with a median redshift z~1. We find a correlation between
optical magnitude and 95GHz flux density which suggests that many of the
brightest 95 GHz sources are relativistically beamed, with both the optical and
millimetre continuum significantly brightened by Doppler boosting.Comment: Replaced with final version (MNRAS, in press), 15 pages plus two
landscape data table
Secondary Science and Mathematics Teachers’ Environmental Issues Engagement through SocioScientific Reasoning
Among the many responsibilities of K-12 educators is to promote the development of environmental literacy among their students. Contentious environmental issues are often considered socioscientific issues (SSI; e.g., climate change) in that they are rooted in science, but a myriad of non-scientific (e.g., cultural, political, economic, etc.) factors must be addressed if those issues are to be successfully resolved. Teachers often report being ill-equipped to address these non-scientific factors, which may be due to struggles with employing socioscientific reasoning (SSR). SSR includes understanding the complexity of SSI, engaging in perspective-taking and ongoing inquiry about SSI, employing skepticism when dealing with potentially biased information concerning SSI, and recognizing the affordances of science and non-science considerations in resolving those issues. In this study, mathematics and science teachers who engaged in an SSI-oriented professional development demonstrated a range of sophistication across the dimensions of SSR, with science teachers tending to exhibit more sophistication in their SSR than mathematics teachers. Herein, we share and discuss the results of the study, including the prompts and scoring rubrics with exemplars, which can be used to prepare teachers to teach about contentious SSI and enable them to more effectively instruct and evaluate their students when doing so
Fruit softening:Evidence for pectate lyase action in vivo in date (Phoenix dactylifera) and rosaceous fruit cell walls
Environmental Implications of Increased Bioenergy Production on Midwest Soil Landscapes [abstract]
Only abstract of poster available.Track III: Energy InfrastructurePrairie soil landscapes encompass over 16 million acres in Missouri and surrounding states. Much of this area has been degraded by erosion but is still used for grain production. Erosion has caused variable topsoil depth within fields which in turn has resulted in greater within-field variability of crop yield, magnified the drought-prone nature of these soils, and lowered the overall soil productivity and ecosystem function. In recent years, pressure on these sensitive soils has risen due to higher demand for grain production, in part for ethanol and biodiesel. In some areas, highly erodible fields which were historically managed as CRP and pasture are being turned into grain crop acres. Thus as new and fluctuating feed and bioenergy markets develop, land management practices will also shift, resulting in changes in soil and water quality of watersheds. This presentation will explore the likely environmental implications of different types of bioenergy production on the soil resource. Further, the positive benefits of potential changes in land use will be in explored. For example, one alternative for sensitive soils is production of perennial grass as a feedstock for coal co-burning plants and for potential future use in cellulosic ethanol production. Perennial grass yields are likely to be less variable than grain yields, both year-to-year and within fields, primarily because of greater resistance to drought. Grass production systems also provide environmental services not obtained from annual grain crops. We will also discuss our work on developing ways to target the most appropriate places in the landscape for grain or perennial production so as to enhance ecosystem services and improve soil and water quality
The properties of extragalactic radio sources selected at 20 GHz
We present some first results on the variability, polarization and general
properties of radio sources selected in a blind survey at 20 GHz, the highest
frequency at which a sensitive radio survey has been carried out over a large
area of sky. Sources with flux densities above 100 mJy in the AT20G Pilot
Survey at declination -60 to -70 were observed at up to three epochs during
2002-4, including near-simultaneous measurements at 5, 8 and 18 GHz in 2003. Of
the 173 sources detected, 65% are candidate QSOs, BL Lac objects or blazars,
20% galaxies and 15% faint (b > 22 mag) optical objects or blank fields.
On a 1-2 year timescale, the general level of variability at 20 GHz appears
to be low. For the 108 sources with good-quality measurements in both 2003 and
2004, the median variability index at 20 GHz was 6.9% and only five sources
varied by more than 30% in flux density.
Most sources in our sample show low levels of linear polarization (typically
1-5%), with a median fractional polarization of 2.3% at 20 GHz. There is a
trend for fainter sources to show higher fractional polarization.
At least 40% of sources selected at 20GHz have strong spectral curvature over
the frequency range 1-20 GHz. We use a radio `two-colour diagram' to
characterize the radio spectra of our sample, and confirm that the radio-source
population at 20 GHz (which is also the foreground point-source population for
CMB anisotropy experiments like WMAP and Planck) cannot be reliably predicted
by extrapolating the results of surveys at lower frequencies. As a result,
direct selection at 20 GHz appears to be a more efficient way of identifying 90
GHz phase calibrators for ALMA than the currently-proposed technique of
extrapolation from all-sky surveys at 1-5 GHz.Comment: 14-page paper plus 5-page data table. Replaced with published versio
Elevated CO2 does not improve seedling performance in a naturally regenerated oak woodland exposed to biotic stressors
The Effect of Hoof Abnormalities on Sow Behavior Before and After Feeding When Housed in a Farrowing Stall
The objective of this study was to evaluate the effects of excessive toe growth, hoof cracks in the outer hoof wall, and length difference between the inside and outside toe of the hoof on sow behavior in mid-lactation. Sows were classified into three treatment groups and one control group. The treatment groups were 1) presence of cracks in the outer hoof wall 2) length differences between the inside and outer toe of the hoof and 3) excessive toe growth. Some sows had both toe size differences and cracks in the outer hoof wall (n = 23). Hoof abnormalities were categorized into 3 scores based on the severity of the lesion. Control sows spent 12.7 % (13.3 min) of the total time (105 min) standing and eating. Before feeding, control sows spent 1.2 % of time standing and eating Sows with overgrown hooves spent less time standing and eating as lesion severity increased when compared to control sows. Each increase in overgrown hoof lesion score was associated with sows spending 54 % less time standing Sows classified as having hoof cracks were observed to stand more and lay down less than control sows; however, this may have resulted from the inability to identify hoof lesions that caused pain. As a result, sows with hoof lesions that did not have pain were grouped with sows that had hoof lesions that caused pain and may have reduced the true effect of hoof lesions on behavior. In this study, sows that had differences in toe size were not associated with a deviation from the control sows
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