4,693 research outputs found
Exoplanet Transmission Spectroscopy using KMOS
KMOS (K-Band Multi Object Spectrograph) is a novel integral field
spectrograph installed in the VLT's ANTU unit. The instrument offers an ability
to observe 24 2.8"2.8" sub-fields positionable within a 7.2' patrol
field, each sub-field producing a spectrum with a 1414-pixel spatial
resolution. The main science drivers for KMOS are the study of galaxies, star
formation, and molecular clouds, but its ability to simultaneously measure
spectra of multiple stars makes KMOS an interesting instrument for exoplanet
atmosphere characterization via transmission spectroscopy. We set to test
whether transmission spectroscopy is practical with KMOS, and what are the
conditions required to achieve the photometric precision needed, based on
observations of a partial transit of WASP-19b, and full transits of GJ 1214b
and HD 209458b. Our analysis uses the simultaneously observed comparison stars
to reduce the effects from instrumental and atmospheric sources, and Gaussian
processes to model the residual systematics. We show that KMOS can, in theory,
deliver the photometric precision required for transmission spectroscopy.
However, this is shown to require a) pre-imaging to ensure accurate centering
and b) a very stable night with optimal observing conditions (seeing
0.8"). Combining these two factors with the need to observe several
transits, each with a sufficient out-of-transit baseline (and with the fact
that similar or better precision can be reached with telescopes and instruments
with smaller pressure,) we conclude that transmission spectroscopy is not the
optimal science case to take advantage of the abilities offered by KMOS and
VLT.Comment: 11 pages, accepted to MNRA
Expanding known dinoflagellate distributions : investigations of slurry cultures from Caspian Sea sediment
To investigate the disparity between plankton and cyst records, sediment slurry cultures were used to isolate the motile stage of dinoflagellates from Caspian Sea sediment. This has resulted in new records for this area of Kryptoperidinium foliaceum, Gymnodinium aureolum and Woloszynskia sp. and for the cyst record, Scrippsiella acuminata. Two Gonyaulax species were isolated, one was identified as Gonyaulax baltica and the other an unknown species. Cultures of Lingulodinium polyedra were also isolated. The approach of using slurries was useful to provide cultures from sediments that were relatively poor in dinoflagellate cysts with contents
Evaluation of the Water Footprint of Beef Cattle Production in Nebraska
Data were compiled on feed usage to model the amount of water needed to produce beef in typical Nebraska production systems. Production systems where cows were wintered on corn residue utilized 18% less water than systems utilizing native range as a wintering source, because of water allocations. Therefore, the water footprint (gallons of water required to produce one pound of boneless meat) was decreased by 18%. In addition, increasing the dietary inclusion of distillers grains from 0% to 40% decreased the water footprint in the finishing phase by 29%, again based on water allocation. Utilizing corn residue and distillers grains in Nebraska beef cattle systems decreases the overall water footprint of production. Additionally, the water footprint of the systems analyzed was 80% green water as rain, minimizing the environmental impact of beef production on freshwater use and ecological water balance
A uniform analysis of HD209458b Spitzer/IRAC lightcurves with Gaussian process models
We present an analysis of Spitzer/IRAC primary transit and secondary eclipse
lightcurves measured for HD209458b, using Gaussian process models to
marginalise over the intrapixel sensitivity variations in the 3.6 micron and
4.5 micron channels and the ramp effect in the 5.8 micron and 8.0 micron
channels. The main advantage of this approach is that we can account for a
broad range of degeneracies between the planet signal and systematics without
actually having to specify a deterministic functional form for the latter. Our
results do not confirm a previous claim of water absorption in transmission.
Instead, our results are more consistent with a featureless transmission
spectrum, possibly due to a cloud deck obscuring molecular absorption bands.
For the emission data, our values are not consistent with the thermal inversion
in the dayside atmosphere that was originally inferred from these data.
Instead, we agree with another re-analysis of these same data, which concluded
a non-inverted atmosphere provides a better fit. We find that a solar-abundance
clear-atmosphere model without a thermal inversion underpredicts the measured
emission in the 4.5 micron channel, which may suggest the atmosphere is
depleted in carbon monoxide. An acceptable fit to the emission data can be
achieved by assuming that the planet radiates as an isothermal blackbody with a
temperature of K.Comment: 18 pages, 5 figures, 6 tables. Accepted by MNRA
Hazards, Culture and Indigenous Communities: Final Project Report
This is the Final Report of the Hazards, Culture and Indigenous Communities (HCIC) project. This project considered the challenges and opportunities arising out of engagements between Indigenous peoples and natural hazard and land management government agencies in southern Australia. The majority of this activity has focused on cultural burning, which has also been our focus. Significantly, there is very limited existing research about these engagements, and limited public sector experience in engaging with Indigenous peoples. This constrains evidenced-based policy and practice and practitioner decision making. This lack of capacity was clear in the responses to the 2019-20 bushfires. The natural hazard sector is now required to do this retrospective and forward-looking learning, to foster more culturally safe natural hazard mitigation, and better connect the logics of hazards, risk and resilience. We undertook qualitative research, primarily through forming partnerships with key practitioners working in this space and undertaking research activities that iteratively learnt from these partnerships. In this, researching both Indigenous and non-indigenous values has been important in order to navigate and analyse this intercultural context. Our research findings are structured in two sections: the first presents the results from our literature review, the second presents a synthesis of the research findings arranged under six headings, as listed below, with recommended first steps for the natural hazard sector under each heading. Given previous sector and research practices, the suggested first steps require significant sector leadership and investment in Indigenous-led research
Scientific Diversity, Scientific Uncertainty and Risk Mitigation Policy & Planning: Final Report
This is the Final Report of the ‘RMPP project’ (Scientific Diversity, Scientific Uncertainty and Risk Mitigation Policy and Planning project), which addressed the use and utility of science and other forms of knowledge by natural hazard practitioners, and the pragmatic meaning these hold for their risk mitigation work. Natural hazard managers often expect, and are expected, to achieve outcomes by using scientific facts and rational problem-solving to increase certainty of decisions in the face of hazardous events (Funtowitcz and Ravetz, 2003). At the same time, the uncertainties of natural hazards means that this sector has always set different terms to the this ‘pipeline’ approach to the use science (also called the ‘linear model of scientific expertise’). The ability of policymakers and practitioners to explain and justify risk mitigation and its evidence is compromised without greater insight into how science and other forms of knowledge are used in emergency management policy and practice. The sector does not receive the full range of information it requires, and continues to be vulnerable to the perpetuation of ‘myths’ about science, its use and its usefulness. Instead of relying on facts to generate better policy and practices, as invaluable as they are, we ask: what are ‘facts’, how do facts, values and action interrelate, and what are the implications of these insights to allow practitioners to make better decisions? Two literature reviews were conducted, the first examined the use of scenario methods for environmental risk, and the second identified the types of scientific uncertainties in flood and bushfire science. These uncertainties were then organised into three categories: historicist, reliance on historical data, due to assumed determining relationship between the past, the present and the future; instrumental, uncertainty arising out of limitations of a given apparatus, heuristic or theory, and interventionist, are those uncertainties in the predictive calculations about the effect of mitigation interventions (e.g. flood levy banks). Three case studies were conducted, each located in an important risk landscapes in which scientific knowledge was being used to change policy and/or practice and address a complex emergency management problem: Wildfire risk and prescribed burning, in the Barwon-Otway region, Victoria; Wildfire risk and an invasive fire-weed, in the Greater Darwin area, Northern Territory; and, Flood risk and mitigation planning in the Hawkesbury-Nepean Valley, New South Wales
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