1,357 research outputs found
The ALMaQUEST survey – III. Scatter in the resolved star-forming main sequence is primarily due to variations in star formation efficiency
Using a sample of 11,478 spaxels in 34 galaxies with molecular gas, star formation and stellar maps taken from the ALMA-MaNGA QUEnching and STar formation (ALMaQUEST) survey, we investigate the parameters that correlate with variations in star formation rates on kpc scales. We use a combination of correlation statistics and an artificial neural network to quantify the parameters that drive both the absolute star formation rate surface density (Sigma_SFR), as well as its scatter around the resolved star forming main sequence (Delta Sigma_SFR). We find that Sigma_SFR is primarily regulated by molecular gas surface density (Sigma_H2) with a secondary dependence on stellar mass surface density (Sigma_*), as expected from an `extended Kennicutt-Schmidt relation'. However, Delta Sigma_SFR is driven primarily by changes in star formation efficiency (SFE), with variations in gas fraction playing a secondary role. Taken together, our results demonstrate that whilst the absolute rate of star formation is primarily set by the amount of molecular gas, the variation of star formation rate above and below the resolved star forming main sequence (on kpc scales) is primarily due to changes in SFE
Nitrogen Fertilizer and Irrigation Effects on Seed Yield and Oil in Camelina
Interest is growing in camelina (Camelina sativa L. Crantz) as a biofuel feedstock. However, there has been little camelina research in irrigated arid systems. A 2-yr field study in Maricopa, AZ, under an overhead sprinkler irrigation system determined the effects of 10 water levels (irrigation fraction 0.5–1.1) and five N fertilizer rates (38–150 kg N ha–1) on seed yield, seed oil content, and N use efficiency. Cultivar Robinson was planted in December 2012 and 2013. Nitrogen fertilizer (urea ammonium nitrate) was applied in three split applications. Irrigation amounts were from 125 to 380 mm, and in-season rain was 70 and 50 mm, in 2013 and 2014, respectively. Camelina seed yields were maximum at water level 7 (irrigation fraction 0.93) in 2013 at 1800 kg ha–1. Maximum seed yields were 1600 kg ha–1 at water level 6 (irrigation fraction 0.83) in 2014. These highest seed yields were achieved with 150 kg N ha–1 in both years. Oil content (maximum 41%) decreased with N rate but increased with water level. Seed N increased with N rate but decreased with irrigation level. Recovery efficiency of N fertilizer by camelina ranged from 12 to 72%. The results indicate that good high-oil camelina yields can be produced in the southwestern United States with 320 to 380 mm irrigation plus rain and N fertilizer rates of 150 kg N ha–1
The Relationship of Competitive Athletics to the Secondary Education Program
It was the purpose of this research to review the literature concerning the attitudes toward competitive athletics in our secondary schools. Educators have long recognized the need for a better administrative program of competitive athletics in the secondary education system. The questions that confront them are: Do competitive athletics have a place in our secondary school program? Do they offer the opportunity for high school youth to work toward or obtain worthwhile individual or cultural goals? In this paper the writer will attempt to find answers to these questions
Tris-N-alkylpyridinium-functionalised cyclotriguaiacylene hosts as axles in branched [4]pseudorotaxane formation
A series of [4]pseudorotaxanes composed of three-way axle threads based on the cyclotriguaiacylene family of crown-shaped cavitands and three threaded macrocyclic components has been achieved. These exploit the strong affinity for electron-poor alkyl-pyridinium units to reside within the electron-rich cavity of macrocycles, in this case dimethoxypillar[5]arene (DMP). The branched [4]pseudorotaxane= assemblies {(DMP)3∙L}3+,where L = N-alkylated derivatives of the host molecule (±)-tris-(isonicotinoyl)cyclotriguaiacylene, were characterised by NMR spectroscopy and mass spectrometry, and an energy-minimised structure of {(DMP)3∙(tris-(N-propyl-isonicotinoyl)cyclotriguaiacylene)}3+ was calculated. Crystal structures of N-ethyl-isonicotinoyl)cyclotriguaiacylene hexafluorophosphate and N-propyl-isonicotinoyl)cyclotriguaiacylene hexafluorophosphate each show ‘hand-shake’ self-inclusion motifs occurring between the individual cavitands
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Using scenarios to explore UK upland futures
Uplands around the world are facing significant social, economic and environmental changes, and decision-makers need to better understand what the future may hold if they are to adapt and maintain upland goods and services. This paper draws together all major research comprising eight studies that have used scenarios to describe possible futures for UK uplands. The paper evaluates which scenarios are perceived by stakeholders to be most likely and desirable, and assesses the benefits and drawbacks of the scenario methods used in UK uplands to date. Stakeholders agreed that the most desirable and likely scenario would be a continuation of hill farming (albeit at reduced levels) based on cross-compliance with environmental measures. The least desirable scenario is a withdrawal of government financial support for hill farming. Although this was deemed by stakeholders to be the least likely scenario, the loss of government support warrants close attention due to its potential implications for the local economy. Stakeholders noted that the environmental implications of this scenario are much less clear-cut. As such, there is an urgent need to understand the full implications of this scenario, so that upland stakeholders can adequately prepare, and policy-makers can better evaluate the likely implications of different policy options. The paper concludes that in future, upland scenario research needs to: (1) better integrate in-depth and representative participation from stakeholders during both scenario development and evaluation; and (2) make more effective use of visualisation techniques and simulation models
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The ALMaQUEST survey IX: The nature of the resolved star forming main sequence
We investigate the nature of the scaling relations between the surface
density of star formation rate (), stellar mass (), and molecular gas mass (), aiming at distinguishing
between the relations that are primary, i.e. more fundamental, and those which
are instead an indirect by-product of the other relations. We use the ALMaQUEST
survey and analyse the data by using both partial correlations and Random
Forest regression techniques. We unambiguously find that the strongest
intrinsic correlation is between and
(i.e. the resolved Schmidt-Kennicutt relation), followed by the correlation
between and (resolved Molecular Gas Main
Sequence, rMGMS). Once these two correlations are taken into account, we find
that there is no evidence for any intrinsic correlation between and , implying that SFR is entirely driven by the amount of
molecular gas, while its dependence on stellar mass (i.e. the resolved Star
Forming Main Sequence, rSFMS) simply emerges as a consequence of the
relationship between molecular gas and stellar mass.Science and Technology Facilities Council (STFC).
ERC Advanced Grant 695671 "QUENCH"
The ALMaQUEST Survey: VI. The molecular gas main sequence of `retired' regions in galaxies
In order to investigate the role of gas in the demise of star formation on
kpc-scales, we compare the resolved molecular gas main sequence (rMGMS: Sigma_*
vs Sigma_H2) of star-forming regions to the sequence of `retired' regions that
have ceased to form new stars. Using data from the ALMaQUEST survey, we find
that retired spaxels form a rMGMS that is distinct from that of star-forming
spaxels, offset to lower Sigma_H2 at fixed Sigma_* by a factor of ~5. We study
the rMGMS of star-forming and retired spaxels on a galaxy-by-galaxy basis for
eight individual ALMaQUEST galaxies. Six of these galaxies have their retired
spaxels concentrated within the central few kpc. Molecular gas is detected in
40-100% of retired spaxels in the eight galaxies in our sample. Both the
star-forming and retired rMGMS show a diversity in normalization from
galaxy-to-galaxy. However, in any given galaxy, the rMGMS for retired regions
is found to be distinct from the star-forming sequence and gas fractions of
retired spaxels are up to an order of magnitude lower than the star-forming
spaxels. We conclude that quenching is associated with a depletion (but not
absence) of molecular gas via a mechanism that typically begins in the centre
of the galaxy.Comment: MNRAS, in pres
Dairy Farm Business Summary: Western and Central Plain Region 1995
E.B. 96-06Dairy farmers throughout New York State have been participating in Cornell Cooperative Extension's farm business summary and analysis program since the early 1950's. Managers of each participating farm business receive a comprehensive summary and analysis of the farm business. The information in this report represents an average of the data submitted from dairy farms in the Western and Central Plain Region for 1995
The time resolution of the St. Petersburg paradox
A resolution of the St. Petersburg paradox is presented. In contrast to the
standard resolution, utility is not required. Instead, the time-average
performance of the lottery is computed. The final result can be phrased
mathematically identically to Daniel Bernoulli's resolution, which uses
logarithmic utility, but is derived using a conceptually different argument.
The advantage of the time resolution is the elimination of arbitrary utility
functions.Comment: 20 pages, 1 figur
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