899 research outputs found
Precision Agriculture: Yield Monitors (1998)
Yield monitors are an essential component of many site-specific management strategies. Yield maps, the visual and numerical product of yield monitors, encourage creative investigation and can provide reliable answers to carefully performed on-farm experiments. Yield maps provide feedback for determining the effects of managed inputs such as fertilizer and lime, seed and pesticides, and cultural practices such as tillage, irrigation and drainage
Dimming the Lights: 2D Simulations of Deflagrations of Hybrid C/O/Ne White Dwarfs using FLASH
The dimmest and most numerous outlier of the Type Ia supernova population,
Type Iax events, is increasingly being found in the results of observational
campaigns. There is currently no single accepted model to describe these
events. This 2D study explores the viability of modeling Type Iax events as a
hybrid C/O/Ne white dwarf progenitor undergoing a deflagration using the
multi-physics software FLASH. This hybrid was created using the stellar
evolution code MESA, and its C-depleted core and mixed structure have
demonstrated lower yields than traditional C/O progenitors in previous
deflagration-to-detonation studies. To generate a sample, 30 "realizations" of
this simulation were performed, the only difference being the shape of the
initial matchhead used to start the deflagration. As consistent with earlier
work, these realizations produce the familiar hot dense bound remnant
surrounded by sparse ejecta. Our results indicate the majority of the star
remains unburned (~70%) and bound (>90%). Our realizations produce total ejecta
yields on the order of 10 - 10 solar masses, ejected Ni
yields on the order of 10 - 10 solar masses, and ejecta kinetic
energies on the order of 10 - 10 ergs. Compared to yields
inferred from recent observations of the dimmest Type Iax events - SN 2007qd,
SN 2008ha, SN 2010ae, SN 2019gsc, SN 2019muj, SN 2020kyg, and SN 2021fcg - our
simulation produces comparable Ni yields, but too-small total yields and
kinetic energies. Reignition of the remnant is also seen in some realizations.Comment: 43 pages, 15 figures, 4 tables. To be published in Ap
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Status of the solar and infrared radiation submodels in the LLNL 1-D and 2-D chemical-transport models
The authors have implemented a series of state of the art radiation transport submodels in previously developed one dimensional and two dimensional chemical transport models of the troposphere and stratosphere. These submodels provide the capability of calculating accurate solar and infrared heating rates. They are a firm basis for further radiation submodel development as well as for studying interactions between radiation and model dynamics under varying conditions of clear sky, clouds, and aerosols. 37 refs., 3 figs
Association of asthma symptoms with peak particulate air pollution and effect modification by anti-inflammatory medication use.
Maxima of hourly data from outdoor monitors may capture adverse effects of outdoor particulate matter (PM) exposures in asthmatic children better than do 24-hr PM averages, which form the basis of current regulations in the United States. Also, asthmatic children on anti-inflammatory medications may be protected against the proinflammatory effects of air pollutants and aeroallergens. We examined strengths of pollutant associations with asthma symptoms between subgroups of asthmatic children who were on versus not on regularly scheduled anti-inflammatory medications, and tested associations for different particle averaging times. This is a daily panel study of 22 asthmatic children (9-19 years of age) followed March through April 1996 (1,248 person-days). They lived in nonsmoking households in a semirural area of Southern California within the air inversion mixing zone (range, 1,200-2,100 feet) with transported air pollution from urban areas of Southern California. The dependent variable derived from diary ordinal scores is episodes of asthma symptoms that interfered with daily activities. Minimum to 90th-percentile levels of exposures at the outdoor monitoring site were 12-63 microg/m(3) for 1-hr PM < 10 microm in aerodynamic diameter (PM(10)); 8-46 microg/m(3) for 8-hr PM(10); 7-32 microg/m(3) for 24-hr PM(10); 45-88 ppb for 1-hr O(3); 6-26 ppb for 8-hr NO(2); 70-4,714 particles/m(3) for 12-hr daytime fungi; and 12-744 particles/m(3) for 24-hr pollen. Data were analyzed with generalized estimating equations controlling for autocorrelation. There was no confounding by weather, day of week, or linear time trend. Associations were notably stronger in 12 asthmatic children who were not taking anti-inflammatory medications versus 10 subjects who were. Odds ratios (95% confidence intervals) for asthma episodes in relation to lag 0 minimum to 90th-percentile pollutant changes were, respectively, 1-hr maximum PM(10), 1.92 (1.22-3.02) versus 0.96 (0.25-3.69); 8-hr maximum PM(10), 1.68 (0.91-3.09) versus 0.75 (0.18-3.04); 24-hr average PM(10), 1.35 (0.82-2.22) versus 0.80 (0.24-2.69); 1-hr maximum O(3), 1.28 (0.75-2.17) versus 0.76 (0.24-2.44); 8-hr maximum NO(2), 1.91 (1.07-3.39) versus 1.08 (0.30-3.93); 12-hr fungi, 1.89 (1.24-2.89) versus 0.90 (0.35-2.30); 24-hr pollen, 1.90 (0.99-3.67) versus 0.85 (0.18-3.91). Pollutant associations were stronger during respiratory infections in subjects not on anti-inflammatory medications. Although lag 0 1-hr maximum PM(10) showed the strongest association, the most robust associations were for lag 0 and 3-day moving averages (lags 0-2) of 8-hr maximum and 24-hr mean PM(10) in sensitivity analyses testing for thresholds. Most pollutant effects were largely driven by concentrations in the upper quintile. The divergence of exposure-response relationships by anti-inflammatory medication use is consistent with experimental data on inflammatory mechanisms of airborne pollutants and allergens
Seeing the way: visual sociology and the distance runner's perspective
Employing visual and autoethnographic data from a two‐year research project on distance runners, this article seeks to examine the activity of seeing in relation to the activity of distance running. One of its methodological aims is to develop the linkage between visual and autoethnographic data in combining an observation‐based narrative and sociological analysis with photographs. This combination aims to convey to the reader not only some of the specific subcultural knowledge and particular ways of seeing, but also something of the runner's embodied feelings and experience of momentum en route. Via the combination of narrative and photographs we seek a more effective way of communicating just how distance runners see and experience their training terrain. The importance of subjecting mundane everyday practices to detailed sociological analysis has been highlighted by many sociologists, including those of an ethnomethodological perspective. Indeed, without the competence of social actors in accomplishing these mundane, routine understandings and practices, it is argued, there would in fact be no social order
Relativistic conservation laws and integral constraints for large cosmological perturbations
For every mapping of a perturbed spacetime onto a background and with any
vector field we construct a conserved covariant vector density ,
which is the divergence of a covariant antisymmetric tensor density, a
"superpotential". is linear in the energy-momentum tensor
perturbations of matter, which may be large; does not contain the
second order derivatives of the perturbed metric. The superpotential is
identically zero when perturbations are absent.
By integrating conserved vectors over a part \Si of a hypersurface of
the background, which spans a two-surface \di\Si, we obtain integral
relations between, on the one hand, initial data of the perturbed metric
components and the energy-momentum perturbations on \Si and, on the other
hand, the boundary values on \di\Si. We show that there are as many such
integral relations as there are different mappings, 's, \Si's and
\di\Si's. For given boundary values on \di\Si, the integral relations may
be interpreted as integral constraints (e.g., those of Traschen) on local
initial data including the energy-momentum perturbations. Conservation laws
expressed in terms of Killing fields \Bar\xi of the background become
"physical" conservation laws.
In cosmology, to each mapping of the time axis of a Robertson-Walker space on
a de Sitter space with the same spatial topology there correspond ten
conservation laws. The conformal mapping leads to a straightforward
generalization of conservation laws in flat spacetimes. Other mappings are also
considered. ...Comment: This paper, published 7 years ago, was found useful by some
researchers but originally was not put on the gr-qc website. Now it has been
retyped with very minor changes: few wordings have been modified and several
misprints occurring in the printed version correcte
Financing Direct Democracy: Revisiting the Research on Campaign Spending and Citizen Initiatives
The conventional view in the direct democracy literature is that spending against a measure is more effective than spending in favor of a measure, but the empirical results underlying this conclusion have been questioned by recent research. We argue that the conventional finding is driven by the endogenous nature of campaign spending: initiative proponents spend more when their ballot measure is likely to fail. We address this endogeneity by using an instrumental variables approach to analyze a comprehensive dataset of ballot propositions in California from 1976 to 2004. We find that both support and opposition spending on citizen initiatives have strong, statistically significant, and countervailing effects. We confirm this finding by looking at time series data from early polling on a subset of these measures. Both analyses show that spending in favor of citizen initiatives substantially increases their chances of passage, just as opposition spending decreases this likelihood
Cognitive Information Processing
Contains research objectives and summary of research on fourteen research projects and reports on four research projects.Joint Services Electronics Program (Contract DAAB07-75-C-1346)National Science Foundation (Grant EPP74-12653)National Science Foundation (Grant ENG74-24344)National Institutes of Health (Grant 2 PO1 GM19428-04)Swiss National Funds for Scientific ResearchM.I.T. Health Sciences Fund (Grant 76-11)National Institutes of Health (Grant F03 GM58698)National Institutes of Health (Biomedical Sciences Support Grant)Associated Press (Grant
Anatomy of a post-starburst minor merger: a multi-wavelength WFC3 study of NGC 4150
(Abridged) We present a spatially-resolved near-UV/optical study of NGC 4150,
using the Wide Field Camera 3 (WFC3) on board the Hubble Space Telescope.
Previous studies of this early-type galaxy (ETG) indicate that it has a large
reservoir of molecular gas, exhibits a kinematically decoupled core (likely
indication of recent merging) and strong, central H_B absorption (indicative of
young stars). The core of NGC 4150 shows ubiquitous near-UV emission and
remarkable dusty substructure. Our analysis shows this galaxy to lie in the
near-UV green valley, and its pixel-by-pixel photometry exhibits a narrow range
of near-UV/optical colours that are similar to those of nearby E+A
(post-starburst) galaxies. We parametrise the properties of the recent star
formation (age, mass fraction, metallicity and internal dust content) in the
NGC 4150 pixels by comparing the observed near-UV/optical photometry to stellar
models. The typical age of the recent star formation (RSF) is around 0.9 Gyrs,
consistent with the similarity of the near-UV colours to post-starburst
systems, while the morphological structure of the young component supports the
proposed merger scenario. The RSF metallicity, representative of the
metallicity of the gas fuelling star formation, is around 0.3 - 0.5 Zsun.
Assuming that this galaxy is a merger and that the gas is sourced mainly from
the infalling companion, these metallicities plausibly indicate the gas-phase
metallicity (GPM) of the accreted satellite. Comparison to the local mass-GPM
relation suggests (crudely) that the mass of the accreted system is around
3x10^8 Msun, making NGC 4150 a 1:20 minor merger. A summation of the pixel RSF
mass fractions indicates that the RSF contributes about 2-3 percent of the
stellar mass. This work reaffirms our hypothesis that minor mergers play a
significant role in the evolution of ETGs at late epochs.Comment: 28 pages, 2 tables, accepted for publication in Ap
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