1,785 research outputs found
PER UNIT COSTS TO OWN AND OPERATE FARM MACHINERY
Entropy and jackknife estimation procedures were used to find that custom rates are 20.3% lower than the true cost to own and operate machinery for an average size Kansas farm. A method was then developed to estimate a farms total machinery costs with which to benchmark machinery costs.Farm Management,
Silvoarable agroforestry
Introduction: A silvoarable system of land management implies the cultivation of trees and arable crops on the same area of land, a system practised quite commonly in southern Europe and in the tropics. The system comprises two components: tree rows, generally one tree wide, and arable alleys, alternating across the field. The first major development of silvoarable practice in the UK took place during the 1960s and 1970s when Bryant & May established extensive poplar plantations on lowland farmland in southern England to supply their own market for match veneer timber (Beaton, 1987). Since the demise of the Bryant Sr May market for match timber in 1978, interest in the potential for silvoarable systems lay dormant until the advent of food crop surpluses in the 1980s
Empirical 2MASS-WFC3/IR filter transformations from synthetic photometry
Near-infrared bandpasses on spaceborne observatories diverge from their
ground-based counterparts as they are free of atmospheric telluric absorption.
Available transformations between respective filter systems in the literature
rely on theoretical stellar atmospheres, which are known to have difficulties
reproducing observed spectral energy distributions of cool giants. We present
new transformations between the 2MASS and HST WFC3/IR F110W, F125W, &
F160W photometric systems based on synthetic photometry of empirical stellar
spectra from four spectral libraries. This sample comprises over 1000
individual stars, which together span nearly the full HR diagram and sample
stellar populations from the solar neighborhood out to the Magellanic Clouds,
covering a broad range of ages, metallicities, and other relevant stellar
properties. In addition to global color-dependent transformations, we examine
band-to-band differences for cool, luminous giant stars in particular,
including multiple types of primary distance indicators.Comment: 24 pages, 15 figures, accepted to A
Final targeting strategy for the sloan digital sky survey IV Apache Point Observatory galactic evolution experiment 2 North Survey
ArtĂculo escrito por más de 60 autores.The Apache Point Observatory Galactic Evolution Experiment 2 (APOGEE-2) is a dual-hemisphere, near-infrared (NIR), spectroscopic survey with the goal of producing a chemodynamical mapping of the Milky Way. The targeting for APOGEE-2 is complex and has evolved with time. In this paper, we present the updates and additions to the initial targeting strategy for APOGEE-2N presented in Zasowski et al. (2017). These modifications come in two implementation modes: (i) “Ancillary Science Programs” competitively awarded to Sloan Digital Sky Survey IV PIs through proposal calls in 2015 and 2017 for the pursuit of new scientific avenues outside the main survey, and (ii) an effective 1.5 yr expansion of the survey, known as the Bright Time Extension (BTX), made posible through accrued efficiency gains over the first years of the APOGEE-2N project. For the 23 distinct ancillary programs, we provide descriptions of the scientific aims, target selection, and how to identify these targets within the APOGEE-2 sample. The BTX permitted changes to the main survey strategy, the inclusion of new programs in response to scientific discoveries or to exploit major new data sets not available at the outset of the survey design, and expansions of existing programs to enhance their scientific success and reach. After describing the motivations, implementation, and assessment of these programs, we also leave a summary of lessons learned from nearly a decade of APOGEE-1 and APOGEE-2 survey operations. A companion paper, F. Santana et al. (submitted; AAS29036), provides a complementary presentation of targeting modifications relevant to APOGEE-2 operations in the Southern Hemisphere
Common and specific impairments in attention functioning in girls with chromosome 22q11.2 deletion, fragile X or Turner syndromes.
BACKGROUND: Chromosome 22q11.2 deletion syndrome (22q11.2DS), fragile X syndrome (FXS), and Turner syndrome (TS) are complex and variable developmental syndromes caused by different genetic abnormalities; yet, they share similar cognitive impairments in the domains of numbers, space, and time. The atypical development of foundational neural networks that underpin the attentional system is thought to result in further impairments in higher-order cognitive functions. The current study investigates whether children with similar higher-order cognitive impairments but different genetic disorders also show similar impairments in alerting, orienting, and executive control of attention.
METHODS: Girls with 22q11.2DS, FXS, or TS and typically developing (TD) girls, aged 7 to 15 years, completed an attention network test, a flanker task with alerting and orienting cues. Exploration of reaction times and accuracy allowed us to test for potential commonalities in attentional functioning in alerting, orienting, and executive control. Linear regression models were used to test whether the predictors of group and chronological age were able to predict differences in attention indices.
RESULTS: Girls with 22q11.2DS, FXS, or TS demonstrated unimpaired function of the alerting system and impaired function of the executive control system. Diagnosis-specific impairments were found such that girls with FXS made more errors and had a reduced orienting index, while girls with 22q11.2DS showed specific age-related deficits in the executive control system.
CONCLUSIONS: These results suggest that the control but not the implementation of attention is selectively impaired in girls with 22q11.2DS, TS or FXS. Additionally, the age effect on executive control in girls with 22q11.2DS implies a possible altered developmental trajectory
Welcome to the Twilight Zone: The Mid-Infrared Properties of Poststarburst Galaxies
We investigate the optical and Wide-field Survey Explorer (WISE) colors of
"E+A" identified post-starburst galaxies, including a deep analysis on 190
post-starbursts detected in the 2{\mu}m All Sky Survey Extended Source Catalog.
The post-starburst galaxies appear in both the optical green valley and the
WISE Infrared Transition Zone (IRTZ). Furthermore, we find that post-starbursts
occupy a distinct region [3.4]-[4.6] vs. [4.6]-[12] WISE colors, enabling the
identification of this class of transitioning galaxies through the use of
broad-band photometric criteria alone. We have investigated possible causes for
the WISE colors of post-starbursts by constructing a composite spectral energy
distribution (SED), finding that mid-infrared (4-12{\mu}m) properties of
post-starbursts are consistent with either 11.3{\mu}m polycyclic aromatic
hydrocarbon emission, or Thermally Pulsating Asymptotic Giant Branch (TP-AGB)
and post-AGB stars. The composite SED of extended post- starburst galaxies with
22{\mu}m emission detected with signal to noise >3 requires a hot dust
component to produce their observed rising mid-infrared SED between 12 and
22{\mu}m. The composite SED of WISE 22{\mu}m non-detections (S/N<3), created by
stacking 22{\mu}m images, is also flat, requiring a hot dust component. The
most likely source of this mid-infrared emission of these E+A galaxies is a
buried active galactic nucleus. The inferred upper limit to the Eddington
ratios of post-starbursts are 1e-2 to 1e-4, with an average of 1e-3. This
suggests that AGNs are not radiatively dominant in these systems. This could
mean that including selections able to identify active galactic nuclei as part
of a search for transitioning and post-starburst galaxies would create a more
complete census of the transition pathways taken as a galaxy quenches its star
formation.Comment: 13 pages, 11 figures, accepted for publication in the Astrophysical
Journa
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