6,449 research outputs found
Conservation Tillage Increases Water Use Efficiency of Spring Wheat by Optimizing Water Transfer in a Semi-Arid Environment
Water availability is a major constraint for crop production in semiarid environments.
The impact of tillage practices on water potential gradient, water transfer resistance, yield, and water
use e�ciency (WUEg) of spring wheat was determined on the western Loess Plateau. Six tillage
practices implemented in 2001 and their e�ects were determined in 2016 and 2017 including
conventional tillage with no straw (T), no-till with straw cover (NTS), no-till with no straw (NT),
conventional tillage with straw incorporated (TS), conventional tillage with plastic mulch (TP),
and no-till with plastic mulch (NTP). No-till with straw cover, TP, and NTP significantly improved
soil water potential at the seedling stage by 42, 47, and 57%, respectively; root water potential at the
seedling stage by 34, 35, and 51%, respectively; leaf water potential at the seedling stage by 37, 48,
and 42%, respectively; tillering stage by 21, 24, and 30%, respectively; jointing stage by 28, 32, and 36%,
respectively; and flowering stage by 10, 26, and 16%, respectively, compared to T. These treatments
also significantly reduced the soil–leaf water potential gradient at the 0–10 cm soil depth at the
seedling stage by 35, 48, and 35%, respectively, and at the 30–50 cm soil depth at flowering by 62,
46, and 65%, respectively, compared to T. Thus, NTS, TP, and NTP reduced soil–leaf water transfer
resistance and enhanced transpiration. Compared to T, the NTS, TP, and NTP practices increased
biomass yield by 18, 36, and 40%; grain yield by 28, 22, and 24%; and WUEg by 24, 26, and 24%,
respectively. These results demonstrate that no-till with straw mulch and plastic mulching with
either no-till or conventional tillage decrease the soil–leaf water potential gradient and soil–leaf water
transfer resistance and enhance sustainable intensification of wheat production in semi-arid areas
Optical band edge shift of anatase cobalt-doped titanium dioxide
We report on the optical properties of magnetic cobalt-doped anatase phase
titanium dioxide Ti_{1-x}Co_{x}O_{2-d} films for low doping concentrations, 0
<= x <= 0.02, in the spectral range 0.2 to 5 eV. For well oxygenated films (d
<< 1) the optical conductivity is characterized by an absence of optical
absorption below an onset of interband transitions at 3.6 eV and a blue shift
of the optical band edge with increasing Co concentration. The absence of below
band gap absorption is inconsistent with theoretical models which contain
midgap magnetic impurity bands and suggests that strong on-site Coulomb
interactions shift the O-band to Co-level optical transitions to energies above
the gap.Comment: 5 pages, 4 figures, 1 table; Version 2 - major content revisio
Nanoscale Mechanical Drumming Visualized by 4D Electron Microscopy
With four-dimensional (4D) electron microscopy, we report in situ imaging of the mechanical drumming of a nanoscale material. The single crystal graphite film is found to exhibit global resonance motion that is fully reversible and follows the same evolution after each initiating stress pulse. At early times, the motion appears “chaotic” showing the different mechanical modes present over the micron scale. At longer time, the motion of the thin film collapses into a well-defined fundamental frequency of 1.08 MHz, a behavior reminiscent of mode locking; the mechanical motion damps out after ∼200 μs and the oscillation has a “cavity” quality factor of 150. The resonance time is determined by the stiffness of the material, and for the 75 nm thick and 40 μm square specimen used here we determined Young’s modulus to be 1.0 TPa for the in-plane stress−strain profile. Because of its real-time dimension, this 4D microscopy should have applications in the study of these and other types of materials structures
Bell's inequalities in the tomographic representation
The tomographic approach to quantum mechanics is revisited as a direct tool
to investigate violation of Bell-like inequalities. Since quantum tomograms are
well defined probability distributions, the tomographic approach is emphasized
to be the most natural one to compare the predictions of classical and quantum
theory. Examples of inequalities for two qubits an two qutrits are considered
in the tomographic probability representation of spin states.Comment: 11 pages, comments and references adde
Responses to Increased Moisture Stress and Extremes: Whole Plant Response to Drought under Climate Change
In this chapter, we tackle the physiology of
plant water use from the angle of how this will
be modified in a context of a changing climate.
Two recent reviews cover a number of innovative
aspects to drought research, in particular in relation
to research on roots, and advocate the need
to look at the soil–root–shoot–atmosphere water
management in a comprehensive and dynamic
manner (Vadez et al. 2007, 2008). In the present
chapter, we revisit some of these aspects from
the perspective of changing climatic conditions
and explore the major issues that climate change will bring about, and how it will affect crop
production and in particular under water-limited
conditions. These issues can be broadly grouped
into two categories: (1) thermodynamic aspects
of the soil–plant–atmosphere water relations and
(2) growth and development aspects
Limits on WWgamma and WWZ Couplings from W Boson Pair Production
The results of a search for W boson pair production in pbar-p collisions at
sqrt{s}=1.8 TeV with subsequent decay to emu, ee, and mumu channels are
presented. Five candidate events are observed with an expected background of
3.1+-0.4 events for an integrated luminosity of approximately 97 pb^{-1}.
Limits on the anomalous couplings are obtained from a maximum likelihood fit of
the E_T spectra of the leptons in the candidate events. Assuming identical
WWgamma and WWZ couplings, the 95 % C.L. limits are -0.62<Delta_kappa<0.77
(lambda = 0) and -0.53<lambda<0.56 (Delta_kappa = 0) for a form factor scale
Lambda = 1.5 TeV.Comment: 10 pages, 1 figure, submitted to Physical Review
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Observation of seasonal variation of atmospheric multiple-muon events in the NOvA Near Detector
Using two years of data from the NOvA Near Detector at Fermilab, we report a seasonal variation of cosmic ray induced multiple-muon (Nμ≥2) event rates which has an opposite phase to the seasonal variation in the atmospheric temperature. The strength of the seasonal multiple-muon variation is shown to increase as a function of the muon multiplicity. However, no significant dependence of the strength of the seasonal variation of the multiple-muon variation is seen as a function of the muon zenith angle, or the spatial or angular separation between the correlated muons
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First measurement of neutrino oscillation parameters using neutrinos and antineutrinos by NOvA.
The NOvA experiment has seen a 4.4σ signal of ν[over ¯]_{e} appearance in a 2 GeV ν[over ¯]_{μ} beam at a distance of 810 km. Using 12.33×10^{20} protons on target delivered to the Fermilab NuMI neutrino beamline, the experiment recorded 27 ν[over ¯]_{μ}→ν[over ¯]_{e} candidates with a background of 10.3 and 102 ν[over ¯]_{μ}→ν[over ¯]_{μ} candidates. This new antineutrino data are combined with neutrino data to measure the parameters |Δm_{32}^{2}|=2.48_{-0.06}^{+0.11}×10^{-3} eV^{2}/c^{4} and sin^{2}θ_{23} in the ranges from (0.53-0.60) and (0.45-0.48) in the normal neutrino mass hierarchy. The data exclude most values near δ_{CP}=π/2 for the inverted mass hierarchy by more than 3σ and favor the normal neutrino mass hierarchy by 1.9σ and θ_{23} values in the upper octant by 1.6σ
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Search for the disappearance of muon antineutrinos in the NuMI neutrino beam
We report constraints on antineutrino oscillation parameters that were obtained by using the two MINOS detectors to measure the 7% muon antineutrino component of the NuMI neutrino beam. In the Far Detector, we select 130 events in the charged-current muon antineutrino sample, compared to a prediction of 136.4 ± 11.7(stat)^(+10.2)_(-8.9)(syst) events under the assumption │Δm^2│ = 2.32 X 10^(-3) eV^2, sin^2(2θ) = 1.0
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Measurement of the underground atmospheric muon charge ratio using the MINOS Near Detector
The magnetized MINOS Near Detector, at a depth of 225 mwe, is used to measure the atmospheric muon charge ratio. The ratio of observed positive to negative atmospheric muon rates, using 301 days of data, is measured to be 1.266±0.001(stat)_(-0.014)^(+0.015)(syst). This measurement is consistent with previous results from other shallow underground detectors and is 0.108±0.019(stat+syst) lower than the measurement at the functionally identical MINOS Far Detector at a depth of 2070 mwe. This increase in charge ratio as a function of depth is consistent with an increase in the fraction of muons arising from kaon decay for increasing muon surface energie
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