2,624 research outputs found
Chiral Symmetry and N*(1440) -> N pi pi Decay
The N*(1440) -> N pi pi decay is studied by making use of the chiral
reduction formula. This formula suggests a scalar-isoscalar pion-baryon contact
interaction which is absent in the recent study of Hern{\'a}ndez et al. The
contact interaction is introduced into their model, and is found to be
necessary for the simultaneous description of g_{RN pi pi} and the pi-pi and
pi-N invariant mass distributions.Comment: 12 page
Potential for ultrafast dynamic chemical imaging with few-cycle infrared lasers
We studied the photoelectron spectra generated by an intense few-cycle
infrared laser pulse. By focusing on the angular distributions of the back
rescattered high energy photoelectrons, we show that accurate differential
elastic scattering cross sections of the target ion by free electrons can be
extracted. Since the incident direction and the energy of the free electrons
can be easily changed by manipulating the laser's polarization, intensity, and
wavelength, these extracted elastic scattering cross sections, in combination
with more advanced inversion algorithms, may be used to reconstruct the
effective single-scattering potential of the molecule, thus opening up the
possibility of using few-cycle infrared lasers as powerful table-top tools for
imaging chemical and biological transformations, with the desired unprecedented
temporal and spatial resolutions.Comment: 16 pages, 6 figure
A simple but useful method of screening for mesenteric ischemia secondary to acute aortic dissection
Quantitative rescattering theory for laser-induced high-energy plateau photoelectron spectra
A comprehensive quantitative rescattering (QRS) theory for describing the
production of high-energy photoelectrons generated by intense laser pulses is
presented. According to the QRS, the momentum distributions of these electrons
can be expressed as the product of a returning electron wave packet with the
elastic differential cross sections (DCS) between free electrons with the
target ion. We show that the returning electron wave packets are determined
mostly by the lasers only, and can be obtained from the strong field
approximation. The validity of the QRS model is carefully examined by checking
against accurate results from the solution of the time-dependent Schr\"odinger
equation for atomic targets within the single active electron approximation. We
further show that experimental photoelectron spectra for a wide range of laser
intensity and wavelength can be explained by the QRS theory, and that the DCS
between electrons and target ions can be extracted from experimental
photoelectron spectra. By generalizing the QRS theory to molecular targets, we
discuss how few-cycle infrared lasers offer a promising tool for dynamic
chemical imaging with temporal resolution of a few femtoseconds.Comment: 19 pages, 19 figure
Using a Generalized Linear Mixed Model Framework to Account for Spatial Variability in a Comparison of Orchard Sprayer Efficacy
Uniform application of pesticides in vineyard and orchard systems can be difficult to achieve due to variability in the density and structure of the crop canopy. Depending on the equipment used and environmental conditions, applications can result in poor spray coverage, spray drift, and wasted spray which, in turn, are manifested as a combination of poor pesticide efficacy, economic losses and potential environmental problems for the grower. A study was therefore designed and carried out to test new sprayer equipment aimed at addressing these issues. Statistically, the study presented a unique replicated three dimensional spatial design which captured response variability (coverage) both within and across trees in an orchard setting. Application of a generalized linear mixed model framework allowed comparison of sprayer designs in terms of their application efficiencies while accounting for the intra- and inter-tree correlation of the coverage response. Examples demonstrating various models and their associated correlation structures are given and the resulting interpretations discussed
Nature
In this chapter we explore the nexus of Nature, Human and the Built Environment and how combined they shape and define the mindset required for regenerative sustainability. Importantly it demonstrates how rethinking sustainability must lead to regenerative economics, the central aspect of RESTORE. This chapter is based upon a number of patterns, developed throughout the short life of the working group, as the critical areas deemed necessary to scale jump from sustainability as usual (BAU) to Restorative Sustainability and on to Regenerative Sustainability
SPATIAL STATISTICAL ANALYSIS FOR THE AREA-OF-INFLUENCE EXPERIMENTS
The area-of-influence (AOI) approach to quantifying crop/weed competition involves measuring the effect of individual weed plants on crop growth and yield at specified distances away from the weed plant. AOI experiments are often analyzed using classical statistical techniques based on the assumption that successive observations on crop response are independent in spite of their distribution in space. However, as the distance varies along the row, the competitive ability will vary spatially so that observations located nearby are expected to be more alike than those separated by large distances. Analyses based on spatial dependencies will therefore provide a more comprehensive understanding of factors influencing crop yield reductions. A spatial statistical approach for analyzing AOI experiments is presented and applications are demonstrated using data from a field experiment in South Central Idaho designed to determine the interference of three broadleaf weed species in sugarbeets
Hadronic Masses and Regge Trajectories
A comprehensive phenomenological analysis of experimental data and some
theoretical models is presented here (for mesons) to critically discuss how
Regge trajectory parameters depend on flavor. Through analytic continuation of
physical trajectories (obtained from resonance data) into the space like
region, we derive the suppression factor for heavy flavor production. The case
of our D Regge exchange, both for D and production, is considered
in some detail. Good agreement with data is reached confirming that indeed the
slopes of heavier flavors decrease. This result suggests that the confinement
potential has a substantial dependence on the quark masses. In a simple
non-relativistic model, constrained to produce linear Regge trajectories, it is
shown that a linear quark mass dependence is required (in the confinement part
of the potential) in order for the slope to decrease in the appropriate way.Comment: 19 pages, 9 Figures, IV Table
Simulation of guiding of multiply charged projectiles through insulating capillaries
Recent experiments have demonstrated that highly charged ions can be guided
through insulating nanocapillaries along the direction of the capillary axis
for a surprisingly wide range of injection angles. Even more surprisingly, the
transmitted particles remain predominantly in their initial charge state, thus
opening the pathway to the construction of novel ion-optical elements without
electric feedthroughs. We present a theoretical treatment of this
self-organized guiding process. We develop a classical trajectory transport
theory that relates the microscopic charge-up with macroscopic material
properties. Transmission coefficients, angular spread of transmitted particles,
and discharge characteristics of the target are investigated. Partial agreement
with experiment is found
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