34,473 research outputs found
Collisional deexcitation of exotic hydrogen atoms in highly excited states. II. Cascade calculations
The atomic cascades in mu-p and pbar-p atoms have been studied in detail
using new results for the cross-sections of the scattering of highly excited
exotic atoms from molecular hydrogen. The cascade calculations have been done
with an updated version of the extended standard cascade model that computes
the evolution in the kinetic energy from the beginning of the cascade. The
resulting X-ray yields, kinetic energy distributions, and cascade times are
compared with the experimental data.Comment: 13 pages, 23 figure
Collisional deexcitation of exotic hydrogen atoms in highly excited states. I. Cross-sections
The deexcitation of exotic hydrogen atoms in highly excited states in
collisions with hydrogen molecules has been studied using the
classical-trajectory Monte Carlo method. The Coulomb transitions with large
change of principal quantum number n have been found to be the dominant
collisional deexcitation mechanism at high n. The molecular structure of the
hydrogen target is shown to be essential for the dominance of transitions with
large \Delta n. The external Auger effect has been studied in the eikonal
approximation. The resulting partial wave cross-sections are consistent with
unitarity and provide a more reliable input for cascade calculations than the
previously used Born approximation.Comment: 10 pages, 20 figure
Strategic management of nitrogen within an organic cropping system using digestate from biogas production of recirculated crop residues
This project investigates strategic management of nitrogen by integrating crop residue management with biogas production. The approach offers potential for diversified farmer income, as food crops, feedstock for biogas and digestate for nutrient cycling are produced simultaneously. This type of diversification provides multifunctional solutions in organic farming, especially in production without access to animal manure. Biogas production from crop residues offers the possibility of reducing both emissions and leaching of nutrients to the surrounding ecosystems, as compared to the case where crop residue is incorporated into the soil for decomposition (Baggs et al. 2000; Velthof et al. 2002). This type of multifunctional cropping system provides solutions that can also help to solve issues on conventional farms, such as N emissions, and can also provide local production of biogas
A solvable non-conservative model of Self-Organized Criticality
We present the first solvable non-conservative sandpile-like critical model
of Self-Organized Criticality (SOC), and thereby substantiate the suggestion by
Vespignani and Zapperi [A. Vespignani and S. Zapperi, Phys. Rev. E 57, 6345
(1998)] that a lack of conservation in the microscopic dynamics of an SOC-model
can be compensated by introducing an external drive and thereby re-establishing
criticality. The model shown is critical for all values of the conservation
parameter. The analytical derivation follows the lines of Broeker and
Grassberger [H.-M. Broeker and P. Grassberger, Phys. Rev. E 56, 3944 (1997)]
and is supported by numerical simulation. In the limit of vanishing
conservation the Random Neighbor Forest Fire Model (R-FFM) is recovered.Comment: 4 pages in RevTeX format (2 Figures) submitted to PR
Reconsidering "the love of art" : evaluating the potential of art museum outreach
Art museums have long been identified as bastions of social and cultural exclusion. This conclusion was best evidenced by the large-scale 1967 French study by Bourdieu and Darbel demonstrating the exclusionary nature of “The Love of Art.” However, in recent years there have been increasing efforts to reach out to a broader range of visitors beyond conventional
audiences. The present study investigates the impacts of an outreach program at a UK art museum, which sought to engage socially excluded young mothers. This study employs ethnographic research methods on a longitudinal basis to develop qualitative insights about the program seeking to mitigate cultural exclusion. While the study’s findings uphold many longstanding critiques of art museums’ conventional approaches, the study also indicates that carefully designed outreach activities can overcome such limitations and enhance cultural
engagement. Thus, art museums’ limited appeal is tied to problematic public engagement practices that can be changed
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