946 research outputs found
Channel plasmon-polaritons: modal shape, dispersion, and losses
We theoretically study channel plasmon-polaritons (CPPs) with a geometry
similar to that in recent experiments at telecom wavelengths (Bozhevolnyi et
al., Nature 440, 508 (2006)). The CPP modal shape, dispersion relation, and
losses are simulated using the multiple multipole method and the finite
difference time domain technique. It is shown that, with the increase of the
wavelength, the fundamental CPP mode shifts progressively towards the groove
opening, ceasing to be guided at the groove bottom and becoming hybridized with
wedge plasmon-polaritons running along the groove edges.Comment: 4 pages, 4 figure
Automatic photointerpretation for land use management in Minnesota
The author has identified the following significant results. Automatic photointerpretation techniques were utilized to evaluate the feasibility of data for land use management. It was shown that ERTS-1 MSS data can produce thematic maps of adequate resolution and accuracy to update land use maps. In particular, five typical land use areas were mapped with classification accuracies ranging from 77% to over 90%
RF System Upgrades to the Advanced Photon Source Linear Accelerator in Support of the Fel Operation
The S-band linear accelerator, which was built to be the source of particles
and the front end of the Advanced Photon Source injector, is now also being
used to support a low-energy undulator test line (LEUTL) and to drive a
free-electron laser (FEL). The more severe rf stability requirements of the FEL
have resulted in an effort to identify sources of phase and amplitude
instability and implement corresponding upgrades to the rf generation chain and
the measurement system. Test data and improvements implemented and planned are
describedComment: LC 2000 (3 pages, 6 figures
Development of integrated management practices for the control of Chinese tallow (Triadica sebifera)
Chinese tallow (Triadica sebifera) tree is an aggressive, fast growing, highly adaptable invasive tree of the southeastern United States coastal region. Our study is located on Parris Island Marine Corps Recruit Depot (MCRD) in Beaufort County, South Carolina. Parris Island MCRD. Chinese tallow has been managed on Parris Island MCRD since 2001through the use of herbicides primarily with ‘hack and squirt’ methodology. In 2010, invasive species presence and abundance on Parris Island MCRD was surveyed in order to monitor the Chinese tallow population and to assess the effectiveness of previous control efforts. Results from this survey suggest there is a need for a more effective management approach because the Chinese tallow population in some areas had increased despite herbicide applications. In this study, we seek to find an effective approach for managing Chinese tallow while, at the same time, promoting native species diversity and restoring the forest ecosystem. We will test several integrated treatments including mechanical, herbicide and fire to determine their efficacy on Chinese tallow control as well as their potential adverse effects on native vegetation. The goal of the study is to determine the most effective integrated treatment of Chinese tallow
Testing and Implementation Progress on the Advanced Photon Source (APS) Linear Accelerator (Linac) High-Power S-band Switching System
An S-band linear accelerator is the source of particles and the front end of
the Advanced Photon Source injector. In addition, it supports a low-energy
undulator test line (LEUTL) and drives a free-electron laser (FEL). A
waveguide-switching and distribution system is now under construction. The
system configuration was revised to be consistent with the recent change to
electron-only operation. There are now six modulator-klystron subsystems, two
of which are being configured to act as hot spares for two S-band transmitters
each, so that no single failure will prevent injector operation. The two
subsystems are also used to support additional LEUTL capabilities and off-line
testing. Design considerations for the waveguide-switching subsystem, topology
selection, control and protection provisions, high-power test results, and
current status are describedComment: Linac 2000 paper No. THE07 3 pages with 3 figure
Weak decays of 4He-Lambda
We measured the lifetime and the mesonic and non-mesonic decay rates of the
4He-Lambda hypernucleus. The hypernuclei were created using a 750 MeV/c
momentum K- beam on a liquid 4He target by the reaction 4He(K-,pi-)4He-Lambda.
The 4He-Lambda lifetime was directly measured using protons from Lambda p -> n
p non-mesonic decay (also referred to as proton-stimulated decay) and was found
to have a value of tau = 245 +/- 24 ps. The mesonic decay rates were determined
from the observed numbers of pi-'s and pi0's as Gamma_pi-/Gamma_tot = 0.270 +/-
0.024 and Gamma_pi0/Gamma_tot = 0.564 +/- 0.036, respectively, and the values
of the proton- and neutron-stimulated decay rates were extracted as
Gamma_p/Gamma_tot = 0.169 +/- 0.019 and Gamma_n/Gamma_tot <= 0.032 (95% CL),
respectively. The effects of final-state interactions and possible 3-body
Lambda N N decay contributions were studied in the context of a simple model of
nucleon-stimulated decay. Nucleon-nucleon coincidence events were observed and
were used in the determination of the non-mesonic branching fractions. The
implications of the results of this analysis were considered for the empirical
Delta I = 1/2 rule and the decay rates of the 4H-Lambda hypernucleus.Comment: 15 pages, 11 figures, published in PRC, revised content to match
published versio
Mechanisms of Chinese tallow (Triadica sebifera) invasion and their management implications – A review
Ecosystems are under increasing stress from environmental change, including invasion by non-native species that can disrupt ecological processes and functions. Chinese tallow [Triadica sebifera (L.) Small] is a highly invasive tree species in southeastern US forests, prairies, and wetlands, and effectively managing this invasive species is a significant challenge for scientists and land managers. In this review, we synthesize the literature on invasion ecology and management of Chinese tallow. Our review suggests that the invaded range of Chinese tallow is currently limited by dispersal in many areas and by low temperatures and low soil moisture, and by high soil salinity and frequent flooding in others, but these barriers may be overcome by increased dispersal, phenotypic plasticity, and/or rapid evolution. Invasions by Chinese tallow are facilitated by both the invasiveness of the species and the invasibility of the recipient communities. Invasiveness of Chinese tallow has been attributed to fast growth, high fecundity, a persistent seed bank, aggressive resprouting, abiotic stress tolerance, and the ability to transform fire maintained ecosystems. Some of these traits may be enhanced in invasive populations. Anthropogenic and natural disturbances, lack of herbivore pressure, and facilitation by soil microbes enhance the intensity of Chinese tallow invasions. Biological control of Chinese tallow is being developed. Treatments such as herbicides, prescribed fire, and mechanical control can effectively control Chinese tallow at the local scale. A combination of these treatments improves results. However, a proactive management approach would simultaneously achieve invasion control and promote subsequent ecological restoration, especially in the context of legacy effects, secondary invasions, and/or variable ecosystem responses to different control treatments. Future research should clarify the roles of species invasiveness and community invasibility, increase our understanding of the effects of Chinese tallow in invaded communities, and develop viable management regimes that are effective in both controlling or reducing the probability of Chinese tallow invasion and restoring desired native communities
Ocorrência de fascioliasis humana no município de Volta Redonda, RJ, Brasil
Through the result of coprologics exams, accomplished in patients assisted in Volta Redonda hospitals, the first occurrence of the human fascioliasis is marked in the State of Rio de Janeiro, Brazil.Através do resultado de exames coprológicos realizados em pacientes atendidos em postos de saúde e hospitais do município de Volta Redonda, assinala-se a primeira ocorrência da fascioliasis humana no Estado do Rio de Janeiro, Brasil
A particle-hole model approach for hypernuclei
A particle-hole model is developed to describe the excitation spectrum of
single lambda hypernuclei and the possible presence of collective effects is
explored by making a comparison with the mean-field calculations. Results for
the spectra of 12C, 16O, 40Ca, 90Zr and 208Pb single lambda hypernuclei are
shown. The comparison with the available experimental data is satisfactory. We
find that collective phenomena are much less important in hypernuclei than in
ordinary nuclei.Comment: 24 pages, 5 eps figures, accepted for publication in Nucl. Phys.
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