2,062 research outputs found
On the Coulomb-Sturmian matrix elements of the Coulomb Green's operator
The two-body Coulomb Hamiltonian, when calculated in Coulomb-Sturmian basis,
has an infinite symmetric tridiagonal form, also known as Jacobi matrix form.
This Jacobi matrix structure involves a continued fraction representation for
the inverse of the Green's matrix. The continued fraction can be transformed to
a ratio of two hypergeometric functions. From this result we find
an exact analytic formula for the matrix elements of the Green's operator of
the Coulomb Hamiltonian.Comment: 8 page
Proximity effects of high voltage electric power transmission lines on ornamental plant growth
The proximity effects of high voltage electric power transmission lines on Leyland Cypress (xCupressocyparis leylandii (Dallim. and A.B. Jacks.) Dallim) and Japanese Privet (Ligustrum japonicum Thunb.) growth were examined in a private nursery located in Sakarya, Turkey. Five transect were randomly chosen in both leylandii and privet lots in the nursery. In the summer of 2009, starting from under the power line 12 sampling point for every five meters away from the power line on each transaction was located. From these sampling points, five seedlings for each species were randomly chosen. From each sampling seedlings, five - seven leaves (for private) or spurs (for leylandii) were collected from lower-, middle- and upper-crown. For each sampling seedling diameter at breast height (dbh) were measured with a caliper. Within the laboratory, the projected surface area (SLA) of needles and leaves were determined using a leaf area meter. The relationship among measured seedling variables and the proximity to high voltage electric power transmission lines were evaluated using correlation. The effects of proximity to power-line on specific leaf area and seedling dbh were tested with an analysis of variance procedure (ANOVA). Tukey’s HSD test with alpha = 0.05 was performed to compare means. The result of the data revealed that the mean of seedling dbh at 55 m away from the power line was about 25% smaller than that of the seedlings underneath the power line. The data also showed that there was a gradual decrease at dbh value of the privet with the distance from the power line. Seedling mean dbh value at the 25th m sampling point was about 10% lower than that of the seedlings underneath the power line. At the 40th m sampling point this dbh value was about 17 and 8% lower than those of the seedlings underneath the power line and of the seedling at 25th m sampling point, respectively. Specific leaf area after the 30th m away from the power line has been decreasing. The SLA value at the 30th m is about 17% lower than that of the seedling underneath the power line.Key words: magnetic field, ornamental plant growth, power transmission line, Leyland Cypress, Japanese Privet
Ultrafine conducting fibers: metallization of poly(acrylonitrile-co-glycidyl methacrylate) nanofibers
Electrospun poly(glycidylmethacrylate) (PGMA) and poly(acrylonitrile-co-glycidyl methacrylate) (P(AN-GMA)) nanofibers were coated with monodisperse silver nanoparticles by using an electroless plating technique at ambient conditions. Oxirane groups on the surface of nanofibers were replaced with reducing agent, hydrazine. Surface modified nanofibers were allowed to react with ammonia solution of AgNO3. A redox reaction takes place and metallic silver nucleate on fibers surface. Parameters affecting the particle size were determined
Room-temperature larger-scale highly ordered nanorod imprints of ZnO film
Cataloged from PDF version of article.Room-temperature large-scale highly ordered nanorod-patterned
ZnO films directly integrated on III-nitride light-emitting diodes (LEDs) are
proposed and demonstrated via low-cost modified nanoimprinting, avoiding
a high-temperature process. with a 600 nm pitch on top of a critical 200 nm
thick Imprinting ZnO nanorods of 200 nm in diameter and 200 nm in height
continuous ZnO wetting layer, the light output power of the resulting
integrated ZnO-nanorod-film/semi-transparent metal/GaN/InGaN LED
shows a two-fold enhancement (100% light extraction efficiency
improvement) at the injection current of 150 mA, in comparison with the
conventional LED without the imprint film. The increased optical output is
well explained by the enhanced light scattering and outcoupling of the ZnOrod
structures along with the wetting film, as verified by the numerical
simulations. The wetting layer is found to be essential for better impedance
matching. The current-voltage characteristics and electroluminescence
measurements confirm that there is no noticeable change in the electrical or
spectral properties of the final LEDs after ZnO-nanorod film integration.
These results suggest that the low-cost high-quality large-scale ZnOnanorod
imprints hold great promise for superior LED light extraction.
©2013 Optical Society of Americ
EfficientTempNet: Temporal Super-Resolution of Radar Rainfall
Rainfall data collected by various remote sensing instruments such as radars
or satellites has different space-time resolutions. This study aims to improve
the temporal resolution of radar rainfall products to help with more accurate
climate change modeling and studies. In this direction, we introduce a solution
based on EfficientNetV2, namely EfficientTempNet, to increase the temporal
resolution of radar-based rainfall products from 10 minutes to 5 minutes. We
tested EfficientRainNet over a dataset for the state of Iowa, US, and compared
its performance to three different baselines to show that EfficientTempNet
presents a viable option for better climate change monitoring.Comment: Published as a workshop paper at Tackling Climate Change with Machine
Learning, ICLR 202
Sneutrino Dark Matter: Symmetry Protection and Cosmic Ray Anomalies
We present an R-parity conserving model of sneutrino dark matter within a
Higgs-philic U(1)' extension of the minimal supersymmetric standard model. In
this theory, the mu parameter and light Dirac neutrino masses are generated
naturally upon the breaking of the U(1)' gauge symmetry. The leptonic and
hadronic decays of sneutrinos in this model, taken to be the lightest and
next-to-lightest superpartners, allow for a natural fit to the recent results
reported by the PAMELA experiment.Comment: Revised to match the published version; 11 pages (2 column format), 1
table, 6 figures, to appear in PR
Shear Viscosity in a Perturbative Quark-Gluon-Plasma
Among the key features of hot and dense QCD matter produced in
ultra-relativistic heavy-ion collisions at RHIC is its very low shear
viscosity, indicative of the properties of a near-ideal fluid, and a large
opacity demonstrated by jet energy loss measurements. In this work, we utilize
a microscopic transport model based on the Boltzmann equation with quark and
gluon degrees of freedom and cross sections calculated from perturbative
Quantum Chromodynamics to simulate an ideal Quark-Gluon-Plasma in full thermal
and chemical equilibrium. We then use the Kubo formalism to calculate the shear
viscosity to entropy density ratio of the medium as a function of temperature
and system composition. One of our key results is that the shear viscosity over
entropy-density ratio becomes invariant to the chemical composition of
the system when plotted as a function of energy-density instead of temperature.Comment: 11 pages, 8 figures: version #2 contains some revisions and added
references to clarify relationship to previously published wor
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