3,360 research outputs found
Diffractive wave guiding of hot electrons by the Au (111) herringbone reconstruction
The surface potential of the herringbone reconstruction on Au(111) is known
to guide surface-state electrons along the potential channels. Surprisingly, we
find by scanning tunneling spectroscopy that hot electrons with kinetic
energies twenty times larger than the potential amplitude (38 meV) are still
guided. The efficiency even increases with kinetic energy, which is reproduced
by a tight binding calculation taking the known reconstruction potential and
strain into account. The guiding is explained by diffraction at the
inhomogeneous electrostatic potential and strain distribution provided by the
reconstruction.Comment: 10 pages, 9 figure
Recognition map analysis and crop acreage estimation using Skylab EREP data
There are no author-identified significant results in this report
Recognition map analysis and crop acreage estimation
There are no author-identified significant results in this report
Economic evaluation of crop acreage estimation by multispectral remote sensing
The author has identified the following significant results. Photointerpretation of S190A and S190B imagery showed significantly better resolution with the S190B system. A small tendancy to underestimate acreage was observed. This averaged 6 percent and varied with field size. The S190B system had adequate resolution for acreage measurement but the color film did not provide adequate contrast to allow detailed classification of ground cover from imagery of a single date. In total 78 percent of the fields were correctly classified but with 56 percent correct for the major crop, corn
Investigation of Skylab data
There are no author-identified significant results in this report
Wave function mapping in graphene quantum dots with soft confinement
Using low-temperature scanning tunneling spectroscopy, we map the local
density of states (LDOS) of graphene quantum dots supported on Ir(111). Due to
a band gap in the projected Ir band structure around the graphene K point, the
electronic properties of the QDs are dominantly graphene-like. Indeed, we
compare the results favorably with tight binding calculations on the honeycomb
lattice based on parameters derived from density functional theory. We find
that the interaction with the substrate near the edge of the island gradually
opens a gap in the Dirac cone, which implies soft-wall confinement.
Interestingly, this confinement results in highly symmetric wave functions.
Further influences of the substrate are given by the known moir{\'e} potential
and a 10% penetration of an Ir surface resonanceComment: 7 pages, 11 figures, DFT calculations directly showing the origin of
soft confinment, correct identification of the state penetrating from Ir(111)
into graphen
Sound modes in hot nuclear matter
The propagation of the isoscalar and isovector sound modes in a hot nuclear
matter is considered. The approach is based on the collisional kinetic theory
and takes into account the temperature and memory effects. It is shown that the
sound velocity and the attenuation coefficient are significantly influenced by
the Fermi surface distortion (FSD). The corresponding influence is much
stronger for the isoscalar mode than for the isovector one. The memory effects
cause a non-monotonous behavior of the attenuation coefficient as a function of
the relaxation time leading to a zero-to-first sound transition with increasing
temperature. The mixing of both the isoscalar and the isovector sound modes in
an asymmetric nuclear matter is evaluated. The condition for the bulk
instability and the instability growth rate in the presence of the memory
effects is studied. It is shown that both the FSD and the relaxation processes
lead to a shift of the maximum of the instability growth rate to the longer
wave length region.Comment: 15 pages, 4 figures, submitted to Phys. Rev.
Fast diffusion of a Lennard-Jones cluster on a crystalline surface
We present a Molecular Dynamics study of large Lennard-Jones clusters
evolving on a crystalline surface. The static and the dynamic properties of the
cluster are described. We find that large clusters can diffuse rapidly, as
experimentally observed. The role of the mismatch between the lattice
parameters of the cluster and the substrate is emphasized to explain the
diffusion of the cluster. This diffusion can be described as a Brownian motion
induced by the vibrationnal coupling to the substrate, a mechanism that has not
been previously considered for cluster diffusion.Comment: latex, 5 pages with figure
Nutrient-based dietary patterns and the risk of head and neck cancer: a pooled analysis in the International Head and Neck Cancer Epidemiology consortium
Background The association between dietary patterns and head and neck cancer has rarely been addressed. Patients and methods We used individual-level pooled data from five case-control studies (2452 cases and 5013 controls) participating in the International Head and Neck Cancer Epidemiology consortium. A posteriori dietary patterns were identified through a principal component factor analysis carried out on 24 nutrients derived from study-specific food-frequency questionnaires. Odds ratios (ORs) and corresponding 95% confidence intervals (CIs) were estimated using unconditional logistic regression models on quintiles of factor scores. Results We identified three major dietary patterns named ‘animal products and cereals', ‘antioxidant vitamins and fiber', and ‘fats'. The ‘antioxidant vitamins and fiber' pattern was inversely related to oral and pharyngeal cancer (OR= 0.57, 95% CI 0.43-0.76 for the highest versus the lowest score quintile). The ‘animal products and cereals' pattern was positively associated with laryngeal cancer (OR= 1.54, 95% CI 1.12-2.11), whereas the ‘fats' pattern was inversely associated with oral and pharyngeal cancer (OR= 0.78, 95% CI 0.63-0.97) and positively associated with laryngeal cancer (OR= 1.69, 95% CI 1.22-2.34). Conclusions These findings suggest that diets rich in animal products, cereals, and fats are positively related to laryngeal cancer, and those rich in fruit and vegetables inversely related to oral and pharyngeal cance
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