452 research outputs found
Interaction of the Electromagnetic p-Waves with Thin Metal Films
For the first time it is shown that for thin metallic films thickness of
which not exceed thickness of skin-layer, the problem allows analytical
solution for arbitrary boundary value problems. The analysis of dependence of
coefficients of transmission, reflection and absorbtion on angle incidence,
thickness of films and coefficient of specular reflection is carried out.Comment: 15 pages, 9 figure
Role of elastic scattering in electron dynamics at ordered alkali overlayers on Cu(111)
Scanning tunneling spectroscopy of p(2x2) Cs and Na ordered overlayers on
Cu(111) reveals similar line widths of quasi two-dimensional quantum well
states despite largely different binding energies. Detailed calculations show
that 50% of the line widths are due to electron-phonon scattering while
inelastic electron-electron scattering is negligible. A frequently ignored
mechanism for ordered structures, i.e., enhanced elastic scattering due to
Brillouin zone back folding, contributes the remaining width.Comment: 4 pages, 2 figures, 1 tabl
Model study of adsorbed metallic quantum dots: Na on Cu(111)
We model electronic properties of the second monolayer Na adatom islands
(quantum dots) on the Cu(111) surface covered homogeneously by the first Na
monolayer. An axially-symmetric three-dimensional jellium model, taking into
account the effects due to the first Na monolayer and the Cu substrate, has
been developed. The electronic structure is solved within the local-density
approximation of the density-functional theory using a real-space multigrid
method. The model enables the study of systems consisting of thousands of
Na-atoms. The results for the local density of states are compared with
differential conductance () spectra and constant current topographs from
Scanning Tunneling Microscopy.Comment: 10 pages, 8 figures. For better quality figures, download
http://www.fyslab.hut.fi/~tto/cylart1.pd
Interaction of Electromagnetic S-Wave with a Metal Film Located Between Two Dielectric Mediums
Generalization of the theory of interaction of electromagnetic S-wave with a
metal film on a case of the film concluded between two dielectric environments
is developed.Comment: 13 pages, 10 figure
Role of bulk and surface phonons in the decay of metal surface states
We present a comprehensive theoretical investigation of the electron-phonon
contribution to the lifetime broadening of the surface states on Cu(111) and
Ag(111), in comparison with high-resolution photoemission results. The
calculations, including electron and phonon states of the bulk and the surface,
resolve the relative importance of the Rayleigh mode, being dominant for the
lifetime at small hole binding energies. Including the electron-electron
interaction, the theoretical results are in excellent agreement with the
measured binding energy and temperature dependent lifetime broadening.Comment: 4 pages, 3 figure
Simultaneous non-negative matrix factorization for multiple large scale gene expression datasets in toxicology
Non-negative matrix factorization is a useful tool for reducing the dimension of large datasets. This work considers simultaneous non-negative matrix factorization of multiple sources of data. In particular, we perform the first study that involves more than two datasets. We discuss the algorithmic issues required to convert the approach into a practical computational tool and apply the technique to new gene expression data quantifying the molecular changes in four tissue types due to different dosages of an experimental panPPAR agonist in mouse. This study is of interest in toxicology because, whilst PPARs form potential therapeutic targets for diabetes, it is known that they can induce serious side-effects. Our results show that the practical simultaneous non-negative matrix factorization developed here can add value to the data analysis. In particular, we find that factorizing the data as a single object allows us to distinguish between the four tissue types, but does not correctly reproduce the known dosage level groups. Applying our new approach, which treats the four tissue types as providing distinct, but related, datasets, we find that the dosage level groups are respected. The new algorithm then provides separate gene list orderings that can be studied for each tissue type, and compared with the ordering arising from the single factorization. We find that many of our conclusions can be corroborated with known biological behaviour, and others offer new insights into the toxicological effects. Overall, the algorithm shows promise for early detection of toxicity in the drug discovery process
Theory of inelastic lifetimes of surface-state electrons and holes at metal surfaces
After the early suggestion by John Pendry to probe unoccupied bands at
surfaces through the time reversal of the photoemission process, the
inverse-photoemission technique yielded the first conclusive experimental
evidence for the existence of image-potential bound states at metal surfaces
and has led over the last two decades to an active area of research in
condensed-matter and surface physics. Here we describe the current status of
the many-body theory of inelastic lifetimes of these image-potential states and
also the Shockley surface states that exist near the Fermi level in the
projected bulk band gap of simple and noble metals. New calculations of the
self-energy and lifetime of surface states on Au surfaces are presented as
well, by using the approximation of many-body theory.Comment: 17 pages, 7 figures, to appear in J Phys-Condens Ma
Second primary malignancies in patients with male breast cancer
An international multicentre study of first and second primary neoplasms associated with male breast cancer was carried out by pooling data from 13 cancer registries. Among a total of 3409 men with primary breast cancer, 426 (12.5%) developed a second neoplasia; other than breast cancer, a 34% overall excess risk of second primary neoplasia, affecting the small intestine (standardised incidence ratio, 4.95, 95% confidence interval, 1.35–12.7), rectum (1.78, 1.20–2.54), pancreas (1.93, 1.14–3.05), skin (nonmelanoma, 1.65, 1.16–2.29), prostate (1.61, 1.34–1.93) and lymphohaematopoietic system (1.63, 1.12–2.29). A total of 225 male breast cancers was recorded after cancers other than breast cancer, but an increase was found only after lymphohaematopoietic neoplasms. BRCA2 (and to some extent BRCA1) mutations may explain the findings for pancreatic and prostate cancers. Increases at other sites may be related to unknown factors or to chance. This large study shows that the risks for second discordant tumours after male breast cancer pose only a moderate excess risk
Nuclear receptors in vascular biology
Nuclear receptors sense a wide range of steroids and hormones (estrogens, progesterone, androgens, glucocorticoid, and mineralocorticoid), vitamins (A and D), lipid metabolites, carbohydrates, and xenobiotics. In response to these diverse but critically important mediators, nuclear receptors regulate the homeostatic control of lipids, carbohydrate, cholesterol, and xenobiotic drug metabolism, inflammation, cell differentiation and development, including vascular development. The nuclear receptor family is one of the most important groups of signaling molecules in the body and as such represent some of the most important established and emerging clinical and therapeutic targets. This review will highlight some of the recent trends in nuclear receptor biology related to vascular biology
Risks of second primary cancer among patients with major histological types of lung cancers in both men and women
10.1038/sj.bjc.6605616British Journal of Cancer10271190-1195BJCA
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