An increase in N-Ras expression is associated with development of hormone refractory prostate cancer in a subset of patients

Protein expression of H, K and N-Ras was assessed in hormone sensitive and hormone refractory prostate tumour pairs from 61 patients by immunohistochemistry. Expression of H-Ras and K- Ras was not associated with any known clinical parameters. In contrast an increase in N-Ras membrane expression in the transition from hormone sensitive to hormone refractory prostate cancer was associated with shorter time to relapse (p=0.01) and shorter disease specific survival (p=0.008). In addition, patients with an increase in N-Ras membrane expression had lower levels of PSA at relapse (p=0.02) and expression correlated with phosphorylated MAP kinase (p=0.010) and proliferation index (Ki67, p=0.02). These results suggest that in a subgroup patients N-Ras expression is associated with development of hormone refractory prostate cancer via activation of the MAP kinase cascade

Atmosphere/soil exchange processes of importance for molecular soil sciences

Globally the atmosphere/soil exchange can be interpreted as part of the biogeochemical cycles describing the transport of main chemical elements and their gaseous compounds between the compartments of the geosphere. Approaches to monitor and analyze these transport processes are described. The paramount role of Earth’s life, the biosphere, in these processes is emphasized

Theoretical Study of Spin-dependent Electron Transport in Atomic Fe Nanocontacts

We present theoretical predictions of spintronic transport phenomena that should be observable in ferromagnetic Fe nanocontacts bridged by chains of Fe atoms. We develop appropriate model Hamiltonians based on semi-empirical considerations and the known electronic structure of bulk Fe derived from ab initio density functional calculations. Our model is shown to provide a satisfactory description of the surface properties of Fe nano-clusters as well as bulk properties. Lippmann-Schwinger and Green's function techniques are used together with Landauer theory to predict the current, magneto-resistance, and spin polarization of the current in Fe nanocontacts bridged by atomic chains under applied bias. Unusual device characteristics are predicted including negative magneto-resistance and spin polarization of the current, as well as spin polarization of the current for anti-parallel magnetization of the Fe nanocontacts under moderate applied bias. We explore the effects that stretching the atomic chain has on the magneto-resistance and spin polarization and predict a cross-over regime in which the spin polarization of the current for parallel magnetization of the contacts switches from negative to positive. We find resonant transmission due to dangling bond formation on tip atoms as the chain is stretched through its breaking point to play an important role in spin-dependent transport in this regime. The physical mechanisms underlying the predicted phenomena are discussed.Comment: 13 pages, 6 figures, Accepted for publication in Physical Review

Association between exposure to second-hand smoke and telomere length: cross-sectional study of 1303 non-smokers

Background: Both active smoking and second-hand smoke (SHS) are important risk factors for many age-related diseases. Active smoking is associated with shortened telomere length. However, whether SHS accelerates telomere attrition with age is uncertain. The aim of this study was to examine the association between SHS exposure and shortening by age of leukocyte telomere length among adult non-smokers. Methods: We undertook a cross-sectional study of the association between self-reported levels of SHS exposure and telomere length shortening per annum on a subgroup of participants from the Scottish Family Health Study. Inclusion was restricted to non-smokers aged ≥ 18 years, who had provided self-reported overall usual SHS exposure (total hours per week) and blood samples for telomere analysis. Linear regression models were used to compare the ratio of telomere repeat copy number to single copy gene number (T/S)by age according to SHS exposure. Results: Of the 1303 eligible participants, 779 (59.8%) reported no SHS exposure, 495 (38.0%) low exposure (1–19 h per week) and 29 (2.2%) high exposure (≥20 h per week). In the univariate linear regression analyses, relative T/S ratio declined with increasing age in all exposure groups. Telomere length decreased more rapidly with increasing age among those with high exposure to SHS [adjusted coefficient −0.019, 95% confidence interval (CI) −0.031- −0.007) when compared with both those with no exposure to SHS (adjusted coefficient −0.006, 95% CI −0.008- −0.004) (high vs no SHS: P = 0.010) and those with low exposure to SHS (adjusted coefficient −0.005, 95% CI −0.007- −0.003) (high vs low SHS: P = 0.005). Conclusions: Our findings suggest that high SHS exposure may accelerate normal biological ageing, and support efforts to protect the public from SHS exposure. Further studies on relevant mechanisms should be conducted

Inverse Magnetoresistance of Molecular Junctions

We present calculations of spin-dependent electron transport through single organic molecules bridging pairs of iron nanocontacts. We predict the magnetoresistance of these systems to switch from positive to negative with increasing applied bias for both conducting and insulating molecules. This novel inverse magnetoresistance phenomenon is robust, does not depend on the presence of impurities, and is unique to molecular and atomic nanoscale magnetic junctions. Its physical origin is identified and its relevance to experiment and to potential technological applications is discussed.Comment: 5 pages, 3 figures; published version Phys. Rev.

Characterization of microwave absorption in carbon nanotubes using resonance aperture transmission method

A new method to characterize microwave electromagnetic absorption of a bulk carbon nanotube material is proposed and experimentally evaluated in this paper. The method is based on the measurement of microwave transmission through a capacitive-resonator aperture in a conductive screen loaded with a CNT sample under test. This method allows to measure microwave permittivity and absorption of thin samples, several atomic layers to few micrometers thick, with linear dimensions much smaller than the wavelength of radiation in free space. This minimal sample requirement restricts the application of conventional microwave characterization methods such as free-space or waveguide permittivity characterization. It is demonstrated that the resonance E-field enhancement inside the CRA leads to strong EM interaction of the microwave E-field with the CNT sample under test thus enabling high sensitivity and dynamic range of the measurement procedure. Another advantage of the proposed technique over conventional non-resonance characterization methods is that in the resonance transmission band, the CRA operation is reflection-less which leads to a relatively simple qualitative algebraic de-embedding procedure of the material parameters based on the principle of energy conservation. The experimental microwave absorption data of the multiwall CNT samples are presented in the S frequency band (2-4GHz), demonstrating microwave absorption properties of the multiwall CNT ribbons

Optical Transitions in Highly Excited States: RF LOG Spectrum of XeI

Pulsed laser optogalvanic spectroscopy of diluted gases in a 32MHz radio frequency discharge (RF LOG) was applied to xenon in a pressure range from 0.01to several Torr. The optical transitions caused by exciting the products of the discharge with laser energies from 14,000to 17,000cm? have been recorded and assigned. At low pressures, most transitions originate in the 5d states, whereas at higher pressures those from the 6p and 6s\u27 states become dominant. Results indicate that (il) coupling and selection rules /),J. = O, ± 1 and /),K. = O, ± 1 provide the most appropriate description of the observed transitions to the lower n-states. However, some transitions with /),K. = ± 2 also possess considerable intensity for some higher angular momentum transitions (p-d, d-f). The low pressure spectra are dominated by the d-f transitions for which all series have been observed. An important feature of these series is that at high n values (n> 20) the oscillatory potential of the RF field starts to populate high angular momentum states and causes a substantial broadening of the transitions to these states. In addition, close to the ionization limit, field induced ionization can take place and, under certain conditions, this may cause certain high series members to disappear. The corresponding results are presented and discussed

Surface excitonic emission and quenching effects in ZnO nanowire/nanowall systems: limiting effects on device potential.

We report ZnO nanowire/nanowall growth using a two-step vapour phase transport method on a-plane sapphire. X-ray diffraction and scanning electron microscopy data establish that the nanostructures are vertically well-aligned with c-axis normal to the substrate, and have a very low rocking curve width. Photoluminescence data at low temperatures demonstrate the exceptionally high optical quality of these structures, with intense emission and narrow bound exciton linewidths. We observe a high energy excitonic emission at low temperatures close to the band-edge which we assign to the surface exciton in ZnO at ~ 3.366 eV, the first time this feature has been reported in ZnO nanorod systems. This assignment is consistent with the large surface to volume ratio of the nanowire systems and indicates that this large ratio has a significant effect on the luminescence even at low temperatures. The band-edge intensity decays rapidly with increasing temperature compared to bulk single crystal material, indicating a strong temperature-activated non-radiative mechanism peculiar to the nanostructures. No evidence is seen of the free exciton emission due to exciton delocalisation in the nanostructures with increased temperature, unlike the behaviour in bulk material. The use of such nanostructures in room temperature optoelectronic devices appears to be dependent on the control or elimination of such surface effects