Extreme electron accumulation with sheet density greater than 10(13) cm(-2) is almost universally present at the surface of indium nitride (InN). Here, x-ray photoemission spectroscopy and secondary ...ion mass spectrometry are used to show that the surface Fermi level decreases as the Mg concentration increases, with the sheet electron density falling to below 10(8) cm(-2). Surface space-charge calculations indicate that the lowering of the surface Fermi level increases the density of unoccupied donor-type surface states and that these are largely compensated by Mg acceptors in the near-surface hole depletion region rather than by accumulated electrons. This is a significant step towards the realization of InN-based optoelectronic devices.
This study compares the sensitivities and specificities of three techniques for the detection of circulating epithelial cells in the blood of patients with breast cancer. The number of circulating ...epithelial cells present in the blood of 40 patients with metastatic breast cancer and 20 healthy volunteers was determined by: immunomagnetic separation (IMS) and laser scanning cytometry (LSC), cell filtration and LSC and a multimarker real-time RT-PCR assay. Numbers of cytokeratin-positive cells identified and expression of three PCR markers were significantly higher in the blood of patients with breast cancer than in healthy volunteers. Using the upper 95% confidence interval of cells detected in controls to determine positive patient samples: 30% of patients with metastatic breast cancer were positive following cell filtration, 48% following IMS, and 60, 45 and 35% using real-time RT-PCR for cytokeratin 19, mammaglobin and prolactin-inducible peptide. Samples were significantly more likely to be positive for at least one PCR marker than by cell filtration (83 vs 30%, P<0.001) or IMS (83 vs 48%, P<0.001). The use of a multimarker real-time RT-PCR assay was therefore found to be the most sensitive technique for the detection of circulating epithelial cells in the blood of patients with breast cancer.
Summary
The perennial weed, Cirsium arvense (creeping, Canada or Californian thistle), is notorious for its ability to tolerate defoliation by mowing, herbivores or herbicides. The tolerance of 36 ...genotypes of C. arvense was examined by establishing pairs of clonal replicates that were assigned to a clipped or unclipped treatment. Three clippings were applied from spring to early summer to simulate repeated mowing. The average final percentage reduction caused by the repeated clipping was 18%, 72%, 32% and 50% for shoot biomass, root biomass, number of shoots and shoot height respectively. While nearly all genotypes were negatively affected by clipping, some overcompensated, and achieved greater shoot biomass, number of shoots, or increased height than their unclipped counterparts. No genotype was able to overcompensate, or fully tolerate, the lost root biomass due to repeated clipping. Genetic variation for tolerance to defoliation was detected for the number of shoots, maximum shoot height and for relative height growth rate. For relative growth rate, significant genetic variation was not detected until after the third clipping event, indicating that genotypes were equally tolerant to a moderate degree of defoliation, but upon more severe defoliation, genetic differences were evident. Since repeated defoliation is a recommended control technique, selection for more tolerant genotypes is possible and should be considered for the management of this weed.
Summary Background As trials of 5 years of tamoxifen in early breast cancer mature, the relevance of hormone receptor measurements (and other patient characteristics) to long-term outcome can be ...assessed increasingly reliably. We report updated meta-analyses of the trials of 5 years of adjuvant tamoxifen. Methods We undertook a collaborative meta-analysis of individual patient data from 20 trials (n=21 457) in early breast cancer of about 5 years of tamoxifen versus no adjuvant tamoxifen, with about 80% compliance. Recurrence and death rate ratios (RRs) were from log-rank analyses by allocated treatment. Findings In oestrogen receptor (ER)-positive disease (n=10 645), allocation to about 5 years of tamoxifen substantially reduced recurrence rates throughout the first 10 years (RR 0·53 SE 0·03 during years 0–4 and RR 0·68 0·06 during years 5–9 both 2p<0·00001; but RR 0·97 0·10 during years 10–14, suggesting no further gain or loss after year 10). Even in marginally ER-positive disease (10–19 fmol/mg cytosol protein) the recurrence reduction was substantial (RR 0·67 0·08). In ER-positive disease, the RR was approximately independent of progesterone receptor status (or level), age, nodal status, or use of chemotherapy. Breast cancer mortality was reduced by about a third throughout the first 15 years (RR 0·71 0·05 during years 0–4, 0·66 0·05 during years 5–9, and 0·68 0·08 during years 10–14; p<0·0001 for extra mortality reduction during each separate time period). Overall non-breast-cancer mortality was little affected, despite small absolute increases in thromboembolic and uterine cancer mortality (both only in women older than 55 years), so all-cause mortality was substantially reduced. In ER-negative disease, tamoxifen had little or no effect on breast cancer recurrence or mortality. Interpretation 5 years of adjuvant tamoxifen safely reduces 15-year risks of breast cancer recurrence and death. ER status was the only recorded factor importantly predictive of the proportional reductions. Hence, the absolute risk reductions produced by tamoxifen depend on the absolute breast cancer risks (after any chemotherapy) without tamoxifen. Funding Cancer Research UK, British Heart Foundation, and Medical Research Council.
The use of sub-keV primary ion beams for SIMS depth profiling is growing rapidly, especially in the semiconductor area. The first challenge in this new branch of the technique was to invent equipment ...capable of obtaining high quality data with sufficient rapidity to be economically viable. After a brief historical introduction, these radical developments across instrument type are reviewed. The current challenge is to obtain a good enough understanding of the experimental process to obtain accurate, interpretable, data. The elementary requirements for this are described with emphasis on data density. Finally, the physical limitations such as atomic mixing and transient effects at the surface and interfaces are discussed. Extrapolation of profile shape as a function of beam energy, combined with the use of capped samples, is discussed as a potential part of the solution.
The interactions between low energy He
+ ions and a series of transition metal surfaces have been studied using co-axial impact collision ion scattering spectroscopy (CAICISS). Experimental data were ...collected from the Ni(110), Cu(100), Pd(111), Pt(111) and Au(111) surfaces using ion beams with primary energies between 1.5
keV and 4.0
keV. The shadow cone radii deduced from the experimental surface peak positions were found to closely match theoretical predictions. Data analysis was performed using both the FAN and Kalypso simulation codes, revealing a consistent requirement for a reduction of 0.252 in the screening length correction in the Molière approximation within the Thomas–Fermi (TFM) interaction potential. The adjustments of the screening length in the TFM potential, predicted by O'Connor, and the uncorrected Ziegler–Biersack–Littmark (ZBL) potential both yielded inaccurate results for all of the surfaces and incident energies studied. We also provide evidence that, despite their different computational methodologies, the FAN and Kalypso simulation codes generate similar results given identical input parameters for the analysis of 180° backscattering spectra.
To determine whether pretreatment clinical features and molecular markers, together with changes in these factors, can predict treatment response and survival in patients with primary operable breast ...cancer who receive neoadjuvant therapy.
Mitoxantrone, methotrexate (with or without mitomycin), and tamoxifen chemoendocrine therapy was administered to 158 patients before surgery. Clinical response was assessed after four cycles of treatment. Fine-needle aspiration cytology for estrogen receptor (ER), progesterone receptor (PgR), c-erbB-2, p53, bcl-2, Ki67, S-phase fraction (SPF), and ploidy were performed pretreatment and repeated on day 10 or day 21 after the first cycle of treatment.
Good clinical response (GCR, defined as complete response or minimal residual disease) was achieved in 31% of patients (49 of 158). Tumor size, nodal disease, response, ER, PgR, c-erbB-2, p53, bcl-2, Ki67, SPF, and ploidy were analyzed as predictors of survival. By univariate analysis, node-positive disease (P =.05), lack of ER (P <.05) and PgR (P <.05), and failure to attain GCR (P =.008) were associated with a significantly increased risk of relapse. A significantly increased risk of death was associated with node-positive disease (P =.02), lack of ER expression (P =.04), and failure to attain GCR. By multivariate analysis, GCR was an independent predictor for survival (P =.05). ER expression (P =.03), absence of c-erbB-2 (P =.03), and a decrease in Ki67 on day 10 or day 21 of the first cycle (P <.05) significantly predicted for subsequent GCR.
Molecular markers may be used to predict the likelihood of achieving GCR, which seems to be a valid surrogate marker for survival.
This paper discusses the use of secondary ion mass spectrometry in cultural heritage studies recently reported in the literature, and includes material on the analysis of pigments, glass and metals. ...Applications of depth profiling, imaging, speciation and the topic of ultra-low energy SIMS depth profiling are addressed.
The atomic structure of the Cu(100)–p(32×2)R45°–Sn surface has been studied using medium energy ion scattering (MEIS), co-axial impact collision ion scattering spectroscopy (CAICISS), low energy ...electron diffraction (LEED) and Auger electron spectroscopy (AES). The p(32×2)R45° reconstruction was observed with LEED following the deposition of 0.42ML of Sn from a Knudsen cell on to the clean Cu(100) surface. The existence of sub-surface Sn atoms was immediately ruled out by the lack of blocking dips in the MEIS Sn scattered yield. Previously reported Sn overlayer and Cu–Sn surface layer alloy models were tested against the medium and low energy ion scattering data, with the best fit realised following structural optimization of the surface alloy model proposed by Pussi K. Pussi et al., Surf. Sci. 549 (2004) 24. Different out-of-plane shifts were observed for Sn atoms depending on their proximity to the missing Cu row.
► Deposition of Sn on Cu(100) forms complex reconstructions at submonolayer coverage. ► p(32×2)R45° reconstruction studied with ion scattering and electron diffraction techniques. ► Structure found to be a surface alloy, closely matching the Pussi model.
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