Ion yields and erosion rates for Si1−xGex(0x1) ultralow energy O2+ secondary ion mass spectrometry in the energy range of 0.25–1 keV

We report the SIMS parameters required for the quantitative analysis of Si1−xGex across the range of 0 ≤ x ≤ 1 when using low energy O2+ primary ions at normal incidence. These include the silicon and germanium secondary ion yield [i.e., the measured ion signal (ions/s)] and erosion rate [i.e., the speed at which the material sputters (nm/min)] as a function of x. We show that the ratio Rx of erosion rates, Si1−xGex/Si, at a given x is almost independent of beam energy, implying that the properties of the altered layer are dominated by the interaction of oxygen with silicon. Rx shows an exponential dependence on x. Unsurprisingly, the silicon and germanium secondary ion yields are found to depart somewhat from proportionality to (1−x) and x, respectively, although an approximate linear relationship could be used for quantification across around 30% of the range of x (i.e., a reference material containing Ge fraction x would give reasonably accurate quantification across the range of ±0.15x). Direct comparison of the useful (ion) yields [i.e., the ratio of ion yield to the total number of atoms sputtered for a particular species (ions/atom)] and the sputter yields [i.e., the total number of atoms sputtered per incident primary ion (atoms/ions)] reveals a moderate matrix effect where the former decrease monotonically with increasing x except at the lowest beam energy investigated (250 eV). Here, the useful yield of Ge is found to be invariant with x. At 250 eV, the germanium ion and sputter yields are proportional to x for all x

Characterization of the Noise in Secondary Ion Mass Spectrometry Depth Profiles

The noise in the depth profiles of secondary ion mass spectrometry (SIMS) is studied using different samples under various experimental conditions. Despite the noise contributions from various parts of the dynamic SIMS process, its overall character agrees very well with the Poissonian rather than the Gaussian distribution in all circumstances. The Poissonian relation between the measured mean-square error (MSE) and mean can be used to describe our data in the range of four orders. The departure from this relation at high counts is analyzed and found to be due to the saturation of the channeltron used. Once saturated, the detector was found to exhibit hysteresis between rising and falling input flux and output counts.Comment: 14 pages, 4 postscript figures, to appear on J. Appl. Phy

Exploring Student, Family, and School Predictors of Self-Determination Using NLTS2 Data

This study conducted secondary analysis of data from the National Longitudinal Transition Study-2 (NLTS2) to examine the degree to which student, family, and school constructs predicted self-determination outcomes. Multi-group structural equation modeling was used to examine predictive relationships between 5 student, 4 family, and 7 school constructs developed from NLTS2 data and self-determination outcomes (autonomy, psychological empowerment, and self-realization) across disability groups. The pattern of predictive relationship between the constructs and self-determination outcomes across disability groups was complex. Only one construct—self-concept—showed a positive predictive relationship with all three self-determination constructs across most disability groups. Implications of the complex pattern of findings for research and practice are discussed

Exploring Essential Characteristics of Self-Determination for Diverse Students Using Data From NLTS2

This study explored the impact of race/ethnicity on three of the four essential characteristics of self-determination—autonomy, self-realization, and psychological empowerment—directly assessed in the National Longitudinal Transition Study-2. Specifically, the impact of race/ethnicity was examined with six disability groups established in previous research: high incidence disabilities (learning disabilities, emotional disturbances, speech language impairments, and other health impairments), sensory disabilities (visual and hearing impairments), cognitive disabilities (autism, multiple disabilities, and deaf-blindness); intellectual disability, traumatic brain injury, and orthopedic impairments. Measurement equivalence was established across groups, but significant differences in the latent means, variances, and covariances were found suggesting a complex pattern of differences based on race/ethnicity within disability groups. Implications for future research and practice are discussed

Dopant Spatial Distributions: Sample Independent Response Function And Maximum Entropy Reconstruction

We demonstrate the use of maximum entropy based deconvolution to reconstruct boron spatial distribution from the secondary ion mass spectrometry (SIMS) depth profiles on a system of variously spaced boron $\delta$-layers grown in silicon. Sample independent response functions are obtained using a new method which reduces the danger of incorporating real sample behaviour in the response. Although the original profiles of different primary ion energies appear quite differently, the reconstructed distributions agree well with each other. The depth resolution in the reconstructed data is increased significantly and segregation of boron at the near surface side of the $\delta$-layers is clearly shown.Comment: 5 two-columne pages, 3 postscript figures, to appear in Phys. Rev. B1

New hurdles for translational research

New guidelines for the collection and use of human tissues for research will impose new requirements on researchers to seek ethical approval and patient consent. This extends to the use of surplus tissue, such as breast cancer excision biopsies, which, until recently, have been regarded as having been 'abandoned' by the patient. This article argues that some of these new constraints provide hurdles to translational research that are unnecessary for patient protection. This is particularly significant when emerging technologies are expected to elicit major advances in clinical cancer research

Very high Middle Miocene surface productivity on the U.S. mid-Atlantic shelf amid glacioeustatic sea level variability

The Miocene Climatic Optimum (MCO) provides important insights into how the climate system operates under elevated temperatures and atmospheric CO2 levels. Few western North Atlantic paleotemperature or paleoecological records exist from the MCO, despite their importance for understanding both regional and global climate dynamics. Here we present quantitative MCO paleoecological data from the western North Atlantic, specifically from the Baltimore Gas & Electric (BG&E) marine sediment core from southern Maryland, USA. We examine alkenones and planktic foraminifera and document the first sea surface temperature (SST) and productivity estimates for the MCO and the Middle Miocene Climate Transition (MMCT) from the continental shelf. Increased levels of planktic foraminifer species diversity and surface productivity accompany high sea level intervals of the MCO, indicating coastal upwelling. Cooling episodes correlate to unconformities in the BG&E core that reflect sea level lowstands; these and sedimentary cycles tie the record to eccentricity-paced Antarctic ice sheet growth and decay. This dynamic record not only captures the variability in SST, sea level and coastal productivity during the warm MCO and the transition to cooler global temperatures during the MMCT, but it also demonstrates the variability in local conditions within and between intervals of high sea level

What ‘incomparable Jewells Havens, and sure harbours are’: the remains of late 16th century Dover harbour and their wider significance

SUMMARY: During excavations undertaken for the Dover Western Dock Revival Scheme, Kent, UK, Archaeology South-East (ASE; UCL Institute of Archaeology) encountered substantial remains associated with the development of the port of Dover. Despite natural limitations, especially in the form of silting from the River Dour and longshore drift, Dover has historically been a strategic location in which to maintain a port. The remains presented here comprise a nationally significant waterfront revealed during the revival scheme; that is, the Tudor engineering commonly attributed to Sir Thomas Digges, overseen by the Privy Council and commissioned by Elizabeth I

Threat of Sexual Disqualification: The Consequences of Erectile Dysfunction and Other Sexual Changes for Gay and Bisexual Men With Prostate Cancer.

Gay and bisexual (GB) men with prostate cancer (PCa) have been described as an "invisible diversity" in PCa research due to their lack of visibility, and absence of identification of their needs. This study examined the meaning and consequences of erectile dysfunction (ED) and other sexual changes in 124 GB men with PCa and 21 male partners, through an on-line survey. A sub-sample of 46 men with PCa and seven partners also took part in a one-to-one interview. ED was reported by 72 % of survey respondents, associated with reports of emotional distress, negative impact on gay identities, and feelings of sexual disqualification. Other sexual concerns included loss of libido, climacturia, loss of sensitivity or pain during anal sex, non-ejaculatory orgasms, and reduced penis size. Many of these changes have particular significance in the context of gay sex and gay identities, and can result in feelings of exclusion from a sexual community central to GB men's lives. However, a number of men were reconciled to sexual changes, did not experience a challenge to identity, and engaged in sexual re-negotiation. The nature of GB relationships, wherein many men are single, engage in casual sex, or have concurrent partners, influenced experiences of distress, identity, and renegotiation. It is concluded that researchers and clinicians need to be aware of the meaning and consequences of sexual changes for GB men when designing studies to examine the impact of PCa on men's sexuality, advising GB men of the sexual consequences of PCa, and providing information and support to ameliorate sexual changes

Health-Related Quality of Life, Psychological Distress, and Sexual Changes Following Prostate Cancer: A Comparison of Gay and Bisexual Men with Heterosexual Men.

INTRODUCTION: Decrements in health-related quality of life (HRQOL) and sexual difficulties are a recognized consequence of prostate cancer (PCa) treatment. However little is known about the experience of gay and bisexual (GB) men. AIM: HRQOL and psychosexual predictors of HRQOL were examined in GB and heterosexual men with PCa to inform targeted health information and support. METHOD: One hundred twenty-four GB and 225 heterosexual men with PCa completed a range of validated psychosexual instruments. MAIN OUTCOME MEASURE: Functional Assessment of Cancer Therapy-Prostate (FACT-P) was used to measure HRQOL, with validated psychosexual measures, and demographic and treatment variables used as predictors. RESULTS: GB men were significantly younger (64.25 years) than heterosexual men (71.54 years), less likely to be in an ongoing relationship, and more likely to have casual sexual partners. Compared with age-matched population norms, participants in both groups reported significantly lower sexual functioning and HRQOL, increased psychological distress, disruptions to dyadic sexual communication, and lower masculine self-esteem, sexual confidence, and sexual intimacy. In comparison with heterosexual men, GB men reported significantly lower HRQOL (P = .046), masculine self-esteem (P < .001), and satisfaction with treatment (P = .013); higher psychological distress (P = .005), cancer related distress (P < .001) and ejaculatory concern (P < .001); and higher sexual functioning (P < .001) and sexual confidence (P = .001). In regression analysis, psychological distress, cancer-related distress, masculine self-esteem, and satisfaction with treatment were predictors of HRQOL for GB men (R2Adj = .804); psychological distress and sexual confidence were predictors for heterosexual men (R2Adj = .690). CONCLUSION: These findings confirm differences between GB and heterosexual men in the impact of PCa on HRQOL across a range of domains, suggesting there is a need for GB targeted PCa information and support, to address the concerns of this "hidden population" in PCa care