Fermi surface map of large-scale single-orientation graphene on SiO2

Large scale tetraoctylammonium-assisted electrochemical transfer of graphene grown on single-crystalline Ir(1 1 1) films by chemical vapour deposition is reported. The transferred samples are characterized in air with optical microscopy, Raman spectroscopy and four point transport measurements, providing the sheet resistance and the Hall carrier concentration. In vacuum we apply low energy electron diffraction and photoelectron spectroscopy that indicate transferred large-scale single orientation graphene. Angular resolved photoemission reveals a Fermi surface and a Dirac point energy which are consistent with charge neutral graphene.

Direct imaging of boron segregation at dislocations in B:diamond heteroepitaxial films

A thin film of heavily B-doped diamond has been grown epitaxially by microwave plasma chemical vapor deposition on an undoped diamond layer, on top of a Ir/YSZ/Si(001) substrate stack, to study the boron segregation and boron environment at the dislocations present in the film. The density and nature of the dislocations were investigated by conventional and weak-beam dark-field transmission electron microscopy techniques, revealing the presence of two types of dislocations: edge and mixed-type 45° dislocations. The presence and distribution of B in the sample was studied using annular dark-field scanning transmission electron microscopy and spatially resolved electron energy-loss spectroscopy. Using these techniques, a segregation of B at the dislocations in the film is evidenced, which is shown to be intermittent along the dislocation. A single edge-type dislocation was selected to study the distribution of the boron surrounding the dislocation core. By imaging this defect at atomic resolution, the boron is revealed to segregate towards the tensile strain field surrounding the edge-type dislocations. An investigation of the fine structure of the B-K edge at the dislocation core shows that the boron is partially substitutionally incorporated into the diamond lattice and partially present in a lower coordination (sp(2)-like hybridization).

High quality single atomic layer deposition of hexagonal boron nitride on single crystalline Rh(111) four-inch wafers

The setup of an apparatus for chemical vapor deposition (CVD) of hexagonal boron nitride (h-BN) and its characterization on four-inch wafers in ultra high vacuum (UHV) environment is reported. It provides well-controlled preparation conditions, such as oxygen and argon plasma assisted cleaning and high temperature annealing. In situ characterization of a wafer is accomplished with target current spectroscopy. A piezo motor driven x-y stage allows measurements with a step size of 1 nm on the complete wafer. To benchmark the system performance, we investigated the growth of single layer h-BN on epitaxial Rh(111) thin films. A thorough analysis of the wafer was performed after cutting in atmosphere by low energy electron diffraction, scanning tunneling microscopy, and ultraviolet and X-ray photoelectron spectroscopies. The apparatus is located in a clean room environment and delivers high quality single layers of h-BN and thus grants access to large area UHV processed surfaces, which had been hitherto restricted to expensive, small area single crystal substrates. The facility is versatile enough for customization to other UHV-CVD processes, e.g., graphene on four-inch wafers.

Mental disorders in young adulthood

BACKGROUND

The effect of mental disorders may be particularly detrimental in early adulthood, and information on mental disorders and their correlates in this age group is important.

METHOD

A questionnaire focusing on mental health was sent to a nationally representative two-stage cluster sample of 1863 Finns aged 19 to 34 years. Based on a mental health screen, all screen-positives and a random sample of screen-negatives were asked to participate in a mental health assessment, consisting of the Structured Clinical Interview for DSM-IV (SCID-I) interview and neuropsychological assessment. We also obtained case-notes from all lifetime mental health treatments. This paper presents prevalences, sociodemographic associations and treatment contacts for current and lifetime mental disorders.

RESULTS

Forty percent of these young Finnish adults had at least one lifetime DSM-IV Axis I disorder, and 15% had a current disorder. The most common lifetime disorders were depressive disorders (17.7%) followed by substance abuse or dependence (14.2%) and anxiety disorders (12.6%). Of persons with any lifetime Axis I disorder, 59.2% had more than one disorder. Lower education and unemployment were strongly associated with current and lifetime disorders, particularly involving substance use. Although 58.3% of persons with a current Axis I disorder had received treatment at some point, only 24.2% had current treatment contact. However, 77.1% of persons with a current Axis I disorder who felt in need of treatment for mental health problems had current treatment contact.

CONCLUSIONS

Mental disorders in young adulthood are common and often co-morbid, and they may be particularly harmful for education and employment in this age group.

SARS knowledge, perceptions, and behaviors: a comparison between Finns and the Dutch during the SARS outbreak in 2003

BACKGROUND

The SARS outbreak served to test both local and international outbreak management and risk communication practices.

PURPOSE

The study compares SARS knowledge, perceptions, behaviors, and information between Finns and the Dutch during the SARS outbreak in 2003.

METHOD

The participants of the study, who used a modified SARS Psychosocial Research Consortium survey, were drawn from Internet panels in Finland (n = 308) and the Netherlands (n = 373) in June 2003. Multiple logistic regression analyses were used to calculate odds ratios (with 95% confidence intervals) to compare Finns with the Dutch for various levels of perceptions and behaviors.

RESULTS

Adjusted for age, education, and income, Finns were more likely to be knowledgeable and worried about SARS as well as to have low perceived comparative SARS risk and poor personal efficacy beliefs about preventing SARS. Finns were also more likely than the Dutch to have high confidence in physicians on SARS issues but less likely to have received information from the Internet and have confidence in Internet information.

CONCLUSIONS

The study shed light on how two European populations differed substantially regarding lay responses to SARS. Understanding these differences is needed in formulating and executing communication and outbreak management.

Willingness to take travel-related health risks--a study among Finnish tourists in Asia during the avian influenza outbreak

BACKGROUND

Health risk perception and behavior of tourists during epidemics is a challenge for behavioral medicine.

PURPOSE

The purpose was to analyze associations of psychosocial factors and willingness to take health risks on holiday and business trips.

METHOD

Subjects (survey n = 338) were Finnish tourists visiting South-East Asia during the avian influenza epidemic of 2004. On holidays, 13.8%, and on business trips, 6.3% would take (rather) high risks, 14.1% reported having tendency to take health risks. Willingness to take health risks on both kinds of trips was lower among those +40 years old than those <40. Comparatively high risk-taking tendency and high perceived HIV risk were related to the increased willingness to take health risks on both kinds of trips.

RESULTS

On holidays, willingness to take health risks was related to trust in fate, and on business trips, this was also related to trust in God and less precautionary behavior of avoiding hand shaking, but also to higher estimation of other risks in life.

CONCLUSION

Younger travelers and those on holidays are willing to take more health risks than those who are older or on business trips. Travel advice during epidemics could be differentially targeted to different age groups and to holiday and business travelers.

Reentrant superconductivity in Nb/Cu1-xNix bilayers

We report on the first observation of a pronounced reentrant superconductivity phenomenon in a superconductor/ferromagnet layered system. The results were obtained using a superconductor/ferromagnetic-alloy bilayer of Nb/Cu(1-x)Ni(x). The superconducting transition temperature T(c) drops sharply with increasing thickness dCuNi) of the ferromagnetic layer, until complete suppression of superconductivity is observed at d(CuNi) approximately equal to 4 nm. Increasing the Cu(1-x)Ni(x) layer thickness further, superconductivity reappears at d(CuNi) > or =13 nm. Our experiments give evidence for the pairing function oscillations associated with a realization of the quasi-one-dimensional Fulde-Ferrell-Larkin-Ovchinnikov-like state in the ferromagnetic layer.

Performance of CVD diamond as an optically and thermally stimulated luminescence dosemeter

Diamond is a material with extreme physical properties. Its radiation hardness, chemical inertness and tissue equivalence qualify it as an ideal material for radiation dosimetry. In the present work, the optically stimulated luminescence (OSL) and thermoluminescence (TL) characteristics of a 10 microm thick CVD diamond (polycrystalline diamond films prepared by chemical vapor deposition) film were studied in order to test its performance as a beta radiation dosemeter. The TL response is composed of four main TL glow peaks; two of these are in the range of 150-200 degrees C and two additional peaks in the 250-400 degrees C temperature range. The integrated TL as a function of radiation dose is linear up to 100 Gy and increases with increasing dose exposure. The dose dependence of the integrated OSL exhibits a similar behavior. The observed OSL/TL behavior for the CVD diamond film clearly demonstrate its capability for applications in radiation dosimetry with special relevance in medical dosimetry owing to the diamond's intrinsic material properties.

Psychological risk factors of incidence of breast cancer: a prospective cohort study in Finland

BACKGROUND

Belief that depression and other psychological factors predict breast cancer is common, but there have been few prospective epidemiological studies on this relationship.

METHOD

The relationship between depression, personality traits, illness attitudes, life events and health history, and breast cancer risk was studied in a prospective, 6-9 year follow-up of a cohort study of 10892 Finnish women of 48-50 years of age at the baseline. Cancer cases were obtained from the Cancer Registry of Finland. Multivariate logistic regression analysis was performed controlling for socioeconomic factors, family history of cancer, parity, and health behaviours.

RESULTS

Breast cancer incidence in the cohort was 1.15 times the average in age group 50-59. There was no evidence of depression, trait anxiety, cynical distrust, or coping being significant predictors of breast cancer incidence.

CONCLUSION

In this cohort study with the 6-9 year follow-up, psychological factors such as depression, trait anxiety, cynical distrust, or coping did not increase breast cancer risk.

Extended defect related energy loss in CVD diamond revealed by spectrum imaging in a dedicated STEM

This article aims at investigations of the low EEL region in the wide band gap system diamond. The advent of the UHV Enfina electron energy loss spectrometer combined with Digital Micrograph acquisition and processing software has made reliable detection of absorption losses below 10 eV possible. Incorporated into a dedicated STEM this instrumentation allows the acquisition of spectral information via spectrum maps (spectrum imaging) of sample areas hundreds of nanometers across, with nanometers pixel sizes, adequate spectrum statistics and 0.3 eV energy resolution, in direct correlation with microstructural features in the mapping area. We aim at discerning defect related losses at band gap energies, and discuss different routes to simultaneously process and analyse the spectra in a map. This involves extracting the zero loss peak from each spectrum and constructing ratio maps from the intensities in two energy windows, one defect related and one at a higher, crystal bandstructure dominated energy. This was applied to the residual spectrum maps and their first derivatives. Secondly, guided by theoretical EEL spectra calculations, the low loss spectra were fitted by a series of gaussian distributions. Pixel maps were constructed from amplitude ratios of gaussians, situated in the defect and the unaffected energy regime. The results demonstrate the existence of sp2-bonded carbon in the vicinity of stacking faults and partial dislocations in CVD diamond as well as additional states below conduction band, tailing deep into the band gap, at a node in a perfect dislocation. Calculated EEL spectra of shuffle dislocations give similar absorption features at 5-8 eV, and it is thought that this common feature is due to sp2-type bonding.

Epitaxy of cubic boron nitride on (001)-oriented diamond

Cubic boron nitride (c-BN), although offering a number of highly attractive properties comparable to diamond, like hardness, chemical inertness and a large electronic bandgap, up to now has not found the attention it deserves. This mostly has to do with preparational problems, with easy chemical routes not available and, instead, the necessity to apply ion-bombardment-assisted methods. Hence, most of the c-BN samples prepared as thin films have been nanocrystalline, making the prospect of using this material for high-temperature electronic applications an illusion. Although heteroepitaxial nucleation of c-BN on diamond substrates has been demonstrated using the high-pressure-high-temperature technique, none of the low-pressure methods ever succeeded in the epitaxial growth of c-BN on any substrate. Here, we demonstrate that heteroepitaxial c-BN films can be prepared at 900 degrees C on highly (001)-oriented diamond films, formed by chemical vapour deposition, using ion-beam-assisted deposition as a low-pressure technique. The orientation relationship was found to be c-BN(001)[100]||diamond(001)[100]. High-resolution transmission electron microscopy additionally proved that epitaxy can be achieved without an intermediate hexagonal BN layer that is commonly observed on various substrates.

Two distinct groups of non-attenders in an organized mammography screening program

OBJECTIVE

To find out reasons for non-attendance and to study subgroup differences of the non-attenders in an organized mammography screening program.

DESIGN

Prospective for background and psychosocial factors, retrospective for reasons of non-attendance.

SETTING

Finnish screening based on personal first round invitations, with 89% attendance rate.

PARTICIPANTS

Four hundred thirty six women with both pre-screening response to socioeconomic and psychosocial measures, and post-screening response reporting reasons of non-attendance.

MAIN RESULTS

Most common single reason for non-attendance was previous recent mammogram (53%), but also reasons related to practical obstacles, worry and fear, knowledge and attitudes, and organization of screening were mentioned. Two distinct groups of non-attenders were found based on the reasons for non-attendance. Those who did not attend because a mammogram taken elsewhere (ELSE, n = 233) were urban, well-to-do women, who took care of their health by own initiation and felt more susceptible to breast cancer, and also expected mammogram to be painful. Other (real) non-attenders (REAL, n = 155) were less compliant with health recommendations and services, more socially isolated, depressed and anxious than ELSE. Level of depression among REAL was clearly higher (10.80) than the mean value (7.91, SD = 7.28) of the age group, and was also slightly above the cut-off score of 10 indicating mild or moderate depression. Trait anxiety was also markedly higher (40.18) than that of the same age group (37.76, SD = 8.95).

CONCLUSIONS

Further research should clarify determinants and consequences of depression and anxiety among real non-attenders. Knowledge gaps and attitudinal barriers among non-attenders require more targeted campaigns.

Psychosocial predictors of first attendance for organised mammography screening

OBJECTIVE

To study psychosocial predictors of attendance at an organised breast cancer screening programme.

SETTING

Finnish screening programme based on personal first round invitations in 1992-94, and with 90% attendance rate.

METHODS

Attenders (n = 946) belonged to a 10% random sample (n = 1680 women, age 50, response rate 64%) of the target population (n = 16,886), non-attenders (n = 641, 38%) came from the whole target population. Predictors were measured one month before the screening invitation. Measures included items for social and behavioural factors, Breast Cancer Susceptibility Scale, Illness Attitude Scale, Health Locus of Control Scale, Anxiety Inventory, and Depression Inventory. Univariate and multivariate logistic regression analyses were used to predict attendance.

RESULTS

Those most likely to attend were working, middle income, and averagely educated women, who had not had a mass mammogram recently, but who regularly visited gynaecologists, attended for Pap smear screening, practised breast self examination, and who did not smoke. Low confidence in their own capabilities in breast cancer prevention, overoptimism about the sensitivity of mammography, and perception of breast cancer risk as moderate were also predictive of attendance. Expectation of pain at mammography was predictive of non-attendance.

CONCLUSION

Mammography screening organised as a public health service was well accepted. A recent mammogram, high reliance on self control of breast cancer, and an expectation of pain at mammography deterred attendance at screening. Further information about these factors and health information on screening are needed.

Experimental pain thresholds and plasma beta-endorphin levels during exercise

Experimental pain thresholds (electrical intracutaneous finger and dental pulp stimulation) and plasma hormone levels (beta-endorphin, cortisol, and catecholamines) were measured in ten healthy sportive men before, during, and after progressively more strenuous physical exercise. In a double-blind study conducted on two different days, 20 mg of the opioid-antagonist naloxone or placebo was administered prior to exercise. A significant pain threshold elevation was found during exercise for finger (ANOVA, P less than 0.004) and dental pulp stimulation (P less than 0.01). Pain threshold elevation was most pronounced during maximal exertion, at which time the subjects reported the greatest subjective fatigue. Thresholds remained elevated 10-15 min after the end of exercise, and, 60 min after exercise, thresholds returned to baseline values. The subjective magnitude estimation of suprathreshold stimuli was significantly reduced (P less than 0.0001) 5-10 min after exercise. Plasma beta-endorphin, cortisol, and catecholamines increased significantly (P less than 0.0005, all values) during exercise. Plasma beta-endorphin levels did not correlate significantly with pain thresholds (r = -0.37, NS). Naloxone failed to affect pain thresholds, although beta-endorphin and cortisol increased significantly more (P less than 0.02) during exercise after naloxone. It is concluded that short-term, exhaustive physical exercise can evoke a transient elevation in pain thresholds. This exercise-induced elevation in pain threshold does not, however, appear to be directly related to plasma endorphin levels.