An open-source high-frequency lock-in amplifier.

We present characterization of a lock-in amplifier based on a field programmable gate array capable of demodulation at up to 50 MHz. The system exhibits 90 nV/√Hz of input noise at an optimum demodulation frequency of 500 kHz. The passband has a full-width half-maximum of 2.6 kHz for modulation frequencies above 100 kHz. Our code is open source and operates on a commercially available platform.

Neutral Silicon-Vacancy Center in Diamond: Spin Polarization and Lifetimes.

We demonstrate optical spin polarization of the neutrally charged silicon-vacancy defect in diamond (SiV^{0}), an S=1 defect which emits with a zero-phonon line at 946 nm. The spin polarization is found to be most efficient under resonant excitation, but nonzero at below-resonant energies. We measure an ensemble spin coherence time T_{2}>100 µs at low-temperature, and a spin relaxation limit of T_{1}>25 s. Optical spin-state initialization around 946 nm allows independent initialization of SiV^{0} and NV^{-} within the same optically addressed volume, and SiV^{0} emits within the telecoms down-conversion band to 1550 nm: when combined with its high Debye-Waller factor, our initial results suggest that SiV^{0} is a promising candidate for a long-range quantum communication technology.

Electron paramagnetic resonance and photochromism of N3V0 in diamond.

The defect in diamond formed by a vacancy surrounded by three nearest-neighbor nitrogen atoms and one carbon atom, [Formula: see text], is found in the vast majority of natural diamonds. Despite [Formula: see text] being the earliest electron paramagnetic resonance spectrum observed in diamond, to date no satisfactory simulation of the spectrum for an arbitrary magnetic field direction has been produced due to its complexity. In this work, [Formula: see text] is identified in [Formula: see text]-doped synthetic diamond following irradiation and annealing. The [Formula: see text] spin Hamiltonian parameters are directly determined and used to refine the parameters for [Formula: see text], enabling the latter to be accurately simulated and fitted for an arbitrary magnetic field direction. Study of [Formula: see text] under excitation with green light indicates charge transfer between [Formula: see text] and [Formula: see text]. It is argued that this charge transfer is facilitated by direct ionization of [Formula: see text], an as-yet unobserved charge state of [Formula: see text].

Long-term follow-up of the Medical Research Council CLASICC trial of conventional versus laparoscopically assisted resection in colorectal cancer.

BACKGROUND: Laparoscopic resection is used widely in the management of colorectal cancer; however, the data on long-term outcomes, particularly those related to rectal cancer, are limited. The results of long-term follow-up of the UK Medical Research Council trial of laparoscopically assisted versus open surgery for colorectal cancer are presented. METHODS: A total of 794 patients from 27 UK centres were randomized to laparoscopic or open surgery in a 2:1 ratio between 1996 and 2002. Long-term follow-up data were analysed to determine differences in survival outcomes and recurrences for intention-to-treat and actual treatment groups. RESULTS: Median follow-up of all patients was 62·9 (interquartile range 22·9 - 92·8) months. There were no statistically significant differences between open and laparoscopic groups in overall survival (78·3 (95 per cent confidence interval (c.i.) 65·8 to 106·6) versus 82·7 (69·1 to 94·8) months respectively; P = 0·780) and disease-free survival (DFS) (89·5 (67·1 to 121·7) versus 77·0 (63·3 to 94·0) months; P = 0·589). In colonic cancer intraoperative conversions to open surgery were associated with worse overall survival (hazard ratio (HR) 2·28, 95 per cent c.i. 1·47 to 3·53; P < 0·001) and DFS (HR 2·20, 1·31 to 3·67; P = 0·007). In terms of recurrence, no significant differences were observed by randomized procedure. However, at 10 years, right colonic cancers showed an increased propensity for local recurrence compared with left colonic cancers: 14·7 versus 5·2 per cent (difference 9·5 (95 per cent c.i. 2·3 to 16·6) per cent; P = 0·019). CONCLUSION: Long-term results continue to support the use of laparoscopic surgery for both colonic and rectal cancer.

Applying interdisciplinary theory in the care of Aboriginal women's mental health.

This paper describes theories from various disciplines that are useful in conceptualizing and reflecting on the mental health of Aboriginal women. Critical social theory (sociology), Parse's human becoming theory (nursing) and ecological systems theory (developmental psychology) are considered valuable theories that aid in nursing praxis. These papers discuss how these different theoretical approaches are beneficial for achieving different goals and therefore provide important foundational underpinnings to challenging traditional assumptions that effect human behaviour and practice.

Demographic and geographic variations of oral health among African Americans based on NHANES III.

UNLABELLED: As efforts continue to improve the health of all US citizens, oral health must not be overlooked. Oral health is an integral part of overall health status and oral diseases are among the most prevalent of all health problems. OBJECTIVES: To describe the oral health status and oral health behaviors of African Americans. METHODS: The National Health and Nutrition Examination Survey (NHANES III) data set was used to examine a range of oral health indicators of African Americans with specific attention to demographic and geographic factors. The original data set consisted of 20,050 subjects, gathered through the use of complex, multi-stage, stratified and clustered sampling techniques. Only African Americans were included in this study which resulted in a sample of 5,616. Statistical analysis was conducted to allow the proper modeling of the complex, stratified, multistage survey design and sample weights of NHANES III. RESULTS: Sixty-two percent of respondents indicated that they only visit the dentist when needed and had no regular visitation schedule. Dental health was worse for those individuals who were poor, unemployed, and uninsured. Regional differences in dental care appeared with individuals living in the south reporting poorer dental health. CONCLUSIONS: The findings from this study are useful for identifying sociodemographic and geographic factors related to oral health status. The insights gained from this study illustrate the need for tailoring oral health promotion programmes and services to specific groups within the African American community because service utilisation and response patterns and perceptions may be different.

Determinants of social support among low-income mothers: a longitudinal analysis.

This study examined the reciprocal relationships between perceived mastery, stress, and three functional areas of social support: tangible support, informational support, and belongingness support. Data were collected during two face-to-face interviews with a sample of low-income, primarily African-American mothers, conducted approximately 1 year apart. Consistent with predictions, initial levels of mastery predicted higher subsequent levels of instrumental social supports (tangible and advice support), but were unrelated to belonging support. Conversely, initial levels of tangible support were predictive of later mastery. Perceived stress did not account for any additional variance in subsequent support, although initial levels of belonging support only did predict reduced stress at Time 2. Results suggest that successful attempts to garner instrumental supports is an important contributor to individuals' sense of self-efficacy, at the same time, self-efficacy leads to more successful use of existing social support systems. These findings point to the importance of having both available tangible support networks as well as close emotional supports for low-income parents. The importance of using longitudinal, multidimensional analyses to better understand the social support process is discussed.

Statewide Tuskegee Alliance for clinical trials. A community coalition to enhance minority participation in medical research.

BACKGROUND: Cancer mortality rates for all sites are nearly 2.5 times greater for African-Americans compared with whites. In addition, there are data implying that cancer treatment outcomes for minorities are unfavorable compared with whites. Whether this is due to poor access to health care or a biologic property of malignancies occurring in specific populations remains to be determined. Because of these unknown factors, targeting minorities for clinical trials may contribute toward the reduction of the overall morbidity and mortality associated with specific cancers. METHODS: The current study describes the establishment of a genuine collaborative partnership between the targeted minority community and clinical investigators at the University of Alabama at Birmingham. This partnership was formed for the purpose of identifying strategies that would enhance the accrual and retention of minority participants into current and future cancer prevention and control trials. Focus groups and key informant interviews were conducted to ascertain the community's perception of participating in clinical trials. RESULTS: The majority of focus group participants were unclear regarding the nature of clinical trials. Participants indicated that they would participate in research studies if they received adequate information regarding the purpose and benefits of the study, and if the charge came from a pastor or physician. Barriers to participation included time commitments, family obligations, whether blood was involved, and past experiences. The majority of the participants indicated that their knowledge of the Tuskegee Syphilis Study did not influence their decision to participate in research. A major outcome of the conference was the formation of the Statewide Tuskegee Alliance Coalition. The planning coalition decided to continue their efforts to work with communities and promote cancer awareness among minorities. After the conference, the coalition conducted several meetings and in July 1998, 1 year after the conference, the coalition selected a chair, co-chair, and a formal name for the organized group. CONCLUSIONS: The planning, development, and implementation of this conference provided a valuable experience for researchers and community members. It was discovered that community involvement in the early phase of this project contributed to its success. Furthermore, the partnership that developed between researchers (academic institutions) and communities successfully provided an infrastructure that supported the interest of both groups.

The Children's PTSD Inventory: development and reliability.

Information involving the development of the DSM-IV version of the Children's PTSD Inventory is described. Independent ratings by highly experienced judges denote that the instrument encompassed the universe of definition that it was intended to measure (i.e., the DSM-IV criteria for PTSD). The instrument was administered to 82 traumatized and 22 nontraumatized youths at Bellevue Hospital. Moderate to high Cronbach alphas (.53-.89) were evident at the subtest level. An alpha of .95 was evident at the diagnostic level. In terms of inter-rater reliability, 98.1% agreement was evident at the diagnostic level. Inter-rater intraclass correlation coefficients (ICCs) ranged from .88 to .96 at the subtest level and .98 at the diagnostic level. Good to excellent kappas (.66-1.00) were reported for inter-rater reliability at the subtest level. An inter-rater reliability kappa of .96 was evident at the diagnostic level. In terms of test-retest reliability, 97.6% agreement was evident at the diagnostic level. Good to excellent test-retest kappas (.66-1.00) and ICCs (.66-.94) were observed. A test-retest kappa of .91 and an ICC of .88 was observed at the diagnostic level.

Outcomes of single versus multiple trauma exposure in a screening sample.

Most studies ignore prior trauma exposure when evaluating outcomes of target events. This study explored symptom severity associated with different types of traumatic experiences occurring alone and with multiple exposure. The Stressful Life Events Screening Questionnaire categorized 1,909 sophomore women into groups including no trauma exposure, exposure to a serious non-Criterion A event only, exposure to several unique noninterpersonal and interpersonal events, and exposure to multiple interpersonal events. Women with noninterpersonal trauma did not differ from those without trauma on the Trauma Symptom Inventory. Only interpersonal trauma and non-Criterion A events were associated with elevated symptoms; multiple-exposure participants had significantly higher symptoms than all other groups. Complex trauma histories should be accounted for, even in studies of one target event.

Assessing the health attitudes, beliefs, and behaviors of African Americans attending church: a comparison from two communities.

Public health officials and researchers continue to be increasingly concerned about the health of populations of color, especially African Americans. A survey was administered in African American churches in two communities (Wichita, KS and Tuscaloosa, AL) to gather information concerning health behaviors and beliefs and to design interventions that might improve their health status. The study examined the homogeneity of attitudes, beliefs, and behaviors across these samples and to determine the readiness to change using the Transtheoritical Model. Individuals completed a 33-item survey: 6 demographic questions, 12 health behavior questions, 8 health belief questions, 3 church attendance questions, and 4 church-based health promotion program questions. The total sample consisted of 429 respondents. The results showed that 93% of respondents have had their blood pressure checked in the past 2 years. While only 44% indicated eating a high fiber diet during the week. Thirty percent of respondents indicated that their health was dependent on fate or destiny. The findings from this study confirm that among both samples that health attitudes, beliefs, and behaviors need to be changed to lower the risk of certain diseases and disorders. The findings also indicate that both samples have similar beliefs about health that may have important implications for disseminating information to the community. Innovative and culturally sensitive programs are needed in the African American community if disparities in health are to diminish.

Predictors and outcomes of posttraumatic stress disorder in World War II veterans exposed to mustard gas.

Current posttraumatic stress disorder (PTSD) associated with participation in secret military tests of mustard gas during World War II was assessed in 363 male military veterans who were randomly sampled from a registry developed by the Department of Veterans Affairs. Current prevalence was 32% for full PTSD and 10% for partial PTSD. Prevalence of PTSD varied as a function of risk and protective factors, including volunteering, physical symptoms during the tests, and prohibited disclosure. Prediction of partial PTSD was weaker than prediction of full PTSD. Veterans with full PTSD reported poorer physical health, a higher likelihood of several chronic illnesses and health-related disability, greater functional impairment, and higher likelihood of health care use than those with no PTSD. Veterans with partial PTSD also had poorer outcomes than did veterans with no PTSD in a subset of these domains. There is discussion of the traumatic elements of experimental mustard gas exposure, vulnerability to PTSD, and the relevance of these findings to understanding the broad range of outcomes associated with PTSD.

African-American attitudes regarding cancer clinical trials and research studies: results from focus group methodology.

Despite federal recommendations highlighting the need to include special population groups (mainly minorities and women) in clinical research, recruitment and retention of these groups present a great challenge to researchers. This paper describes a focus group study that was conducted to examine factors related to minority participation and retention in cancer clinical research studies. In 1996, the National Cancer Institute submitted a request for applicants to receive support for regional conferences. The purpose of the proposed conferences was to share current information and strategies to aid cancer clinical investigators in recruiting and retaining minority participants in clinical cancer research and to stimulate local/regional adaptations of these strategies. The University of Alabama at Birmingham (UAB), The University of Alabama, and Tuskegee University collaborated to respond to the request. Funding was granted by NCI for the regional conference in Alabama. The conference was held in Tuskegee, Alabama, the site of the infamous US Public Health Syphilis Study at Tuskegee. In planning for the conference, focus group sessions were conducted with African-American men and women who represented all regions of Alabama. The focus group information was used to identify important issues to be addressed at the conference.

Trauma history as a predictor of psychologic symptoms in women with breast cancer.

PURPOSE: To identify predictors of psychiatric problems in women with early-stage breast cancer. PATIENTS AND METHODS: One hundred sixty women with early-stage breast cancer were recruited from three treatment centers. They filled out self-report questionnaires, including a medical history and demographic survey, the Trauma History Questionnaire, Life Event Questionnaire, Brief Symptom Inventory, Beck Depression Inventory, and Duke-UNC Functional Social Support Questionnaire, and were evaluated using the Structured Clinical Interview for DSM-III-R. RESULTS: Hierarchical regression analyses indicated that four of five variable sets made a significant incremental contribution to outcome prediction, with 35% to 37% of the variance explained. Outcomes were predicted by demographic variables, trauma history variables, precancer psychiatric diagnosis, recent life events, and perceived social support. Cancer treatment variables did not predict outcome. CONCLUSION: The findings highlight the important roles of trauma history and recent life events in adjustment to cancer and have implications for screening and treatment.

Minority recruitment in clinical trials: a conference at Tuskegee, researchers and the community.

PURPOSE: This article describes the planning, implementation, and evaluation of a 2-day conference designed to examine the factors related to the participation of African Americans in cancer clinical trials. METHODS: Pre-conference formative evaluations (e.g., focus group discussions and key informant interviews with community leaders and health providers) were conducted in several rural and urban counties in the state of Alabama to determine African Americans' perceptions of participation in clinical research. The findings from these evaluations were used to develop a conference format and agenda. The 2-day conference included: (i) a pretest of African Americans' perceptions of cancer research, participation factors, and communication and recruitment issues; (ii) individual presentations high-lighting community leaders, church leaders, and researchers' perspectives regarding minority participation in research; (iii) working group discussions regarding the barriers and solutions to minority participation in research; and (iv) a posttest evaluation to measure changes in African Americans' perceptions of research. RESULTS: Several recruitment barriers and solutions were identified and reported by the working groups. Comparisons of the pretest and posttest measures showed significant (p > .05) and favorable shifts in the areas of perceptions of cancer research, participation factors, communication issues, and recruitment issues. Participation in the conference reflected a positive change in attitudes on these measures. However, the theme, "barriers that contributed to nonparticipation," did not show any significant changes during the two testing periods. The most critical lesson that resulted from this conference was the need for researchers and community members to have open dialogue about participation in research. CONCLUSIONS: This conference demonstrated that progress can be made when all parties are at the "table" and can be heard. In this model, community members proved to be valuable resources in providing researchers with information that was vital to the success of recruitment and retention studies and trials.

Human CYP1B1 Leu432Val gene polymorphism: ethnic distribution in African-Americans, Caucasians and Chinese; oestradiol hydroxylase activity; and distribution in prostate cancer cases and controls.

Cytochrome P4501B1 (CYP1B1) is involved in the activation of many carcinogens and in the metabolism of steroid hormones, including 17beta-oestradiol (E2) and testosterone. We report a significant difference in the allele frequencies of two point mutations in the coding region of the CYP1B1 gene among Caucasian (n = 189), African-American (n = 52) and Chinese (Linxian) (n = 109) populations. A (C to G) transversion at position 1666 in exon 3, which results in an amino acid substitution of Leu432 to Val, was present in African-Americans with an allele frequency for Va1432 of 0.75, in Caucasians of 0.43, and in Chinese of 0.17. A (C to T) transition at position 1719 in exon 3, with no amino acid change (Asp449), appeared to be closely linked with the Val432 variant. Results using human lung microsomal preparations from individuals with the CYP1B1Val/Val and CYP1B1Leu/Leu genotypes indicate that Val432 variant may be a high activity allele and thus may contribute to the interindividual differences in CYP1B1 activity. Because CYP1B1 is involved in hormone and carcinogen metabolism, and given the disparate rates of prostate cancer among ethnic groups, we also evaluated the association of the CYP1B1 Leu432Val polymorphism with prostate cancer risk in a pilot case-control study. Among Caucasians, 34% of men with cancer (n = 50) were homozygous for the Val432 polymorphism, while only 12% of matched control subjects (n = 50) had this genotype. These preliminary data indicate that genetic polymorphisms in CYP1B1 might play an important role in human prostate carcinogenesis.

Virus passage through track-etch membranes modified by salinity and a nonionic surfactant.

Why do viruses sometimes not pass through larger pores in track-etch filters? Increasing the salinity (0.8 to 160 mM Na+) decreased phiX174 and PRD1 passage through track-etch polycarbonate membranes (sodium dodecyl sulfate coated but not polyvinylpyrrolidone coated) and PRD1 passage through polyester membranes. Undiminished passage when 0.1% Tween 80 was added implied that nonionic virus adsorption occurred and indicated that high levels of salinity decreased virus passage by decreasing electrostatic repulsion that prevented adsorption.

Children's responses to a nuclear waste disaster: PTSD symptoms and outcome prediction.

OBJECTIVE: To examine the psychological impact of living near a nuclear waste disaster that involved ongoing threat of radioactive contamination. METHOD: Participants were an exposed sample (residence within a 5-mile radius of the nuclear plant) of 120 children (7-15 years old) and their parents and a nonexposed comparison sample of 60 children and their parents. Parent and self-ratings of the children's psychological functioning and posttraumatic stress disorder (PTSD) symptoms were obtained, along with cognitive variables. RESULTS: Minimal differences between the 2 samples were found. In the exposed sample, stress responses for the child self-reports showed several age group by gender interactions. Girls' PTSD symptoms tended to increase with age while boys' symptoms decreased, with intrusion showing the strongest effects. While child and parent PTSD symptom ratings were correlated, children reported approximately twice as many symptoms. Cognitive understanding increased with age and was greater in boys. Exposure and parent functioning significantly predicted outcome. CONCLUSIONS: Age and gender effects after disaster might best be explored as an interaction. While disaster effects were mild, the psychological health of the parents may be an important determinant of psychological health in children in this type of disaster.

The impact of a monensin controlled-release capsule on subclinical ketosis in the transition dairy cow.

An experiment was designed to examine subclinical ketosis in periparturient dairy cows and the antiketogenic effects of monensin. Subclinical ketosis was induced through a 10% feed restriction and was quantitatively determined using a blood beta-hydroxybutyrate (BHBA) threshold of 1200 mumol/L. Monensin decreased the BHBA concentration by 35% and increased the glucose concentration by 15%. No effect of monensin on milk production was detected, but rumen fermentation was altered. Monensin decreased the acetate to propionate ratio, decreased the butyrate concentration, and increased pH. The lower concentration of BHBA in blood and higher concentration of blood glucose in cows treated with a monensin controlled-release capsule decreased subclinical ketosis in early lactation cows.

Prospective social-psychological factors of adolescent smoking progression.

PURPOSE: To evaluate the ability of social-psychological risk factors to predict adolescent smoking behavior. METHODS: Nonsmoking adolescents (n = 4032) who participated in the 1989 and 1993 Teenage Attitudes and Practices Surveys (TAPS I) were selected for analyses. Four multivariate logistic models were used to examine (a) adolescents' smoking initiation, (b) adults' smoking initiation, (c) adolescents' progression to regular smoking, and (d) adults' progression to regular smoking. A series of social-psychological variables were measured. RESULTS: All four models were significant. However, no social-psychological factors were consistently significant in all four models, except white ethnicity. Data showed that social-psychological factors are less able to predict the transition from nonsmoking to experimental smoking than that from nonsmoking to regular smoking. CONCLUSIONS: Future prospective studies should measure both social-psychological and smoking acquisition factors at closer intervals to more accurately examine potential relationships.