The search for spontaneous edge currents in Sr2RuO4 mesa structures with controlled geometrical shapes

Scanning Hall microscopy has been used to search for spontaneous edge fields in geometrically shaped mesa structures etched into the ab surface of Sr2RuO4 single crystals in order to test recent theories of the direction of edge current flow as a function of facet orientation and band filling. We find no evidence for spontaneous edge fields in any of our mesa structures above our experimental noise floor of ± 25 mG. We do, however, observe pronounced vortex clustering at low fields and temperatures, consistent with the established semi-Meissner scenario whereby a long range attractive component to the vortex-vortex interaction arises due, for example, to the multiband nature of the superconductivity. We also see clear evidence for the formation of a square vortex lattice inside square mesa structures above 1.3 K. Our results are discussed in terms of recent relevant experimental results and theoretical predictions.

Probing the spiral magnetic phase in 6 nm textured erbium using polarised neutron reflectometry

We characterise the magnetic state of highly-textured, sputter deposited erbium for a film of thickness 6 nm. Using polarised neutron reflectometry it is found that the film has a high degree of magnetic disorder, and we present some evidence that the film's local magnetic state is consistent with bulk-like spiral magnetism. This, combined with complementary characterisation techniques, show that thin film erbium is a strong candidate material for incorporation into device structures.

Disaggregating the distal, proximal, and time-varying effects of parent alcoholism on children's internalizing symptoms

We tested whether children show greater internalizing symptoms when their parents are actively abusing alcohol. In an integrative data analysis, we combined observations over ages 2 through 17 from two longitudinal studies of children of alcoholic parents and matched controls recruited from the community. Using a mixed modeling approach, we tested whether children showed elevated mother- and child-reported internalizing symptoms (a) at the same time that parents showed alcohol-related consequences (time-varying effects), (b) if parents showed greater alcohol-related consequences during the study period (proximal effects), and (c) if parents had a lifetime diagnosis of alcoholism that predated the study period (distal effects). No support for time-varying effects was found; proximal effects of mothers' alcohol-related consequences on child-reported internalizing symptoms were found and distal effects of mother and father alcoholism predicted greater internalizing symptoms among children of alcoholic parents. Implications for the time-embedded relations between parent alcoholism and children's internalizing symptoms are discussed.

Externalizing symptoms among children of alcoholic parents: Entry points for an antisocial pathway to alcoholism

The authors examined heterogeneity in risk for externalizing symptoms in children of alcoholic parents, as it may inform the search for entry points into an antisocial pathway to alcoholism. That is, they tested whether the number of alcoholic parents in a family, the comorbid subtype of parental alcoholism, and the gender of the child predicted trajectories of externalizing symptoms over the early life course, as assessed in high-risk samples of children of alcoholic parents and matched controls. Through integrative analyses of 2 independent, longitudinal studies, they showed that children with either an antisocial alcoholic parent or 2 alcoholic parents were at greatest risk for externalizing symptoms. Moreover, children with a depressed alcoholic parent did not differ from those with an antisocial alcoholic parent in reported symptoms. These findings were generally consistent across mother, father, and adolescent reports of symptoms; child gender and child age (ages 2 through 17); and the 2 independent studies examined. Multialcoholic and comorbid-alcoholic families may thus convey a genetic susceptibility to dysregulation along with environments that both exacerbate this susceptibility and provide few supports to offset it.

Specifying the relations between affect and heavy alcohol use among young adults

Current reformulations of the tension reduction hypothesis posit that only a subset of vulnerable individuals are at risk for drinking in response to negative affect. To further specify this model, this study examined the types of mood and social contexts under which affect and alcohol use are associated. Participants were 74 college students who completed repeated assessments of mood, alcohol use, friendship quality, and social support. A complex pattern of findings supported the moderating influences of gender, friendship factors, and the timing of behavior (i.e., weekends vs. weekdays) on the relation between affect and alcohol use. Young adults with less intimate and supportive friendships, as compared with their peers, showed risk for greater drinking following relative elevations in sadness and hostility. Such drinking episodes, in turn, predicted subsequent elevations in these same negative moods the following week. Gender differences in such a cyclical pattern of affect and alcohol use were found to vary across differing emotional experiences. Recommendations for a more refined theory of affect and alcohol use are discussed.

The prospective relation between dimensions of anxiety and the initiation of adolescent alcohol use

Examined the relation between early anxiety symptomatology (generalized and separation) and initiation of alcohol use 4 years later in an epidemiological sample of 936 children (45% girls), assessed at ages 9, 11, and 13, while controlling for the effects of depression. Although earlier overall anxiety symptomatology was unrelated to later onset of drinking, children with early symptoms of generalized anxiety were found to be at increased risk for initiation of alcohol use, whereas children with early symptoms of separation anxiety were at decreased risk. The magnitude of these relations was equally strong for boys and girls. In addition, early depressive symptomatology was associated with increased risk for initiation of alcohol use in adolescence. Results indicate that it is important to consider specific dimensions of anxiety symptomatology when attempting to identify those individuals at risk for early initiation of alcohol use.

Specifying the relations between affect and heavy alcohol use among young adults

Current reformulations of the tension reduction hypothesis posit that only a subset of vulnerable individuals are at risk for drinking in response to negative affect. To further specify this model, this study examined the types of mood and social contexts under which affect and alcohol use are associated. Participants were 74 college students who completed repeated assessments of mood, alcohol use, friendship quality, and social support. A complex pattern of findings supported the moderating influences of gender, friendship factors, and the timing of behavior (i.e., weekends vs. weekdays) on the relation between affect and alcohol use. Young adults with less intimate and supportive friendships, as compared with their peers, showed risk for greater drinking following relative elevations in sadness and hostility. Such drinking episodes, in turn, predicted subsequent elevations in these same negative moods the following week. Gender differences in such a cyclical pattern of affect and alcohol use were found to vary across differing emotional experiences. Recommendations for a more refined theory of affect and alcohol use are discussed.

Linking remote sensing, land cover and disease

Land cover is a critical variable in epidemiology and can be characterized remotely. A framework is used to describe both the links between land cover and radiation recorded in a remotely sensed image, and the links between land cover and the disease carried by vectors. The framework is then used to explore the issues involved when moving from remotely sensed imagery to land cover and then to vector density/disease risk. This exploration highlights the role of land cover; the need to develop a sound knowledge of each link in the predictive sequence; the problematic mismatch between the spatial units of the remotely sensed and epidemiological data and the challenges and opportunities posed by adding a temporal mismatch between the remotely sensed and epidemiological data. The paper concludes with a call for both greater understanding of the physical components of the proposed framework and the utilization of optimized statistical tools as prerequisites to progress in this field.

Implications of early versus late onset of attention-deficit/hyperactivity disorder symptoms

OBJECTIVE

The current diagnostic criteria for attention-deficit/hyperactivity disorder (ADHD) require that symptoms emerge prior to age 7 in order for a formal diagnosis to be considered. However, this age-of-onset criterion (AOC) has recently been questioned on both theoretical and empirical grounds.

METHOD

Data from 4 annual waves of interviews with 9- to 16-year-olds from the Great Smoky Mountains Study were analyzed.

RESULTS

Confirming previous studies, a majority of youths who had enough symptoms to meet criteria for ADHD were reported to have first exhibited these symptoms prior to age 7. Early onset of ADHD symptoms was associated with worse clinical outcomes in youths with the combined subtype of ADHD but not youths with the inattentive subtype.

CONCLUSIONS

Findings support the continued inclusion of the AOC for the assessment of the combined but not necessarily the inattentive subtype of ADHD. Too few youths had a late onset of solely hyperactive-impulsive symptoms to evaluate the AOC for that group. However, regardless of the age of onset, youths who had elevated levels of ADHD symptoms were at increased risk for negative outcomes that may necessitate intervention.

The application of latent curve analysis to testing developmental theories in intervention research

The effectiveness of a prevention or intervention program has traditionally been assessed using time-specific comparisons of mean levels between the treatment and the control groups. However, many times the behavior targeted by the intervention is naturally developing over time, and the goal of the treatment is to alter this natural or normative developmental trajectory. Examining time-specific mean levels can be both limiting and potentially misleading when the behavior of interest is developing systematically over time. It is argued here that there are both theoretical and statistical advantages associated with recasting intervention treatment effects in terms of normative and altered developmental trajectories. The recently developed technique of latent curve (LC) analysis is reviewed and extended to a true experimental design setting in which subjects are randomly assigned to a treatment intervention or a control condition. LC models are applied to both artificially generated and real intervention data sets to evaluate the efficacy of an intervention program. Not only do the LC models provide a more comprehensive understanding of the treatment and control group developmental processes compared to more traditional fixed-effects models, but LC models have greater statistical power to detect a given treatment effect. Finally, the LC models are modified to allow for the computation of specific power estimates under a variety of conditions and assumptions that can provide much needed information for the planning and design of more powerful but cost-efficient intervention programs for the future.

Emotionality and self-regulation, threat appraisal, and coping in children of divorce

A model of the effects of children's temperament (negative and positive emotionality, impulsivity and attention focusing) on post-divorce threat appraisals, coping (active and avoidant), and psychological symptoms (depression and conduct problems) was investigated. The study utilized a sample of 223 mothers and children (ages 9 to 12 years) who had experienced divorce within the last two years. Evidence was found of direct effects of child-report negative emotionality on children's threat perceptions and of child-report positive emotionality and impulsivity on children's coping. Indirect effects of negative emotionality on active and avoidant coping through threat appraisal were found. Direct effects of the temperament variables on symptoms were also found. Cross group analyses indicated that the models were robust to age differences, but gender differences were found in the relation between negative emotionality and depression. The results of this study indicate that temperament and threat appraisals are important predictors of children's post-divorce symptoms, and that temperament is a predictor of children's appraisal and coping process.

Long-term prognostic value of preoperative dipyridamole thallium imaging and clinical indexes in patients with diabetes mellitus undergoing peripheral vascular surgery

The objective of this study is to assess the prognostic impact of preoperative dipyridamole thallium imaging and clinical variables on the long-term outcome of diabetic patients undergoing peripheral vascular surgery. Complete follow-up was obtained in 101 consecutive patients with diabetes mellitus undergoing routine dipyridamole thallium scintigraphy before vascular surgery (mean 4.2 +/- 3.2 years, range 1 month to 11 years). Low risk was defined by diabetes alone with a normal resting electrocardiogram. High risk was defined as a history of angina, myocardial infarction, congestive heart failure, or resting electrocardiogram abnormalities. There were 71 deaths in 98 patients discharged alive from the hospital (median survival 4.4 years). Age, the presence of resting electrocardiogram abnormalities, and an abnormal thallium scan were independent predictors of late death. After adjusting for age >70 years and thallium abnormalities, high-risk patients had a death rate 4.8 times (95% confidence interval 1.7 to 13.4, p <0.002) greater than low-risk patients. The presence of >2 reversible thallium defects was useful in further risk stratification of both low- and high-risk patients. Low-risk patients with >2 reversible defects had a median survival of 4.0 years compared with 9.4 years in those with < or =2 reversible defects (p <0.001). Similarly, high-risk patients with < or =2 reversible defects had an intermediate median survival rate of 4.7 years compared with 1.8 years in the group with >2 reversible defects (p <0.001). Therefore, advanced age and the presence of resting electrocardiographic or thallium abnormalities identifies a subset of diabetic patients with a poor long-term outcome after vascular surgery. Combined clinical and thallium variables may identify a population in whom intensive medical or surgical interventions may be warranted to reduce both perioperative and late cardiac events.

Pathways of risk for accelerated heavy alcohol use among adolescent children of alcoholic parents

The current study examined two questions. First, do internalizing symptoms and externalizing behavior each mediate the relations between parent psychopathology (alcoholism, antisocial personality disorder, and affective disorder) and growth in adolescent heavy alcohol use? Second, are there gender differences in these mediated pathways? Using latent curve analyses, we examined these questions in a high-risk sample of 439 families (53% children of alcoholic parents; 47% female). Collapsing across gender, adolescent-reported externalizing behavior mediated both the relation between parent alcoholism and growth in heavy alcohol use and the relation between parent antisociality and growth in heavy alcohol use. Parent-reported externalizing behavior only mediated the relation between parent antisociality and growth in heavy alcohol use in males. No support was found for internalizing symptoms as a mediator of these relations. Avenues are suggested for further exploring and integrating information about different mediating processes accounting for children of alcoholics' risk for heavy alcohol use.

The influence of changes in marital status on developmental trajectories of alcohol use in young adults

OBJECTIVE

Multiple group latent curve analysis was used to assess the impact of changes in marital status on alcohol use trajectories in young adults and to test if these effects varied across ethnicity and gender.

METHOD

Four years of data were obtained from a sample of young adults (N = 4,052; 54% male) drawn from the National Longitudinal Survey of Youth. Alcohol use and marital status were assessed once per year and covariates included age, gender, education and ethnicity.

RESULTS

Latent curve models indicated that there was an overall nonlinear negative alcohol use trajectory across the four time points and that becoming married was reliably associated with an added down-turn to this trajectory. Multiple group models indicated that there was an interaction between ethnicity and marital status in the prediction of alcohol growth trajectories, but there was no interaction with gender.

CONCLUSIONS

Becoming married for the first time exerted a unique effect on the overall developmental trajectory of alcohol use over time. This effect held for both ethnic groups but was reliably stronger for white compared to black respondents. This interaction may be attributable to lower levels of alcohol use reported by black respondents, or may be related to individual differences in reactivity to social influences by blacks relative to whites.

The relation between adolescent alcohol use and peer alcohol use: a longitudinal random coefficients model

Longitudinal latent growth models were used to examine the relation between changes in adolescent alcohol use and changes in peer alcohol use over a 3-year period in a community-based sample of 363 Hispanic and Caucasian adolescents. Both adolescent alcohol use and peer alcohol use were characterized by positive linear growth over time. Not only were changes in adolescent alcohol use closely related to changes in peer alcohol use, but the initial status on peer alcohol use was predictive of later increases in adolescent alcohol use and the initial status on adolescent alcohol use was predictive of later increases in peer alcohol use. These results are inconsistent with models positing solely unidirectional effects between adolescent alcohol use and peer alcohol use.

The relation of parent alcoholism to adolescent substance use: a longitudinal follow-up study

The current study tested parent alcoholism effects on growth curves of adolescent substance use and examined whether parent and peer influences, temperamental emotionality and sociability, and stress and negative affect could explain parent alcoholism effects. Longitudinal latent growth curve modeling showed that adolescents with alcoholic fathers, boys, and adolescents with drug-using peers had steeper growth in substance use over time than did adolescents without alcoholic fathers, girls, and adolescents without drug-using peers. Data were consistent with father's monitoring and stress as possible mediators of paternal alcoholism effects. However, the direct effects of paternal alcoholism on substance use growth remained significant even after including the hypothesized mediators in the model. This suggests that other (unmeasured) mediators are necessary to fully explain paternal alcoholism risk for adolescents' escalating substance use over time.

The relation between heavy alcohol use and bar patronage: a latent growth model

OBJECTIVE

Random effects latent growth (LG) models were used to study the relation between changes in heavy alcohol use and changes in the frequency of bar patronage over a 3-year period. Previous research has identified a close link between alcohol use and bar patronage, but these cross-sectional findings limit inferences about possible temporal ordering. LG models are highlighted and compared with the more traditional but restricted cross-lagged models.

METHOD

Three annual measures of heavy alcohol use and frequency of bar patronage were administered to a sample of 3071 adults (62% male) who participated in the National Longitudinal Study of Youch from 1982 to 1984. Background variables included age, gender, ethnicity and marital status.

RESULTS

Heavy alcohol use and bar patronage were characterized by negative longitudinal growth trajectories and there was significant individual variability in these changes over time. Changes in heavy alcohol use closely paralleled corresponding changes in bar patronage. Finally, the Time 1 measures of each construct were inversely predictive of subsequent changes over time in the second construct.

CONCLUSIONS

These findings suggest that heavy alcohol users tended to continue to patronize bars, and bar patronage tended to encourage continued heavy alcohol use. This relation was particularly strong for singles and males. Compared to more traditional cross-lagged models, LG modeling appears to be a much stronger analytic technique for studying growth over time. It is recommended that LG models be used for future studies of change in alcohol use over time.

A longitudinal study of parenting as a protective factor for children of alcoholics

OBJECTIVE

This study examined whether maternal parenting behaviors might serve to protect, or buffer, a child from the potentially negative effects associated with an alcoholic father.

METHOD

This hypothesis was tested with a community sample of adolescent children of alcoholics and a demographically matched comparison group of children with nonalcoholic parents (total N = 278, 55% male). Three dimensions of parenting were considered: monitoring of child behavior, consistency of discipline, and social support. These dimensions were used in both cross-sectional and longitudinal regression analyses to predict child externalizing symptomatology, alcohol use and drug use.

RESULTS

Cross-sectional results supported independent effects of parenting on child outcomes, but produced limited support for the buffering hypothesis. Longitudinal analyses revealed no prospective effects of parenting and no support for the buffering hypothesis.

CONCLUSIONS

Findings suggest that both parents influence child development outcomes, but that the influence of one parent does not depend upon the influence of the other parent.

The relation of parent alcoholism to adolescent substance use: a longitudinal follow-up study

The current study tested parent alcoholism effects on growth curves of adolescent substance use and examined whether parent and peer influences, temperamental emotionality and sociability, and stress and negative affect could explain parent alcoholism effects. Longitudinal latent growth curve modeling showed that adolescents with alcoholic fathers, boys, and adolescents with drug-using peers had steeper growth in substance use over time than did adolescents without alcoholic fathers, girls, and adolescents without drug-using peers. Data were consistent with father's monitoring and stress as possible mediators of paternal alcoholism effects. However, the direct effects of paternal alcoholism on substance use growth remained significant even after including the hypothesized mediators in the model. This suggests that other (unmeasured) mediators are necessary to fully explain paternal alcoholism risk for adolescents' escalating substance use over time.

Exploring the relationship between reflectance red edge and chlorophyll concentration in slash pine leaves

Chlorophyll concentration is related positively to the point of maximum slope in the reflectance spectra of leaves and this point is termed the red edge. The reflectance spectra of slash pine (Pinus elliottii Engelm.) needles were measured in the field and the chlorophyll concentrations of the same needles were measured in the laboratory. The measurement errors for red edge and chlorophyll concentration were determined to be 2.2 nm (3% of mean) and 0.35 mg g(-1) (19% of mean), respectively. The red edge-chlorophyll concentration relationship was strong (r(2) = 0.82, n = 152). A red edge-chlorophyll concentration relationship for n = 100 was used with red edge measurements to estimate chlorophyll concentration with an rms error of 0.31 mg g(-1) (17% of mean, n = 52). The entire red edge-chlorophyll concentration relationship for n = 152 was also used with red edge measurements to estimate the chlorophyll concentration of samples from an earlier experiment with an rms error of 0.47 mg g(-1) (30% of mean, n = 38). We conclude that measures of red edge can be used to estimate the chlorophyll concentration of detached needles in the field with an accuracy similar to that obtained by conventional laboratory measurements.

A comparison of mechanisms underlying substance use for early adolescent children of alcoholics and controls

The current study examined differences between children of alcoholics (COAs) and controls in parent monitoring, stress-negative affect, and temperament mechanisms underlying early adolescent substance use. Using structural equation modeling, we tested whether these mechanisms were equally predictive of substance use for both groups. We extended an earlier study that tested mediators of COA risk for substance use but did not examine COA status as a moderator of these mechanisms. Overall, we found no evidence of differential importance for COAs and non-COAs of the parent monitoring and negative affect mechanisms. Parental socialization and negative affect mechanisms significantly predicted adolescent substance use regardless of COA status. Differences did emerge regarding the effects of age and parent education on peer substance use and the effect of sociability on adolescent substance use.

Relation of parental alcoholism to early adolescent substance use: a test of three mediating mechanisms

The current study assessed 3 hypothesized mediating mechanisms underlying the relation between parental alcoholism and adolescent substance use. Using structural equation modeling, we analyzed data obtained from a large community sample of adolescent children of alcoholics and a demographically matched comparison group. Results suggested that parental alcoholism influenced adolescent substance use through stress and negative affect pathways, through decreased parental monitoring, and through increased temperamental emotionality (which was associated with heightened negative affect). Both negative affect and impaired parental monitoring were associated with adolescents' membership in a peer network that supported drug use behavior. The data did not support a link between parental alcoholism and temperamental sociability.