Influence of environmental variability and Emiliania huxleyi ecotypes on alkenone-derived temperature reconstructions in the subantarctic Southern Ocean.

Long-chain unsaturated alkenones produced by haptophyte algae are widely used as paleotemperature indicators. The unsaturation relationship to temperature is linear at mid-latitudes, however, non-linear responses detected in subpolar regions of both hemispheres have suggested complicating factors in these environments. To assess the influence of biotic and abiotic factors in alkenone production and preservation in the Subantarctic Zone, alkenone fluxes were quantified in three vertically-moored sediment traps deployed at the SOTS observatory (140°E, 47°S) during a year. Alkenone fluxes were compared with coccolithophore assemblages, satellite measurements and surface-water properties obtained by sensors at SOTS. Alkenone-based temperature reconstructions generally mirrored the seasonal variations of SSTs, except for late winter when significant deviations were observed (3-10 °C). Annual flux-weighted averages in the 3800 m trap returned alkenone-derived temperatures ~1.5 °C warmer than those derived from the 1000 m trap, a distortion attributed to surface production and signal preservation during its transit through the water column. Notably, changes in the relative abundance of E. huxleyi var. huxleyi were positively correlated with temperature deviations between the alkenone-derived temperatures and in situ SSTs (r = 0.6 and 0.7 at 1000 and 2000 m, respectively), while E. huxleyi var. aurorae, displayed an opposite trend. Our results suggest that E. huxleyi var. aurorae produces a higher proportion of C37:3 relative to C37:2 compared to its counterparts. Therefore, the dominance of var. aurorae south of the Subtropical Front could be at least partially responsible for the less accurate alkenone-based SST reconstructions in the Southern Ocean using global calibrations. However, the observed correlations were largely influenced by the samples collected during winter, a period characterized by low particle fluxes and slow sinking rates. Thus, it is likely that other factors such as selective degradation of the most unsaturated alkenones could also account for the deviations of the alkenone paleothermometer.

Full annual monitoring of Subantarctic Emiliania huxleyi populations reveals highly calcified morphotypes in high-CO2 winter conditions.

Ocean acidification is expected to have detrimental consequences for the most abundant calcifying phytoplankton species Emiliania huxleyi. However, this assumption is mainly based on laboratory manipulations that are unable to reproduce the complexity of natural ecosystems. Here, E. huxleyi coccolith assemblages collected over a year by an autonomous water sampler and sediment traps in the Subantarctic Zone were analysed. The combination of taxonomic and morphometric analyses together with in situ measurements of surface-water properties allowed us to monitor, with unprecedented detail, the seasonal cycle of E. huxleyi at two Subantarctic stations. E. huxleyi subantarctic assemblages were composed of a mixture of, at least, four different morphotypes. Heavier morphotypes exhibited their maximum relative abundances during winter, coinciding with peak annual TCO2 and nutrient concentrations, while lighter morphotypes dominated during summer, coinciding with lowest TCO2 and nutrients levels. The similar seasonality observed in both time-series suggests that it may be a circumpolar feature of the Subantarctic zone. Our results challenge the view that ocean acidification will necessarily lead to a replacement of heavily-calcified coccolithophores by lightly-calcified ones in subpolar ecosystems, and emphasize the need to consider the cumulative effect of multiple stressors on the probable succession of morphotypes.

The relationship between cannabis involvement and suicidal thoughts and behaviors.

BACKGROUND: In the present study, we examined the relationship between cannabis involvement and suicidal ideation (SI), plan and attempt, differentiating the latter into planned and unplanned attempt, taking into account other substance involvement and psychopathology. METHODS: We used two community-based twin samples from the Australian Twin Registry, including 9583 individuals (58.5% female, aged between 27 and 40). The Semi-Structured Assessment of the Genetics of Alcoholism (SSAGA) was used to assess cannabis involvement which was categorized into: (0) no cannabis use (reference category); (1) cannabis use only; (2) 1-2 cannabis use disorder symptoms; (3) 3 or more symptoms. Separate multinomial logistic regression analyses were conducted for SI and suicide attempt with or without a plan. Twin analyses examined the genetic overlap between cannabis involvement and SI. RESULTS: All levels of cannabis involvement were related to SI, regardless of duration (odds ratios [ORs]=1.28-2.00, p<0.01). Cannabis use and endorsing ≥3 symptoms were associated with unplanned (SANP; ORs=1.95 and 2.51 respectively, p<0.05), but not planned suicide attempts (p>0.10). Associations persisted even after controlling for other psychiatric disorders and substance involvement. Overlapping genetic (rG=0.45) and environmental (rE=0.21) factors were responsible for the covariance between cannabis involvement and SI. CONCLUSIONS: Cannabis involvement is associated, albeit modestly, with SI and unplanned suicide attempts. Such attempts are difficult to prevent and their association with cannabis use and cannabis use disorder symptoms requires further study, including in different samples and with additional attention to confounders.

Vulnerability of polar oceans to anthropogenic acidification: comparison of arctic and antarctic seasonal cycles.

Polar oceans are chemically sensitive to anthropogenic acidification due to their relatively low alkalinity and correspondingly weak carbonate buffering capacity. Here, we compare unique CO2 system observations covering complete annual cycles at an Arctic (Amundsen Gulf) and Antarctic site (Prydz Bay). The Arctic site experiences greater seasonal warming (10 vs 3°C), and freshening (3 vs 2), has lower alkalinity (2220 vs 2320 µmol/kg), and lower summer pH (8.15 vs 8.5), than the Antarctic site. Despite a larger uptake of inorganic carbon by summer photosynthesis, the Arctic carbon system exhibits smaller seasonal changes than the more alkaline Antarctic system. In addition, the excess surface nutrients in the Antarctic may allow mitigation of acidification, via CO2 removal by enhanced summer production driven by iron inputs from glacial and sea-ice melting. These differences suggest that the Arctic system is more vulnerable to anthropogenic change due to lower alkalinity, enhanced warming, and nutrient limitation.

Life events and borderline personality features: the influence of gene-environment interaction and gene-environment correlation.

BACKGROUND: Traumatic life events are generally more common in patients with borderline personality disorder (BPD) than in non-patients or patients with other personality disorders. This study investigates whether exposure to life events moderates the genetic architecture of BPD features. As the presence of genotype-environment correlation (rGE) can lead to spurious findings of genotype-environment interaction (G × E), we also test whether BPD features increase the likelihood of exposure to life events. METHOD: The extent to which an individual is at risk to develop BPD was assessed with the Personality Assessment Inventory - Borderline features scale (PAI-BOR). Life events under study were a divorce/break-up, traffic accident, violent assault, sexual assault, robbery and job loss. Data were available for 5083 twins and 1285 non-twin siblings. Gene-environment interaction and correlation were assessed by using structural equation modelling (SEM) and the co-twin control design. RESULTS: There was evidence for both gene-environment interaction and correlation. Additive genetic influences on BPD features interacted with the exposure to sexual assault, with genetic variance being lower in exposed individuals. In individuals who had experienced a divorce/break-up, violent assault, sexual assault or job loss, environmental variance for BPD features was higher, leading to a lower heritability of BPD features in exposed individuals. Gene-environment correlation was present for some life events. The genes that influence BPD features thus also increased the likelihood of being exposed to certain life events. CONCLUSIONS: To our knowledge, this study is the first to test the joint effect of genetic and environmental influences and the exposure to life events on BPD features in the general population. Our results indicate the importance of both genetic vulnerability and life events.

Heritability of borderline personality disorder features is similar across three countries.

BACKGROUND: Most of our knowledge about borderline personality disorder features has been obtained through the study of clinical samples. Although these studies are important in their own right, they are limited in their ability to address certain important epidemiological and aetiological questions such as the degree to which there is a genetic influence on the manifestation of borderline personality disorder features. Though family history studies of borderline personality disorder indicate genetic influences, there have been very few twin studies and the degree of genetic influence on borderline personality disorder remains unclear. METHOD: Data were drawn from twin samples from The Netherlands (n=3918), Belgium (n=904) and Australia (n=674). In total, data were available on 5496 twins between the ages of 18 and 86 years from 3644 families who participated in the study by completion of a mailed self-report questionnaire on borderline personality disorder features. RESULTS: In all countries, females scored higher than males and there was a general tendency for younger adults to endorse more borderline personality disorder features than older adults. Model-fitting results showed that additive genetic influences explain 42% of the variation in borderline personality disorder features in both men and women and that this heritability estimate is similar across The Netherlands, Belgium and Australia. Unique environmental influences explain the remaining 58% of the variance. CONCLUSION: Genetic factors play a role in individual differences in borderline personality disorder features in Western society.

Diagnostic efficiency of the Iowa personality disorder screen items in a nonclinical sample.

The diagnostic efficiency of the 11-item Iowa Personality Disorder Screen (IPDS; Langbehn et al., 1999) was evaluated in a nonclinical sample of young adults, 35% of whom met DSM-III-R criteria for a personality disorder, in a retrospective analysis of SIDP-R data. Results indicated that two IPDS item sets (i.e., combinations of items) produced hit rates of more than 80% along with good sensitivity, specificity, positive predictive power, and negative predictive power. Combined with the findings of Langbehn et al. (1999), these results suggest that the IPDS may be useful as a screening measure for personality disorder in both clinical and nonclinical populations.

Structural relations between borderline personality disorder features and putative etiological correlates.

This study assessed the structural relations between borderline personality disorder (BPD) features and purported etiological correlates. Approximately 5,000 18-year-old nonclinical young adults were screened for BPD features, and 2 cohorts of participants (total N = 421; approximately one half of whom endorsed significant borderline features) completed the laboratory phase of the study. Measures included self-report and interview-based assessments of BPD psychopathology, personality, psychopathology in biological parents, and childhood physical and sexual abuse. Significant relations between BPD features and purported etiological correlates of BPD were found. A multivariate model that included parental psychopathology, childhood abuse, and personality factors provided an adequate fit to the data and supported the contention that the personality traits disinhibition and negative affectivity underlie BPD features.

A structured interview for the assessment of the Five-Factor Model of personality: facet-level relations to the axis II personality disorders.

The Structured Interview for the Five-Factor Model (SIFFM; Trull & Widiger, 1997) is an 120-item semistructured interview that assesses both adaptive and maladaptive features of the personality traits included in the five-factor model of personality, or "Big Five." In this article, we evaluate the ability of SIFFM scores to predict personality disorder symptomatology in a sample of 232 adults (46 outpatients and 186 nonclinical college students). Personality disorder symptoms were assessed using the Personality Diagnostic Questionnaire-Revised (PDQ-R; Hyler & Rider, 1987). Results indicated that many of the predicted associations between lower-order personality traits and personality disorders were supported. Further, many of these associations held even after controlling for comorbid personality disorder symptoms. These findings may help inform conceptualizations of the personality disorders, as well as etiological theories and treatment.

Relationships of borderline features to parental mental illness, childhood abuse, Axis I disorder, and current functioning.

Although a number of studies have investigated single, putative etiological factors for borderline personality disorder (BPD), few studies have assessed the relations between multiple etiological factors and borderline features within the same study. Borderline features, parental psychopathology, childhood physical and sexual abuse, lifetime Axis I disorder, and current functioning were assessed in 65 nonclinical participants, a portion of which exhibited significant BPD features. Multivariate models were tested and results indicated that parental mental illness and lifetime Axis I disorder were significant and unique predictors of borderline scores. Borderline features accounted for significant variance in current functioning beyond what was accounted for by other predictors; borderline scores mediated the relations between lifetime Axis I disorder and current functioning.

The factor structure of the Personality Assessment Inventory-Borderline Features (PAI-BOR) Scale in a nonclinical sample.

We evaluated the fit of Morey's (1991) proposed 4-factor structure on Personality Assessment Inventory-Borderline Features Scale (PAI-BOR; Morey, 1991) items in a sample of approximately 5,000 nonclinical participants. The proposed model did not fit the data well. Results from a series of exploratory and confirmatory factor analyses suggested that a 6-factor model provided the best fit to the PAI-BOR item covariances.

A mesoscale phytoplankton bloom in the polar Southern Ocean stimulated by iron fertilization.

Changes in iron supply to oceanic plankton are thought to have a significant effect on concentrations of atmospheric carbon dioxide by altering rates of carbon sequestration, a theory known as the 'iron hypothesis'. For this reason, it is important to understand the response of pelagic biota to increased iron supply. Here we report the results of a mesoscale iron fertilization experiment in the polar Southern Ocean, where the potential to sequester iron-elevated algal carbon is probably greatest. Increased iron supply led to elevated phytoplankton biomass and rates of photosynthesis in surface waters, causing a large drawdown of carbon dioxide and macronutrients, and elevated dimethyl sulphide levels after 13 days. This drawdown was mostly due to the proliferation of diatom stocks. But downward export of biogenic carbon was not increased. Moreover, satellite observations of this massive bloom 30 days later, suggest that a sufficient proportion of the added iron was retained in surface waters. Our findings demonstrate that iron supply controls phytoplankton growth and community composition during summer in these polar Southern Ocean waters, but the fate of algal carbon remains unknown and depends on the interplay between the processes controlling export, remineralisation and timescales of water mass subduction.

Predictors of suggestibility and false-memory production in young adult women.

Recent controversy over memories retrieved in therapy has highlighted the importance of increasing our understanding of individual differences in suggestibility and false-memory production. The purpose of this laboratory study was to assess the ability of several clinically relevant variables (acquiescence, self-esteem, and negative affect) to predict the tendency to yield to suggestive questioning, to alter responses in the face of interpersonal criticism, or to produce false memories (in this study, false recall of implied words). Results indicated that acquiescence significantly predicted suggestibility, as did competence self-esteem scores, but global self-esteem and negative affect scores did not. False-memory production (i.e., false recall of implied words) was associated with higher levels of both acquiescence and negative affect, but the tendency to alter responses after criticism was not significantly predicted by any variable.

Inventory of Interpersonal Problems Personality Disorder scales: operating characteristics and confirmatory factor analysis in nonclinical samples.

Research involving clinical samples has demonstrated the utility of a 28-item personality disorder (PD) screening measure (Inventory of Interpersonal Problems--Personality Disorder scale [IIP-PD]) culled from the IIP in the prediction of the presence or absence of a PD (Pilkonis, Kim, Proietti, & Barkham, 1996). This article extends these diagnostic efficiency findings to nonclinical samples and presents additional data regarding the factor structure of the 28 IIP-PD items. Diagnostic efficiency statistics for the IIP-PD scale, calculated using both interview and self-report methods, support the utility of the IIP-PD scale as a screening tool for the presence or absence of a PD. High specificity estimates indicate that individuals who do not exceed Diagnostic and Statistical Manual of Mental Disorders (4th ed.; American Psychiatric Association, 1994) symptom thresholds rarely exceed the IIP-PD cutoff. Furthermore, a high negative predictive power (NPP) estimate derived using an interview-based diagnostic standard suggests that the IIP-PD scale accurately screens out individuals who do not have a PD. Finally, cross-validated confirmatory factor-analytic results involving items composing the 5 IIP PD subscales identified in previous research (Kim, Pilkonis, & Barkham, 1997) suggest that a measurement model with a single second-order factor (general PD) and 5 first-order factors (one representing each PD subscale) provided the best fit to the observed data compared to 2 other competing models.

Borderline personality disorder and substance use disorders: a review and integration.

The empirical literature on the comorbidity between borderline personality disorder (BPD) and substance use disorders (SUDs) is reviewed. BPD-SUD comorbidity data obtained from studies published from 1987 to 1997 document the frequent co-occurrence of these diagnoses. Methodological issues and theoretical models for understanding this co-occurrence are discussed. Finally, we present our conceptualization of the relations and interactions of the major factors influencing the development of BPD and contributing to the comorbidity between BPD and SUDs.

Family patterns of perfectionism: an examination of college students and their parents.

We examined patterns of perfectionism among college students and their biological parents in a sample of 188 undergraduates from intact families. Ratings (self vs. other) showed the greatest degree of convergence when daughters were either the target or the rater. Levels of self-oriented perfectionism in students were positively associated with the levels characterizing the same-sex parent, but unrelated (father-daughter) or negatively related (mother-son) to the levels characterizing the opposite-sex parent. Finally, parents' other-oriented perfectionism was not significantly related to students' socially prescribed perfectionism.

Two-year stability of borderline personality measures.

Two-year stability coefficients were computed for several measures of borderline personality disorder within a nonclinical sample (n = 65) that included individuals with significant borderline features. Overall, the stability coefficients were modest (r ranging from .28 to .62; intraclass correlations ranging from .26 to .62). Stability values for each of the self-report measures under study were higher than those for the interview-based measure of BPD features, and, in some cases, these values varied as a function of the prototypicality of the subsamples examined. Analyses conducted to identify moderator effects provided no evidence that the stability of BPD scores was moderated by change in personal distress level; however, changes in BPD self-report scores were related to changes in level of negative affectivity.

Relations of five-factor model antagonism facets with personality disorder symptomatology.

The Five-Factor Model of Personality (FFM) has been used to conceptualize personality disorders as maladaptive variants of normal personality traits. This study assessed the convergence of 6 lower order traits, or facets, of FFM agreeableness versus antagonism (trust, straightforwardness, altruism, compliance, modesty, and tender-mindedness) with antisocial, borderline, narcissistic, paranoid, and passive-aggressive personality traits. Interview-based scores for all of the antagonism facets except compliance demonstrated the expected relations with these personality disorder traits. Results for self-reported facet scores were less clearly supportive, only yielding convergence for straightforwardness and altruism with respect to antisocial traits. It is suggested that future investigations of the FFM, or other normal personality trait models, and personality disorder symptomatology include analyses at the lower order trait level.

Comparison of the big-five factor structure across samples of Chinese and American adults.

We compared the factor structure of Goldberg's (1992) 50-item Bipolar Rating Scale (50-BRS) in samples of Chinese (n = 198) and American (n = 303) students. Results confirmed the hypothesized five-factor pattern for the U.S. sample, and a simultaneous multisample confirmatory factor analysis showed that the same five-factor pattern fit the item covariances in the Chinese sample. High levels of internal consistency were found within each sample, and a high degree of congruency of corresponding item factor loadings was obtained across samples. Overall, results supported the potential utility of the Five-Factor Model and the 50-BRS for assessing personality dimensions in Chinese culture.