The Allure of the Few

Barry Brook reviews a new book on "Allee effects"--the processes by which small population sizes beget an accelerating decline in abundance and so hasten extinction

Influence of parental attitudes on substance consumption in adolescence

The aim of this quantitative cross-sectional study was to analyze the relationship between the perception of adolescents about their tendency to use psychoactive substances and their parents' attitudes. 487 Brazilian adolescents participated. For statistical analysis the Multinomial Logit Model was used, where the Stepwise method for selecting variables was applied. Tobacco, alcohol and marijuana were related to the variables of greatest influence on the use, abuse and dependence of these substances. Findings showed that an unloving father increases the possibility that the child becomes tobacco dependent (p = 0.001). An unloving mother is most likely to have a tobacco dependent child (p = 0.001). Father's control is a protective factor for experimenting with tobacco smoking (p = 0.023) and for marijuana dependence (p = 0.042). The relationship between substance consumption in adolescence and the perception young people have about their parents' attitudes was emphasized.El objetivo de este estudio transversal cuantitativo fue analizar la relación entre la percepción del adolescente sobre su tendencia al uso de sustancias psicoactivas y las actitudes de sus padres. Participaron 487 adolescentes brasileños. Para el análisis estadístico se utilizó el Modelo Logístico Multinomial, en el que se aplicaba el método Stepwise para la selección de variables. El tabaco, el alcohol y la marihuana se relacionaron con las variables de mayor influencia en el uso, abuso y dependencia. Se encontró que un padre poco cariñoso aumenta la posibilidad de que el niño sea dependiente del tabaco (p = 0.001), al igual que una madre poco afectuosa tiene más probabilidades de tener un hijo dependiente del tabaco (p = 0.001). El control del padre es un factor protector para la experimentación del tabaco (p = 0.023) y para la dependencia de la marihuana (p = 0.042). Se puso de relieve la relación entre el consumo de las drogas en la adolescencia y la percepción que los jóvenes tienen de las actitudes de sus padres.Este estudo transversal quantitativo objetivou analisar a relação entre a percepção do adolescente sobre as atitudes parentais e sua tendência ao uso de substâncias psicoativas. Participaram 487 adolescentes brasileiros. Para análise estatística foi utilizado o Modelo Logístico Multinomial, sobre o qual se aplicou o método Stepwise para seleção de variáveis. O tabaco, o álcool e a maconha foram relacionados com as variáveis de maior influência no uso, abuso ou dependência. Verificou-se que um pai pouco afetivo, aumenta a chance de o filho ser dependente de tabaco (p = 0.001). A mãe sendo pouco afetiva tem maior possibilidade de ter um filho dependente do tabaco (p = 0.001). O controle do pai é um fator protetivo para a experimentação do tabaco (p = 0.023) e para a dependência da maconha (p = 0.042). A relação entre o uso de drogas na adolescência e a percepção que o jovem tem das atitudes de seus pais ficou evidenciada

An aggregative response of the tropical Australian magpie goose (Anseranas semipalmata) to seasonal floodplains.

We describe the spatial aggregation of the magpie goose (Anseranas semipalmata) in relation to the dynamics of the ephemeral floodplains of northern Australia. Past broad-scale studies have linked geese to floodplains dominated by the sedge, Eleocharis dulcis, but the type of response has not been determined, nor the impact of predation on food plants. Moreover, departure thresholds are not known. We develop hypotheses on aggregation and departure and confront these with field data. Thus, from 2005–2007 we established two sites on the floodplains of Kakadu National Park (three 1-ha plots per site, six plots in total) and used for monthly, dry season bird counts. An airboat was used to collect data from each of the six plots, including sedge tubers and measures of water level and soil viscosity. Further, we built exclosures (three per site, six in total) to test the impact of herbivory on E. dulcis. Generalized linear models and information theory were used to test the strength of supporting evidence for alternate hypotheses. Geese showed a clear aggregative response to E. dulcis tubers, were forced to depart following floodplain drying and had a marked impact on E. dulcis tuber density. Despite this, there was no evidence of a negative-feedback mechanism between plant–herbivore populations, suggesting that the system is driven by extrinsic parameters (here rainfall)

Correlated emission and spin-down variability in radio pulsars

The recent revelation that there are correlated period derivative and pulse shape changes in pulsars has dramatically changed our understanding of timing noise as well as the relationship between the radio emission and the properties of the magnetosphere as a whole. Using Gaussian processes we are able to model timing and emission variability using a regression technique that imposes no functional form on the data. We revisit the pulsars first studied by Lyne et al. (2010). We not only confirm the emission and rotational transitions revealed therein, but reveal further transitions and periodicities in 8 years of extended monitoring. We also show that in many of these objects the pulse profile transitions between two well-defined shapes, coincident with changes to the period derivative. With a view to the SKA and other telescopes capable of higher cadence we also study the detection limitations of period derivative changes.Comment: 4 pages, 2 Figures, Proceedings of IAU Symposium 337 "Pulsar Astrophysics - The Next 50 Years" held at Jodrell Bank Observatory, UK Sept. 4-8 201

Fire impacts recruitment more than survival of small-mammals in a tropical savanna

The frequency and spatial patterning of fire for optimal biodiversity conservation is often poorly understood by managers, in part due to a lack of understanding of the mechanisms responsible for altering population dynamics of individual species. We investigated changes in the vital rates (survival and recruitment) of four small mammal species (three marsupials and one rodent) in a tropical savanna under four different experimental fire treatments applied at a landscape scale. Apparent survival declined in all fire treatments for only one of four small mammal species (northern brown bandicoot Isoodon macrourus). Recruitment was reduced in three of four species in multiple fire treatments. The suppression of recruitment in the northern brown bandicoot and the brushtail possum Trichosurus vulpecula populations was greatest immediately after the initial fire treatment was applied, compared to remaining treatment applications in successive years, possibly due to an elevated fire intensity as a result of higher initial fuel loads. The results suggest that higher intensity fire impacted recruitment more than survival for small mammals at this site. To assist fire managers to conserve small mammal populations in tropical savannas, we recommend fire regimes that optimise habitat resources for recruitment. This may be achieved by a reduction in fire frequency and managing fuel loads to prevent an increase in fire intensity

Compulsive Buying and Quality of Life: An Estimate of the Monetary Cost of Compulsive Buying Among Adults in Early Midlife

The aims of this study were to examine the associations between compulsive buying and quality of life and to estimate the monetary cost of compulsive buying for a cohort of men and women at mean age 43. Participants came from a community-based random sample of residents in two New York counties (N=548). The participants were followed from adolescence to early midlife. The mean age of participants at the most recent interview was 43.0 (SD=2.8). Fifty five percent of the participants were females. Over 90% of the participants were white. Linear regression analyses showed that compulsive buying was significantly associated with quality of life, despite controlling for relevant demographic and psychosocial factors. The estimated monetary cost of compulsive buying for this cohort was significant. The fact that the monetary cost of CB is not trivial suggests that individuals are both consciously and unconsciously plagued by their CB. The findings are important for interventionists and clinicians for cost-effective intervention and treatment programs