Evaluation of uptake mechanisms of phosphate by Fe(III)(oxyhydr)oxides in Early Proterozoic oceanic conditions

Banded iron formations (BIF) are proxies of global dissolved inorganic phosphate (DIP) content in Precambrian marine waters. Estimates of Precambrian DIP rely on constraining the mechanisms by which Fe(III)(oxyhydr)oxides scavenge DIP in NaCl solutions mimicking elevated Precambrian marine Si and Fe(II) concentrations. The two DIP binding modes suggested for Early Proterozoic marine waters are 1) surface attachment on pre-formed Fe(III)(oxyhydr)oxides (adsorption), and 2) incorporation of P into actively growing Fe(III)(oxyhydr)oxides (coprecipitation) during the oxidation of Fe(II) to Fe(III)(oxyhydr)oxides in the presence of DIP. It has been suggested that elevated Si concentrations such as those suggested for Precambrian seawater, strongly inhibit adsorption of DIP in Fe(III)(oxyhydr)oxides, however recent coprecipitation experiments show that DIP is scavenged by Fe(III)(oxyhydr)oxides in the presence of Si, seawater cations and hydrothermal As. In this study we show that the DIP uptake onto Fe(III)(oxyhydr)oxides by adsorption is less than 5% of that by coprecipitation. Differences in surface attachment and the possibility of structural capture within the Fe(III)(oxyhydr)oxides are inferred from the robust influence Si has on DIP binding during adsorption, but inhibited for coprecipitation when As(III) and As(V) are present. The data imply that in the Early Proterozoic open oceans, Fe(III)(oxyhydr)oxides precipitated when deep anoxic Fe(II)-rich waters rose and mixed with the first permanently oxygenated ocean surface waters, caused DIP removal from surface waters through coprecipitation rather than adsorption. Local variations in DIP and perhaps even stratification of DIP in the oceans were likely created from the continuous removal of DIP from surface waters by Fe(III)(oxyhydr)oxides, and its partial release into the anoxic bottom waters and in buried sediments. In addition to a DIP famine, the selectivity for DIP over As(V) may have led to As enrichment in surface waters both of which would have most likely decreased the productivity of cyanobacteria and O2 production

Adolescent predictors of unemployment and disability pension across the life course: A longitudinal study of selection in 49 321 Swedish men

Objective: This study investigated the associations of adolescent cognitive ability, mental status and adaptability to school and work with unemployment from youth to mid-life. It also investigated the associations of youth unemployment with later unemployment and disability pension. Method: We used a cohort of 49 321 Swedish men, with information on cognitive ability, mental status, and school and personality characteristics in late adolescence in 1969. The information was linked to 32 years of annual administrative data to study predictors of unemployment and disability pension. Results: We found a strong and consistent association between cognitive ability and risk of unemployment, which was independent of other individual characteristics. Other notable independent risk factors were psychiatric diagnosis, contact with police or childcare authorities, smoking, risk use of alcohol, not being liked in school, and having been dismissed from or having quit a job due to unfair treatment. Unemployment before age 18 was found to be associated with unemployment across the life course, and also with disability pension, most of which was explained by individual characteristics. Conclusion: Certain individuals are more likely to be unemployed, and to be unemployed for more than one period, due to individual characteristics, which include cognitive ability, mental health, and labour-market related behaviour across the life course. However, people who become unemployed in youth have, regardless of their individual characteristics, an increased risk of becoming unemployed again. People who experience youth unemployment are also more likely to receive disability pension

A nearly optimal preconditioner for the Navier-Stokes equations

We present a preconditioner for the linearised Navier-Stokes equations which is based on the combination of fast transform approximation of an advection diffusion problem together with the recently introduced '$BFB^{T}$' preconditioner of Elman (SIAM J. Sci. Comput. 20 pp. 1299-1316, 1999). The resulting preconditioner when combined with an appropriate Krylov subspace iteration method yields the solution in a number of iterations which appears to be independent of the Reynolds number provided a mesh Peclet number restriction holds, and depends only mildly on the mesh size. The preconditioner is particularly appropriate for problems involving a primary flow direction

Reaction time and incident cancer: 25 years of follow-up of study members in the UK Health and Lifestyle Survey

<b>Objectives</b><p></p> To investigate the association of reaction time with cancer incidence.<p></p> <b>Methods</b><p></p> 6900 individuals aged 18 to 94 years who participated in the UK Health and Lifestyle Survey in 1984/1985 and were followed for a cancer registration for 25 years.<p></p> <b>Results</b><p></p> Disease surveillance gave rise to 1015 cancer events from all sites. In general, there was essentially no clear pattern of association for either simple or choice reaction time with cancer of all sites combined, nor specific malignancies. However, selected associations were found for lung cancer, colorectal cancer and skin cancer.<p></p> <b>Conclusions</b><p></p> In the present study, reaction time and its components were not generally related to cancer risk

Self-organization in systems of self-propelled particles

We investigate a discrete model consisting of self-propelled particles that obey simple interaction rules. We show that this model can self-organize and exhibit coherent localized solutions in one- and in two-dimensions.In one-dimension, the self-organized solution is a localized flock of finite extent in which the density abruptly drops to zero at the edges.In two-dimensions, we focus on the vortex solution in which the particles rotate around a common center and show that this solution can be obtained from random initial conditions, even in the absence of a confining boundary. Furthermore, we develop a continuum version of our discrete model and demonstrate that the agreement between the discrete and the continuum model is excellent.Comment: 4 pages, 5 figure

Collective behavior of interacting self-propelled particles

We discuss biologically inspired, inherently non-equilibrium self-propelled particle models, in which the particles interact with their neighbours by choosing at each time step the local average direction of motion. We summarize some of the results of large scale simulations and theoretical approaches to the problem

Psychosocial functioning and intelligence both partly explain socioeconomic inequalities in premature death. A population-based male cohort study

The possible contributions of psychosocial functioning and intelligence differences to socioeconomic status (SES)-related inequalities in premature death were investigated. None of the previous studies focusing on inequalities in mortality has included measures of both psychosocial functioning and intelligence.The study was based on a cohort of 49 321 men born 1949-1951 from the general community in Sweden. Data on psychosocial functioning and intelligence from military conscription at ∼18 years of age were linked with register data on education, occupational class, and income at 35-39 years of age. Psychosocial functioning was rated by psychologists as a summary measure of differences in level of activity, power of initiative, independence, and emotional stability. Intelligence was measured through a multidimensional test. Causes of death between 40 and 57 years of age were followed in registers.The estimated inequalities in all-cause mortality by education and occupational class were attenuated with 32% (95% confidence interval: 20-45%) and 41% (29-52%) after adjustments for individual psychological differences; both psychosocial functioning and intelligence contributed to account for the inequalities. The inequalities in cardiovascular and injury mortality were attenuated by as much as 51% (24-76%) and 52% (35-68%) after the same adjustments, and the inequalities in alcohol-related mortality were attenuated by up to 33% (8-59%). Less of the inequalities were accounted for when those were measured by level of income, with which intelligence had a weaker correlation. The small SES-related inequalities in cancer mortality were not attenuated by adjustment for intelligence.Differences in psychosocial functioning and intelligence might both contribute to the explanation of observed SES-related inequalities in premature death, but the magnitude of their contributions likely varies with measure of socioeconomic status and cause of death. Both psychosocial functioning and intelligence should be considered in future studies

Isostatic phase transition and instability in stiff granular materials

In this letter, structural rigidity concepts are used to understand the origin of instabilities in granular aggregates. It is shown that: a) The contact network of a noncohesive granular aggregate becomes exactly isostatic in the limit of large stiffness-to-load ratio. b) Isostaticity is responsible for the anomalously large susceptibility to perturbation of these systems, and c) The load-stress response function of granular materials is critical (power-law distributed) in the isostatic limit. Thus there is a phase transition in the limit of intinitely large stiffness, and the resulting isostatic phase is characterized by huge instability to perturbation.Comment: RevTeX, 4 pages w/eps figures [psfig]. To appear in Phys. Rev. Let