Provenance of long-travelled dust determined with ultra-trace-element composition: A pilot study with samples from New Zealand glaciers

We report high-precision inductively coupled plasma mass spectrometric (ICP-MS) compositional data for 39 trace elements in a variety of dust deposits, trapped sediments and surface samples from New Zealand and Australia. Dusts collected from the surface of alpine glaciers in the Southern Alps, New Zealand, believed to have undergone long-distance atmospheric transport from Australia, are recognizable on account of their overabundances of Pb and Cu with respect to typical upper crustal values. Long-travelled dust from Australia therefore scavenges these and other metals (e.g. Zn, Sb and Cd) from the atmosphere during transport and deposition. Hence, due to anthropogenic pollution, long-travelled Australian dusts can be recognized by elevated metal contents. The relative abundance of 25 other elements that are not affected by atmospheric pollution, mineral sorting (Zr and Hf) and weathering/solubility (alkali and earth alkali elements) reflects the geochemistry of the dust source sediment. As a result, we are able to establish the provenance of dust using ultra-trace-element chemistry at regional scale. Comparison of long-travelled dust chemistry with potential Australian sources shows that fits of variable quality are obtained. We propose that the best fitting potential source chemistry most likely represents the major dust source area. A binary mixing model is used to demonstrate that admixture of small quantities of local dust provides an even better fitting dust chemistry for the long-travelled dusts. Copyright (c) 2005 John Wiley & Sons, Ltd.

The consistency of extinction risk classification protocols

Systematic protocols that use decision rules or scores arc, seen to improve consistency and transparency in classifying the conservation status of species. When applying these protocols, assessors are typically required to decide on estimates for attributes That are inherently uncertain, Input data and resulting classifications are usually treated as though they arc, exact and hence without operator error We investigated the impact of data interpretation on the consistency of protocols of extinction risk classifications and diagnosed causes of discrepancies when they occurred. We tested three widely used systematic classification protocols employed by the World Conservation Union, NatureServe, and the Florida Fish and Wildlife Conservation Commission. We provided 18 assessors with identical information for 13 different species to infer estimates for each of the required parameters for the three protocols. The threat classification of several of the species varied from low risk to high risk, depending on who did the assessment. This occurred across the three Protocols investigated. Assessors tended to agree on their placement of species in the highest (50-70%) and lowest risk categories (20-40%), but There was poor agreement on which species should be placed in the intermediate categories, Furthermore, the correspondence between The three classification methods was unpredictable, with large variation among assessors. These results highlight the importance of peer review and consensus among multiple assessors in species classifications and the need to be cautious with assessments carried out 4), a single assessor Greater consistency among assessors requires wide use of training manuals and formal methods for estimating parameters that allow uncertainties to be represented, carried through chains of calculations, and reported transparently.

Evidence for retarded extinction of aversive learning in anxious children

The habituation to intense acoustic stimuli and the acquisition of differentially conditioned fear were assessed in 53 clinically anxious and 30 non-anxious control children and young adolescents. Anxious children tended to show larger electrodermal responses during habituation, but did not differ in blink startle latency or magnitude. After acquisition training, non-anxious children rated the CS + as more fear provoking and arousing than the CS- whereas the ratings of anxious children did not differ. However, anxious children rated the CS + as more fear provoking after extinction, a difference that was absent in non-anxious children. During extinction training, anxious children displayed larger blink magnitude facilitation during CS + and a trend towards larger electrodermal responses, a tendency not seen in nonanxious children. These data suggest that extinction of fear learning is retarded in anxious children. (c) 2005 Elsevier Ltd. All rights reserved.

Extinction times for a birth-death process with two phases

Many populations have a negative impact on their habitat or upon other species in the environment if their numbers become too large. For this reason they are often subjected to some form of control. One common control regime is the reduction regime: when the population reaches a certain threshold it is controlled (for example culled) until it falls below a lower predefined level. The natural model for such a controlled population is a birth-death process with two phases, the phase determining which of two distinct sets of birth and death rates governs the process. We present formulae for the probability of extinction and the expected time to extinction, and discuss several applications. (c) 2006 Elsevier Inc. All rights reserved.

The effects of assessment type on verbal ratings of conditional stimulus valence and contingency judgments: Implications for the extinction of evaluative learning

Recent research on causal learning found (a) that causal judgments reflect either the current predictive value of a conditional stimulus (CS) or an integration across the experimental contingencies used in the entire experiment and (b) that postexperimental judgments, rather than the CS's current predictive value, are likely to reflect this integration. In the current study, the authors examined whether verbal valence ratings were subject to similar integration. Assessments of stimulus valence and contingencies responded similarly to variations of reporting requirements, contingency reversal, and extinction, reflecting either current or integrated values. However, affective learning required more trials to reflect a contingency change than did contingency judgments. The integration of valence assessments across training and the fact that affective learning is slow to reflect contingency changes can provide an alternative interpretation for researchers' previous failures to find an effect of extinction training on verbal reports of CS valence.

The survey for ionization in neutral gas galaxies. II. The star formation rate density of the local universe

We derive observed H alpha and R-band luminosity densities of an H I-selected sample of nearby galaxies using the SINGG sample to be l'(H alpha) = (9.4 +/- 1.8) x 10(38) h(70) ergs s(-1) Mpc(-3) for H alpha and l'(R) = (4.4 +/- 9.7) x 10(37) h(70) ergs s(-1) angstrom(-1) Mpc(-3) in the R band. This R-band luminosity density is approximately 70% of that found by the Sloan Digital Sky Survey. This leads to a local star formation rate density of log ((rho)over dot(SFR) [M-circle dot yr(-1) Mpc(-3)]) = -1.80(-0.07)(+0.13)(random) +/- 0.03(systematic) + log (h(70)) after applying a mean internal extinction correction of 0.82 mag. The gas cycling time of this sample is found to be t(gas) = 7.5(-2.1)(+1.3) Gyr, and the volume-averaged equivalent width of the SINGG galaxies is EW(H alpha) = 28.8(-4.7)(+7.2) angstrom (21.2-3.5+4.2 angstrom without internal dust correction). As with similar surveys, these results imply that (rho)over dot(SFR)(z) decreases drastically from z similar to 1.5 to the present. A comparison of the dynamical masses of the SINGG galaxies evaluated at their optical limits with their stellar and H I masses shows significant evidence of downsizing: the most massive galaxies have a larger fraction of their mass locked up in stars compared with H I, while the opposite is true for less massive galaxies. We show that the application of the Kennicutt star formation law to a galaxy having the median orbital time at the optical limit of this sample results in a star formation rate decay with cosmic time similar to that given by the. (rho)over dot(SFR)(z) evolution. This implies that the (rho)over dot(SFR)(z) evolution is primarily due to the secular evolution of galaxies, rather than interactions or mergers. This is consistent with the morphologies predominantly seen in the SINGG sample.