The theory developed here proposes that performance in cognitive tasks involves two distinct processes: acquisition of knowledge and cognitive control over knowledge already acquired. A conceptual and analytic framework is presented which allows for the disentanglement of knowledge and control, and for the quantification of each. Evidence from studies of multiple-cue probability learning, clinical judgment, and interpersonal conflict supports the theoretical usefulness of this framework and indicates that poor performance in cognitive tasks can often be attributed to incomplete cognitive control, rather than incomplete knowledge. The importance of cognitive feedback-• as opposed to traditional outcome feedback-for the development of cognitive control is illustrated.

No abstract

No abstract

Most studies of human inference have found that when the task requires that 5 utilize complex, nonlinear relations in order to make accurate inferences, performance is typically poor and improvement slow. It is proposed here that the poor performance observed in such tasks can be explicated if performance is partitioned into two components: acquisition and application of task knowledge. A conceptual and methodological framework is described which provides a statistical referent for each component and which facilitates their disentanglement. Empirical evidence supporting the usefulness of this framework is presented.

Analysis of the cognitive process of inductive inference should focus on inferences drawn from nonlinear as well as linear relations. Brunswik's probabilistic functionalism is demonstrated as a conceptual and methodological framework within which this question can be investigated. Analysis of Ss' utilization of nonlinear relations is illustrated by studying 30 Ss in the following task: (a) one cue related in a linear, the other in a nonlinear manner to a criterion, (b) the criterion partly, but not perfectly, predictable from either cue alone, and (c) the criterion perfectly predictable from appropriate utilization of both. Results indicate that Ss can improve both overall performance and nonlinear data utilization, and that performance varied with task-relevant instructions.

The reaction of ferrocene with molten imidazole at 150 °C yielded pale yellow crystals of composition [Fe3(imid)6(imidH)2] x . Crystals of [Fe3(imid)6(imidH)2] x are monoclinic, a = 10.5912(9), b = 12.958(2), c = 10.617(1) Å; β = 92.696(9)°; Z = 2; space group P21/c. The structure was solved by Patterson methods and refined by full-matrix least-squares procedures to R = 0.033 and R w = 0.031 for 2260 reflections with I ≥ 3σ(F 2). The structure consists of chains of tetrahedral iron centers cross-linked via octahedral iron ions to generate a 3-D array. All of the iron centers are bridged to four other metal centers via imidazolate ions, the two remaining (trans) coordination positions of the octahedral centers being occupied by neutral imidazole molecules. Magnetic susceptibilities on powdered samples were measured over the temperature range 2−300 K and at fields ranging from 0 to 55 000 G. The compound exhibits antiferromagnetic coupling along chains of tetrahedrally coordinated iron centers. A canted spin structure leads to weak ferromagnetism at temperatures below a magnetic phase transition temperature of 17 K. Upon cycling the applied magnetic field between +55 000 and −55 000 G at 4.8 K, a hysteresis loop was obtained with a remnant magnetization of 2500 cm3 G mol-1 and a coercive field of 200 G.

This report covers initial studies in the coaggregation of nickel (Ni2+) and lanthanide (Ln3+) metal ions to form complexes with interesting structural and magnetic properties. The tripodal amine phenol ligand H3tam (1,1,1-tris(((2-hydroxybenzyl)amino)methyl)ethane) is shown to be particularly accommodating with respect to the geometric constraints of both transition and lanthanide metal ions, forming isolable complexes with both of these ion types. In the solid-state structure of [Ni(H2tam)(CH3CN)]PF6.2.5CH3CN.0.5CH3OH (1), the Ni(II) center has a distorted octahedral geometry, with an N3O2 donor set from the [H2tam]- ligand and a coordinated solvent (acetonitrile) occupying the sixth site. The reaction of stoichiometric amounts of H3tam with the Ni(II) ion in the presence of lanthanide(III) ions provides [LnNi2(tam)2]+ cationic complexes which contain coaggregated metal ions. These complexes are isolable and have been characterized by a variety of analytical techniques, with mass spectrometry proving to be particularly diagnostic. The solid-state structures of [LaNi2(tam)2(CH3OH)1/2(CH3CH2OH)1/2(H2O)]ClO4.0.5CH3OH.0.5CH3CH2OH.4H2O (2), [DyNi2(tam)2(CH3OH)(H2O)]ClO4.CH3OH. H2O(6), and [YbNi2(tam)2(H2O)]ClO4.2.58H2O(9) have been determined. Each complex contains two octahedral Ni(II) ions, each of which is encapsulated by the ligand tam3- in an N3O3 coordination sphere; each [Ni(tam)]-unit caps the lanthanide(III) ion via bridging phenoxy oxygen donor atoms. In 2, La3+ is eight-coordinated, while in 6, Dy(III) is seven- (to "weakly eight-") coordinated, and Yb(III) in 9 has a six-coordination environment. The complexes are symmetrically different, 2 possessing C2 symmetry and 6 and 9 having C1 symmetry. Magnetic studies of 2, 6, and 9 indicate that antiferromagnetic exchange coupling between the Ni(II) and Ln(III) ions increases with decreasing ionic radius of Ln(III).

Hurricane Katrina made landfall on the Louisiana peninsula south of New Orleans on Aug 29, 2005. The resulting storm surge caused numerous levy breaches in the parishes of New Orleans as well as on the Louisiana peninsula. This study was conducted to determine the concentrations of inorganic and organic constituents in sediments and associated soils in New Orleans parishes and the Louisiana peninsula after the floodwaters had been removed and/or receded following Hurricane Katrina. A total of 46 sediment and soil samples were analyzed that were collected throughout New Orleans and the Louisiana peninsula. Approximately 20% of the sediment samples were analyzed, including shallow sediment samples from locations that included the top and beneath automobiles, in residential and commercial areas, and near refineries. Gasoline constituents, pesticides, and leachable heavy metals were analyzed using headspace gas chromatography/mass spectrometry (GC/MS), organic extraction GC/MS, and inductively coupled plasma/mass spectrometry, respectively. A significant number of samples had leachable As and Pb concentrations in excess of drinking water standards. The remaining metals analyzed (i.e., Cd, Cr, Cu, Hg, and V) generally had much lower leachable levels. Of the gasoline constituents, only benzene was observed above the limit of detection (of 5 microg/kg), with no samples observed as being above the method detection limits of 10 microg/kg. For the 18 pesticides analyzed, most were in the nondetectable range and all were in trace amounts that were orders of magnitude below regulatory guidelines.