String Block Vs Superblock Patterns of Dispersal in China

The superblock in China has become the dominant unit of urban planning, allowing for rapid urban growth while also meeting the needs of state and property developer alike. Kjersti Monson explains the conditions that have given rise to the superblock, while challenging it by proposing an alternative ‘stringblock’ approach, rooted more in collective culture and addressing the demands of the market-driven economy. Copyright © 2008 John Wiley & Sons, Ltd.     

Trait attributions: Relative validity, covariation with behavior, and prospect of future interaction.

Data obtained from 39 undergraduates suggest that the prospect of future interaction and the type of information available about an actor exerted considerable influence on the trait attributions offered by Ss. Attributions were more extremely dispositional, more valid, and more strongly related to subsequent behavioral tendencies when future interaction was anticipated than when it was not. Ss offered more extreme trait attributions when they were provided with behavioral information about the actors that warranted a dispositional inference than when they were not provided with such information. However, even when Ss were not provided with information that warranted a dispositional attribution, they still offered more extreme trait inferences when future interaction was anticipated than when it was not. Findings are interpreted in terms of three explanations for why the naive psychologist offers attributions. (30 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

"Social–Cognitive influences on change in aggression over time": Erratum.

Reports an error in the original article by S. K. Egan et al (Developmental Psychology, 1998 [Sep], Vol 34[5], 996–1006). On pages 1004–1005, the last sentence of the article should read as follows: "Given that we speculated that the effects of aversive treatment hinge crucially on factors such as timing and whether successful counterattacks occur, such observations, especially if supplemented with measures of social cognitions, might greatly enrich our understanding of how cognition and behavior jointly contribute to social development." The first line of text in the right-hand column on page 1005 should be deleted. (The following abstract of this article originally appeared in record 1998-10846-016.) This study examined whether social cognitions that have been assumed to influence aggression actually forecast change in aggressive habits over time. Participants were 189 3rd- through 7th-grade boys and girls; data on social cognitions and social behaviors were collected in the fall and spring of the school year. Aggression-encouraging cognitions assessed in the fall indeed promoted aggression over the school year, but such developments hinged critically on child sex and on initial (fall) levels of aggression and victimization. Results illustrate the principle that cognitions affect behavioral development mainly when the child's transactions with the social environment support the use of the cognitions as guides for behavior. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Improving nanoparticle dispersion and charge transfer in cadmium telluride tetrapod and conjugated polymer blends

The dispersion of CdTe tetrapods in a conducting polymer and the resulting charge transfer is studied using a combination of confocal fluorescence microscopy and atomic force microscopy (AFM). The results of this work show that both the tetrapod dispersion and charge transfer between the CdTe and conducting polymer (P3HT) are greatly enhanced by exchanging the ligands on the surface of the CdTe and by choosing proper solvent mixtures. The ability to experimentally probe the relationship between particle dispersion and charge transfer through the combination of AFM and fluorescence microscopy provides another avenue to assess the performance of polymer/semiconductor nanoparticle composites.     

Lifetime enhancement of ultrasmall fluorescent liquid polymeric film based optodes by diffusion-induced self-recovery after photobleaching

The major concern with optodes, especially miniaturized ones, has been their photobleaching limited lifetime. Liquid polymer [highly plasticized poly(vinyl chloride)] films are commonly used to prepare fluorescent optical fiber sensors. A major advantage is the ease of their fabrication. It is demonstrated here that, with proper choice of excitation power and illumination time, the sensor will completely recover itself from photobleaching after each measurement. This self-recovery is demonstrated on single-mode optical fibers with 80 microns diameter (3.1 microns active region) and on near-field scanning optical microscope pulled fiber tips with submicrometer diameter (250 nm active region). The single-mode optode can be used for 30,000 measurements with only a 5% signal loss at a signal/noise of > 66. This opens the way for prolonged ratiometric application of such optodes.     

Influence of carbon chain length on the synthesis and yield of fatty amine-coated iron-platinum nanoparticles

Iron oxide nanoparticles are among the most widely used and characterized magnetic nanoparticles. However, metal alloys such as superparamagnetic iron-platinum particles (SIPPs), which have better magnetic properties, are receiving increased attention. Scalable techniques to routinely synthesize SIPPs in bulk need further study. Here, we focus on the role played by the fatty amine ligand in the formation of the bimetallic FePt nanocrystal. More specifically, we compare the effect of varying lengths of fatty amine ligands on the shape, structure, uniformity, composition, and magnetic properties of the SIPPs. We synthesized SIPPs by employing a ‘green’ thermal decomposition reaction using fatty amine ligands containing 12 to 18 carbons in length. Greater fatty amine chain length increased the polydispersity, particle concentration, iron concentration, and the stability of the SIPPs. Additionally, longer reflux times increased the diameter of the particles, but decreased the iron concentration, suggesting that shorter reaction times are preferable. Fourier transform infrared spectroscopy of the SIPPs indicates that the ligands are successfully bound to the FePt cores through the amine group. Superconducting quantum interference device magnetometry measurements suggest that all of the SIPPs were superparamagnetic at room temperature and that SIPPs synthesized using tetradecylamine had the highest saturation magnetization. Our findings indicate that the octadecylamine ligand, which is currently used for the routine synthesis of SIPPs, may not be optimal. Overall, we found that using tetradecylamine and a 30-min reflux reaction resulted in optimal particles with the highest degree of monodispersity, iron content, stability, and saturation magnetization.

PACS

81.07.-b; 75.75.Fk; 61.46.Df     

Sulfate addition increases methylmercury production in an experimental wetland

Atmospheric mercury is the dominant Hg source to fish in northern Minnesota and elsewhere. However, atmospherically derived Hg must be methylated prior to accumulating in fish. Sulfate-reducing bacteria are thought to be the primary methylators of Hg in the environment. Previous laboratory and field mesocosm studies have demonstrated an increase in methylmercury (MeHg) levels in sediment and peatland porewaters following additions of sulfate. In the current ecosystem-scale study, sulfate was added to half of an experimental wetland at the Marcell Experimental Forest located in northeastern Minnesota, increasing annual sulfate load by approximately four times relative to the control half of the wetland. Sulfate was added on four separate occasions during 2002 and delivered via a sprinkler system constructed on the southeast half (1.0 ha) of the S6 experimental wetland. MeHg levels were monitored in porewater and in outflow from the wetland. Prior to the first sulfate addition, MeHg concentrations (filtered, 0.7 microm) were not statistically different between the control (0.47 +/- 0.10 ng L(-1), n = 12; mean +/- one standard error) and experimental 0.52 +/- 0.05 ng L(-1), n = 18) halves. Following the first addition in May 2002, MeHg porewater concentrations increased to 1.63 +/- 0.27 ng L(-1) two weeks after the addition, a 3-fold increase. Subsequent additions in July and September 2002 did not raise porewater MeHg, but the applied sulfate was not observed in porewaters 24 h after addition. MeHg concentrations in outflow from the wetland also increased leading to an estimated 2.4x increase of MeHg flux from the wetland. Our results demonstrate enhanced methylation and increased MeHg concentrations within the wetland and in outflow from the wetland suggesting that decreasing sulfate deposition rates would lower MeHg export from wetlands.     

Shock-Induced Microstructures in Explosively Fabricated Superconductors

Scanning and transmission electron microscopy (including electron diffraction) have been applied to examine the consolidation, bonding, and characterization of orthorhombic, superconducting YBa₂Cu₃O₇ powder particles in explosive (shock-wave) fabricated aluminum matrix monoliths. The shock wave front (at pressures of approximately 4 GPa) roughly creates an order of magnitude greater density of microtwins and other defects in the orthorhombic structure, which is unaltered by the shock-wave compression. Some evidence for interparticle melting and rapid solidification at large interparticle voids is apparent in small, scattered amorphous regions in the dynamically consolidated superconducting powder regimes. Observations of large d.c. current carrying capacities and current densities estimated to be > 10³ A/cm² in zero applied magnetic field at 77K in practical electrical configurations suggest prospects for very high cirtical current densities resulting from strong flux pinning effects in the YBa₂Cu₃O₇ superconductor at shockwave induced defects.     

Free alpha-subunit and intact TSH secretion in vitro are closely associated in human somatotroph adenomas

B-50(GAP-43) is a phosphoprotein mainly found in the nervous system which plays a major role in neurite growth during development and regeneration as well as in synaptic remodelling. In the mature intact central nervous system, intense B-50 immunoreactivity (B-50-IR) can still be detected in regions which maintain residual capacity for structural re-organization. B-50 expression has been studied extensively in laboratory animals; however, its distribution and regulation in the human spinal cord is largely unknown. As a first step to analyze lesion-induced structural alterations, we investigated the distribution of B-50 protein and mRNA in the normal adult human spinal cord and dorsal root ganglia. Intense B-50-IR was localized to the superficial laminae of the dorsal horn at all segmental levels, the intermediolateral nucleus at thoracic levels and Onuf's nucleus at sacral levels. Scattered neurons, particularly in the ventral horn of lumbar and sacral segmental levels (and occasionally also in Clarke's nucleus) displayed intense B-50-IR in close apposition to the perikaryal and proximal dendritic surfaces. Nonradioactive in situ hybridization indicated that B-50 mRNA could also be detected in neurons of the ventral horn and also in the intermediolateral nucleus. The distribution of B-50 mRNA and protein in the normal human spinal cord shows a marked similarity to that reported in experimental animals, including the selective labelling of Onuf's nucleus. However, the strong B-50-IR on the surface of some large anterior horn motor neurons has not been observed in other mammals. This finding might reflect a particular state of readiness for synaptic plasticity.