Routine characterization and interpretation of complex alkali feldspar intergrowths

Almost all alkali feldspar crystals contain a rich inventory of exsolution, twin, and domain microtextures that form subsequent to crystal growth and provide a record of the thermal history of the crystal and often of its involvement in replacement reactions, sometimes multiple. Microtextures strongly influence the subsequent behavior of feldspars at low temperatures during diagenesis and weathering. They are central to the retention or exchange of trace elements and of radiogenic and stable isotopes. This review is aimed at petrologists and geochemists who wish to use alkali feldspar microtextures to solve geological problems or who need to understand how microtextures influence a particular process. We suggest a systematic approach that employs methods available in most well founded laboratories. The crystallographic relationships of complex feldspar intergrowths were established by the 1970s, mainly using single-crystal X-ray diffraction, but such methods give limited information on the spatial relationships of the different elements of the microtexture, or of the mode and chronology of their formation, which require the use of microscopy. We suggest a combination of techniques with a range of spatial resolution and strongly recommend the use of orientated sections. Sections cut parallel to the perfect (001) and (010) cleavages are the easiest to locate and most informative. Techniques described are light microscopy; scanning electron microscopy using both backscattered and secondary electrons, including the use of surfaces etched in the laboratory; electron-probe microanalysis and analysis by energy-dispersive spectrometry in a scanning electron microscope; transmission electron microscopy. We discuss the use of cathodoluminescence as an auxiliary technique, but do not recommend electron-backscattered diffraction for feldspar work. We review recent publications that provide examples of the need for great care and attention to pre-existing work in microtextural studies, and suggest several topics for future work

Effects of Information about Invasive Species on Risk Perception and Seafood Demand by Gender and Race

In this paper we consider the effects of negative and positive risk information on perceived seafood risks and seafood consumption by gender and race. The data is from a Mid-Atlantic survey of coastal seafood consumers. We elicit risk perceptions in three risk scenarios with a dichotomous choice with a follow-up question format. We elicit continuous revealed and stated preference seafood consumption in nine risk and price scenarios. Analysis in four gender and race categories indicates that demographic groups respond to the positive and negative information in different ways. Communication of risk information as risk mitigation policy is a challenge. Key Words:

The Welfare Effects of Pfiesteria-Related Fish Kills: A Contingent Behavior Analysis of Seafood Consumers

We use contingent behavior analysis to study the effects of pfiesteria-related fish kills on the demand for seafood in the Mid-Atlantic region. We estimate a set of demand difference models based on individual responses to questions about seafood consumption in the presence of fish kills and with different amounts of information provided about health risks. We use a random-effects Tobit model to control for correlation across each observation and to account for censoring. We find that (i) pfiesteria-related fish kills have a significant negative effect on the demand for seafood even though the fish kills pose no known threat to consumers through sea-food consumption, (ii) seafood consumers are not responsive to expert risk information designed to reassure them that seafood is safe in the presence of a fish kill, and (iii) a mandatory seafood inspection program largely eliminates the welfare loss incurred due to misinformation.pfiesteria, seafood demand, non-market valuation, Resource /Energy Economics and Policy,

The Welfare Effects of Pfiesteria-Related Fish Kills in Seafood Markets: A Contingent Behavior Analysis

We use contingent behavior analysis to study the effects of Pfiesteria related fish kills on the demand for seafood in the Mid-Atlantic region. We use a phone-mail-phone survey to look at the effects of various information provision mechanisms used to ameliorate the effects of misinformation regarding fish kills. A set of demand difference models are estimated based on individual responses to multiple questions about seafood consumption with and without fish kills present and with various health risk information treatments. Random effects Tobit models are used to control for the panel nature of responses and natural censoring of the stated responses. We find that 1) Pfiesteria related fish kills have a significant negative effect on the demand for seafood, 2) seafood consumers are nonresponsive to expert risk information designed to reassure consumers that seafood is safe in the presence of a fish kill, and 3) a mandatory seafood inspection program completely eliminates avoidance costs incurred due to misinformation. We estimate that the aggregate avoidance costs incurred in the month immediately following a Pfiesteria related fish kill is $50-$130 million.

Cost and U.S. public policy for new coal power plants with carbon capture and sequestration

This paper provides a financial analysis for new supercritical pulverized coal plants with carbon capture and sequestration (CCS) that compares the effects of two relevant climate policies. First, an updated cost estimate is presented for new supercritical pulverized coal plants, both with and without CCS. The capital cost escalation of recent years can be attributed to rising materials, plant supply, and plant contractor constraints. This estimate is then compared with recent estimates from public sources. Second, several current and proposed public policies relevant to CCS are presented. Finally, a financial analysis is performed to evaluate the effectiveness of two likely US carbon regulations on deploying Nth-plant CCS technology. The major conclusion is that the leading US carbon cap-and-trade bills will likely not be sufficient to deploy CCS technology in a manner consistent with a 550 ppm CO[subscript 2] stabilization scenario. A more aggressive carbon policy including CCS research, development, and demonstration must be considered to achieve this goal with significant CCS deployment.Massachusetts Institute of Technology. Carbon Sequestration InitiativeMIT Industrial Performance Cente

Phosphorylation of the actin binding protein Drebrin at S647 and is regulated by neuronal activity and PTEN

Defects in actin dynamics affect activity-dependent modulation of synaptic transmission and neuronal plasticity, and can cause cognitive impairment. A salient candidate actin-binding protein linking synaptic dysfunction to cognitive deficits is Drebrin (DBN). However, the specific mode of how DBN is regulated at the central synapse is largely unknown. In this study we identify and characterize the interaction of the PTEN tumor suppressor with DBN. Our results demonstrate that PTEN binds DBN and that this interaction results in the dephosphorylation of a site present in the DBN C-terminus - serine 647. PTEN and pS647-DBN segregate into distinct and complimentary compartments in neurons, supporting the idea that PTEN negatively regulates DBN phosphorylation at this site. We further demonstrate that neuronal activity increases phosphorylation of DBN at S647 in hippocampal neurons in vitro and in ex vivo hippocampus slices exhibiting seizure activity, potentially by inducing rapid dissociation of the PTEN:DBN complex. Our results identify a novel mechanism by which PTEN is required to maintain DBN phosphorylation at dynamic range and signifies an unusual regulation of an actin-binding protein linked to cognitive decline and degenerative conditions at the CNS synapse

Systematic survey of variants in TBX1 in non-syndromic tetralogy of Fallot identifies a novel 57 base pair deletion that reduces transcriptional activity but finds no evidence for association with common variants

Background Tetralogy of Fallot (TOF) is common in individuals with hemizygous deletions of chromosome 22q11.2 that remove the cardiac transcription factor TBX1.Objective To assess the contribution of common and rare TBX1 genetic variants to TOF.Design Rare TBX1 variants were sought by resequencing coding exons and splice-site boundaries. Common TBX1 variants were investigated by genotyping 20 haplotype-tagging SNPs capturing all the common variations present at the locus. Association analysis was performed using the program UNPHASED.Patients TBX1 exons were sequenced in 93 patients with non-syndromic TOF. Single nucleotide polymorphism analysis was performed in 356 patients with TOF, their parents and healthy controls.Results Three novel variants not present in 1000 chromosomes from healthy ethnically matched controls were identified. One of these variants, an in-frame 57 base-pair deletion in the third exon which removed 19 evolutionarily conserved residues, decreased transcriptional activity by 40% in a dual luciferase assay (p=0.008). Protein expression studies demonstrated that this mutation affected TBX1 protein stability. After correction for multiple comparisons, no significant associations between common genetic variants and TOF susceptibility were found.Conclusion This study demonstrates that rare TBX1 variants with functional consequences are present in a small proportion of non-syndromic TOF

Status of the QCDSP project

We describe the completed 8,192-node, 0.4Tflops machine at Columbia as well as the 12,288-node, 0.6Tflops machine assembled at the RIKEN Brookhaven Research Center. Present performance as well as our experience in commissioning these large machines is presented. We outline our on-going physics program and explain how the configuration of the machine is varied to support a wide range of lattice QCD problems, requiring a variety of machine sizes. Finally a brief discussion is given of future prospects for large-scale lattice QCD machines.Comment: LATTICE98(machines), 3 pages, 1 picture, 1 figur