Universal Multifractality in Quantum Hall Systems with Long-Range Disorder Potential

We investigate numerically the localization-delocalization transition in quantum Hall systems with long-range disorder potential with respect to multifractal properties. Wavefunctions at the transition energy are obtained within the framework of the generalized Chalker--Coddington network model. We determine the critical exponent $\alpha_0$ characterizing the scaling behavior of the local order parameter for systems with potential correlation length $d$ up to $12$ magnetic lengths $l$. Our results show that $\alpha_0$ does not depend on the ratio $d/l$. With increasing $d/l$, effects due to classical percolation only cause an increase of the microscopic length scale, whereas the critical behavior on larger scales remains unchanged. This proves that systems with long-range disorder belong to the same universality class as those with short-range disorder.Comment: 4 pages, 2 figures, postsript, uuencoded, gz-compresse

Self-Regulation in a Web-Based Course: A Case Study

Little is known about how successful students in Web-based courses self-regulate their learning. This descriptive case study used a social cognitive model of self-regulated learning (SRL) to investigate how six graduate students used and adapted traditional SRL strategies to complete tasks and cope with challenges in a Web-based technology course; it also explored motivational and environmental influences on strategy use. Primary data sources were three transcribed interviews with each of the students over the course of the semester, a transcribed interview with the course instructor, and the students’ reflective journals. Archived course documents, including transcripts of threaded discussions and student Web pages, were secondary data sources. Content analysis of the data indicated that these students used many traditional SRL strategies, but they also adapted planning, organization, environmental structuring, help seeking, monitoring, record keeping, and self-reflection strategies in ways that were unique to the Web-based learning environment. The data also suggested that important motivational influences on SRL strategy use—self-efficacy, goal orientation, interest, and attributions—were shaped largely by student successes in managing the technical and social environment of the course. Important environmental influences on SRL strategy use included instructor support, peer support, and course design. Implications for online course instructors and designers, and suggestions for future research are offered

Teacher-Made Tests in History

Article published in Teaching History by Alder, DeBloois, and Eastmond, Jr

A future without forgiveness: beyond reconciliation in transitional justice

This article questions the promotion of reconciliation in transitional justice contexts. The article puts forward a critique of reconciliation in practice and questions mainstream definitions of reconciliation. The principle that these forms of reconciliation are desirable is also questioned. It is argued that examples of genuine reconciliation are difficult to find, that the promotion of reconciliation is frequently emphasised at the expense of substantive societal change, that emphasis on reconciliation (narrowly defined) risks taking agency away from those affected by conflict and that emphasis on reconciliation may obscure injustice and may promote acceptance of the status quo. The article suggests that reconciliation is not a necessary condition of, and should be de-emphasised in, transitional justice and, if it is promoted at all, that a different, less prescriptive notion of reconciliation is necessary

Peroxidase-dependent metabolism of benzene's phenolic metabolites and its potential role in benzene toxicity and carcinogenicity.

The metabolism of two of benzene's phenolic metabolites, phenol and hydroquinone, by peroxidase enzymes has been studied in detail. Studies employing horseradish peroxidase and human myeloperoxidase have shown that in the presence of hydrogen peroxide phenol is converted to 4,4'-diphenoquinone and other covalent binding metabolites, whereas hydroquinone is converted solely to 1,4-benzoquinone. Surprisingly, phenol stimulates the latter conversion rather than inhibiting it, an effect that may play a role in the in vivo myelotoxicity of benzene. Indeed, repeated coadministration of phenol and hydroquinone to B6C3F1 mice results in a dramatic and significant decrease in bone marrow cellularity similar to that observed following benzene exposure. A mechanism of benzene-induced myelotoxicity is therefore proposed in which the accumulation and interaction of phenol and hydroquinone in the bone marrow and the peroxidase-dependent formation of 1,4-benzoquinone are important components. This mechanism may also be responsible, at least in part, for benzene's genotoxic effects, as 1,4-benzoquinone has been shown to damage DNA and is shown here to induce multiple micronuclei in human lymphocytes. Secondary activation of benzene's phenol metabolites in the bone marrow may therefore play an important role in benzene's myelotoxic and carcinogenic effects

Health risk assessment of instant noodles commonly consumed in Port Harcourt, Nigeria

The current study investigated the levels of some heavy metals [Lead (Pb), Arsenic (As), Nickel (Ni), Mercury (Hg), Copper (Cu), Cadmium (Cd), Aluminium (Al) and Chromium (Cr)] and Polycyclic Aromatic Hydrocarbons (PAHs) in six brands of instant noodles (CFN, GFC, NGP, GAA, CUN and FCS) commonly consumed in Port Harcourt, Nigeria. Risks of consumption of contaminated noodles were also assessed. Heavy metals content and PAHs were determined using Flame Atomic Absorption Spectrophotometer (AAS) and Gas Chromatography (GC), respectively. Concentration of heavy metals as Pb, Ni, Cu, Al and Cr were detected while As, Hg and Cd were not detected in noodles. High average concentration (mean ± SD mg/kg) of Pb were observed in brands CFN (3.163 ± 0.21) and GFC (1.022 ± 0.08) which were significantly higher (P≤0.05) than in NGP (0.043 ± 0.15) and GAA (0.276 ± 0.18), although all were above WHO permissible limits (0.025 mg/kg). Target Hazard Quotient and Hazard Index for Pb were >1 in brands CFN and GFC indicating unacceptable risk. Results of PAHs showed brands had total PAHs (mg/kg) in the order: CFN >CUN >GAA >NGP >FCS > GFC. Although Carcinogenic Risks associated with these noodles are within permissible range, consumption of CFN and GFC could pose greater health risk to consumers. Long term consumption of brands CUN, CFN and GAA may have higher probability of carcinogenesis among consumers. We therefore recommend more diligent regulatory policies and monitoring by relevant Government agencies (WHO, NAFDAC, CPC and SON) to ensure wholesome noodles get to consumers

Laboratory phenomics predicts field performance and identifies superior indica haplotypes for early seedling vigour in dry direct-seeded rice

Seedling vigour is an important agronomic trait and is gaining attention in Asian rice (Oryza sativa) as cultivation practices shift from transplanting to forms of direct seeding. To understand the genetic control of rice seedling vigour in dry direct seeded (aerobic) conditions we measured multiple seedling traits in 684 accessions from the 3000 Rice Genomes (3K-RG) population in both the laboratory and field at three planting depths. Our data show that phenotyping of mesocotyl length in laboratory conditions is a good predictor of field performance. By performing a genome wide association study, we found that the main QTL for mesocotyl length, percentage seedling emergence and shoot biomass are co-located on the short arm of chromosome 7. We show that haplotypes in the indica subgroup from this region can be used to predict the seedling vigour of 3K-RG accessions. The selected accessions may serve as potential donors in genomics-assisted breeding programs

Down‐regulation of key genes involved in carbon metabolism in Medicago truncatula results in increased lipid accumulation in vegetative tissue

Alfalfa (Medicago sativa L.), is the most widely grown perennial forage crop, which is a close relative of the model diploid legume Medicago truncatula. However, use of alfalfa lead to substantial greenhouse gas emissions and economic losses related to inefficiencies in rumen fermentation. The provision of supplemental lipids has been used as a strategy to mitigate these issues, but it is a costly approach. The ability to enhance lipid content within the vegetative tissues of alfalfa would therefore be very advantageous. As such, our aim was to assess and select gene candidates to increase total shoot lipid content in M. truncatula using a virus‐induced gene silencing (VIGS) approach. We targeted gene homologs of the SUGAR‐DEPENDANT 1 (SDP1), ADP‐GLUCOSE‐PYROPHOSPHORYLASE SMALL SUBUNIT 1 (APS1), TRIGALACTOSYLDIACYLGLYCEROL 5 (TGD5) and PEROXISOMAL ABC TRANSPORTER 1 (PXA1) in M. truncatula for silencing. Reduced target transcript levels were confirmed and changes of shoot lipid content and fatty acid composition were measured. Silencing of SDP1, APS1 and PXA1 each resulted in significant increases in shoot total lipid content. Significantly increased proportions of α‐linolenic acid (18:3Δ9cis,12cis,15cis) were observed and stearic acid (18:0) levels significantly decreased in the total acyl lipids extracted from vegetative tissues of each of the M. truncatula silenced plants. In contrast, palmitic acid (16:0) levels were significantly decreased in only SDP1 and PXA1‐silenced plants. Genes of PXA1 and SDP1 would be ideal targets for mutation as a means of improving the quality of alfalfa for increasing feed efficiency and minimizing greenhouse gas emissions from livestock production in the future