Transfer of fluency across repetitions and across texts.

Three experiments examined transfer of reading fluency across repeated readings of the same text and across related but different texts with a total of 102 college students. In Exp 1, it was found that a paraphrase that altered the syntactic structure of sentences but not the lexical identity of main concepts or the unfolding of the message was reprocessed as an unchanged repetition. However, when the paraphrase altered the lexical identity of main concepts, there was a loss in the repetition benefit. In Exps 2 and 3, there was transfer from a representation of 1 text to the reading of a 2nd text only if the messages were continuous. Results are discussed in terms of the influence of episodic text representations on reading fluency. (French abstract) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Impedance model of electrolyte-insulator-semiconductor structure with porous silicon semiconductor

We present a generic impedance model for the porous silicon|electrolyte structure that is valid for a range of interfacial layers and bias in these structures. The model is validated using three widely different porous structures: short irregular silicon columns and pores, long cylindrical silicon columns and pores; and branched interconnected silicon microchannels and voids in a mesh structure. The model incorporates appropriate RC or constant phase elements for the different parts of the porous structure, namely, the top of the silicon columns (channels)|electrolyte, the column (channel) walls|electrolyte in the pores/channels, and the electrolyte|semiconductor interface at the base of the pores/channels. This physical model underscores the effects of column/channel depletion and accumulation, either due to applied bias or change of surface charge, to the impedance spectra of the device. The model helps to explain why the porosity needs to be optimized for specific applications and helps as a measurement tool for optimization.     

Organic aerosol spatial/temporal patterns: perspectives of measurements and model

Ambient measurements from SEARCH and model results from CMAQ-MADRID are analyzed side by side for the southeastern United States to understand the strengths and weaknesses of an air quality model in reproducing key spatial and temporal patterns related to organic aerosol (OA), with inferences regarding secondary organic aerosol (SOA). The model predicts a larger difference in OA concentrations between an urban (JST) and a rural site (YRK) than indicated by measurements. Modeled OA concentrations at JST and YRK are more strongly correlated than measurements. On average, models may understate urban OA emissions, while overstating urban SOA production; measurements indicate that SOA production takes place on the regional scale. Modeled diurnal fluctuations for OA are stronger than measured, due partially to overestimations of the temperature dependence parameters (deltaH(vap)) for SOA in the model. Urban-rural differences in the composition of SOA, inferred from the variations of estimated deltaH(vap), are not properly captured by the model, which does not represent multiple generations of SOA or varied reaction pathways as a function of chemical regimes. Model results are hampered by day-of-the-week and diurnal allocation issues related to EC and OA emissions. Top quintile (20%) afternoon OA concentrations are observed in both warm and cold seasons at the urban site. The frequency of high OA in the cold season is overstated in the model. The model predicts the warm vs cold season frequency of elevated OA episodes better at YRK than at JST, suggesting that regional emissions, chemistry, and transport are better simulated than urban processes.     

Effect of Erythropoietin on the Expression of Murine Transferrin Receptor 2

Erythropoietin (EPO) downregulates hepcidin expression to increase the availability of iron; the downregulation of hepcidin is mediated by erythroferrone (ERFE) secreted by erythroblasts. Erythroblasts also express transferrin receptor 2 (TFR2); however, the possible role of TFR2 in hepcidin downregulation is unclear. The purpose of the study was to correlate liver expression of hepcidin with the expression of ERFE and TFR2 in murine bone marrow and spleen at 4, 16, 24, 48, 72 and 96 h following administration of a single dose of EPO. Splenic Fam132b expression increased 4 h after EPO injection; liver hepcidin mRNA was decreased at 16 h. In the spleen, expression of TFR2 and transferrin receptor (TFR1) proteins increased by an order of magnitude at 48 and 72 h after EPO treatment. The EPO-induced increase in splenic TFR2 and TFR1 was associated with an increase in the number of Tfr2- and Tfr1-expressing erythroblasts. Plasma exosomes prepared from EPO-treated mice displayed increased amount of TFR1 protein; however, no exosomal TFR2 was detected. Overall, the results confirm the importance of ERFE in stress erythropoiesis, support the role of TFR2 in erythroid cell development, and highlight possible differences in the removal of TFR2 and TFR1 from erythroid cell membranes.     

Photoelectrochemical properties of porous silicon based novel photoelectrodes

Porous silicon interfaces have been modified with nitrided TiO₂ (TiON) nanoparticles to develop highly efficient photoelectrodes. Photoelectrodes were prepared by impregnating the electrochemically prepared porous silicon microchannels with titanium oxynitride. Photocatalytic measurements were carried out on titanium oxynitride particles in water‐methanol mixture and the results showed a dependence on the nitrogen concentration. Among the photoelectrodes used for photocurrent measurements, porous silicon impregnated with TiO₂ nitrided at 600 °C showed maximum photocurrent increase after exposure to sunlight‐type radiation. The enhancement in photocurrent was one order more for the porous silicon/titanium oxynitride hetero‐structure than that of polished silicon/titanium oxynitride hetero‐structure. Photoelectrodes thus prepared were found to have stable performance for a period of six months. This observation promises the possibility of using porous silicon/titanium oxynitride hetero‐structures as efficient electrodes for photovoltaic cells. Copyright © 2010 John Wiley & Sons, Ltd.     

Butyrate and Propionate Restore the Cytokine and House Dust Mite Compromised Barrier Function of Human Bronchial Airway Epithelial Cells

Barrier dysfunction of airway epithelium contributes to the development of allergies, airway hyper-responsiveness and immunological respiratory diseases. Short-chain fatty acids (SCFA) enhance and restore the barrier function of the intestinal epithelium. This study investigated whether acetate, propionate and butyrate enhance the integrity of bronchial epithelial cells. Differentiating human bronchial epithelial cells (16HBE) grown on transwells were exposed to butyrate, propionate and acetate while trans-epithelial electrical resistance was monitored over time. Restorative effects of SCFA were investigated by subsequent incubation of cells with IL-4, IL-13 or house dust mite extract and SCFA. SCFA effects on IL-4-induced cytokine production and the expression of zonula occludens-1 (ZO-1) and Mitogen-activated protein kinases (MAPK) signalling pathways were investigated by ELISA and Western blot assays. Propionate and butyrate enhanced the barrier function of differentiating 16HBE cells and induced complete recovery of the barrier function after exposure to the above-mentioned stimuli. Butyrate decreased IL-4-induced IL-6 production. IL-4 decreased ZO-1 protein expression and induced phosphorylation of extracellular signal-regulated protein kinases 1/2 (ERK1/2) and c-Jun N-terminal kinases (JNK) in 16HBE cells, both of which could be restored by SCFA. SCFA showed prophylactic and restorative effects on airway epithelial barrier function, which might be induced by increased ZO-1 expression.     

The uncertainty interaction problem in self-adaptive systems

Software and Systems Modeling - The problem of mitigating uncertainty in self-adaptation has driven much of the research proposed in the area of software engineering for self-adaptive systems in...     

Relationship among turbidity, particle counts and bacteriological quality within water distribution lines

The turbidity standard for water quality was evaluated in relation to total particle counts, heterotrophic plate counts and epifluorescence direct cell counts of three different municipal drinking-waters. Turbidity and particle counts were directly proportional. There was no predictable relationship between bacteriological quality and turbidity or particle counts. Heterotrophic plate counts under-estimated epifluorescence direct cell counts by a factor of at least 500. Water quality degradation occurred in municipal drinking-water systems because of intermittent short duration events that resulted in high turbidity, particle counts and heterotrophic plate counts. Further, for all parameters measured variability increased with distance traveled within a pipe except for ground water.     

Farmers,fires, and forests: a green alternative to shifting cultivation for conservation of the Maya forest?

When fires blazed through Mexico's forests in 1998, the country experienced a new sense of urgency in its attempts to combat ecosystem degradation and loss of biodiversity. Secretaría de Medio Ambiente y Recursos Naturales (SEMARNAT, the federal environmental protection agency) identified the use of fire in agriculture as a major contributor to the conflagration. Traditional “slash-and-burn” systems are still widely practiced in the southeast of Mexico, and finding a substitute for burning, especially in and near protected areas, became imperative (SEMARNAT, 2001). Experience from different parts of Central America indicated that green manure/cover crop systems (g/cc) could increase soil fertility, reduce erosion, control weeds and raise the yield of maize; the hope was that this system could replace slash-and-burn practices with their attendant risk of forest fires. We present the case study of a project introducing a green cover crop to traditional, resource-poor, maize farmers in one community of the Yucatan peninsula and preliminary results from a similar project in the Calakmul Biosphere Reserve, discussing the data in the light of the on-going debates concerning both fire policy and soil erosion. We conclude that, in spite of demonstrating some advantages, adoption in the peninsula has been hindered by environmental, economic and socio-cultural factors. Mexican efforts to eliminate fire from the forests must also be assessed with reference to the scientific literature by fire experts and historical ecologists, indicating that prohibition of small fires may actually decrease total biodiversity, while increasing the probabilities of catastrophic forest fires.     

Biodegradable quantum dot nanocomposites enable live cell labeling and imaging of cytoplasmic targets

Semiconductor quantum dots (QDs) offer great promise as the new generation of fluorescent probes to image and study biological processes. Despite their superior optical properties, QDs for live cell monitoring and tracking of cytoplasmic processes remain limited due to inefficient delivery methods available, altered state or function of cells during the delivery process and the requirement of surface-functionalized QDs for specific labeling of subcellular structures. Here, we present a noninvasive method to image subcellular structures in live cells using bioconjugated QD nanocomposites. By incorporating antibody-coated QDs within biodegradable polymeric nanospheres, we have designed a bioresponsive delivery system that undergoes endolysosomal to cytosolic translocation via pH-dependent reversal of nanocomposite surface charge polarity. Upon entering the cytosol, the polymer nanospheres undergo hydrolysis thus releasing the QD bioconjugates. This approach facilitates multiplexed labeling of subcellular structures inside live cells without the requirement of cell fixation or membrane permeabilization. As compared to conventional intracellular delivery techniques, this approach allows the high throughput cytoplasmic delivery of QDs with minimal toxicity to the cell. More importantly, this development demonstrates an important rational strategy for the design of a multifunctional nanosystem for biological applications.