Role of analogical reasoning in the induction of problem categories.

In 3 experiments, novices were required to answer questions while reading a series of problems. The questions required them either to analyze individual problem structures (intraproblem processing) or compare problem structures (analogical comparison processing) to derive answers. Ss who engaged in problem comparison processing were found to categorize and describe problems on the basis of problem structure, whereas those who engaged in intraproblem processing, or simply read the problems, categorized and described them on the basis of surface features. Analogical comparisons also facilitated selection and construction of equations relative to intraproblem processing. These results suggest that analogical comparison is an important component in the induction of problem categories. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Characterization of a potent and specific class of antisense oligonucleotide inhibitor of human protein kinase C-alpha expression

The use of antisense oligonucleotides to inhibit the expression of targeted mRNA sequences is becoming increasingly commonplace. Although effective, the most widely used oligonucleotide modification (phosphorothioate) has some limitations. In previous studies we have described a 20-mer phosphorothioate oligodeoxynucleotide inhibitor of human protein kinase C-alpha expression. In an effort to identify improved antisense inhibitors of protein kinase C expression, a series of 2' modifications have been incorporated into the protein kinase C-alpha targeting oligonucleotide, and the effects on oligonucleotide biophysical characteristics and pharmacology evaluated. The incorporation of 2'-O-(2-methoxy)ethyl chemistry resulted in a number of significant improvements in oligonucleotide characteristics. These include an increase in hybridization affinity toward a complementary RNA (1.5 degrees C per modification) and an increase in resistance toward both 3'-exonuclease and intracellular nucleases. These improvements result in a substantial increase in oligonucleotide potency (>20-fold after 72 h). The most active compound identified was used to examine the role played by protein kinase C-alpha in mediating the phorbol ester-induced changes in c-fos, c-jun, and junB expression in A549 lung epithelial cells. Depletion of protein kinase C-alpha protein expression by this oligonucleotide lead to a reduction in c-jun expression but not c-fos or junB. These results demonstrate that 2'-O-(2-methoxy)ethyl-modified antisense oligonucleotides are 1) effective inhibitors of protein kinase C-alpha expression, and 2) represent a class of antisense oligonucleotide which are much more effective inhibitors of gene expression than the widely used phosphorothioate antisense oligodeoxynucleotides.     

Effects of feeding whole cottonseed to lactating dairy cows on glucose and palmitate metabolism

Eight lactating Holstein dairy cows were fed corn silage-based diets with or without whole cottonseed at 18.5% of the dietary dry matter. At 42 days postpartum, a pulse injection of 100 mg glucose/kg body weight was given intravenously and plasma glucose concentration was monitored for 45 min. At 50 d postpartum, biopsies of adipose tissue and mammary tissue were taken and tissue slices were incubated in vitro with either uniform carbon-14 glucose or 1-carbon-14 palmitate. Basal concentration of plasma glucose was not affected by diet, although apparent distribution volume of glucose did seem to decrease due to feeding whole cottonseed. Feeding whole cottonseed decreased uptake of glucose and palmitate in both adipose tissue and mammary tissue and also decreased oxidation of glucose to carbon dioxide in both tissues. Palmitate oxidation was not affected by diet. Incorporation of carbon-14 from glucose into adipose tissue lipids was decreased in cows fed whole cottonseed. Results indicate that fat supplementation in the form of whole cottonseed may decrease palmitate incorporation and glucose utilization for glycerol and reducing equivalent synthesis in both adipose tissue and mammary tissue of lactating dairy cows.     

Probabilistic methodology for assessing changes in the level and molecular weight of barley β-glucan during bread baking

The objective of this study was to create a probabilistic model to assess changes in the levels and molecular weight (Mw) of β-glucan during the bread baking process using Monte Carlo simulation techniques. Three different composite flours were formulated by substituting wheat flour (WF) with barley whole meal flour (BWMF), barley straight grade flour (BSGF) or barley fibre rich fraction (BFRF). The β-glucan level in the flour increased significantly (by approximately 10-fold) when barley was substituted for WF. The baking process resulted in approximately a 47–48% reduction in the β-glucan level in the baked bread (base-line model). The base-line model observed ∼25% and 7% reduction in high molecular weight (HMw) and medium molecular weight (MMw), respectively and a subsequent increase in low molecular weight (LMw). The analysis also showed the importance of various steps involved in bread baking, such as mixing time (Mt), fermentation time (Ft) and baking (BGloss), on the level and Mw of β-glucan in baked breads. A parallel experimental validation study provided confidence in model predictions of β-glucan levels. This study aids in optimising the various unit operations involved in the bread baking process to give a final product with increased nutritional qualities.     

Chemical Ecology of Chemosensation in Asteroidea: Insights Towards Management Strategies of Pest Species

Within the Phylum Echinodermata, the class Asteroidea, commonly known as starfish and sea stars, encompasses a large number of benthos inhabiting genera and species with various feeding modalities including herbivores, carnivores, omnivores and detritivores. The Asteroidea rely on chemosensation throughout their life histories including hunting prey, avoiding or deterring predators, in the formation of spawning aggregations, synchronizing gamete release and targeting appropriate locations for larval settlement. The identities of many of the chemical stimuli that mediate these physiological and behavioural processes remain unresolved even though evidence indicates they play pivotal roles in the functionality of benthic communities. Aspects of chemosensation, as well as putative chemically-mediated behaviours and the molecular mechanisms of chemoreception, within the Asteroidea are reviewed here, with particular reference to the coral reef pest the Crown-of-Thorns starfish Acanthaster planci species complex, in the context of mitigation of population outbreaks.     

Signal-to-noise ratios of array receiving systems with internal losses

A formulation of the signal-to-noise ratio (SNR) for a typical antenna array receiving system that is more complete than those now available in the literature is presented. In addition to the external noise accepted by the array, it includes all forms of internal noise generated by the lossy components of the system. Distinct measurable factors account for distinct noise sources. For the analysis, it is shown that the actual lossy system can be replaced by an equivalent lossless system with appropriate attenuators. The formulation is used to design the combining network that will optimize the receiving system SNR for signals incident from a given direction in the presence of a known external noise distribution. The theory is applied to a specific array antenna receiving system operating under a variety of noise conditions, internal as well as external. A discussion of some typical results is presented.     

Combinatorial Materials and Catalyst Research

The advent of combinatorial chemistry promises to profoundly change the way research is carried out across a wide spectrum of science. For example, the Figure shows a titanium complex that has 10 000 000 possible molecular variations based on a diversity of only 10 choices for each R group. A combinatorial approach to this challenge would allow many more of these compounds to be examined than could be achieved in a linear fashion.     

A farm‐to‐fork model to evaluate the level of polyacetylenes in processed carrots

Naturally occurring aliphatic C₁₇ polyacetylene compounds [falcarinol (FaOH), falcarindiol (FaDOH) and falcarindiol‐3‐acetate (FaDOAc)] in carrots are known for their bioactivity and health benefits. This study assesses the impact of pre‐ and postharvest processes (including food processing stages) on the level of polyacetylenes and evaluates subsequent human exposure using Monte Carlo simulation techniques. The model includes data inputs from both experimental and published literature sources. The sensitivity analysis highlights the importance of cultivar selection and agronomic factors. The sensitivity analysis also showed that peeling, blanching and boiling time of carrots have a significant negative influence on the level of polyacetylenes with correlation coefficients of ?0.15, ?0.14 and ?0.19 for FaOH, ?0.47, ?0.23 and ?0.20 for FaDOH and ?0.29, ?0.26 and ?0.25 for FaDOAc, respectively. The scenario analysis shows the practical application of the proposed model for industrial processing of carrots. This model could facilitate food processors in optimising critical processing factors such as peeling and cutting prior to processing of carrots.     

Responses of dairy cows to supplemental rumen-protected forms of methionine and lysine.

Multiparous Holstein cows at six universities were utilized to examine effects of ruminally protected methionine and lysine on lactational performance. Three hundred and four cows began the study; 259 cows were included in the production analysis. Following a 21-d standardization period, cows received a basal diet of corn silage and ground corn supplemented with one of five dietary treatments, which were supplements of soybean meal or corn gluten meal, the latter with zero and three combinations of protected methionine and lysine (methionine; methionine and lysine; methionine and double (2x) lysine). Treatment effects were evaluated during early, mid, late, and total lactation (22 to 112, 113 to 224, 225 to 280, and 22 to 280 d postpartum, respectively). On a DM basis, ratios of forage to concentrate (50:50, 60:40, and 70:30) increased, and dietary CP (16.0, 14.5, and 13.0%) decreased during the three periods of lactation. Amount of amino acid supplementation also decreased (15, 12, and 9 g/d methionine; 20, 16, and 12 g/d lysine; and 40, 32, and 24 g/d 2x lysine) with period of lactation. Actual and least squares means for milk, FCM, and milk protein yields were greater for soybean than for corn gluten meal during early, mid, and total lactation. In addition, these variables responded linearly to lysine in early lactation. Response to lysine was quadratic during mid and total lactation for these variables. Differences in nutrient intake explained production responses to protein sources but not to lysine. Serum amino acid responses primarily reflected differences in dietary protein source and rumen-protected amino acid.