2,410 research outputs found
Spectral line shape modeling and ion temperature fluctuations in tokamak edge plasmas
In this work, we use a passive advection model for ion temperature
fluctuations, in order to investigate their effects on Doppler Spectral line
shapes. The relevance of the model is discussed in the framework of the
Braginskii equations, and the subsequent Probability Density Function
evaluation relies on results obtained in neutral fluids. The resulting Doppler
line profiles are shown to exhibit characteristic exponential tails.Comment: 6 pages, 2 figures, to be published in Contributions to Plasma
Physic
With development, list recall includes more chunks, not just larger ones.
The nature of the childhood development of immediate recall has been difficult to determine. There could be a developmental increase in either the number of chunks held in working memory or the use of grouping to make the most of a constant capacity. In 3 experiments with children in the early elementary school years and adults, we show that improvements in the immediate recall of word and picture lists come partly from increases in the number of chunks of items retained in memory. This finding was based on a distinction between access to a studied group of items (i.e., recall of at least 1 item from the group) and completion of the accessed group (i.e., the proportion of the items recalled from the group). Access rates increased with age, even with statistical controls for completion rates, implicating development of capacity in chunks. (PsycINFO Database Record (c) 2010 APA, all rights reserved
Taking Informed Action in Challenging Times: Helping Community Foundations during Economic Downturn
Following up on CF Insights' November 2008 report "Making Informed Decisions in Uncertain Times", this report is aimed at helping community foundations take informed action in relation to their operating models and community activities in reaction to the economic slump. The findings are based on quantitative and qualitative research conducted with 95 community foundations during the spring of 2009. The research findings overall underscore that the field has been able to "make lemonade" from the crisis. In light of tepid expectations for assets and gifts for the rest of 2009, community foundations are being creative and thoughtful in how they allocate precious resources andstep up their community leadership.
Maximum Recommended Dosage of Lithium for Pregnant Women Based on a PBPK Model for Lithium Absorption
Treatment of bipolar disorder with lithium therapy during pregnancy is a medical challenge. Bipolar disorder is more prevalent in women and its onset is often concurrent with peak reproductive age. Treatment typically involves administration of the element lithium, which has been classified as a class D drug (legal to use during pregnancy, but may cause birth defects) and is one of only thirty known teratogenic drugs. There is no clear recommendation in the literature on the maximum acceptable dosage regimen for pregnant, bipolar women. We recommend a maximum dosage regimen based on a physiologically based pharmacokinetic (PBPK) model. The model simulates the concentration of lithium in the organs and tissues of a pregnant woman and her fetus. First, we modeled time-dependent lithium concentration profiles resulting from lithium therapy known to have caused birth defects. Next, we identified maximum and average fetal lithium concentrations during treatment. Then, we developed a lithium therapy regimen to maximize the concentration of lithium in the mother's brain, while maintaining the fetal concentration low enough to reduce the risk of birth defects. This maximum dosage regimen suggested by the model was 400 mg lithium three times per day
The stable marriage problem with master preference lists
We study variants of the classical stable marriage problem in which the preferences of the men or the women, or both, are derived from a master preference list. This models real-world matching problems in which participants are ranked according to some objective criteria. The master list(s) may be strictly ordered, or may include ties, and the lists of individuals may involve ties and may include all, or just some, of the members of the opposite sex. In fact, ties are almost inevitable in the master list if the ranking is done on the basis of a scoring scheme with a relatively small range of distinct values. We show that many of the interesting variants of stable marriage that are NP-hard remain so under very severe restrictions involving the presence of master lists, but a number of special cases can be solved in polynomial time. Under this master list model, versions of the stable marriage problem that are already solvable in polynomial time typically yield to faster and/or simpler algorithms, giving rise to simple new structural characterisations of the solutions in these cases
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