11,879 research outputs found

    Femtosecond pulses and dynamics of molecular photoexcitation: RbCs example

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    We investigate the dynamics of molecular photoexcitation by unchirped femtosecond laser pulses using RbCs as a model system. This study is motivated by a goal of optimizing a two-color scheme of transferring vibrationally-excited ultracold molecules to their absolute ground state. In this scheme the molecules are initially produced by photoassociation or magnetoassociation in bound vibrational levels close to the first dissociation threshold. We analyze here the first step of the two-color path as a function of pulse intensity from the low-field to the high-field regime. We use two different approaches, a global one, the 'Wavepacket' method, and a restricted one, the 'Level by Level' method where the number of vibrational levels is limited to a small subset. The comparison between the results of the two approaches allows one to gain qualitative insights into the complex dynamics of the high-field regime. In particular, we emphasize the non-trivial and important role of far-from-resonance levels which are adiabatically excited through 'vertical' transitions with a large Franck-Condon factor. We also point out spectacular excitation blockade due to the presence of a quasi-degenerate level in the lower electronic state. We conclude that selective transfer with femtosecond pulses is possible in the low-field regime only. Finally, we extend our single-pulse analysis and examine population transfer induced by coherent trains of low-intensity femtosecond pulses.Comment: 25 pages, 12 figure

    ANALYSIS OF BORROWER AND LENDER USE OF INTEREST ASSISTANCE ON FSA GUARANTEED FARM LOANS

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    The Farm Security and Rural Investment Act of 2002 made permanent the interest assistance program for the Farm Service Agency's guaranteed loans, authorized a significant increase in funding for the program, and targeted funding for beginning farmers and ranchers. The research presented here provides a basic descriptive analysis of past use. In particular, borrower data for Federal fiscal years 1985 through 2002 are examined in several dimensions. These dimensions include geographic, borrower type, lender type, interest rate differentials, percent guarantee, and the status of the loan as to whether a loss claim was paid or the loan remained active. Even though the program has been in existence for more than 15 years, little is known about its impact and utilization. This research is an initial step in documenting usage of the program.Agricultural and Food Policy, Agricultural Finance,

    Evidence for RNA transport in rat optic nerve

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    Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/66066/1/j.1471-4159.1969.tb08995.x.pd

    On Estimation of Fully Entangled Fraction

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    We study the fully entangled fraction (FEF) of arbitrary mixed states. New upper bounds of FEF are derived. These upper bounds make complements on the estimation of the value of FEF. For weakly mixed quantum states, an upper bound is shown to be very tight to the exact value of FEF.Comment: 8 pages, 2 figure

    Variation in grouping patterns, mating systems and social structure: what socio-ecological models attempt to explain

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    Socio-ecological models aim to predict the variation in social systems based on a limited number of ecological parameters. Since the 1960s, the original model has taken two paths: one relating to grouping patterns and mating systems and one relating to grouping patterns and female social structure. Here, we review the basic ideas specifically with regard to non-human primates, present new results and point to open questions. While most primates live in permanent groups and exhibit female defence polygyny, recent studies indicate more flexibility with cooperative male resource defence occurring repeatedly in all radiations. In contrast to other animals, the potential link between ecology and these mating systems remains, however, largely unexplored. The model of the ecology of female social structure has often been deemed successful, but has recently been criticized. We show that the predicted association of agonistic rates and despotism (directional consistency of relationships) was not supported in a comparative test. The overall variation in despotism is probably due to phylogenetic grade shifts. At the same time, it varies within clades more or less in the direction predicted by the model. This suggests that the model's utility may lie in predicting social variation within but not across clades

    Antimalarial use and the associated factors in rural nigeria following implementation of affordable medicines facility-malaria (amfm) price subsidy

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    Purpose: This study was set out to find out the pattern of antimalarial drug use in a Nigerian rural community following the aggressive price subsidy of Artemisinin Combination Therapy(ACT) recently embarked upon by Roll Back Malaria partners through Affordable Medicines Facility-malaria (AMFm).Methods: Questioners were administered to 310 adult members of the community with the most recent malaria episodes so as to find out about the drugs used and some of the factors associated with the choice of the drug.Result: Although the overall use of ACT (13.55%) in this community was about 4 times higher than what it used to be, Chloroquine 123(39.62%) and sulphadozine/pyrimathamine 120(38.71%) were the mostly used antimalarial agents. Choice of drug used was significantly associated with perception of efficacy and price among other factors. Respondents liked the price of ACT (33.3%) most, CQ was the drug most liked in terms of efficacy (44.2%) while SP was the drug most liked in terms of lack of side effect (38.9%), taste (61.6%) and convenience (35.7%).( P= 0.001)Conclusion: In addition to sustaining the current price control, there is a need to continuously monitor and effectively regulate the quality of the ACTs in circulation so as to gain the confidence of both the prescribers and the end users regarding efficacy and adherence to ACTs. This will help to safeguard the huge investment in ACT subsidy by the Roll Back Malaria partners.Key words: ACT, Subsidy, Affordable Medicines Facility-malari

    Helpers and egg investment in the cooperatively breeding acorn woodpecker: testing the concealed helper effects hypothesis

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    In cooperatively breeding acorn woodpeckers (Melanerpes formicivorus), helper males have a large positive effect on fledging success in good acorn crop years but only a small positive effect in poor acorn crop years, while helper females exhibit the opposite pattern. Based on these findings, we tested the “concealed helper effects” hypothesis, which proposes that laying females reduce investment in eggs (with respect to their size, number, or quality) in a way that confounds helper effects and results in an absence of a relationship between helpers and breeding success. Results generally failed to support the hypothesis. Mean egg size was positively related to temperatures during the 10 days prior to egg-laying and negatively related to the food supply as indexed by the prior fall’s acorn crop, but there were no significant differences vis-à-vis helpers except for interactions with the acorn crop that only partly corresponded to those predicted. With respect to clutch size, females laid larger clutches when assisted by female helpers, opposite the pattern predicted. Although our results suggest that egg size is adjusted to particular ecological circumstances, we conclude that neither egg nor clutch size is adjusted in a way that confounds the apparent effects of helpers, as proposed by the concealed helper effects hypothesis
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