2,268 research outputs found

    Ramanujan and Extensions and Contractions of Continued Fractions

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    If a continued fraction Kn=1an/bnK_{n=1}^{\infty} a_{n}/b_{n} is known to converge but its limit is not easy to determine, it may be easier to use an extension of Kn=1an/bnK_{n=1}^{\infty}a_{n}/b_{n} to find the limit. By an extension of Kn=1an/bnK_{n=1}^{\infty} a_{n}/b_{n} we mean a continued fraction Kn=1cn/dnK_{n=1}^{\infty} c_{n}/d_{n} whose odd or even part is Kn=1an/bnK_{n=1}^{\infty} a_{n}/b_{n}. One can then possibly find the limit in one of three ways: (i) Prove the extension converges and find its limit; (ii) Prove the extension converges and find the limit of the other contraction (for example, the odd part, if Kn=1an/bnK_{n=1}^{\infty}a_{n}/b_{n} is the even part); (ii) Find the limit of the other contraction and show that the odd and even parts of the extension tend to the same limit. We apply these ideas to derive new proofs of certain continued fraction identities of Ramanujan and to prove a generalization of an identity involving the Rogers-Ramanujan continued fraction, which was conjectured by Blecksmith and Brillhart.Comment: 16 page

    Lessons Learned in Pooling Data for Reference Populations

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    This study set out to demonstrate the feasibility of merging data from 4 different experimental resource dairy populations (1 herd in each of Scotland and Ireland, and 2 in the Netherlands) to create a pooled reference population for joint genetic and genomic analyses. Data included a total of 60,058 weekly records from 1,630 Holstein-Friesian cows across the 4 herds and included 7 traits: milk, fat and protein yield, milk somatic cell count, live weight, dry matter intake, and energy intake and balance. Missing records were predicted using random regression models, so that at the end there were 44 weekly records, corresponding to the typical 305-day lactation, for each cow. Data were subsequently merged and analysed with mixed linear models. Genetic variance and heritability estimates were greater (P0.05) from zero. When estimable, the genetic correlation between herds for the same trait ranged from 0.85 to 0.99. Results suggested that merging experimental herd data into a single dataset is both feasible and sensible, despite potential differences in management and recording of the animals in the four herds. Merging experimental data will increase the precision of parameter estimates in a genetic analysis and augment the potential reference population in genome-wide association studies especially of difficult-to-record traits
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