Gjin taalsoarch yn de soarch. De rol fan Frysk en Meartaligens yn de soarch- en wolwêzenssektor yn Fryslân

The global attractivity of the rational difference equation yn = (yn-k + yn-m) / (1 + yn-k yn-m)

This paper studies global asymptotic stability for positive solutions to the equation yn = yn−k + yn−m 1 + yn−k yn−m , n = 0, 1, . . . , with y−m , y−m+1, . . . , y−1 ∈ (0,∞) and 1 ≤ k < m. The paper includes a discussion of stability for a wide class of symmetric rational difference equations which includes the type studied here as well as several other in the recent literature. c © 2006 Elsev...

(E)-1,5-Di­phenyl­pent-2-en-4-yn-1-one

The title compound, C17H12O, has an E conformation about the C=C bond. The C-C C-C torsion angle is 7.7 (2)°, and the mean planes of the phenyl-ethyl-enone [r.m.s. deviation = 0.059 (1) Å] and phenyl-acetyl-ene [r.m.s. deviation = 0.023 (1) Å] fragments form a dihedral angle of 14.16 (7)°. In the crystal, weak C-H⋯O inter-actions link the mol-ecules into zigzag chains propagated in [010].

Existence de la brucellose en Iran. Isolement de Brucella abortus

On the rational recursive sequence yn = A + yn-1/yn-m for small A

This work studies the existence of positive prime periodic solutions of higher order for rational recursive equations of the form yn = A + yn−1 yn−m , n = 0, 1, 2, . . . , with y−m , y−m+1, . . . , y−1 ∈ (0,∞) and m ∈ {2, 3, 4, . . .}. In particular, we show that for sufficiently small A > 0, there exist periodic solutions with prime period 2m +Um + 1, for almost all m, where Um = max{i ∈ N : i...

(2,5-Diphenyl­pent-4-yn-1-en-3-yl­idene)triphenyl­phospho­rane

The title compound, C(45)H(27)P, was obtained as a product of the reaction of triphenyl-methyl-enephospho-rane with one molar equivalent of 1,4-diphenyl-butadiyne in toluene. The compound was very stable under ambient conditions, but rapidly decomposed in solution when exposed to the air. The P atom is tetra-coordinated in an approximately tetrahedral geometry. The length of the C C triple bond...