Empirical codes for prediction of vortex induced vibrations need reliable data for hydrodynamic coefficients. Such data are almost exclusively based on measured forces on rigid cylinders that have forced harmonic motions in cross-flow (CF) or in-line (IL) directions. This type of experiment is not able to capture all effects that could be important for realistic cross section motions of slender beams due to two reasons: 1. Slender beams will normally have combined IL and CF oscillations. 2. Higher order frequency components will normally be present for vibrating beams. It is difficult to measure local forces on short segments of flexible beams in laboratory tests due to the small diameters. The most convenient instrumentation is to use a large number of strain gauges or accelerometers along the beam. Proper data processing will then give reliable data for the motions, which means that the trajectory of cross sections can be found. Hence, the following set of experiments can be carried out in order to find hydrodynamic coefficients under realistic VIV conditions: 1. Experiments with a slender flexible beam and processing of recorded strains or accelerometers to identify cross section trajectories. 2. Measurement of forces on a rigid cylinder section with forced motions. Reynolds number, amplitude ratio, orbit shape and non-dimensional frequency must be identical in the flexible beam and rigid cylinder tests. Such experiments have been carried out, and the results are presented in terms of hydrodynamic coefficients for combined CF and IL oscillations. Coefficients are found for the primary CF and IL frequencies, but also for higher order frequency components. Results are presented and discussed in relation to well known results from pure CF and IL oscillations. One way of verifying that the coefficients have been correctly identified, is to apply the coefficients in an empirical response model and compare analysis results to the observation. This step has, however, not been carried out so far.

Successful interspecific hybrids were obtained through hybridization between cultivated sunflower (Helianthus annuus L.; 2n=2x=34) variety ARM-243B and a wild species (H. argophyllus; 2n=2x=34) accession no. PI-468649 for transferring desirable traits like downy mildew resistance, oil content and hopper resistance from wild species into cultivated background. Morphological, cytological and simple sequence repeats (SSR)-based molecular analyses were carried out to confirm the hybrid nature of the F 1 plants. The hybrids exhibited morphological features intermediate to both the parents for few attributes and showed greater similarity to wild Helianthus species for traits like leaf and stem hairiness, flower colour, stem size, branching, disc floret pigmentation, plant height, seed size and seed shape, etc. A reduction (89.9%) in pollen fertility was recorded in F 1 plants. Meiotic analysis revealed the presence of univalents, bivalents, trivalents and quadrivalents in all the pollen mother cells (PMCs) analysed. Multivalents were observed in few PMCs, indicating segmental homology between chromosomes. Higher level of chromosome configurations like quadrivalents were observed in 42 out of 50 PMCs. Frequently observed chromosome configurations in diakinensis were 15 II + 1 IV and 13 II + 2 IV. The results suggested that the species H. argophyllus and H. annuus differ by 1-2 translocations. SSR primers ORS-05, ORS-896 and ORS-908 were found to reveal highly polymorphic bands in the parents.

Identification of genes expressed during the Golovinomyces orontii infection process in Helianthus niveus assumes importance for incorporation of resistance to powdery mildew in cultivated sunflower (H. annuus L.) from this donor species. RNA-seq analysis of control (uninfected) and infected samples of H. niveus resulted in identification of 231,754 transcripts. A total of 3726 transcripts were differentially expressed of which 205 were specifically expressed in control and 1961 in infected samples. Functional annotation of the differentially expressed transcripts showed significant upregulation of GRAS type transcription factor (TF) and plant specific GATA-type zinc finger TF in infected samples and the K-box, MADS box TF and WRKY family TF in control tissues. Gene ontology classification showed that genes involved in cell and cell part functioning, catalytic and metabolic processes were significantly and highly expressed. This is the first application of RNA-Seq for identification of key genes and pathways involved in powdery mildew infection process in a Helianthus species conferring resistance to the pathogen.

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Pipelines are the most convenient and safe medium of oil and gas transportation from offshore fields. Such pipelines will often have free spans when passing through areas with uneven sea floor. These free spans may experience vibrations due to vortex shedding when subjected to ocean current, which may lead to unacceptable accumulation of fatigue damage. The bottom topography may result in multi-span pipelines with short contact area between adjacent spans. Such neighbor spans may interact dynamically, meaning that the response of one span can not be found unless its neighbors are taken into account. The purpose of the present paper is to illustrate possible consequences of interaction and present a consistent method for classification of interaction. Two aspects of interaction are studied, namely the possible energy transfer due to hydrodynamic forces from one span to its neighbor of different length, and how the stiffness properties and length of the contact area between spans influence the interaction. The first aspect is studied by using an empirical model for the analysis of vortex induced vibrations (VIV) of multi-span pipelines. This model applies a frequency domain solution procedure that must describe the interaction between the pipe and the seafloor by linear theory. It was observed from the results that the spans interact dynamically, and the distribution of lift forces along the length of pipe shows that energy is transferred from the span with smallest amplitude to the span with largest amplitude. The second aspect is studied by use of an analysis model where the contact between pipe and seafloor has a more realistic representation. This model is based on a non-linear finite element method, and the dynamic analysis is carried out in time domain. By using this model it is possible to characterize the mechanical coupling between the spans. A systematic study illustrates how seafloor stiffness and local profile of the seafloor will influence the interaction.