High damage potential of seed-borne spot blotch in organically grown spring barley in Denmark

Spot blotch of barley (Bipolaris sorokiniana, perfect state: Cochliobolus sativus) occurs wherever barley is grown but is normally not considered a major problem in Danish barley production. It is therefore not included in routine disease surveys or official variety testing in Denmark. However, recommended seed contamination thresholds are 30% for spring barley and 15% for winter barley. Several spring barley varieties were grown under organic (no seed dressing, mechanical weeding) and conventional (seed dressing with fungicides, herbicide application) production conditions at three sites in Denmark in 2003. The harvested seeds were analysed for contamination levels of seed-borne B. sorokiniana using a blotter method. The percentage of seeds contaminated with B. sorokiniana ranged from about 5 to 95 % and was highly depending on the site, production system and variety. Contamination levels of organically cultivated plots were about twice as high as those of plots receiving conventional treatments. The germinating ability of seeds was highly affected by the level of B. sorokiniana contamination and declined drastically at contamination levels above 60%. This effect appeared to differ among varieties. The 1000-grain weight was not affected by the level of spot blotch contamination of seeds. The results indicate that the importance of spot blotch may be underrated, especially in organic barley production and that the role of varietal resistance should be investigated. More results are expected from ongoing seed analyses

Dual Labour Markets and Menu Costs: Explaining the Cyclicality of Productivity and Wage Differentials

The conventional menu cost framework performs poorly with realistic labour supply elasticities; the menu costs required for price rigidity are very high and the welfare consequences of monetary disturbances are negligible. We show that the presence of dual labour markets greatly improves the performance of the framework both by reducing menu cost requirements and by boosting the welfare consequences. In addition, the introduction of dual labour markets provides an explanation of procyclical productivity and the shrinking of wage differentials during booms, in line with stylized facts on business cycles.

Resistente bygsorter begrænser problemer med bladplet i økologisk såsæd

Seed born net blotch is a threat to the organic barley seed production in Denmark because it often exceeds the legal 15% infestation threshold in organically produced barley seed lots. Relationships among initial seed infestation levels, disease development during the growing season, yield parameters and net blotch infestation of the harvested grains were examined. Highly significant positive correlations among initial seed infestation, primary infection of seedlings and disease severity during the growing season as well as among disease severity at flowering and infestation of the harvested grains were found. The seed infestation level was much less than proportionally related to the primary infection of seedlings and to the disease severity later in the season. All these variables were negatively correlated with single grain weight, fraction of large grains and total yield. Varietal resistance appeared to be a key determinant for disease severity and seed infestation. The results will be used to help develop more flexible net blotch infestation thresholds for organically produced barley seeds

Nanoflow hydrodynamics

We show by nonequilibrium molecular dynamics simulations that the Navier-Stokes equation does not correctly describe water flow in a nanoscale geometry. It is argued that this failure reflects the fact that the coupling between the intrinsic rotational and translational degrees of freedom becomes important for nanoflows. The coupling is correctly accounted for by the extended Navier-Stokes equations that include the intrinsic angular momentum as an independent hydrodynamic degree of freedom

Control and femtosecond time-resolved imaging of torsion in a chiral molecule

We study how the combination of long and short laser pulses, can be used to induce torsion in an axially chiral biphenyl derivative (3,5-difluoro-3',5'-dibromo-4'-cyanobiphenyl). A long, with respect to the molecular rotational periods, elliptically polarized laser pulse produces 3D alignment of the molecules, and a linearly polarized short pulse initiates torsion about the stereogenic axis. The torsional motion is monitored in real-time by measuring the dihedral angle using femtosecond time-resolved Coulomb explosion imaging. Within the first 4 picoseconds, torsion occurs with a period of 1.25 picoseconds and an amplitude of 3 degrees in excellent agreement with theoretical calculations. At larger times the quantum states of the molecules describing the torsional motion dephase and an almost isotropic distribution of the dihedral angle is measured. We demonstrate an original application of covariance analysis of two-dimensional ion images to reveal strong correlations between specific ejected ionic fragments from Coulomb explosion. This technique strengthens our interpretation of the experimental data.Comment: 11 pages, 9 figure

Alterations in hypothalamic gene expression following Roux-en-Y gastric bypass

Objective: The role of the central nervous system in mediating metabolic effects of Roux-en-Y gastric bypass (RYGB) surgery is poorly understood. Using a rat model of RYGB, we aimed to identify changes in gene expression of key hypothalamic neuropeptides known to be involved in the regulation of energy balance. Methods: Lean male Sprague-Dawley rats underwent either RYGB or sham surgery. Body weight and food intake were monitored bi-weekly for 60 days post-surgery. In situ hybridization mRNA analysis of hypothalamic AgRP, NPY, CART, POMC and MCH was applied to RYGB and sham animals and compared with ad libitum fed and food-restricted rats. Furthermore, in situ hybridization mRNA analysis of dopaminergic transmission markers (TH and DAT) was applied in the midbrain. Results: RYGB surgery significantly reduced body weight and intake of a highly palatable diet but increased chow consumption compared with sham operated controls. In the arcuate nucleus, RYGB surgery increased mRNA levels of orexigenic AgRP and NPY, whereas no change was observed in anorexigenic CART and POMC mRNA levels. A similar pattern was seen in food-restricted versus ad libitum fed rats. In contrast to a significant increase of orexigenic MCH mRNA levels in food-restricted animals, RYGB did not change MCH expression in the lateral hypothalamus. In the VTA, RYGB surgery induced a reduction in mRNA levels of TH and DAT, whereas no changes were observed in the substantia nigra relative to sham surgery. Conclusion: RYGB surgery increases the mRNA levels of hunger-associated signaling markers in the rat arcuate nucleus without concomitantly increasing downstream MCH expression in the lateral hypothalamus, suggesting that RYGB surgery puts a brake on orexigenic hypothalamic output signals. In addition, down-regulation of midbrain TH and DAT expression suggests that altered dopaminergic activity also contributes to the reduced intake of palatable food in RYGB rats. Keywords: Roux-en-Y gastric bypass, Energy homeostasis, Hypothalamus, Hedonic, Mesolimbic pathwa