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Infections of Neonectria ditissima, the cause of European fruit tree canker, may be initiated during propagation. In a survey of 19 commercial apple orchards in southern Norway in the year of planting or the following year, the graft-union area of 15,270 trees was examined. The disease was found in 53% of the orchards, at a low incidence (

It has been hypothesized that a condensed nervous system with a medial ventral nerve cord is an ancestral character of Bilateria. The presence of similar dorsoventral molecular patterns along the nerve cords of vertebrates, flies, and an annelid has been interpreted as support for this scenario. Whether these similarities are generally found across the diversity of bilaterian neuroanatomies is unclear, and thus the evolutionary history of the nervous system is still contentious. Here we study representatives of Xenacoelomorpha, Rotifera, Nemertea, Brachiopoda, and Annelida to assess the conservation of the dorsoventral nerve cord patterning. None of the studied species show a conserved dorsoventral molecular regionalization of their nerve cords, not even the annelid Owenia fusiformis, whose trunk neuroanatomy parallels that of vertebrates and flies. Our findings restrict the use of molecular patterns to explain nervous system evolution, and suggest that the similarities in dorsoventral patterning and trunk neuroanatomies evolved independently in Bilateria.

Fungi within the Colletotrichum acutatum species complex occur asymptomatically on plant parts of many different plant species. Leaves from apple orchards in southern Norway were sampled, frozen for five hours and incubated for six days to reveal presence of asymptomatic infections of C. acutatum. Number of leaves (incidence) and leaf area covered (severity) with conidial masses of C. acutatum were assessed biweekly on cv. Aroma from late May to late September during three growing seasons. The first finding of conidial masses occurred in the second half of July, and there was a higher incidence occurring in August and September. Sampling of leaves from fruit spurs and vegetative shoots of cvs. Aroma and Elstar showed that conidial masses of C. acutatum developed on leaves on both shoot types, and there was no difference in incidence between these two types. The fungus was detected on leaves from six of eight commercial orchards of cv. Aroma over three years, with a mean incidence of 5.5 %. After storage, bitter rot was found on apple fruit from all eight orchards. There was no correlation between incidence of conidial masses of C. acutatum on leaves and on fruit. In all orchards and seasons investigated, incidence and severity on leaves varied from 0 to 67 % and 0 to 85 %, respectively. The discovery of apple leaves containing conidial masses of C. acutatum clearly indicate for leaves as a potential source of inoculum for fruit infections.

Background Medically unexplained symptoms (MUS) are a common yet challenging encounter in primary care. The aim of this study was to explore how general practitioners (GPs) understand and handle MUS. Methods Three focus group interviews were conducted with a total of 23 GPs. Participants with varied clinical experience were purposively recruited. The data were analysed thematically, using the concept of framing as an analytical lens. Results The GPs alternated between a biomedical frame, centred on disease, and a biopsychosocial frame, centred on the sick person. Each frame shaped the GPs’ understanding and handling of MUS. The biomedical frame emphasised the lack of objective evidence, problematized subjective patient testimony, and manifested feelings of uncertainty, doubt and powerlessness. This in turn complicated patient handling. In contrast, the biopsychosocial frame emphasised clinical experience, turned patient testimony into a valuable source of information, and manifested feelings of confidence and competence. This in turn made them feel empowered. The GPs with the least experience relied more on the biomedical frame, whereas their more seasoned seniors relied mostly on the biopsychosocial frame. Conclusion The biopsychosocial frame helps GPs to understand and handle MUS better than the biomedical frame does. Medical students should spend more time learning biopsychosocial medicine, and to integrate the clinical knowledge of their peers with their own. Electronic supplementary material The online version of this article (10.1186/s12875-018-0745-2) contains supplementary material, which is available to authorized users.

Leaves of sweet cherry, exposed to either paraquat or freezing to quickly senesce the leaf tissue, were incubated in about 100% RH at 25°C for 6 d. Sporulating colonies of Colletotrichum acutatum, the cause of anthracnose, developed on up to 100% of the paraquat-treated and frozen leaves, and on none of the untreated controls. Number of leaves and leaf area containing C. acutatum on naturally infected leaves increased over time from May to September. Mean incidence of C. acutatum on leaf blades on fruit spurs and vegetative shoots from eight orchard/year samplings were 41 and 33%, respectively. Secondary conidiation (formation of short hyphae and new conidia) from conidia applied to detached leaves took place 6 h after inoculation, but only up to 3% of the conidia formed new conidia. It may be concluded that asymptomatic sweet cherry leaves frequently host C. acutatum and may be a potential inoculum source for cherry fruit.

In the current work, we use the Constant Volume model and the numerical method, Regularized Smoothed Particle Hydrodynamics (RSPH) to study propagation and reflection of blast waves from detonations of the high explosives C-4 and TNT. The results from simulations of free-field TNT explosions are compared to previously published data, and good agreement is found. Measurements from height of burst tests performed by the Norwegian Defence Estates Agency are used to compare against numerical simulations. The results for shock time of arrival and the pressure levels are well represented by the numerical results. The results are also found to be in good agreement with results from a commercially available code. The effect of allowing different ratios of specific heat capacities in the explosive products are studied. We also evaluate the effect of changing the charge shape and height of burst on the triple point trajectory.

In many shock wave problems, the assumption of cylinder symmetry is useful, and allows 3D situations to be simulated with a 2D numerical code, thereby reducing computational cost, and increasing computational speed. In this paper we use the regularized smoothed particle hydrodynamics (RSPH) description for cylinder symmetry (Omang in “A numerical study of shock reflection phenomena. Exploring the capabilities of regularized smoothed particle hydrodynamics to handle shock waves”, 2005; Omang et al. in Shock Waves 14(4):293–298, 2005; Omang et al. in J Comput Phys 213(1):391–412, 2006) to study 3D shock reflection and shock interaction phenomena. In the first example we study the shock reflection pattern resulting from a torus-shaped shock reflecting both from the symmetry axis and from an object in the flow field. At the symmetry axis a characteristic Mach reflection is formed, with a triple point, a curved Mach stem, and a weak slip layer. The shock also interacts with the object, producing additional reflected shocks. The interactions between the different shock waves, resulting for instance in strong local pressure and density peaks, are studied in closer detail.

In this paper we wish to demonstrate to what extent the numerical method regularized smoothed particle hydrodynamics (RSPH) is capable of modelling shocks and shock reflection patterns in a satisfactory manner. The use of SPH based methods to model shock wave problems has been relatively sparse, both due to historical reasons, as the method was originally developed for studies of astrophysical gas dynamics, but also due to the fact that boundary treatment in Lagrangian methods may be a difficult task. The boundary conditions have therefore been given special attention in this paper. Results presented for one quasi-stationary and three non-stationary flow tests reveal a high degree of similarity, when compared to published numerical and experimental data. The difference is found to be below 5, in the case where experimental data was found tabulated. The transition from regular reflection (RR) to Mach reflection (MR) and the opposite transition from MR to RR are studied. The results are found to be in close agreement with the results obtained from various empirical and semi-empirical formulas published in the literature. A convergence test shows a convergence rate slightly steeper than linear, comparable to what is found for other numerical methods when shocks are involved.

In this paper we present an alternative generic kernel function for use in Smoothed Particle Hydrodynamics (SPH) based methods. The alternative kernel has been implemented in a standard Cartesian description, and the results for the Sod shock tube problem is presented both with the alternative kernel and the traditional B-spline kernel. Kernels for cylindrically symmetric systems are developed based on fundamental interpolation theory for the cylindrical symmetry. A set of modified equations of motions are further derived through the use of Lagrangian formalism. Previous results have shown that the use of the traditional B-spline kernel function as a generic kernel implies that the cylindrically symmetric solution must be solved by table interpolation. By introducing an alternative generic kernel function, we derive simple analytical solution also for cylindrically symmetric systems. When compared to the B-spline function, the computational efficiency has been increased and the results improved. The results show good agreement with the analytical solution both for the Noh infinite shock problem and the Sedov point source explosion.

Cluster models are constructed for mono- and dinuclear Cr(II) sites and mononuclear Cr(III) sites on the Cr/SiO2 Phillips catalyst and used to compute d–d transition energies and intensities. Mononuclear pseudo-tetrahedral Cr(II) gives rise to two bands of electric-dipole-allowed d–d transitions, at 8,400 and 12,300 cm−1. This doublet is lowered in energy and intensity as the bond angle about chromium, ∠OCrO, opens up. The dinuclear site gives rise to bands at 5,200 and 10,300 cm−1, consistent with calculations for a mononuclear cluster of comparable value for ∠OCrO. A tri-coordinated Cr(III) cluster shows bands of comparable oscillator strengths at energies of 11,000, 16,000, 18,000–20,000 and 33,000 cm−1. The predicted bands correspond well with d–d bands in experimental diffuse reflectance spectra.

The PM3(tm) method has been applied to several systems of relevance to catalytic polymerization of olefins, for catalysts containing Ti, Zr or Cr. With some exceptions, PM3(tm) calculations reproduce experimental geometries of stable, closed-shell, precursors well. For stationary points along the path of monomer insertion into a metal-alkyl bond, the comparison is made to structures obtained by optimization using various first-principle methods. Large errors are uncovered for the transient structures, in particular pertaining to metal-ethylene coordination and agostic interactions. The energy profiles for four insertion reactions are computed by gradient-corrected density functional (DFTG) methods, using molecular structures taken from PM3(tm) and first-principle geometry optimizations, respectively. The chromium case is promising, giving values for the barrier to monomer insertion of 11 and 9 kcal/mol based on PM3(tm) and DFTG geometries, respectively. The Ti- and Zr-based systems are predicted to proceed downhill based on PM3(tm) structures, whereas small barriers are found when using first-principle structures. A hybrid PM3(tm)-DFTG procedure is suggested for geometry optimization, which facilitates an accurate estimate of the barrier when applied to one of the zirconium systems.

The dependence of the electron capture cross section on cluster size in proton-cluster collisions is investigated within two different theoretical models. At low collision velocities a strong increase in the cross section with cluster size is found, whereas the size-dependency of the cross section becomes less pronounced at higher velocities.

Binary mixed monomolecular films of poly(benzyl-methacrylate) and arachidic acid at the water/air interface have been studied with respect to compatibility and stability. The surface pressure — area isotherms indicate compatibility of the two components. However, the miscible state is unstable at high surface pressures. This is demonstrated by the constant pressure relaxation of the mixtures. There is a mechanism of separation and nucleation of the arachidic acid from the film for mixtures with high polymer content at a surface pressure of 30 mN/m. For lower concentrations of polymer in the mixtures and at a surface pressure of 20 mN/m the fatty acid is stabilized by the polymer.

The electronic spectrum of O2− is reinvestigated using CASSCF and CI methods. In particular, a previously noted curious flattening of theA2Πu curve has been studied in detail. The present analysis disagrees with the previous one where this flattening was found to be a result of an avoided curve crossing between a valence and a Rydberg state of O2−. A simple procedure is suggested to determine whether a wavefunction is of real Rydberg character or if the bound character of the state is just an artefact of the calculation.