Nitrogen and ultraviolet radiation modify grapevines’ susceptibility to powdery mildew

Potted Cabernet Sauvignon and Chardonnay grapevines were grown in southeastern Australia under either ambient or reduced ultraviolet (UV) radiation to test the effect of UV on powdery mildew (Uncinula necator) susceptibility. Diacetate films were used to screen out UV-B (280-315 nm) and UV-A (315-400 nm). Two nitrogen treatments (0 or 3 g N per plant) were applied at bloom to test interactions of nitrogen status with UV radiation. Cabernet Sauvignon was much less susceptible to U. necator and also responded less to UV and nitrogen. U. necator incidence and severity on leaves were increased dramatically when high nitrogen supply was combined with low UV, particularly in Chardonnay. The differences in infection were not due to variation in canopy microclimate (temperature and humidity) caused by experimental treatments. However, high disease susceptibility in response to high nitrogen status and low UV radiation was related to low concentrations of constitutive phenolic compounds (flavonol glycosides and, to a lesser extent, hydroxy-cinnamic acid derivatives), high leafnitrogen status and photosynthetic rates, high succulence, and reduced cuticular wax deposition. No stilbene phytoalexins could be detected following infection, suggesting that stilbenes are not involved in U. necator resistance in grapevines. These results show that UV radiation affects disease susceptibility of grapevine cultivars and that this susceptibility is modulated by nitrogen supply

Non-monotonous crossover between capillary condensation and interface localisation/delocalisation transition in binary polymer blends

Within self-consistent field theory we study the phase behaviour of a symmetric binary AB polymer blend confined into a thin film. The film surfaces interact with the monomers via short range potentials. One surface attracts the A component and the corresponding semi-infinite system exhibits a first order wetting transition. The surface interaction of the opposite surface is varied as to study the crossover from capillary condensation for symmetric surface fields to the interface localisation/delocalisation transition for antisymmetric surface fields. In the former case the phase diagram has a single critical point close to the bulk critical point. In the latter case the phase diagram exhibits two critical points which correspond to the prewetting critical points of the semi-infinite system. The crossover between these qualitatively different limiting behaviours occurs gradually, however, the critical temperature and the critical composition exhibit a non-monotonic dependence on the surface field.Comment: to appear in Europhys.Let

Spatiotemporal changes in the accumulation of sugar and potassium within individual 'Sauvignon Blanc' (Vitis vinifera L.) berries

It has been speculated that there may be a link between the transport of sugar and potassium into grape berries during ripening as they exhibit similar accumulation patterns. It is unclear if this proposed link is apparent in individual grape berries and in the grape berry compartments. Single grape berries were therefore analysed for sugar and potassium content and concentration within the skin, seeds and the pulp from pre-véraison until harvest. Sugar and potassium had similar accumulation patterns and positive relationships were confirmed between the sugar and potassium content within individual berries and compartments. The sugar content in the grape berry, however, increased 5-fold during ripening whereas the potassium content only doubled. Both sugar and potassium increased with berry size, suggesting a ternary relationship with berry water. The high variability in sugar and potassium contents between berries however affirms plasticity in their accumulation within individual berries

Impact of dynamic changes in MELD score on survival after liver transplantation : a Eurotransplant registry analysis

Background & Aims: With restricted numbers of available organs, futility in liver transplantation has to be avoided. The concept of dynamic changes in MELD score (DeltaMELD) has previously been shown to be a simple tool to identify patients with the greatest risk of death after transplantation. Aim was to validate this concept with the Eurotransplant (ET) database. Methods: A retrospective registry analysis was performed on all patients listed for liver transplantation within ET between 2006 and 2011. Patients <18 years of age, acute liver failure, malignancy and patients listed for retransplantation were excluded. Influence of MELD at listing (MELDon), MELD at transplantation (MELDoff), DeltaMELD, age, sex, underlying disease and time on the waiting list on overall survival after liver transplantation were evaluated. Results: A total of 16 821 patients were listed for liver transplantation, 8096 met the inclusion criteria. Age, MELD on and DeltaMELD showed significant influence on survival on the waiting list. Age and DeltaMELD showed influence on survival after liver transplantation, with DeltaMELD>10 showing a 1.6-fold increased risk of death. Conclusion: The concept of DeltaMELD was validated in a large, prospective data set. It provides a simple tool to identify patients with increased risk of death after liver transplantation and might help improve long-term results

Effect of Gravity and Confinement on Phase Equilibria: A Density Matrix Renormalization Approach

The phase diagram of the 2D Ising model confined between two infinite walls and subject to opposing surface fields and to a bulk "gravitational" field is calculated by means of density matrix renormalization methods. In absence of gravity two phase coexistence is restricted to temperatures below the wetting temperature. We find that gravity restores the two phase coexistence up to the bulk critical temperature, in agreement with previous mean-field predictions. We calculate the exponents governing the finite size scaling in the temperature and in the gravitational field directions. The former is the exponent which describes the shift of the critical temperature in capillary condensation. The latter agrees, for large surface fields, with a scaling assumption of Van Leeuwen and Sengers. Magnetization profiles in the two phase and in the single phase region are calculated. The profiles in the single phase region, where an interface is present, agree well with magnetization profiles calculated from a simple solid-on-solid interface hamiltonian.Comment: 4 pages, RevTeX and 4 PostScript figures included. Final version as published. To appear in Phys. Rev. Let

Potassium in the grape (Vitis vinifera L.) berry: transport and function

K⁺ is the most abundant cation in the grape berry. Here we focus on the most recent information in the long distance transport and partitioning of K⁺ within the grapevine and postulate on the potential role of K⁺ in berry sugar accumulation, berry water relations, cellular growth, disease resistance, abiotic stress tolerance and mitigating senescence. By integrating information from several different plant systems we have been able to generate new hypotheses on the integral functions of this predominant cation and to improve our understanding of how these functions contribute to grape berry growth and ripening. Valuable contributions to the study of K⁺ in membrane stabilization, turgor maintenance and phloem transport have allowed us to propose a mechanistic model for the role of this cation in grape berry development.Suzy Y. Rogiers, Zelmari A. Coetzee, Rob R. Walker, Alain Deloire and Stephen D. Tyerma

Glauber Critical Dynamics: Exact Solution of the Kinetic Gaussian Model

In this paper, we have exactly solved Glauber critical dynamics of the Gaussian model on three dimensions. Of course, it is much easy to apply to low dimensional case. The key steps are that we generalize the spin change mechanism from Glauber's single-spin flipping to single-spin transition and give a normalized version of the transition probability . We have also investigated the dynamical critical exponent and found surprisingly that the dynamical critical exponent is highly universal which refer to that for one- two- and three-dimensions they have same value independent of spatial dimensionality in contrast to static (equilibrium) critical exponents.Comment: 9 page

Potassium in the Grape (Vitis vinifera L.) Berry: Transport and Function

K+ is the most abundant cation in the grape berry. Here we focus on the most recent information in the long distance transport and partitioning of K+ within the grapevine and postulate on the potential role of K+ in berry sugar accumulation, berry water relations, cellular growth, disease resistance, abiotic stress tolerance and mitigating senescence. By integrating information from several different plant systems we have been able to generate new hypotheses on the integral functions of this predominant cation and to improve our understanding of how these functions contribute to grape berry growth and ripening. Valuable contributions to the study of K+ in membrane stabilization, turgor maintenance and phloem transport have allowed us to propose a mechanistic model for the role of this cation in grape berry development

Solvable Kinetic Gaussian Model in External Field

In this paper, the single-spin transition dynamics is used to investigate the kinetic Gaussian model in a periodic external field. We first derive the fundamental dynamic equations, and then treat an isotropic d-dimensional hypercubic lattice Gaussian spin system with Fourier's transformation method. We obtain exactly the local magnetization and the equal-time pair correlation function. The critical characteristics of the dynamical, the complex susceptibility, and the dynamical response are discussed. The results show that the time evolution of the dynamical quantities and the dynamical responses of the system strongly depend on the frequency and the wave vector of the external field.Comment: 11 page

Confinement Effects in Antiferromagnets

Phase equilibrium in confined Ising antiferromagnets was studied as a function of the coupling (v) and a magnetic field (h) at the surfaces, in the presence of an external field H. The ground state properties were calculated exactly for symmetric boundary conditions and nearest-neighbor interactions, and a full zero-temperature phase diagram in the plane v-h was obtained for films with symmetry-preserving surface orientations. The ground-state analysis was extended to the H-T plane using a cluster-variation free energy. The study of the finite-T properties (as a function of v and h) reveals the close interdependence between the surface and finite-size effects and, together with the ground-state phase diagram, provides an integral picture of the confinement in anisotropic antiferromagnets with surfaces that preserve the symmetry of the order parameter.Comment: 10 pages, 8 figures, Accepted in Phys. Rev.