Helical Magnetic Fields from Inflation

We analyze the generation of seed magnetic fields during de Sitter inflation considering a non-invariant conformal term in the electromagnetic Lagrangian of the form $-\frac14 I(\phi) F_{\mu \nu} \widetilde{F}^{\mu \nu}$, where $I(\phi)$ is a pseudoscalar function of a non-trivial background field $\phi$. In particular, we consider a toy model, that could be realized owing to the coupling between the photon and either a (tachyonic) massive pseudoscalar field and a massless pseudoscalar field non-minimally coupled to gravity, where $I$ follows a simple power-law behavior $I(k,\eta) = g/(-k\eta)^{\beta}$ during inflation, while it is negligibly small subsequently. Here, $g$ is a positive dimensionless constant, $k$ the wavenumber, $\eta$ the conformal time, and $\beta$ a real positive number. We find that only when $\beta = 1$ and $0.1 \lesssim g \lesssim 2$ astrophysically interesting fields can be produced as excitation of the vacuum, and that they are maximally helical.Comment: 17 pages, 1 figure, subsection IIc and references added; accepted for publication in IJMP

QCD with light Wilson quarks on fine lattices (I): first experiences and physics results

Recent conceptual, algorithmic and technical advances allow numerical simulations of lattice QCD with Wilson quarks to be performed at significantly smaller quark masses than was possible before. Here we report on simulations of two-flavour QCD at sea-quark masses from slightly above to approximately 1/4 of the strange-quark mass, on lattices with up to 64x32^3 points and spacings from 0.05 to 0.08 fm. Physical sea-quark effects are clearly seen on these lattices, while the lattice effects appear to be quite small, even without O(a) improvement. A striking result is that the dependence of the pion mass on the sea-quark mass is accurately described by leading-order chiral perturbation theory up to meson masses of about 500 MeV.Comment: TeX source, 17 pages, figures include

Competitive percolation strategies for network recovery

Restoring operation of critical infrastructure systems after catastrophic events is an important issue, inspiring work in multiple fields, including network science, civil engineering, and operations research. We consider the problem of finding the optimal order of repairing elements in power grids and similar infrastructure. Most existing methods either only consider system network structure, potentially ignoring important features, or incorporate component level details leading to complex optimization problems with limited scalability. We aim to narrow the gap between the two approaches. Analyzing realistic recovery strategies, we identify over- and undersupply penalties of commodities as primary contributions to reconstruction cost, and we demonstrate traditional network science methods, which maximize the largest connected component, are cost inefficient. We propose a novel competitive percolation recovery model accounting for node demand and supply, and network structure. Our model well approximates realistic recovery strategies, suppressing growth of the largest connected component through a process analogous to explosive percolation. Using synthetic power grids, we investigate the effect of network characteristics on recovery process efficiency. We learn that high structural redundancy enables reduced total cost and faster recovery, however, requires more information at each recovery step. We also confirm that decentralized supply in networks generally benefits recovery efforts.Comment: 14 pages, 6 figure

Suplemento alimenticio en colonias de abejas para la mejora del servicio de polinización de kiwi (Actinidia deliciosa Liang & Ferguson) (Actinidiaceae: Theales)

El modelo actual de agricultura determina una disminución en los hábitats seminaturales lo que conduce a una mala nutrición de las colonias de abejas, las cuales generalmente necesitan ser suplementadas con alimentos. Las abejas se utilizan para transferir polen entre plantas de kiwi (Actinidia deliciosa Liang & Ferguson masculina y femenina, aumentando así la calidad de la fruta y el rendimiento de los cultivos. El objetivo principal fue determinar el efecto de la estimulación de las colonias de Apis mellifera L. con suministros alimentarios estándar sobre la recolección de polen de kiwi. Los tratamientos (n= 5 colmenas cada uno) se realizaron en un huerto de kiwis en Mar del Plata, Argentina: Grupo J/A: suministrado con jarabe de azúcar (2:1) + suplemento proteico líquido (“Apipromotor®”); Grupo J/P: suministrado con jarabe de azúcar (2:1) + suplemento de proteínas sólidas ("patty"); Grupo J: suministrado con jarabe de azúcar (2:1); Grupo C: control, no suministrado. Las colonias abastecidas con J, J/P y J/A recolectaron más polen de kiwifruit que el tratamiento control, incluso bajo la presencia de otras especies florales en áreas cercanas. Aunque las abejas recolectaron la mayor parte del polen de otras especies de plantas de hábitats seminaturales, los tratamientos bajo estimulación artificial (J/P, J/A y J) pueden mejorar significativamente el servicio de polinización de kiwis que realizan las abejas.The current agriculture model determines a decrease in semi-natural habitats leading to poor nutrition for honeybee colonies, which usually need to be food supplemented. Honeybees are used to transfer pollen between male and female kiwifruit (Actinidia deliciosaLiang & Ferguson) plants, increasing fruit quality and crop yield. Our main goal was to determine the effect of stimulating Apis mellifera L. colonies with standard food supplies on the collection of kiwifruit pollen. However, honey bees can also forage other flowering species in the crop site´s surrounding areas. We selected kiwifruit as a model to analyze the effects of food supply on pollen collection of the target crop. The following experimental treatments (n = 5 hives each were conducted in a kiwifruit orchard in Mar del Plata, Argentina: Group J/A: supplied with sugar syrup (2:1 + liquid protein supplements ("Apipromotor ®"; Group J/P: supplied with sugar syrup (2:1 + solid protein supplements ("patty";Group J: supplied with sugar syrup (2:1; Group C: control, not supplied. Colonies supplied with J, J/P and J/A collected more kiwifruit pollen than the other two treatments, even under other flowering species in areas nearby. Although honeybees collected most pollen from other plant species of semi-natural habitats, J/P, J, and J/A treatments can significantly improve the honeybees´ kiwifruit pollination service.Fil: de Piano, Fiorella Giselle. Universidad Nacional de Mar del Plata. Instituto de Investigaciones En Produccion, Sanidad y Ambiente. - Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet - Mar del Plata. Instituto de Investigaciones En Produccion, Sanidad y Ambiente.; Argentina. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales; ArgentinaFil: Meroi Arcerito, Facundo René. Universidad Nacional de Mar del Plata. Instituto de Investigaciones En Produccion, Sanidad y Ambiente. - Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet - Mar del Plata. Instituto de Investigaciones En Produccion, Sanidad y Ambiente.; Argentina. Ministerio de Ciencia. Tecnología e Innovación Productiva. Agencia Nacional de Promoción Científica y Tecnológica; ArgentinaFil: De Feudis, Leonardo. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales; ArgentinaFil: Basilio, Alicia M.. Universidad de Buenos Aires. Facultad de Agronomía; ArgentinaFil: Galetto, Leonardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; ArgentinaFil: Eguaras, Martin Javier. Universidad Nacional de Mar del Plata. Instituto de Investigaciones En Produccion, Sanidad y Ambiente. - Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet - Mar del Plata. Instituto de Investigaciones En Produccion, Sanidad y Ambiente.; Argentina. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales; ArgentinaFil: Maggi, Matías Daniel. Universidad Nacional de Mar del Plata. Instituto de Investigaciones En Produccion, Sanidad y Ambiente. - Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet - Mar del Plata. Instituto de Investigaciones En Produccion, Sanidad y Ambiente.; Argentina. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales; Argentin

Reversible male sterility in eggplant

SummarySince decades, plant male sterility is considered a powerful tool for biological containment to minimize unwanted self‐pollination for hybrid seed production. Furthermore, prevention of pollen dispersal also answers to concerns regarding transgene flow via pollen from Genetically Modified (GM) crops to traditional crop fields or wild relatives. We induced male sterility by suppressing endogenous general transcription factor genes, TAFs, using anther‐specific promoters combined with artificial microRNA (amiRNA) technology (Schwab et al., 2006). The system was made reversible by the ethanol inducible expression of an amiRNA‐insensitive form of the target gene. We provide proof of concept in eggplant, a cultivated crop belonging to the Solanaceae family that includes many important food crops. The transgenic eggplants that we generated are completely male sterile and fertility can be fully restored by short treatments with ethanol, confirming the efficiency but also the reliability of the system in view of open field cultivation. By combining this system with induced parthenocarpy (Rotino et al., 1997), we provide a novel example of complete transgene containment in eggplant, which enables biological mitigation measures for the benefit of coexistence or biosafety purposes for GM crop cultivation

Translation and validation of an ageism scale for dental students in Switzerland

PURPOSE This study aimed to validate an ageism scale for dental students in Switzerland. METHODS The original scale was first translated to German and then evaluated by 14 experts for relevance; four items were eliminated. Validation of the resulting questionnaire was performed at three Swiss dental schools. Principal component analysis (PCA) was performed; Cronbach's alpha (α) was used to assess the internal consistency reliability, and Pearson's coefficient to identify any correlations with demographic parameters (P < 0.05). RESULTS PCA revealed 11 items among 4 factors (Overall: 11 items, α = 0.63, variance = 56.6%; Factor #1 (F1): items = 3, α = 0.64; Factor #2 (F2): items = 3, α = 0.42; Factor #3 (F3): items = 3, α = 0.35; Factor #4 (F4): items = 2, α = 0.37). F1 and F4 were correlated with clinical experience (F1: P = 0.042; F4: P = 0.006) and participation in a gerodontology course (F1: P = 0.021; F4: P = 0.004). F1 was correlated with experience of dealing with the elderly (P = 0.031), while residence locality was correlated with F3 (P = 0.047) and F4 (P = 0.043). F2 was correlated with the presence of elderly in the family (P = 0.047). CONCLUSION The translated dental ageism questionnaire for Switzerland resulted in an 11-item scale with acceptable reliability

QCD with light Wilson quarks on fine lattices (II): DD-HMC simulations and data analysis

In this second report on our recent numerical simulations of two-flavour QCD, we provide further technical details on the simulations and describe the methods we used to extract the meson masses and decay constants from the generated ensembles of gauge fields. Among the topics covered are the choice of the DD-HMC parameters, the issue of stability, autocorrelations and the statistical error analysis. Extensive data tables are included as well as a short discussion of the quark-mass dependence in partially quenched QCD, supplementing the physics analysis that was presented in the first paper in this series.Comment: TeX source, 35 pages, figures include

Platelet endothelial cell adhesion molecule-1 regulates collagen-stimulated platelet function by modulating the association of phosphatidylinositol 3-kinase with Grb-2-associated binding protein-1 and linker for activation of T cells

Background: Platelet activation by collagen depends on signals transduced by the glycoprotein (GP)VI–Fc receptor (FcR)-chain collagen receptor complex, which involves recruitment of phosphatidylinositol 3-kinase (PI3K) to phosphorylated tyrosines in the linker for activation of T cells (LAT). An interaction between the p85 regulatory subunit of PI3K and the scaffolding molecule Grb-2-associated binding protein-1 (Gab1), which is regulated by binding of the Src homology 2 domain-containing protein tyrosine phosphatase-2 (SHP-2) to Gab1, has been shown in other cell types to sustain PI3K activity to elicit cellular responses. Platelet endothelial cell adhesion molecule-1 (PECAM-1) functions as a negative regulator of platelet reactivity and thrombosis, at least in part by inhibiting GPVI–FcR-chain signaling via recruitment of SHP-2 to phosphorylated immunoreceptor tyrosine-based inhibitory motifs in PECAM-1. Objective: To investigate the possibility that PECAM-1 regulates the formation of the Gab1–p85 signaling complexes, and the potential effect of such interactions on GPVI-mediated platelet activation in platelets. Methods: The ability of PECAM-1 signaling to modulate the LAT signalosome was investigated with immunoblotting assays on human platelets and knockout mouse platelets. Results: PECAM-1-associated SHP-2 in collagen-stimulated platelets binds to p85, which results in diminished levels of association with both Gab1 and LAT and reduced collagen-stimulated PI3K signaling. We therefore propose that PECAM-1-mediated inhibition of GPVI-dependent platelet responses result, at least in part, from recruitment of SHP-2–p85 complexes to tyrosine-phosphorylated PECAM-1, which diminishes the association of PI3K with activatory signaling molecules, such as Gab1 and LAT