Majorana spinors and extended Lorentz symmetry in four-dimensional theory

An extended local Lorentz symmetry in four-dimensional (4D) theory is considered. A source of this symmetry is a group of general linear transformations of four-component Majorana spinors GL(4,M) which is isomorphic to GL(4,R) and is the covering of an extended Lorentz group in a 6D Minkowski space M(3,3) including superluminal and scaling transformations. Physical space-time is assumed to be a 4D pseudo-Riemannian manifold. To connect the extended Lorentz symmetry in the M(3,3) space with the physical space-time, a fiber bundle over the 4D manifold is introduced with M(3,3) as a typical fiber. The action is constructed which is invariant with respect to both general 4D coordinate and local GL(4,M) spinor transformations. The components of the metric on the 6D fiber are expressed in terms of the 4D pseudo-Riemannian metric and two extra complex fields: 4D vector and scalar ones. These extra fields describe in the general case massive particles interacting with an extra U(1) gauge field and weakly interacting with ordinary particles, i.e. possessing properties of invisible (dark) matter.Comment: 24 page

The DAG1 transcription factor negatively regulates the seed-to-seedling transition in Arabidopsis acting on ABA and GA levels

BACKGROUND: In seeds, the transition from dormancy to germination is regulated by abscisic acid (ABA) and gibberellins (GAs), and involves chromatin remodelling. Particularly, the repressive mark H3K27 trimethylation (H3K27me3) has been shown to target many master regulators of this transition. DAG1 (DOF AFFECTING GERMINATION1), is a negative regulator of seed germination in Arabidopsis, and directly represses the GA biosynthetic gene GA3ox1 (gibberellin 3-β-dioxygenase 1). We set to investigate the role of DAG1 in seed dormancy and maturation with respect to epigenetic and hormonal control. RESULTS: We show that DAG1 expression is controlled at the epigenetic level through the H3K27me3 mark during the seed-to-seedling transition, and that DAG1 directly represses also the ABA catabolic gene CYP707A2; consistently, the ABA level is lower while the GA level is higher in dag1 mutant seeds. Furthermore, both DAG1 expression and protein stability are controlled by GAs. CONCLUSIONS: Our results point to DAG1 as a key player in the control of the developmental switch between seed dormancy and germination

Synthesis and Characterization of Nanostructured Oxide Layers on Ti-Nb-Zr-Ta and Ti-Nb-Zr-Fe Biomedical Alloys

Nanoporous/nanotubular complex oxide layers were developed on high-fraction β phase quaternary Ti-Nb-Zr-Ta and Ti-Nb-Zr-Fe promising biomedical alloys with a low elasticity modulus. Surface modification was achieved by electrochemical anodization aimed at the synthesis of the morphology of the nanostructures, which exhibited inner diameters of 15–100 nm. SEM, EDS, XRD, and current evolution analyses were performed for the characterization of the oxide layers. By optimizing the process parameters of electrochemical anodization, complex oxide layers with pore/tube openings of 18–92 nm on Ti-10Nb-10Zr-5Ta, 19–89 nm on Ti-20Nb-20Zr-4Ta, and 17–72 nm on Ti-29.3Nb-13.6Zr-1.9Fe alloys were synthesized using 1 M H3PO4 + 0.5 wt% HF aqueous electrolytes and 0.5 wt% NH4F + 2 wt% H20 + ethylene glycol organic electrolytes

A qualitative continuous model of cellular auxin and brassinosteroid signaling and their crosstalk

Motivation: Hormone pathway interactions are crucial in shaping plant development, such as synergism between the auxin and brassinosteroid pathways in cell elongation. Both hormone pathways have been characterized in detail, revealing several feedback loops. The complexity of this network, combined with a shortage of kinetic data, renders its quantitative analysis virtually impossible at present. Results: As a first step towards overcoming these obstacles, we analyzed the network using a Boolean logic approach to build models of auxin and brassinosteroid signaling, and their interaction. To compare these discrete dynamic models across conditions, we transformed them into qualitative continuous systems, which predict network component states more accurately and can accommodate kinetic data as they become available. To this end, we developed an extension for the SQUAD software, allowing semi-quantitative analysis of network states. Contrasting the developmental output depending on cell type-specific modulators enabled us to identify a most parsimonious model, which explains initially paradoxical mutant phenotypes and revealed a novel physiological feature. Availability: The package SQUADD is freely available via the Bioconductor repository at http://www.bioconductor.org/help/bioc-views/release/bioc/html/SQUADD.html. Contact: [email protected]; [email protected] Supplementary information: Supplementary data are available at Bioinformatics onlin

Modelling state-dependent interference in common cranes

1. Interference is a key component of food competition, but is difficult to measure in natural animal populations. Using data from a long-term study, we show that interference between common cranes Grus grus L., feeding on patches of cereal seeds, reduces intake rates at high competitor densities, and that the strength of interference is unrelated to food abundance. 2. An alternative to measuring interference directly is to predict its strength using behaviour-based models. We test an interference model, originally developed for shorebirds feeding on invertebrate prey, for cranes. We compare the predictions of a rate-maximizing model, in which animals steal food if this increases intake rate, and a state-dependent model, in which they only rate-maximize if their intake rate is below a target value, otherwise they minimize injury risk by not stealing food. State-dependent aggression occurs in cranes. 3. The state-dependent model predicts more accurately the relative aggression rates of cranes of different dominance. However, both models predict accurately the observed strength of interference, that the strength of interference is unrelated to food abundance, at least within the observed range of crane and seed densities, and that cranes of a higher dominance have a higher intake rate than those of lower dominance. 4. This paper shows how state-dependent behaviour can be incorporated into an interference model, and that the model can produce accurate predictions for a system quite different to that for which it was developed.RAS was funded by the Natural Environment Research Council. LMB was partially funded by Ministerio de Ciencia y Tecnología (MCyT) and research grant PB97-1252 of MCyT. Field work was funded by DGICYT project PB87-0389 of the MCyT.Peer reviewe

Evolución de los ácidos grasos en el mesocarpo del níspero (Mespilus germanica. L.) a diferentes estados de maduración

The fatty acid composition of medlar (Mespilus germanica L.) varied significantly among the ripening stages sampled at 157, 172 and 187 DAFs (days after full bloom). Twenty-one different fatty acids were detected in preclimacteric fruit and 17 when the climacteric began. Principal fatty acids, determined in medlar fruit harvested from October (157 and 172 DAFs) to November (187 DAF) were mainly palmitic acid (16:0), linoleic acid (18:2n-6), and a-linolenic acid (18:3n-3). While the content of saturated fatty acids [palmitic acid (16:0) and stearic acid (18:0)] increased, the content of the essential polyunsaturated fatty acids [linoleic acid (18:2n-6) and linolenic acid (18:3n-3)] decreased through ripening, in parallel with pulp darkening. The percentage of linoleic acid and a-linolenic acid in ripe, hard fruits was 60.0 and 13.5 % of dry wt at 157 DAF which decreased throughout ripening, remaining at 28.7 and 5.6 % of dry wt, respectively, in the fully softened and darkened pulp. A marked decreases in the double bond index, percentage of unsaturation and the ratio of unsaturation/saturation were also seen throughout the medlar ripening. The contribution of unsaturated fatty acid to the total fatty acid content decreased markedly as the medlar fruit became progressively softer and darkened.La composición en ácidos grasos del níspero (Mespilus germanica L.) varió significativamente entre los estados de maduración muestreados a los 157, 172 y 187 DAFs (días después de la floración). Veinte y un ácidos grasos diferentes fueron detectados en el fruto preclimatérico y 17 cuando comenzó el climaterio. Los ácidos grasos principales encontrados en nísperos, recolectados desde Octubre (157 y 172 DAFs) hasta Noviembre (187 DAF), fueron principalmente ácido palmítico (16:0), ácido linoléico (18:2n-6), y ácido a-linolénico (18:3n-3). En tanto que el contenido en ácidos grasos saturados (ácido palmítico (16:0) y ácido esteárico (18:0)) aumentó, el contenido en ácidos grasos esenciales (ácido linoleico (18:2n-6) y ácido linolénico (18:3n-6)) disminuyó durante la maduración, en paralelo con el oscurecimiento de la pulpa. El porcentaje de ácido linoleico y de ácido a-linolénico en frutos maduros sin reblandecer fue de 60.0 y 13.5 % del peso seco a 157 DAF, disminuyendo durante la maduración, y permaneciendo a 28.7 y 56 % del peso seco, respectivamente, en la pulpa completamente blanda y oscura. También se observó durante la maduración del níspero una marcada disminución en el número de dobles enlaces, en el tanto por ciento de instauración y en la relación instauración / saturación. La contribución de los ácidos grasos insaturados al contenido de ácidos grasos totales disminuyó marcadamente cuando el níspero comenzó progresivamente a reblandecerse y oscurecerse

Application of mineralogical, petrological and geochemical tools for evaluating the palaeohdrogeological evolution of the PADAMOT study sites

The role of Work Package (WP) 2 of the PADAMOT project – ‘Palaeohydrogeological Data Measurements’ - has been to study late-stage fracture mineral and water samples from groundwater systems in Spain, Sweden, United Kingdom and the Czech Republic, with the aim of understanding the recent palaeohydrogeological evolution of these groundwater systems. In particular, the project sought to develop and evaluate methods for obtaining information about past groundwater evolution during the Quaternary (about the last 2 million years) by examining how the late-stage mineralization might record mineralogical, petrographical and geochemical evidence of how the groundwater system may have responded to past geological and climatological changes. Fracture-flow groundwater systems at six European sites were studied: • Melechov Hill, in the Bohemian Massif of the Czech Republic: a shallow (0-100 m) dilute groundwater flow system within the near-surface weathering zone in fractured granitic rocks; • Cloud Hill, in the English Midlands: a (~100 m) shallow dilute groundwater flow system in fractured and dolomitized Carboniferous limestone; • Los Ratones, in southwest Spain: an intermediate depth (0-500 m) dilute groundwater flow system in fractured granitic rocks; • Laxemar, in southeast Sweden: a deep (0-1000 m) groundwater flow system in fractured granitic rocks. This is a complex groundwater system with potential recharge and flushing by glacial, marine, lacustrine and freshwater during the Quaternary; • Sellafield, northwest England: a deep (0-2000 m) groundwater flow system in fractured Ordovician low-grade metamorphosed volcaniclastic rocks and discontinuous Carboniferous Limestone, overlain by a Permo-Triassic sedimentary sequence with fracture and matrix porosity. This is a complex coastal groundwater system with deep hypersaline sedimentary basinal brines, and deep saline groundwaters in crystalline basement rocks, overlain by a shallow freshwater aquifer system. The site was glaciated several times during the Quaternary and may have been affected by recharge from glacial meltwater; • Dounreay, northeast Scotland: a deep (0-1400 m) groundwater flow system in fractured Precambrian crystalline basement overlain by fractured Devonian sedimentary rocks. This is within the coastal discharge area of a complex groundwater system, comprising deep saline groundwater hosted in crystalline basement, overlain by a fracture-controlled freshwater sedimentary aquifer system. Like Sellafield, this area experienced glaciation and may potentially record the impact of glacial meltwater recharge. In addition, a study has been made of two Quaternary sedimentary sequences in Andalusia in southeastern Spain to provide a basis of estimating the palaeoclimatic history of the region that could be used in any reconstruction of the palaeoclimatic history at the Los Ratones site: • The Cúllar-Baza lacustrine sequence records information about precipitation and palaeotemperature regimes, derived largely from the analysis of the stable isotope (δ18O and δ13C) signatures from biogenic calcite (ostracod shells). • The Padul Peat Bog sequence provided information on past vegetation cover and palaeogroundwater inputs based on the study of fossil pollen and biomarkers as proxies for past climate change. Following on from the earlier EC 4th Framework EQUIP project, the focus of the PADAMOT studies has been on calcite mineralization. Calcite has been identified as a late stage mineral, closely associated with hydraulically-conductive fractures in the present-day groundwater systems at the Äspö-Laxemar, Sellafield, Dounreay and Cloud Hill sites. At Los Ratones and Melechov sites late-stage mineralization is either absent or extremely scarce, and both the quantity and fine crystal size of any late-stage fracture mineralization relevant to Quaternary palaeohydrogeological investigations is difficult to work with. The results from the material investigated during the PADAMOT studies indicate that the fracture fillings at these sites are related to hydrothermal activity, and so do not have direct relevance as Quaternary indicators. Neoformed calcite has not been found at these two sites at the present depth of the investigations. Furthermore, the HCO3 - concentration in all the Los Ratones groundwaters is mainly controlled by complex carbonate dissolution. The carbonate mineral saturation indices do not indicate precipitation conditions, and this is consistent with the fact that neoformed calcite, ankerite or dolomite have not been observed petrographically