Non-uniform Braneworld Stars: an Exact Solution

The first exact interior solution to Einstein's field equations for a static and non-uniform braneworld star with local and non-local bulk terms is presented. It is shown that the bulk Weyl scalar ${\cal U}(r)$ is always negative inside the stellar distribution, in consequence it reduces both the effective density and the effective pressure. It is found that the anisotropy generated by bulk gravity effect has an acceptable physical behaviour inside the distribution. Using a Reissner-N\"{o}rdstrom-like exterior solution, the effects of bulk gravity on pressure and density are found through matching conditions.Comment: 22 pages, 3 figures, version to be published in International Journal of Modern Physics D (IJMPD

On the Substitution of Identicals in Counterfactual Reasoning

It is widely held that counterfactuals, unlike attitude ascriptions, preserve the referential transparency of their constituents, i.e., that counterfactuals validate the substitution of identicals when their constituents do. The only putative counterexamples in the literature come from counterpossibles, i.e., counterfactuals with impossible antecedents. Advocates of counterpossibilism, i.e., the view that counterpossibles are not all vacuous, argue that counterpossibles can generate referential opacity. But in order to explain why most substitution inferences into counterfactuals seem valid, counterpossibilists also often maintain that counterfactuals with possible antecedents are transparency‐preserving. I argue that if counterpossibles can generate opacity, then so can ordinary counterfactuals with possible antecedents. Utilizing an analogy between counterfactuals and attitude ascriptions, I provide a counterpossibilist‐friendly explanation for the apparent validity of substitution inferences into counterfactuals. I conclude by suggesting that the debate over counterpossibles is closely tied to questions concerning the extent to which counterfactuals are more like attitude ascriptions and epistemic operators than previously recognized

An electron hole doping and soft x-ray spectroscopy study on La1-xSrxFe0.75Ni0.25O3-{\delta}

The conductivity of the electron hole and polaron conductor La1-xSrxFe0.75Ni0.25O3-{\delta}, a potential cathode material for intermediate temperature solid oxide fuel cells, was studied for 0 <x < 1 and for temperatures 300 K <T < 1250 K. In LaSrFe-oxide, an ABO3 type perovskite, A-site substitu-tion of the trivalent La3+ by the divalent Sr2+ causes oxidation of Fe3+ towards Fe4+, which forms conducting electron holes. Here we have in addition a B-site substitution by Ni. The compound for x = 0.5 is identified as the one with the highest conductivity ({\sigma} ~ 678 S/cm) and lowest activation energy for polaron conductivity (Ep = 39 meV). The evolution of the electronic structure was monitored by soft x-ray Fe and oxygen K-edge spectroscopy. Homogeneous trend for the oxida-tion state of the Fe was observed. The variation of the ambient temperature conductivity and activation energy with relative Sr content (x) shows a correlation with the ratio of (eg/eg+t2g) in Fe L3 edge up to x=0.5. The hole doping process is reflected by an almost linear trend by the variation of the pre-peaks of the oxygen K-edge soft x-ray absorption spectra

Biological Fixation of N2 in Mono and Polyspecific Legume Pasture in the Humid Mediterranean Zone of Chile

del Pozo, A (del Pozo, Alejandro). Univ Talca, Fac Ciencias Agr, Talca, ChileDespite annual legume pasture are of great importance for dryland agricultural systems in Mediterranean environments, there are few studies of N-2 biological fixation (NBF) reported in Chile. In this study the NBF of four annual legume species: subterranean clover (Trifolium subterraneum L.), yellow serradella (Ornithopus compressus L.), arrow-leaf clover (T. vesiculosum L.), and crimson clover (T. incarnatum L.) (Experiment 1), as well as seven mixtures of these species (Experiment 2) were assessed. The NBF was measured by the N-15 natural abundance technique. The objective was to determine NBF in the legume species and in distinct mixtures used. The study was carried out in an Andisol of the Andean Precordillera located in the humid Mediterranean zone of Chile. Pasture was evaluated for biomass; and total N and natural abundance of N-15 were analyzed in plant material samples. In Experiment 1 (monospecific legume species pasture), N derived from fixation ranged between 43 and 147 kg N ha(-1) and where T. vesiculosum and T. subterraneum presented statistical differences (P <= 0.05) in connection with the other species. In the legume mixtures (Experiment 2), N derived by fixation varied between 97 and 214 kg N ha(-1) where the 50-50 mixtures (T. subterraneum and O. compressus, or T. subterraneum and T. vesiculosum, respectively) had the highest N fixation. Fixed N ranged between 12 and 25 kg N t(-1) DM, showing significant differences among mono and polyspecific legume species

Managing Vegetation In Grassland Habitats To Enhance Livestock Or Wildlife Objectives

Sustainably stewarding grassland systems involves applying various practices to manipulate forage interactions with other plants, the environment, and grazing animals to meet resource manager objectives. These interactions can result in invasion or encroachment and increased abundance of weeds which hinder attainment of management objectives. Weeds influence the structure and function of pasture ecosystems whether forages are grown in improved pastures, rangeland, or grassland communities. They degrade pasture quality and reduce livestock performance by interfering with forage establishment, yield, and quality by competing for resources. Weeds reduce the feed value of forage, decrease pasture carrying capacity, and can be toxic or unpalatable to livestock. Managing weeds requires use of vegetation management tools that favor desirable forages. Herbicides can be a catalyst that expedite grassland renovation, improve the forage resource, and increase carrying capacity. Corteva Agriscience has a variety of herbicide products that provide superior control of herbaceous and woody weeds, while maintaining the desirable vegetation. These herbicides were designed and developed specifically for selective broadleaf weed control in rangeland, pastures, rights-of-way, non-cropland, and natural areas. Active ingredients historically used include aminopyralid, triclopyr, fluroxypyr, clopyralid, and picloram. Rinskor™ active and Arylex™ active are new herbicide active ingredients from Corteva Agriscience™ and are members of a unique synthetic auxin chemotype, the arylpicolinates (HRAC group O / WSSA group 4). Members of the arylpicolinate family demonstrate novel and differentiated characteristics in terms of use rate, spectrum, weed symptoms, environmental fate, and molecular interaction as compared to other auxin chemotypes. When applied as a stand-alone treatment or in various mixes these products are safe to desirable grass species and control key herbaceous and woody weeds in the genera Ambrosia, Acacia, Carduus, Centaurea, Cirsium, Mimosa, Prosopis, Ranunculus, Rumex, Sida, Solanum, Taraxacum, and more

Yttrium and Hydrogen Superstructure and Correlation of Lattice Expansion and Proton Conductivity in the BaZr0.9Y0.1O2.95 Proton Conductor

Bragg reflections in Y-resonant x-ray diffractograms of BaZr0.9Y0.1O2.95 (BZY10) reveal that Y is organized in a superstructure. Comparison with neutron diffraction superstructure reflections in protonated/deuterated BZY10 suggests that both superstructures are linked, and that protons move in the landscape imposed by the Y. The thermal lattice expansion decreases abruptly for protonated BZY10 at T≥648±20 K, coinciding with the onset of lateral proton diffusion and suggesting a correlation of structural changes and proton conductivity. The chemical shift in the Y L1-shell x-ray absorption spectra reveals a reduction from Y3+ toward Y2+ upon protonation

On the validity of the 5-dimensional Birkhoff theorem: The tale of an exceptional case

The 5-dimensional (5d) Birkhoff theorem gives the class of 5d vacuum space-times containing spatial hypersurfaces with cosmological symmetries. This theorem is violated by the 5d vacuum Gergely-Maartens (GM) space-time, which is not a representant of the above class, but contains the static Einstein brane as embedded hypersurface. We prove that the 5d Birkhoff theorem is still satisfied in a weaker sense: the GM space-time is related to the degenerated horizon metric of certain black-hole space-times of the allowed class. This result resembles the connection between the Bertotti-Robinson space-time and the horizon region of the extremal Reissner-Nordstrom space-time in general relativity.Comment: 13 pages; v2: title amended, to be published in Classical and Quantum Gravit

Revisi\uf3n - Serradela amarilla ( Ornithopus compressus ) y serradela rosada (o. sativus): dos nuevas especies de leguminosas forrajeras anuales para la zona Mediterr\ue1nea de Chile

Yellow serradella ( Ornithopus compressus L.) and pink serradella ( Ornithopus sativus Brot.) are two new annual foragelegume species for infertile, acidic, and light texture soils, in dryland areas of the Mediterranean zone of Chile. Seven cultivars of yellow serradella and one cultivar of pink serradella, developed bytheCenter for Legumes in Mediterranean Agriculture (CLIMA),Australia, were characterized. O. compressus presented a high to medium hardseededness (53 to 100% at the beginning of the second growth season), while O. sativus presented a very low hardseededness (4%). A variable range of precocity was detected (108 to 143 days to flowering). The growth habit is semi-erect to erect, flowers are yellow in O. compressus and pink in O. sativus. The dry matter and seed production is comparable, and in some years superior, to that of species of traditional use in these areas, like subterranean clover ( Trifolium subterraneum L.) and hualputra ( Medicago polymorpha L.), standing out serradellas especially for their high production in infertile soils of the interior dry lands of Cauquenes, in the third year of evaluation (2200 to 4200 kg DM ha-1, 650 to 1440 kg seeds ha-1) The available phenological and productive data allow to think that the development of pastures based on serradellas, could mean an important contribution to the improvement of the pastoral production of extensive marginal areas of the non-irrigated Mediterranean land of Chile.La serradela amarilla ( Ornithopus compressus L.) y la serradela rosada ( Ornithopus sativus Brot.) son dos nuevas especies de leguminosas forrajeras anuales para suelos \ue1cidos inf\ue9rtiles, de texturas livianas, en zonas de secano mediterr\ue1neo de Chile. Se caracterizaron siete cultivares de serradela amarilla y uno de serradela rosada, desarrollados por el Centre for Legumes in Mediterranean Agriculture (CLIMA) de Australia. O. compressus present\uf3 una dureza seminal media a alta (53 a 100% al inicio de la segunda temporada de crecimiento), mientras que O. sativus present\uf3 una dureza seminal muy baja (4%). Se detect\uf3 un rango de precocidad variable (entre 108 y 143 d\uedas a floraci\uf3n). El h\ue1bito de crecimiento fue semi-erecto a erecto, flores de color amarillo en el caso de O. compressus y rosadas en el caso de O. sativus. La producci\uf3n de materia seca y de semillas fue comparable, y en algunos a\uf1os superior, al de las especies de uso tradicional en estas zonas, como tr\ue9bol subterr\ue1neo ( Trifolium subterraneum L.) y hualputra ( Medicago polymorpha L.), destac\ue1ndose las serradelas por su alta producci\uf3n, especialmente en suelos inf\ue9rtiles del secano interior de Cauquenes, al tercer a\uf1o de evaluaci\uf3n (2200-4200 kg MS ha-1, 650-1440 kg semilla ha-1). Los antecedentes de fenolog\ueda y comportamiento productivo permiten vislumbrar que el desarrollo de praderas en base a serradelas, podr\ueda significar un importante aporte al mejoramiento de la producci\uf3n pastoral de extensas \ue1reas marginales del secano mediterr\ue1neo de Chile