Fields

We construct relativistic-invariant spinning-particle Lagrangian without auxiliary variables. Spin is considered as a composed quantity constructed on the base of non-Grassmann vector-like variable. The variational problem guarantees both fixed value of spin and Frenkel condition on spin-tensor. Taking into account the Frenkel condition, we obtain, inevitably, relativistic corrections to the algebra of position variables: their classical brackets became noncommutative, with the "parameter of non-commutativity" proportional to the spin-tensor. This leads to a number of interesting consequences in quantum theory. We construct the relativistic quantum mechanics in canonical formalism (in physical-time parametrization) and in covariant formalism (in arbitrary parametrization). We show how state-vectors and operators of covariant formulation can be used to compute mean values of physical operators of position and spin. This proves relativistic covariance of canonical formalism....

Through the publication of her bestseller Uncle Tom’s Cabin, Harriet Beecher Stowe became one of the most internationally famous and important authors in nineteenth-century America. Today, her reputation is more complex, and Uncle Tom’s Cabin has been debated and analyzed in many different ways. This book provides a summary of Stowe’s life and her long career as a professional author, as well as an overview of her writings in several different genres. Synthesizing scholarship from a range of perspectives, the book positions Stowe’s work within the larger framework of nineteenth-century culture and attitudes about race, slavery and the role of women in society. Sarah Robbins also offers reading suggestions for further study. This introduction provides students of Stowe with a richly informed and accessible introduction to this fascinating author.

An ultra-compact Marx-type high-voltage generator includes individual high-performance components that are closely coupled and integrated into an extremely compact assembly. In one embodiment, a repetitively-switched, ultra-compact Marx generator includes low-profile, annular-shaped, high-voltage, ceramic capacitors with contoured edges and coplanar extended electrodes used for primary energy storage; low-profile, low-inductance, high-voltage, pressurized gas switches with compact gas envelopes suitably designed to be integrated with the annular capacitors; feed-forward, high-voltage, ceramic capacitors attached across successive switch-capacitor-switch stages to couple the necessary energy forward to sufficiently overvoltage the spark gap of the next in-line switch; optimally shaped electrodes and insulator surfaces to reduce electric field stresses in the weakest regions where dissimilar materials meet, and to spread the fields more evenly throughout the dielectric materials, allo...

Thirty-one clones of sweetpotatoes collected from some parts of Zimbabwe were used as inoculum sources to mechanically inoculate 13 experimental hosts: Chenopodium amaranticolor, C. quinoa, Cucumis sativus, Datura stramoniumitalic, Gomphrena globosa, Ipomoea purpurea, I. quamoclit, I. rubrocorulea, Nicotiana benthamiana, N. clevelandii, N. glutinosa, N. rustica, and N. tabacum. Systemic vein clearing was observed in N. benthamiana inoculated with buffered sap from nine clones. Purification of the vein clearing inducing agent from one of the sweetpotato clones gave yields ranging from 2 to 17 mg/kg and the A260nm/A280nm was around 1.2. Electron microscopy revealed flexuous filamentous particles with a modal length of 830 nm. Protein analysis of purified virus preparations by sodium dodecyl sulfate polyacrylamide gel electrophoresis revealed a major protein band of 40 kDa, and this was assumed to be the viral coat protein. Minor protein bands of 27, 37, and 46 kDa were also observed. ...

Arc interruptions and, therefore, oscillation in the amount of energy and molten wire delivered to the plate have been observed during tandem pulsed gas metal arc welding (GMAW). It appears that these instabilities are related to the magnetic interaction between the arcs. In order to clarify the possible mechanisms involved, this paper tries to mimic the tandem GMAW arc interruptions. External magnetic fields were dynamically applied to GTAW arcs in constant current mode to verify their resistance to extinction as a function of current level and direction of deflection. High-speed filming was carried out as an additional tool to understand the extinction mechanism. The influence of the welding current level on the arc resistance to extinction was established: The higher the welding current, the more the arc resists to the extinction. The arc deflection direction has minor effect, but arcs deflected backward have more resistance to extinction.

Due to a malaria outbreak in 2003, a large-scale mosquito larval distribution study was carried out in Sukabumi District, West Java. Mosquito larvae found in sampled habitats were collected and reared to adults for identification. Sukabumi District is the province of West Java's ...

The paper introduces, analyzes and evaluates the outcomes of a design experiment that took place at the Aristotle University of Thessaloniki in the form of an intensive workshop on parametric urban design. The strategies and methods adopted defined a field for design experimentation as a response to the broader disciplinary discourse related to the use of advanced digital tools, their potentialities in dealing with urban form and their role in architectural education. The workshop’s operative processes and the results obtained serve as a paradigm for an alternative urban design approach. The analysis and the evaluation of this specific approach give rise to further questions and define the goals and anticipations of related future investigations.

The gauge-dependence of the one loop Coleman-Weinberg effective potential in scalar electrodynamics is resolved using a gauge-free approach not requiring any gauge-fixing of quantum fluctuations of the photon degrees of freedom. This leads to a unique dynamical ratio at one loop of the Higgs mass to the photon mass. We compare our approach and results with those obtained in geometric framework of DeWitt and Vilkovisky, which maintains invariance under field redefinitions as well as invariance under background gauge transformations, but {\it requires}, in contrast to our approach, gauge fixing of {\it fluctuating} photon fields. We also discuss possible modifications of the Coleman-Weinberg potential if we adapt the DeWitt-Vilkovisky method to our gauge-free approach for scalar QED.

1Abandoned agricultural (AA) fields are often invaded by exotic plants. This observation has been difficult to explain because agricultural practices change nearly every aspect of an ecosystem. Restoring native plants to AA fields is likely to require a prioritized understanding of the many mechanisms through which agriculture encourages exotic and discourages native plant growth.2Using 660 experimental plots in three sites in Methow Valley, Washington, USA, we determined the relative role of neighbour removal, propagule addition, plant–soil feedback, soil disturbance and fungal restriction to explain why exotics cover 38% of the ground in AA fields and 3% of the ground in non-agricultural (NA) fields.3After three growing seasons, neighbour removal improved exotic growth from 3% to 11% cover in NA fields but had no effect in AA fields. Propagule addition did not increase exotic growth above natural recruitment. Differences in soil history, a proxy for plant–soil feedback, explained an increase in exotic growth from 9% in NA fields to 39% in AA fields. Soil disturbance improved exotic growth from 9% to 16% cover in NA fields but had no effect in AA fields. Fungicide reduced exotic growth from 39% to 28% cover in AA soils but had no effect on exotic growth in NA soils. Native plant growth never differed by more than 5% cover among treatments.4Soil carbon, nitrogen (organic, inorganic and mineralization), phosphorus concentrations and fungal biomass were better associated with plant type (exotic or native) than agricultural history, suggesting that exotics facilitated their own growth by maintaining small beneficial fungal populations and fast nutrient cycling rates.5 Synthesis and application. Soil history was more important than neighbour removal in determining exotic and native plant distributions. Where exotics rely on plant–soil feedback or legacies of agricultural disturbance, native plant restoration may require soil-based management. In these cases, changing mycorrhizal fungal abundance, increasing soil pathogen loading and slowing nutrient cycling rates may help restore native plants to invaded fields.Abandoned agricultural (AA) fields are often invaded by exotic plants. This observation has been difficult to explain because agricultural practices change nearly every aspect of an ecosystem. Restoring native plants to AA fields is likely to require a prioritized understanding of the many mechanisms through which agriculture encourages exotic and discourages native plant growth.Using 660 experimental plots in three sites in Methow Valley, Washington, USA, we determined the relative role of neighbour removal, propagule addition, plant–soil feedback, soil disturbance and fungal restriction to explain why exotics cover 38% of the ground in AA fields and 3% of the ground in non-agricultural (NA) fields.After three growing seasons, neighbour removal improved exotic growth from 3% to 11% cover in NA fields but had no effect in AA fields. Propagule addition did not increase exotic growth above natural recruitment. Differences in soil history, a proxy for plant–soil feedback, explained an increase in exotic growth from 9% in NA fields to 39% in AA fields. Soil disturbance improved exotic growth from 9% to 16% cover in NA fields but had no effect in AA fields. Fungicide reduced exotic growth from 39% to 28% cover in AA soils but had no effect on exotic growth in NA soils. Native plant growth never differed by more than 5% cover among treatments.Soil carbon, nitrogen (organic, inorganic and mineralization), phosphorus concentrations and fungal biomass were better associated with plant type (exotic or native) than agricultural history, suggesting that exotics facilitated their own growth by maintaining small beneficial fungal populations and fast nutrient cycling rates. Synthesis and application. Soil history was more important than neighbour removal in determining exotic and native plant distributions. Where exotics rely on plant–soil feedback or legacies of agricultural disturbance, native plant restoration may require soil-based management. In these cases, changing mycorrhizal fungal abundance, increasing soil pathogen loading and slowing nutrient cycling rates may help restore native plants to invaded fields.

We survey some results on the structure of the groups which are definable in theories of fields involved in the applications of model theory to Diophantine geometry. We focus more particularly on separably closed fields of finite degree of imperfection.

Bacillus thuringiensis (Bt) isolates were present on the phylloplanes of chickpea (Cicer arietinum), pigeon pea (Cajanus cajan), pea (Pisum sativum) and mung bean (Vigna radiata). Bt index (ratio of the number of Bt colonies to the total number of spore-forming colonies per g of leaves) differed significantly among these plants, with the highest (0.20) in the chickpea phylloplane, followed by pigeon pea (0.17). Bt population of the chickpea phylloplane varied with plant age, being maximal in 45-day-old plants. Diversity was observed among Bt isolates for growth (up to 10-fold difference), antibiotic resistance, PCR product profile and toxicity to Helicoverpa armigera. Two isolates with high activity towards H. armigera were found.