Cosmological Inflation with orbifold moduli as inflatons

Cosmological inflation is studied in the case where the inflaton is the overall modulus $T$ for an orbifold. General forms of the (non-perturbative) superpotential are considered to ensure that $G=K+{\rm ln}|W|^2$ is modular invariant. We find generically that these models do not produce a potential flat enough for slow roll to a supersymmetric minimum, although we do find a model which produces up to 20 e-folds of inflation to a non-supersymmetric minimum.Comment: LaTeX file, 16 pages including 5 figures, v3 is the published versio

On Interaction Classification

Further classification is made of Lindquist's dichotomy of inter action effects. The extension hopefully reduces errors of inter pretation and provides a simple, accurate means of summarizing in teractions obtained.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/67338/2/10.1177_001316448004000405.pd

Desulfurizing Coal with Alkaline Solutions Containing Dissolved Oxygen

The extraction of pyritic sulfur from coal by leaching the comminuted material with hot aqueous solutions containing dissolved oxygen has been demonstrated in numerous laboratory experiments (1-6). Although acidic solutions have generally been used for such experiments, basic solutions appear to offer several important advantages. Thus Majima and Peters (7) showed that the rate of extraction of sulfur from relatively pure pyrite is much greater in basic solutions containing dissolved oxygen than in neutral solutions. Moreover it has been shown recently that basic solutions containing ammonium hydroxide and oxygen can extract a significant portion of the organic sulfur as well as most of the inorganic sulfur from coal at relatively moderate temperatures (e.g., 130°C) (4,5) whereas higher temperatures (150°-200°C) seem to be required with acidic solutions to remove organic sulfur (6). Furthermore some types of basic solutions are much less corrosive towards the common materials of construction than acidic solutions.Reprinted (adapted) with permission from Coal Desulfurization Chapter 15, pp 182–197 DOI: 10.1021/bk-1977-0064.ch015. Copyright 1977 American Chemical Society.</p

Using Scalars to Probe Theories of Low Scale Quantum Gravity

Arkani-Hamed, Dimopoulos and Dvali have recently suggested that gravity may become strong at energies near 1 TeV which would remove the hierarchy problem. Such a scenario can be tested at present and future colliders since the exchange of towers of Kaluza-Klein gravitons leads to a set of new dimension-8 operators that can play important phenomenological roles. In this paper we examine how the production of pairs of scalars at $e^+e^-$, $\gamma \gamma$ and hadron colliders can be used to further probe the effects of graviton tower exchange. In particular we examine the tree-level production of pairs of identical Higgs fields which occurs only at the loop level in both the Standard Model and its extension to the Minimal Supersymmetric Standard Model. Cross sections for such processes are found to be potentially large at the LHC and the next generation of linear colliders. For the $\gamma\gamma$ case the role of polarization in improving sensitivity to graviton exchange is emphasized.Comment: 32 pages, 12 figures, latex, remarks added to tex

Microstructural and Rheological Transitions in Bacterial Biofilms

Abstract Biofilms are aggregated bacterial communities structured within an extracellular matrix (ECM). ECM controls biofilm architecture and confers mechanical resistance against shear forces. From a physical perspective, biofilms can be described as colloidal gels, where bacterial cells are analogous to colloidal particles distributed in the polymeric ECM. However, the influence of the ECM in altering the cellular packing fraction (ϕ) and the resulting viscoelastic behavior of biofilm remains unexplored. Using biofilms of Pantoea sp. (WT) and its mutant (ΔUDP), the correlation between biofilm structure and its viscoelastic response is investigated. Experiments show that the reduction of exopolysaccharide production in ΔUDP biofilms corresponds with a seven‐fold increase in ϕ, resulting in a colloidal glass‐like structure. Consequently, the rheological signatures become altered, with the WT behaving like a weak gel, whilst the ΔUDP displayed a glass‐like rheological signature. By co‐culturing the two strains, biofilm ϕ is modulated which allows us to explore the structural changes and capture a change in viscoelastic response from a weak to a strong gel, and to a colloidal glass‐like state. The results reveal the role of exopolysaccharide in mediating a structural transition in biofilms and demonstrate a correlation between biofilm structure and viscoelastic response

Increased uptake of putrescine in the Rhizosphere inhibits competitive root colonization by Pseudomonas fluoresecens strain WCS365

Microbial Biotechnolog

Drawings as representations of children's conceptions

Drawings are often used to get an idea of children's conceptions. Doing so takes for granted an unambiguous relation between conceptions and their representations in drawings. This study was undertaken to gain knowledge of the relation between children's conceptions and their representation of these conceptions in drawings. A theory of contextualization was the basis for finding out how children related their contextualization of conceptions in conceptual frameworks to their contextualization of drawings in pictorial convention. Eighteen children were interviewed in a semi-structured method while they were drawing the Earth. Audio-recorded interviews, drawings and notes were analysed to find the cognitive and cultural intentions behind the drawings. Also, even children who demonstrated alternative conceptions of the Earth in the interviews still followed cultural conventions in their drawings. Thus, these alternative conceptions could not be deduced from the drawings. The results indicate that children's drawings can be used to grasp children's conceptions only by considering the meaning the children themselves give to their own drawings

Deep Inelastic Scattering from off-Shell Nucleons

We derive the general structure of the hadronic tensor required to describe deep-inelastic scattering from an off-shell nucleon within a covariant formalism. Of the large number of possible off-shell structure functions we find that only three contribute in the Bjorken limit. In our approach the usual ambiguities encountered when discussing problems related to off-shellness in deep-inelastic scattering are not present. The formulation therefore provides a clear framework within which one can discuss the various approximations and assumptions which have been used in earlier work. As examples, we investigate scattering from the deuteron, nuclear matter and dressed nucleons. The results of the full calculation are compared with those where various aspects of the off-shell structure are neglected, as well as with those of the convolution model.Comment: 36 pages RevTeX, 9 figures (available upon request), ADP-93-210/T128, PSI-PR-93-13, accepted for publication in Physical Review

Introduction of the phzH gene of Pseudomonas chlororaphis PCL1391 extends the range of biocontrol ability of Phenazine-1-Carboxylic Acid-Producing pseudomonas spp. strains

Microbial Biotechnolog