Classical Symmetries of Some Two-Dimensional Models Coupled to Gravity

This paper is a sequel to one in which we examined the affine symmetry algebras of arbitrary classical principal chiral models and symmetric space models in two dimensions. It examines the extension of those results in the presence of gravity. The main result is that even though the symmetry transformations of the fields depend on the gravitational background, the symmetry algebras of these classical theories are completely unchanged by the presence of arbitrary gravitational backgrounds. On the other hand, we are unable to generalize the Virasoro symmetries of the flat-space theories to theories with gravity.Comment: 22 pages, late

The ambiguity of mutuality:Discourse and power in corporate value regimes

Corporate values offer a means for consecrating alternative regimes of worth within businesses, explicitly orienting firms around more than the pursuit of profits. This paper examines how corporate values come to be constructed and diffused as a framework for interpretation and action through analysis of Food Co.’s flagship principle: ‘mutuality’. Tracing the deployment of mutuality through Food Co.’s internal processes (within the embodied practice and narratives of employees) and external relationships (within Food Co.’s bottom of the pyramid project in Kenya), the paper illustrates how the ambiguity of mutuality forms a strategic resource for the company by (i) sheltering multiple meanings and interpretations, thus enabling resonance among different situations and subject positions; (ii) allowing for syncretism between seemingly opposing and categorically different forms; and (iii) generating a space for negotiation and dealing with uncertainty. Employing these three themes of ambiguity as an organizing frame for our discussion, we highlight how the ambiguity of corporate values absorbs the contradictions emblematic of the ‘heterarchical firm’ (Stark 2000), while obscuring the obligations and expectations the concept entails as it moves beyond Food Co. to outsourced ‘entrepreneurs’ in Kenya. Language generates the appearance of equivalence and benevolence while seeking new spaces for accumulation and legitimizing the incorporation of labor on precarious terms

Infinite-Dimensional Symmetries of Two-Dimensional Coset Models

It has long been appreciated that the toroidal reduction of any gravity or supergravity to two dimensions gives rise to a scalar coset theory exhibiting an infinite-dimensional global symmetry. This symmetry is an extension of the finite-dimensional symmetry G in three dimensions, after performing a further circle reduction. There has not been universal agreement as to exactly what the extended symmetry algebra is, with different arguments seemingly concluding either that it is $\hat G$, the affine Kac-Moody extension of G, or else a subalgebra thereof. Exceptional in the literature for its explicit and transparent exposition is the extremely lucid discussion by Schwarz, which we take as our starting point for studying the simpler situation of two-dimensional flat-space sigma models, which nonetheless capture all the essential details. We arrive at the conclusion that the full symmetry is described by the Kac-Moody algebra G, although truncations to subalgebras, such as the one obtained by Schwarz, can be considered too. We then consider the explicit example of the SL(2,R)/O(2) coset, and relate Schwarz's approach to an earlier discussion that goes back to the work of Geroch.Comment: Typos corrected, some reorganisation; 36 page

Genetic Analyses and Annotations of Two Newly Discovered C1 Mycobacteriophages

Poster presentation abstract

A streamlined method for systematic, high resolution in situ analysis of mRNA distribution in plants

BACKGROUND: In situ hybridisation can provide cellular, and in some cases sub-cellular, resolution of mRNA levels within multicellular organisms and is widely used to provide spatial and temporal information on gene expression. However, standard protocols are complex and laborious to implement, restricting analysis to one or a few genes at any one time. Whole-mount and reverse transcriptase-PCR (RT-PCR) based protocols increase throughput, but can compromise both specificity and resolution. With the advent of genome-wide analysis of gene expression, there is an urgent need to develop high-throughput in situ methods that also provide high resolution. RESULTS: Here we describe the development of a method for performing high-throughput in situ hybridisations that retains both the high resolution and the specificity of the best manual versions. This refined semi-automated protocol has the potential for determining the spatial and temporal expression patterns of hundreds of genes in parallel on a variety of tissues. We show how tissue sections can be organized on microscope slides in a manner that allows the screening of multiple probes on each slide. Slide handling, hybridisation and processing steps have been streamlined providing a capacity of at least 200 probes per week (depending on the tissue type). The technique can be applied easily to different species and tissue types, and we illustrate this with wheat seed and Arabidopsis floral meristems, siliques and seedlings. CONCLUSION: The approach has the high specificity and high resolution of previous in situ methods while allowing for the analysis of several genes expression patterns in parallel. This method has the potential to provide an analysis of gene expression patterns at the genome level

DUALITY SYMMETRY GROUP OF TWO DIMENSIONAL HETEROTIC STRING THEORY

The equations of motion of the massless sector of the two dimensional string theory, obtained by compactifying the heterotic string theory on an eight dimensional torus, is known to have an affine o(8,24) symmetry algebra generating an O(8,24) loop group. In this paper we study how various known discrete S- and T- duality symmetries of the theory are embedded in this loop group. This allows us to identify the generators of the discrete duality symmetry group of the two dimensional string theory.Comment: LaTeX, 30 page

Classical Symmetries of Some Two-Dimensional Models

It is well-known that principal chiral models and symmetric space models in two-dimensional Minkowski space have an infinite-dimensional algebra of hidden symmetries. Because of the relevance of symmetric space models to duality symmetries in string theory, the hidden symmetries of these models are explored in some detail. The string theory application requires including coupling to gravity, supersymmetrization, and quantum effects. However, as a first step, this paper only considers classical bosonic theories in flat space-time. Even though the algebra of hidden symmetries of principal chiral models is confirmed to include a Kac--Moody algebra (or a current algebra on a circle), it is argued that a better interpretation is provided by a doubled current algebra on a semi-circle (or line segment). Neither the circle nor the semi-circle bears any apparent relationship to the physical space. For symmetric space models the line segment viewpoint is shown to be essential, and special boundary conditions need to be imposed at the ends. The algebra of hidden symmetries also includes Virasoro-like generators. For both principal chiral models and symmetric space models, the hidden symmetry stress tensor is singular at the ends of the line segment.Comment: 51 pages, minor corrections and added reference

Colliding Wave Solutions, Duality, and Diagonal Embedding of General Relativity in Two-Dimensional Heterotic String Theory

The non-linear sigma model of the dimensionally reduced Einstein (-Maxwell) theory is diagonally embedded into that of the two-dimensional heterotic string theory. Consequently, the embedded string backgrounds satisfy the (electro-magnetic) Ernst equation. In the pure Einstein theory, the Matzner-Misner SL(2,{\bf R}) transformation can be viewed as a change of conformal structure of the compactified flat two-torus, and in particular its integral subgroup SL(2,{\bf Z}) acts as the modular transformation. The Ehlers SL(2,{\bf R}) and SL(2,{\bf Z}) similarly act on another torus whose conformal structure is induced through the Kramer-Neugebauer involution. Either of the Matzner-Misner and the Ehlers SL(2,{\bf Z}) can be embedded to a special T-duality, and if the former is chosen, then the Ehlers SL(2,{\bf Z}) is shown to act as the S-duality on the four-dimensional sector. As an application we obtain some new colliding string wave solutions by using this embedding as well as the inverse scattering method.Comment: 32 pages, revte

Monitoring metal stress in Puget Sound using metallothionein production in mussels in the nearshore

Toxic metals are common contaminants in sediments near industrial ports and in stormwater from urban areas throughout the Salish Sea. Although pollutant concentrations have been mapped in the sediments, waters and biota of Puget Sound for decades, equating these contaminant levels to biological impacts has been attempted infrequently. Moreover, many of these attempts at studying metal toxicity have not been applied to the ecologically and economically important nearshore area. As part of the Washington Department of Fish and Wildlife’s (WDFW) 2012-2013 MusselWatch Pilot Expansion Project, an effort to develop a nearshore biomonitoring protocol for Puget Sound, mussels of the same age and reared in the same location were transplanted to over 100 locations throughout Puget Sound in November 2012. Mussels were secured in quadruplicate batches in nylon netting suspended in 16x16x16 inch cages and anchored in the low intertidal by volunteers. The mussels were allowed to equilibrate with their surroundings for two months and retrieved in January 2013. All mussels were measured and weighed by WDFW staff and supervised volunteers, shucked and homogenized, and then frozen to await analysis. A portion of each homogenized sample was delivered to the University of Washington Tacoma for analysis of metallothioneins, cysteine-rich proteins used in the metal detoxification mechanism of mussels and other bivalves. Metallothioneins were derivatized with monobromobimane, separated by reverse phase high-pressure liquid chromatography, and analyzed with a fluorescence detector. Our results and correlations with parameters measured by other WDFW collaborators, including metal concentrations and growth characteristics, will be presented. With limited funding available for toxics remediation it is imperative to develop monitoring tools that measure biological impacts specific to metal stress, and to apply those tools to understanding ecological health in the nearshore