Manifest superconformal covariance in six-dimensional (2,0) theory

A superconformal generalization of Dirac's formalism for manifest conformal covariance is presented and applied to the free (2,0) tensor multiplet field theory in six dimensions. A graded symmetric superfield, defined on a supercone in a higher-dimensional superspace is introduced. This superfield transforms linearly under the transformations of the supergroup OSp(8*|4), which is the superconformal group of the six-dimensional (2,0) theory. We find the relationship between the new superfield and the conventional (2,0) superfields in six dimensions and show that the implied superconformal transformation laws are correct. Finally, we present a manifestly conformally covariant constraint on the supercone, which reduces to the ordinary differential constraint for the superfields in the six-dimensional space-time.Comment: 12 pages, LaTeX. v2: minor clarification adde

BPS surface observables in six-dimensional (2,0) theory

The supergroup OSp(8*|4), which is the superconformal group of (2,0) theory in six dimensions, is broken to the subgroup OSp(4|2)xOSp(4|2) by demanding the invariance of a certain product in a superspace with eight bosonic and four fermionic dimensions. We show that this is consistent with the symmetry breaking induced by the presence of a flat two-dimensional BPS surface in the usual (2,0) superspace, which has six bosonic and sixteen fermionic dimensions.Comment: 9 pages, LaTeX. v2: reference adde

Supersymmetric coupling of a self-dual string to a (2,0) tensor multiplet background

We construct an interaction between a (2,0) tensor multiplet in six dimensions and a self-dual string. The interaction is a sum of a Nambu-Goto term, with the tension of the string given by the modulus of the scalar fields of the tensor multiplet, and a non-local Wess-Zumino term, that encodes the electromagnetic coupling of the string to the two-form gauge field of the tensor multiplet. The interaction is invariant under global (2,0) supersymmetry, modulo the equations of motion of a free tensor multiplet. It is also invariant under a local fermionic kappa-symmetry, as required by the BPS-property of the string.Comment: 12 pages, LaTe

Thomson scattering of chiral tensors and scalars against a self-dual string

We give a non-technical outline of a program to study the (2,0) theories in six space-time dimensions. Away from the origin of their moduli space, these theories describe the interactions of tensor multiplets and self-dual spinning strings. We argue that if the ratio between the square of the energy of a process and the string tension is taken to be small, it should be possible to study the dynamics of such a system perturbatively in this parameter. As a first step in this direction, we perform a classical computation of the amplitude for scattering chiral tensor and scalar fields (i.e. the bosonic part of a tensor multiplet) against a self-dual spinnless string.Comment: 24 pages, LaTeX, 2 figures. v2: added discussion on supersymmetry in Ch.

Free tensor multiplets and strings in spontaneously broken six-dimensional (2,0) theory

We first review the representations of the six-dimensional (2,0) superalgebra on a free tensor multiplet and on a free string. We then construct a supersymmetric Lagrangian describing a free tensor multiplet. (It also includes a decoupled anti self-dual part of the three-form field strength.) This field theory is then rewritten in variables appropriate for analyzing a situation where the R-symmetry is spontaneously broken by the vacuum expectation values of the scalar moduli fields. Finally, we construct a supersymmetric and kappa-symmetric action for a free string.Comment: 15 pages, LaTe

Polymer Displacement and Supermacroporous Cryogels - Two New Tools in Chromatographic Separation of Biomolecules and Bioparticles

Production of protein is often accompanied with difficulties due to the large amounts of different biological material resulting from fermentation. This makes purification necessary and affinity chromatography is usually involved as being biospecific, although suffering from limitations as low recovery due to ineffective elution and inability to handle particulate materials. Displacement of lactate dehydrogenase (LDH) from dye-affinity matrices with poly(ethyleneimine) (PEI) resulted in better recoveries and sharper elution profiles than traditional non-specific elution but with unchanged purification factors. Hence, displacement with PEI is a promising strategy for eluting proteins with reported low recoveries in dye-affinity chromatography. Displacement of (His)6-LDH, a hexahistidine-tagged thermostable LDH originating from a thermophilic bacterium, was carried out using a synthetic copolymer of vinyl imidazole and vinyl caprolactam as displacer from an immobilized metal affinity chromatography (IMAC) column. Complete elution of bound (His)6-LDH from Cu2+-imminodiacetic acid Sepharose was achieved at a co-polymer concentration of 5 mg/ml, corresponding to 3.7 mM imidazole units, while 160 mM free imidazole was needed to obtain the same result. Thus, efficiency could be significantly improved by a polymeric displacer having interacting groups of the same chemical nature as the corresponding low-molecular mass displacer. Continuous supermacroporous chromatographic columns with anion exchange ligands (2-(dimethylamino)ethyl group) and IMAC ligands (Cu2+-loaded iminodiacetic acid) have been developed allowing binding of E. coli cells and elution of bound cells with high recoveries and retained viability as well as direct capture of enzyme from non-clarified crude cell homogenate at high flow rates without mechanical obstruction. These poly(acrylamide)-based matrices were produced by radical co-polymerization of monomers in aqueous solution frozen inside a column (cryogelation). After thawing, the column contains a continuous cryogel matrix with interconnected 10 - 100 mm pores. These large pores make processing of particulate-containing material without blocking possible. Purification of (His)6-LDH from non-clarified crude extract without preliminary filtration or centrifugation was possible on the IMAC cryogel column. Totally, 210 ml crude homogenate was processed on a single five ml supermacroporous column at flow speeds up to 12.5 ml/min (625 cm/h) without impairment of column properties. E. coli cells bound to an IMAC-column were eluted with 80 % recovery using either 10 mM imidazole or 20 mM EDTA solutions and cells bound to an ion-exchange column at low ionic strength were eluted with 70 - 80% recovery at NaCl concentrations of 0.35 - 0.40 M, while it was possible for cells to pass unhindered through a column without ligands. Cells maintained viability after the chromatographic procedures. Mechanically the cryogel adsorbent is very stable. The matrix could easily be removed from the column, dried at 70 °C and kept in a dry state. After rehydration, (His)6-LDH was purified as efficiently as on a newly prepared column. Materials for manufacturing the cryogels are cheap, available and are simply mixed and frozen under specified conditions. Altogether, these qualities reveal that supermacroporous continuous cryogels is a very interesting alternative to existing methods of protein purification from particulate-containing crude extracts as well as an exciting new support for handling of microbial cells in a chromatographic mode

Usage of Business Intelligence : Testing the Technology Acceptance Model on a BI System

Business Intelligence (BI) has become an essential part of the modern enterprise, and what used to be thought of as a luxury is now a matter of survival. Recent economic developments have forced companies to rethink their IT investment strategy. BI investments are now targeting the majority of people in the organisation instead of a select few. Thus, it is important to understand why users of a BI system choose to accept and use the system. Previous research has established the Technology Acceptance Model (TAM) as one of the most powerful and parsimonious models explaining user acceptance and usage behaviour of information technologies. This quantitative study replicates the original TAM study with the purpose to increase the understanding of BI usage, and investigates the behaviour of the users of the BI system QlikView in the case company GE Healthcare. The results showed a lower explanatory power for the model when compared to previous research. This indicates that how useful a user perceives a BI system to be does not affect the amount of usage to the same extent as predicted by TAM. Possible causes for this are discussed, with an emphasis on the influence of what tasks a user is confronted with and the measurement of system use

On the Characteristics of WWW Traffic and the Relevance to ATM

This article is written under the Project "Modelling of Bursty Traffics