Fluorescent amplified fragment length polymorphism analysis of Norwegian Bacillus cereus and Bacillus thuringiensis soil isolates

We examined 154 Norwegian B. cereus and B. thuringiensis soil isolates (collected from five different locations), 8 B. cereus and 2 B. thuringiensis reference strains, and 2 Bacillus anthracis strains by using fluorescent amplified fragment length polymorphism (AFLP). We employed a novel fragment identification approach based on a hierarchical agglomerative clustering routine that identifies fragments in an automated fashion. No method is free of error, and we identified the major sources so that experiments can be designed to minimize its effect. Phylogenetic analysis of the fluorescent AFLP results reveals five genetic groups in these group 1 bacilli. The ATCC reference strains were restricted to two of the genetic groups, clearly not representative of the diversity in these bacteria. Both B. anthracis strains analyzed were closely related and affiliated with a B. cereus milk isolate (ATCC 4342) and a B. cereus human pathogenic strain (periodontitis). Across the entire study, pathogenic strains, including B. anthracis, were more closely related to one another than to the environmental isolates. Eight strains representing the five distinct phylogenetic clusters were further analyzed by comparison of their 16S rRNA gene sequences to confirm the phylogenetic status of these groups. This analysis was consistent with the AFLP analysis, although of much lower resolution. The innovation of automated genotype analysis by using a replicated and statistical approach to fragment identification will allow very large sample analyses in the future

Towards granular hydrodynamics in two-dimensions

We study steady-state properties of inelastic gases in two-dimensions in the presence of an energy source. We generalize previous hydrodynamic treatments to situations where high and low density regions coexist. The theoretical predictions compare well with numerical simulations in the nearly elastic limit. It is also seen that the system can achieve a nonequilibrium steady-state with asymmetric velocity distributions, and we discuss the conditions under which such situations occur.Comment: 8 pages, 9 figures, revtex, references added, also available from http://arnold.uchicago.edu/?ebn

Toroidal optical dipole traps for atomic Bose-Einstein condensates using Laguerre-Gaussian beams

We theoretically investigate the use of red-detuned Laguerre-Gaussian (LG) laser beams of varying azimuthal mode index for producing toroidal optical dipole traps in two-dimensional atomic Bose-Einstein condensates. Higher-order LG beams provide deeper potential wells and tighter confinement for a fixed toroid radius and laser power. Numerical simulations of the loading of the toroidal trap from a variety of initial conditions is also given.Comment: 12 pages, 5 figures, submitted to Phys. Rev.

Use of an Anaerobic Chamber Environment for the Assay of Endogenous Cellular Protein-Tyrosine Phosphatase Activities

Protein-tyrosine phosphatases (PTPases) have a catalytic cysteine residue whose reduced state is integral to the reaction mechanism. Since exposure to air can artifactually oxidize this highly reactive thiol, PTPase assays have typically used potent reducing agents to reactivate the enzymes present; however, this approach does not allow for the measurement of the endogenous PTPase activity directly isolated from the in vivo cellular environment. Here we provide a method for using an anaerobic chamber to preserve the activity of the total PTPase complement in a tissue lysate or of an immunoprecipitated PTPase homolog to characterize their endogenous activation state. Comparison with a sample treated with biochemical reducing agents allows the determination of the activatable (reducible) fraction of the endogenous PTPase pool

Highly anisotropic Bose-Einstein condensates: crossover to lower dimensionality

We develop a simple analytical model based on a variational method to explain the properties of trapped cylindrically symmetric Bose-Einstein condensates (BEC) of varying degrees of anisotropy well into regimes of effective one dimension (1D) and effective two dimension (2D). Our results are accurate in regimes where the Thomas-Fermi approximation breaks down and they are shown to be in agreement with recent experimental data.Comment: 4 pages, 2 figures; significantly more new material added; title and author-list changed due to changes in conten

Dynamic interaction of PTP mu with multiple cadherins in vivo

There is a growing body of evidence to implicate reversible tyrosine phosphorylation as an important mechanism in the control of the adhesive function of cadherins. We previously demonstrated that the receptor protein tyrosine phosphatase PTP mu associates with the cadherin-catenin complex in various tissues and cells and, therefore, may be a component of such a regulatory mechanism (Brady-Kalnay, S.M., D.L. Rimm, and N.K. Tonks. 1995. J. Cell Biol. 130:977-986). In this study, we present further characterization of this interaction using a variety of systems. We observed that PTP mu interacted with N-cadherin, E-cadherin, and cadherin-4 (also called R-cadherin) in extracts of rat lung. We observed a direct interaction between PTP mu, and E-cadherin after coexpression in Sf9 cells. In WC5 cells, which express a temperature-sensitive mutant form of v-Src, the complex between PTP mu and E-cadherin was dynamic, and conditions that resulted in tyrosine phosphorylation of E-cadherin were associated with dissociation of PTP mu from the complex. Furthermore, we have demonstrated that the COOH-terminal 38 residues of the cytoplasmic segment of E-cadherin was required for association with PTP mu in WC5 cells. Zondag et al. (Zondag, G., W. Moolenaar, and M. Gebbink. 1996. J. Cell Biol. 134: 1513-1517) have asserted that the association we observed between PTP mu and the cadherin-catenin complex in immunoprecipitates of the phosphatase arises from nonspecific cross-reactivity between BK2, our antibody to PTP mu, and cadherins. In this study we have confirmed our initial observation and demonstrated the presence of cadherin in immunoprecipitates of PTP mu. obtained with three antibodies that recognize distinct epitopes in the phosphatase. In addition, we have demonstrated directly that the anti-PTP mu antibody BK2 that we used initially did not cross-react with cadherin. Our data reinforce the observation of an interaction between PTP mu, and E-cadherin in vitro and in vivo, further emphasizing the potential importance of reversible tyrosine phosphorylation in regulating cadherin function

Drivers and outcomes of work alienation: reviving a concept

This article sheds new light on an understudied construct in mainstream management theory, namely, work alienation. This is an important area of study because previous research indicates that work alienation is associated with important individual and organizational outcomes. We tested four antecedents of work alienation: decision-making autonomy, task variety, task identity, and social support. Moreover, we examined two outcomes of alienation: deviance and performance, the former measured 1 year after the independent variables were measured, and the latter as rated by supervisors. We present evidence from a sample of 283 employees employed at a construction and consultancy organization in the United Kingdom. The results supported the majority of our hypotheses, indicating that alienation is a worthy concept of exploration in the management sciences

Collective oscillations of a 1D trapped Bose gas

Starting from the hydrodynamic equations of superfluids, we calculate the frequencies of the collective oscillations of a harmonically trapped Bose gas for various 1D configurations. These include the mean field regime described by Gross-Pitaevskii theory and the beyond mean field regime at small densities described by Lieb-Liniger theory. The relevant combinations of the physical parameters governing the transition between the different regimes are discussed.Comment: 4 pages, 2 figure

Density Functional Theory of Bosons in a Trap

A time-dependent Kohn-Sham (KS) like theory is presented for N bosons in thre e and lower-dimensional traps. We derive coupled equations, which allow one to calculate the energies of elementary excitations. A rigorous proof is given to show that the KS like equation correctly describes properties of the one-dimensional condensate of impenetrable bosons in a general time-dependent harmonic trap in the larg N limit.Comment: 10 page