Theory of preparation and relaxation of a p-orbital atomic Mott insulator

We develop a theoretical framework to understand the preparation and relaxation of a metastable Mott insulator state within the first excited band of a 1D optical lattice. The state is loaded by "lifting" atoms from the ground to the first excited band by means of a stimulated Raman transition. We determine the effect of pulse duration on the accuracy of the state preparation for the case of a Gaussian pulse shape. Relaxation of the prepared state occurs in two major stages: double-occupied sites occurring due to quantum fluctuations initially lead to interband transitions followed by a spreading of particles in the trap and thermalization. We find the characteristic relaxation times at the earliest stage and at asymptotically long times approaching equilibrium. Our theory is applicable to recent experiments performed with 1D optical lattices [T. M\"uller, S. F\"olling, A. Widera, and I. Bloch, Phys. Rev. Lett. \textbf{99}, 200405 (2007)].Comment: 27 pages, 23 figures: Edited figures, added reference

The Plunder of Maqdala: Ethical Concerns Around Belongings and Ancestral Remains in Museums

During the colonial period, museums did not just passively benefit from the plunder of human remains and culturally sacred items. When Britain sent a punitive military expedition to Abyssinia (now Ethiopia) in 1863, it was accompanied by Richard Holmes, a staff member of the British Museum, whose purchase of loot from the expeditionary force institutionalised the plunder of cultural heritage. His inclusion in the expeditionary force was carefully planned, though the belongings he took — mainly manuscripts, religious items and emblems of power belonging to the Ethiopian royal family — were not the intended focus of his participation. Whilst the UK’s 2004 Human Tissue Act had a beneficial impact on the treatment of human remains in museums, objects belonging to colonised people are often still positioned as artworks or artefacts, evidencing ignorance of the deep personal and spiritual links that connect them back to their communities of origin. This article draws on our professional experience of curation and research in museums and libraries, as well as the impact of ICOM’s new Museum Definition on our practice. Joint research on the Maqdala expedition led us to question assumptions about the legacy of empire in museums and to scrutinise unexpected connections in the history of museum collections. This article addresses the problematic relationship between collecting and imperial power, the false dichotomy between ‘artefacts’ (belongings) and ‘human remains’ (ancestors) and the need to decolonise collections through further research and the recognition of ongoing cultural and physical violence

Solitary-wave description of condensate micro-motion in a time-averaged orbiting potential trap

We present a detailed theoretical analysis of micro-motion in a time-averaged orbiting potential trap. Our treatment is based on the Gross-Pitaevskii equation, with the full time dependent behaviour of the trap systematically approximated to reduce the trapping potential to its dominant terms. We show that within some well specified approximations, the dynamic trap has solitary-wave solutions, and we identify a moving frame of reference which provides the most natural description of the system. In that frame eigenstates of the time-averaged orbiting potential trap can be found, all of which must be solitary-wave solutions with identical, circular centre of mass motion in the lab frame. The validity regime for our treatment is carefully defined, and is shown to be satisfied by existing experimental systems.Comment: 12 pages, 2 figure

Self-consistent pedestal prediction for JET-ILW in preparation of the DT campaign

The self-consistent core-pedestal prediction model of a combination of EPED1 type pedestal prediction and a simple stiff core transport model is able to predict Type I ELMy (edge localized mode) pedestals of a large JET-ILW (ITER-like wall) database at the similar accuracy as is obtained when the experimental global plasma beta is used as input. The neutral penetration model [R. J. Groebner et al., Phys. Plasmas 9, 2134 (2002)] with corrections that take into account variations due to gas fueling and plasma triangularity is able to predict the pedestal density with an average error of 15%. The prediction of the pedestal pressure in hydrogen plasma that has higher core heat diffusivity compared to a deuterium plasma with similar heating and fueling agrees with the experiment when the isotope effect on the stability, the increased diffusivity, and outward radial shift of the pedestal are included in the prediction. However, the neutral penetration model that successfully predicts the deuterium pedestal densities fails to predict the isotope effect on the pedestal density in hydrogen plasmas

Mining microbial genomes for new natural products and biosynthetic pathways

Analyses of microbial genome sequences have revealed numerous examples of ‘cryptic’ or ‘orphan’ biosynthetic gene clusters, with the potential to direct the production of novel, structurally complex natural products. This article summarizes the various methods that have been developed for discovering the products of cryptic biosynthetic gene clusters in microbes and gives an account of my group's discovery of the products of two such gene clusters in the model actinomycete Streptomyces coelicolor M145. These discoveries hint at new mechanisms, roles and specificities for natural product biosynthetic enzymes. Our efforts to elucidate these are described. The identification of new secondary metabolites of S. coelicolor raises the question: what is their biological function? Progress towards answering this question is also summarized

The insect pathogen Serratia marcescens Db10 uses a hybrid non-ribosomal peptide synthetase-polyketide synthase to produce the antibiotic althiomycin

There is a continuing need to discover new bioactive natural products, such as antibiotics, in genetically-amenable micro-organisms. We observed that the enteric insect pathogen, Serratia marcescens Db10, produced a diffusible compound that inhibited the growth of Bacillis subtilis and Staphyloccocus aureus. Mapping the genetic locus required for this activity revealed a putative natural product biosynthetic gene cluster, further defined to a six-gene operon named alb1-alb6. Bioinformatic analysis of the proteins encoded by alb1-6 predicted a hybrid non-ribosomal peptide synthetase-polyketide synthase (NRPS-PKS) assembly line (Alb4/5/6), tailoring enzymes (Alb2/3) and an export/resistance protein (Alb1), and suggested that the machinery assembled althiomycin or a related molecule. Althiomycin is a ribosome-inhibiting antibiotic whose biosynthetic machinery had been elusive for decades. Chromatographic and spectroscopic analyses confirmed that wild type S. marcescens produced althiomycin and that production was eliminated on disruption of the alb gene cluster. Construction of mutants with in-frame deletions of specific alb genes demonstrated that Alb2-Alb5 were essential for althiomycin production, whereas Alb6 was required for maximal production of the antibiotic. A phosphopantetheinyl transferase enzyme required for althiomycin biosynthesis was also identified. Expression of Alb1, a predicted major facilitator superfamily efflux pump, conferred althiomycin resistance on another, sensitive, strain of S. marcescens. This is the first report of althiomycin production outside of the Myxobacteria or Streptomyces and paves the way for future exploitation of the biosynthetic machinery, since S. marcescens represents a convenient and tractable producing organism

Anti-microfouling Activity of Glycomyces sediminimaris UTMC 2460 on Dominant Fouling Bacteria of Iran Marine Habitats

Discovery of environmentally safe anti-fouling agent is currently of considerable interest, due to the continuous impact of biofoulers on the marine habitats and the adverse effects of biocides on the environment. This study reports the anti-adhesion effect of marine living Actinobacteria against fouling strains isolated from submerged panels in marine environments of Iran. The extract of Glycomyces sediminimaris UTMC 2460 affected the biofilm formation of Kocuria sp. and Mesorhizobium sp., as the dominant fouling agents in this ecosystem, up to 93.2% and 71.4%, respectively. The metabolic activity of the fouler bacteria was reduced by the extract up to 17 and 9%, respectively. This indicated the bactericidal potency of the extract on cells in the biofilm state that enables the compound to be effective even once the biofilms are established in addition to the inhibition of biofilm initiation. Moreover, extra polymeric substance (EPS) production by fouling bacteria was reduced by 60–70%. The absence of activities against fouling bacteria in suspension and also the absence of toxic effect on Artemia salina showed the harmless ecological effect of the anti-microfouling extract on the prokaryotic and eukaryotic microflora of the studied Iran marine ecosystem. Metabolic profiling of G. sediminimaris UTMC 2460 revealed the presence of compounds with molecular formulae matching those of known anti-fouling diketopiperazines as major components of the extract. These results suggest that the extract of Glycomyces sediminimaris UTMC 2460 could be used as a potentially eco-friendly viable candidate in comparison to the synthetic common commercial anti-microfouling material to prevent the fouling process in marine habitats of Iran