390 research outputs found
Advances in the cobalt-catalysed Pauson-Khand reaction : development of a sulfide-promoted, microwave-assisted protocol
The development of a sulfide-promoted, microwave-assisted Pauson-Khand reaction has enabled the formation of fused cyclopentenones using sub-stoichiometric quantities of a cobalt mediator over rapid reaction times and with no requirement for an external source of toxic carbon monoxide gas. This protocol displays applicability to both intra- and intermolecular Pauson-Khand reaction examples
Chiral Hierarchies, Compositeness and the Renormalization Group
A wide class of models involve the fine--tuning of significant hierarchies
between a strong--coupling ``compositeness'' scale, and a low energy dynamical
symmetry breaking scale. We examine the issue of whether such hierarchies are
generally endangered by Coleman--Weinberg instabilities. A careful study using
perturbative two--loop renormalization group methods finds that consistent
large hierarchies are not generally disallowed.Comment: 22 pp + 5 figs (uuencoded and submitted separately),
SSCL-Preprint-490; FERMI-PUB-93/035-
The Lost Library of Anne Conway
The philosopher Anne Conway (1631-1679) owned a large library, and her reading and book ownership shaped her intellectual life in distinctive ways. Until now, however, almost nothing has been known about the details of her reading or her book collection. Current scholarship assumes that her library, like that of her husband, the third Viscount Conway (c. 1623–1683), was lost or dispersed after her death. This article presents previously unrecognised evidence of Conway’s book ownership, and identifies, for the first time, the only books currently known to survive from her personal library. It traces their path to their current location in the Old Library of Jesus College, Cambridge, through the library of the soldier, book collector, and Cambridge Fellow Francis Sterling (c. 1652-1692). The article demonstrates that the newly identified books reveal previously unknown patterns of intellectual exchange amongst Conway’s family, and argues that they have significant implications for our understanding of her early intellectual development
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Synergism of anisotropic and computational NMR methods reveals the likely configuration of phormidolide A.
Characterization of the complex molecular scaffold of the marine polyketide natural product phormidolide A represents a challenge that has persisted for nearly two decades. In light of discordant results arising from recent synthetic and biosynthetic reports, a rigorous study of the configuration of phormidolide A was necessary. This report outlines a synergistic effort employing computational and anisotropic NMR investigation, that provided orthogonal confirmation of the reassigned side chain, as well as supporting a further correction of the C7 stereocenter
Wolbachia in the flesh: symbiont intensities in germ-line and somatic tissues challenge the conventional view of Wolbachia transmission routes
Symbionts can substantially affect the evolution and ecology of their hosts. The investigation of the tissue-specific distribution of symbionts (tissue tropism) can provide important insight into host-symbiont interactions. Among other things, it can help to discern the importance of specific transmission routes and potential phenotypic effects. The intracellular bacterial symbiont Wolbachia has been described as the greatest ever panzootic, due to the wide array of arthropods that it infects. Being primarily vertically transmitted, it is expected that the transmission of Wolbachia would be enhanced by focusing infection in the reproductive tissues. In social insect hosts, this tropism would logically extend to reproductive rather than sterile castes, since the latter constitute a dead-end for vertically transmission. Here, we show that Wolbachia are not focused on reproductive tissues of eusocial insects, and that non-reproductive tissues of queens and workers of the ant Acromyrmex echinatior, harbour substantial infections. In particular, the comparatively high intensities of Wolbachia in the haemolymph, fat body, and faeces, suggest potential for horizontal transmission via parasitoids and the faecal-oral route, or a role for Wolbachia modulating the immune response of this host. It may be that somatic tissues and castes are not the evolutionary dead-end for Wolbachia that is commonly thought
New possibilities for research on reef fish across the continental shelf of South Africa
[From introduction] Subtidal research presents numerous challenges that restrict the ability to answer fundamental ecological questions related to reef systems. These challenges are closely associated with traditional monitoring methods and include depth restrictions (e.g. safe diving depths for underwater visual census), habitat destruction (e.g. trawling), mortality of target species (e.g. controlled angling and fish traps), and high operating costs (e.g. remotely operated vehicles and large research vessels. Whereas many of these challenges do not apply or are avoidable in the shallow subtidal environment, the difficulties grow as one attempts to sample deeper benthic habitats. This situation has resulted in a paucity of knowledge on the structure and ecology of deep water reef habitats around the coast of South Africa and in most marine areas around the world. Furthermore, the inability to effectively survey deep water benthic environments has limited the capacity of researchers to investigate connectivity between shallow and deep water habitats in a standardised and comparable fashion
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