Friends, Neighbours and Distant Partners: Extending or Decentring Family Relationships?

[No abstract][No keywords]

High throughput particle analysis: combining dielectrophoretic particle focussing with confocal optical detection

A microflow cytometer has been fabricated that detects and counts fluorescent particles flowing through a microchannel at a high speed based upon their fluorescence emission intensity. Dielectrophoresis is used to continuously focus particles within the flowing fluid stream into the centre of the device, which is 40 μm high and 250 μm wide. The method ensures that all the particles pass through an interrogation region approximately 5 μm in diameter, which is created by focusing a beam of light into a spot. The functioning of the device was demonstrated by detecting and counting fluorescent latex particles at a rate of up to 250 particles/s. A mixture of three different populations of latex particle was used, each sub-population with a distinct level of fluorescent intensity. The device was evaluated by comparison with a conventional fluorescent activated cell sorter (FACS) and numerical simulation demonstrated that for 6 mico m beads, and for this design of chip the theoretical throughput is of the order of 1000 particles/s (corresponding to a particle velocty of 1 mm/s)

Re-Imagining Images of Organization: A Conversation With Gareth Morgan

In this article, we review the metaphors presented by Morgan in Images of Organization and highlight how they simultaneously act as “relatively static reflections” (i.e., they provide a history of organization theory) and “relatively dynamic projections” (i.e., stimulating the formulation of further organizational images). We also discuss the potential for new organizational metaphors and consider two specific metaphors (i.e., the “global brain” and “organization as media”). We also challenge the established punctuated metaphorical process (i.e., a transfer from a metaphorical source domain to an organizational target domain), propose a dynamic perspective of interchange (i.e., source domain to target domain to source domain and so on), and develop the notion of multidirectionality (i.e., two-way projections between target and source domains)

HST/NICMOS Observations of Fast Infrared Flickering in the Microquasar GRS 1915+105

We report infrared observations of the microquasar GRS 1915+105 using the NICMOS instrument of the Hubble Space Telescope during 9 visits in April-June 2003. During epochs of high X-ray/radio activity near the beginning and end of this period, we find that the $1.87$\um infrared flux is generally low ($\sim 2$ mJy) and relatively steady. However, during the X-ray/radio ``plateau'' state between these epochs, we find that the infrared flux is significantly higher ($\sim 4-6$ mJy), and strongly variable. In particular, we find events with amplitudes $\sim 20-30$% occurring on timescales of $\sim 10-20$s (e-folding timescales of $\sim 30$s). These flickering timescales are several times faster than any previously-observed infrared variability in GRS 1915+105 and the IR variations exceed corresponding X-ray variations at the same ($\sim 8s$) timescale. These results suggest an entirely new type of infrared variability from this object. Based on the properties of this flickering, we conclude that it arises in the plateau-state jet outflow itself, at a distance $<2.5$ AU from the accretion disk. We discuss the implications of this work and the potential of further flickering observations for understanding jet formation around black holes.Comment: 19 pages, incl. 4 figures; accepted for publication in Ap

Cohesin cleavage by separase is enhanced by a substrate motif distinct from the cleavage site.

Chromosome segregation begins when the cysteine protease, separase, cleaves the Scc1 subunit of cohesin at the metaphase-to-anaphase transition. Separase is inhibited prior to metaphase by the tightly bound securin protein, which contains a pseudosubstrate motif that blocks the separase active site. To investigate separase substrate specificity and regulation, here we develop a system for producing recombinant, securin-free human separase. Using this enzyme, we identify an LPE motif on the Scc1 substrate that is distinct from the cleavage site and is required for rapid and specific substrate cleavage. Securin also contains a conserved LPE motif, and we provide evidence that this sequence blocks separase engagement of the Scc1 LPE motif. Our results suggest that rapid cohesin cleavage by separase requires a substrate docking interaction outside the active site. This interaction is blocked by securin, providing a second mechanism by which securin inhibits cohesin cleavage

Quantum dot labelling of adenovirus allows for highly sensitive single cell flow and imaging cytometry

A quantum dot method for highly efficient labelling of single adenoviral particles is developed. The technique has no impact on viral fitness and allows the imaging and tracking of virus binding and internalisation events using a variety of techniques including imaging cytometry and confocal microscopy. The method is applied to characterise the tropism of different adenoviral vectors

Cape Vulture Gyps coprotheres caught in gin trap

No Abstrac