Enhancement of Ca2+-dependent outward current in sheep bladder myocytes by evans blue dye.

Whole-cell and inside-out patch-clamp techniques were used to assess the action of a well-known dye, Evans blue, on membrane currents in bladder isolated smooth muscle cells from sheep. In whole cells Evans blue dose-dependently increased the outward current by up to fivefold. In contrast, Evans blue had no effect on inward Ca2+ current. The effect on outward current was abolished or reduced if the cells were bathed in Ca2+-free solution, iberiotoxin (5 x 10(-8) M), or charybdotoxin (5 x 10(-8) M), but was unaffected by externally applied caffeine (5 mM) or in cells exposed to heparin (1 mg/ml) via the patch pipette. In inside-out patches bathed in a Ca2+ concentration of 5 x 10(-7) M, Evans blue (10(-4) M) increased the open probability of large-conductance (298-pS) Ca2+-dependent K+ channels (BK channels), shifting the half maximal-activation voltage by -70 mV. We conclude that Evans blue dye acts as an opener of BK channels.

A UKST survey of blue objects towards the Galactic centre - seven additional fields

We are searching for early-type stars towards the Galactic centre which are potentially young objects situated within the inner few kiloparsecs of the disk. Photographic photometry from the UK Schmidt Telescope has been used to identify the bluest candidates in nineteen Schmidt fields (centred close to the Galactic centre). We have previously obtained FLAIR low dispersion spectroscopy for three of these fields to estimate spectral types and here we present spectroscopy for an additional seven fields. Combining the results for all ten fields, 56 stars were initially classified as early-B type. Estimates of the equivalent widths of their Balmer and He I lines have been used to estimate atmospheric parameters and 32 targets have effective temperatures greater than or equal to 17 000 K (corresponding to a spectral type of B3 or earlier). The spectra of seven of these targets also have absorption lines due to O II and Si III and can be reliably classified as early- B type. Additionally 78 stars have estimated effective temperatures between 11 000 and 16 000 K with a further a further 50 objects identified as late-B (or early-A) type. All but two of the early B-type candidates have magnitudes in the range 12.0 less than or equal to V less than or equal to 16.0, and our best estimates of their distance suggest that they could be close to (i.e. R-g <3 kpc), or even beyond the Galactic centre.

Luminous blue variables as the progenitors of supernovae with quasi-periodic radio modulations

The interaction between supernova ejecta and circumstellar matter, arising from previous episodes of mass loss, provides us with a means of constraining the progenitors of supernovae. Radio observations of a number of supernovae show quasi-periodic deviations from a strict power-law decline at late times. Although several possibilities have been put forward to explain these modulations, no single explanation has proven to be entirely satisfactory. Here we suggest that Luminous blue variables undergoing S-Doradus type variations give rise to enhanced phases of mass loss that are imprinted on the immediate environment of the exploding star as a series of density enhancements. The variations in mass loss arise from changes in the ionization balance of Fe, the dominant ion that drives the wind. With this idea, we find that both the recurrence timescale of the variability and the amplitude of the modulations are in line with the observations. Our scenario thus provides a natural, single-star explanation for the observed behaviour that is, in fact, expected on theoretical grounds.

Problems with identifying the '8200-year cold event' in terrestrial records of the Atlantic seaboard: a case study from Dooagh, Achill Island, Ireland.

The Northern Hemisphere cooling event 8200 years ago is believed to represent the last known major freshwater pulse into the North Atlantic as a result of the final collapse of the North American Laurentide ice sheet. This pulse of water is generally believed to have occurred independently of orbital variations and provides an analogue for predicted increases in high-latitude precipitation and ice melt as a result of anthropogenically driven future climate change. The precise timing, duration and magnitude of this event, however, are uncertain, with suggestions that the 100-yr meltwater cooling formed part of a longer-term cold period in the early Holocene. Here we undertook a multiproxy, high-resolution investigation of a peat sequence at Dooagh, Achill Island, on the west coast of Ireland, to determine whether the 8200-year cold event impacted upon the terrestrial vegetation immediately downwind of the proposed changes in the North Atlantic. We find clear evidence for an oscillation in the early Holocene using various measures of pollen, indicating a disruption in the vegetation leading to a grassland-dominated landscape, most probably driven by changes in precipitation rather than temperature. Radiocarbon dating was extremely problematic, however, with bulk peat samples systematically too young for the North Atlantic event, suggesting significant contamination from downward root penetration. The sustained disruption to vegetation over hundreds of years at Dooagh indicates the landscape was impacted by a long-term cooling event in the early Holocene, and not the single century length 8200-year meltwater event proposed in many other records in the North Atlantic region.

Between the devil and the deep blue sea: Nationality, power and symbolic trade-offs among evangelical Protestants in contemporary Northern Ireland

National identity is symbolically complex configuration, with shifts of emphasis and reprioritisations of content negotiated in contexts of power. This paper shows how they occur in one post-conflict situation - Northern Ireland - among some of the most extreme of national actors - evangelical Protestants. In-depth interviews reveal quite radical shifts in the content of their British identity and in their understanding of and relation to the Irish state, with implications for their future politics. The implications for understanding ethno-religious nationalism, nationality shifts and the future of Northern Ireland are drawn out.

Long-term hydroclimatic change and interannual variability in water sources, Apex River (Iqaluit), Baffin Island, Nunavut

The eastern Canadian Arctic is home to Canada’s largest Indigenous population, which depends on local freshwater sources for drinking water. However, small watersheds have rarely been analyzed for long-term hydrologic response to changing climate. This study aims to address this issue by examining the Apex River, a small watershed with a long hydroclimatic record, near Iqaluit, Nunavut. Particular emphasis was placed on the long-term changes in climate and river discharge, and the seasonal variability of water sources between two snapshots in time, 1983 and 2013. Long-term hydrological data were obtained from gauge station 10UH002, operated by Environment and Climate Change Canada, and long-term meteorological data were acquired from Environment Canada–operated stations near Iqaluit Airport. Breakpoint analysis suggested that long-term mean annual surface air temperatures have increased since 1994. In contrast, no long-term total precipitation or annual discharge changes were observed. However, river flow initiation and cessation analyses of the Apex River flow season indicates that flow extended into the autumn since the 2000s. The 2013 flow season lasted 44 days longer than the 1983 flow season. Systematic river sampling was undertaken throughout the 2013 thaw season to determine contributing proportions of event (snowmelt or rainfall) and pre-event (baseflow) water to river runoff. Results from the stable isotope hydrograph separation for 2013 were compared to findings for 1983. Snow was the main source of water to the river during the snowmelt period in 1983 and 2013, however baseflow was still an important contributor. Although there was high similarity of water sources early in the season in 1983 and 2013, the two years differed during the autumn. In 2013 there was a high rainfall runoff response that was not present in 1983, suggesting high release of late-season sub-surface water storage and an increased sensitivity to late-season rainfall events in 2013. This research provides insights into the hydrologic response of the Apex River to long-term climatic change, and highlights the need for high-quality precipitation and discharge data for effective long-term hydrological assessment.