The status of the gannet in Scotland in 2013-14

All 16 Gannet colonies in Scotland were counted in 2013–14. Combined colony totals indicated that Scotland currently holds 243,505 apparently occupied sites (58% and 46% of the east Atlantic and world populations, respectively). Numbers were divided very unevenly between the colonies with Bass Rock (now the world’s largest colony), St Kilda and Ailsa Craig together holding 70% of the Scottish population. Gannets started to nest on Barra Head, Berneray in 2007 and breeding may now be regular on Rockall. Numbers at St Kilda, Sule Stack and Scar Rocks were stable, but all other colonies had increased, some spectacularly. Overall the Scottish population increased by 33% between 2003–04 and 2013–14 at an average rate of increase of 2.9% per annum. Although the Gannet appears less vulnerable to climate change than many other UK seabirds, the proposed construction of major offshore wind farms close to colonies in the North Sea and the imminent ban on fishery discards, could pose future threats to this species

Gannet surveys in north-west Scotland in 2013

A photographic survey of the Gannet colonies off the north-west coast of Scotland in 2013 found 60,290 Apparently Occupied Sites (AOS) on St Kilda, 11,230 AOS on Sula Sgeir, 5,280 AOS on the Flannan Islands, 4,550 AOS on Sule Stack and 1,870 AOS on Sule Skerry. Since 2004, numbers had increased rapidly at Sule Skerry and the Flannan Islands (47.4% per annum (pa) and 7.5% pa respectively), but had changed little at Sule Stack and St Kilda. The harvested colony on Sula Sgeir increased by 2.2% pa, reversing the trend over the previous 10 years during which the population declined at 1.2% pa

Ocean forcing of glacier retreat in the western Antarctic Peninsula

In recent decades, hundreds of glaciers draining the Antarctic Peninsula (63° to 70°S) have undergone systematic and progressive change. These changes are widely attributed to rapid increases in regional surface air temperature, but it is now clear that this cannot be the sole driver. Here, we identify a strong correspondence between mid-depth ocean temperatures and glacier-front changes along the ~1000-kilometer western coastline. In the south, glaciers that terminate in warm Circumpolar Deep Water have undergone considerable retreat, whereas those in the far northwest, which terminate in cooler waters, have not. Furthermore, a mid-ocean warming since the 1990s in the south is coincident with widespread acceleration of glacier retreat. We conclude that changes in ocean-induced melting are the primary cause of retreat for glaciers in this region

Staircases of wave-cut platforms in western central Portugal (Cape Mondego to Cape Espichel) – relevance as indicators of crustal uplift Escadarias de terraços marinhos em Portugal centro-ocidental (Cabo Mondego ao Cabo Espichel) – relevância como indicadores de soerguimento crustal

This study addresses coastal terrace staircases of western central Portugal (Cape Mondego to Cape Espichel). Below the culminant marine unit, that records the last episode of aggradation before the ongoing stage of incision, several terrace levels are identified. The following methodology was used: a) production of geomorphological maps, combining analysis of detailed MDT’s and aerial photos, with field surveys calibrated with GPS data; b) stratigraphic and sedimentological study of the sedimentary deposits associated with the marine platforms; c) luminescence dating. On each terrace staircase, the number of platforms and their elevations are different, indicating differential uplift. Quartz OSL provided age estimates up ca. 150 kyr and post-IR IRSL on K-feldspar up to ca. 700 kyr for the marine terraces under study. Using the culminant platform as reference and assuming that it is 3.6 Ma old, uplift rates were estimated as ranging from 0.071 m/ky to 0.019 m/ky. The ongoing luminescence dating will provide the uplift rates estimated for the lower and middle marine terrace

ESCADARIAS DE TERRAÇOS MARINHOS EM PORTUGAL CENTROOCIDENTAL – RELEVÂNCIA COMO INDICADORES DE SOERGUIMENTO CRUSTAL STAIRCASES OF WAVE-CUT PLATFORMS IN WESTERN CENTRAL PORTUGAL – RELEVANCE AS INDICATORS OF CRUSTAL UPLIFT

This study addresses the coastal terrace staircases of western central Portugal (Cape Mondego to Cape Espichel). Below the culminant marine unit that records the last episode of aggradation before the ongoing stage of incision, several terrace levels ar identified. The following methodology was used: a) production of geomorphological maps, combining analysis of detailed MDT’s and aerial photos, with field surveys calibrated with GPS; b) stratigraphic and sedimentological study of the sedimentary deposits associated with the marine platforms; c) luminescence dating. On each terrace staircase, the number of platforms and their elevations are different, indicating differential uplift. Quartz OSL provided age estimates up ca. 150 kyr and post-IR IRSL on K-feldspar up to ca. 700 kyr for the marine terraces under study. Using the culminant platform as reference and assuming that it is ca. 3.6 Ma old, uplift rates were estimated as ranging spatially from 0.071 m/ky to 0.019 m/ky. The ongoing luminescence dating will provide uplift rates estimated for the lower and middle marineterraces, clarifying if an acceleration of the crustal uplift is going on

An aerial survey of gannets on Westray, Orkney, in August 2016

An aerial survey of the Gannet colony on Westray, Orkney, was made for the first time on 16 August 2016 and found 1,560 AOS, contrasting with a land survey made on 30 May 2016, which found 1,020 AON. The aerial survey photographs show areas of the cliffs that are hidden from land. This, and the different count units used, are the main reasons for the higher aerial survey figure. A third population estimate was made by combining breeding productivity figures from an RSPB monitoring plot with chicks visible in the aerial photographs, which gave a calculated estimate of 1,306 AON. Whichever population estimate is used, it is clear that the colony is expanding rapidly. Future land counts will likely underestimate numbers so would best be combined with an occasional aerial survey to more precisely define colony size

Chasing the identification of ASCA Galactic Objects (ChIcAGO): An X-ray survey of unidentified sources in the galactic plane. I : Source sample and initial results

We present the Chasing the Identification of ASCA Galactic Objects (ChIcAGO) survey, which is designed to identify the unknown X-ray sources discovered during the ASCA Galactic Plane Survey (AGPS). Little is known about most of the AGPS sources, especially those that emit primarily in hard X-rays (2-10 keV) within the Fx 10-13 to 10-11 erg cm -2 s-1 X-ray flux range. In ChIcAGO, the subarcsecond localization capabilities of Chandra have been combined with a detailed multiwavelength follow-up program, with the ultimate goal of classifying the >100 unidentified sources in the AGPS. Overall to date, 93 unidentified AGPS sources have been observed with Chandra as part of the ChIcAGO survey. A total of 253 X-ray point sources have been detected in these Chandra observations within 3′ of the original ASCA positions. We have identified infrared and optical counterparts to the majority of these sources, using both new observations and catalogs from existing Galactic plane surveys. X-ray and infrared population statistics for the X-ray point sources detected in the Chandra observations reveal that the primary populations of Galactic plane X-ray sources that emit in the Fx 10-13 to 10-11 erg cm -2 s-1 flux range are active stellar coronae, massive stars with strong stellar winds that are possibly in colliding wind binaries, X-ray binaries, and magnetars. There is also another primary population that is still unidentified but, on the basis of its X-ray and infrared properties, likely comprises partly Galactic sources and partly active galactic nuclei.Peer reviewedSubmitted Versio

Topological Defects, Orientational Order, and Depinning of the Electron Solid in a Random Potential

We report on the results of molecular dynamics simulation (MD) studies of the classical two-dimensional electron crystal in the presence disorder. Our study is motivated by recent experiments on this system in modulation doped semiconductor systems in very strong magnetic fields, where the magnetic length is much smaller than the average interelectron spacing $a_0$, as well as by recent studies of electrons on the surface of helium. We investigate the low temperature state of this system using a simulated annealing method. We find that the low temperature state of the system always has isolated dislocations, even at the weakest disorder levels investigated. We also find evidence for a transition from a hexatic glass to an isotropic glass as the disorder is increased. The former is characterized by quasi-long range orientational order, and the absence of disclination defects in the low temperature state, and the latter by short range orientational order and the presence of these defects. The threshold electric field is also studied as a function of the disorder strength, and is shown to have a characteristic signature of the transition. Finally, the qualitative behavior of the electron flow in the depinned state is shown to change continuously from an elastic flow to a channel-like, plastic flow as the disorder strength is increased.Comment: 31 pages, RevTex 3.0, 15 figures upon request, accepted for publication in Phys. Rev. B., HAF94MD

The influence of gene expression time delays on Gierer-Meinhardt pattern formation systems

There are numerous examples of morphogen gradients controlling long range signalling in developmental and cellular systems. The prospect of two such interacting morphogens instigating long range self-organisation in biological systems via a Turing bifurcation has been explored, postulated, or implicated in the context of numerous developmental processes. However, modelling investigations of cellular systems typically neglect the influence of gene expression on such dynamics, even though transcription and translation are observed to be important in morphogenetic systems. In particular, the influence of gene expression on a large class of Turing bifurcation models, namely those with pure kinetics such as the Gierer–Meinhardt system, is unexplored. Our investigations demonstrate that the behaviour of the Gierer–Meinhardt model profoundly changes on the inclusion of gene expression dynamics and is sensitive to the sub-cellular details of gene expression. Features such as concentration blow up, morphogen oscillations and radical sensitivities to the duration of gene expression are observed and, at best, severely restrict the possible parameter spaces for feasible biological behaviour. These results also indicate that the behaviour of Turing pattern formation systems on the inclusion of gene expression time delays may provide a means of distinguishing between possible forms of interaction kinetics. Finally, this study also emphasises that sub-cellular and gene expression dynamics should not be simply neglected in models of long range biological pattern formation via morphogens