156 research outputs found
Important bird areas in Africa and associated islands : priority sites for conservation Fishpool L. D. C. & Evans M. I. (eds). Newbury and Cambridge, UK : Pisces. Publications and Birdlife International (Birdlife Conservation Series N° 11), (2001)
No full textVidal Éric. Important bird areas in Africa and associated islands : priority sites for conservation Fishpool L. D. C. & Evans M. I. (eds). Newbury and Cambridge, UK : Pisces. Publications and Birdlife International (Birdlife Conservation Series N° 11), (2001). In: Ecologia mediterranea, tome 28 n°2, 2002. p. 111
Minding the protection gap: estimates of species' range sizes and holes in the Protected Area network
No full text[No abstract available
The broadening of SOL profiles in JET tritium plasma and its impact on machine operation
No full textUnusually high power loads on the beryllium limiter caused by neutral beam re-ionisation, and much cooler divertor target surfaces were observed during the recent JET tokamak tritium campaign. As both phenomena are driven by scrape-off layer (SOL) physics, the SOL features of 72 tritium H-mode discharges and their deuterium references have been studied. The majority (70) of tritium H-mode discharges had exponentially decaying SOL profiles. The tritium plasmas are observed to have increased separatrix density and collisionality compared to their deuterium references. This is associated with ≈ 2 − 3 times broader SOL width for both density and temperature profiles. This is consistent with previous observations in highly collisional deuterium H-mode plasma on the ASDEX Upgrade tokamak (Sun et al 2015 Plasma Phys. Control. Fusion 57 075005) and interpreted as high collisionality enhancing cross-field transport across the separatrix and resulting in the broadening of near SOL above a critical value. The other two tritium H-mode discharges had near flat SOL density profiles, similar to the so-called ‘density shoulder formation’ observed in L-mode plasma. The SOL collisionality of these two pulses lies within the range of T pulses without density shoulder formation. This supports the conclusion of previous studies (Vianello et al 2017 Nucl. Fusion 57 116014; Wynn et al 2018 Nucl. Fusion 58 056001) that increased collisionality is not sufficient for the formation of a ‘density shoulder’ and additional factors, likely divertor condition or interaction with neutrals, are required. JET tritium plasma provides evidence of favourable and unfavourable effects of enhanced cross-field SOL transport on machine operation. The larger limiter power loads due to re-ionisation of neutral beam injection observed in the T pulses relative to their D references has been shown to be consistent with the combined effects of the broadening of the SOL profile and larger beam ion Larmor radius. The enhanced cross-field particle transport and the resulting broader SOL width provides more particles to ionize the fast Beam neutrals, causing the unfavourable power load issue on the beryllium limiter. The broader near SOL profiles of the T plasma spreads the heat load over a larger area and, together with the increased separatrix density, results in a favourably cooler divertor target surface
Figures 47-63 from: Popov GB, Fishpool LDC, Rowell CHF (2019) A review of the Acridinae s. str. (Orthoptera: Acridoidea: Acrididae) of eastern Africa with taxonomic changes and description of new taxa. Journal of Orthoptera Research 28(2): 37-105. https://doi.org/10.3897/jor.28.29312
No full textFigures 47-63 Figs 47–56.Afrophlaeoba genus group; comparison with Tribe Pargaini. Figs 47–51. Tribe Pargaini, male Odontomeluskwidschwianus: 47. Lateral aspect head from left side showing foveolus; 48. Dorsal aspect anterior left femur; 49. Lateral aspect left hind knee (outer side); 50. Oblique aspect of abdominal apex; 51. Dorsal and lateral aspect (from left side) epiphallus. Figs 52–56. Tribe Phlaeobini, Afrophlaeoba genus group, Paralobopomaviridifrons male: 52. Lateral aspect head from left side showing absence of lateral foveolus; 53. Dorsal aspect anterior left femur; 54. Lateral aspect left hind knee (outer side); 55. Oblique aspect of abdominal apex; 56. Dorsal and lateral aspect (from left side) epiphallus. Figs 57–59.Afrophlaeoba genus group, male abdominal apices: 57.Afrophlaeobausambarica; 58.Chokweaeucteanacomb. n.; 59.Platyverticularitchiei. 59A. P.ritchiei female abdominal apices obliquely from above and from below. Figs 60–61. Male frontal ridge: 60.Parodontomelusbrachypterus; 61.Parodontomelusmazumbaiensis. Figs 62–63. Male fastigium verticis from above: 62.Parodontomelusstoltzeicomb. n.; 63.Parodontomelusverticulus. All scale lines represent l mm: that under Fig. 47 applies to Figs 48–50, 52 and 55; that under Fig. 51 applies to Fig. 56; that under Fig. 57 applies to 58 and 59; that under Figs 60 to 61 also; that under Fig. 59A to both figs; that under Fig. 62 to Fig. 63
Herne Bay 1830-1880 a failed seaside resort?
No full textThis thesis sets out to examine Herne Bay’s success or otherwise as a seaside resort in the period during the nineteenth century, with a specific focus on the period from 1830 until around 1880. The significance of these dates centres upon the involvement of speculators and the building of the first deep sea pier that opened in 1832 closely followed by the passing of an Improvement Act in 1833. The effect of the 1833 Act was to provide a form of governance over the town’s affairs with varying effectiveness until this was reformed in the early 1880s as a result of provisions contained within the Public Health Act 1875. This time period also includes important transport developments that had a significant effect upon the town
A revision of the grasshopper genus Orthochtha and its allies (Orthoptera: Acrididae: Acridinae)
No full textThis revision concerns the genera Orthochtha, Euprepoptera, Lobopoma, Pamacris and Xerophlaeoba, which are diagnosed and redescribed, plus three others erected here: Shabacris for Lobopoma robusta, Nimbacris for Lobopoma longicornis and Xenocymochtha for a new species, barkeri, here described. As now recognized, Orthochtha comprises 25 species and 11 subspecies of which 12 species and five subspecies respectively are described here as new, while the identity of another species, O. angustata, remains uncertain. Of the other genera, two species are now recognized within Euprepoptera, one of which is new, three within Lobopoma (two new) and two within Pamacris, with carterocera transferred from Lobopoma. In all, 36 species and 11 subspecies are diagnosed, illustrated, keyed and their distributions mapped. Six new synonymies are established and four specific names recalled but given new status as subspecies; two other species are reduced to the rank of subspecies. Six lectotypes and one neotype are designated. The affinities of the taxa are discussed on the basis of classical taxonomic criteria and also by numerical analysis. Their biogeographies are assessed, notably in terms of the postulated environmental influences on their evolution. A synopsis of the available information on the biology, ecology and economic importance is given for each species
Recent progress in L-H transition studies at JET: Tritium, Helium, Hydrogen and Deuterium
No full textWe present an overview of results from a series of L-II transition experiments undertaken at JET since the installation of the ITER-like-wall (JET-ILW), with beryllium wall tiles and a tungsten divertor. Tritium, helium and deuterium plasmas have been investigated. Initial results in tritium show ohmic L-H transitions at low density and the power threshold for the L-H transition (P-LH) is lower in tritium plasmas than in deuterium ones at low densities, while we still lack contrasted data to provide a scaling at high densities. In helium plasmas there is a notable shift of the density at which the power threshold is minimum ((n) over bar (e,min)) to higher values relative to deuterium and hydrogen references. Above (n) over bar (e,min) (He) the L-H power threshold at high densities is similar for D and He plasmas. Transport modelling in slab geometry shows that in helium neoclassical transport competes with interchange-driven transport, unlike in hydrogen isotopes. Measurements of the radial electric field in deuterium plasmas show that E-r shear is not a good indicator of proximity to the L-H transition. Transport analysis of ion heat flux in deuterium plasmas show a non-linearity as density is decreased below (n) over bar (e,min). Lastly, a regression of the JET-ILW deuterium data is compared to the 2008 ITPA scaling law
Bird species richness and diversity at montane Important Bird Area (IBA) sites in south-eastern Nigeria
No full textThe mountains of south-eastern Nigeria are a western extension of the Cameroon mountain range, which is classified as an endemic bird area (EBA). Unlike its eastern extension in Cameroon, most of the ornithological surveys in the western extension of the Cameroon highlands in Nigeria have produced only limited checklists and inventories. There is a clear need for quantitative baseline data so that conservation problems can be identified. Twenty line transects covering a total transect length of 28.8 km were used to survey five sites (Afi Mountain Wildlife Sanctuary, Oban and Okwangwo Division of Cross River National Park, Sankwala Mountains and Mbe Mountains) in the westernmost extension of the Cameroon Mountains EBA in south western Nigeria. Vegetation measurements were taken to control for the potential confounding effect of variation in vegetation density and structure on detectability of birds between sites. The 193 bird species recorded in Afi, 158 in Sankwala, 124 in Oban, 100 in Mbe and 73 in Okwangwo Division included most of the Cameroon highlands restricted range species. The results show that the mountains of south-eastern Nigeria are important parts of the Cameroon EBA, particularly the Afi Mountain Wildlife Sanctuary. However these sites are threatened by fire and livestock grazing on the hilltops, shifting agriculture on the hillsides and lowlands, and logging for timber in some parts, as well as wildlife hunting for bush meat.Peer reviewe
JET machine operations in T&D-T
No full textJET, the world's largest operating tokamak with unique Be/W wall and tritium handling capability, completed a Deuterium-Tritium (D-T) campaign in 2021 (Maggi et al 29th Fusion Energy Conf.) following a decade of preparatory experiments, dedicated enhancements, technical rehearsals and training (Horton et al 2016 Fusion Eng. Des. 109-111 925). Operation with tritium raises significant technical, safety and scientific challenges not encountered in standard protium or deuterium operation. This contribution describes the tritium operational requirements, pulses and technical preparations, new operating procedures, lessons learned and details on the achieved operational availability and performance. The preparation and execution of the recent JET tritium experiments benefitted from the previous experience in 1991 (Preliminary Tritium Experiment), 1997 (DTE1 campaign) and 2003 (Trace Tritium Campaigns) and consisted of the following five phases: technical rehearsals and scenario preparation, tritium commissioning, 100% tritium campaign, D-T campaign (DTE2), tritium clean-up. Following the clean-up JET resumed normal operation and is currently undertaking a further D-T campaign (DTE3)
Impurity study in the dimensionless and dimensional isotope identity experiment between JET Deuterium and Tritium L-mode plasmas
No full textThe behaviour of impurities in fusion plasmas is of crucial importance for achieving sustained fusion reactions, and understanding similarities and differences between Deuterium (D) and Tritium (T) plasmas is needed to assess potential changes from DD to DT in ITER and future reactors. The first dimensionless and dimensional isotope identity experiments between Deuterium (D) and Tritium (T) L-mode plasmas were conducted at the JET W/Be wall. In the first approach, the discharges with matched ρ∗, ν∗, βn, q, and Te/Ti were compared to emphasize direct isotope effects, while in the dimensional approach engineering parameters such as toroidal magnetic field BT, plasma current Ip, plasma electron density and NBI power PNBI were matched. The dimensionless isotope scaling showed an improvement in global confinement and local transport in T plasmas in comparison to the matched D one (Cordey et al 1999 Nucl. Fusion 39 301). Detailed impurity analyses using VUV, visible spectroscopy, SXR cameras, and bolometry revealed that T plasmas exhibited higher radiation and impurity content, particularly Ni and W, compared to D plasmas. Understanding the origin of the increased impurity content is addressed in this paper. The dimensionless experiments showed differences in impurity transport. The Be source behaviour varied: D plasmas had higher Be influx in the dimensionless approach due to lower electron density and enhanced sputtering (Saibene et al 1999 Nucl. Fusion 39 1133), while T plasmas showed a higher Be source in the dimensional experiments, highlighting isotope mass effects. W in the divertor region was not sputtered by hydrogen isotopes. W in the divertor region was not sputtered by hydrogen isotopes. In the dimensionless experiments, W sputtering was primarily influenced by Ni in T plasmas and by Be in D plasmas. However, in the dimensional approach, Be played a more significant role in W sputtering within T plasmas. MHD instabilities, including ST oscillations, were present in all cases other ones were correlated with NBI power levels; higher NBI power led to elevated levels of Be, Ni, and W impurities. The comprehensive comparison underscores the necessity of accounting for isotope mass effects in predictive modelling and optimization of plasma performance in fusion reactors
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