117 research outputs found
Generalised supersymmetry and p-brane actions
We investigate the most general N=1 graded extension of the Poincare algebra,
and find the corresponding supersymmetry transformations and the associated
superspaces. We find that the supersymmetry for which {Q,Q} = P is not special,
and in fact must be treated democratically with a whole class of
supersymmetries. We show that there are two distinct types of grading, and a
new class of general spinors is defined. The associated superspaces are shown
to be either of the usual type, or flat with no torsion. p-branes are discussed
in these general superspaces and twelve dimensions emerges as maximal. New
types of brane are discovered which could explain many features of the standard
p-brane theories.Comment: 29 pages, LaTex, no figures. Errors in degrees of freedom counting
corrected, leading to altered brane sca
Exact non-abelian duality
We investigate non-abelian gaugings of WZNW models. When the gauged group is
semisimple we are able to present exact formulae for the dual conformal field
theory, for all values of the level . The results are then applied to
non-abelian target space duality in string theory, showing that the standard
formulae are quantum mechanically well defined in the low energy limit if the
gauged group is semisimple.Comment: 17 pages uuencoded Z-compressed late
Revisiting the crime scene: Intermedial translation, adaptation and novelization of The Killing
Spatial variation in spring arrival patterns of AfroâPalaearctic bird migration across Europe
Aim: Geographical patterns of migrant species arrival have been little studied, despite their relevance to global change responses. Here, we quantify continent-wide inter-specific variation in spatio-temporal patterns of spring arrival of 30 common migrant bird species and relate these to species characteristics and environmental conditions.Location: EuropeTime period: 2010-2019Major taxa studied: Birds, 30 speciesMethods: Using citizen science data from EuroBirdPortal, we modelled arrival phenology for 30 Afro-Palearctic migrant species across Europe to extract start and duration of species arrival at a 400 km square resolution. We related inter and intra-specific variation in arrival and duration to species characteristics and temperature at the start of the growing season (green-up) .Results: Spatial variation in start of arrival times indicates it took on average 1.6 days for the leading migratory front to move northwards by 100 km (range: 0.6â2.5 days). There was a major gradient in arrival phenology, from species which arrived earlier, least synchronously, in colder temperatures and progressed slowly northwards to species which arrived later, most synchronously and in warmer temperatures, and advanced quickly through Europe. The slow progress of early arrivers suggests that temperature limits their northward advance; this group included Aerial Insectivores and species wintering north of the Sahel. For the late arrivers, which included species wintering further south, seasonal resource availability in Africa may delay their arrival into Europe.Main conclusions: We found support for the green-wave hypothesis applying widely to migratory landbirds. Species arrival phenologies are linked to ecological differences between taxa, such as diet, and wintering location. Understanding these differences informs predictions of speciesâ sensitivity to global change. Publishing these arrival phenologies will facilitate further research and have additional conservation benefits such as informing designation of hunting seasons. Our methods are applicable to any taxa with repeated occurrence data across large scales. Key words: phenology, European-African migrants, bird migration, spring arrival, spatial variation, intraspecific and interspecific variation, EuroBirdPortal, citizen scientists, complete lists and casual record
Diatremes act as fluid conduits for Zn-Pb mineralization in the SW Irish Ore field
Irish-type mineralization is commonly attributed to fault-controlled mixing of a seawater-derived, sulfur-rich fluid and basement-derived, metal-rich fluid. However, maar-diatreme volcanoes discovered in close spatial and temporal association with Zn-Pb mineralization at Stonepark in the Limerick basin (southwest Ireland) bring a new dimension to established geologic models and may increase the deposit-scale prospectivity in one of the worldâs greatest Zn-Pb districts. Stonepark exhibits many incidences of dolomitic black matrix breccias with associated Zn-Pb mineralization, the latter typically occurring within 150 m of the diatremes. Highly negative ÎŽ34S pyrite values within country rock-dominated black matrix breccias (â12 to â34â°) are consistent with sulfide precipitation from bacteriogenic sulfur reduction in seawater-derived brines. However, ÎŽ34S values of Zn-Pb sulfides replacing black matrix breccias (â10 to 1â°) reflect multiple sulfur sources. Diatreme emplacement both greatly enhanced country rock fracture permeability and produced conduits that are filled with porous volcaniclastic material and extend down to basement rock types. Our ÎŽ34S data suggest that diatremes provide more efficient fluid pathways for basement-derived fluids. The diatremes introduce another potential sulfur source and facilitate a greater input of metal-rich basement-derived hydrothermal fluid into the system compared to other Irish-type deposits such as Navan and Lisheen, evidenced by Stoneparkâs more positive modal ÎŽ34S value of â4â°. Irish-type deposits are traditionally thought to form in association with extensional basement faults and are considered unrelated to extensive Carboniferous magmatism. Our results indicate that a direct link exists between diatreme volcanism and Zn-Pb mineralization at Limerick, prompting a reevaluation of the traditional Irish-type ore formation model, in regions where mineralization is spatially associated with volcanic pipes.Natural Environment Research Council (IP-1397-1113); SUERC; Teck Ireland Ltd
The twelve dimensional super (2+2)-brane
We discuss supersymmetry in twelve dimensions and present a covariant
supersymmetric action for a brane with worldsheet signature (2,2), called a
super (2+2)-brane, propagating in the osp(64,12) superspace. This superspace is
explicitly constructed, and is trivial in the sense that the spinorial part is
a trivial bundle over spacetime, unlike the twisted superspace of usual
Poincare supersymmetry. For consistency, it is necessary to take a projection
of the superspace. This is the same as the projection required for worldvolume
supersymmetry. Upon compactification of this superspace, a torsion is naturally
introduced and we produce the membrane and type IIB string actions in 11 and 10
dimensional Minkowski spacetimes. In addition, the compactification of the
twelve dimensional supersymmetry algebra produces the correct algebras for
these theories, including central charges. These considerations thus give the
type IIB string and M-theory a single twelve dimensional origin.Comment: 32 pages LaTex, no figures, minor comments and address(!) adde
Hantavirus infection in type I interferon receptor-deficient (A129) mice.
Type I interferon receptor knockout mice (strain A129) were assessed as a disease model of hantavirus infection. A range of infection routes (intramuscular, intraperitoneal and intranasal) were assessed using minimally passaged Seoul virus (strain Humber). Dissemination of virus to the spleen, kidney and lung was observed at 5âdays after intramuscular and intraperitoneal challenge, which was resolved by day 14. In contrast, intranasal challenge of A129 mice demonstrated virus tropism to the lung, which was maintained to day 14 post-challenge. These data support the use of the A129 mouse model for future infection studies and the in vivo evaluation of interventions
Towards quantification of protective antibody responses by passive transfer of the 1st WHO International Standard for Ebola virus antibody in a guinea pig model.
Ebola virus (EBOV) represents a major concern to global health due to the unpredictable nature of outbreaks. Infection with EBOV can cause a severe viral haemorrhagic fever with no licensed vaccine or treatment, restricting work with live EBOV to Containment/Biosafety Level 4 facilities. Whilst the magnitude of recent outbreaks has provided an impetus for vaccine and antiviral development, establishing the efficacy of candidate vaccine materials relies on EBOV challenge models and advanced human trials should outbreaks occur and where logistics and funding allow. To address these hurdles in vaccine development, we investigated whether a recently established serological reference standard, the 1st WHO International Standard for Ebola virus antibody, could be used to provide a quantifiable correlate of immune protection in vivo. Dilutions of the International Standard were inoculated into naĂŻve guinea pigs 24âŻh before challenge with a lethal dose of Ebola virus. Only subjects receiving the highest dose of the International Standard exhibited evidence of delayed progression. Due to it being a WHO established reagent and available globally upon request, this standard allows for effective comparisons of data between laboratories and may prove valuable to select the candidate vaccines that are most likely to confer humoral immune protection ensuring the most promising candidates progress into efficacy studies
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