The Vector-Tensor Supermultiplet with Gauged Central Charge

The vector-tensor multiplet is coupled off-shell to an N=2 vector multiplet such that its central charge transformations are realized locally. A gauged central charge is a necessary prerequisite for a coupling to supergravity and the strategy underlying our construction uses the potential for such a coupling as a guiding principle. The results for the action and transformation rules take a nonlinear form and necessarily include a Chern-Simons term. After a duality transformation the action is encoded in a homogeneous holomorphic function consistent with special geometry.Comment: 8 pages, LATE

N=2 Conformal Superspace in Four Dimensions

We develop the geometry of four dimensional N=2 superspace where the entire conformal algebra of SU(2,2|2) is realized linearly in the structure group rather than just the SL(2,C) x U(2)_R subgroup of Lorentz and R-symmetries, extending to N=2 our prior result for N=1 superspace. This formulation explicitly lifts to superspace the existing methods of the N=2 superconformal tensor calculus; at the same time the geometry, when degauged to SL(2,C) x U(2)_R, reproduces the existing formulation of N=2 conformal supergravity constructed by Howe.Comment: 43 pages; v2 references added, acknowledgments update

A New Supersymmetric Compactification of Chiral IIB Supergravity

We present a new compactification of chiral, N=2 ten-dimensional supergravity down to five dimensions and show that it corresponds to the N=2 supersymmetric critical point of five-dimensional, N=8 gauged supergravity found in [KPW]. This solution presented here is of particular significance because it involves non-zero tensor gauge fields and, via the AdS/CFT correspondence, is dual to the non-trivial N=1 supersymmetric fixed point of N=4 Yang-Mills theory.Comment: 14 pages, references added, some typos correcte

On The spectrum of a Noncommutative Formulation of the D=11 Supermembrane with Winding

A regularized model of the double compactified D=11 supermembrane with nontrivial winding in terms of SU(N) valued maps is obtained. The condition of nontrivial winding is described in terms of a nontrivial line bundle introduced in the formulation of the compactified supermembrane. The multivalued geometrical objects of the model related to the nontrivial wrapping are described in terms of a SU(N) geometrical object which in the $N\to \infty$ limit, converges to the symplectic connection related to the area preserving diffeomorphisms of the recently obtained non-commutative description of the compactified D=11 supermembrane.(I. Martin, J.Ovalle, A. Restuccia. 2000,2001) The SU(N) regularized canonical lagrangian is explicitly obtained. In the $N\to \infty$ limit it converges to the lagrangian in (I.Martin, J.Ovalle, A.Restuccia. 2000,2001) subject to the nontrivial winding condition. The spectrum of the hamiltonian of the double compactified D=11 supermembrane is discussed. Generically, it contains local string like spikes with zero energy. However the sector of the theory corresponding to a principle bundle characterized by the winding number $n \neq 0$, described by the SU(N) model we propose, is shown to have no local string-like spikes and hence the spectrum of this sector should be discrete.Comment: 16 pages.Latex2

Reaction diffusion processes on random and scale-free networks

We study the discrete Gierer-Meinhardt model of reaction-diffusion on three different types of networks: regular, random and scale-free. The model dynamics lead to the formation of stationary Turing patterns in the steady state in certain parameter regions. Some general features of the patterns are studied through numerical simulation. The results for the random and scale-free networks show a marked difference from those in the case of the regular network. The difference may be ascribed to the small world character of the first two types of networks.Comment: 8 pages, 7 figure

Bistable Gestalts reduce activity in the whole of V1, not just the retinotopically predicted parts

Activity in the primary visual cortex reduces when certain stimuli can be perceptually organized as a unified Gestalt. This reduction could offer important insights into the nature of feedback computations within the human visual system; however, the properties of this response reduction have not yet been investigated in detail. Here we replicate this reduced V1 response, but find that the modulation in V1 (and V2) to the perceived organization of the input is not specific to the retinotopic location at which the sensory input from that stimulus is represented. Instead, we find a response modulation that is equally evident across the primary visual cortex. Thus in contradiction to some models of hierarchical predictive coding, the perception of an organized Gestalt causes a broad feedback effect that does not act specifically on the part of the retinotopic map representing the sensory input

Christ-centred ethical behaviour and ecological crisis: What resources do the concepts of order in creation and eschatological hope offer?

The ecological crisis, as well as a limited ethical response, forces a reflection on the transformative potential of Christian ethics on an idolatrous society largely shaped by a dominant economic culture. The aim of the article was to explore how the concepts of creation order and eschatological hope may be helpful in the understanding and formulation of a Christ-centred ethical response to the ecological crisis. A review of the relevant literature was presented, limited to insights from Reformational philosophy and eco-theology into the concepts of creation order and eschatology. The main internal tensions of using the concepts of creation order and eschatological hope as resources in Christ-centred eco-ethics were highlighted and discussed. Some implications for the further explanation and development of Christ-centred eco-ethics are outlined.Christosentriese etiese gedrag en ekologiese krisis: Watter hulpbronne bied die konsepte van orde in die skepping en eskatologiese hoop? Die ekologiese krisis, asook ’n beperkte etiese antwoord hierop, dwing ’n besinning oor die vernuwende potensiaal van Christelike etiek vir ’n afgodiese samelewing wat grootliks gevorm is deur ’n dominante ekonomiese kultuur. Die doel van hierdie artikel was om te ondersoek hoe die konsepte van orde in die skepping en eskatologiese hoop nuttig kan wees in die verstaan en die formulering van ’n Christus- gesentreerde etiese antwoord op die ekologiese krisis. ’n Oorsig van die relevante literatuur, beperk tot insigte uit die Reformatoriese filosofie en ekoteologie oor die konsepte van orde in die skepping en eskatologie, is aangebied. Die belangrikste interne spanningsvelde in die gebruik van die konsepte skeppingsorde en eskatologiese hoop in ’n Christus-gesentreerde eko-etiek is uitgelig en bespreek. Sekere implikasies vir die verdere verduideliking en die ontwikkeling van ’n Christus-gesentreerde eko-etiek is beskryf

Wild ruminants as reservoirs of domestic livestock gastrointestinal T nematodes

Gastrointestinal nematode (GIN) infections in cattle cause appetite suppression which leads to poor feed conversion, reduced weight gain and reduced milk production. Overuse and exclusive reliance on anthelmintic drugs has resulted in widespread resistance in many parasitic nematode species infecting livestock making control increasingly difficult. Wild ruminants are competent hosts of a number of nematode species that typically infect and are best adapted for cattle, sheep, and goats. Thus, the potential exists for wild ruminants to act as reservoirs in the translocation of domestic GIN, including those carrying anthelmintic resistance mutations as well as susceptible genotypes. The potential for parasite exchange is heightened by interfaces or ecotones between managed and wild rangelands, and by perturbations linked to climate warming that can increasingly alter the distributions of wild ungulates and their interactions with domestic and free-ranging ruminants. To investigate the extent to which wild ruminants harbour parasites capable of infecting domestic ruminants we first performed an epidemiological study of feces from wildlife hosts that spanned 16 states and included white-tailed deer (85 % of the samples), pronghorn, elk, mule deer, bighorn sheep, moose, cattle, and caribou across the United States. All samples were cultured to third stage larvae and nematode DNA was isolated and PCR amplified. Among the 548 wild ruminant samples received, 33 % (181 samples) were positive for nematode DNA, among which half (84 samples) contained DNA from GIN species commonly found in cattle. DNA from cattle GIN species was detected in 46 % of samples from the Northeast, 42 % from the Southeast, 10 % from the Midwest, 0 % from the Southwest and 11 % from the West. Deep amplicon sequencing of the ITS-2 rDNA indicated that Ostertagia and Trichostrongylus were present in 90 % and 69 % of the nematode DNA positive samples, respectively, whereas Haemonchus, Cooperia and Oesophagostomum were present in 26 %, 2 % and 10 % of the samples, respectively. These data clearly show that wild ruminants commonly harbour multiple parasite species whose primary hosts are domestic cattle, and suggest that further work is warranted to investigate their specific roles in the management of anthelmintic resistance