3,292 research outputs found
Development of a species-specific coproantigen ELISA for human taenia solium taeniasis
Taenia solium causes human neurocysticercosis and is endemic in underdeveloped countries where backyard pig keeping is common. Microscopic fecal diagnostic methods for human T. solium taeniasis are not very sensitive, and Taenia saginata and Taenia solium eggs are indistinguishable under the light microscope. Coproantigen (CoAg) ELISA methods are very sensitive, but currently only genus (Taenia) specific. This paper describes the development of a highly species-specific coproantigen ELISA test to detect T. solium intestinal taeniasis. Sensitivity was maintained using a capture antibody of rabbit IgG against T. solium adult whole worm somatic extract, whereas species specificity was achieved by utilization of an enzyme-conjugated rabbit IgG against T. solium adult excretory-secretory (ES) antigen. A known panel of positive and negative human fecal samples was tested with this hybrid sandwich ELISA. The ELISA test gave 100% specificity and 96.4% sensitivity for T. solium tapeworm carriers (N = 28), with a J index of 0.96. This simple ELISA incorporating anti-adult somatic and anti-adult ES antibodies provides the first potentially species-specific coproantigen test for human T. solium taeniasis
Six-dimensional Supergravity and Projective Superfields
We propose a superspace formulation of N=(1,0) conformal supergravity in six
dimensions. The corresponding superspace constraints are invariant under
super-Weyl transformations generated by a real scalar parameter. The known
variant Weyl super-multiplet is recovered by coupling the geometry to a
super-3-form tensor multiplet. Isotwistor variables are introduced and used to
define projective superfields. We formulate a locally supersymmetric and
super-Weyl invariant action principle in projective superspace. Some families
of dynamical supergravity-matter systems are presented.Comment: 39 pages; v3: some modifications in section 2; equations (2.3),
(2.14b), (2.16) and (2.17) correcte
Off-shell supergravity-matter couplings in three dimensions
We develop the superspace geometry of N-extended conformal supergravity in
three space-time dimensions. General off-shell supergravity-matter couplings
are constructed in the cases N=1,2,3,4.Comment: 73 pages; V5: typos in eqs. (3.4b), (3.17) and (4.24) correcte
From correlation functions to scattering amplitudes
We study the correlators of half-BPS protected operators in N=4
super-Yang-Mills theory, in the limit where the positions of the adjacent
operators become light-like separated. We compute the loop corrections by means
of Lagrangian insertions. The divergences resulting from the light-cone limit
are regularized by changing the dimension of the integration measure over the
insertion points. Switching from coordinates to dual momenta, we show that the
logarithm of the correlator is identical with twice the logarithm of the
matching MHV gluon scattering amplitude. We present a number of examples of
this new relation, at one and two loops.Comment: typos corrected, references adde
Estimating bank default with generalised extreme value regression models
The paper proposes a novel model for the prediction of bank failures, on the basis of both macroeconomic and bank-specific microeconomic factors. As bank failures are rare, in the paper we apply a regression method for binary data based on extreme value theory, which turns out to be more effective than classical logistic regression models, as it better leverages the information in the tail of the default distribution. The application of this model to the occurrence of bank defaults in a highly bank dependent economy (Italy) shows that, while microeconomic factors as well as regulatory capital are significant to explain proper failures, macroeconomic factors are relevant only when failures are defined not only in terms of actual defaults but also in terms of mergers and acquisitions. In terms of predictive accuracy, the model based on extreme value theory outperforms classical logistic regression models
From correlation functions to Wilson loops
We start with an n-point correlation function in a conformal gauge theory. We
show that a special limit produces a polygonal Wilson loop with sides. The
limit takes the points towards the vertices of a null polygonal Wilson loop
such that successive distances . This produces a fast moving
particle that generates a "frame" for the Wilson loop. We explain in detail how
the limit is approached, including some subtle effects from the propagation of
a fast moving particle in the full interacting theory. We perform perturbative
checks by doing explicit computations in N=4 super-Yang-Mills.Comment: 37 pages, 10 figures; typos corrected, references adde
A realistic pattern of fermion masses from a five-dimensional SO(10) model
We provide a unified description of fermion masses and mixing angles in the
framework of a supersymmetric grand unified SO(10) model with anarchic Yukawa
couplings of order unity. The space-time is five dimensional and the extra flat
spatial dimension is compactified on the orbifold ,
leading to Pati-Salam gauge symmetry on the boundary where Yukawa interactions
are localised. The gauge symmetry breaking is completed by means of a rather
economic scalar sector, avoiding the doublet-triplet splitting problem. The
matter fields live in the bulk and their massless modes get exponential
profiles, which naturally explain the mass hierarchy of the different fermion
generations. Quarks and leptons properties are naturally reproduced by a
mechanism, first proposed by Kitano and Li, that lifts the SO(10) degeneracy of
bulk masses in terms of a single parameter. The model provides a realistic
pattern of fermion masses and mixing angles for large values of . It
favours normally ordered neutrino mass spectrum with the lightest neutrino mass
below 0.01 eV and no preference for leptonic CP violating phases. The right
handed neutrino mass spectrum is very hierarchical and does not allow for
thermal leptogenesis. We analyse several variants of the basic framework and
find that the results concerning the fermion spectrum are remarkably stable.Comment: 30 pages, 7 figures, 4 table
Persistence of anticancer activity in berry extracts after simulated gastrointestinal digestion and colonic fermentation
Fruit and vegetable consumption is associated at the population level with a protective effect against colorectal cancer. Phenolic compounds, especially abundant in berries, are of interest due to their putative anticancer activity. After consumption, however, phenolic compounds are subject to digestive conditions within the gastrointestinal tract that alter their structures and potentially their function. However, the majority of phenolic compounds are not efficiently absorbed in the small intestine and a substantial portion pass into the colon. We characterized berry extracts (raspberries, strawberries, blackcurrants) produced by in vitro-simulated upper intestinal tract digestion and subsequent fecal fermentation. These extracts and selected individual colonic metabolites were then evaluated for their putative anticancer activities using in vitro models of colorectal cancer, representing the key stages of initiation, promotion and invasion. Over a physiologically-relevant dose range (0–50 µg/ml gallic acid equivalents), the digested and fermented extracts demonstrated significant anti-genotoxic, anti-mutagenic and anti-invasive activity on colonocytes. This work indicates that phenolic compounds from berries undergo considerable structural modifications during their passage through the gastrointestinal tract but their breakdown products and metabolites retain biological activity and can modulate cellular processes associated with colon cancer
Exploring novel correlations in trilepton channels at the LHC for the minimal supersymmetric inverse seesaw model
We investigate signatures of the minimal supersymmetric inverse seesaw model
at the large hadron collider (LHC) with three isolated leptons and large
missing energy (3\ell + \mET or 2\ell + 1\tau + \mET, with \ell=e,\mu) in the
final state. This signal has its origin in the decay of chargino-neutralino
(\chpm1\ntrl2) pair, produced in pp collisions. The two body decays of the
lighter chargino into a charged lepton and a singlet sneutrino has a
characteristic decay pattern which is correlated with the observed large
atmospheric neutrino mixing angle. This correlation is potentially observable
at the LHC by looking at the ratios of cross sections of the trilepton + \mET
channels in certain flavour specific modes. We show that even after considering
possible leading standard model backgrounds these final states can lead to
reasonable discovery significance at the LHC with both 7 TeV and 14 TeV
center-of-mass energy.Comment: 28 pages, 9 .eps figures. 3 new figures and discussions on LHC
observables added, minor modifications in text and in the abstract, 23 new
references added, matches with the published version in JHE
Off-shell superconformal nonlinear sigma-models in three dimensions
We develop superspace techniques to construct general off-shell N=1,2,3,4
superconformal sigma-models in three space-time dimensions. The most general
N=3 and N=4 superconformal sigma-models are constructed in terms of N=2 chiral
superfields. Several superspace proofs of the folklore statement that N=3
supersymmetry implies N=4 are presented both in the on-shell and off-shell
settings. We also elaborate on (super)twistor realisations for (super)manifolds
on which the three-dimensional N-extended superconformal groups act
transitively and which include Minkowski space as a subspace.Comment: 67 pages; V2: typos corrected, one reference added, version to appear
on JHE
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