938 research outputs found
Pneumococcal Induced T-activation with Resultant Thrombotic Microangiopathy
Thrombotic microangiopathies are disorders resulting from platelet thromboses forming in the microvasculature with resultant schistocyte forms. Hemolytic uremic syndrome (HUS) is a microangiopathic hemolytic anemia often complicated by acute renal failure in children. HUS is typically caused by bacterial infection, most commonly enterohemorrhagic Escherichia coli. Neuraminidase-producing organisms, such as Streptococcus pneumoniae have also been reported as potential etiologies. The pathogenesis in these cases involves cleavage of sialic acid residues from the surfaces of erythrocytes, platelets, and glomerular capillary endothelial cells, exposing the Thomsen-Friedenreich antigen, a process known as T-activation. We describe a 2-year-old girl who presented with pneumococcal pneumonia and sepsis ultimately resulting in a thrombotic microangiopathy with acute renal failure, most consistent with HUS. The patientâs direct antiglobulin test was positive. Polyagglutination was observed with human adult serum, but not with umbilical cord serum. Her red blood cells (RBCs) were reactive against peanut and soybean lectins, but not Salvia sclarea or Salvia horminum lectins. These findings are consistent with T-activation. Clinicians should be cognizant of the possibility of T-activation with resultant HUS in patients infected with neuraminidase-producing bacteria. Such patients may be difficult to identify using monoclonal typing antisera, as these typically do not have anti-T antibodies. Whether such patients are at risk for transfusion-associated hemolysis is debatable
Regularisation Techniques for the Radiative Corrections of Wilson lines and Kaluza-Klein states
Within an effective field theory framework we compute the most general
structure of the one-loop corrections to the 4D gauge couplings in one- and
two-dimensional orbifold compactifications with non-vanishing constant gauge
background (Wilson lines). Although such models are non-renormalisable, we keep
the analysis general by considering the one-loop corrections in three
regularisation schemes: dimensional regularisation (DR), Zeta-function
regularisation (ZR) and proper-time cut-off regularisation (PT). The relations
among the results obtained in these schemes are carefully addressed. With
minimal re-definitions of the parameters involved, the results obtained for the
radiative corrections can be applied to most orbifold compactifications with
one or two compact dimensions. The link with string theory is discussed. We
mention a possible implication for the gauge couplings unification in such
models.Comment: 37 pages, 1 Figure, LaTeX; minor correction
Predicting microbial water quality with models: Over-arching questions for managing risk in agricultural catchments
The application of models to predict concentrations of faecal indicator organisms (FIOs) in environmental systems plays an important role for guiding decision-making associated with the management of microbial water quality. In recent years there has been an increasing demand by policy-makers for models to help inform FIO dynamics in order to prioritise efforts for environmental and human-health protection. However, given the limited evidence-base on which FIO models are built relative to other agricultural pollutants (e.g. nutrients) it is imperative that the end-user expectations of FIO models are appropriately managed. In response, this commentary highlights four over-arching questions associated with: (i) model purpose; (ii) modelling approach; (iii) data availability; and (iv) model application, that must be considered as part of good practice prior to the deployment of any modelling approach to predict FIO behaviour in catchment systems. A series of short and longer-term research priorities are proposed in response to these questions in order to promote better model deployment in the field of catchment microbial dynamics
Living with Ghosts and their Radiative Corrections
The role of higher derivative operators in 4D effective field theories is
discussed in both non-supersymmetric and supersymmetric contexts. The approach,
formulated in the Minkowski space-time, shows that theories with higher
derivative operators do not always have an improved UV behaviour, due to
subtleties related to the analytical continuation from the Minkowski to the
Euclidean metric. This continuation is further affected at the dynamical level
due to a field-dependence of the poles of the Green functions of the
particle-like states, for curvatures of the potential of order unity in ghost
mass units. The one-loop scalar potential in lambda*phi^4 theory with a single
higher derivative term is shown to have infinitely many counterterms, while for
a very large mass of the ghost the usual 4D renormalisation is recovered. In
the supersymmetric context of the O'Raifeartaigh model of spontaneous
supersymmetry breaking with a higher derivative (supersymmetric) operator, it
is found that quadratic divergences are present in the one-loop self-energy of
the scalar field. They arise with a coefficient proportional to the amount of
supersymmetry breaking and suppressed by the scale of the higher derivative
operator. This is also true in the Wess-Zumino model with higher derivatives
and explicit soft breaking of supersymmetry. In both models, the UV logarithmic
behaviour is restored in the decoupling limit of the ghost.Comment: 28 pages, 3 figures; added reference
Defect Conformal Field Theory and Locally Localized Gravity
Gravity may be "locally localized" over a wide range of length scales on a
d-dimensional anti-de Sitter (AdS) brane living inside AdS_{d+1}. In this paper
we examine this phenomenon from the point of view of the holographic dual
"defect conformal field theory". The mode expansion of bulk fields on the
gravity side is shown to be precisely dual to the "boundary operator product
expansion" of operators as they approach the defect. From the field theory
point of view, the condition for localization is that a "reduced operator"
appearing in this expansion acquires negative anomalous dimension. In
particular, a very light localized graviton exists when a mode arising from the
reduction of the ambient stress-energy tensor to the defect has conformal
dimension Delta ~ d-1. The part of the stress tensor containing the defect
dynamics has dimension Delta = d-1 in the free theory, but we argue that it
acquires an anomalous dimension in the interacting theory, and hence does not
participate in localization in the regime of small backreaction of the brane.
We demonstrate that such an anomalous dimension is consistent with the
conservation of the full stress-energy tensor. Finally, we analyze how to
compute the anomalous dimensions of reduced operators from gravity at leading
order in the interactions with the brane.Comment: 38 pages, LaTeX, 5 figures. v2: typos fixe
Holography and Defect Conformal Field Theories
We develop both the gravity and field theory sides of the Karch-Randall
conjecture that the near-horizon description of a certain D5-D3 brane
configuration in string theory, realized as AdS_5 x S^5 bisected by an AdS_4 x
S^2 "brane", is dual to N=4 Super Yang-Mills theory in R^4 coupled to an R^3
defect. We propose a complete Lagrangian for the field theory dual, a novel
"defect superconformal field theory" wherein a subset of the fields of N=4 SYM
interacts with a d=3 SU(N) fundamental hypermultiplet on the defect preserving
conformal invariance and 8 supercharges. The Kaluza-Klein reduction of wrapped
D5 modes on AdS_4 x S^2 leads to towers of short representations of OSp(4|4),
and we construct the map to a set of dual gauge-invariant defect operators O_3
possessing integer conformal dimensions. Gravity calculations of and
are given. Spacetime and N-dependence matches expectations from dCFT,
while the behavior as functions of lambda = g^2 N at strong and weak coupling
is generically different. We comment on a class of correlators for which a
non-renormalization theorem may still exist. Partial evidence for the
conformality of the quantum theory is given, including a complete argument for
the special case of a U(1) gauge group. Some weak coupling arguments which
illuminate the duality are presented.Comment: 47 pages, LaTeX, 2 figures, feynmf. v2: fixed minor errors, added
references. v3: fixed more typo
The average submillimetre properties of Lymanâα blobs at z = 3
Lyâα blobs (LABs) offer insight into the complex interface between galaxies and their circumgalactic medium. Whilst some LABs have been found to contain luminous star-forming galaxies and active galactic nuclei that could potentially power the Lyâα emission, others appear not to be associated with obvious luminous galaxy counterparts. It has been speculated that LABs may be powered by cold gas streaming on to a central galaxy, providing an opportunity to directly observe the âcold accretionâ mode of galaxy growth. Star-forming galaxies in LABs could be dust obscured and therefore detectable only at longer wavelengths. We stack deep Submillimetre Common User Bolometer Array 2 (SCUBA-2) observations of the Small Selected Area 22h field to determine the average 850 ÎŒm flux density of 34 LABs. We measure S850 = 0.6 ± 0.2 mJy for all LABs, but stacking the LABs by size indicates that only the largest third (area â„1794 kpc2) have a mean detection, at 4.5Ï, with S850 = 1.4 ± 0.3 mJy. Only two LABs (1 and 18) have individual SCUBA-2 >3.5Ï detections at a depth of 1.1 mJy beamâ1. We consider two possible mechanisms for powering the LABs and find that central star formation is likely to dominate the emission of Lyâα, with cold accretion playing a secondary role
Search for the Proton Decay Mode proton to neutrino K+ in Soudan 2
We have searched for the proton decay mode proton to neutrino K+ using the
one-kiloton Soudan 2 high resolution calorimeter. Contained events obtained
from a 3.56 kiloton-year fiducial exposure through June 1997 are examined for
occurrence of a visible K+ track which decays at rest into mu+ nu or pi+ pi0.
We found one candidate event consistent with background, yielding a limit,
tau/B > 4.3 10^{31} years at 90% CL with no background subtraction.Comment: 13 pages, Latex, 3 tables and 3 figures, Accepted by Physics Letters
Large-amplitude driving of a superconducting artificial atom: Interferometry, cooling, and amplitude spectroscopy
Superconducting persistent-current qubits are quantum-coherent artificial
atoms with multiple, tunable energy levels. In the presence of large-amplitude
harmonic excitation, the qubit state can be driven through one or more of the
constituent energy-level avoided crossings. The resulting
Landau-Zener-Stueckelberg (LZS) transitions mediate a rich array of
quantum-coherent phenomena. We review here three experimental works based on
LZS transitions: Mach-Zehnder-type interferometry between repeated LZS
transitions, microwave-induced cooling, and amplitude spectroscopy. These
experiments exhibit a remarkable agreement with theory, and are extensible to
other solid-state and atomic qubit modalities. We anticipate they will find
application to qubit state-preparation and control methods for quantum
information science and technology.Comment: 13 pages, 5 figure
Minimum information guideline for spectrophotometric and fluorometric methods to assess biofilm formation in microplates
Supplementary data to this article can be found online at https://doi.org/10.1016/j.bioflm.2019.100010.The lack of reproducibility of published studies is one of the major issues facing the scientific community, and the field of biofilm microbiology has been no exception. One effective strategy against this multifaceted problem is the use of minimum information guidelines. This strategy provides a guide for authors and reviewers on the necessary information that a manuscript should include for the experiments in a study to be clearly interpreted and independently reproduced. As a result of several discussions between international groups working in the area of biofilms, we present a guideline for the spectrophotometric and fluorometric assessment of biofilm formation in microplates. This guideline has been divided into 5 main sections, each presenting a comprehensive set of recommendations. The intention of the minimum information guideline is to improve the quality of scientific communication that will augment interlaboratory reproducibility in biofilm microplate assays.This project has received funding from the European Unionâs Horizon 2020 research and innovation program under the Marie Sklodowska â Curie grant agreement No 722467, as part of the Print-Aid consortium.
The information and views set out in this article are those of the authors and do not necessarily reflect the official opinion of the European Union. Neither the European Union institutions and bodies nor any person
acting on their behalf may be held responsible for the use which may be made of the information contained therein.
This work received additional financial support by: project UID/EQU/00511/2019 - Laboratory for Process Engineering, Environment, Biotechnology and Energy â LEPABE funded by national funds through
FCT/MCTES (PIDDAC); Project âLEPABE-2-ECO-INNOVATIONâ â NORTE-01-0145-FEDER-000005, funded by Norte Portugal Regional Operational Programme (NORTE 2020), under PORTUGAL 2020 Partnership Agreement, through the European Regional Development Fund (ERDF).info:eu-repo/semantics/publishedVersio
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