287 research outputs found
Covariant N=2 heterotic string in four dimensions
We construct a covariant formulation of the heterotic superstring on K3 times
T^2 with manifest N=2 supersymmetry. We show how projective superspace appears
naturally in the hybrid formulation giving a (partially) geometric
interpretation of the harmonic parameter. The low-energy effective action for
this theory is given by a non-standard form of N=2 supergravity which is
intimately related to the N=1 old-minimal formulation. This formalism can be
used to derive new descriptions of interacting projective superspace field
theories using Berkovits' open string field theory and the the heterotic
Berkovits-Okawa-Zwiebach construction.Comment: 11+3 page
Characterization of Open-Cell Sponges via Magnetic Resonance and X-ray Tomography
The applications of polymeric sponges are varied, ranging from cleaning and filtration to medical applications. The specific properties of polymeric foams, such as pore size and connectivity, are dependent on their constituent materials and production methods. Nuclear magnetic resonance imaging (MRI) and X-ray micro-computed tomography (mu CT) offer complementary information about the structure and properties of porous media. In this study, we employed MRI, in combination with mu CT, to characterize the structure of polymeric open-cell foam, and to determine how it changes upon compression, mu CT was used to identify the morphology of the pores within sponge plugs, extracted from polyurethane open-cell sponges. MRI T-2 relaxation maps and bulk T-2 relaxation times measurements were performed for 7 degrees dH water contained within the same polyurethane foams used for mu CT. Magnetic resonance and mu CT measurements were conducted on both uncompressed and 60% compressed sponge plugs. Compression was achieved using a graduated sample holder with plunger. A relationship between the average T-2 relaxation time and maximum opening was observed, where smaller maximum openings were found to have a shorter T-2 relaxation times. It was also found that upon compression, the average maximum opening of pores decreased. Average pore size ranges of 375-632 +/- 1 mu m, for uncompressed plugs, and 301-473 +/- 1 mu m, for compressed plugs, were observed. By determining maximum opening values and T-2 relaxation times, it was observed that the pore structure varies between sponges within the same production batch, as well as even with a single sponge
Instanton Calculations for N=1/ 2 super Yang-Mills Theory
We study (anti-) instantons in super Yang-Mills theories defined on a non
anticommutative superspace. The instanton solution that we consider is the same
as in ordinary SU(2) N=1 super Yang-Mills, but the anti-instanton receives
corrections to the U(1) part of the connection which depend quadratically on
fermionic coordinates, and linearly on the deformation parameter C. By
substituting the exact solution into the classical Lagrangian the topological
charge density receives a new contribution which is quadratic in C and quartic
in the fermionic zero-modes. The topological charge turns out to be zero. We
perform an expansion around the exact classical solution in presence of a
fermionic background and calculate the full superdeterminant contributing to
the one-loop partition function. We find that the one-loop partition function
is not modified with respect to the usual N=1 super Yang-Mills.Comment: 27 pages, harmvac, Redone the computation of topological charge, a
section has been rewritten and references adde
New extended superconformal sigma models and Quaternion Kahler manifolds
Quaternion Kahler manifolds are known to be the target spaces for matter
hypermultiplets coupled to N=2 supergravity. It is also known that there is a
one-to-one correspondence between 4n-dimensional quaternion Kahler manifolds
and those 4(n+1)-dimensional hyperkahler spaces which are the target spaces for
rigid superconformal hypermultiplets (such spaces are called hyperkahler
cones). In this paper we present a projective-superspace construction to
generate a hyperkahler cone M^{4(n+1)}_H of dimension 4(n+1) from a
2n-dimensional real analytic Kahler-Hodge manifold M^{2n}_K. The latter emerges
as a maximal Kahler submanifold of the 4n-dimensional quaternion Kahler space
M^{4n}_Q such that its Swann bundle coincides with M^{4(n+1)}_H. Our approach
should be useful for the explicit construction of new quaternion Kahler
metrics. The results obtained are also of interest, e.g., in the context of
supergravity reduction N=2 --> N=1, or alternatively from the point of view of
embedding N=1 matter-coupled supergravity into an N=2 theory.Comment: 30 page
3D Printing of a Multi-Layered Polypill Containing Six Drugs Using a Novel Stereolithographic Method
YesThree-dimensional printing (3DP) has demonstrated great potential for multi-material
fabrication because of its capability for printing bespoke and spatially separated material
conformations. Such a concept could revolutionise the pharmaceutical industry, enabling the
production of personalised, multi-layered drug products on demand. Here, we developed a novel
stereolithographic (SLA) 3D printing method that, for the first time, can be used to fabricate multi-layer
constructs (polypills) with variable drug content and/or shape. Using this technique, six drugs,
including paracetamol, cffeine, naproxen, chloramphenicol, prednisolone and aspirin, were printed
with dfferent geometries and material compositions. Drug distribution was visualised using Raman
microscopy, which showed that whilst separate layers were successfully printed, several of the drugs
diffused across the layers depending on their amorphous or crystalline phase. The printed constructs
demonstrated excellent physical properties and the different material inclusions enabled distinct drug
release profiles of the six actives within dissolution tests. For the first time, this paper demonstrates the
feasibility of SLA printing as an innovative platform for multi-drug therapy production, facilitating a
new era of personalised polypills
Digestibility and IgE-Binding of Glycosylated Codfish Parvalbumin
Food-processing conditions may alter the allergenicity of food proteins by different means. In this study, the effect of the glycosylation as a result of thermal treatment on the digestibility and IgE-binding of codfish parvalbumin is investigated. Native and glycosylated parvalbumins were digested with pepsin at various conditions relevant for the gastrointestinal tract. Intact proteins and peptides were analysed for apparent molecular weight and IgE-binding. Glycosylation did not substantially affect the digestion. Although the peptides resulting from digestion were relatively large (3 and 4 kDa), the IgE-binding was strongly diminished. However, the glycosylated parvalbumin had a strong propensity to form dimers and tetramers, and these multimers bound IgE intensely, suggesting stronger IgE-binding than monomeric parvalbumin. We conclude that glycosylation of codfish parvalbumin does not affect the digestibility of parvalbumin and that the peptides resulting from this digestion show low IgE-binding, regardless of glycosylation. Glycosylation of parvalbumin leads to the formation of higher order structures that are more potent IgE binders than native, monomeric parvalbumin. Therefore, food-processing conditions applied to fish allergen can potentially lead to increased allergenicity, even while the protein's digestibility is not affected by such processing
Characterization of the n-TOF EAR-2 neutron beam
The experimental area 2 (EAR-2) at CERNs neutron time-of-flight facility (n-TOF), which is operational since 2014, is designed and built as a short-distance complement to the experimental area 1 (EAR-1). The Parallel Plate Avalanche Counter (PPAC) monitor experiment was performed to characterize the beam prole and the shape of the neutron 'ux at EAR-2. The prompt γ-flash which is used for calibrating the time-of-flight at EAR-1 is not seen by PPAC at EAR-2, shedding light on the physical origin of this γ-flash
The measurement programme at the neutron time-of-flight facility n-TOF at CERN
Neutron-induced reaction cross sections are important for a wide variety of research fields ranging from the study of nuclear level densities, nucleosynthesis to applications of nuclear technology like design, and criticality and safety assessment of existing and future nuclear reactors, radiation dosimetry, medical applications, nuclear waste transmutation, accelerator-driven systems and fuel cycle investigations. Simulations and calculations of nuclear technology applications largely rely on evaluated nuclear data libraries. The evaluations in these libraries are based both on experimental data and theoretical models. CERN's neutron time-of-flight facility n-TOF has produced a considerable amount of experimental data since it has become fully operational with the start of its scientific measurement programme in 2001. While for a long period a single measurement station (EAR1) located at 185 m from the neutron production target was available, the construction of a second beam line at 20 m (EAR2) in 2014 has substantially increased the measurement capabilities of the facility. An outline of the experimental nuclear data activities at n-TOF will be presented
Search for a W' boson decaying to a bottom quark and a top quark in pp collisions at sqrt(s) = 7 TeV
Results are presented from a search for a W' boson using a dataset
corresponding to 5.0 inverse femtobarns of integrated luminosity collected
during 2011 by the CMS experiment at the LHC in pp collisions at sqrt(s)=7 TeV.
The W' boson is modeled as a heavy W boson, but different scenarios for the
couplings to fermions are considered, involving both left-handed and
right-handed chiral projections of the fermions, as well as an arbitrary
mixture of the two. The search is performed in the decay channel W' to t b,
leading to a final state signature with a single lepton (e, mu), missing
transverse energy, and jets, at least one of which is tagged as a b-jet. A W'
boson that couples to fermions with the same coupling constant as the W, but to
the right-handed rather than left-handed chiral projections, is excluded for
masses below 1.85 TeV at the 95% confidence level. For the first time using LHC
data, constraints on the W' gauge coupling for a set of left- and right-handed
coupling combinations have been placed. These results represent a significant
improvement over previously published limits.Comment: Submitted to Physics Letters B. Replaced with version publishe
Search for the standard model Higgs boson decaying into two photons in pp collisions at sqrt(s)=7 TeV
A search for a Higgs boson decaying into two photons is described. The
analysis is performed using a dataset recorded by the CMS experiment at the LHC
from pp collisions at a centre-of-mass energy of 7 TeV, which corresponds to an
integrated luminosity of 4.8 inverse femtobarns. Limits are set on the cross
section of the standard model Higgs boson decaying to two photons. The expected
exclusion limit at 95% confidence level is between 1.4 and 2.4 times the
standard model cross section in the mass range between 110 and 150 GeV. The
analysis of the data excludes, at 95% confidence level, the standard model
Higgs boson decaying into two photons in the mass range 128 to 132 GeV. The
largest excess of events above the expected standard model background is
observed for a Higgs boson mass hypothesis of 124 GeV with a local significance
of 3.1 sigma. The global significance of observing an excess with a local
significance greater than 3.1 sigma anywhere in the search range 110-150 GeV is
estimated to be 1.8 sigma. More data are required to ascertain the origin of
this excess.Comment: Submitted to Physics Letters
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