785 research outputs found
Bilateral linear scleroderma "en coup de sabre" associated with facial atrophy and neurological complications
BACKGROUND: Linear scleroderma "en coup de sabre" (LSCS) usually affects one side of the face and head in the frontoparietal area with band-like indurated skin lesions. The disease may be associated with facial hemiatrophy. Various ophthalmological and neurological abnormalities have been observed in patients with LSCS. We describe an unusual case of LSC. CASE PRESENTATION: A 23 year old woman presented bilateral LSCS and facial atrophy. The patient had epileptic seizures as well as oculomotor and facial nerve palsy on the left side which also had pronounced skin involvement. Clinical features of different stages of the disease are presented. CONCLUSIONS: The findings of the presented patient with bilateral LSCS and facial atrophy provide further evidence for a neurological etiology of the disease and may also indicate that classic progressive facial hemiatrophy (Parry-Romberg syndrome) and LSCS actually represent different spectra of the same disease
Non-supersymmetric heterotic model building
We investigate orbifold and smooth Calabi-Yau compactifications of the
non-supersymmetric heterotic SO(16)xSO(16) string. We focus on such Calabi-Yau
backgrounds in order to recycle commonly employed techniques, like index
theorems and cohomology theory, to determine both the fermionic and bosonic 4D
spectra. We argue that the N=0 theory never leads to tachyons on smooth
Calabi-Yaus in the large volume approximation. As twisted tachyons may arise on
certain singular orbifolds, we conjecture that such tachyonic states are lifted
in the full blow-up. We perform model searches on selected orbifold geometries.
In particular, we construct an explicit example of a Standard Model-like theory
with three generations and a single Higgs field.Comment: 1+30 pages latex, 11 tables; v2: references and minor revisions
added, matches version published in JHE
Effects of serum proteins on corrosion behavior of ISO 5832–9 alloy modified by titania coatings
Stainless steel ISO 5832–9 type is often used to
perform implants which operate in protein-containing physiological
environments. The interaction between proteins and
surface of the implant may affect its corrosive properties. The
aim of this work was to study the effect of selected serum
proteins (albumin and γ-globulins) on the corrosion of ISO
5832–9 alloy (trade name M30NW) which surface was modified
by titania coatings. These coatings were obtained by sol–
gel method and heated at temperatures of 400 and 800 °C. To
evaluate the effect of the proteins, the corrosion tests were
performed with and without the addition of proteins with
concentration of 1 g L−1 to the physiological saline solution
(0.9 % NaCl, pH 7.4) at 37 °C. The tests were carried out
within 7 days. The following electrochemical methods were
used: open circuit potential, linear polarization resistance, and
electrochemical impedance spectroscopy. In addition, surface
analysis by optical microscopy and X-ray photoelectron spectroscopy
(XPS) method was done at the end of weekly corrosion
tests. The results of corrosion tests showed that M30NW
alloy both uncoated and modified with titania coatings exhibits
a very good corrosion resistance during weekly exposition
to corrosion medium. The best corrosion resistance in
0.9 % NaCl solution is shown by alloy samples modified by
titania coating annealed at 400 °C. The serumproteins have no
significant effect onto corrosion of investigated biomedical
steel. The XPS results confirmed the presence of proteins on
the alloy surface after 7 days of immersion in proteincontaining
solutions.The investigations were supported by the National Science Centre project No. N N507 501339. The authors gratefully acknowledge Dr. Janusz
Sobczak and Dr. hab. Wojciech Lisowski from Institute of Physical
Chemistry of PAS for XPS surface analyses
Lst4, the yeast Fnip1/2 orthologue, is a DENN-family protein.
The folliculin/Fnip complex has been demonstrated to play a crucial role in the mechanisms underlying Birt-Hogg-Dubé (BHD) syndrome, a rare inherited cancer syndrome. Lst4 has been previously proposed to be the Fnip1/2 orthologue in yeast and therefore a member of the DENN family. In order to confirm this, we solved the crystal structure of the N-terminal region of Lst4 from Kluyveromyces lactis and show it contains a longin domain, the first domain of the full DENN module. Furthermore, we demonstrate that Lst4 through its DENN domain interacts with Lst7, the yeast folliculin orthologue. Like its human counterpart, the Lst7/Lst4 complex relocates to the vacuolar membrane in response to nutrient starvation, most notably in carbon starvation. Finally, we express and purify the recombinant Lst7/Lst4 complex and show that it exists as a 1 : 1 heterodimer in solution. This work confirms the membership of Lst4 and the Fnip proteins in the DENN family, and provides a basis for using the Lst7/Lst4 complex to understand the molecular function of folliculin and its role in the pathogenesis of BHD syndrome.AP, BKB and RKN were supported by the Myrovlytis Trust. DBA was supported by a NHMRC CJ Martin Fellowship (APP1072476). LHW was supported by Medical Research Council (MRC) studentship, MR/J006580/1 and TPL by University College London. SD was supported by Fondation de France, La Ligue National contre le Cancer (Comité de Paris / Ile-de-France and Comité de l’Oise); TLB and NZ thank the University of Cambridge and The Wellcome Trust for facilities and support.This is the final version of the article. It was first available from Royal Society Publishing via http://dx.doi.org/10.1098/rsob.15017
6D Effective Action of Heterotic Compactification on K3 with nontrivial Gauge Bundles
We compute the six-dimensional effective action of the heterotic string
compactified on K3 for the standard embedding and for a class of backgrounds
with line bundles and appropriate Yang-Mills fluxes. We compute the couplings
of the charged scalars and the bundle moduli as functions of the geometrical K3
moduli from a Kaluza-Klein analysis. We derive the D-term potential and show
that in the flux backgrounds U(1) vector multiplets become massive by a
Stuckelberg mechanism.Comment: 41 pages, typos corrected, references adde
Transparent nanometric organic luminescent films as UV-active components in photonic structures
A new kind of visible-blind organic thin-film material, consisting of a polymeric matrix with a high concentration of embedded 3-hydroxyflavone (3HF) dye molecules, that absorbs UV light and emits green light is presented. The thin films can be grown on sensitive substrates, including flexible polymers and paper. Their suitability as photonic active components photonic devices is demonstrated. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
A Global SU(5) F-theory model with Wilson line breaking
We engineer compact SU(5) Grand Unified Theories in F-theory in which
GUT-breaking is achieved by a discrete Wilson line. Because the internal gauge
field is flat, these models avoid the high scale threshold corrections
associated with hypercharge flux. Along the way, we exemplify the
`local-to-global' approach in F-theory model building and demonstrate how the
Tate divisor formalism can be used to address several challenges of extending
local models to global ones. These include in particular the construction of
G-fluxes that extend non-inherited bundles and the engineering of U(1)
symmetries. We go beyond chirality computations and determine the precise
(charged) massless spectrum, finding exactly three families of quarks and
leptons but excessive doublet and/or triplet pairs in the Higgs sector
(depending on the example) and vector-like exotics descending from the adjoint
of SU(5)_{GUT}. Understanding why vector-like pairs persist in the Higgs sector
without an obvious symmetry to protect them may shed light on new solutions to
the mu problem in F-theory GUTs.Comment: 95 pages (71 pages + 1 Appendix); v2 references added, minor
correction
Heterotic Line Bundle Standard Models
In a previous publication, arXiv:1106.4804, we have found 200 models from
heterotic Calabi-Yau compactifications with line bundles, which lead to
standard models after taking appropriate quotients by a discrete symmetry and
introducing Wilson lines. In this paper, we construct the resulting standard
models explicitly, compute their spectrum including Higgs multiplets, and
analyze some of their basic properties. After removing redundancies we find
about 400 downstairs models, each with the precise matter spectrum of the
supersymmetric standard model, with one, two or three pairs of Higgs doublets
and no exotics of any kind. In addition to the standard model gauge group, up
to four Green-Schwarz anomalous U(1) symmetries are present in these models,
which constrain the allowed operators in the four-dimensional effective
supergravity. The vector bosons associated to these anomalous U(1) symmetries
are massive. We explicitly compute the spectrum of allowed operators for each
model and present the results, together with the defining data of the models,
in a database of standard models accessible at
http://www-thphys.physics.ox.ac.uk/projects/CalabiYau/linebundlemodels/index.html.
Based on these results we analyze elementary phenomenological properties. For
example, for about 200 models all dimension four and five proton decay
violating operators are forbidden by the additional U(1) symmetries.Comment: 55 pages, Latex, 3 pdf figure
Gauged Linear Sigma Models for toroidal orbifold resolutions
Toroidal orbifolds and their resolutions are described within the framework
of (2,2) Gauged Linear Sigma Models (GLSMs). Our procedure describes two-tori
as hypersurfaces in (weighted) projective spaces. The description is chosen
such that the orbifold singularities correspond to the zeros of their
homogeneous coordinates. The individual orbifold singularities are resolved
using a GLSM guise of non-compact toric resolutions, i.e. replacing discrete
orbifold actions by Abelian worldsheet gaugings. Given that we employ the same
global coordinates for both the toroidal orbifold and its resolutions, our GLSM
formalism confirms the gluing procedure on the level of divisors discussed by
Lust et al. Using our global GLSM description we can study the moduli space of
such toroidal orbifolds as a whole. In particular, changes in topology can be
described as phase transitions of the underlying GLSM. Finally, we argue that
certain partially resolvable GLSMs, in which a certain number of fixed points
can never be resolved, might be useful for the study of mini-landscape orbifold
MSSMs.Comment: 71 pages, 2 figure
Linear Sigma Models with Torsion
Gauged linear sigma models with (0,2) supersymmetry allow a larger choice of
couplings than models with (2,2) supersymmetry. We use this freedom to find a
fully linear construction of torsional heterotic compactifications, including
models with branes. As a non-compact example, we describe a family of metrics
which correspond to deformations of the heterotic conifold by turning on
H-flux. We then describe compact models which are gauge-invariant only at the
quantum level. Our construction gives a generalization of symplectic reduction.
The resulting spaces are non-Kahler analogues of familiar toric spaces like
complex projective space. Perturbatively conformal models can be constructed by
considering intersections.Comment: 40 pages, LaTeX, 1 figure; references added; a new section on
supersymmetry added; quantization condition revisite
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