127 research outputs found
A preliminary analysis of in-depth accident data for powered two-wheelers and bicycles in Europe
Despite progress from scientific and technological advancements, road safety remains a major issue worldwide. Road accident impacts such as fatalities, injuries and property damage consist considerable costs borne not only by involved people but society as well. This study aims to present preliminary findings of in-depth accident analysis for two-wheelers (bicycles and powered two wheelers â PTWs) across six countries in Europe. Data regarding the conditions underlying accident occurrence are presented, including time and date, weather, vehicle and road conditions and rider-related parameters such as age, intoxication and use of protective equipment. In addition, a Two Step Cluster Analysis is implemented in order to explore any possible classification of the analysed cases. It appears that two clusters are formed: the first includes more favourable conditions (âno wind, no drugs, good lightingâ) while the second consists of less favourable conditions for road safety (âwindy, lighting, unknown DUI conditionâ). This hints at a meaningful separation of the examination of two-wheeler accidents when the influence of outside factors is considerable. The inclusion of different but representative areas across Europe offers robustness and transferability to the data and respective results
An index for the Dirac operator on D3 branes with background fluxes
We study the problem of instanton generated superpotentials in Calabi-Yau
orientifold compactifications directly in type IIB string theory. To this end,
we derive the Dirac equation on a Euclidean D3 brane in the presence of
background fluxes. We propose an index which governs whether the generation of
a superpotential in the effective 4d theory by D3 brane instantons is possible.
Applying the formalism to various classes of examples, including the K3 x
T^2/Z_2 orientifold, in the absence and presence of fluxes, we show that our
results are consistent with conclusions attainable via duality from an M-theory
analysis.Comment: Fermion coupling to five-form restored, conclusions of the paper
unchange
Author Correction: Genome-Guided Phylo-Transcriptomic Methods and the Nuclear Phylogenetic Tree of the Paniceae Grasses
The original version of this Article contained an error in the title of the paper, where the word âPhylogeneticâ was incorrectly given as âPhylogenticâ. This has now been corrected in the PDF and HTML versions of the Article, and in the accompanying Supplementary Information file
D-instantons and twistors: some exact results
We present some results on instanton corrections to the hypermultiplet moduli
space in Calabi-Yau compactifications of Type II string theories. Previously,
using twistor methods, only a class of D-instantons (D2-instantons wrapping
A-cycles) was incorporated exactly and the rest was treated only linearly. We
go beyond the linear approximation and give a set of holomorphic functions
which, through a known procedure, capture the effect of D-instantons at all
orders. Moreover, we show that for a sector where all instanton charges have
vanishing symplectic invariant scalar product, the hypermultiplet metric can be
computed explicitly.Comment: 32 pages, 3 figures, uses JHEP3.cls; some changes in section 3.3.3;
corrected formula for the contact potentia
Membrane Instantons and de Sitter Vacua
We investigate membrane instanton effects in type IIA strings compactified on
rigid Calabi-Yau manifolds. These effects contribute to the low-energy
effective action of the universal hypermultiplet. In the absence of additional
fivebrane instantons, the quaternionic geometry of this hypermultiplet is
determined by solutions of the three-dimensional Toda equation. We construct
solutions describing membrane instantons, and find perfect agreement with the
string theory prediction. In the context of flux compactifications we discuss
how membrane instantons contribute to the scalar potential and the
stabilization of moduli. Finally, we demonstrate the existence of meta-stable
de Sitter vacua.Comment: v3: minor clarifications, JHEP version, 38 page
Metastable de Sitter vacua in N=2 to N=1 truncated supergravity
We study the possibility of achieving metastable de Sitter vacua in general
N=2 to N=1 truncated supergravities without vector multiplets, and compare with
the situations arising in N=2 theories with only hypermultiplets and N=1
theories with only chiral multiplets. In N=2 theories based on a quaternionic
manifold and a graviphoton gauging, de Sitter vacua are necessarily unstable,
as a result of the peculiar properties of the geometry. In N=1 theories based
on a Kahler manifold and a superpotential, de Sitter vacua can instead be
metastable provided the geometry satisfies some constraint and the
superpotential can be freely adjusted. In N=2 to N=1 truncations, the crucial
requirement is then that the tachyon of the mother theory be projected out from
the daughter theory, so that the original unstable vacuum is projected to a
metastable vacuum. We study the circumstances under which this may happen and
derive general constraints for metastability on the geometry and the gauging.
We then study in full detail the simplest case of quaternionic manifolds of
dimension four with at least one isometry, for which there exists a general
parametrization, and study two types of truncations defining Kahler
submanifolds of dimension two. As an application, we finally discuss the case
of the universal hypermultiplet of N=2 superstrings and its truncations to the
dilaton chiral multiplet of N=1 superstrings. We argue that de Sitter vacua in
such theories are necessarily unstable in weakly coupled situations, while they
can in principle be metastable in strongly coupled regimes.Comment: 40 pages, no figure
Low Energy Supersymmetry from Non-Geometry
We study a class of flux compactifications that have all the moduli
stabilised, a high (GUT) string scale and a low (TeV) gravitino mass that is
generated dynamically. These non-geometric compactifications correspond to type
II string theories on SU(3)xSU(3) structure orientifolds. The resulting
superpotentials admit, excluding non-perturbative effects, supersymmetric
Minkowski vacua with any number of moduli stabilised. We argue that
non-perturbative effects are present and introduce terms in the superpotential
that are exponentially suppressed by the same moduli that appear
perturbatively. These deform the supersymmetric Minkowski vacua to
supersymmetric AdS vacua with an exponentially small gravitino mass. The
resulting vacua allow for low scale supersymmetry breaking which can be
realised by a number of mechanisms.Comment: 36pp; v2 references added, minor clarifications, JHEP versio
The MMSE should not be the sole indicator of fitness to drive in mild Alzheimer's dementia
Since Alzheimerâs disease may affect driving performance, patients with Alzheimerâs disease are assessed on fitness to drive. On-road driving assessments are widely used, and attempts have also been made to develop strategies to assess fitness to drive in a clinical setting. Preferably, a first indication of fitness to drive is obtained quickly after diagnosis using a single test such as the Mini-Mental State Examination (MMSE). The aim of this study is to investigate whether the MMSE can be used to predict whether patients with Alzheimerâs disease will pass or fail an on-road driving assessment. Patients with Alzheimerâs disease (n = 81) participated in a comprehensive fitness-to-drive assessment which included the MMSE as well as an on-road driving assessment [PLoS One 11(2):e0149566, 2016]. MMSE cutoffs were applied as suggested by Versijpt and colleagues [Acta Neurol Belg 117(4):811â819, 2017]. All patients with Alzheimerâs disease who scored below the lower cutoff (MMSE †19) failed the on-road driving assessment. However, a third of the patients with Alzheimerâs disease who scored above the upper cutoff (MMSE â„ 25) failed the on-road driving assessment as well. We conclude that the MMSE alone has insufficient predictive value to correctly identify fitness to drive in patients with very mild-to-mild Alzheimerâs disease implicating the need for comprehensive assessments to determine fitness to drive in a clinical setting
Molecular characterization of beta-tubulin from Phakopsora pachyrhizi, the causal agent of Asian soybean rust
ÎČ-tubulins are structural components of microtubules and the targets of benzimidazole fungicides used to control many diseases of agricultural importance. Intron polymorphisms in the intron-rich genes of these proteins have been used in phylogeographic investigations of phytopathogenic fungi. In this work, we sequenced 2764 nucleotides of the ÎČ-tubulin gene (Pp tubB) in samples of Phakopsora pachyrhizi collected from seven soybean fields in Brazil. Pp tubB contained an open reading frame of 1341 nucleotides, including nine exons and eight introns. Exon length varied from 14 to 880 nucleotides, whereas intron length varied from 76 to 102 nucleotides. The presence of only four polymorphic sites limited the usefulness of Pp tubB for phylogeographic studies in P. pachyrhizi. The gene structures of Pp tubB and orthologous ÎČ-tubulin genes of Melampsora lini and Uromyces viciae-fabae were highly conserved. The amino acid substitutions in ÎČ-tubulin proteins associated with the onset of benzimidazole resistance in model organisms, especially at His 6 , Glu 198 and Phe 200 , were absent from the predicted sequence of the P. pachyrhizi ÎČ-tubulin protein
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