2,795 research outputs found
Sustainability of Semi‐Arid Extensive Livestock Systems in Senegal: Elements for Modelling Animal‐Plant Interactions
The hidden burden of adult allergic rhinitis : UK healthcare resource utilisation survey
Funding Funding for this survey was provided by Meda Pharma.Peer reviewedPublisher PD
A Case Study in Matching Test and Proof Coverage
AbstractThis paper studies the complementarity of test and deductive proof processes for Java programs specified in JML (Java Modeling Language). The proof of a program may be long and difficult, especially when automatic provers give up. When a theorem is not automatically proved, there are two possibilities: either the theorem is correct and there are not enough pieces of information to deal with the proof, or the theorem is incorrect. In order to discriminate between those two alternatives, testing techniques can be used. Here, we present experiments around the use of the JACK tool to prove Java programs annotated with JML assertions. When JACK fails to decide proof obligations, we use a combinatorial testing tool, TOBIAS, to produce large test suites that exercise the unproved program parts. The key issue is to establish the relevance of the test suite with respect to the unproved proof obligations. Therefore, we use code coverage techniques: our approach takes advantage of the statement orientation of the JACK tool to compare the statements involved in the unproved proof obligations and the statements covered by the test suite. Finally, we ensure our confidence within the test suites, by evaluating them on mutant program killing exercises. These techniques have been put into practice and are illustrated by a simple case study
Renewed methane increase for five years (2007–2011) observed by solar FTIR spectrometry
Trends of column-averaged methane for the time period (1996, Sep 2011) are derived from the mid-infrared (mid-IR) solar FTIR time series at the Zugspitze (47.42° N, 10.98° E, 2964 m a.s.l.) and Garmisch (47.48° N, 11.06° E, 743 m a.s.l.). Trend analysis comprises a fit to the de-seasonalized time series along with bootstrap resampling for quantifying trend uncertainties. We find a positive trend during [1996, 1998] of 9.0 [3.2, 14.7] ppb yr<sup>−1</sup> for Zugspitze (95% confidence interval), an insignificant growth during [1999, mid 2006] of 0.8 [−0.1, 1.7] ppb yr<sup>−1</sup> (Zugspitze), and a significant renewed increase during [mid 2006, Sep 2011] of 5.1 [4.2, 6.0] ppb yr<sup>−1</sup> for Garmisch, which is in agreement with 4.8 [3.8, 5.9] ppb yr<sup>−1</sup> for Zugspitze. <br></br> The agreement of methane trends at the two closely neighboring FTIR sites Zugspitze and Garmisch within the uncertainties indicates a good station-to-station consistency as a basis for future trend analyses by the ground-based mid-IR FTIR network on the global scale. Furthermore, the Zugspitze FTIR trend for the time interval [Jul 2006, Jun 2009] is found to agree with the trend derived from SCIAMACHY (WFM-DOAS v2.0.2) data within the 95% confidence intervals. In case a 1000-km pixel selection radius around the Zugspitze is used, the confidence interval is narrower for the FTIR trend (6.9 [4.2, 9.5] ppb yr<sup>−1</sup>) compared to SCIAMACHY (7.1 [5.1, 8.6] ppb yr<sup>−1</sup>). If, however, a loosened pixel selection is used (&approx;1000-km half-width latitudinal band), the SCIAMACHY trend significance interval is narrower (6.8 [5.1, 8.6] ppb yr<sup>−1</sup>) compared to Zugspitze FTIR (5.7 [3.0, 8.3] ppb yr<sup>−1</sup>). <br></br> While earlier studies using surface network data revealed changes of 8.0 ± 0.6 ppb in 2007, 6.4 ± 0.6 ppb in 2008, and 4.7 ± 0.6 ppb in 2009 (Dlugokencky et al., 2011), our updated result proves that the renewed methane increase meanwhile has been persisting for >5 years [mid 2006, Sep 2011]. This is either the longest and largest positive trend anomaly since the beginning of systematic observations more than 25 years ago or the onset of a new period of strongly increasing CH<sub>4</sub> levels in the atmosphere. Several scenarios have been developed to explain the persistent increase observed, mainly invoking an increase in emissions from natural wetlands, an increase in fossil fuel-related emissions or a decrease in OH concentrations. However, more work is needed to fully attribute this increase to a particular source or sink
Non collinear magnetism and single ion anisotropy in multiferroic perovskites
The link between the crystal distortions of the perovskite structure and the
magnetic exchange interaction, the single-ion anisotropy (SIA) and the
Dzyaloshinsky-Moriya (DM) interaction are investigated by means of
density-functional calculations. Using BiFeO and LaFeO as model
systems, we quantify the relationship between the oxygen octahedra rotations,
the ferroelectricity and the weak ferromagnetism (wFM). We recover the fact
that the wFM is due to the DM interaction induced by the oxygen octahedra
rotations. We find a simple relationship between the wFM, the oxygen rotation
amplitude and the ratio between the DM vector and the exchange parameter such
as the wFM increases with the oxygen octahedra rotation when the SIA does not
compete with the DM forces induced on the spins. Unexpectedly, we also find
that, in spite of the electronic configuration of Fe, the SIA is
very large in some structures and is surprisingly strongly sensitive to the
chemistry of the -site cation of the BO perovskite. In the ground
state phase we show that the SIA shape induced by the ferroelectricity
and the oxygen octahedra rotations are in competition such as it is possible to
tune the wFM "on" and "off" through the relative size of the two types of
distortion
PACHYCHOROID: an inherited condition?
PURPOSE: Thick choroid (pachychoroid) is associated with central serous chorioretinopathy (CSC), but whether pachychoroid is inherited is unknown.
METHODS: In a prospective observational study, first- or second-degree relatives (16 individuals) of 5 patients with CSC had refraction and visual acuity measurement, fundus examination, nonmydriatic photography, and autofluorescence photography. Eyes were graded using the following criteria: 0: normal fundus and autofluorescence photography, 1: focal retinal pigment epithelium hyperfluorescence and/or hypofluorescence and/or retinal pigment epithelial detachment, 2: CSC or diffuse retinal epitheliopathy. Choroid thickness was measured by enhanced depth imaging mode on optical coherence tomography.
RESULTS: Considering 395 μm as the threshold limit for normal subfoveal choroidal thickness, 50% of the eyes from relatives had a thick choroid. Nine eyes of Grade 0 (28%) with an isolated pachychoroid would thus have been considered normal, if choroidal thickness was not included as a screening sign predisposing for CSC.
CONCLUSION: Our observation suggests that pachychoroid could be an inherited condition with potentially a dominant transmission mode. Its inclusion in the phenotype of CSC for genetic studies should be considered
Dynamics of metal clusters in rare gas clusters
We investigate the dynamics of Na clusters embedded in Ar matrices. We use a
hierarchical approach, accounting microscopically for the cluster's degrees of
freedom and more coarsely for the matrix. The dynamical polarizability of the
Ar atoms and the strong Pauli-repulsion exerted by the Ar-electrons are taken
into account. We discuss the impact of the matrix on the cluster gross
properties and on its optical response. We then consider a realistic case of
irradiation by a moderately intense laser and discuss the impact of the matrix
on the hindrance of the explosion, as well as a possible pump probe scenario
for analyzing dynamical responses.Comment: Proceedings of the 30th International Workshop on Condensed Matter
Theories, Dresden, June 05 - 10, 2006, World Scientific. 3 figure
MicroRNAs: the primary cause or a determinant of progression in leukemia?
available in PMC 2011 October 10.Leukemia is a complex disease with many different types and subtypes caused by a huge
diversity of genetic and epigenetic aberrations. Until recently, alterations of protein-coding
genes were thought to be the sole cause of tumorigenesis. With the recent discovery of
multiple types of non-coding RNAs, it has become evident that mutations in these also
contribute to the development of cancer. Among the non-coding RNAs, microRNAs play a
crucial role in cancer owing to their involvement in fundamental processes such as
apoptosis, differentiation and proliferation.
MicroRNAs are small noncoding RNAs (approximately 19–25 nucleotides in length) that
bind to and downregulate multiple mRNA targets; in mammals, the production of over a
third of all proteins is regulated by microRNAs [3]. Several studies demonstrated that
microRNAs are involved in leukemia progression but their role as the primary cause or a
determinant of progression in leukemia has been unclear. Some have been identified as
oncogenes or tumor suppressor genes, which suggests that they are playing a central role in
tumorigenesis, while others appear to be associated with a specific stage in disease
progression. Deciphering the exact role of microRNAs in oncogenesis is important in order
to improve the diagnosis and treatment of leukemia patients.National Institutes of Health (U.S.) (NIH grant DK068348)National Institutes of Health (U.S.) (NIH Grant 5P01 HL066105)Leukemia & Lymphoma Society of America (Recherche sur le Cancer (ARC) fellowship
La modélisation d'accompagnement : une méthode de recherche participative et adaptative
Ce chapitre vise à présenter la diversité dans la mise en ½uvre d'un processus de modélisation d'accompagnement, mais aussi les points communs qui en émergent. L'objectif est de décrire pour mieux comprendre, sans intention normative. Nous nous appuyons sur l'analyse des cas d'études et des documents listés dans l'introduction. Notre analyse rassemble des cas concrets et des pratiques qui se réclament de la modélisation d'accompagnement et qui seront donc considérés comme tels dans notre analyse. La compatibilité de la diversité observée avec le cadre d'une adhésion aux principes initiaux de la charte sort du cadre de ce chapitre, elle est traitée dans la conclusion générale de l'ouvrage
Direct evidence for ferroelectric polar distortion in ultrathin lead titanate perovskite films
X-ray photoelectron diffraction is used to directly probe the intra-cell
polar atomic distortion and tetragonality associated with ferroelectricity in
ultrathin epitaxial PbTiO3 films. Our measurements, combined with ab-initio
calculations, unambiguously demonstrate non-centro-symmetry in films a few unit
cells thick, imply that films as thin as 3 unit cells still preserve a
ferroelectric polar distortion, and also show that there is no thick
paraelectric dead layer at the surface
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