462 research outputs found
Estimating the large-scale angular power spectrum in the presence of systematics: a case study of Sloan Digital Sky Survey quasars
The angular power spectrum is a powerful statistic for analysing cosmological
signals imprinted in the clustering of matter. However, current galaxy and
quasar surveys cover limited portions of the sky, and are contaminated by
systematics that can mimic cosmological signatures and jeopardise the
interpretation of the measured power spectra. We provide a framework for
obtaining unbiased estimates of the angular power spectra of large-scale
structure surveys at the largest scales using quadratic estimators. The method
is tested by analysing the 600 CMASS mock catalogues constructed by Manera et
al. (2013) for the Baryon Oscillation Spectroscopic Survey (BOSS). We then
consider the Richards et al. (2009) catalogue of photometric quasars from the
Sixth Data Release (DR6) of the Sloan Digital Sky Survey (SDSS), which is known
to include significant stellar contamination and systematic uncertainties.
Focusing on the sample of ultraviolet-excess (UVX) sources, we show that the
excess clustering power present on the largest-scales can be largely mitigated
by making use of improved sky masks and projecting out the modes corresponding
to the principal systematics. In particular, we find that the sample of objects
with photometric redshift exhibits no evidence of
contamination when using our most conservative mask and mode projection. This
indicates that any residual systematics are well within the statistical
uncertainties. We conclude that, using our approach, this sample can be used
for cosmological studies.Comment: 18 pages, 18 figures. Version accepted by MNRA
The role of time in considering collections
The paper concerns the understanding of plurals in the framework of Artificial Intelligence and emphasizes the role of time. The construction of collection(s) and their evolution across time is often crucial and has to be accounted for. The paper contrasts a "de dicto" collection where the collection can be considered as persisting over these situations even if its members change with a "de re" collection whose composition does not vary through time. It expresses different criteria of choice between the two interpretations (de re and de dicto) depending on the context of enunciation
Fonctions de la pseudo-traduction Ă l'aube des guerres civiles anglaises (1641-1642)
Longtemps considĂ©rĂ©e marginale dans lâĂ©tude de la traduction, la pseudo-traduction est devenue depuis quelques annĂ©es un sujet de plus en plus Ă©tudiĂ© en traductologie. Cependant, quâen est-il des fonctions que celle-ci occupe dans le systĂšme littĂ©raire dans lequel elle a Ă©tĂ© crĂ©Ă©e ? Lorsque Gideon Toury applique la thĂ©orie des polysystĂšmes au domaine de la traduction, il semble conclure quâune des fonctions majeures de la pseudo-traduction est dâintroduire un nouveau genre littĂ©raire dans une culture donnĂ©e. Mais cette hypothĂšse, si elle peut ĂȘtre appliquĂ©e aux pseudo-traductions littĂ©raires, semble un peu moins convenir Ă une certaine littĂ©rature populaire, que lâon retrouve sous forme de tracts. Le prĂ©sent mĂ©moire visera, Ă partir dâune analyse minutieuse de quatre cas dâĂ©tude, de leurs agents et de leurs paratextes, Ă dĂ©couvrir les fonctions de la pseudo-traduction de pamphlets imprimĂ©s Ă lâaube des guerres civiles anglaises (1641-1642).Once considered marginal in translation studies, pseudotranslations have become in recent years a subject much more carefully studied. It seems however that not angles have been covered, namely the functions that fictitious translations occupy in a given literary system. When Toury introduced the polysystemic theory in translation studies, he concluded that one of the major functions pseudotranslations serve is to introduce a new genre into a specific literary system. This hypothesis, while convenient for many literary pseudotranslations, seems a little less suitable for a certain type of popular literature, namely one found in the form of pamphlets. The present paper, based on a careful analysis of four case studies emphasizing the paratextual and agency aspects, will aim to discover the functions of pseudotranslations printed at the dawn of the English civil wars (1641- 1642)
Challenging the principle of compositionality in interpreting natural language texts
The paper aims at emphasizing that, even relaxed, the hypothesis of
compositionality has to face many problems when used for interpreting natural
language texts. Rather than fixing these problems within the compositional
framework, we believe that a more radical change is necessary, and propose
another approach
Structural role of PufX in the dimerization of the photosynthetic core complex of Rhodobacter sphaeroides.
Monomeric and dimeric PufX-containing core complexes have been purified from membranes of wild-type Rhodobacter sphaeroides. Reconstitution of both samples by detergent removal in the presence of lipids leads to the formation of two-dimensional crystals constituted of dimeric core complexes. Two-dimensional crystals were further analyzed by cryoelectron microscopy and atomic force microscopy. A projection map at 26-A resolution reveals that core complexes assemble in an "S"-shaped dimeric complex. Each core complex is composed of one reaction center, 12 light-harvesting 1 alpha/beta-heterodimers, and one PufX protein. The light-harvesting 1 assemblies are open with a gap of density of approximately 30-A width and surround oriented reaction centers. A maximum density is found at the dimer junction. Based on the projection map, a model is proposed, in which the two PufX proteins are located at the dimer junction, consistent with the finding of dimerization of monomeric core complexes upon reconstitution. This localization of PufX in the core complex implies that PufX is the structural key for the dimer complex formation rather than a channel-forming protein for the exchange of ubiquinone/ubiquinol between the reaction center and the cytochrome bc1 complex
Molecular and immunological evaluation of the expression of cancer/testis gene products in human colorectal cancer
Tumor-specific gene products, such as cancer/testis (CT) antigens, constitute promising targets for the development of T cell vaccines. Whereas CT antigens are frequently expressed in melanoma, their expression in colorectal cancers (CRC) remains poorly characterized. Here, we have studied the expression of the CT antigens MAGE-A3, MAGE-A4, MAGE-A10, NY-ESO-1 and SSX2 in CRC because of the presence of well-described HLA-A2-restricted epitopes in their sequences. Our analyses of 41 primary CRC and 14 metastatic liver lesions confirmed the low frequency of expression of these CT antigens. No increased expression frequencies were observed in metastatic tumors compared to primary tumors. Histological analyses of CRC samples revealed heterogeneous expression of individual CT antigens. Finally, evidence of a naturally acquired CT antigen-specific CD8+ T cell response could be demonstrated. These results show that the expression of CT antigens in a subset of CRC patients induces readily detectable T cell response
Septinâbased readout of PI(4,5)P2 incorporation into membranes of giant unilamellar vesicles
International audienceSeptins constitute a novel class of cytoskeletal proteins. Budding yeast septins self-assemble into non-polar filaments bound to the inner plasma membrane through specific interactions with L-α-phosphatidylinositol-4,5-bisphosphate (PI(4,5)P2). Biomimetic in vitro assays using Giant Unilamellar Vesicles (GUVs) are relevant tools to dissect and reveal insights in proteins-lipids interactions, membrane mechanics and curvature sensitivity. GUVs doped with PI(4,5)P2 are challenging to prepare. This report is dedicated to optimize the incorporation of PI(4,5)P2 lipids into GUVs by probing the proteins-PI(4,5)P2 GUVs interactions. We show that the interaction between budding yeast septins and PI(4,5)P2 is more specific than using usual reporters (phospholipase Cï€1). Septins have thus been chosen as reporters to probe the proper incorporation of PI(4,5)P2 into giant vesicles. We have shown that electro-formation on platinum wires is the most appropriate method to achieve an optimal septin-lipid interaction resulting from an optimal PI(4,5)P2 incorporation for which, we have optimized the growth conditions. Finally, we have shown that PI(4,5)P2 GUVs have to be used within a few hours after their preparation. Indeed, over time, PI(4,5)P2 is expelled from the GUV membrane and the PI(4,5)P2 concentration in the bilayer decreases
Tailoring the surface charge of dextran-based polymer coated SPIONs for modulated stem cell uptake and MRI contrast
Tracking stem cells in vivo using non-invasive techniques is critical to evaluate the efficacy and safety of stem cell therapies. Superparamagnetic iron oxide nanoparticles (SPIONs) enable cells to be tracked using magnetic resonance imaging (MRI), but to obtain detectable signal cells need to be labelled with a sufficient amount of iron oxide. For the majority of SPIONs, this can only be obtained with the use of transfection agents, which can adversely affect cell health. Here, we have synthesised a library of dextran-based polymer coated SPIONs with varying surface charge from â1.5 mV to +18.2 mV via a co-precipitation approach and investigated their ability to be directly internalised by stem cells without the need for transfection agents. The SPIONs were colloidally stable in physiological solutions. The crystalline phase of the particles was confirmed with powder X-ray diffraction and their magnetic properties were characterised using SQUID magnetometry and magnetic resonance. Increased surface charge led to six-fold increase in uptake of particles into stem cells and higher MRI contrast, with negligible change in cell viability. Cell tracking velocimetry was shown to be a more accurate method for predicting MRI contrast of stem cells compared to measuring iron oxide uptake through conventional bulk iron quantification
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