All-Optical Manipulation of Electron Spins in Carbon-Nanotube Quantum Dots

We demonstrate theoretically that it is possible to manipulate electron or hole spins all optically in semiconducting carbon nanotubes. The scheme that we propose is based on the spin-orbit interaction that was recently measured experimentally; we show that this interaction, together with an external magnetic field, can be used to achieve optical electron-spin state preparation with a fidelity exceeding 99%. Our results also imply that it is possible to implement coherent spin rotation and measurement using laser fields linearly polarized along the nanotube axis, as well as to convert spin qubits into time-bin photonic qubits. We expect that our findings will open up new avenues for exploring spin physics in one-dimensional systems

A purely geometric distance to the binary star Atlas, a member of the Pleiades

We present radial velocity and new interferometric measurements of the double star Atlas, which permit, with the addition of published interferometric data, to precisely derive the orbital parameters of the binary system and the masses of the components. The derived semi-major axis, compared with its measured angular size, allows to determine a distance to Atlas of 132+-4 pc in a purely geometrical way. Under the assumption that the location of Atlas is representative of the average distance of the cluster, we confirm the distance value generally obtained through main sequence fitting, in contradiction with the early Hipparcos result (118.3+-3.5 pc).Comment: 5 pages, 3 figures, accepted for publication in A&A Letter

Tumor-Derived Mesenchymal Stem Cells Use Distinct Mechanisms to Block the Activity of Natural Killer Cell Subsets.

Mesenchymal stem cells (MSCs) display pleiotropic functions, which include secretion of soluble factors with immunosuppressive activity implicated in cancer progression. We compared the immunomodulatory effects on natural killer (NK) cells of paired intratumor (T)- and adjacent non-tumor tissue (N)-derived MSCs from patients with squamous cell lung carcinoma (SCC). We observed that T-MSCs were more strongly immunosuppressive than N-MSCs and affected both NK function and phenotype, as defined by CD56 expression. T-MSCs shifted NK cells toward the CD56 <sup>dim</sup> phenotype and differentially modulated CD56 <sup>bright/dim</sup> subset functions. Whereas MSCs affected both degranulation and activating receptor expression in the CD56 <sup>dim</sup> subset, they primarily inhibited interferon-γ production in the CD56 <sup>bright</sup> subset. Pharmacological inhibition of prostaglandin E2 (PGE2) synthesis and, in some MSCs, interleukin-6 (IL-6) activity restored NK function, whereas NK cell stimulation by PGE2 alone mimicked T-MSC-mediated immunosuppression. Our observations provide insight into how stromal responses to cancer dampen NK cell activity in human lung SCC

Extrasolar planets and brown dwarfs around A--F type stars. VIII. A giant planet orbiting the young star HD113337

In the frame of the search for extrasolar planets and brown dwarfs around early-type main-sequence stars, we present the detection of a giant planet around the young F-type star HD113337. We estimated the age of the system to be 150 +100/-50 Myr. Interestingly, an IR excess attributed to a cold debris disk was previously detected on this star. The SOPHIE spectrograph on the 1.93m telescope at Observatoire de Haute-Provence was used to obtain ~300 spectra over 6 years. We used our SAFIR tool, dedicated to the spectra analysis of A and F stars, to derive the radial velocity variations. The data reveal a 324.0 +1.7/-3.3 days period that we attribute to a giant planet with a minimum mass of 2.83 +- 0.24 Mjup in an eccentric orbit with e=0.46 +- 0.04. A long-term quadratic drift, that we assign to be probably of stellar origin, is superimposed to the Keplerian solution.Comment: 7 pages, 4 figure

A new post-metallocene-ti catalyst with maltolate bidentade ligand: an investigation in heterogeneous polymerization reactions in different mesoporous supports

A new titanium catalyst easily synthesized from ethylmaltol bidentate chelator ligand was studied in homogeneous and heterogeneous ethylene polymerization. The dichlorobis(3-hydroxy-2-ethyl-4-pyrone)titanium(IV) complex was characterized by 1H and 13C NMR (nuclear magnetic resonance), UV-Vis and elemental analysis. Theoretical study by density functional theory (DFT) showed that the complex chlorines exhibit cis configuration, which is important for the activity in olefin polymerization. The complex was supported by two methods, direct impregnation or methylaluminoxane (MAO) pre-treatment, in five mesoporous supports: MCM-41 (micro and nano), SBA-15 and also the corresponding modified Al species. All the catalytic systems were active in ethylene polymerization and the catalytic activity was strongly influenced by the method of immobilization of the catalyst and the type of support.info:eu-repo/semantics/publishedVersio

Polyploidy in the Olive Complex (Olea europaea): Evidence from Flow Cytometry and Nuclear Microsatellite Analyses

Background Phylogenetic and phylogeographic investigations have been previously performed to study the evolution of the olive tree complex (Olea europaea). A particularly high genomic diversity has been found in north-west Africa. However, to date no exhaustive study has been addressed to infer putative polyploidization events and their evolutionary significance in the diversification of the olive tree and its relatives. Methods Representatives of the six olive subspecies were investigated using (a) flow cytometry to estimate genome content, and (b) six highly variable nuclear microsatellites to assess the presence of multiple alleles at co-dominant loci. In addition, nine individuals from a controlled cross between two individuals of O. europaea subsp. maroccana were characterized with microsatellites to check for chromosome inheritance. Key Results Based on flow cytometry and genetic analyses, strong evidence for polyploidy was obtained in subspp. cerasiformis (tetraploid) and maroccana (hexaploid), whereas the other subspecies appeared to be diploids. Agreement between flow cytometry and genetic analyses gives an alternative approach to chromosome counting to determine ploidy level of trees. Lastly, abnormalities in chromosomes inheritance leading to aneuploid formation were revealed using microsatellite analyses in the offspring from the controlled cross in subsp. maroccana. Conclusions This study constitutes the first report for multiple polyploidy in olive tree relatives. Formation of tetraploids and hexaploids may have played a major role in the diversification of the olive complex in north-west Africa. The fact that polyploidy is found in narrow endemic subspecies from Madeira (subsp. cerasiformis) and the Agadir Mountains (subsp. maroccana) suggests that polyploidization has been favoured to overcome inbreeding depression. Lastly, based on previous phylogenetic analyses, we hypothesize that subsp. cerasiformis resulted from hybridization between ancestors of subspp. guanchica and europae

Radial Velocities with CRIRES: Pushing precision down to 5-10 m/s

With the advent of high-resolution infrared spectrographs, Radial Velocity (RV) searches enter into a new domain. As of today, the most important technical question to address is which wavelength reference is the most suitable for high-precision RV measurements. In this work we explore the usage of atmospheric absorption features. We make use of CRIRES data on two programs and three different targets. We re-analyze the data of the TW Hya campaign, reaching a dispersion of about 6 m/s on the RV standard in a time scale of roughly 1 week. We confirm the presence of a low-amplitude RV signal on TW Hya itself, roughly 3 times smaller than the one reported at visible wavelengths. We present RV measurements of Gl 86 as well, showing that our approach is capable of detecting the signal induced by a planet and correctly quantifying it. Our data show that CRIRES is capable of reaching a RV precision of less than 10 m/s in a time-scale of one week. The limitations of this particular approach are discussed, and the limiting factors on RV precision in the IR in a general way. The implications of this work on the design of future dedicated IR spectrographs are addressed as well.Comment: 9 pages, accepted for publication in A&

Survival of icy grains in debris discs. The role of photosputtering

We put theoretical constraints on the presence and survival of icy grains in debris discs. Particular attention is paid to UV sputtering of water ice, which has so far not been studied in detail in this context. We present a photosputtering model based on available experimental and theoretical studies. We quantitatively estimate the erosion rate of icy and ice-silicate grains, under the influence of both sublimation and photosputtering, as a function of grain size, composition and distance from the star. The effect of erosion on the grain's location is investigated through numerical simulations coupling the grain size to its dynamical evolution. Our model predicts that photodesorption efficiently destroy ice in optically thin discs, even far beyond the sublimation snow line. For the reference case of beta Pictoris, we find that only > 5mm grains can keep their icy component for the age of the system in the 50-150AU region. When taking into account the collisional reprocessing of grains, we show that the water ice survival on grains improves (grains down to ~ 20 um might be partially icy). However, estimates of the amount of gas photosputtering would produce on such a hypothetical population of big icy grains lead to values for the OI column density that strongly exceed observational constraints for beta Pic, thus ruling out the presence of a significant amount of icy grains in this system. Erosion rates and icy grains survival timescales are also given for a set of 11 other debris disc systems. We show that, with the possible exception of M stars, photosputtering cannot be neglected in calculations of icy grain lifetimes.Comment: 12 pages, 9 figures. accepted by A&

A partitioned model order reduction approach to rationalise computational expenses in multiscale fracture mechanics

We propose in this paper an adaptive reduced order modelling technique based on domain partitioning for parametric problems of fracture. We show that coupling domain decomposition and projection-based model order reduction permits to focus the numerical effort where it is most needed: around the zones where damage propagates. No \textit{a priori} knowledge of the damage pattern is required, the extraction of the corresponding spatial regions being based solely on algebra. The efficiency of the proposed approach is demonstrated numerically with an example relevant to engineering fracture.Comment: Submitted for publication in CMAM