1,616 research outputs found

    Anomalous double peak structure in Nb/Ni superconductor/ferromagnet tunneling DOS

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    We have experimentally investigated the density of states (DOS) in Nb/Ni (S/F) bilayers as a function of Ni thickness, dFd_F. Our thinnest samples show the usual DOS peak at ±Δ0\pm\Delta_0, whereas intermediate-thickness samples have an anomalous ``double-peak'' structure. For thicker samples (dF3.5d_F \geq 3.5 nm), we see an ``inverted'' DOS which has previously only been reported in superconductor/weak-ferromagnet structures. We analyze the data using the self-consistent non-linear Usadel equation and find that we are able to quantitatively fit the features at ±Δ0\pm\Delta_0 if we include a large amount of spin-orbit scattering in the model. Interestingly, we are unable to reproduce the sub-gap structure through the addition of any parameter(s). Therefore, the observed anomalous sub-gap structure represents new physics beyond that contained in the present Usadel theory.Comment: 4 pages, 3 figure

    Arabidopsis glucosinolates trigger a contrasting transcriptomic response in a generalist and a specialist herbivore.

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    Phytophagous insects have to deal with toxic defense compounds from their host plants. Although it is known that insects have evolved genes and mechanisms to detoxify plant allochemicals, how specialist and generalist precisely respond to specific secondary metabolites at the molecular level is less understood. Here we studied the larval performance and transcriptome of the generalist moth Heliothis virescens and the specialist butterfly Pieris brassicae feeding on Arabidopsis thaliana genotypes with different glucosinolate (GS) levels. H. virescens larvae gained significantly more weight on the GS-deficient mutant quadGS compared to wild-type (Col-0) plants. On the contrary, P. brassicae was unaffected by the presence of GS and performed equally well on both genotypes. Strikingly, there was a considerable differential gene expression in H. virescens larvae feeding on Col-0 compared to quadGS. In contrast, compared to H. virescens, P. brassicae displayed a much-reduced transcriptional activation when fed on both plant genotypes. Transcripts coding for putative detoxification enzymes were significantly upregulated in H. virescens, along with digestive enzymes and transposable elements. These data provide an unprecedented view on transcriptional changes that are specifically activated by GS and illustrate differential molecular responses that are linked to adaptation to diet in lepidopteran herbivores

    Evaluation of far-field tsunami hazard in French Polynesia based on historical data and numerical simulations

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    International audienceThe first tsunami hazard map of French Polynesia is presented here on the basis of historical data, and numerical simulations. French Polynesia, because of its central position in the most tsunami prone ocean, the Pacific, is strongly exposed to far-field tsunamis. As no previous study on the area had been conducted, we compiled catalogues of all the historical observations (14 events), and tide gauges records (69 marigrams). The catalogues emphasise the higher hazard associated to the Marquesas archipelago, but also the deficiency of robust data in most other parts of French Polynesia. The recourse to numerical simulations allowed us to complement the existing records, and to test tsunami scenarii over different bathymetry and topography configurations, representative of the diversity of islands in French Polynesia. The tsunami hazard map assigns a high exposure level to the Marquesas and the island of Rurutu. Other islands of the Austral, and the Gambier archipelago have a elevated level of exposure, as well as three islands of Society: Tahiti, Moorea, and Huahine. All other islands of French Polynesia are considered as moderately exposed

    The size of selected human skull foramina in relation to skull capacity

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    An anatomical study was undertaken in order to investigate whether the sizes of selected human skull foramina with significant venous compartments correlated significantly with skull capacity. A total of 100 macerated human skulls were examined to determine the diameter of the foramina and the skull capacity. Measurements of the surface area of the foramina were made using a computerised digital analysis system. Only the size of the hypoglossal canal and jugular foramen were found to correlate significantly with the capacity of the skull. This correlation, together with the considerable size of the hypoglossal canal, indicated its important role in the venous drainage of the brain. There was considerable centralisation of venous outflow from the brain, with 60% of the area of all venous foramina of the skull occupied by jugular foramina. Asymmetry between the right and left jugular foramina was identified, with an average ratio of 1.6 (ranging between 1 and 3.47). In the case of right-sided domination the correlation between the skull capacity and the size of both jugular foramina was negative (the larger the skull cavity, the less the asymmetry), while in the case of left-sided domination the correlation was positive. Perhaps the left-sided domination is less advantageous for the haemodynamics of blood outflow, as the left brachiocephalic vein is longer and is often compressed by the sternum and aortic arch

    Experiments towards quantum information with trapped Calcium ions

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    Ground state cooling and coherent manipulation of ions in an rf-(Paul) trap is the prerequisite for quantum information experiments with trapped ions. With resolved sideband cooling on the optical S1/2 - D5/2 quadrupole transition we have cooled one and two 40Ca+ ions to the ground state of vibration with up to 99.9% probability. With a novel cooling scheme utilizing electromagnetically induced transparency on the S1/2 - P1/2 manifold we have achieved simultaneous ground state cooling of two motional sidebands 1.7 MHz apart. Starting from the motional ground state we have demonstrated coherent quantum state manipulation on the S1/2 - D5/2 quadrupole transition at 729 nm. Up to 30 Rabi oscillations within 1.4 ms have been observed in the motional ground state and in the n=1 Fock state. In the linear quadrupole rf-trap with 700 kHz trap frequency along the symmetry axis (2 MHz in radial direction) the minimum ion spacing is more than 5 micron for up to 4 ions. We are able to cool two ions to the ground state in the trap and individually address the ions with laser pulses through a special optical addressing channel.Comment: Proceedings of the ICAP 2000, Firenz

    The effect of homozygous deletion of the BBOX1 and Fibin genes on carnitine level and acyl carnitine profile.

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    BACKGROUND: Carnitine is a key molecule in energy metabolism that helps transport activated fatty acids into the mitochondria. Its homeostasis is achieved through oral intake, renal reabsorption and de novo biosynthesis. Unlike dietary intake and renal reabsorption, the importance of de novo biosynthesis pathway in carnitine homeostasis remains unclear, due to lack of animal models and description of a single patient defective in this pathway. CASE PRESENTATION: We identified by array comparative genomic hybridization a 42 months-old girl homozygote for a 221 Kb interstitial deletions at 11p14.2, that overlaps the genes encoding Fibin and butyrobetaine-gamma 2-oxoglutarate dioxygenase 1 (BBOX1), an enzyme essential for the biosynthesis of carnitine de novo. She presented microcephaly, speech delay, growth retardation and minor facial anomalies. The levels of almost all evaluated metabolites were normal. Her serum level of free carnitine was at the lower limit of the reference range, while her acylcarnitine to free carnitine ratio was normal. CONCLUSIONS: We present an individual with a completely defective carnitine de novo biosynthesis. This condition results in mildly decreased free carnitine level, but not in clinical manifestations characteristic of carnitine deficiency disorders, suggesting that dietary carnitine intake and renal reabsorption are sufficient to carnitine homeostasis. Our results also demonstrate that haploinsufficiency of BBOX1 and/or Fibin is not associated with Primrose syndrome as previously suggested

    Orchestrating the measurements on twelve magnet test benches

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    The final LHC dipole series test set-up will consist of 12 benches, organised in 6 clusters of two benches sharing the largest and most expensive devices. This sharing is made possible by a deliberate de-phasing of the tests among magnets, ensuring an optimum use of resources, such as cryogenics and power equipment, without limiting the total throughput. To orchestrate the measurements a Test Master is needed to organise the tests per cluster and a Resource Manager to centralise the booking of the resources

    Ground state cooling, quantum state engineering and study of decoherence of ions in Paul traps

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    We investigate single ions of 40Ca+^{40}Ca^+ in Paul traps for quantum information processing. Superpositions of the S1/2_{1/2} electronic ground state and the metastable D5/2_{5/2} state are used to implement a qubit. Laser light on the S1/2_{1/2} \leftrightarrow D5/2_{5/2} transition is used for the manipulation of the ion's quantum state. We apply sideband cooling to the ion and reach the ground state of vibration with up to 99.9% probability. Starting from this Fock state n=0>|n=0>, we demonstrate coherent quantum state manipulation. A large number of Rabi oscillations and a ms-coherence time is observed. Motional heating is measured to be as low as one vibrational quantum in 190 ms. We also report on ground state cooling of two ions.Comment: 12 pages, 6 figures. submitted to Journal of Modern Optics, Special Issue on Quantum Optics: Kuehtai 200

    Short, synthetic and selectively 13C-labeled RNA sequences for the NMR structure determination of protein-RNA complexes

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    We report an optimized synthesis of all canonical 2′-O-TOM protected ribonucleoside phosphoramidites and solid supports containing [13C5]-labeled ribose moieties, their sequence-specific introduction into very short RNA sequences and their use for the structure determination of two protein-RNA complexes. These specifically labeled sequences facilitate RNA resonance assignments and are essential to assign a high number of sugar-sugar and intermolecular NOEs, which ultimately improve the precision and accuracy of the resulting structures. This labeling strategy is particularly useful for the study of protein-RNA complexes with single-stranded RNA in solution, which is rapidly an increasingly relevant research area in biolog

    On the vertical extent of the large low shear velocity province beneath the South Pacific Superswell

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    International audienceThe three-dimensional S-wave velocity structure beneath the South Pacific Superswell is obtained from joint broadband seismic experiments on the ocean floor and islands. We collected only approximately 800 relative times of long-period teleseismic SH-waves by using a waveform cross-correlation from 76 events occurring from January 2003 to May 2005. We conducted relative time tomography to obtain a 3D structure to depths of 1600 km. In the resultant image, we find a characteristic distribution of low- velocity regions. The most prominent features are a large doughnut-shaped low-velocity region at 800 km depth, and an elongated large low-velocity region beneath the Society to Pitcairn hotspots at 1200 km depth. Our model suggests that a large low shear velocity province rooted in the D00 extends upwards and culminates near the top of the lower mantle beneath the central part of the South Pacific Superswell although its perfect continuity is not still confirmed
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