116 research outputs found

    Complete experimental toolbox for alignment-free quantum communication

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    Quantum communication employs the counter-intuitive features of quantum physics to perform tasks that are im- possible in the classical world. It is crucial for testing the foundations of quantum theory and promises to rev- olutionize our information and communication technolo- gies. However, for two or more parties to execute even the simplest quantum transmission, they must establish, and maintain, a shared reference frame. This introduces a considerable overhead in communication resources, par- ticularly if the parties are in motion or rotating relative to each other. We experimentally demonstrate how to circumvent this problem with the efficient transmission of quantum information encoded in rotationally invariant states of single photons. By developing a complete toolbox for the efficient encoding and decoding of quantum infor- mation in such photonic qubits, we demonstrate the fea- sibility of alignment-free quantum key-distribution, and perform a proof-of-principle alignment-free entanglement distribution and violation of a Bell inequality. Our scheme should find applications in fundamental tests of quantum mechanics and satellite-based quantum communication.Comment: Main manuscript: 7 pages, 3 figures; Supplementary Information: 7 pages, 3 figure

    Abundance analysis of targets for the COROT / MONS asteroseimology missions I. Semi-automatic abundance analysis of the gamma Dor star HD 49434

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    One of the goals of the ground-based support program for the COROT and MONS/Roemer satellite missions is to select and characterise suitable target stars for the part of the missions dedicated to asteroseismology. While the global atmospheric parameters may be determined with good accuracy from the Stromgren indices, careful abundance analysis must be made for the proposed main targets. This is a time consuming process considering the long list of primary and secondary targets. We have therefore developed new software called VWA for this task. The VWA automatically selects the least blended lines from the atomic line database VALD, and consequently adjusts the abundance in order to find the best match between the calculated and observed spectra. The variability of HD 49434 was discovered as part of COROT ground-based support observations. Here we present a detailed abundance analysis of HD 49434 using VWA. For most elements we find abundances somewhat below the Solar values, in particular we find [Fe/H] = -0.13(14). We also present the results from the study of the variability that is seen in spectroscopic and photometric time series observations. From the characteristics of the variation seen in photometry and in the line profiles we propose that HD 49434 is a variable star of the gamma Doradus type.Comment: 10 pages, 6 figure

    Climate change drives microevolution in a wild bird

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    To ensure long-term persistence, organisms must adapt to climate change, but an evolutionary response to a quantified selection pressure driven by climate change has not been empirically demonstrated in a wild population. Here, we show that pheomelanin-based plumage colouration in tawny owls is a highly heritable trait, consistent with a simple Mendelian pattern of brown (dark) dominance over grey (pale). We show that strong viability selection against the brown morph occurs, but only under snow-rich winters. As winter conditions became milder in the last decades, selection against the brown morph diminished. Concurrent with this reduced selection, the frequency of brown morphs increased rapidly in our study population during the last 28 years and nationwide during the last 48 years. Hence, we show the first evidence that recent climate change alters natural selection in a wild population leading to a microevolutionary response, which demonstrates the ability of wild populations to evolve in response to climate change

    Cataclysmic Variables from Sloan Digital Sky Survey V -- the search for period bouncers continues

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    SDSS-V is carrying out a dedicated survey for white dwarfs, single and in binaries, and we report the analysis of the spectroscopy of cataclysmic variables (CVs) and CV candidates obtained during the final plug plate observations of SDSS. We identify eight new CVs, spectroscopically confirm 53 and refute eleven published CV candidates, and we report 21 new or improved orbital periods. Combined with previously published data, the orbital period distribution of the SDSS-V CVs does not clearly exhibit a period gap. This is consistent with previous findings that spectroscopically identified CVs have a larger proportion of short-period systems compared to samples identified from photometric variability. Remarkably, despite a systematic search, we find very few period bouncers. We estimate the space density of period bouncers to be ≃0.2×10−6 pc−3\simeq0.2\times10^{-6}\,\mathrm{pc}^{-3}, i.e. they represent only a few per cent of the total CV population. This suggests that during their final phase of evolution, CVs either destroy the donor, e.g. via a merger, or that they become detached and cease mass transfer.Comment: Submitted to MNRA

    Abundance analysis of targets for the COROT/MONS asteroseismology missions II. Abundance analysis of the COROT main targets

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    One of the goals of the ground-based support program for the COROT and MONS/RØMER satellite missions is to characterize suitable target stars for the part of the missions dedicated to asteroseismology. We present the detailed abundance analysis of nine of the potential COROT main targets using the semi-automatic software VWA. For two additional COROT targets we could not perform the analysis due to the high rotational velocity of these stars. For five stars with low rotational velocity we have also performed abundance analysis by a classical equivalent width method in order to test the reliability of the VWA software. The agreement between the different methods is good. We find that it is necessary to measure abundances extracted from each line relative to the abundances found from a spectrum of the Sun in order to remove systematic errors. We have constrained the global atmospheric parameters Teff log g, and [Fe/H] to within 70-100 K, 0.1-0.2 dex, and 0.1 dex for five stars which are slow rotators (Îœ sin i 60 km s-1) it is not possible to constrain the atmospheric parameters

    Internationalisation in Higher Education as a catalyst to STEAM

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    Internationalisation efforts in Higher Education are usually led by the institutions' International Offices in partnership with the academic units at various levels, thus providing an ideal opportunity to promote collaboration across colleges, schools and departments, and to bring staff with a broad range of experience and expertise to work together. This chapter discusses two ways in which Higher Education institutions can take advantage of these internationalisation efforts to cultivate and nurture STEAM. First, considering internationalisation of the curriculum (IoC) across disciplines, which entails the incorporation of 'an intercultural dimension into the content of the curriculum as well as the teaching and learning processes and support services of a programme of study' (Leask 2015). Inasmuch as IoC seeks to develop students' international and intercultural perspectives as global professionals and citizens, it requires engagement with the arts, humanities, social sciences and sustainability initiatives across programmes, providing an opportunity to embed STEAM in the curriculum. Further, I argue that there is a parallelism between the national cultures that IoC seeks to draw from and the disciplines themselves, which are also different cultures, 'separate communities of practice with their own organisations, power hierarchies, questions to answer and [sometimes heavily policed] entry boundaries' (Brown and Harris 2014, 115). An interdisciplinary approach, and in particular one that promotes STEAM, should enrich the curriculum and increase its relevance in the same way that an international approach would. And second, through matching an employability and transferable skills training programme across disciplines to the 'internationalisation at home' initiatives that seek to deploy international students and staff as resources in Higher Education institutions (Altbach and Yudkevich 2017). Such a programme would focus on bringing skills traditionally associated with the arts and humanities - such as aesthetic appreciation, critical thinking or communication skills - to students of technology and science, while also bringing skills traditionally associated with science and technology - such as planning and problem solving, numeracy and the use of information technology - to students of arts and humanities, actively taking advantage of the innovative perspectives that international staff and students bring. In sum, the chapter argues that the internationalisation agenda in Higher Education partly inherently overlaps with that of STEAM cultivation, and highlights two practical ways in which curricula can be modified to promote the latter while advancing the former for a more inclusive student experience, enhancing employability skills and promoting the interdisciplinary outlook to the most pressing wicked problems that societies so badly need today

    Genomics and drug profiling of fatal TCF3-HLF-positive acute lymphoblastic leukemia identifies recurrent mutation patterns and therapeutic options.

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    TCF3-HLF-positive acute lymphoblastic leukemia (ALL) is currently incurable. Using an integrated approach, we uncovered distinct mutation, gene expression and drug response profiles in TCF3-HLF-positive and treatment-responsive TCF3-PBX1-positive ALL. We identified recurrent intragenic deletions of PAX5 or VPREB1 in constellation with the fusion of TCF3 and HLF. Moreover somatic mutations in the non-translocated allele of TCF3 and a reduction of PAX5 gene dosage in TCF3-HLF ALL suggest cooperation within a restricted genetic context. The enrichment for stem cell and myeloid features in the TCF3-HLF signature may reflect reprogramming by TCF3-HLF of a lymphoid-committed cell of origin toward a hybrid, drug-resistant hematopoietic state. Drug response profiling of matched patient-derived xenografts revealed a distinct profile for TCF3-HLF ALL with resistance to conventional chemotherapeutics but sensitivity to glucocorticoids, anthracyclines and agents in clinical development. Striking on-target sensitivity was achieved with the BCL2-specific inhibitor venetoclax (ABT-199). This integrated approach thus provides alternative treatment options for this deadly disease

    WIYN Open Cluster Study. XXVI. Improved kinematic membership and spectroscopy of IC 2391

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    [Abridged] Contex. Young open clusters provide important clues to the interface between the main sequence and pre-main-sequence phases of stellar evolution. The young and nearby open cluster IC 2391 is well-suited to studies of these two evolutionary phases. Aims. We establish a bona fide set of cluster members and then analyze this set in terms of binary frequency, projected rotational velocities, [Fe/H], and lithium abundance. In the wake of the Hipparcos distance controversy for the Pleiades, we compare the main-sequence fitting distance modulus to the Hipparcos mean parallax for IC 2391. Results. The proper-motion survey covers a 6 times larger sky area than the prior targeted searches for cluster members in IC 2391. A total of 66 stars are considered bona fide cluster members down to a mass equivalent to 0.5M_sun. A quarter of them have been newly identified with many in the F2-K5 spectral range, which is crucial for a main-sequence fit. We find a mean [Fe/H] value of +0.06+/-0.06, when a solar abundance of log epsilon (Fe)=7.45 is adopted. The main sequence fitting yields a distance modulus that is 0.19 mag larger than that derived from Hipparcos parallaxes; thus this offset nearly has the size of a similar offset found for the Pleiades. The Li abundance pattern is similar to the earlier findings and is typical for a 40 Myr old open cluster.Comment: 18 pages, 11 figures, Astronomy & Astrophysics, in pres
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