6,692 research outputs found

    Gravity-mode period spacings as seismic diagnostic for a sample of gamma Doradus stars from Kepler space photometry and high-resolution ground-based spectroscopy

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    Gamma Doradus stars (hereafter gamma Dor stars) are gravity-mode pulsators of spectral type A or F. Such modes probe the deep stellar interior, offering a detailed fingerprint of their structure. Four-year high-precision space-based Kepler photometry of gamma Dor stars has become available, allowing us to study these stars with unprecedented detail. We selected, analysed, and characterized a sample of 67 gamma Dor stars for which we have Kepler observations available. For all the targets in the sample we assembled high-resolution spectroscopy to confirm their F-type nature. We found fourteen binaries, among which four single-lined binaries, five double-lined binaries, two triple systems and three binaries with no detected radial velocity variations. We estimated the orbital parameters whenever possible. For the single stars and the single-lined binaries, fundamental parameter values were determined from spectroscopy. We searched for period spacing patterns in the photometric data and identified this diagnostic for 50 of the stars in the sample, 46 of which are single stars or single-lined binaries. We found a strong correlation between the spectroscopic vsini and the period spacing values, confirming the influence of rotation on gamma Dor-type pulsations as predicted by theory. We also found relations between the dominant g-mode frequency, the longest pulsation period detected in series of prograde modes, vsini, and log Teff.Comment: 61 pages, 61 figures, 6 tables, accepted for publication in ApJ

    Molecular misreading: The occurrence of frameshift proteins in different diseases

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    Neuronal homoeostasis requires a constant balance between biosynthetic and catabolic processes. Eukaryotic cells primarily use two distinct mechanisms for degradation: the proteasome and autophagy of aggregates by the lysosomes. We focused on the UPS (ubiquitin-proteasome system). As a result of molecular misreading, misframed UBB (ubiquitin B) (UBB+1) is generated. UBB+1 accumulates in the neuritic plaques and neurofibrillary tangles in all patients with AD (Alzheimer's disease) and in the neuronal and glial hallmarks of other tauopathies and in polyglutamine diseases such as Huntington's disease. UBB+1 is not present in synucleinopathies such as Parkinson's disease. We showed that UBB+1 causes UPS dysfunction, aggregation and apoptotic cell death. UBB+1 is also present in non-neurological cells, hepatocytes of the diseased liver and in muscles during inclusion body myositis. Other frequently occurring (age-related) diseases such as Type 2 (non-insulin-dependent) diabetes mellitus are currently under investigation. These findings point to the importance of the UPS in diseases and open new avenues for target identification of the main players of the UPS. Treatment of these diseases with tools (e.g. viral RNA interference constructs) to intervene with specific targets is the next step

    Transitions in wheat endosperm metabolism upon transcriptional induction of oil accumulation by oat endosperm WRINKLED1

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    Background: Cereal grains, including wheat (Triticum aestivum L.), are major sources of food and feed, with wheat being dominant in temperate zones. These end uses exploit the storage reserves in the starchy endosperm of the grain, with starch being the major storage component in most cereal species. However, oats (Avena sativa L.) differs in that the starchy endosperm stores significant amounts of oil. Understanding the control of carbon allocation between groups of storage compounds, such as starch and oil, is therefore important for understanding the composition and hence end use quality of cereals. WRINKLED1 is a transcription factor known to induce triacylglycerol (TAG; oil) accumulation in several plant storage tissues. Results: An oat endosperm homolog of WRI1 (AsWRI1) expressed from the endosperm-specific HMW1Dx5 promoter resulted in drastic changes in carbon allocation in wheat grains, with reduced seed weight and a wrinkled seed phenotype. The starch content of mature grain endosperms of AsWRI1-wheat was reduced compared to controls (from 62 to 22% by dry weight (dw)), TAG was increased by up to nine-fold (from 0.7 to 6.4% oil by dw) and sucrose from 1.5 to 10% by dw. Expression of AsWRI1 in wheat grains also resulted in multiple layers of elongated peripheral aleurone cells. RNA-sequencing, lipid analyses, and pulse-chase experiments using 14C-sucrose indicated that futile cycling of fatty acids could be a limitation for oil accumulation. Conclusions: Our data show that expression of oat endosperm WRI1 in the wheat endosperm results in changes in metabolism which could underpin the application of biotechnology to manipulate grain composition. In particular, the striking effect on starch synthesis in the wheat endosperm indicates that an important indirect role of WRI1 is to divert carbon allocation away from starch biosynthesis in plant storage tissues that accumulate oil

    Synthesis and Optimization of Reversible Circuits - A Survey

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    Reversible logic circuits have been historically motivated by theoretical research in low-power electronics as well as practical improvement of bit-manipulation transforms in cryptography and computer graphics. Recently, reversible circuits have attracted interest as components of quantum algorithms, as well as in photonic and nano-computing technologies where some switching devices offer no signal gain. Research in generating reversible logic distinguishes between circuit synthesis, post-synthesis optimization, and technology mapping. In this survey, we review algorithmic paradigms --- search-based, cycle-based, transformation-based, and BDD-based --- as well as specific algorithms for reversible synthesis, both exact and heuristic. We conclude the survey by outlining key open challenges in synthesis of reversible and quantum logic, as well as most common misconceptions.Comment: 34 pages, 15 figures, 2 table

    On some nonlinear extensions of the angular momentum algebra

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    Deformations of the Lie algebras so(4), so(3,1), and e(3) that leave their so(3) subalgebra undeformed and preserve their coset structure are considered. It is shown that such deformed algebras are associative for any choice of the deformation parameters. Their Casimir operators are obtained and some of their unitary irreducible representations are constructed. For vanishing deformation, the latter go over into those of the corresponding Lie algebras that contain each of the so(3) unitary irreducible representations at most once. It is also proved that similar deformations of the Lie algebras su(3), sl(3,R), and of the semidirect sum of an abelian algebra t(5) and so(3) do not lead to associative algebras.Comment: 22 pages, plain TeX + preprint.sty, no figures, to appear in J.Phys.

    Biopolymer-based structuring of liquid oil into soft solids and oleogels using water-continuous emulsions as templates

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    Physical trapping of a hydrophobic liquid oil in a matrix of water-soluble biopolymers was achieved using a facile two-step process by first formulating a surfactant-free oil-in-water emulsion stabilized by biopolymers (a protein and a polysaccharide) followed by complete removal of the water phase (by either high- or low-temperature drying of the emulsion) resulting in structured solid systems containing a high concentration of liquid oil (above 97 wt %). The microstructure of these systems was revealed by confocal and cryo-scanning electron microscopy, and the effect of biopolymer concentrations on the consistency of emulsions as well as the dried product was evaluated using a combination of small-amplitude oscillatory shear rheometry and large deformation fracture studies. The oleogel prepared by shearing the dried product showed a high gel strength as well as a certain degree of thixotropic recovery even at high temperatures. Moreover, the reversibility of the process was demonstrated by shearing the dried product in the presence of water to obtain reconstituted emulsions with rheological properties comparable to those of the fresh emulsion

    The Rise of Cohabitation in the Southern Cone

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    This chapter analyses the increase in cohabitation in the Southern Cone (Argentina, Chile and Uruguay) and attempts to determine the extent to which consensual unions and marriages have similar traits or differ in the context of the cohabitation boom (Esteve et al. 2012). The first section of the chapter reviews the historical context of cohabitation in the Southern Cone. The second section uses census and survey data to analyse the trends in conjugal union formation in the three countries during the last 40 years. We analyse the patterns of both childbearing and union formation, as well as the differences between marriage and cohabitation based on educational attainment, labour market participation and household structure. The purpose of this analysis is to better understand whether the behaviour of married and cohabiting women with different characteristics are converging or diverging over time and tentatively, whether more egalitarian gender relationships are emerging in both types of conjugal unions

    Dynamic orifice area variations in functional mitral regurgitation: In vivoreproduction and mechanistic insights

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    Aims: The spinocerebellar ataxia type 2 (SCA2), type 3 (SCA3) and type 7 (SCA7) are clinically characterized by progressive and severe ataxic symptoms, dysarthria, dysphagia, oculomotor impairments, pyramidal and extrapyramidal manifestations and sensory deficits. Although recent clinical studies reported additional disease signs suggesting involvement of the brainstem auditory system, this has never been studied in detail in SCA2, SCA3 or SCA7. Methods: We performed a detailed pathoanatomical investigation of unconventionally thick tissue sections through the auditory brainstem nuclei (that is, nucleus of the inferior colliculus, nuclei of the lateral lemniscus, superior olive, cochlear nuclei) and auditory brainstem fibre tracts (that is, lateral lemniscus, trapezoid body, dorsal acoustic stria, cochlear portion of the vestibulocochlear nerve) of clinically diagnosed and genetically confirmed SCA2, SCA3 and SCA7 patients. Results: Examination of unconventionally thick serial brainstem sections stained for lipofuscin pigment and Nissl material revealed a consistent and widespread involvement of the auditory brainstem nuclei in the SCA2, SCA3 and SCA7 patients studied. Serial brainstem tissue sections stained for myelin showed loss of myelinated fibres in two of the auditory brainstem fibre tracts (that is, lateral lemniscus, trapezoid body) in a subset of patients. Conclusions: The involvement of the auditory brainstem system offers plausible explanations for the auditory impairments detected in some of our and other SCA2, SCA3 and SCA7 patients upon bedside examination or neurophysiological investigation. However, further clinical studies are required to resolve the striking discrepancy between the consistent involvement of the brainstem auditory system observed in this study and the comparatively low frequency of reported auditory impairments in SCA2, SCA3 and SCA7 patients
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