451 research outputs found

    Orbital and physical parameters of eclipsing binaries from the ASAS catalogue -- I. A sample of systems with components' masses between 1 and 2 M_\odot

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    We derive the absolute physical and orbital parameters for a sample of 18 detached eclipsing binaries from the \emph{All Sky Automated Survey} (ASAS) database based on the available photometry and our own radial velocity measurements. The radial velocities (RVs) are computed using spectra we collected with the 3.9-m Anglo-Australian Telescope and its \emph{University College London Echelle Spectrograph} and the 1.9-m SAAO Radcliffe telescope and its \emph{Grating Instrument for Radiation Analysis with a Fibre Fed Echelle}. In order to obtain as precise RVs as possible, most of the systems were observed with an iodine cell available at the AAT/UCLES and/or analyzed using the two-dimensional cross-correlation technique (TODCOR). The RVs were measured with TODCOR using synthetic template spectra as references. However, for two objects we used our own approach to the tomographic disentangling of the binary spectra to provide observed template spectra for the RV measurements and to improve the RV precision even more. For one of these binaries, AI Phe, we were able to the obtain an orbital solution with an RV rmsrms of 62 and 24 m s1^{-1} for the primary and secondary respectively. For this system, the precision in Msin3iM \sin^3{i} is 0.08%. For the analysis, we used the photometry available in the ASAS database. We combined the RV and light curves using PHOEBE and JKTEBOP codes to obtain the absolute physical parameters of the systems. Having precise RVs we were able to reach \sim0.2 % precision (or better) in masses in several cases but in radii, due to the limited precision of the ASAS photometry, we were able to reach a precision of only 1% in one case and 3-5 % in a few more cases. For the majority of our objects, the orbital and physical analysis is presented for the first time.Comment: 16 pages, 2 figures, 6 tables in the main text, 1 table in appendix, to appear in MNRA

    Archival light curves from the Bamberg Sky Patrol - CFOctantis, 1964-1976

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    We use the archive of the Bamberg Sky Patrol to obtain light curves of the active K subgiant CF Octantis for the interval 1964-1976. Digitised images of the field near CF Oct were obtained with a flat-bed scanner. Aperture photometry was performed of photo-positives of these images. Using a transformation to second order in plate magnitude, and first order in B-V, for 9 field stars for each plate, the B magnitudes of CF Octantis were obtained for just over 350 plates. The estimated precision of an individual determination of the B magnitude of CF Oct is 0.05 mag. Analysis of the resulting data reveals the known 20 d rotational variation of this star, and shows the evolution of the light curves from year to year. We obtain light curves with good phase coverage for 1964 to 1969 inclusive, partial light curves for 1970 and 1976, and a few data points from 1971. The amplitude of variation ranges from ~0.2 to \~0.4 mag. There is evidence that the characteristic rotation period of the star in the 1960s was slightly less than that measured from photoelectric photometry in the 1980s.Comment: 11 pages, 11 figures, accepted for publication in MNRA

    Moral emotions and moral disengagement: concurrent and longitudinal associations with aggressive behavior among early adolescents

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    The complex temporal associations among moral disengagement, moral emotions, and aggressive behavior were investigated within a short-term four-wave longitudinal study in a sample of early adolescents (at T1: N = 245; Mage= 12.16 years; SD = 0.85). Moral disengagement and aggressive behavior were investigated by validated self-report scales. Shame and guilt were assessed in response to six-story vignettes. A series of four-wave longitudinal mediation analyses were conducted to test several theoretically meaningful models. Mediation models revealed positive reciprocal longitudinal effects between aggressive behavior and moral disengagement. Aggressive behavior negatively predicted moral emotions, and moral disengagement was negatively associated with moral emotions over time. When testing competing models including all three variables in one model, no theoretical meaningful mediation process emerged: Instead, high moral disengagement predicted lower moral emotions but higher aggressive behavior over time. Results are discussed regarding their practical importance for prevention and intervention programs

    Lipoprotein ability to exchange and remove lipids from model membranes as a function of fatty acid saturation and presence of cholesterol

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    Lipoproteins play a central role in the development of atherosclerosis. High and low-density lipoproteins (HDL and LDL), known as 'good' and 'bad' cholesterol, respectively, remove and/or deposit lipids into the artery wall. Hence, insight into lipid exchange processes between lipoproteins and cell membranes is of particular importance in understanding the onset and development of cardiovascular disease. In order to elucidate the impact of phospholipid tail saturation and the presence of cholesterol in cell membranes on these processes, neutron reflection was employed in the present investigation to follow lipid exchange with both HDL and LDL against model membranes. Mirroring clinical risk factors for the development of atherosclerosis, lower exchange was observed in the presence of cholesterol, as well as for an unsaturated phospholipid, compared to faster exchange when using a fully saturated phospholipid. These results highlight the importance of membrane composition on the interaction with lipoproteins, chiefly the saturation level of the lipids and presence of cholesterol, and provide novel insight into factors of importance for build-up and reversibility of atherosclerotic plaque. In addition, the correlation between the results and well-established clinical risk factors suggests that the approach taken can be employed also for understanding a broader set of risk factors including, e.g., effects of triglycerides and oxidative stress, as well as local effects of drugs on atherosclerotic plaque formation

    An Integrated Ecosystem Approach for Assessing the Potential Role of Cultivated Bivalve Shells as Part of the Carbon Trading System

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    The role of bivalve mariculture in the CO2 cycle has been commonly evaluated as the balance between respiration, shell calcium carbonate sequestration and CO2 release during biogenic calcification. However, this approach neglects the ecosystem implications of cultivating bivalves at high densities, e.g. the impact on phytoplankton dynamics and benthic-pelagic coupling, which can significantly contribute to the CO2 cycle. Therefore, an ecosystem approach that accounts for the trophic interactions of bivalve aquaculture, including dissolved and particulate organic and inorganic carbon cycling, is needed to provide a rigorous assessment of the role of bivalve mariculture in the CO2 cycle. On the other hand, the discussion about the inclusion of shells of cultured bivalves into the carbon trading system should be framed within the context of ecosystem goods and services. Humans culture bivalves with the aim of producing food, not sequestering CO2 in their shells, therefore the main ecosystem good provided by bivalve aquaculture is meat production, and shells should be considered as by-products of this human activity. This reasoning provides justification for dividing up respired CO2 between meat and shell when constructing a specific bivalve CO2 budget for potential use of bivalve shells in the carbon trading system. Thus, an integrated ecosystem approach, as well as an understanding of the ecosystems goods and services of bivalve aquaculture, are 2 essential requisites for providing a reliable assessment of the role of bivalve shells in the CO2 cycle

    Strong Decays of Strange Quarkonia

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    In this paper we evaluate strong decay amplitudes and partial widths of strange mesons (strangeonia and kaonia) in the 3P0 decay model. We give numerical results for all energetically allowed open-flavor two-body decay modes of all nsbar and ssbar strange mesons in the 1S, 2S, 3S, 1P, 2P, 1D and 1F multiplets, comprising strong decays of a total of 43 resonances into 525 two-body modes, with 891 numerically evaluated amplitudes. This set of resonances includes all strange qqbar states with allowed strong decays expected in the quark model up to ca. 2.2 GeV. We use standard nonrelativistic quark model SHO wavefunctions to evaluate these amplitudes, and quote numerical results for all amplitudes present in each decay mode. We also discuss the status of the associated experimental candidates, and note which states and decay modes would be especially interesting for future experimental study at hadronic, e+e- and photoproduction facilities. These results should also be useful in distinguishing conventional quark model mesons from exotica such as glueballs and hybrids through their strong decays.Comment: 69 pages, 5 figures, 39 table

    Next Steps for Human-Computer Integration

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    Human-Computer Integration (HInt) is an emerging paradigm in which computational and human systems are closely interwoven. Integrating computers with the human body is not new. however, we believe that with rapid technological advancements, increasing real-world deployments, and growing ethical and societal implications, it is critical to identify an agenda for future research. We present a set of challenges for HInt research, formulated over the course of a five-day workshop consisting of 29 experts who have designed, deployed and studied HInt systems. This agenda aims to guide researchers in a structured way towards a more coordinated and conscientious future of human-computer integration

    Comparing nuclear power trajectories in Germany and the UK: from ‘regimes' to ‘democracies’ in sociotechnical transitions and Discontinuities

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    This paper focuses on arguably the single most striking contrast in contemporary major energy politics in Europe (and even the developed world as a whole): the starkly differing civil nuclear policies of Germany and the UK. Germany is seeking entirely to phase out nuclear power by 2022. Yet the UK advocates a ‘nuclear renaissance’, promoting the most ambitious new nuclear construction programme in Western Europe.Here,this paper poses a simple yet quite fundamental question: what are the particular divergent conditions most strongly implicated in the contrasting developments in these two countries. With nuclear playing such an iconic role in historical discussions over technological continuity and transformation, answering this may assist in wider understandings of sociotechnical incumbency and discontinuity in the burgeoning field of‘sustainability transitions’. To this end, an ‘abductive’ approach is taken: deploying nine potentially relevant criteria for understanding the different directions pursued in Germany and the UK. Together constituted by 30 parameters spanning literatures related to socio-technical regimes in general as well as nuclear technology in particular, the criteria are divided into those that are ‘internal’ and ‘external’ to the ‘focal regime configuration’ of nuclear power and associated ‘challenger technologies’ like renewables. It is ‘internal’ criteria that are emphasised in conventional sociotechnical regime theory, with ‘external’ criteria relatively less well explored. Asking under each criterion whether attempted discontinuation of nuclear power would be more likely in Germany or the UK, a clear picture emerges. ‘Internal’ criteria suggest attempted nuclear discontinuation should be more likely in the UK than in Germany– the reverse of what is occurring. ‘External’ criteria are more aligned with observed dynamics –especially those relating to military nuclear commitments and broader ‘qualities of democracy’. Despite many differences of framing concerning exactly what constitutes ‘democracy’, a rich political science literature on this point is unanimous in characterising Germany more positively than the UK. Although based only on a single case,a potentially important question is nonetheless raised as to whether sociotechnical regime theory might usefully give greater attention to the general importance of various aspects of democracy in constituting conditions for significant technological discontinuities and transformations. If so, the policy implications are significant. A number of important areas are identified for future research, including the roles of diverse understandings and specific aspects of democracy and the particular relevance of military nuclear commitments– whose under-discussion in civil nuclear policy literatures raises its own questions of democratic accountability

    Adipose-tissue-derived therapeutic cells in their natural environment as an autologous cell therapy strategy: the microtissue-stromal vascular fraction

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    The prerequisite for a successful clinical use of autologous adipose-tissue-derived cells is the highest possible regenerative potential of the applied cell population, the stromal vascular fraction (SVF). Current isolation methods depend on high enzyme concentration, lysis buffer, long incubation steps and mechanical stress, resulting in single cell dissociation. The aim of the study was to limit cell manipulation and obtain a derivative comprising therapeutic cells (microtissue-SVF) without dissociation from their natural extracellular matrix, by employing a gentle good manufacturing practice (GMP)-grade isolation. The microtissue-SVF yielded larger numbers of viable cells as compared to the improved standard-SVF, both with low enzyme concentration and minimal dead cell content. It comprised stromal tissue compounds (collagen, glycosaminoglycans, fibroblasts), capillaries and vessel structures (CD31+, smooth muscle actin+). A broad range of cell types was identified by surface-marker characterisation, including mesenchymal, haematopoietic, pericytic, blood and lymphatic vascular and epithelial cells. Subpopulations such as supra-adventitial adipose-derived stromal/stem cells and endothelial progenitor cells were significantly more abundant in the microtissue-SVF, corroborated by significantly higher potency for angiogenic tube-like structure formation in vitro. The microtissue-SVF showed the characteristic phenotype and tri-lineage mesenchymal differentiation potential in vitro and an immunomodulatory and pro-angiogenic secretome. In vivo implantation of the microtissue-SVF combined with fat demonstrated successful graft integration in nude mice. The present study demonstrated a fast and gentle isolation by minor manipulation of liposuction material, achieving a therapeutically relevant cell population with high vascularisation potential and immunomodulatory properties still embedded in a fraction of its original matrix

    Ecto-5′-nucleotidase and intestinal ion secretion by enteropathogenic Escherichia coli

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    Enteropathogenic Escherichia coli (EPEC) triggers a large release of adenosine triphosphate (ATP) from host intestinal cells and the extracellular ATP is broken down to adenosine diphosphate (ADP), AMP, and adenosine. Adenosine is a potent secretagogue in the small and large intestine. We suspected that ecto-5′-nucleotidase (CD73, an intestinal enzyme) was a critical enzyme involved in the conversion of AMP to adenosine and in the pathogenesis of EPEC diarrhea. We developed a nonradioactive method for measuring ecto-5′-nucleotidase in cultured T84 cell monolayers based on the detection of phosphate release from 5′-AMP. EPEC infection triggered a release of ecto-5′-nucleotidase from the cell surface into the supernatant medium. EPEC-induced 5′-nucleotidase release was not correlated with host cell death but instead with activation of phosphatidylinositol-specific phospholipase C (PI-PLC). Ecto-5′-nucleotidase was susceptible to inhibition by zinc acetate and by α,β-methylene-adenosine diphosphate (α,β-methylene-ADP). In the Ussing chamber, these inhibitors could reverse the chloride secretory responses triggered by 5′-AMP. In addition, α,β-methylene-ADP and zinc blocked the ability of 5′-AMP to stimulate EPEC growth under nutrient-limited conditions in vitro. Ecto-5′-nucleotidase appears to be the major enzyme responsible for generation of adenosine from adenine nucleotides in the T84 cell line, and inhibitors of ecto-5′-nucleotidase, such as α,β-methylene-ADP and zinc, might be useful for treatment of the watery diarrhea produced by EPEC infection
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