470 research outputs found

    Arendt and political realism: towards a realist account of political judgement

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    This article argues that Hannah Arendt’s thought can offer significant insights on political judgement for realism in political theory. We identify a realist position which emphasises the need to account for how humans judge politically, contra moralist tendencies to limit its exercise to rational standards, but which fails to provide a sufficient conception of its structure and potential. Limited appeals to political judgement render the realist defence of the political elusive, and compromise the endeavour to offer a meaningful alternative to the moralist tendency to displace politics. The potential and limitations of realist discussions on judgement are made visible in relation to proto-realists Judith Shklar and Isaiah Berlin. In seeking to enrich the realist conception of the political, the article introduces the displacement critique found in the neglected Arendtian ‘realism’. It also provides the foundations for a distinctly realist account of political judgement which, we argue, requires elaboration along two dimensions: the social coding of political judgement and the political capacities that help judgement build a suitable political sphere

    The evolution of irradiance detection: melanopsin and the non-visual opsins

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    Circadian rhythms are endogenous 24 h cycles that persist in the absence of external time cues. These rhythms provide an internal representation of day length and optimize physiology and behaviour to the varying demands of the solar cycle. These clocks require daily adjustment to local time and the primary time cue (zeitgeber) used by most vertebrates is the daily change in the amount of environmental light (irradiance) at dawn and dusk, a process termed photoentrainment. Attempts to understand the photoreceptor mechanisms mediating non-image-forming responses to light, such as photoentrainment, have resulted in the discovery of a remarkable array of different photoreceptors and photopigment families, all of which appear to use a basic opsin/vitamin A-based photopigment biochemistry. In non-mammalian vertebrates, specialized photoreceptors are located within the pineal complex, deep brain and dermal melanophores. There is also strong evidence in fish and amphibians for the direct photic regulation of circadian clocks in multiple tissues. By contrast, mammals possess only ocular photoreceptors. However, in addition to the image-forming rods and cones of the retina, there exists a third photoreceptor system based on a subset of melanopsin-expressing photosensitive retinal ganglion cells (pRGCs). In this review, we discuss the range of vertebrate photoreceptors and their opsin photopigments, describe the melanopsin/pRGC system in some detail and then finally consider the molecular evolution and sensory ecology of these non-image-forming photoreceptor systems

    The VLT-FLAMES Tarantula Survey III: A very massive star in apparent isolation from the massive cluster R136

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    VFTS 682 is located in an active star-forming region, at a projected distance of 29 pc from the young massive cluster R136 in the Tarantula Nebula of the Large Magellanic Cloud. It was previously reported as a candidate young stellar object, and more recently spectroscopically revealed as a hydrogen-rich Wolf-Rayet (WN5h) star. Our aim is to obtain the stellar properties, such as its intrinsic luminosity, and to investigate the origin of VFTS 682. To this purpose, we model optical spectra from the VLT-FLAMES Tarantula Survey with the non-LTE stellar atmosphere code CMFGEN, as well as the spectral energy distribution from complementary optical and infrared photometry. We find the extinction properties to be highly peculiar (RV ~4.7), and obtain a surprisingly high luminosity log(L/Lsun) = 6.5 \pm 0.2, corresponding to a present-day mass of ~150Msun. The high effective temperature of 52.2 \pm 2.5kK might be explained by chemically homogeneous evolution - suggested to be the key process in the path towards long gamma-ray bursts. Lightcurves of the object show variability at the 10% level on a timescale of years. Such changes are unprecedented for classical Wolf-Rayet stars, and are more reminiscent of Luminous Blue Variables. Finally, we discuss two possibilities for the origin of VFTS 682: (i) the star either formed in situ, which would have profound implications for the formation mechanism of massive stars, or (ii) VFTS 682 is a slow runaway star that originated from the dense cluster R136, which would make it the most massive runaway known to date.Comment: 5 pages, 5 figures, accepted by A&A Letter

    Realism, Liberalism and Non-ideal Theory Or, Are there Two Ways to do Realistic Political Theory?

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    The charge that contemporary political theory has lost touch with the realities of politics is common to both the recent ideal/non-ideal theory debate and the revival of interest in realist thought. However, a tendency has arisen to subsume political realism within the ideal/non-ideal theory debate, or to elide realism with non-ideal theorising. This article argues that this is a mistake. The ideal/non-ideal theory discussion is a methodological debate that takes place within the framework of liberal theory. Realism, contrary to several interpretations, is a distinct and competing conception of politics in its own right that stands in contrast to that of liberal theory. While the two debates are united in a sense that contemporary liberal theory needs to be more realistic, they differ significantly in their understanding of this shortcoming and, more importantly, what it is to do more realistic political theory

    The Evolution of Compact Binary Star Systems

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    We review the formation and evolution of compact binary stars consisting of white dwarfs (WDs), neutron stars (NSs), and black holes (BHs). Binary NSs and BHs are thought to be the primary astrophysical sources of gravitational waves (GWs) within the frequency band of ground-based detectors, while compact binaries of WDs are important sources of GWs at lower frequencies to be covered by space interferometers (LISA). Major uncertainties in the current understanding of properties of NSs and BHs most relevant to the GW studies are discussed, including the treatment of the natal kicks which compact stellar remnants acquire during the core collapse of massive stars and the common envelope phase of binary evolution. We discuss the coalescence rates of binary NSs and BHs and prospects for their detections, the formation and evolution of binary WDs and their observational manifestations. Special attention is given to AM CVn-stars -- compact binaries in which the Roche lobe is filled by another WD or a low-mass partially degenerate helium-star, as these stars are thought to be the best LISA verification binary GW sources.Comment: 105 pages, 18 figure

    Ringer's lactate improves liver recovery in a murine model of acetaminophen toxicity

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    <p>Abstract</p> <p>Background</p> <p>Acetaminophen (APAP) overdose induces massive hepatocyte necrosis. Liver regeneration is a vital process for survival after a toxic insult. Since hepatocytes are mostly in a quiescent state (G<sub>0</sub>), the regeneration process requires the priming of hepatocytes by cytokines such as TNF-α and IL-6. Ringer's lactate solution (RLS) has been shown to increase serum TNF-α and IL-6 in patients and experimental animals; in addition, RLS also provides lactate, which can be used as an alternative metabolic fuel to meet the higher energy demand by liver regeneration. Therefore, we tested whether RLS therapy improves liver recovery after APAP overdose.</p> <p>Methods</p> <p>C57BL/6 male mice were intraperitoneally injected with a single dose of APAP (300 mg/kg dissolved in 1 mL sterile saline). Following 2 hrs of APAP challenge, the mice were given 1 mL RLS or Saline treatment every 12 hours for a total of 72 hours.</p> <p>Results</p> <p>72 hrs after APAP challenge, compared to saline-treated group, RLS treatment significantly lowered serum transaminases (ALT/AST) and improved liver recovery seen in histopathology. This beneficial effect was associated with increased hepatic tissue TNF-α concentration, enhanced hepatic NF-κB DNA binding and increased expression of cell cycle protein cyclin D1, three important factors in liver regeneration.</p> <p>Conclusion</p> <p>RLS improves liver recovery from APAP hepatotoxicity.</p
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