8,629 research outputs found

    A proposed neutral line signature

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    An identifying signature is proposed for the existence and location of the neutral line in the magnetotail. The signature, abrupt density, and temperature changes in the Earthtail direction, was first discovered in test particle simulations. Such temperature variations have been observed in ISEE data (Huang et. al. 1992), but their connection to the possible existence of a neutral line in the tail has not yet been established. The proposed signature develops earlier than the ion velocity space ridge of Martin and Speiser (1988), but can only be seen by spacecraft in the vicinity of the neutral line, while the latter can locate a neutral line remotely

    High Sensitivity Search for v_e’s from the Sun and Other Sources at KamLAND

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    Data corresponding to a KamLAND detector exposure of 0.28 kton yr has been used to search for ν̅ _e’s in the energy range 8.3 < E_(ν̅e) < 14.8  MeV. No candidates were found for an expected background of 1.1±0.4 events. This result can be used to obtain a limit on ν̅_e fluxes of any origin. Assuming that all ν̅_e flux has its origin in the Sun and has the characteristic ^8B solar ν_e energy spectrum, we obtain an upper limit of 3.7×10^2  cm^(-2) ^(s-1) (90% C.L.) on the ν̅_e flux. We interpret this limit, corresponding to 2.8×10^(-4) of the standard solar model ^8B ν_e flux, in the framework of spin-flavor precession and neutrino decay models

    Modus Vivendi Beyond the Social Contract: Peace, Justice, and Survival in Realist Political Theory

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    This essay examines the promise of the notion of modus vivendi for realist political theory. I interpret recent theories of modus vivendi as affirming the priority of peace over justice, and explore several ways of making sense of this idea. I proceed to identify two key problems for modus vivendi theory, so conceived. Normatively speaking, it remains unclear how this approach can sustain a realist critique of Rawlsian theorizing about justice while avoiding a Hobbesian endorsement of absolutism. And conceptually, the theory remains wedded to a key feature of social contract theory: political order is conceived as based on agreement. This construes the horizontal tensions among individual or group agents in society as prior to the vertical, authoritative relations between authorities and their subjects. Political authority thereby appears from the start as a solution to societal conflict, rather than a problem in itself. I argue that this way of framing the issue abstracts from political experience. Instead I attempt to rethink the notion of modus vivendi from within the lived experience of political conflict, as oriented not primarily toward peace, but political survival. With this shift of perspective, the idea of modus vivendi shows us, pace Bernard Williams, that the “first political question” is not how to achieve order and stability, but rather: what can I live with

    Cryotherapy of Liver Tumours–A Practical Guide

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    The use of cryotherapy for the treatment of some unresectable liver tumours has been clearly established as a therapeutic option. Intra-operative ultrasound has enhanced the process by enabling the surgeon to identify hepatic lesions and to allow visualisation of the freezing process to ensure that the cryolesion will include the tumour mass. The purpose of this paper is to provide a practical guide to surgeons who wish to perform cryotherapy of liver tumours. Patient selection and anaesthetic considerations are important. The surgeon should be able to deal with the complications of cryotherapy, particularly the intra-operative haemorrhage which may arise from cracking of the hepatic parenchyma as the iceball thaws. Follow-up is based on tumour marker assay and imaging of the liver and repeat cryotherapy can be considered for selected cases

    Remote sensing and geologic studies of the orientale basin region

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    Both visual and near-infrared spectral observations are combined with multispectral imaging to study the Orientale interior and exterior, the Cruger region, Grimaldi Region, the Schiller-Schickard Region, and the Humorum Region of the Moon. It was concluded that anorthosites occur in the Inner Rook Mountains of Orientale, the inner ring of Grimaldi, and the main ring of Humorum. Imaging spectroscopy shows that the entire eastern Inner Rook Mountains are composed of anorthosites. Orientale ejecta are strikingly like the surface materials in the region where Apollo 16 landed. This similarity indicates similar mineralogy, i.e., noritic anorthosite. Thus, Orientile ejecta is more mafic than the Inner Rook Mountains. This situation is also true for the Nectaris, Humorum, and Gramaldi basins. Isolated areas of the Orientale region show the presence of gabbroic rocks, but, in general, Orientale ejecta are noritic anorthosites, which contain much more low-Ca pyroxene than high-Ca pyroxene. Ancient (pre-Orientale) mare volcanism apparently occurred in several areas of the western limb

    Monte Carlo drift correction – quantifying the drift uncertainty of global climate models

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    Global climate models are susceptible to drift, causing spurious trends in output variables. Drift is often corrected using data from a control simulation. However, internal climate variability within the control simulation introduces uncertainty to the drift correction process. To quantify this drift uncertainty, we develop a probabilistic technique: Monte Carlo drift correction (MCDC). MCDC samples the standard error associated with drift in the control time series. We apply MCDC to an ensemble of global climate models from the Coupled Model Intercomparison Project Phase 6 (CMIP6). We find that drift correction partially addresses a problem related to drift: energy leakage. Nevertheless, the energy balance of several models remains suspect. We quantify the drift uncertainty of global quantities associated with the Earth's energy balance and thermal expansion of the ocean. When correcting drift in a cumulatively integrated energy flux, we find that it is preferable to integrate the flux before correcting the drift: an alternative method would be to correct the bias before integrating the flux, but this alternative method amplifies the drift uncertainty. Assuming that drift is linear likely leads to an underestimation of drift uncertainty. Time series with weak trends may be especially susceptible to drift uncertainty: for historical thermosteric sea level rise since the 1850s, the drift uncertainty can range from 3 to 24 mm, which is of comparable magnitude to the impact of omitting volcanic forcing in control simulations. Derived coefficients – such as the ocean's expansion efficiency of heat – can also be susceptible to drift uncertainty. When evaluating and analysing global climate model data that are susceptible to drift, researchers should consider drift uncertainty.</p

    Two-dimensional turbulence in magnetised plasmas

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    In an inhomogeneous magnetised plasma the transport of energy and particles perpendicular to the magnetic field is in general mainly caused by quasi two-dimensional turbulent fluid mixing. The physics of turbulence and structure formation is of ubiquitous importance to every magnetically confined laboratory plasma for experimental or industrial application. Specifically, high temperature plasmas for fusion energy research are also dominated by the properties of this turbulent transport. Self-organisation of turbulent vortices to mesoscopic structures like zonal flows is related to the formation of transport barriers that can significantly enhance the confinement of a fusion plasma. This subject of great importance in research is rarely touched on in introductory plasma physics or continuum dynamics courses. Here a brief tutorial on 2D fluid and plasma turbulence is presented as an introduction to the field, appropriate for inclusion in undergraduate and graduate courses.Comment: This is an author-created, un-copyedited version of an article published in European Journal of Physics. IOP Publishing Ltd is not responsible for any errors or omissions in this version of the manuscript or any version derived from it. The definitive publisher authenticated version is available online at doi: 10.1088/0143-0807/29/5/00
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