556 research outputs found

    Extreme geomagnetic disturbances due to shocks within CMEs

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    We report on features of solar wind-magnetosphere coupling elicited by shocks propagating through coronal mass ejections (CMEs) by analyzing the intense geomagnetic storm of 6 August 1998. During this event, the dynamic pressure enhancement at the shock combined with a simultaneous increase in the southward component of the magnetic field resulted in a large earthward retreat of Earth\u27s magnetopause, which remained close to geosynchronous orbit for more than 4ā€‰h. This occurred despite the fact that both shock and CME were weak and relatively slow. Another similar example of a weak shock inside a slow CME resulting in an intense geomagnetic storm is the 30 September 2012 event, which strongly depleted the outer radiation belt. We discuss the potential of shocks inside CMEs to cause large geomagnetic effects at Earth, including magnetopause shadowing

    Control-Flow Integrity for Real-Time Embedded Systems

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    Attacks on real-time embedded systems can endanger lives and critical infrastructure. Despite this, techniques for securing embedded systems software have not been widely studied. Many existing security techniques for general-purpose computers rely on assumptions that do not hold in the embedded case. This paper focuses on one such technique, control-flow integrity (CFI), that has been vetted as an effective countermeasure against control-flow hijacking attacks on general-purpose computing systems. Without the process isolation and fine-grained memory protections provided by a general-purpose computer with a rich operating system, CFI cannot provide any security guarantees. This work proposes RECFISH, a system for providing CFI guarantees on ARM Cortex-R devices running minimal real-time operating systems. We provide techniques for protecting runtime structures, isolating processes, and instrumenting compiled ARM binaries with CFI protection. We empirically evaluate RECFISH and its performance implications for real-time systems. Our results suggest RECFISH can be directly applied to binaries without compromising real-time performance; in a test of over six million realistic task systems running FreeRTOS, 85% were still schedulable after adding RECFISH

    Capabilitarian Sufficiency: Capabilities and Social Justice

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    This paper suggests an account of sufficientarianismā€”that is, that justice is fulfilled when everyone has enoughā€”laid out within a general framework of the capability approach. In doing so, it seeks to show that sufficiency is especially plausible as an ideal of social justice when constructed around key capabilitarian insights such as freedom, pluralism, and attention to empirical interconnections between central capabilities. Correspondingly, we elaborate on how a framework for evaluating social justice would look when constructed in this way and give reasons for why capabilitarians should embrace sufficientarianism. We do this by elaborating on how capabilitarian values underpin sufficiency. On this basis, we identify three categories of central capabilities; those related to biological and physical needs, those to fundamental interests of a human agent, and those to fundamental interests of a social being. In each category, we argue, achieving sufficiency requires different distributional patterns depending on how the capabilities themselves work and interrelate. This argument adds a new dimension to the way capabilitarians think about social justice and changes how we should target instances of social justice from social-political viewpoint

    Intergenerational justice: a framework for addressing intellectual property rights and climate change

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    At first blush, one may wonder what contribution normative theory can make to what seems to be such a technical/political issue as the role of intellectual property rights (IPRs) in the global climate change regime. There are two answers to this. Firstly, as eloquently put by Joe Bowersox,ā€œ... normative theoryā€¦ can be a powerful diagnostic tool for evaluating public policy; it can act as an altimeter, if you will, that checks the thinness of the theoretical air surrounding a particular policy mountain or molehill, telling us whether there is enough oxygen present to support political life. Sometimes theory may even suggest that we try an alternative, less precipitous policy pass by which to cross to the other side.ā€ Conceptions about justice - can provide a valuable framework in terms of ensuring that policy prescriptions are well directed, particularly given that economic policy discourse can bury ethical assumptions. This broader picture, can provide a valuable point of reference in the highly technical debates relating to intellectual property rights and climate change. A second reason for turning to normative theory is the reality that environmental treaties will not be agreed to without at least overlapping conceptions of fairness. This provides a practical motivation for interrogating more deeply justice discourses involved in the climate change negotiations. To the extent that the current global climate regime is inadequate, shared understandings of justice are a crucial precondition for reforming and making more effective the current climate change regime

    MeV magnetosheath ions energized at the bow shock

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    A causal relationship between midlatitude magnetosheath energetic ions and bow shock magnetic geometry was previously established for ion energy up to 200 keV eāˆ’1 for the May 4, 1998, storm event. This study demonstrates that magnetosheath ions with energies above 200 keV up to 1 MeV simply extend the ion spectrum to form a power law tail. Results of cross-correlation analysis suggest that these ions also come directly from the quasi-parallel bow shock, not the magnetosphere. This is confirmed by a comparison of energetic ion fluxes simultaneously measured in the magnetosheath and at the quasi-parallel bow shock when both regions are likely connected by the magnetic field lines. We suggest that ions are accelerated at the quasi-parallel bow shock to energies as high as 1 MeV and subsequently transported into the magnetosheath during this event

    Which executive functioning deficits are associated with AD/HD, ODD/CD and comorbid AD/HD+ODD/CD?

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    Item does not contain fulltextThis study investigated (1) whether attention deficit/hyperactivity disorder (AD/HD) is associated with executive functioning (EF) deficits while controlling for oppositional defiant disorder/conduct disorder (ODD/CD), (2) whether ODD/CD is associated with EF deficits while controlling for AD/HD, and (3)~whether a combination of AD/HD and ODD/CD is associated with EF deficits (and the possibility that there is no association between EF deficits and AD/HD or ODD/CD in isolation). Subjects were 99~children ages 6ā€“12 years. Three putative domains of EF were investigated using well-validated tests: verbal fluency, working memory, and planning. Independent of ODD/CD, AD/HD was associated with deficits in planning and working memory, but not in verbal fluency. Only teacher rated AD/HD, but not parent rated AD/HD, significantly contributed to the prediction of EF task performance. No EF deficits were associated with ODD/CD. The presence of comorbid AD/HD accounts for the EF deficits in children with comorbid AD/HD+ODD/CD. These results suggest that EF deficits are unique to AD/HD and support the model proposed by R. A. Barkley (1997).17 p

    Individual Rights, Economic Transactions, and Recognition: A Legal Approach to Social Economics

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    Modernity brought the idea of individual property rights as a com- plex phenomenon. However, economics adopted a simplistic view of property as a fundamental institution, understating the complex interaction of different rights and obligations that frame the legal environment of economic processes with an insufficiently elaborated tool. Here, a more elaborate view of legal elements will be propose
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