746,237 research outputs found

    The evolution of resistance through costly acquired immunity

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    We examine the evolutionary dynamics of resistance to parasites through acquired immunity. Resistance can be achieved through the innate mechanisms of avoidance of infection and reduced pathogenicity once infected, through recovery from infection and through remaining immune to infection: acquired immunity. We assume that each of these mechanisms is costly to the host and find that the evolutionary dynamics of innate immunity in hosts that also have acquired immunity are quantitatively the same as in hosts that possess only innate immunity. However, compared with resistance through avoidance or recovery, there is less likely to be polymorphism in the length of acquired immunity within populations. Long-lived organisms that can recover at intermediate rates faced with fast-transmitting pathogens that cause intermediate pathogenicity (mortality of infected individuals) are most likely to evolve long-lived acquired immunity. Our work emphasizes that because whether or not acquired immunity is beneficial depends on the characteristics of the disease, organisms may be selected to only develop acquired immunity to some of the diseases that they encounter

    Resource Bounded Immunity and Simplicity

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    Revisiting the thirty years-old notions of resource-bounded immunity and simplicity, we investigate the structural characteristics of various immunity notions: strong immunity, almost immunity, and hyperimmunity as well as their corresponding simplicity notions. We also study limited immunity and simplicity, called k-immunity and feasible k-immunity, and their simplicity notions. Finally, we propose the k-immune hypothesis as a working hypothesis that guarantees the existence of simple sets in NP.Comment: This is a complete version of the conference paper that appeared in the Proceedings of the 3rd IFIP International Conference on Theoretical Computer Science, Kluwer Academic Publishers, pp.81-95, Toulouse, France, August 23-26, 200

    Plain Reading, Subtle Meaning: Rethinking the IOIA and the Immunity of International Organizations

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    Immunity is freedom from liability, and as such, it can quite literally provide a “get out of jail free” card. In the United States, international organizations face uncertainty about the scope of their immunity, which is provided by the International Organizations Immunities Act (IOIA). The D.C. Circuit has found that international organizations enjoy absolute immunity under the IOIA. Conversely, the Third Circuit recently held that international organizations are only entitled to restrictive immunity, which limits immunity to claims involving an organization’s public acts and does not exempt them from suits based on their commercial or private conduct. This Note contends that a plain reading of the IOIA, combined with a full understanding of the history and legislative purpose behind the immunity of international organizations, presents a third interpretation. It concludes that the IOIA requires judicial deference to immunity determinations by the executive branch, which provides the flexibility necessary to allow international organizations to operate without undue interference

    Section 1983: Absolute Immunity for Pretrial Police Testimony

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    This Note discusses the development of the Supreme Court\u27s approach to section 1983 immunity for trial witnesses. Central to this discussion is an overview of the history of common-law immunities for government officials, the history and purpose of section 1983, and the history of the Supreme Court\u27s section 1983 immunity decisions. The author discusses the current disagreement in the circuits over extending section 1983 immunity to pretrial police testimony. The author also analyzes various possible answers to the question of whether to extend witness immunity under section 1983 to specific pretrial proceedings by applying the current Supreme Court functional categories immunity analysis and the policies for and against extension of absolute immunity to pretrial police testimony. The Note concludes that police officers should enjoy absolute immunity from section 1983 suits that are based solely on their perjured pretrial testimony. However, the author also suggests that a section 1983 plaintiff should be allowed to introduce such testimony as evidence that a police officer initiated a baseless or malicious prosecution against the plaintiff

    \u3ci\u3eAltmann v. Austria\u3c/i\u3e and the Retroactivity of the Foreign Sovereign Immunities Act

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    In Republic of Austria v. Altmann, the U.S. Supreme Court decided that the Foreign Sovereign Immunities Act of 1976 (FSIA) generally applies to claims based on events that occurred before the Statute\u27s enactment. To decide the retroactivity question, the Court had occasion to consider the essential nature of foreign sovereign immunity: is it merely a procedural immunity providing foreign states with present protection from the inconvenience and indignity of a lawsuit, or is it something more than that? The Court\u27s examination of this question was brief and unsatisfying. Its analysis would have been enriched by a recognition that foreign sovereign immunity is regulated not just by federal statute, but also by principles of customary international law that the federal statute sought, in large part, to codify. Among the authorities the Court did consider, it found support for the proposition that foreign sovereign immunity is a procedural immunity and also for the proposition that foreign sovereign immunity is an immunity from substantive liability. Viewing these authorities as contradictory, the Court concluded that the retroactivity issue had to be resolved on other grounds. This brief article maintains that the relevant authorities are not contradictory. They are consistent with the conclusion that foreign states enjoy both a procedural and a substantive immunity, a possibility that the Court appears to have overlooked

    Modeling the long term dynamics of pre-vaccination pertussis

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    The dynamics of strongly immunizing childhood infections is still not well understood. Although reports of successful modeling of several incidence data records can be found in the literature, the key determinants of the observed temporal patterns have not been clearly identified. In particular, different models of immunity waning and degree of protection applied to disease and vaccine induced immunity have been debated in the literature on pertussis. Here we study the effect of disease acquired immunity on the long term patterns of pertussis prevalence. We compare five minimal models, all of which are stochastic, seasonally forced, well-mixed models of infection based on susceptible-infective-recovered dynamics in a closed population. These models reflect different assumptions about the immune response of naive hosts, namely total permanent immunity, immunity waning, immunity waning together with immunity boosting, reinfection of recovered, and repeat infection after partial immunity waning. The power spectra of the output prevalence time series characterize the long term dynamics of the models. For epidemiological parameters consistent with published data for pertussis, the power spectra show quantitative and even qualitative differences that can be used to test their assumptions by comparison with ensembles of several decades long pre-vaccination data records. We illustrate this strategy on two publicly available historical data sets.Comment: paper (31 pages, 11 figures, 1 table) and supplementary material (19 pages, 5 figures, 2 tables

    Sovereign Immunity

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