2,596 research outputs found

    On the origin of the canyon diablo no. 2 and no. 3 meteorites

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    Measurements of helium-3, neon-21, and argon-38 in Canyon Diablo meteorites indicated origin of Canyon Diablo-

    Rare gas evidence for two paired meteorite falls

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    Mass spectroscopic analysis of rare gas contents of two paired meteorite fall

    Ages of Ca-rich achondrites

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    Ages of calcium-rich achondrites determined by study of 27 eucrites and shergottite

    A formulation and analysis of combat games

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    Combat is formulated as a dynamical encounter between two opponents, each of whom has offensive capabilities and objectives. With each opponent is associated a target in the event space in which he endeavors to terminate the combat, thereby winning. If the combat terminates in both target sets simultaneously or in neither, a joint capture or a draw, respectively, is said to occur. Resolution of the encounter is formulated as a combat game; namely, as a pair of competing event-constrained differential games. If exactly one of the players can win, the optimal strategies are determined from a resulting constrained zero-sum differential game. Otherwise the optimal strategies are computed from a resulting non-zero-sum game. Since optimal combat strategies frequencies may not exist, approximate of delta-combat games are also formulated leading to approximate or delta-optimal strategies. To illustrate combat games, an example, called the turret game, is considered. This game may be thought of as a highly simplified model of air combat, yet it is sufficiently complex to exhibit a rich variety of combat behavior, much of which is not found in pursuit-evasion games

    A formulation and analysis of combat games

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    Combat which is formulated as a dynamical encounter between two opponents, each of whom has offensive capabilities and objectives is outlined. A target set is associated with each opponent in the event space in which he endeavors to terminate the combat, thereby winning. If the combat terminates in both target sets simultaneously, or in neither, a joint capture or a draw, respectively, occurs. Resolution of the encounter is formulated as a combat game; as a pair of competing event constrained differential games. If exactly one of the players can win, the optimal strategies are determined from a resulting constrained zero sum differential game. Otherwise the optimal strategies are computed from a resulting nonzero sum game. Since optimal combat strategies may frequently not exist, approximate or delta combat games are also formulated leading to approximate or delta optimal strategies. The turret game is used to illustrate combat games. This game is sufficiently complex to exhibit a rich variety of combat behavior, much of which is not found in pursuit evasion games

    The polio eradication end game: what it means for Europe.

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    Biology of bone sarcomas and new therapeutic developments

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    Bone sarcomas are tumours belonging to the family of mesenchymal tumours and constitute a highly heterogeneous tumour group. The three main bone sarcomas are osteosarcoma, Ewing sarcoma and chondrosarcoma each subdivided in diverse histological entities. They are clinically characterised by a relatively high morbidity and mortality, especially in children and adolescents. Although these tumours are histologically, molecularly and genetically heterogeneous, they share a common involvement of the local microenvironment in their pathogenesis. This review gives a brief overview of their specificities and summarises the main therapeutic advances in the field of bone sarcoma

    Immune environment and osteosarcoma

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    Immune niche with its huge cell diversity including more specifically tumour infiltrating lymphocytes (TILs), tumour-associated macrophages (TAMs) regulate osteosarcoma (OS) microenvironment. TAMs exert differential activities in the tumour development according to their polarisation. Indeed, in oncology, M1-polarised macrophages are considered as anti-tumour effectors, and M2-polarised macrophages are defined as pro-tumour modulators by increasing the neoangiogenic process. TAM density is correlated with tumour cell proliferation, invasion, metastasis and poor prognosis in various epithelial and haematological cancers and in bone metastasis. Similarly, tumour infiltrating lymphocytes play a key role in tumour development by inducing a local tolerant environment favourable for the tumour growth. The present chapter will describe the main roles of the immune system in the pathogenesis of osteosarcoma and the most recent therapeutic development based on its regulation
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