4,406 research outputs found

    Adaption of space station technology for lunar operations

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    Space Station Freedom technology will have the potential for numerous applications in an early lunar base program. The benefits of utilizing station technology in such a fashion include reduced development and facility costs for lunar base systems, shorter schedules, and verification of such technology through space station experience. This paper presents an assessment of opportunities for using station technology in a lunar base program, particularly in the lander/ascent vehicles and surface modules

    Whipped oil stabilised by surfactant crystals

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    We describe a protocol for preparing very stable air-in-oil foams starting with a one-phase oil solution of a fatty acid (myristic acid) in high oleic sunflower oil at high temperature. Upon cooling below the solubility limit, a two-phase mixture consisting of fatty acid crystals (length around 50 μm) dispersed in an oil solution at its solubility is formed which, after whipping, coat air bubbles in the foam. Foams which do not drain, coalesce or coarsen may be produced either by increasing the fatty acid concentration at fixed temperature or aerating the mixtures at different temperatures at constant concentration. We prove that molecular fatty acid is not surface-active as no foam is possible in the one-phase region. Once the two-phase region is reached, fatty acid crystals are shown to be surface-active enabling foam formation, and excess crystals serve to gel the continuous oil phase enhancing foam stability. A combination of rheology, X-ray diffraction and pulsed nuclear magnetic resonance is used to characterise the crystals and oil gels formed before aeration. The crystal-stabilised foams are temperature-sensitive, being rendered completely unstable on heating around the melting temperature of the crystals. The findings are extended to a range of vegetable oil foams stabilised by a combination of adsorbed crystals and gelling of the oil phase, which destabilise at different temperatures depending on the composition and type of fatty acid chains in the triglyceride molecules

    The Right of a Paid Surety to Subrogation

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    On the Thom Isomorphism for Groupoid-Equivariant Representable K-Theory

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    This thesis proves a general Thom Isomorphism in groupoid-equivariant KK-theory. Through formalizing a certain pushforward functor, we contextualize the Thom isomorphism to groupoid-equivariant representable K-theory with various support conditions. Additionally, we explicitly verify that a Thom class, determined by pullback of the Bott element via a generalized groupoid homomorphism, coincides with a Thom class defined via equivariant spinor bundles and Clifford multiplication. The tools developed in this thesis are then used to generalize a particularly interesting equivalence of two Thom isomorphisms on TX, for a Riemannian G-manifold X

    Poems to Open Palms: Praise Performance and the State in the Sultanate of Oman

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    This dissertation traces the musical constitution of moral, economic, material, and social relations between rural communities and the state in the Sultanate of Oman. I argue that communities embedded within the authoritarian state hegemony of the Sultanate form and affirm social relations with the state through its embodied proxy, Sultan Qābūs bin Ṣa‘īd Āl Bū Ṣa‘īd, via the reciprocal exchange of state-directed giving and praise poetry responses. The circuit of exchange catalyzes the social production of political legitimacy and ensures continued generous distribution by mythopoetically presenting such cyclicity as resulting from elite and non-elite mutuality. This praise poetry is rendered within two song and dance complexes: al-razḥa, a collective war dance with drumming and antiphonal choral singing, and al-‘āzī, a choral ode with a solo singer, tight poetic structure, and a chorus of responders. Through a close analysis of the content and context of praise poems sung by Arab men’s performance troupes experienced over a year of participant observation fieldwork, I argue that praise poetry is an overlooked site for the construction and negotiation of state political legitimacy. Drawing on heterodox and Gramscian political economy, I show how musical performance operates within broader circuits of exchange by functioning as a site wherein non-market economic logics are fused with moral, performative, and political norms. Instead of simply tracing a circuit of utilitarian exchange (praise for gifts for praise), I focus on the how gifts and their responses reciprocally negotiate social relations between state elites and non-elites. By focusing on the words and actions of non elites as they integrate the various proffered benefits of a distributive state into their own communities, I attempt to complicate standard explanations of Arabian Gulf politics and statecraft. I posit two social mechanisms—one which relates generosity and political legitimacy and one that relates performance with the construction of a moral political community—and then follow them through their operation in social space. By singing praise poetry at celebrations of state distribution, praisers rhetorically render such state gifting as “generosity,” which is deeply tied to good leadership in the Omani context. In addition, praisers simultaneously mythopoetically generate a political community of generous givers and grateful receivers who are linked by relations of history, homeland, religion, and kinship. In this way, praise “opens palms” and induces continued elite distributions. However, unequal gifting is fraught with social hazard and threatens to trap communities in dependency relations with the state. By attending to the pragmatics of performance, however, I argue that razḥa and ‘āzī tacitly address this threat of dependency by performing strength and dignity while simultaneously seeking to redraw the relations of unequal gifting from ones of dependency to ones of mutual obligation—a “moral economy.” This ethnomusicological study is an attempt to show how musical and linguistic performers draw on a wide variety of tacit and explicit economic, moral, political, and communal factors in order to take social action in a context of authoritarian state hegemony

    Research in interactive scene analysis

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    An interactive scene interpretation system (ISIS) was developed as a tool for constructing and experimenting with man-machine and automatic scene analysis methods tailored for particular image domains. A recently developed region analysis subsystem based on the paradigm of Brice and Fennema is described. Using this subsystem a series of experiments was conducted to determine good criteria for initially partitioning a scene into atomic regions and for merging these regions into a final partition of the scene along object boundaries. Semantic (problem-dependent) knowledge is essential for complete, correct partitions of complex real-world scenes. An interactive approach to semantic scene segmentation was developed and demonstrated on both landscape and indoor scenes. This approach provides a reasonable methodology for segmenting scenes that cannot be processed completely automatically, and is a promising basis for a future automatic system. A program is described that can automatically generate strategies for finding specific objects in a scene based on manually designated pictorial examples

    Group A Streptococcus in the Gynecologic Patient

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    Background: Over the past few decades, physicians have been reminded of the potential for serious complications arising from group A streptococcal (GAS) infections. These infections continue to pose a serious threat, primarily because the pathophysiology of these infections is complex. This article reviews some of the features of GAS infections and presents two case reports of GAS pelvic infections in women
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