28,667 research outputs found

    Development of thermally stable phosphonitrile elastomers for advanced aerospace structures

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    Attempts to prepare low molecular weight, curable poly-(fluoroalkoxyphosphazenes) have been successful. Derivatization of /Cl2PN/n polymer with alkoxides gave functionally reactive terpolymers. These terpolymers could be crosslinked with polyisocyanates at room temperature. Attempts to control molecular weight have not been as successful. The effects of (Cl2PN)3 monomer purity, use of (Cl2PN)3,4 mixture, and early termination of the bulk polymerization of (Cl2PN)3 were studied briefly. Both low and high molecular weight polymers were obtained. Reaction of NH4Cl with PCl5 with subsequent heating to give chain extension gave either gels of oils with molecular weights of several thousand. The stabilization of poly-(fluoroalkoxyphosphazene) was investigated. The results generally were inconclusive, but acids were found to be deleterious while bases had little discernible effect. Improvements in stability by modification of end groups was inconclusive

    Development of thermally stable phosphonitrile elastomers for advanced aerospace structures

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    Both high and low molecular weight, curable poly(fluoroalkoxy phosphazene) terpolymers were prepared. These terpolymers resulted from reaction of (Cl2PNn) polymer with alkoxides derived from CF3CH2OH and C3F7CH2OH, and an alkoxide derived from CH3CH(OH)C2H4OH. The terpolymers were crosslinked with polyisocyanates at room temperature. High molecular weight materials were converted into isocyanate prepolymers which as films underwent moisture cures at room temperature. Prepolymer solutions were stable for several days, and showed good adhesion. Also the effects of polymerization of (Cl2PN)3 were studied. Purified octachlorophosphazene, thiocyanate salts, or hydrogen chloride were employed in attempts to decrease molecular weight. Hydrogen chloride was found to be a good agent for preparation of low molecular weight poly(dichloro phosphazene)

    MODELING ALTERNATIVE POLICIES FOR GHG MITIGATION FROM FORESTRY AND AGRICULTURE

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    A key consideration for development of energy and climate policy affecting the forestry and agricultural sectors is that the selection of specific mechanisms implemented to achieve bioenergy production and/or greenhouse gas (GHG) mitigation targets may have substantial effects on landowner incentives to adopt alternative practices. For instance, the prices of allowances and offsets are expected to diverge under some policies being considered where there is a binding cap on the quantity of offsets from the agricultural and forest sectors. In addition, provisions that limit or exclude specific practices from receiving carbon payments will affect the quantity and cost of GHG mitigation opportunities available. In this study, the recently updated Forest and Agriculture Sector Optimization Model with GHGs (FASOMGHG) was used to estimate GHG mitigation potential for private land in the contiguous U.S. under a variety of GHG price policies. Model scenarios suggest that U.S. forestry and agriculture could provide mitigation of 200 – 1000 megatons carbon dioxide equivalent per year (Mt CO2e/year) at carbon prices of 15to15 to 50/tCO2e. Binding limits on offsets have increasingly large effects on both the total magnitude and distribution of GHG mitigation across options over time. In addition, discounting or excluding payments for forest sinks can reduce annualized land-based mitigation potential 37-90 percent relative to the full eligibility scenario whereas discounting or excluding agricultural practices reduces mitigation potential by less than 10 percent.Climate policy, energy policy, FASOMGHG, GHG mitigation, Agricultural and Food Policy, Environmental Economics and Policy, Resource /Energy Economics and Policy, C61, Q42, Q54,

    Reproduction in the Hispid Cotton Rat, \u3ci\u3eSigmodon-hispidus\u3c/i\u3e Say and Ord (Rodentia: Muridae), in Southeastern Virginia

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    The hispid cotton rat, Sigmodon hispidus Say and Ord, a species of the southwestern United States that has been moving northward and eastward in this century, was first observed in Virginia in 1940. In this study of the cotton rat in southeastern Virginia, most males were reproductively competent from February through November, embryos were recorded from March through October, and litter sizes were comparable to those from other locations except Kansas. Also unlike the cotton rat in Kansas, animals grew at substantial rates during the winter in Virginia. The hispid cotton rat seems to have adjusted its breeding season in Virginia by the cessation of breeding early in autumn, which permits the last young of the season to attain nearly adult size before winter arrives. Both young and adults are able to maintain and even increase their autumnal body mass throughout the winter. Timing and length of the breeding season and the patterns of body growth suggest that the hispid cotton rat is well adapted to winter, and hence to persistence of the species, in southeastern Virginia

    The limits of process: On (re)reading Henri Bergson

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    This article offers a reading of the work of Henri Bergson as it pertains to organizations through the lens of ideas drawn from critical realism. It suggests an alternative to interpretations based on a stark division between process and realist perspectives. Much of the existing literature presents a rather partial view of Bergson’s work. A review suggests some interesting parallels with themes in critical realism, notably the emergence of mind. Critical realism has a focus on process at its heart, but is also concerned with how the products of such processes become stabilized and form the conditions for action. This suggests that attention might usefully be paid to the relationship between organizational action and the sedimented practices grouped under the heading of ‘routines’. More attention to Bergson’s account of the relationship between instinct, intuition and intelligence provides a link to the social character of thought, something which can be mapped on to Archer’s work on reflexivity and the ‘internal conversation’. This suggests that our analyses need to pay attention to both memory and history, to building and dwelling, rather than the one-sided focus found in some process theory accounts

    Collective multipole-like signatures of entanglement in symmetric N-qubit systems

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    A cogent theory of collective multipole-like quantum correlations in symmetric multiqubit states is presented by employing SO(3) irreducible spherical tensor representation. An arbitrary bipartite division of this system leads to a family of inequalities to detect entanglement involving averages of these tensors expressed in terms of the total system angular momentum operator. Implications of this theory to the quantum nature of multipole-like correlations of all orders in the Dicke states are deduced. A selected set of examples illustrate these collective tests. Such tests detect entanglement in macroscopic atomic ensembles, where individual atoms are not accessible.Comment: REVTEX, 4 pages with 1 figure; To appear in Phys. Rev.

    Seeing the smart city on Twitter: Colour and the affective territories of becoming smart

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    This paper pays attention to the immense and febrile field of digital image files which picture the smart city as they circulate on the social media platform Twitter. The paper considers tweeted images as an affective field in which flow and colour are especially generative. This luminescent field is territorialised into different, emergent forms of becoming ‘smart’. The paper identifies these territorialisations in two ways: firstly, by using the data visualisation software ImagePlot to create a visualisation of 9030 tweeted images related to smart cities; and secondly, by responding to the affective pushes of the image files thus visualised. It identifies two colours and three ways of affectively becoming smart: participating in smart, learning about smart, and anticipating smart, which are enacted with different distributions of mostly orange and blue images. The paper thus argues that debates about the power relations embedded in the smart city should consider the particular affective enactment of being smart that happens via social media. More generally, the paper concludes that geographers must pay more attention to the diverse and productive vitalities of social media platforms in urban life and that this will require experiment with methods that are responsive to specific digital qualities

    Independent sexual violence advisers (ISVAs) in England, Wales and Northern Ireland: a study of impacts, effects, coping mechanisms and effective support systems for people working as ISVAs and ISVA Managers

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    This study is the first of its kind in England, Wales and Northern Ireland and was carried out to gather information about the impact of working as Independent Sexual Violence Advisers (ISVAs) or ISVA Managers. The ISVA role is relatively new, and as such, little is known about this difficult and emotionally charged work. Although some literature looks at the impact of working in the sexual violence field, there is little from England, Wales or Northern Ireland, and even less focused on the direct, ongoing, face-to-face work ISVAs do. This report focuses on the impacts, effects, coping mechanisms and effective support systems for people working as ISVAs and ISVA Managers in supporting victim-survivors of sexual violence across England, Wales and Northern Ireland. Since its introduction in 2005, the ISVA role has been invaluable in providing continuous support to victim-survivors of sexual violence and working to meet their emotional and practical needs during the criminal justice process. As conviction rates are at an all-time low, ISVAs can also provide support to people who may otherwise feel let down by the Criminal Justice System. ISVAs can also support people who do not want to report the crime to the police – helping people at, potentially, the lowest point of their life. This survey focused on providing an overview of the ISVA role (e.g. context they work in, caseloads, supervision and support available) and determining which factors predict the likelihood of experiencing negative and positive impacts as a result of the work they do

    Teleological Essentialism

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    Placeholder essentialism is the view that there is a causal essence that holds category members together, though we may not know what the essence is. Sometimes the placeholder can be filled in by scientific essences, such as when we acquire scientific knowledge that the atomic weight of gold is 79. We challenge the view that placeholders are elaborated by scientific essences. On our view, if placeholders are elaborated, they are elaborated Aristotelian essences, a telos. Utilizing the same kinds of experiments used by traditional essentialists—involving superficial change (study 1), transformation of insides (study 2), acquired traits (study 3) and inferences about offspring (study 4)—we find support for the view that essences are elaborated by a telos. And we find evidence (study 5) that teleological essences may generate category judgments
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