3,818 research outputs found
The reduction of metaphysics and the play of violence in the poetry of Wallace Stevens
No full textPhDThe thesis demonstrates how Wallace Stevens' poetry utilises pre-Socratic philosophy in overcoming post-Kantian dislocation from the 'thing-in-itself'. I initially consider Stevens’ poetry in terms of Hans-Georg Gadamer's ontological conception of the 'play' of art, an interactive existence overlooked by Kant. Through the ‘play’ of Stevens’ poems the reading audience are implicated in their reduction to being. The origin of this conception leads Gadamer back to Parmenides who Stevens had read. I argue that Stevens’ poetry ‘plays’ its audience into an ontological ground in an effort to show that his ‘reduction of metaphysics’ is not dry philosophical imposition, but is enacted by our encounter with the poems themselves. Through an analysis of how the language and form of Stevens’ poems attempt to reduce mind and world to concepts that parallel Parmenides’ poetic sense of being, and Heraclitus’ notion of becoming, the thesis uncovers the ground in which Stevens attempts a reconnection with the ‘thing-in-itself’. It is through the experience of reconnecting to an ontological centre, which his poetry presents as the human project, that Stevens’ poetry also presents itself as a means of replacing religion.From here we turn to Emmanuel Levinas and Jacques Derrida for an exposition of how such a reduction reduces the ‘Other’ to ‘otherness’ and their worry that this reduction legitimates violence within the thought of Martin Heidegger and Parmenides. From this I make a case for how such reductions are connected to what I refer to as 'the play of violence' in Stevens' poetry, and to refer this violence back to the mythology Stevens' poetry shares with certain pre-Socratics and with Greek tragedy. This shows how such mythic rhythms are apparent within the work of Friedrich Nietzsche, Heidegger and Gadamer, and how these rhythms release a poetic understanding of the violence of a ‘reduction of metaphysics’
A Transfer Report on the Development of a Framework to Evaluate Search Interfaces for their Support of Different User Types and Search Tactics
No full textAs the understanding of search systems, user needs and seeking strategies is developing, the design of search user interfaces is evolving to support more complicated and exploratory forms of search. With the design of new search features that enable these richer modes of exploration, comes the need to better understand the support they provide. In this report a new evaluation framework is presented that analyses search features for how they a) contribute to an overall interface, b) allow users to carry out different search tactics, and c) support different types of users and their needs. The novel contributions of the framework improve on some of the limitations of typical user studies, and allow search systems to be systematically analysed in much more detail and in much less time. The presented evaluation framework is then validated in three ways. First the validity of the models used as the building blocks of the framework are investigated through related work. Second the method of integrating these building-block models is validated and strengthened by consensus of expert opinion. Third, the overall approach is validated by comparing its analyses to the results of previously carried out user studies. The validation process has shown both the value of the framework and identified areas of future work that should be addressed for the framework to be completed. This report concludes with the set of contributions that the framework makes, and why the remaining work will be challenging, but critical to the final design
Synthesis and oxidation behaviour of Ta-Al-C MAX phases
No full textMAX-phase materials, a class of ternary carbides and nitrides that combine favorable properties of metals (conductivity and toughness) and ceramics (high temperature strength) have been shown to autonomously heal micro-cracks by high temperature oxidation. The investigation of Ta and Al containing MAX phases (Ta2AlC & Ta4AlC3) could render self-healing materials at lower temperatures. Mixed (Ta2AlC and Ta4AlC3) and pure dense bulk Ta2AlC MAX phase was synthesized by spark plasma sintering (SPS) of elemental powders. The oxidation reactions of Ta-Al-C MAX phase powders were studied with differential thermal analysis (DTA). The oxidation kinetics of dense bulk Ta-Al-C MAX phase was studied by thermal gravimetric analysis (TGA). The microstructure and composition of the MAX phase materials and its oxides was characterized by X-ray diffractometry (XRD), scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS), X-ray microanalysis with electron probe microanalysis (EPMA), and X-ray photoelectron spectroscopy (XPS). Linear oxidation kinetics, inward oxide growth and formation of mainly porous Ta-oxides were observed for isothermal oxidation of dense bulk Ta2AlC and mixed MAX phase. Based on the results obtained in this work, the oxides scales formed in the 600 – 800 °C temperature range are believed to consist of various metastable and/or amorphous oxides. Full oxidation of the MAX phase above 900 °C results in the formation of Ta2O5 and ternary TaAlO4. It was found that TaAl-C MAX phases cannot self-heal microcracks by formation of a protective oxide scale at elevated temperatures.Mechanical, Maritime and Materials EngineeringMaterial Science and Engineerin
The subzero microbiome: Microbial activity in frozen and thawing soils
No full textMost of the Earth's biosphere is characterized by low temperatures (<5 °C) and cold-adapted microorganisms are widespread. These psychrophiles have evolved a complex range of adaptations of all cellular constituents to counteract the potentially deleterious effects of low kinetic energy environments and the freezing of water. Microbial life continues into the subzero temperature range, and this activity contributes to carbon and nitrogen flux in and out of ecosystems, ultimately affecting global processes. Microbial responses to climate warming and in particular, thawing of frozen soils are not yet well understood although the threat of microbial contribution to positive feedback of carbon flux is substantial. To date, several studies have examined microbial community dynamics in frozen soils and permafrost due to changing environmental conditions, and some have undertaken the complicated task of characterizing microbial functional groups and how their activity changes with changing conditions, either in situ or by isolating and characterizing macromolecules. With increasing temperature and wetter conditions microbial activity of key microbes and subsequent efflux of greenhouse gases also increase. In this review, we aim to provide an overview of microbial activity in seasonally frozen soils and permafrost. With a more detailed understanding of the microbiological activities in these vulnerable soil ecosystems, we can begin to predict and model future expectations for carbon release and climate change.Peer reviewe
Measurement of the ratio of prompt χ c to J / ψ production in pp collisions at √s = 7 TeV
No full textThe prompt production of charmonium χ c and J / ψ states is studied in proton-proton collisions at a centre-of-mass energy of √s = 7 TeV at the Large Hadron Collider. The χ c and J / ψ mesons are identified through their decays χ c → J / ψ γ and J / ψ → μ + μ - using 36 pb - 1 of data collected by the LHCb detector in 2010. The ratio of the prompt production cross-sections for χ c and J / ψ, σ (χ c → J / ψ γ) / σ (J / ψ), is determined as a function of the J / ψ transverse momentum in the range 2 < p T J / ψ < 15 GeV / c. The results are in excellent agreement with next-to-leading order non-relativistic expectations and show a significant discrepancy compared with the colour singlet model prediction at leading order, especially in the low p T J / ψ region
L'immagine opaca. Il cinema di Max Ophuls
No full textChe cinema è quello di Max Ophuls? In che modo si inserisce nella storia del linguaggio cinematografico? Si tratta di un autore “classico”? Ma che cosa vuol dire “cinema narrativo classico”? E ancora: in che modo ha senso, oggi, studiare il cinema di un “autore”? In quale accezione leggiamo questo termine e in che rapporto sta con i macrosistemi (i generi, i contesti produttivi, la storia della tecnologia...) che sono stati l’oggetto, negli ultimi anni, della riflessione storiografica sul cinema? Il libro si propone di rispondere a tali questioni rileggendo l’opera di Max Ophuls (1902-1957) attraverso un’analisi stilistica fondata sul concetto di classicità ibrida e sulla reinterpretazione dell’idea di stile, visto come confronto incessante e forse irrisolvibile tra codice e scarto, tra norma e trasgressione.What kind of cinema is Max Ophuls's? In which way it enters the story of cinematic language? Is he a "classic" author? But what does it mean "classic narrative cinema"? Plus: does it make sense, today, to study the film of an "author"? What do we mean by this term and what kind of relation does it have with the macro systems (genres, productive contexts, history of technology...) that have been, in the recent years, the main focus of the historiographical reflection on film? The book aims at answering those questions through a re-reading of the work of Max Ophuls (1902-1957), with a stylistical analysis founded on the idea of hybrid classicism as well as on the reinterpretation of the idea of style, seen as a continuous -and maybe unsolvable - confrontation between code and deviation, rule and transgression
Arctic tundra soil bacterial communities active at subzero temperatures detected by stable isotope probing
No full textArctic soils store vast amounts of carbon and are subject to intense climate change. While effects of thaw on the composition and activities of Arctic tundra microorganisms has been examined extensively, little is known about the consequences of temperature fluctuations within the subzero range in seasonally frozen or permafrost soils. This study identified tundra soil bacteria active at subzero temperatures using stable isotope probing (SIP). Soils from Kilpisjärvi, Finland were amended with 13C-cellobiose and incubated at 0, -4, and -16°C for up to 40 weeks. 16S rRNA gene sequence analysis of 13C-labelled DNA revealed distinct subzero-active bacterial taxa. The SIP experiments demonstrated that diverse bacteria, including members of Candidatus Saccharibacteria, Melioribacteraceae, Verrucomicrobiaceae, Burkholderiaceae, Acetobacteraceae, Armatimonadaceae, and Planctomycetaceae were capable of synthesizing 13C-DNA at subzero temperatures. Differences in subzero temperature optima were observed, for example with members of Oxalobacteraceae and Rhizobiaceae found to be more active at 0°C than at -4°C or -16°C, whereas Melioribacteriaceae were active at all subzero temperatures tested. Phylogeny of 13C-labelled 16S rRNA genes from the Melioribacteriaceae, Verrucomicrobiaceae, and Candidatus Saccharibacteria suggested that these taxa formed subzero-active clusters closely related to members from other cryo-environments. This study demonstrates that subzero temperatures impact active bacterial community composition and activity which may influence biogeochemical cycles.Peer reviewe
Climate Justice Behind the Veil of Aggregation: IAMs, Equity, and Pareto-Optimal Abatement Pathways
No full textHumanity faces the unprecedented global challenge of climate change. The sheer complexity and uncertainty of this problem renders mere intuitive reasoning insufficient. To aid global climate negotiations, Integrated Assessment Models (IAMs) are used to analyze the interplay between climate and the economy. More specifically, IAMs account for how greenhouse gas emissions affect climate change, how climate change affects economic production, and how economic production affects GHG emissions. We can use IAMs to project trends in emissions and gross domestic product, assess the costs and benefits of climate policies, and estimate the social carbon cost required to achieve stated emissions reduction targets. Although IAMs are central to informing decision-making to avoid catastrophic consequences, policy recommendations resulting from IAMs commonly prompt a very heterogeneous distribution of risks and benefits across the globe. During the recent 2021 United Nations Climate Change Conference (COP26), it became clear that equity is a central issue in the climate action debate. Emerging economies consider currently suggested abatement policies unjust in light of the historical CO2 generation of high-income countries and the strongly increasing need for energy in low-income countries. The term double inequality has been coined to describe the inverse relationship between the distributions of risks and responsibilities. In fact, the regions that are the least responsible for historical and mostly current CO2 emissions around the world, exhibit the highest degree of vulnerability to climate damages. In order to enable international cooperation and have a shot at meeting the Paris Agreement target, we require policies that promote more equitable mitigation pathways. Equity is therefore an eminently pressing topic, yet most IAM studies largely neglect it due to the implicit use of a utilitarian social welfare function that aggregates risks and benefits over space and time, thus losing sight of distributional consequences. In order to account for distributional justice, we transform the RICE model into a simulation model and embed it in a many-objective simulation-optimization setup such that we can find Pareto-optimal climate mitigation pathways for different problem formulations. Next to using four ethical premises (rooted in utilitarianism, sufficientarianism, egalitarianism, and prioritarianism), we also direct particular attention to the disaggregation of utility and disutility within each of these ethical premises. The reason for this disaggregation is based on the incommensurability of these two. Usually, IAMs maximize aggregate variables such as welfare. If we also consider the minimization of welfare loss, which is based on economic damages as one of the objectives, we can enable a potentially fairer distribution of not only consumption but economic damages. We argue that we can find climate justice behind the veil of aggregation. What we mean by this is that more equitable policy recommendations are obscured and lie hidden behind a bulwark of highly aggregated variables. If we look beyond this obstruction by the means of disaggregation, we are better equipped to find climate justice. In order to get to the bottom of this, we ask the following question: How are Pareto-optimal climate abatement pathways affected by the disaggregation of utility and disutility in alternative ethical problem formulations when using an integrated assessment model under deep uncertainty?To answer this question, we use a framework that is called multi-scenario multi-objective robust decision-making. For each of the eight problem formulations (4 ethical premises x 2 levels of aggregation), we use a multi-objective evolutionary algorithm to find Pareto-optimal policies. We reevaluate their performances under uncertainty by comparing their climate abatement pathways across the problem formulations. On a high-level, we can summarize our key findings as: - dominance of aggregation levels over ethical premises - correlation between low welfare and high welfare loss - general dominance of egalitarian aggregated Pareto-optimal policies - shared misery via egalitarian disaggregated Pareto-optimal policiesThe effect of disaggregating utility and disutility is stronger than originally expected. Using disaggregated problem formulations yields substantially different pathways even within the same ethical premise. These results are promising as we could transfer these insights to other more complex IAMs such as IMAGE and MESSAGE. Overall, this could be also good news for the equity debate. Using alternative ethical premises and disaggregating incommensurate objectives such as utility and disutility can offer alternative policy recommendations and resulting climate abatement pathways which could in turn enable more equity. What we likely need now, is a stronger dialogue between the modelers and policy analysts on the one side and the stakeholders and decision-makers on the other side. The latter ones should not just blindly trust in the magical outputs of a model but they need to be involved to decide what problem formulations we need to use as there is no correct way to frame a complex real-world problem. As unmitigated climate damages exhibit an independent impact on a region's well-being, we could render IAMs more useful for climate policy if we a) acknowledge that the classical notion of welfare is obsolete, b) use a multi-objective approach, and c) let the decision-makers decide how they want to trade-off the various objectives in post. In this manner, we could use IAMs to advance into the direction of enabling a transition of more climate justice.https://github.com/max-reddel/PyRICE_2022 Associated GitHub repositoryEngineering and Policy Analysi
Work of adhesion of interfaces between M<sub>2</sub>AlC (M = Ti, V, Cr) MAX phases and α-Al<sub>2</sub>O<sub>3</sub>
No full textA fast and generic scheme is proposed to calculate the work of adhesion between two different materials or the cohesive energy between two crystal planes in a material. These calculations make use of the regular solution theory. This theory is extended to describe chemical interactions between atoms at either side of an interface. The so-called regular solution parameter is estimated from thermodynamic values tabulated or solution enthalpies obtained from a macroscopic atom model (MAM). Complex surface definitions at either side of an interface, both in composition and position of atoms, can be dealt with. The proposed scheme has been used to calculate the work of adhesion between M2AlC (M = Ti, V, Cr) type MAX phases and α-Al2O3. Next, the cohesive energy of the MAX-phases and alumina were determined. The cohesion of the M2AlC type MAX-phase is the weakest bond present in the M2AlC- α-Al2O3 systems.Accepted Author Manuscript(OLD) MSE-
Self-healing of yttrium-doped CR2ALC MAX phase coatings deposited by hipims
No full textSelf-healing materials allow for a design concept based on damage management where damage that is inflicted during operation can be healed autonomously. It has been shown that the Mn+1AXn phases Ti3AlC2, Ti2AlC and Cr2AlC exhibit autonomous self-healing behaviour. Cracks are filled and hence healed by oxidation products of the M and A elements in the MAX phase at high operating temperatures. After crack healing the fracture strength is recovered to the level of the virgin material. Cr2AlC MAX phase was shown to exhibit excellent erosion resistance and high damage tolerance. The oxide scale forming in the temperature range between 900- 1200°C after different oxidation times was studied. The influence of the addition of Y on the rate of oxidation of Cr2AlC films and on their self-healing behaviour was investigated. The aim of the ongoing research project is to assess the potential of Cr2AlC MAX phase coatings as autonomous self-healing material by understanding the basic physical and chemical principles governing multiple crack closure to heal erosion damage
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