1,651 research outputs found
Advance and Retreat of Cordilleran Ice Sheets in Washington, U.S.A.
Cordilleran Ice Sheet glaciations show characteristic patterns of advance and retreat, consisting of (1) advance out outwash, (2) glacial scouring, (3) deposition of till, (4) deposition of recessional outwash south of Seattle in the southern Puget Lowland, glaciomarine drift in the northern lowland, and eskers, kames, and small moraines on the Columbia Plateau. Radiocarbon dates show that the Puget and Juan de Fuca lobes advanced and retreated synchronously. The Puget lobe backwasted to Seattle by 13.4-14 ka yrs BP, where the thinning ice floated in seawater northward to Canada by 13 ka yrs BP depositing glaciomarine drift contemporaneously over 18,000 km2. Compelling evidence against the backwasting, calving, terminus model for the origin of the glaciomarine drift includes: 1) abundant 14C dates demonstrate simultaneous deposition of glaciomarine drift over the entire area; 2) stagnant-ice deposits closely related to glaciomarine drift are not consistent with an actively-calving, backwasting terminus; 3) irrefutable evidence for the nonmarine origin of Deming sand shows that Cordilleran ice was absent immediately prior to deposition of the overlying glaciomarine drift. The pattern of events in the northern Puget Lowland includes: 1) glacial loading under 1800 m of ice during the Vashon maximum; 2) rapid glacial thinning and floating of the ice deposited Kulshan glaciomarine drift 12-13 ka yrs BP; 3) emergence and deposition of fluvial Deming sand 11.5 ka yrs BP; 4) resubmer-gence and deposition of Bellingham glaciomarine drift up to -200 m, well beyond global eustatic sea level rise; 5) emergence 10.5-11.5 ka yrs BP and deposition of Sumas outwash on Bellingham glaciomarine drift; 6) Holocene eustatic sea level rise kept pace with isostatic rebound, thus, post-Sumas marine terraces are absent.Dans la CordillĂšre, les glaciations se sont produites selon des modes caractĂ©ristiques d'avancĂ©e et de recul : 1) dĂ©pĂŽts fluvioglaciaires d'avancĂ©e; 2) poli glaciaire; 3) till; 4) dĂ©pĂŽts fluvio-glaciaires de retrait au sud de Seattle, dans le sud des basses-terres de Puget, dĂ©pĂŽts glacio-marins dans les basses-terres du nord, et eskers, terrasses fluvioglaciaires et petites moraines sur le plateau de Columbia. La datation au radiocarbone indique que les lobes de Puget et de Juan de Fuca ont avancĂ© et reculĂ© synchroniquement. Parmi les preuves qui nous contraignent Ă rejeter l'hypothĂšse selon laquelle un front en fusion, qui vĂȘlait, serait Ă l'origine des dĂ©pĂŽts glacio-marins, citons : 1) les nombreuses datations au radiocarbone qui rĂ©vĂšlent la mise en place simultanĂ©e de dĂ©pĂŽts glacio-marins sur tout le territoire; 2) les dĂ©pĂŽts issus de la fusion de la glace stagnante, intimement associĂ©s aux dĂ©pĂŽts glacio-marins; 3) les preuves irrĂ©futables d'une origine autre que marine des sables de Deming qui rĂ©vĂšlent que la CordillĂšre Ă©tait libre de glace immĂ©diatement avant la mise en place des dĂ©pĂŽts glacio-marins. Dans le nord des basses-terres de Puget le dĂ©roulement des Ă©vĂ©nements comprend les Ă©tapes suivantes : 1) au cours du maximum de Vashon, charge glaciaire sous 1800 m de glace; 2) 12-13 ka BP, amincissement rapide du glacier et dĂ©rive de la glace contribuant Ă la mise en place des dĂ©pĂŽts glacio-marins de Kulshan; 3) vers 11 500 ans BP, emersion et dĂ©pĂŽt des sables de Deming d'origine fluviale; 4) nouvelle submersion et mise en place des dĂ©pĂŽts glacio-marins de Bellingham jusqu'Ă une hauteur d'environ 200 m, bien supĂ©rieure Ă l'Ă©lĂ©vation eustatique du niveau de la mer; 5) vers 10 500-11 500 ans BP, emersion et mise en place des dĂ©pĂŽts fluvio-glaciaires de Sumas sur les dĂ©pĂŽts glacio-marins de Bellingham; 6) Ă l'HolocĂšne, Ă©lĂ©vation eustatique du niveau de la mer au mĂȘme rythme que le relĂšvement isostatique.Die Vereisung der Kordilleren-Eisdecke zeigt charakteristische VorstoB- und RĂčckzugsmuster, bestehend aus (1) glazialem SchwemmvorstoB, (2) glazialem Scheuern, (3) Ablagerung der GrundmorĂ ne, (4) Ablagerung von RĂčckzugsschwemm-Material sĂčdlich von Seattle im sĂ»dlichen Puget-Lowland, glaziomarines Material im nĂŽrdlichen Tiefland und Esker, Kames und kleine MorĂ nen auf dem Columbia-Plateau. Radiokarbondaten zeigen, daf3 die Puget - und Juan de Fuca-Loben gleichzeitig vorstieBen und sich zurĂ»ckzogen. Gegen das rĂčcklĂ ufige, kalbende Terminus-Modell fur den Ursprung des glaziomarinen Materials sprechen die folgenden Tatsachen in zwingender Weise: 1) zahlreiche '"C-Daten beweisen die gleichzeitige Ablagerung von glaziomarinem Material Ăčber das gesamte Gebiet; 2) Ablagerungen von stagnierendem Eis, die in enger Verbindung zu glaziomarinem Material stehen, stimmen nicht mit einem aktiv kalbenden rĂčcklĂ ufigen Terminus Ăčberein; 3) unwiderlegbares Beweismaterial fur den nichtmarinen Ursprung des Sands von Deming zeigt, daB es kein Kordilleren-Eis gab unmittelbar vor der Ablagerung darĂčberliegen-den glaziomarinen Materials. Die Abfolge der Ereignisse im nĂŽrdlichen Puget Lowland bein-haltet: 1) glaziale Fracht unter 1800 m Eis wĂ hrend des Vashon Maximums; 2) schnelles glaziales AusdĂčnnen und treibendes Eis lagerte 12-13 ka Jahre v.u.Z. das glazioma-rine Material von Kulshan ab; 3) Auftauchen und Ablagerung von Deming-FluBsand -11.5ka Jahre v.u.Z.; 4) Wiederuntertauchen und Ablagerung von glaziomarinem Belligham-Material bis zu - 200 m, weit Ăčber die globale eustatische Meeresan-hebung hinaus; 5) Auftauchen - 10.5-11.5 ka Jahre v.u.Z. und Ablagerung von Sumas-Schwemm-Material auf dem glaziomarinen Bellingham-Material; 6) die eustatische Anhebung des Meeresspiegels im HolozĂ n hielt Schritt mit dem isostatischen Ruckprall
Assessing climate model software quality: a defect density analysis of three models
A climate model is an executable theory of the climate; the model encapsulates climatological theories in software so that they can be simulated and their implications investigated. Thus, in order to trust a climate model, one must trust that the software it is built from is built correctly. Our study explores the nature of software quality in the context of climate modelling. We performed an analysis of defect reports and defect fixes in several versions of leading global climate models by collecting defect data from bug tracking systems and version control repository comments. We found that the climate models all have very low defect densities compared to well-known, similarly sized open-source projects. We discuss the implications of our findings for the assessment of climate model software trustworthiness
âI changed and hid my old waysâ: how social rejection and social identities shape wellbeing among ex-prisoners
Being a member of a rejected group negatively affects wellâbeing but can also increase group identification, which can have positive effects on wellâbeing. However, this rejectionâidentification model has never been investigated among the highly stigmatized group of exâprisoners. Furthermore, the potential buffering role of multiple group memberships has never been investigated within the rejectionâidentification model. We conduct a novel investigation of a combined rejectionâidentification and social cure model of groupâbased rejection among exâprisoners. A survey of 199 exâprisoners found that experiencing groupâbased rejection was associated with poorer wellâbeing and increased exâprisoner identification. However, identification as an exâprisoner magnified, rather than buffered, the relationship between rejection and reduced wellâbeing. Furthermore, the negative relationship between rejection and wellâbeing was particularly pronounced among exâprisoners with a higher number of group memberships. Exâprisoners with a greater number of group memberships experienced greater levels of rejection, suggesting group memberships increase their exposure to rejection. We therefore provide evidence of a boundary condition for the social cure properties of groups. Among members of strongly rejected social groups, multiple group memberships can be a social curse rather than social cure
Improving refugee well-being with better language skills and more intergroup contact
The effects of intergroup contact on prejudice are well established. However, its effects on minority group well-being have been rarely studied. We hypothesised that contact with members of the majority culture will be related to better well-being, and that this is facilitated by majority language proficiency. We tested this hypothesis in a three-wave longitudinal study of refugees over two years (N = 180). Cross-lagged path modelling confirmed that intergroup contact at earlier time points was associated with increased well-being at later time points; the reverse associations (from earlier well-being to later contact) were not reliable. Self-rated earlier English language competence was positively associated with later intergroup contact (but not the reverse), suggesting that improving majority language proficiency might be the key to better well-being of refugees, with intergroup contact being the mediator between language and well-being
Validating Requirements for Fault Tolerant Systems Using Model Checking
Model checking is shown to be an effective tool in validating the behavior of a fault tolerant embedded spacecraft controller. The case study presented here shows that by judiciously abstracting away extraneous complexity, the state space of the model could be exhaustively searched allowing critical functional requirements to be validated down to the design level. Abstracting away detail not germane to the problem of interest leaves by definition a partial specification behind. The success of this procedure shows that it is feasible to effectively validate a partial specification with this technique. Three anomalies were found in the system one of which is an error in the detailed requirements, and the other two are missing/ambiguous requirements. Because the method allows validation of partial specifications, it also is an effective methodology towards maintaining fidelity between a co-evolving specification and an implementation
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Accessing the phenomenon of incompatibility in working studentsâ experience of university life
University students in paid employment have less time for studying, report more stress, and participate in fewer extracurricular activities than non-employed students. These negative outcomes that result from combining work and study can cause employed students to experience the domains of work, study, and social life as practically incompatible, but also to experience a sense of identity incompatibility. Therefore, we used insights from previous quantitative and qualitative data on employed students and previous work on identity incompatibility to generate two research questions (RQs): RQ1. What type(s) of incompatibility (practical, identity or other) do employed students experience? and RQ2. What strategies have they adopted to reduce the experienced incompatibility? In order to answer these questions, we performed a thematic analysis with a deductive approach on transcripts from 21 UK university students who we interviewed. The students reported two types of incompatibilities: practical incompatibility, which stems from the lack of time, lack of energy, and lack of social contact associated with combining work and study; and identity incompatibility, which emanates from status differences and differences between oneâs own and othersâ perception of oneself. In order to reduce or resolve these incompatibilities, the students also developed practical (e.g. taking paid leave) and cognitive (e.g. compartmentalising contexts) strategies. Finally, the students also noted how the experience of practical incompatibility can reaffirm their values of hard work and productivity and make them resilient learners
The mediating role of social connectedness and hope in the relationship between group membership continuity and mental health problems for vulnerable young people
Tackling educational inequalities with social psychology: identities, contexts, and interventions
Some groups of studentsâtypically those who have suffered because of historical inequality in societyâdisproportionately experience psychological barriers to educational success. These psychological barriersâfeelings of threat to their social identity and the sense that their identity is incompatible with educational successâmake substantial contributions to inequalities in educational outcomes between groups, even beyond economic, historical, and structural inequalities. A range of wise psychological interventions can help remove these barriers by targeting studentsâ subjective interpretation of their local educational context. In this review, we outline the Identities in Context model of educational inequalities, which proposes that interactions between studentsâ social identities and features of the local educational contextâexpectations about a group's academic performance, a group's representation in positions associated with academic success, and a group's orientation towards educationâcan trigger social identity threat and identity incompatibility in ways that vary considerably across contexts. We present an implementation process, based on the Identities in Context model, that academic researchers, policymakers, and practitioners can follow to help them choose and tailor wise interventions that are effective in reducing educational inequalities in their local context. Throughout the review, we make policy recommendations regarding how educational practices can be altered to help remove psychological barriers for underperforming groups of students and so reduce educational inequalities
The relationships between internal and external threat and right-wing attitudes: A three-wave longitudinal study
The interplay between threat and right-wing attitudes has received much research attention, but its longitudinal relationship has hardly been investigated. In this study, we investigated the longitudinal relationships between internal and external threat and right-wing attitudes using a cross-lagged design at three different time points in a large nationally representative sample (N = 800). We found evidence for bidirectional relationships. Higher levels of external threat were related to higher levels of Right-Wing Authoritarianism and to both the egalitarianism and dominance dimensions of Social Dominance Orientation at a later point in time. Conversely, higher levels of RWA were also related to increased perception of external threat later in time. Internal threat did not yield significant direct or indirect longitudinal relationships with right-wing attitudes. Theoretical and practical implications of these longitudinal effects are discussed
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