1,215 research outputs found

    Reconstruction of eolian bed forms and paleocurrents from cross-bedded strata at Victoria Crater, Meridiani Planum, Mars

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    Outcrop exposures imaged by the Opportunity rover at Victoria Crater, a 750 m diameter crater in Meridiani Planum, are used to delineate sedimentary structures and further develop a dune-interdune depositional model for the region. The stratigraphy at Victoria Crater, observed during Opportunity's partial traverse of its rim, includes the best examples of meter-scale eolian cross bedding observed on Mars to date. The Cape St. Mary promontory, located at the southern end of the rim traverse, is characterized by meter-scale sets of trough cross bedding, suggesting northward migrating sinuous-crested bed forms. Cape St. Vincent, which is located at the opposite end of the traverse, shows tabular-planar stratification indicative of climbing bed forms with meter- to decameter-scale dune heights migrating southward. Promontories located between Cape St. Mary and Cape St. Vincent contain superposed stratigraphic units with northward and southward dipping beds separated by outcrop-scale bounding surfaces. These bounding surfaces are interpreted to be either reactivation and/or superposition surfaces in a complex erg sea. Any depositional model used to explain the bedding must conform to reversing northward and southward paleomigration directions and include multiple scales of bed forms. In addition to stratified outcrop, a bright diagenetic band is observed to overprint bedding and to lie on an equipotential parallel to the preimpact surface. Meter-scale cross bedding at Victoria Crater is similar to terrestrial eolian deposits and is interpreted as a dry dune field, comparable to Jurassic age eolian deposits in the western United States

    Finite-time blowup for a complex Ginzburg-Landau equation

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    We prove that negative energy solutions of the complex Ginzburg-Landau equation e−iΞut=Δu+∣u∣αue^{-i\theta} u_t = \Delta u+ |u|^{\alpha} u blow up in finite time, where \alpha >0 and \pi /2<\theta <\pi /2. For a fixed initial value u(0)u(0), we obtain estimates of the blow-up time TmaxΞT_{max}^\theta as Ξ→±π/2\theta \to \pm \pi /2 . It turns out that TmaxΞT_{max}^\theta stays bounded (respectively, goes to infinity) as Ξ→±π/2\theta \to \pm \pi /2 in the case where the solution of the limiting nonlinear Schr\"odinger equation blows up in finite time (respectively, is global).Comment: 22 page

    The dilatometry of monodisperse silica dispersions

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    Thesis (B.S.) in Chemical Engineering -- University of Illinois at Urbana-Champaign, 1987.Bibliography: leaf 46.Microfiche of typescript. [Urbana, Ill.]: Photographic Services, University of Illinois, U of I Library, [1987]. 2 microfiches (66 frames): negative

    Caricature and Hyperbole in Preservice Teacher Professional Development

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    Professional development (PD) “for diversity” aims to prepare teachers to support students from varying backgrounds to succeed, often in underresourced contexts. Although many teachers invite such inquiry as part of learning to teach, others resist “diversity” inquiry as extra to teaching, saying they cannot “do it all.” In this article, we discuss how preservice teachers at times caricature the requests of PD for diversity, hearing the task as a call to undertake superhuman tasks and to be people other than who they are. We argue that these caricatures require direct acknowledgment by both preservice teachers and teacher educators working in diverse contexts

    Emotion Knowledge, Loneliness, Negative Social Experiences, and Internalizing Symptoms Among Low‐income Preschoolers

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    Children with poor emotion knowledge (EK) skills are at risk for externalizing problems; less is known about early internalizing behavior. We examined multiple facets of EK and social‐emotional experiences relevant for internalizing difficulties, including loneliness, victimization, and peer rejection, in Head Start preschoolers (N = 134; M = 60 months). Results based on multiple informants suggest that facets of EK are differentially related to negative social‐emotional experiences and internalizing behavior and that sex plays a moderating role. Behavioral EK was associated with self‐reported loneliness, victimization/rejection, and parent‐reported internalizing symptoms. Emotion recognition and expressive EK were related to self‐reported loneliness, and emotion situation knowledge was related to parent‐reported internalizing symptoms and negative peer nominations. Sex moderated many of these associations, suggesting that EK may operate differently for girls vs. boys in the preschool social context. Results are discussed with regard to the role of EK for social development and intervention implications.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/110878/1/sode12083.pd

    Biobehavioral Indices of Emotion Regulation Relate to School Attitudes, Motivation, and Behavior Problems in a Low-Income Preschool Sample

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    Effective emotion regulation may promote resilience and preschool classroom adjustment by supporting adaptive peer interactions and engagement in learning activities. We investigated how hypothalamus-pituitary-adrenal axis (HPA) regulation, cardiac reactivity, and classroom emotion displays related to adjustment among low-income preschoolers attending Head Start. A total of 62 four-year-olds completed a laboratory session including a baseline soothing video; emotion-eliciting slides/video clips, and recovery. Salivary cortisol, heart rate, and vagal tone were measured throughout. Independent coders used handheld computers to observe classroom emotion expression/regulation. Teachers rated child motivation, persistence/attention, learning attitudes, and internalizing/externalizing symptoms. Results reveal associations between biobehavioral markers of regulatory capacity and early school adjustment.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73847/1/annals.1376.043.pd

    Type of atrial fibrillation and clinical outcomes in patients with heart failure and reduced ejection fraction

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    Background: Atrial fibrillation (AF) is common in heart failure (HF), but the outcome by type of AF is largely unknown. Objectives: This study investigated outcomes related to type of AF (paroxysmal, persistent or permanent, or new onset) in 2 recent large trials in patients with HF with reduced ejection fraction. Methods: The study analyzed patients in the PARADIGM-HF (Prospective comparison of ARNI with ACEI to Determine Impact on Global Mortality and morbidity in Heart Failure) and ATMOSPHERE (Aliskiren Trial to Minimize Outcomes in Patients with Heart Failure) trials. Multivariable Cox regression models were used to estimate hazard ratios (HRs) for outcomes related to AF type. Results: Of 15,415 patients, 5,481 (35.6%) had a history of AF at randomization, and of these, 1,645 (30.0%) had paroxysmal AF. Compared with patients without AF, patients with paroxysmal AF at randomization had a higher risk of the primary composite endpoint of cardiovascular death or HF hospitalization (HR: 1.20; 95% confidence interval [CI]: 1.09 to 1.32; p &#60; 0.001), HF hospitalization (HR: 1.34; 95% CI: 1.19 to 1.51; &#60; 0.001), and stroke (HR: 1.34; 95% CI: 1.02 to 1.76; p = 0.037), whereas the corresponding risks in patients with persistent or permanent AF were not elevated. Neither type of AF was associated with higher mortality. New onset AF was associated with the greatest risk of adverse outcomes: primary endpoint (HR: 2.21; 95% CI: 1.80 to 2.71), HF hospitalization (HR: 2.11; 95% CI: 1.58 to 2.81), stroke (HR: 2.20; 95% CI: 1.25 to 3.88), and all-cause mortality (HR: 2.26; 95% CI: 1.86 to 2.74), all p values &#60; 0.001, compared with patients without AF. Anticoagulants were used less often in patients with paroxysmal (53%) and new onset (16%) AF than in patients with persistent or permanent AF (71%). Conclusions: Among HF patients with a history of AF, those with paroxysmal AF were at greater risk of HF hospitalization and stroke than were patients with persistent or permanent AF, underlining the importance of anticoagulant therapy. New onset AF was associated with increased risk of all outcomes. (Prospective comparison of ARNI with ACEI to Determine Impact on Global Mortality and Morbidity in Heart Failure [PARADIGM-HF]; NCT01035255) (Aliskiren Trial to Minimize Outcomes in Patients with Heart Failure [ATMOSPHERE]; NCT00853658

    The sensory feedback mechanisms enabling couples to walk synchronously: An initial investigation

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    The inattentive eye often will not notice it, but synchronization among human walking partners is quite common. In this first investigation of this phenomenon, we studied its frequency and the mechanisms that contribute to this form of "entrainment." Specifically, by modifying the available communication links between two walking partners, we isolated the feedback mechanisms that enable couples to synchronize their stepping pattern when they walk side-by-side. Although subjects were unaware of the research aims and were not specifically asked to walk in synchrony, we observed synchronized walking in almost 50% of the walking trials, among couples who do not usually walk together. The strongest in-phase synchrony occurred in the presence of tactile feedback (i.e., handholding), perhaps because of lower and upper extremity coupling driven in part by arm swing. Interestingly, however, even in the absence of visual or auditory communication, couples also frequently walked in synchrony while 180 degrees out-of-phase, likely using different feedback mechanisms. These findings may partially explain how patients with certain gait disorders and disturbed rhythm enhance their gait when they walk with a partner and suggest alternative interventions that might improve the stepping pattern. Further, this preliminary investigation highlights the relatively ubiquitous nature of an interesting phenomenon that has not previously been studied and suggests that further work is needed to better understand the mechanisms that entrain the gait of two walking partners and allows couples to walk in synchrony with minimal or no conscious effort
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