4,154 research outputs found

    Quantum quenches in disordered systems: Approach to thermal equilibrium without a typical relaxation time

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    We study spectral properties and the dynamics after a quench of one-dimensional spinless fermions with short-range interactions and long-range random hopping. We show that a sufficiently fast decay of the hopping term promotes localization effects at finite temperature, which prevents thermalization even if the classical motion is chaotic. For slower decays, we find that thermalization does occur. However, within this model, the latter regime falls in an unexpected universality class, namely, observables exhibit a power-law (as opposed to an exponential) approach to their thermal expectation values.Comment: 5 pages, 5 figure

    How to match the optimal currently available inhaler device to an individual child with asthma or recurrent wheeze

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    This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in the credit line; if the material is not included under the Creative Commons license, users will need to obtain permission from the license holder to reproduce the material. To view a copy of this license, visit http://creativecommons.org/licenses/by-nc-sa/4.0/Peer reviewedPublisher PD

    SOCIAL JUSTICE WARRIORS: COACHING TEACHERS TO ENACT CULTURALLY RESPONSIVE PEDAGOGY

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    This project centered on culturally and linguistically responsive pedagogy (CLRP) with the intention of increasing opportunities for rigorous academic discourse in middle school humanities classrooms. In collaboration with a team of a co-practitioner-researchers composed of three teachers, an instructional coach, and an administrator, my goal was to examine how we could adapt culturally and linguistically responsive practices to increase academic rigor. The teachers believed culturally responsive teaching is social justice teaching, and they created opportunities to empower students by cultivating relationships with students and adapting curriculum content; however, as committed social justice educators, they did not consistently use pedagogical practices that represented high cognitive demand. Through three cycles of inquiry, their pedagogical approaches improved by (a) participating in a community of practice (CoP) that supported the conditions for adult learning and (b) engaging in a dynamic coaching model that utilized evidence-based classroom observation to guide conversations. As a result, teachers shifted their pedagogical practices toward higher cognitive demand. I present a framework for change in teacher practice that requires focused professional learning incubated in a community of practice (CoP) that is supported with coaching. As practice communities focused on improving the outcomes for vulnerable students and addressing the opportunity gap, we need evidence of how teachers who espouse social justice principles actually enact their principles pedagogically in the classrooms. The findings from this study provide valuable insights into how strong relationships with students and a belief in the power of student voice can lead teachers to higher expectations and cognitive rigor

    What faces reveal : a novel method to identify patients at risk of deterioration using facial expressions

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    Objectives: To identify facial expressions occurring in patients at risk of deterioration in hospital wards. Design: Prospective observational feasibility study. Setting: General ward patients in a London Community Hospital, United Kingdom. Patients: Thirty-four patients at risk of clinical deterioration. Interventions: A 5-minute video (25 frames/s; 7,500 images) was recorded, encrypted, and subsequently analyzed for action units by a trained facial action coding system psychologist blinded to outcome. Measurements and Main Results: Action units of the upper face, head position, eyes position, lips and jaw position, and lower face were analyzed in conjunction with clinical measures collected within the National Early Warning Score. The most frequently detected action units were action unit 43 (73%) for upper face, action unit 51 (11.7%) for head position, action unit 62 (5.8%) for eyes position, action unit 25 (44.1%) for lips and jaw, and action unit 15 (67.6%) for lower face. The presence of certain combined face displays was increased in patients requiring admission to intensive care, namely, action units 43 + 15 + 25 (face display 1, p < 0.013), action units 43 + 15 + 51/52 (face display 2, p < 0.003), and action units 43 + 15 + 51 + 25 (face display 3, p < 0.002). Having face display 1, face display 2, and face display 3 increased the risk of being admitted to intensive care eight-fold, 18-fold, and as a sure event, respectively. A logistic regression model with face display 1, face display 2, face display 3, and National Early Warning Score as independent covariates described admission to intensive care with an average concordance statistic (C-index) of 0.71 (p = 0.009). Conclusions: Patterned facial expressions can be identified in deteriorating general ward patients. This tool may potentially augment risk prediction of current scoring systems

    Reheating constraints and consistency relations of the Starobinsky model and some of its generalizations

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    Building on the success of the Starobinsky model in describing the inflationary period of the universe, we investigate two simple generalizations of this model and their constraints imposed by the reheating epoch. The first generalization takes the form R2pR^{2p}, while the second is the α\alpha-Starobinsky model. We first focus on the case where p=1p=1 or equivalently, α=1\alpha=1, which corresponds to the original Starobinsky model. We derive exact consistency relations between observables and cosmological quantities, without neglecting any terms, and impose the reheating condition 0<ωre<0.250 < \omega_{re} < 0.25, where ωre\omega_{re} is the equation of state parameter at the end of reheating. This allows us to obtain new bounds for nsn_s and rr that satisfy this condition and apply them to other observables and cosmological quantities. We repeat this process for the cases where p1p \neq 1 and α1\alpha \neq 1 and find that these generalizations only result in minor modifications of the Starobinsky model, including the potential and the bounds on observables and cosmological quantities.Comment: 17 pages, 2 figure

    Proposal of a methodology for implementing a service-oriented architecture in distributed manufacturing systems

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    As envisioned by Intelligent Manufacturing Systems (IMS), Next Generation Manufacturing Systems (NGMS) will satisfy the needs of an increasingly fast-paced and demanding market by dynamically integrating systems from inside and outside the manufacturing firm itself into a so-called extended enterprise. However, organizing these systems to ensure the maximum flexibility and interoperability with those from other organizations is difficult. Additionally, a defect in the system would have a great impact: it would affect not only its owner, but also its partners. For these reasons, we argue that a service-oriented architecture (SOA) would be a good candidate. It should be designed following a methodology where services play a central role, instead of being an implementation detail. In order for the architecture to be reliable enough as a whole, the methodology will need to help find errors before they arise in a production environment. In this paper we propose using SOA-specific testing techniques, compare some of the existing methodologies and outline several extensions upon one of them to integrate testing techniques

    Variational Approach to Gaussian Approximate Coherent States: Quantum Mechanics and Minisuperspace Field Theory

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    This paper has a dual purpose. One aim is to study the evolution of coherent states in ordinary quantum mechanics. This is done by means of a Hamiltonian approach to the evolution of the parameters that define the state. The stability of the solutions is studied. The second aim is to apply these techniques to the study of the stability of minisuperspace solutions in field theory. For a λφ4\lambda \varphi^4 theory we show, both by means of perturbation theory and rigorously by means of theorems of the K.A.M. type, that the homogeneous minisuperspace sector is indeed stable for positive values of the parameters that define the field theory.Comment: 26 pages, Plain TeX, no figure

    Traversing the pyrochlore stability diagram; microwave-assisted synthesis and discovery of mixed B-site Ln2_2InSbO7_7 family

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    The lanthanide pyrochlore oxides Ln2_2B2_2O7_7 are one of the most intensely studied classes of materials within condensed matter physics, firmly centered as one of the pillars of frustrated magnetism. The extensive chemical diversity of the pyrochlores, coupled with their innate geometric frustration, enables realization of a wide array of exotic and complex magnetic ground states. Thus, the discovery of new pyrochlore compositions has been a persistent theme that continues to drive the field in exciting directions. The recent focus on the mixed B-site pyrochlores offers a unique route towards tuning both local coordination chemistry and sterics, while maintaining a nominally pristine magnetic sublattice. Here, we present a broad overview of the pyrochlore stability field, integrating recent synthetic efforts in mixed B-site systems with the historically established Ln2_2B2_2O7_7 families. In parallel, we present the discovery and synthesis of the entire Ln2_2InSbO7_7 family (Ln: La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu) located near the boundary of the pyrochlore stability field using a rapid, hybrid mechanicochemical/microwave-assisted synthesis technique. Magnetic characterization on the entire class of compounds draws striking parallels to the stannate analogs, suggesting that these compounds may host a breadth of exotic magnetic ground states

    Evaluation of cholinergic markers in Alzheimer's disease and in a model of cholinergic deficit

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    Cognitive deficits in neuropsychiatric disorders, such as Alzheimer's disease (AD), have been closely related to cholinergic deficits. We have compared different markers of cholinergic function to assess the best biomarker of cognitive deficits associated to cholinergic hypoactivity. In post-mortem frontal cortex from AD patients, acetylcholine (ACh) levels, cholinacetyltransferase (ChAT) and acetylcholinesterase (AChE) activity were all reduced compared to controls. Both ChAT and AChE activity showed a significant correlation with cognitive deficits. In the frontal cortex of rats with a selective cholinergic lesion, all cholinergic parameters measured (ACh levels, ChAT and AChE activities, "in vitro" and "in vivo" basal ACh release) were significantly reduced. AChE activity was associated to ChAT activity, and even more, to "in vivo" and "in vitro" basal ACh release. Quantification of AChE activity is performed by an easy and cheap method and therefore, these results suggest that determination of AChE activity may be used as an effective first step method to evaluate cholinergic deficits
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