4,157 research outputs found
Quantum quenches in disordered systems: Approach to thermal equilibrium without a typical relaxation time
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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SOCIAL JUSTICE WARRIORS: COACHING TEACHERS TO ENACT CULTURALLY RESPONSIVE PEDAGOGY
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
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Visual analytics of flight trajectories for uncovering decision making strategies
In air traffic management and control, movement data describing actual and planned flights are used for planning, monitoring and post-operation analysis purposes with the goal of increased efficient utilization of air space capacities (in terms of delay reduction or flight efficiency), without compromising the safety of passengers and cargo, nor timeliness of flights. From flight data, it is possible to extract valuable information concerning preferences and decision making of airlines (e.g. route choice) and air traffic managers and controllers (e.g. flight rerouting or optimizing flight times), features whose understanding is intended as a key driver for bringing operational performance benefits. In this paper, we propose a suite of visual analytics techniques for supporting assessment of flight data quality and data analysis workflows centred on revealing decision making preferences
What faces reveal : a novel method to identify patients at risk of deterioration using facial expressions
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
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 , while the second is the
-Starobinsky model. We first focus on the case where or
equivalently, , 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 , where is the equation of state parameter
at the end of reheating. This allows us to obtain new bounds for and
that satisfy this condition and apply them to other observables and
cosmological quantities. We repeat this process for the cases where
and 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
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
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 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 LnInSbO family
The lanthanide pyrochlore oxides LnBO 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 LnBO families. In
parallel, we present the discovery and synthesis of the entire LnInSbO
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
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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