1,238 research outputs found

    Understanding Teacher Leadership in Middle School Mathematics: A Collaborative Research Effort

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    We report findings from a collaborative research effort designed to examine how teachers act as leaders in their schools. We find that teachers educated by the Math in the Middle Institute act as key sources of advice for colleagues within their schools while drawing support from a network consisting of other teachers in the program and university-level advisors. In addition to reporting on our findings, we reflect on our research process, noting some of the practical challenges involved, as well as some of the benefits of collaboration

    Secure self-calibrating quantum random bit generator

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    Random bit generators (RBGs) are key components of a variety of information processing applications ranging from simulations to cryptography. In particular, cryptographic systems require "strong" RBGs that produce high-entropy bit sequences, but traditional software pseudo-RBGs have very low entropy content and therefore are relatively weak for cryptography. Hardware RBGs yield entropy from chaotic or quantum physical systems and therefore are expected to exhibit high entropy, but in current implementations their exact entropy content is unknown. Here we report a quantum random bit generator (QRBG) that harvests entropy by measuring single-photon and entangled two-photon polarization states. We introduce and implement a quantum tomographic method to measure a lower bound on the "min-entropy" of the system, and we employ this value to distill a truly random bit sequence. This approach is secure: even if an attacker takes control of the source of optical states, a secure random sequence can be distilled.Comment: 5 pages, 2 figure

    Abstract robust coarse spaces for systems of PDEs via generalized eigenproblems in the overlaps

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    Coarse spaces are instrumental in obtaining scalability for domain decomposition methods for partial differential equations (PDEs). However, it is known that most popular choices of coarse spaces perform rather weakly in the presence of heterogeneities in the PDE coefficients, especially for systems of PDEs. Here, we introduce in a variational setting a new coarse space that is robust even when there are such heterogeneities. We achieve this by solving local generalized eigenvalue problems in the overlaps of subdomains that isolate the terms responsible for slow convergence. We prove a general theoretical result that rigorously establishes the robustness of the new coarse space and give some numerical examples on two and three dimensional heterogeneous PDEs and systems of PDEs that confirm this property

    Einstein equations in the null quasi-spherical gauge

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    The structure of the full Einstein equations in a coordinate gauge based on expanding null hypersurfaces foliated by metric 2-spheres is explored. The simple form of the resulting equations has many applications -- in the present paper we describe the structure of timelike boundary conditions; the matching problem across null hypersurfaces; and the propagation of gravitational shocks.Comment: 12 pages, LaTeX (revtex, amssymb), revision 18 pages, contains expanded discussion and explanations, updated references, to appear in CQ

    Strong Interactions of Single Atoms and Photons near a Dielectric Boundary

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    Modern research in optical physics has achieved quantum control of strong interactions between a single atom and one photon within the setting of cavity quantum electrodynamics (cQED). However, to move beyond current proof-of-principle experiments involving one or two conventional optical cavities to more complex scalable systems that employ N >> 1 microscopic resonators requires the localization of individual atoms on distance scales < 100 nm from a resonator's surface. In this regime an atom can be strongly coupled to a single intracavity photon while at the same time experiencing significant radiative interactions with the dielectric boundaries of the resonator. Here, we report an initial step into this new regime of cQED by way of real-time detection and high-bandwidth feedback to select and monitor single Cesium atoms localized ~100 nm from the surface of a micro-toroidal optical resonator. We employ strong radiative interactions of atom and cavity field to probe atomic motion through the evanescent field of the resonator. Direct temporal and spectral measurements reveal both the significant role of Casimir-Polder attraction and the manifestly quantum nature of the atom-cavity dynamics. Our work sets the stage for trapping atoms near micro- and nano-scopic optical resonators for applications in quantum information science, including the creation of scalable quantum networks composed of many atom-cavity systems that coherently interact via coherent exchanges of single photons.Comment: 8 pages, 5 figures, Supplemental Information included as ancillary fil

    Thromboembolic risk with IVIg: Incidence and risk factors in inflammatory neuropathy patients

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    Our objective was to evaluate whether IV immunoglobulin (IVIg) increases the risk of thromboembolic events in neurology outpatients with inflammatory neuropathies, as there is conflicting evidence supporting this hypothesis, mainly from non-neurologic cohorts. We investigated this question over 30 months in our cohort of patients with inflammatory neuropathies receiving regular IVIg anOur objective was to evaluate whether IV immunoglobulin (IVIg) increases the risk of thromboembolic events in neurology outpatients with inflammatory neuropathies, as there is conflicting evidence supporting this hypothesis, mainly from non-neurologic cohorts. We investigated this question over 30 months in our cohort of patients with inflammatory neuropathies receiving regular IVIg and found a greater incidence of arterial and venous thromboembolic events than population-based rates determined by hospital admissions data. Vascular risk factors were more common in the event group but there were no IVIg administration factors that contributed to the risk. This study suggests that IVIg may have a small but contributory role in determining thromboembolic risk in the inflammatory neuropathy cohort and more evidence is required before it is clear whether the current primary prevention guidelines are appropriate in this group of patients.d found a greater incidence of arterial and venous thromboembolic events than population-based rates determined by hospital admissions data. Vascular risk factors were more common in the event group but there were no IVIg administration factors that contributed to the risk. This study suggests that IVIg may have a small but contributory role in determining thromboembolic risk in the inflammatory neuropathy cohort and more evidence is required before it is clear whether the current primary prevention guidelines are appropriate in this group of patients

    Shared leadership and group identification in healthcare: : The leadership beliefs of clinicians working in interprofessional teams

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    This is an Accepted Manuscript of an article published by Taylor & Francis in Journal of Interprofessional Care on 28 February 2017, available online: http://www.tandfonline.com/doi/full/10.1080/13561820.2017.1280005.Despite the proposed benefits of applying shared and distributed leadership models in healthcare, few studies have explored the leadership beliefs of clinicians and ascertained whether differences exist between professions. The current paper aims to address these gaps and additionally, examine whether clinicians’ leadership beliefs are associated with the strength of their professional and team identifications. An online survey was responded to by 229 healthcare workers from community interprofessional teams in mental health settings across the East of England. No differences emerged between professional groups in their leadership beliefs; all professions reported a high level of agreement with shared leadership. A positive association emerged between professional identification and shared leadership i.e. participants who expressed the strongest level of profession identification also reported the greatest agreement with shared leadership. The same association was demonstrated for team identification and shared leadership. The findings highlight the important link between group identification and leadership beliefs, suggesting that strategies that promote strong professional and team identifications in interprofessional teams are likely to be conducive to clinicians supporting principles of shared leadership. Future research is needed to strengthen this link and examine the leadership practices of healthcare workers.Peer reviewe

    The influence of distributed leadership on teachers' organizational commitment: a multilevel approach

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    In the present study the effects of a cooperative leadership team, distributed leadership, participative decision-making, and context variables on teachers' organizational commitment are investigated. Multilevel analyses on data from 1522 teachers indicated that 9% of the variance in teachers' organizational commitment is attributable to differences between schools. The analyses revealed that especially the presence of a cooperative leadership team and the amount of leadership support played a significantly positive key role in predicting teachers' organizational commitment. Also, participative decision-making and distribution of the supportive leadership function had a significant positive impact on teachers' organizational commitment. In contrast, distribution of the supervisory leadership function and teachers' job experience had a significant negative impact

    Delayed ethylene glycol poisoning presenting with abdominal pain and multiple cranial and peripheral neuropathies: a case report

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    <p>Abstract</p> <p>Introduction</p> <p>Ethylene glycol poisoning may pose diagnostic difficulties if the history of ingestion is not volunteered, or if the presentation is delayed. This is because the biochemical features of high anion-gap metabolic acidosis and an osmolar gap resolve within 24 to 72 hours as the ethylene glycol is metabolized to toxic metabolites. This case illustrates the less well-known clinical features of delayed ethylene glycol poisoning, including multiple cranial and peripheral neuropathies, and the clinical findings which may point towards this diagnosis in the absence of a history of ingestion.</p> <p>Case presentation</p> <p>A 53-year-old Afro-Caribbean man presented with vomiting, abdominal pain and oliguria, and was found to have acute renal failure requiring emergency hemofiltration, and raised inflammatory markers. Computed tomography imaging of the abdomen revealed the appearance of bilateral pyelonephritis, however he failed to improve with broad-spectrum antibiotics, and subsequently developed multiple cranial neuropathies and increasing obtundation, necessitating intubation and ventilation. Computed tomography of the brain showed no focal lesions, and a lumbar puncture revealed a raised cerebrospinal fluid opening pressure and cyto-albuminological dissociation. Nerve conduction studies revealed a sensorimotor radiculoneuropathy mimicking a Guillain-Barre type lesion with an atypical distribution. It was only about two weeks after presentation that the history of ethylene glycol ingestion one week before presentation was confirmed. He had a slow recovery on the intensive care unit, requiring renal replacement therapy for eight weeks, and complicated by acute respiratory distress syndrome, neuropathic pain and a slow neurological recovery requiring prolonged rehabilitation.</p> <p>Conclusions</p> <p>Although neuropathy as a result of ethylene glycol poisoning has been described in a few case reports, all of these were in the context of a known history of ingestion. As the diagnosis may well be obscured if the history of ingestion is not elucidated, it is important to be aware of this possibility especially if presentation is delayed.</p
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