6,835 research outputs found

    Exploiting soliton decay and phase fluctuations in atom chip interferometry of Bose-Einstein condensates

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    We show that the decay of a soliton into vortices provides a mechanism for measuring the initial phase difference between two merging Bose-Einstein condensates. At very low temperatures, the mechanism is resonant, operating only when the clouds start in anti-phase. But at higher temperatures, phase fluctuations trigger vortex production over a wide range of initial relative phase, as observed in recent experiments at MIT. Choosing the merge time to maximize the number of vortices created makes the interferometer highly sensitive to spatially varying phase patterns and hence atomic movement.Comment: 5 pages, 5 figure

    Implications of non-feasible transformations among icosahedral hh orbitals

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    The symmetric group S6S_6 that permutes the six five-fold axes of an icosahedron is introduced to go beyond the simple rotations that constitute the icosahedral group II. Owing to the correspondence h↔dh\leftrightarrow d, the calculation of the Coulomb energies for the icosahedral configurations hNh^N based on the sequence O(5)⊃S6⊃S5⊃IO(5) \supset S_6 \supset S_5 \supset I can be brought to bear on Racah's classic theory for the atomic d shell based on SO(5)⊃SOL(3)⊃ISO(5) \supset SO_L(3) \supset I. Among the elements of S6S_6 is the kaleidoscope operator K{\cal K} that rotates the weight space of SO(5) by π/2\pi/2. Its use explains some puzzling degeneracies in d^3 involving the spectroscopic terms ^2P, ^2F, ^2G and ^2H.Comment: Tentatively scheduled to appear in Physical Preview Letters Apr 5, 99. Revtex, 1 ps figur

    Calibration of the EDGES High-Band Receiver to Observe the Global 21-cm Signature from the Epoch of Reionization

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    The EDGES High-Band experiment aims to detect the sky-average brightness temperature of the 2121-cm signal from the Epoch of Reionization (EoR) in the redshift range 14.8≳z≳6.514.8 \gtrsim z \gtrsim 6.5. To probe this redshifted signal, EDGES High-Band conducts single-antenna measurements in the frequency range 90−19090-190 MHz from the Murchison Radio-astronomy Observatory in Western Australia. In this paper, we describe the current strategy for calibration of the EDGES High-Band receiver and report calibration results for the instrument used in the 2015−20162015-2016 observational campaign. We propagate uncertainties in the receiver calibration measurements to the antenna temperature using a Monte Carlo approach. We define a performance objective of 11~mK residual RMS after modeling foreground subtraction from a fiducial temperature spectrum using a five-term polynomial. Most of the calibration uncertainties yield residuals of 11~mK or less at 95%95\% confidence. However, current uncertainties in the antenna and receiver reflection coefficients can lead to residuals of up to 2020 mK even in low-foreground sky regions. These dominant residuals could be reduced by 1) improving the accuracy in reflection measurements, especially their phase 2) improving the impedance match at the antenna-receiver interface, and 3) decreasing the changes with frequency of the antenna reflection phase.Comment: Updated to match version accepted by Ap

    Quality Assurance in Telehealth: Adherence to Evidence-Based Indicators.

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    Background: Value enhancing telehealth (TH) lacks a robust body of formal clinically focused quality assessment studies. Innovations such as telehealth must always demonstrate that it preserves or hopefully advances quality. Introduction: We sought to determine whether adherence to the evidence-based Choosing Wisely (CW) recommendations (antibiotic stewardship) for acute sinusitis differs for encounters through direct-to-consumer (DTC) telemedicine verses in-person care in an emergency department (ED) or an urgent care (UC) center. Materials and Methods: Study design was a retrospective review. Patients with a symptom complex consistent with acute sinusitis treated through DTC were matched with ED and UC patients, based upon time of visit. Charts were reviewed to determine patient characteristics, chief complaint, final diagnosis, presence or absence of criteria within the CW guidelines, and whether or not antibiotics were prescribed. The main outcome was adherence to the CW campaign recommendations. Results: A total of 570 visits were studied: 190 DTC, 190 ED, and 190 UC visits. The predominant chief complaints were upper respiratory infection (36%), sore throat (25%), and sinusitis (18%). Overall, there was a 67% (95% CI 62.3-71.7) adherence rate with the CW guidelines for sinusitis: DTC visits (71%), ED visits (68%), and UC visits (61%). There was a nonsignificant difference (p = 0.29) in adherence to CW guidelines based upon type of visit (DTC, UC, and ED). Discussion: The challenge is to demonstrate whether or not DTC TH compromises quality. Conclusion: In this study, DTC visits were associated with at least as good an adherence to the CW campaign recommendations as emergency medicine (EM) and UC in-person visits. © Daniel Halpren-Ruder et al

    An Occupational Therapy Approach to Education for Foster Parents

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    The focus of this project is to enhance current programming for foster parent pre-licensure education courses in San Diego, California. This capstone project focused on the preferred learning styles of foster parents and utilized adult learning theories to create suggestions to enhance the current pre-licensure class curriculum. Data collected during verbal interviews with foster parents helped guide the suggestions to enhance the current curriculum. Utilizing specific occupational therapy group strategies, occupational therapists can help enhance education for foster parents by increasing the saliency of the learning material. The increased saliency facilitates a deeper understanding of the material and increases the retention of knowledge amongst participants. The capstone project will explore how occupational therapists can help enhance the current pre-licensure curriculum for foster parents to be more inclusive of different learning styles
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