21,014 research outputs found

    Investigation of fast initialization of spacecraft bubble memory systems

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    Bubble domain technology offers significant improvement in reliability and functionality for spacecraft onboard memory applications. In considering potential memory systems organizations, minimization of power in high capacity bubble memory systems necessitates the activation of only the desired portions of the memory. In power strobing arbitrary memory segments, a capability of fast turn on is required. Bubble device architectures, which provide redundant loop coding in the bubble devices, limit the initialization speed. Alternate initialization techniques are investigated to overcome this design limitation. An initialization technique using a small amount of external storage is demonstrated

    Quantum Control of Qubits and Atomic Motion Using Ultrafast Laser Pulses

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    Pulsed lasers offer significant advantages over CW lasers in the coherent control of qubits. Here we review the theoretical and experimental aspects of controlling the internal and external states of individual trapped atoms with pulse trains. Two distinct regimes of laser intensity are identified. When the pulses are sufficiently weak that the Rabi frequency Ω\Omega is much smaller than the trap frequency \otrap, sideband transitions can be addressed and atom-atom entanglement can be accomplished in much the same way as with CW lasers. By contrast, if the pulses are very strong (\Omega \gg \otrap), impulsive spin-dependent kicks can be combined to create entangling gates which are much faster than a trap period. These fast entangling gates should work outside of the Lamb-Dicke regime and be insensitive to thermal atomic motion.Comment: 16 pages, 15 figure

    Neutrino-12C scattering in the ab initio shell model with a realistic three-body interaction

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    We investigate cross sections for neutrino-12C exclusive scattering and for muon capture on 12C using wave functions obtained in the ab initio no-core shell model. In our parameter-free calculations with basis spaces up to the 6 hbarOmega we show that realistic nucleon-nucleon interactions, like e.g. the CD-Bonn, under predict the experimental cross sections by more than a factor of two. By including a realistic three-body interaction, Tucson-Melbourne TM'(99), the cross sections are enhanced significantly and a much better agreement with experiment is achieved. At the same time,the TM'(99) interaction improves the calculated level ordering in 12C. The comparison between the CD-Bonn and the three-body calculations provides strong confirmation for the need to include a realistic three-body interaction to account for the spin-orbit strength in p-shell nuclei.Comment: 6 pages, 2 figure

    Puerperal seizures: not the usual suspects

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    We present a case of puerperal seizures and neonatal flaccidity due to abuse and abrupt withdrawal from zolpidem, following an elective Caesarean delivery at term.Keywords: zolpidem, puerperal seizures, withdrawa

    Prompt Beta Spectroscopy as a Diagnostic for Mix in Ignited NIF Capsules

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    The National Ignition Facility (NIF) technology is designed to drive deuterium-tritium (DT) internal confinement fusion (ICF) targets to ignition using indirect radiation from laser beam energy captured in a hohlraum. Hydrodynamical instabilities at interfaces in the ICF capsule leading to mix between the DT fue l and the ablator shell material are of fundamental physical interest and can affect the performance characteristics of the capsule. In this Letter we describe new radiochemical diagnostics for mix processes in ICF capsules with plastic or Be (0.9%Cu) ablator shells. Reactions of high-energy tritons with shell material produce high-energy ÎČ\beta-emitters. We show that mix between the DT fuel and the shell material enhances high-energy prompt beta emission from these reactions by more than an order of magnitude over that expected in the absence of mix

    Coherent Error Suppression in Multi-Qubit Entangling Gates

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    We demonstrate a simple pulse shaping technique designed to improve the fidelity of spin-dependent force operations commonly used to implement entangling gates in trapped-ion systems. This extension of the M{\o}lmer-S{\o}rensen gate can theoretically suppress the effects of certain frequency and timing errors to any desired order and is demonstrated through Walsh modulation of a two-qubit entangling gate on trapped atomic ions. The technique is applicable to any system of qubits coupled through collective harmonic oscillator modes

    Cutting Ties with Pro-Ana: A Narrative Inquiry Concerning the Experiences of Pro-Ana Disengagement from Six Former Site Users.

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    Websites advocating the benefits of eating disorders (“Pro-Ana”) tend to reinforce and maintain restrictive eating and purging behaviors. Yet remarkably, no study has explored individual accounts of disengagement from these sites and the associated meanings. Using narrative inquiry, this study sought to address this gap. From the interviews of six women, two overarching storylines emerged. The first closely tied disengagement to recovery with varying positions of personal agency claimed: this ranged from enforced and unwelcomed breaks that ignited change, to a personal choice that became viable through the development of alternative social and personal identities. A strong counternarrative to “disengagement as recovery” also emerged. Here, disengagement from Pro-Ana was storied alongside a need to retain an ED lifestyle. With “recovery” being just one reason for withdrawal from Pro-Ana sites, clinicians must remain curious about the meanings individuals ascribe to this act, without assuming it represents a step toward recovery.Peer reviewedFinal Accepted Versio

    Walmart Impact on the Finance and Insurance Industry

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    Purpose This paper investigates the effect of Walmart presence on professional service firms within the finance and insurance sector. This paper also discusses the finance and insurance industry’s place within the Walmart ripple effect—changed retail sector leads to changed professional support services resulting in altered levels of social capital within the community. Design/Methodology The study uses county-level data from the state of Nebraska to examine the relationship between cumulative Walmart exposure and the number of firms, number of employees, and payroll levels within the finance and insurance (F&I) sector. These same variables are also investigated within two specific F&I industries—insurance and banking. Findings The study documents a negative association between cumulative Walmart presence and the number of employees in the finance and insurance industry and a positive relationship between Walmart exposure and F&I payroll levels. The insurance industry results are consistent with the F&I sector result relating to payroll, but show a significant positive relationship between cumulative Walmart exposure and number of insurance agencies. Empirical results from the commercial banking industry are consistent with both the F&I sector and insurance industries with a positive relationship between Walmart presence over time and payroll levels. Originality/value This study contributes to the Walmart effect literature by considering the impact of Walmart presence beyond the retail sector. The paper investigates the effect of Walmart on the finance and insurance profession, a sector that 1) competes directly with Walmart Supercenters for money services, 2) provides support services for retail businesses impacted by Walmart services, and 3) potentially suffers from centralized benefits provided to employees by Walmart headquarters rather than local insurers. The paper concludes that the mixed impact on professional firms results in social capital that could be both strengthened and challenged by Walmart presence

    Health System Performance for the High-Need Patient: A Look at Access to Care and Patient Care Experiences

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    Achieving a high-performing health system will require improving outcomes and reducing costs for high-need, high-cost patients—those who use the most health care services and account for a disproportionately large share of health care spending. Goal: To compare the health care experiences of adults with high needs—those with three or more chronic diseases and a functional limitation in the ability to care for themselves or perform routine daily tasks—to all adults and to those with multiple chronic diseases but no functional limitations. Methods: Analysis of data from the 2009–2011 Medical Expenditure Panel Survey. Key findings: High-need adults were more likely to report having an unmet medical need and less likely to report having good patient–provider communication. High-need adults reported roughly similar ease of obtaining specialist referrals as other adults and greater likelihood of having a medical home. While adults with private health insurance reported the fewest unmet needs overall, privately insured highneed adults reported the greatest difficulties having their needs met. Conclusion: The health care system needs to work better for the highest-need, most-complex patients. This study's findings highlight the importance of tailoring interventions to address their need
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