3,594 research outputs found

    C-MOS array design techniques: SUMC multiprocessor system study

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    The current capabilities of LSI techniques for speed and reliability, plus the possibilities of assembling large configurations of LSI logic and storage elements, have demanded the study of multiprocessors and multiprocessing techniques, problems, and potentialities. Evaluated are three previous systems studies for a space ultrareliable modular computer multiprocessing system, and a new multiprocessing system is proposed that is flexibly configured with up to four central processors, four 1/0 processors, and 16 main memory units, plus auxiliary memory and peripheral devices. This multiprocessor system features a multilevel interrupt, qualified S/360 compatibility for ground-based generation of programs, virtual memory management of a storage hierarchy through 1/0 processors, and multiport access to multiple and shared memory units

    New Consequences of Induced Transparency in a Double-Lambda scheme: Destructive Interference In Four-wave Mixing

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    We investigate a four-state system interacting with long and short laser pulses in a weak probe beam approximation. We show that when all lasers are tuned to the exact unperturbed resonances, part of the four-wave mixing (FWM) field is strongly absorbed. The part which is not absorbed has the exact intensity required to destructively interfere with the excitation pathway involved in producing the FWM state. We show that with this three-photon destructive interference, the conversion efficiency can still be as high as 25%. Contrary to common belief,our calculation shows that this process, where an ideal one-photon electromagnetically induced transparency is established, is not most suitable for high efficiency conversion. With appropriate phase-matching and propagation distance, and when the three-photon destructive interference does not occur, we show that the photon flux conversion efficiency is independent of probe intensity and can be close to 100%. In addition, we show clearly that the conversion efficiency is not determined by the maximum atomic coherence between two lower excited states, as commonly believed. It is the combination of phase-matching and constructive interference involving the two terms arising in producing the mixing wave that is the key element for the optimized FWM generation. Indeed, in this scheme no appreciable excited state is produced, so that the atomic coherence between states |0> and |2> is always very small.Comment: Submitted to Phys. Rev. A, 7 pages, 4 figure

    Efficient Raman Sideband Generation in a Coherent Atomic Medium

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    We demonstrate the efficient generation of Raman sidebands in a medium coherently prepared in a dark state by continuous-wave low-intensity laser radiation. Our experiment is performed in sodium vapor excited in Λ\Lambda configuration on the D1_{1} line by two laser fields of resonant frequencies ω1\omega_{1} and ω2\omega_{2}, and probed by a third field % \omega_{3}. First-order sidebands for frequencies ω1\omega_{1}, ω2\omega_{2} and up to the third-order sidebands for frequency ω3\omega_{3} are observed. The generation starts at a power as low as 10 microwatt for each input field. Dependencies of the intensities of both input and generated waves on the frequency difference (ω1ω2\omega_{1}-\omega_{2}), on the frequency ω3\omega_{3} and on the optical density are investigated.Comment: 7 pages, 6 figure

    Computer Games Are Serious Business and so is their Quality: Particularities of Software Testing in Game Development from the Perspective of Practitioners

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    Over the last several decades, computer games started to have a significant impact on society. However, although a computer game is a type of software, the process to conceptualize, produce and deliver a game could involve unusual features. In software testing, for instance, studies demonstrated the hesitance of professionals to use automated testing techniques with games, due to the constant changes in requirements and design, and pointed out the need for creating testing tools that take into account the flexibility required for the game development process. Goal. This study aims to improve the current body of knowledge regarding software testing in game development and point out the existing particularities observed in software testing considering the development of a computer game. Method. A mixed-method approach based on a case study and an opinion survey was applied to collect quantitative and qualitative data from software professionals regarding the particularities of software testing in game development. Results. We analyzed over 70 messages posted on three well-established network of question-and-answer communities related to software engineering, software testing and game development and received answers of 38 professionals discussing differences between testing a computer game and a general software, and identified important aspects to be observed by practitioners in the process of planning, performing and reporting tests in this context. Conclusion. Considering computer games, software testing must focus not only on the common aspects of a general software, but also, track and investigate issues that could be related to game balance, game physics and entertainment related-aspects to guarantee the quality of computer games and a successful testing process

    Enhanced four-wave mixing via elimination of inhomogeneous broadening by coherent driving of quantum transition with control fields

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    We show that atoms from wide velocity interval can be concurrently involved in Doppler-free two-photon resonant far from frequency degenerate four-wave mixing with the aid of auxiliary electromagnetic field. This gives rise to substantial enhancement of the output radiation generated in optically thick medium. Numerical illustrations addressed to typical experimental conditions are given.Comment: LaTeX2e, hyperref, 7 pages, 5 figures, to appear in PRA 1 august 200

    From teaching physics to teaching children : beginning teachers learning from pupils

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    This paper discusses the development of beginning physics teachers' pedagogical content knowledge (PCK) in the context of teaching basic electricity during a one-year Professional Graduate Diploma in Education course (PGDE) and beyond. This longitudinal study used repeated semi-structured interviews over a period of four-and-a-half years. The interview schedule followed a line of development through the secondary school electrical syllabus in Scotland. Fifteen student teachers were interviewed during the PGDE year. Six of them were followed up at the end of the Induction Year (their first year as a newly qualified teacher), and again two-and-a-half years later. Thematic analysis of the interviews showed that before the beginning teachers had taught any classes, their initial focus was on how to transform their own subject matter knowledge (SMK) about electricity into forms that were accessible to pupils. As the beginning teachers gained experience working with classes, they gave vivid descriptions of interacting with particular pupils when teaching electricity which showed the development of their pedagogical knowledge. This played a significant role in the teachers' change of focus from teaching physics to teaching children as they transformed their SMK into forms that were accessible to pupils and developed their general pedagogical knowledge

    The roles of dispositional coping style and social support in helping people with respiratory disease cope with a breathlessness crisis

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    © 2019 John Wiley & Sons Ltd Aim: To explore the role of coping moderators in self-management of breathlessness crises by people with advanced respiratory disease. Design: A secondary analysis of semi-structured interview data. Methods: Interviews with patients who had advanced respiratory disease, chronic breathlessness and at least one experience where they considered presenting to Emergency but self-managed instead (a “near miss”). Participants were recruited from New South Wales, Queensland, Victoria, South Australia or Tasmania. Eligible caregivers were those who contributed to Emergency-related decision-making. Interviews were coded inductively and then deductively against the coping moderators social support and dispositional coping style, defined by the Transactional Model of Stress and Coping. Results: Interviews were conducted between October 2015 - April 2016 with 20 patients and three caregivers. Social networks offered emotional and practical support but also had potential for conflict with patients' ‘hardy’ coping style. Patient hardiness (characterized by a sense of ‘commitment’ and ‘challenge’) promoted a proactive approach to self-management but made some patients less willing to accept support. Information-seeking tendencies varied between patients and were sometimes shared with caregivers. An optimistic coping style appeared to be less equivocally beneficial. Conclusion: This study shows that social support and coping style may influence how people self-manage through their breathlessness crises and identified ways coping moderators can facilitate or hinder effective self-management. Impact: This study confers insights into how social-support and coping style can be supported and optimized to facilitate breathlessness self-management. Acknowledging coping moderator interactions is beneficial for developing resources and strategies that recognise patient mastery

    Randomized Trial of a Pharmacist-Delivered Intervention for Improving Lipid-Lowering Medication Adherence among Patients with Coronary Heart Disease

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    A randomized trial of a pharmacist-delivered intervention (PI) versus usual care (UC) was conducted; 689 subjects with known coronary heart disease were recruited from cardiac catheterization laboratories. Participants in the PI condition received 5 pharmacist-delivered telephone counseling calls post-hospital discharge. At one year, 65% in the PI condition and 60% in the UC condition achieved an LDL-C level <100 mg/dL (P = .29); mean statin adherence was 0.88 in the PI, and 0.90 in the UC (P = .51). The highest percentage of those who reached the LDL-C goal were participants who used statins as opposed to those who did not use statins (67% versus 58%, P = .05). However, only 53% and 56% of the patients in the UC and PI conditions, respectively, were using statins. We conclude that a pharmacist-delivered intervention aimed only at improving patient adherence is unlikely to positively affect outcomes. Efforts must be oriented towards influencing physicians to increase statin prescription rates

    Individual leader to interdependent leadership: A case study in leadership development and tripartite evaluation

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    This article is available open access through the publisher’s website at the link below. Copyright @ 2013 Sage Publications.The Problem - In this case study we see a move away from orthodox views of school leadership as “headship” to a more contemporary model of educational leadership wherein we note a departure from functional, curricula-based school leadership toward more human resource development (HRD) approaches. The aim of this study was to consider the effectiveness of an educational development program for middle leaders within an educational establishment. The Solution - We examined the impact of a bespoke higher education leadership development intervention in Leadership (and Change) on the formation and cohesiveness of a newly formed innovative leadership structure. The Stakeholders - The leadership development intervention was designed through a tripartite collaboration including a university, senior school leaders, and staff. The intervention was designed to shift leadership from individual leader agency to interdependent human leadership agency. Through tripartite evaluation we uncover leadership development praxis that transcends the boundaries of conventional educational leadership and reemphasizes the benefits of bridging the academic/practitioner divide and the application of theory to praxis
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