1,899 research outputs found

    Development of a 9.3 micrometer CW LIDAR for the study of atmospheric aerosol

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    This report provides a brief summary of the basic requirements to obtain coherent or heterodyne mixing of the optical radiation backscattered by atmospheric aerosols with that from a fixed frequency source. The continuous wave (CW) mode of operation for a coherent lidar is reviewed along with the associated lidar transfer equation. A complete optical design of the three major subsystems of a CW, coherent lidar is given. Lens design software is implemented to model and optimize receiver performance. Techniques for the opto-mechanical assembly and some of the critical tolerances of the coherent lidar are provided along with preliminary tests of the subsystems. Included in these tests is a comparison of the experimental and the theoretical average power signal-to-noise ratio. The analog to digital software used to evaluate the power spectrum of the backscattered signal is presented in the Appendix of this report

    Promoting Fairness in the Workplace: Identifying and Overcoming the Barriers to Managerial Fairness in Organizations

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    Research examining “justice as a dependent variable” has largely focused on examining the factors that can promote fairness in the workplace whereas significantly less attention has been devoted to understanding the barriers and obstacles that can exist throughout the fairness process. This is an important gap in the literature because the absence of fairness can also have considerable implications for organizations. In this dissertation, I argue that it is important to adopt a “barriers to fairness” approach that sheds more light on how these obstacles can affect managers’ fair behavior. Specifically, I present a typology of the different barriers to fairness managers may experience in the workplace and three manuscripts that contribute to our understanding of the “barriers to fairness” approach. Manuscripts 1 and 2 empirically examine (a) two different barriers (i.e., low trait empathy and ego depletion, respectively) that can significantly affect managers’ enactment of fairness and (b) how these barriers can be overcome using targeted interventions. Manuscript 3 is a theoretical piece that outlines how and when enacting fairness can affect managers at each phase of the fairness process with a specific focus on how enacting fairness can increase managers’ experience of depletion. I conclude with a discussion of the general theoretical, methodological, and practical implications of this dissertation as well as future research directions associated with a “barriers to fairness” approach

    St. Patrick Inspires a Shamrock Luncheon

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    The March hostess who is looking for something different may well · take advantage of the possibilities offered by St. Patrick\u27s Day. A green and white color scheme, besides commemorating the venerable Irishman, is very dainty and suggestive of the spring season

    TASK DECOMPOSITION AND THE HIGH PERFORMANCE JUNIOR TENNIS SERVE

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    To develop consistency in the toss placement and racket trajectory, coaches often decompose the serve and practise it in separate parts. This study compared the kinematics of the ball toss as part of the discrete serve skill and when the skill was decomposed. A 22 camera VICON MX motion analysis system, operating at 250 Hz, captured racket and ball kinematics of 5 elite junior players hitting flat first serves (FS) directed to the ‘T’ of the deuce service box and a ball toss (BT) drill where players were instructed to perform the decomposed skill as in the FS. Paired t-tests were used to assess within-group differences. Vertical displacement of ball zenith increased significantly (~20cm) during BT. Consistency in select racket and ball kinematics characterised the FS, while this appeared to decrease in BT

    ‘BEND IT LIKE BECKHAM’: BALL ROTATION IN THE CURVED FOOTBALL KICK

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    The objectives of this study were to quantify the 3D angular velocity and spin axes of a curved versus straight kick for goal in football. A 12 camera 250 Hz 3D Vicon motion analysis system recorded 4 semi-professional soccer players, as they performed 5 straight (S) and 10 curved (C) kicks. While the velocity of the ball was similar for both kicks (~20 m.s-1), spin rate was significantly different (S=22.6 rad.s-1; C=36.4 rad.s-1). While the level of spin for the straight kick was surprising, the elevation angle of its spin axis was significantly lower in the straight compared with curved kicks (S=30.4°; C=62.6°

    Natural and Anthropogenic Forces Acting on a Forest Lake

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    ABS1RACT-Lak~ Itasca, Minnes~ta is located within one of the more popular state parks. Since the turn of the centmy, loggmg, fire protection, and development within the watershed have put modest pressures on the ecosystem. The presence of the University of Minnesota\u27s Biological and Forestry Station on the lake has encouraged research in this region. Consequently there are numerous research reports and papers which are available _at the station\u27s library. We examined data collected over the past 25 years to see if we could detect changes ~~ the lake. We detected no changes in phytoplankton, macrophyte, zooplankton, or zoobenthos com~urnues, but ch~ges have ?ccu_rred in four species of the fish community-bluegill, walleye, black crapp~e an? northern pike. There 1s evidence for warmer temperatures during a critical period (May) for most aquatic animals. If true it will affect the biotic interactions to the extent of shifting the equilibrium of the lake

    Sex-specific fundamental and formant frequency patterns in a cross-sectional study

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    An extensive developmental acoustic study of the speech patterns of children and adults was reported by Lee and colleagues [Lee et al., J. Acoust. Soc. Am. 105, 1455-1468 (1999)]. This paper presents a reexamination of selected fundamental frequency and formant frequency data presented in their report for 10 monophthongs by investigating sex-specific and developmental patterns using two different approaches. The first of these includes the investigation of age- and sex-specific formant frequency patterns in the monophthongs. The second, the investigation of fundamental frequency and formant frequency data using the critical band rate (bark) scale and a number of acoustic-phonetic dimensions of the monophthongs from an age- and sex-specific perspective. These acoustic-phonetic dimensions include: vowel spaces and distances from speaker centroids; frequency differences between the formant frequencies of males and females; vowel openness/closeness and frontness/backness; the degree of vocal effort; and formant frequency ranges. Both approaches reveal both age- and sex-specific development patterns which also appear to be dependent on whether vowels are peripheral or non-peripheral. The developmental emergence of these sex-specific differences are discussed with reference to anatomical, physiological, sociophonetic and culturally determined factors. Some directions for further investigation into the age-linked sex differences in speech across the lifespan are also proposed

    Towards practical classical processing for the surface code

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    The surface code is unarguably the leading quantum error correction code for 2-D nearest neighbor architectures, featuring a high threshold error rate of approximately 1%, low overhead implementations of the entire Clifford group, and flexible, arbitrarily long-range logical gates. These highly desirable features come at the cost of significant classical processing complexity. We show how to perform the processing associated with an nxn lattice of qubits, each being manipulated in a realistic, fault-tolerant manner, in O(n^2) average time per round of error correction. We also describe how to parallelize the algorithm to achieve O(1) average processing per round, using only constant computing resources per unit area and local communication. Both of these complexities are optimal.Comment: 5 pages, 6 figures, published version with some additional tex

    Aharanov-Bohm excitons at elevated temperatures in type-II ZnTe/ZnSe quantum dots

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    Optical emission from type-II ZnTe/ZnSe quantum dots demonstrates large and persistent oscillations in both the peak energy and intensity indicating the formation of coherently rotating states. Furthermore, the Aharanov-Bohm (AB) effect is shown to be remarkably robust and persists until 180K. This is at least one order of magnitude greater than the typical temperatures in lithographically defined rings. To our knowledge this is the highest temperature at which the AB effect has been observed in semiconductor structures
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