9,573 research outputs found

    Giant ultrafast Kerr effect in type-II superconductors

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    We study the ultrafast Kerr effect and high-harmonic generation in type-II superconductors by formulating a new model for a time-varying electromagnetic pulse normally incident on a thin-film superconductor. It is found that type-II superconductors exhibit exceptionally large χ(3)\chi^{(3)} due to the progressive destruction of Cooper pairs, and display high-harmonic generation at low incident intensities, and the highest nonlinear susceptibility of all known materials in the THz regime. Our theory opens up new avenues for accessible analytical and numerical studies of the ultrafast dynamics of superconductors

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    Dilemma In Development, Education And Employment: An Analysis Of Zimbabwe, Tanzania And Kenya

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    A Zambezia journal article.1979 was a year of impending change — change that was without form or concept. Speculation was rife while planners anxiously awaited policy direction. At that time we felt the need to point out certain realities in Zimbabwe’s education and employment potentiality, and to distinguish facts from the fantasies. In this paper we have identified four major premises which underlie existing educational and employment strategies. We call these ‘conventional wisdoms’; and in them we have tried to pin down the implicit assumptions which too often are taken as ‘givens’. These conventional wisdoms can be summarized as follows: 1. Resources to satisfy the demand for education will be available when the war stops and aid flows in. 2. Education will generate the required wealth and development. 3. People are unemployed because they do not have enough education or training. 4. In the fields of education and employment all that we need to solve our development problems is more of the same

    A new tissue test for accurate diagnosis of copper deficiency in cereals

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    Copper deficiency in ceereals can now be accurately diagnosed using tissue analysis

    Symptoms and treatment of copper deficiency of wheat

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    Copper deficiency in wheat is still common but may not be easily noticed

    Continuous Leg Cycling Ergometry Prescribed at Identical Relative Power Output Elicits Different Physiological Responses Versus Arm Cycle Ergometry

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    PURPOSE: The aim of this study was to compare physiological and perceptual responses to progressive moderate intensity continuous exercise (MICE) between leg (LCE) and arm cycle ergometry (ACE). METHODS: Seventeen active men and women (age and percent body fat = 26 ± 7 yr and 18 ± 3 %) initially performed graded exercise on each modality to assess maximal oxygen uptake (VO2max) and peak power output (PPO). Using a randomized crossover design, they subsequently performed 45 min of MICE consisting of three 15 min bouts at 20, 40, and 60 % PPO on each modality. Gas exchange data (VO2, VCO2, VE, and respiratory exchange ratio (RER), heart rate (HR), blood lactate concentration (BLa), affective valence, and rating of perceived exertion (RPE) were acquired during each bout. RESULTS: Compared to ACE, LCE revealed significantly higher (p \u3c 0.05) peak (94 ± 6 vs. 88 ± 9 %HRmax, d = 0.81) and mean HR (73 ± 6 vs. 66 ± 6 %HRmax, d = 1.20) and VO2 (54 ± 5 vs. 50 ± 7 %VO2max, d = 0.68). Time spent above 70 (22 ± 7 vs. 15 ± 8 min, d = 1.03) and 80 %HRmax (15 ± 6 vs. 9 ± 6 min, d = 1.04) was significantly greater with LCE versus ACE. LCE revealed significantly higher BLa versus ACE (5.5 ± 2.0 vs. 4.7 ± 1.5 mM, d = 0.48). CONCLUSIONS: These results exhibit that progressive leg cycling at identical intensities elicits a greater cardiometabolic stimulus than arm ergometry. Moreover, leg cycling leads to greater duration spent at intensities between 70 – 89 %VO2max which may have application to selecting specific exercise modes when prescribing MICE to increase cardiorespiratory fitness. Lastly, use of %PPO led to participants being classified in different intensity domains which merits prescribing MICE according to various threshold measures rather than relative intensities acquired from incremental exercise

    Observables in the Decays of B to Two Vector Mesons

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    In general there are nine observables in the decay of a B meson to two vector mesons defined in terms of polarization correlations of these mesons. Only six of these can be detected via the subsequent decay angular distributions because of parity conservation in those decays. The remaining three require the measurement of the spin polarization of one of the decay products.Comment: 12 pages, no figur

    The Unfulfilled Potential of Data-Driven Decision Making in Agile Software Development

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    With the general trend towards data-driven decision making (DDDM), organizations are looking for ways to use DDDM to improve their decisions. However, few studies have looked into the practitioners view of DDDM, in particular for agile organizations. In this paper we investigated the experiences of using DDDM, and how data can improve decision making. An emailed questionnaire was sent out to 124 industry practitioners in agile software developing companies, of which 84 answered. The results show that few practitioners indicated a widespread use of DDDM in their current decision making practices. The practitioners were more positive to its future use for higher-level and more general decision making, fairly positive to its use for requirements elicitation and prioritization decisions, while being less positive to its future use at the team level. The practitioners do see a lot of potential for DDDM in an agile context; however, currently unfulfilled
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