89,815 research outputs found

    Studying pion effects in the quark propagator

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    Within the framework of Schwinger-Dyson and Bethe-Salpeter equations we investigate the importance of pions for the quark-gluon interaction. To this end we choose a truncation for the quark-gluon vertex that includes intermediate pion degrees of freedom and adjust the interaction such that unquenched lattice results for various current quark masses are reproduced. The corresponding Bethe-Salpeter kernel is constructed from constraints by chiral symmetry. After extrapolation to the physical point we find a considerable contribution of the pion back reaction to the quark mass function as well as to the chiral condensate. The quark wave function is less affected.Comment: Talk given at 11th International Conference on Meson-Nucleon Physics and the Structure of the Nucleon (MENU 2007), Julich, Germany, 10-14 Sep 200

    The Power of the Covenant Idea for Leadership, Reform, and Ethical Behavior

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    The study of leadership is awash with numerous concepts, many of which overlap. To the student and the scholar, finding a starting point and integrative theme for leadership ideas which extend from interpersonal to organizational contexts can be dizzying. This paper proposes the idea of covenant as a unifying metaphor for these valuable and often overlapping leadership ideas. The covenantal approach has had a tremendous impact on the history of Western legal and perhaps, more importantly, social and cultural thought and therefore might offer us a realistic and practical approach to effective leadership. In particular, we will see that a covenantal model emphasizes the following: 1) An ethos of empowerment, mutual care, and mutual accountability; 2) A leadership style of servant leadership; 3) A process of participative decision-making; 4) A structure of non-centralization; and 5) A culture of spirituality in the workplace

    Workforce Intermediaries: Powering Regional Economies in the New Century

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    Examines the role of workforce intermediary organizations in developing local strategies and funding, and coordinating the efforts of stakeholders in regional economic development. Outlines the qualities of successful workforce intermediary organizations

    The Road to Good Employment Retention: Three Successful Programs From the Jobs Initiative

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    Looks at long-term job retention by low-skilled individuals. Profiles three job retention initiatives with high success rates -- two in Seattle, and one in St. Louis

    Evacuation of coal from hoppers/silos with low pressure pneumatic blasting systems

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    The need for an efficient, economical, effective and quiet device for moving coal and other difficult bulk solids was recognized. Thus came the advent of the low pressure pneumatic blasting system - a very efficient means of using a small amount of plant air (up to 125 PSI) to eliminate the most troublesome material hang-ups in storage containers. This simple device has one moving part and uses approximately 3% of the air consumed by a pneumatic vibrator on the same job. The principle of operation is very simple: air stored in the unit's reservoir is expelled directly into the material via a patented quick release valve. The number, size, and placement of the blaster units on the storage vessel is determined by a series of tests to ascertain flowability of the problem material. These tests in conjunction with the hopper or silo configuration determine specification of a low pressure pneumatic blasting system. This concept has often proven effective in solving flow problems when all other means have failed

    Interleaving device

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    An interleaving device for processing energy signals between various logic devices has a first number of spaced energy carrying layer mateials. Each of the first layer materials has a number of juxtaposed conduits passing energy signals through which are passed. Each of the conduits has a longitudinal axis substantially parallel to a diagonal of each of the first layers. A second group of energy carrying materials is arranged between adjacent ones of the spaced first layer materials. Each of the second layer materials has a number of juxtaposed conduits through which the energy signals are also passed. Each of the conduits in the second layer has a longitudinal axis substantially parallel to a diagonal of each of the second layer materials and substantially perpendicular to the axes of the conduits of the first layer materials

    Results of the second flight test of the Loran-C receiver/data collection system

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    The components of the Loran-C navigation system which were developed thus far are a phase-locked-loop receiver and a microcomputer development system. The microcomputer is being used as a means of testing and implementing software to handle sensor control and navigation calculations. Currently, the microcomputer is being used to collect and record data from the receiver in addition to development work. With these components, it was possible to record receiver data over a period of time and then reduce this data to obtain statistical information. It was particularly interesting to load the equipment developed in the laboratory into an aircraft and collect data while in flight. For initial flight tests, some important considerations were how well the entire system will perform in the field, signal strength levels while on the ground and in the air, the amount of noise present, changing of signal-to-noise ratio for various aircraft configurations and maneuvers, receiver overloading due to other equipment and antennas, and the overall usefulness of Loran-C as a navigation aid

    Generalized Tukey-type distributions with application to financial and teletraffic data

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    Constructing skew and heavy-tailed distributions by transforming a standard normal variable goes back to Tukey (1977) and was extended and formalized by Hoaglin (1983) and Martinez & Iglewicz (1984). Applications of Tukey's GH distribution family - which are composed by a skewness transformation G and a kurtosis transformation H - can be found, for instance, in financial, environmental or medical statistics. Recently, alternative transformations emerged in the literature. Rayner & MacGillivray (2002b) discuss the GK distributions, where Tukey's H-transformation is replaced by another kurtosis transformation K. Similarly, Fischer & Klein (2004) advocate the J-transformation which also produces heavy tails but - in contrast to Tukey's H-transformation - still guarantees the existence of all moments. Within this work we present a very general kurtosis transformation which nests H-, K- and J-transformation and, hence, permits to discriminate between them. Applications to financial and teletraffic data are given. --

    Testing for constant correlation by means of trigonometric functions

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    A new test for constant correlation is proposed. The TC-test is derived as Lagrange multiplier (LM) test. Whereas most of the traditional tests (e.g. Jennrich, 1970, Tang, 1995 and Goetzmann, Li & Rouwenhorst, 2005) specify the unknown correlations as piecewise constant, our model-setup for the correlation coefficient is based on trigonometric functions. The simulation results demonstrate that the TC-test guarantees correct empirical size, is powerful against many alternatives and able to detect structural breaks in correlations. Finally, application of the TC-test to foreign exchange rate data over the period of 15 years is given. --
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