503 research outputs found

    Burnout Factors of High School Basketball Coaches: An Analysis of Head Varsity Coaches in the State of Iowa

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    Current research is beginning to show evidence of athletic coaches suffering from high levels of stress and burnout within the profession. Much of this research has been conducted at the collegiate level, with little or no regard to high school coaches. The purpose of this study was three-fold. The first was to determine what factors of burnout could be identified among head varsity basketball coaches in the state of Iowa. Secondly, this study was designed to identify any difference in burnout factors across gender. This study also attempted to address a somewhat new phenomenon in coaching: the pressure and difficulties encountered when dealing with the parents of current players. By examining data, this study was designed to determine if this new problem is a significant cause of stress and burnout. A researcher designed Coaching Burnout Survey was sent to 350 head basketball coaches throughout Iowa. One hundred eighty of those surveys were addressed to head boy\u27s coaches, and 170 to head girl\u27s coaches. These coaches were asked to complete the survey and return the results as expediently as possible to the researcher. The returned surveys were then analyzed using descriptive statistical techniques along with multiple regression statistics. The findings indicated that two main predictors of burnout existed among Iowa high school basketball coaches: age and the number of sports that an individual coached. Data also found that although parental conflicts are increasing, making the job more difficult, it has not become a significant cause of stress and burnout. Insufficient data were returned in order to analyze any differences in burnout between genders

    An Artificial Immune System Strategy for Robust Chemical Spectra Classification via Distributed Heterogeneous Sensors

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    The timely detection and classification of chemical and biological agents in a wartime environment is a critical component of force protection in hostile areas. Moreover, the possibility of toxic agent use in heavily populated civilian areas has risen dramatically in recent months. This thesis effort proposes a strategy for identifying such agents vis distributed sensors in an Artificial Immune System (AIS) network. The system may be used to complement electronic nose ( E-nose ) research being conducted in part by the Air Force Research Laboratory Sensors Directorate. In addition, the proposed strategy may facilitate fulfillment of a recent mandate by the President of the United States to the Office of Homeland Defense for the provision of a system that protects civilian populations from chemical and biological agents. The proposed system is composed of networked sensors and nodes, communicating via wireless or wired connections. Measurements are continually taken via dispersed, redundant, and heterogeneous sensors strategically placed in high threat areas. These sensors continually measure and classify air or liquid samples, alerting personnel when toxic agents are detected. Detection is based upon the Biological Immune System (BIS) model of antigens and antibodies, and alerts are generated when a measured sample is determined to be a valid toxic agent (antigen). Agent signatures (antibodies) are continually distributed throughout the system to adapt to changes in the environment or to new antigens. Antibody features are determined via data mining techniques in order to improve system performance and classification capabilities. Genetic algorithms (GAs) are critical part of the process, namely in antibody generation and feature subset selection calculations. Demonstrated results validate the utility of the proposed distributed AIS model for robust chemical spectra recognition

    Exotic magnetic orders for high spin ultracold fermions

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    We study Hubbard models for ultracold bosonic or fermionic atoms loaded into an optical lattice. The atoms carry a high spin F>1/2F>1/2, and interact on site via strong repulsive Van der Waals forces. Making convenient rearrangements of the interaction terms, and exploiting their symmetry properties, we derive low energy effective models with nearest-neighbor interactions, and their properties. We apply our method to F=3/2F=3/2, and 5/2 fermions on two-dimensional square lattice at quarter, and 1/6 fillings, respectively, and investigate mean-field equations for repulsive couplings. We find for F=3/2F=3/2 fermions that the plaquette state appearing in the highly symmetric SU(4) case does not require fine tuning, and is stable in an extended region of the phase diagram. This phase competes with an SU(2) flux state, that is always suppressed for repulsive interactions in absence of external magnetic field. The SU(2) flux state has, however, lower energy than the plaquette phase, and stabilizes in the presence of weak applied magnetic field. For F=5/2F=5/2 fermions a similar SU(2) plaquette phase is found to be the ground state without external magnetic field.Comment: final version, 6 pages, 4 figures, epl forma

    Time interval distributions of atoms in atomic beams

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    We report on the experimental investigation of two-particle correlations between neutral atoms in a Hanbury Brown and Twiss experiment. Both an atom laser beam and a pseudo-thermal atomic beam are extracted from a Bose-Einstein condensate and the atom flux is measured with a single atom counter. We determine the conditional and the unconditional detection probabilities for the atoms in the beam and find good agreement with the theoretical predictions.Comment: 4 pages, 3 figure

    Collisional properties of ultracold K-Rb mixtures

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    We determine the inter-species s-wave triplet scattering length a3 for all K-Rb isotopic mixtures by measuring the cross-section for collisions between 41K and 87Rb in different temperature regimes. The positive value a3=+163(+57,-12)a0 ensures the stability of binary 41K-87Rb Bose-Einstein condensates. For the fermion-boson mixture 40K-87Rb we obtain a large and negative scattering length which implies an efficient sympathetic cooling of the fermionic species down to the degenerate regime.Comment: 4 pages, 4 figures; revised version (references added and small changes

    Exploring phase coherence in a 2D lattice of Bose-Einstein condensates

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    Bose-Einstein condensates of rubidium atoms are stored in a two-dimensional periodic dipole force potential, formed by a pair of standing wave laser fields. The resulting potential consists of a lattice of tightly confining tubes, each filled with a 1D quantum gas. Tunnel-coupling between neighboring tubes is controlled by the intensity of the laser fields. By observing the interference pattern of atoms released from more than 3000 individual lattice tubes the phase coherence of the coupled quantum gases is studied. The lifetime of the condensate in the lattice and the dependence of the interference pattern on the lattice configuration are investigated.Comment: 4 pages, 6 figure

    Hybrid apparatus for Bose-Einstein condensation and cavity quantum electrodynamics: Single atom detection in quantum degenerate gases

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    We present and characterize an experimental system in which we achieve the integration of an ultrahigh finesse optical cavity with a Bose-Einstein condensate (BEC). The conceptually novel design of the apparatus for the production of BECs features nested vacuum chambers and an in-vacuo magnetic transport configuration. It grants large scale spatial access to the BEC for samples and probes via a modular and exchangeable "science platform". We are able to produce \87Rb condensates of five million atoms and to output couple continuous atom lasers. The cavity is mounted on the science platform on top of a vibration isolation system. The optical cavity works in the strong coupling regime of cavity quantum electrodynamics and serves as a quantum optical detector for single atoms. This system enables us to study atom optics on a single particle level and to further develop the field of quantum atom optics. We describe the technological modules and the operation of the combined BEC cavity apparatus. Its performance is characterized by single atom detection measurements for thermal and quantum degenerate atomic beams. The atom laser provides a fast and controllable supply of atoms coupling with the cavity mode and allows for an efficient study of atom field interactions in the strong coupling regime. Moreover, the high detection efficiency for quantum degenerate atoms distinguishes the cavity as a sensitive and weakly invasive probe for cold atomic clouds

    Measuring the temporal coherence of an atom laser beam

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    We report on the measurement of the temporal coherence of an atom laser beam extracted from a 87^{87}Rb Bose-Einstein condensate. Reflecting the beam from a potential barrier creates a standing matter wave structure. From the contrast of this interference pattern, observed by magnetic resonance imaging, we have deduced an energy width of the atom laser beam which is Fourier limited by the duration of output coupling. This gives an upper limit for temporal phase fluctuations in the Bose-Einstein condensate.Comment: 4 pages, 3 figure

    Lifetime of double occupancies in the Fermi-Hubbard model

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    We investigate the decay of artificially created double occupancies in a repulsive Fermi-Hubbard system in the strongly interacting limit using diagrammatic many-body theory and experiments with ultracold fermions on optical lattices. The lifetime of the doublons is found to scale exponentially with the ratio of the on-site repulsion to the bandwidth. We show that the dominant decay process in presence of background holes is the excitation of a large number of particle hole pairs to absorb the energy of the doublon. We also show that the strongly interacting nature of the background state is crucial in obtaining the correct estimate of the doublon lifetime in these systems. The theoretical estimates and the experimental data are in fair quantitative agreement
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