Cross-Kerr interaction in a four-level atomic system

We derive the form of the cross-Kerr interaction in a four-level atomic system in the N-configuration. We use time-independent perturbation theory to calculate the eigenenergies and eigenstates of the Schrodinger equation for the system. The system is considered as a perturbation of a Raman resonant three-level lambda scheme for which exact solutions are known. We show that within the strong control field limit the cross-Kerr interaction can arise between two weak probe fields. The strength of this nonlinear coupling is several orders of magnitude larger than that achievable using optical fibres.Comment: 5 pages, resubmitted to Physical Review A with clarified style and correction to Fig

High temperature meson propagators with domain-wall quarks

We study the chiral properties of domain-wall quarks at high temperatures on an ensemble of quenched configurations. Low lying eigenmodes of the Dirac operator are calculated and used to check the extent to which the Atiyah-Singer index theorem is obeyed on lattices with finite $N_5$. We calculate the connected and disconnected screening propagators for the lowest mass scalar and pseudoscalar mesons in the sectors of different topological charge and note that they behave as expected. Separating out the would-be zero eigenmodes enables us to accurately estimate the disconnected propagators with far less effort than would be needed otherwise.Comment: LATTICE99(Finite Temperature and Density), 3 pages, 3 figure

Creating an entrepreneurial frame of mind.

This dissertation is comprised of three essays that address the question: what specific cognitions lead to the formation of entrepreneurial intentions? Essay 1, Explaining and Predicting Entrepreneurial Intentions, investigates currently theorized antecedents of entrepreneurial intentions to determine the degree to which they predict entrepreneurial intentions. Findings suggest that proximal cognitions such as feelings, desires, emotions, and attitudes predict intention formation, albeit limited to situations where entrepreneurial behavior is imminent. Additionally, distal cognitions, such as biases, heuristics, scripts and maps, although useful in explaining intentions, are of little predictive value except when predicting the distal intention to become an entrepreneur in those with no entrepreneurial experience. Overall, results indicate that the antecedents used to explain entrepreneurial intentions are of limited predictive value. Essay 2, The Role of Cognitions in the Formation of an Entrepreneurial Mindset, examines which specific core-level antecedents act to form entrepreneurial mindset and how these cognitions relate to the formation of entrepreneurial intentions. It posits that core-level cognitions related to the self (entity-schema, possible-self, and self-efficacy) lead to the formation of an entrepreneurial mindset. The essay further posits that entrepreneurial mindset is the principal antecedent to entrepreneurial intentions. This conceptual investigation culminates in the presentation of a general theory of volitional behavior. Essay 3, An Empirical Evaluation of Entrepreneurial Mindset Using the Theory of Volitional Behavior, tests to what degree entrepreneurial mindset affects the formation of entrepreneurial intentions. Results indicate that individuals who possess an entrepreneurial entity-schema, an entrepreneurial possible-self, and entrepreneurial self-efficacy, on average, tend to form an entrepreneurial mindset. Furthermore, those individuals possessing an entrepreneurial mindset are more likely to form entrepreneurial intentions and ergo, are most likely to undertake entrepreneurial behavior. When taken together, these three essays show that (1) currently theorized antecedents of entrepreneurial intentions, although useful for explaining entrepreneurial intentions, are of limited use in the prediction of intention formation. (2) Core-level cognitions, specifically those relating to the self, represent a viable means of predicting formation of an entrepreneurial mindset. (3) Entrepreneurial mindset leads to the formation of entrepreneurial intentions, which offer one possible answer to the primary research question, what specific cognitions lead to the formation of entrepreneurial intentions

Superhybrid composite blade impact studies

The feasibility of superhybrid composite blades for meeting the mechanical design and impact resistance requirements of large fan blades for aircraft turbine engine applications was investigated. Two design concepts were evaluated: leading edge spar (TiCom) and center spar (TiCore), both with superhybrid composite shells. The investigation was both analytical and experimental. The results obtained show promise that superhybrid composites can be used to make light weight, high quality, large fan blades with good structural integrity. The blades tested successfully demonstrated their ability to meet steady state operating conditions, overspeed, and small bird impact requirements

Tensile and flexural strength of non-graphitic superhybrid composites: Predictions and comparisons

Equations are presented and described which can be used to predict bounds on the tensile and flexural strengths of nongraphitic superhybrid (NGSH) composites. These equations are derived by taking into account the measured stress-strain behavior, the lamination residual stresses and the sequence of events leading to fracture. The required input for using these equations includes constituents, properties (elastic and strength), NGSH elastic properties, cure temperature, and ply stress influence coefficients. Results predicted by these equations are in reasonably good agreement with measured data for strength and for the apparent knees in the nonlinear stress-strain curve. The lower bound values are conservative compared to measured data. These equations are relatively simple and are suitable for use in the preliminary design and initial sizing of structural components made from NGSH composites

Dynamic response of damaged angleplied fiber composites

The effects of low level damage induced by monotonic load, cyclic load and/or residual stresses on the vibration frequencies and damping factors of fiber composite angleplied laminates were investigated. Two different composite systems were studied - low modulus fiber and ultra high modulus fiber composites. The results obtained show that the frequencies and damping factors of angleplied laminates made from low modulus fiber composites are sensitive to low level damage while those made from ultra high modulus composites are not. Vibration tests may not be sufficiently sensitive to assess concentrated local damage in angleplied laminates. Dynamic response determined from low-velocity impact coupled with the Fast Fourier Transform and packaged in a minicomputer can be a convenient procedure for assessing low-level damage