Children's radio programs.

Thesis (M.A.)--Boston Universit

Children's radio programs.

Thesis (M.A.)--Boston Universit

Orbital stability of periodic waves in the class of reduced Ostrovsky equations

Periodic travelling waves are considered in the class of reduced Ostrovsky equations that describe low-frequency internal waves in the presence of rotation. The reduced Ostrovsky equations with either quadratic or cubic nonlinearities can be transformed to integrable equations of the Klein--Gordon type by means of a change of coordinates. By using the conserved momentum and energy as well as an additional conserved quantity due to integrability, we prove that small-amplitude periodic waves are orbitally stable with respect to subharmonic perturbations, with period equal to an integer multiple of the period of the wave. The proof is based on construction of a Lyapunov functional, which is convex at the periodic wave and is conserved in the time evolution. We also show numerically that convexity of the Lyapunov functional holds for periodic waves of arbitrary amplitudes.Comment: 34 page

BARLEY PRODUCTION COSTS: A CROSS-BORDER COMPARISON

Barley production costs are compared for five states and three Canadian provinces. A stochastic simulation, incorporating yield and exchange-rate risk, is used to characterize regional cost advantages in terms of probabilities.barley, production costs, yield risk, simulation analysis, Agricultural Finance, Production Economics,

Optimization of leaf morphology in relation to leaf water status: A theory.

The leaf economic traits such as leaf area, maximum carbon assimilation rate, and venation are all correlated and related to water availability. Furthermore, leaves are often broad and large in humid areas and narrower in arid/semiarid and hot and cold areas. We use optimization theory to explain these patterns. We have created a constrained optimization leaf model linking leaf shape to vein structure that is integrated into coupled transpiration and carbon assimilation processes. The model maximizes net leaf carbon gain (NPPleaf) over the loss of xylem water potential. Modeled relations between leaf traits are consistent with empirically observed patterns. As the results of the leaf shape-venation relation, our model further predicts that a broadleaf has overall higher NPPleaf compared to a narrowleaf. In addition, a broadleaf has a lower stomatal resistance compared to a narrowleaf under the same level of constraint. With the same leaf area, a broadleaf will have, on average, larger conduits and lower total leaf xylem resistance and thus be more efficient in water transportation but less resistant to cavitation. By linking venation structure to leaf shape and using water potential as the constraint, our model provides a physical explanation for the general pattern of the covariance of leaf traits through the safety-efficiency trade-off of leaf hydraulic design

Karajarri sketch grammar

This thesis is a reference ( or sketch) grammar of Karajarri, an Australian Aboriginal language. As such, there is no attempt to be fully comprehensive at any point, but rather to provide a broad overview of the grammar of the language. I have chosen, however, to include in the study a more detailed analysis of one aspect of the language, namely the case-marking system (based on a framework developed by Dench and Evans 1988). This overview may be a basis for further research into particular aspects of the language. The reference grammar style of this study will also be of use in understanding the texts of Karajani which already exist from past work. The analysis is based on previous work done on Karajarri, as well as a period of field research in June 1992