Biaxial extensional motion of an inertially driven radially expanding liquid sheet

We consider the inertially driven, time-dependent biaxial extensional motion of inviscid and viscous thinning liquid sheets. We present an analytic solution describing the base flow and examine its linear stability to varicose (symmetric) perturbations within the framework of a long-wave model where transient growth and long-time asymptotic stability are considered. The stability of the system is characterized in terms of the perturbation wavenumber, Weber number, and Reynolds number. We find that the isotropic nature of the base flow yields stability results that are identical for axisymmetric and general two-dimensional perturbations. Transient growth of short-wave perturbations at early to moderate times can have significant and lasting influence on the long-time sheet thickness. For finite Reynolds numbers, a radially expanding sheet is weakly unstable with bounded growth of all perturbations, whereas in the inviscid and Stokes flow limits sheets are unstable to perturbations in the short-wave limit.

Expanding Women's Worlds?: Development, Gender, and Environment in Rural Morocco

This honors thesis is an anthropological exploration of women's cooperatives in two regions of rural Morocco. Specifically, I am interested in how contemporary development projects such as the cooperative are understood by the peoples of these regions. By conducting first-hand ethnographic research among women's cooperatives in two drastically different environments of rural Morocco, I gain further insight into the roles that culture and geography play in determining the 'success' of cooperatives inlocal communities. In using the term 'success,' I will compare notions of success as used by both Western development organizations as well as local people in Morocco. I examine and analyze the very delicate and complex interaction that occurs between largely Western development agencies and local cultures particularly through the lens of gender. I will also convey the importance of an exchange of cultural practices through development projects rather than the imposition of one cultural system on another. In writing this thesis, I hope to contribute to the growing field of the anthropologyof development, a subset of cultural anthropology that examines international development practices and the economic, social, and political factors that have an impact on the local culture. I examine cooperatives from the perspectives of both the people whoparticipate in them through personal interviews as well as development institutions through an ongoing body of published literature. Focusing on gender implications that such development initiatives have on the rural cultures of Morocco, I argue that gender identities are crucial aspects of local cultures that must be addressed within development practices. On a broader scale, I argue that a deeper knowledge of local cultures is essential if development agencies are to be 'successful' in non-Western cultures.

Enhancing Sensitivity In Natural Product Nmr: Exploring Optimal Non-Uniform Sampling

Recent optimizations of NMR spectroscopy have focused their attention on innovations in new hardware, such as novel probes and higher field strengths. Only recently has the potential to enhance the sensitivity of NMR through data acquisition strategies been investigated. This thesis has focused on the practice of enhancing the signal-to-noise ratio (SNR) of NMR using non-uniform sampling (NUS). After first establishing the concept and exact theory of compounding sensitivity enhancements in multiple non-uniformly sampled indirect dimensions, a new result was derived that NUS enhances both SNR and resolution at any given signal evolution time. In contrast, uniform sampling alternately optimizes SNR (t < 1.26T2) or resolution (t~3T2), each at the expense of the other. Experiments were designed and conducted on a plant natural product to explore this behavior of NUS in which the SNR and resolution continue to improve as acquisition time increases. Possible absolute sensitivity improvements of 1.5 and 1.9 are possible in each indirect dimension for matched and 2x biased exponentially decaying sampling densities, respectively, at an acquisition time of ¿T2. Recommendations for breaking into the linear regime of maximum entropy (MaxEnt) are proposed. Furthermore, examination into a novel sinusoidal sampling density resulted in improved line shapes in MaxEnt reconstructions of NUS data and comparable enhancement to a matched exponential sampling density. The Absolute Sample Sensitivity derived and demonstrated here for NUS holds great promise in expanding the adoption of non-uniform sampling.

A Closed-Form Solution for the Optimal Time Evolution of an Exponentially Decaying Signal with Thermal Noise

The signal-to-noise ratio of a monoexponentially decaying signal exhibits a maximum at an evolution time of approximately 1.26 T-2. It has previously been thought that there is no closed-form solution to express this maximum. We report in this note that this maximum can be represented in a specific, analytical closed form in terms of the negative real branch of an inverse function known as the Lambert W function. The Lambert function is finding increasing use in the solution of problems in a variety of areas in the physical sciences. (C) 2014 Wiley Periodicals, Inc.