Growth rate of Rayleigh-Taylor turbulent mixing layers with the foliation approach

For years, astrophysicists, plasma fusion and fluid physicists have puzzled over Rayleigh-Taylor turbulent mixing layers. In particular, strong discrepancies in the growth rates have been observed between experiments and numerical simulations. Although two phenomenological mechanisms (mode-coupling and mode-competition) have brought some insight on these differences, convincing theoretical arguments are missing to explain the observed values. In this paper, we provide an analytical expression of the growth rate compatible with both mechanisms and is valide for a self-similar, low Atwood Rayleigh-Taylor turbulent mixing subjected to a constant or time-varying acceleration. The key step in this work is the introduction of {\it foliated} averages and {\it foliated} turbulent spectra highlighted in our three dimensional numerical simulations. We show that the exact value of the Rayleigh-Taylor growth rate not only depends upon the acceleration history but is also bound to the power-law exponent of the {\it foliated} spectra at large scales

Studies on the condition of water in plant systems and of the influence of the major solid constituents

No abstract available.No abstract available

Molecular dynamics simulation of high frequency (1010 to 10 12 Hz) dielectric absorption in the Hollandite Nax(Ti 8-xCrx)O16

The charge-compensating sodium ions that reside interstitially in the one-dimensional tunnels of the hollandite Nax(Ti8-xCrx)O16 are used as a simple model for a fluid. Molecular dynamics are used to calculate the motions of the ions at a range of temperatures between 200 K and 373 K. The polarization response of the system to a step-up electric field is calculated for field strengths between 7.43 MV/m and 74.3 GV/m, and converted to an ac susceptibility. A resonance absorption is found,peaking at frequencies between 4.5x1010 and 8.8x1010 Hz at 297K. The origin of the response is shown to be the anharmonically coupled ion vibrations damped by ion hopping to neighbouring sites. The relationship of the result to the experimentally observed Poley absorption is explored, and a brief comparison of the calculated dynamics to previous theoretical models is made

A COMPARISON OF SUSTAINABLE AND CONVENTIONAL FARMERS IN NORTH DAKOTA

Interviews and mail-out/mail-back surveys were conducted in 1992 with 38 conventional and 41 sustainable North Dakota farmers. The results emphasize the differences and similarities of these two types of farmers. Sustainable farms had more diverse cropping practices and were more likely to raise alternative crops like alfalfa, buckwheat, hay, millet, oats, and rye than conventional farmers. Conventional farmers were more likely to raise traditional crops like barley, sugar beets, sunflowers, and spring wheat. Conventional farmers averaged substantially higher crop yields than sustainable farmers. Three-fourths of the sustainable farmers raised livestock compared with one-half of the conventional farmers. Conventional farmers had greater equity, assets, gross farm income, and net farm income than sustainable farmers. Conventional and sustainable farmers reported nearly the same amount of satisfaction with farming as an occupation, the same stress levels, and the same perceived skill requirements.sustainable farms, conventional farms, organic, North Dakota, Environmental Economics and Policy, Farm Management,

Attitudes Toward the Environment: How Do the Attitudes of Conventional, No-Till, and Organic Farmers Compare?

One of Che key dynamics in today\u27s increased interest in alternative fanning is concern for the environment (Beus and Dunlap, 1990). Many advocates of alternative farming argue that conventional farming harms the environment and may even destroy the future of agriculture. The implicit, and often explicit, notion associated with this view is that conventional farmers are less concerned about the environment than are alternative farmers. The present study will test this notion by comparing the attitudes toward the environment of conventional farmers with two types of alternative farmers, organic and no-till. By definition, conventional farmers are those farmers who practice high-input farming, including the use of such commercial chemicals as herbicides, pesticides, fungicides, and synthetic fertilizers. Additionally, they typically practice routine tillage to supplement their chemical efforts to control weeds. In contrast, alternative farmers are those farmers who generally avoid the use either of commercial chemicals or of conventional tillage techniques. Specifically, organic farmers minimize the use of commercial chemicals, while no-till farmers minimize tillage. Presumably, the goal in switching to these alternative practices is to reduce pollution and soil erosion, so it is reasonable to expect that farmers who engage in these practices have more pro-environment attitudes than those who do not

Moving Across Rural Spaces: A Content Analysis of Contemporary Realistic Fiction Picturebooks With Rural Settings

Romanticized rural storytelling creates difficulties for rural children in finding mirrors, seeing people like themselves and places like their homes as principal characters and settings in picturebooks. The same romanticism likewise makes it unlikely for picturebook readers in cities and suburbs to find realistic windows into rural life. Despite children’s book publishers’ purposeful increases in realistic representations of children across racial and cultural groups in recent decades, realistic and diverse narratives within rural spaces remain underrepresented, if not invisible. Drawing on critical rural theory (Fulkerson & Thomas, 2014; Williams, 1973) and tenets of nostalgia and the rural idyll (Boym, 2001, 2007; Sanders, 2013), this article examines representations of rural life in picturebooks with integral rural settings, focusing on stereotypical representations of isolation, nostalgia, and rural childhoods. The analysis highlights how depictions of movement have a direct effect on how characters interact across the rural space and how movement from one place to another, or lack thereof, influences agency, time, and story endings. The authors call for more diverse books focused on rural narratives that would work to dismantle the single story that stereotypes contribute to and to do justice to the complexity and diversity of rural life