11,140 research outputs found
On writing syllabaries: Three episodes of transfer
published or submitted for publicationis peer reviewe
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On the boundary-layer structure of patterns of convection in rectangular-planform containers
This paper considers the structure of steady-state solutions of the Swift–Hohenberg
equation describing convection in shallow rectangular-planform containers heated
from below. The lateral dimensions of the planform are assumed to be much larger
than the characteristic wavelength of convection. Results are restricted to patterns
composed of rolls orthogonal to the sides of the rectangle in which case convection
sets in at a critical value of the Rayleigh number in the form of rolls parallel to
the shorter sides. This primary bifurcation from the conductive state of no motion
produces a solution which subsequently undergoes a secondary bifurcation in which
the low-amplitude motion near the shorter sides is replaced locally by cross-rolls
perpendicular to the sides. This results in the formation of grain boundaries (or
domain boundaries) within the fluid which mark the division between the different
roll orientations.With increasing Rayleigh number the grain boundaries approach the sides of the
rectangle and a boundary-layer structure is formed. In the present paper the method
of matched asymptotic expansions is used to determine this boundary-layer structure
and to predict the location of the grain boundaries. An interesting feature of the
solution is that the grain boundaries develop significant curvature and bend into the
corners of the rectangle, where the local solution is also determined.The results are compared with numerical computations of the secondary solution
branch and with previous numerical and experimental work.</jats:p
Evaluation of the Water Quality Impacts of Land Application of Poultry Litter
Evaluating the effect of land application of animal waste on water quality is fraught with inherent variability due to differing infiltration rates, slope, rainfall intensity and etc . Simulated rainfall technology has been used in erosion research for decades. Generally, this technology is used on plots of sufficient size (25 x 5 m) to develop rill and interrill erosion. The object of this investigation was to adapt and modify existing rainfall simulation technology used in soil erosion research for use in evaluating water quality impacts of land application of animal waste, and to test, evaluate and demonstrate it\u27s scientific validity. State of the art simulation technology was obtained from the National Soil Erosion Research Laboratory located on the campus of Purdue University. The technology was scaled (2 x 6 m) and modified to fit into field research programs having several treatments and rep 1 i cated p 1 ots . The technology was shown to meet specification needed to produce the required raindrop size and velocity, flexibility in storm intensity, while maintaining uniformity(\u3e 0.8). Equally important, the unit is portable and fits well into labor intensive runoff work requiring replication of a variety of treatments
Sound propagation and force chains in granular materials
Granular materials are inherently heterogeneous, leading to challenges in
formulating accurate models of sound propagation. In order to quantify acoustic
responses in space and time, we perform experiments in a photoelastic granular
material in which the internal stress pattern (in the form of force chains) is
visible. We utilize two complementary methods, high-speed imaging and
piezoelectric transduction, to provide particle-scale measurements of both the
amplitude and speed of an acoustic wave in the near-field regime. We observe
that the wave amplitude is on average largest within particles experiencing the
largest forces, particularly in those chains radiating away from the source,
with the force-dependence of this amplitude in qualitative agreement with a
simple Hertzian-like model of particle contact area. In addition, we are able
to directly observe rare transient force chains formed by the opening and
closing of contacts during propagation. The speed of the leading edge of the
pulse is in quantitative agreement with predictions for one-dimensional chains,
while the slower speed of the peak response suggests that it contains waves
which have travelled over multiple paths even within just this near-field
region. These effects highlight the importance of particle-scale behaviors in
determining the acoustical properties of granular materials
Tackling disinvestment in health care services
Rising levels of demand due to ageing populations and increases in long term conditions (White 2007), increased levels of expectation amongst patients and inflationary pressure caused by the rising cost of new technologies are amongst the explanations for the funding shortfalls in government funded health systems across the world (Newhouse 1992). The challenge facing these health systems has also been intensified by the worldwide economic downturn. Within health systems, efforts have been made to increase productivity and efficiency and to control costs without reducing quality (Garner and Littlejohns 2011) but the scale of the task necessitates further action (Donaldson et al. 2010). Beyond productivity and efficiency gains the next logical step for decision makers is disinvestment in cost-ineffective services, prioritisation of funding for one service over another or what Prasad (2012) refers to as ‘medical reversal’. The aims of this study were to explore the experiences of budget holders within the English National Health Service (NHS) in their attempts to implement programmes of disinvestment, and to consider factors which influence the success (or otherwise) of this activity. This paper begins with clarification of terminology and a summary of the current state of knowledge with regard to health service disinvestment, before presenting and discussing findings. The research suggests that disinvestment activity is varied across organisations and ranges from ‘invest to save’ schemes through to ‘true disinvestment.’ Although the majority of interviewees accept that disinvestment is necessary most had made little progress at the time of interview beyond ‘picking the low hanging fruit’. Interviewees identify a number of determinants of disinvestment such as: local/national relationships, co-ordination/ collaboration and; professional understanding and support
The Effects of Habitat Fragmentation on Avian Mobbing Behavior
Habitat fragmentation has negative effects on bird species diversity, as well as reproductive success of some species. However, there is little comparative information on the effect it may have on bird behavior. For example, small forest fragments are likely to have fewer bird species and individuals. This may limit the success of mobbing as an antipredator behavior because mobbing success depends on recruiting other birds to the group. This possibility has never been tested. The objective of my study is to quantify the effects of forest size on mobbing behavior in forest-dwelling birds. Mobbing behavior was elicited in 100 randomly selected forest patches ranging in size using a model owl as a focal point. The results show that the probability of birds participating in a mobbing event increases as forest size increase (p = 0.002). The latency as which birds respond to a predator vocalization decreases as the forest size increases (p = 0.007). However, forest size had no effect on the intensity of the mobbing event, the probability of birds making alarm calls, the number of individuals participating, or the number of species participating in the mobbing event (p = 0.097, p = 0.952, p =0.1987, p =0.1983). Additionally, no mobbing events were observed in forests fragments below 0.97 hectares, suggesting that this may near a threshold forest size at which mobbing behaviors can no longer be supported
Adaptive tracking notch filter system Patent
Adaptive notch filter, using modulation techniques for reversed phase noise signa
Fibers on a graph with local load sharing
We study a random fiber bundle model with tips of the fibers placed on a
graph having co-ordination number 3. These fibers follow local load sharing
with uniformly distributed threshold strengths of the fibers. We have studied
the critical behaviour of the model numerically using a finite size scaling
method and the mean field critical behaviour is established. The avalanche size
distribution is also found to exhibit a mean field nature in the asymptotic
limit.Comment: 9 pages, 6 figures, To appear in International Journal of Modern
Physics
Phosphorus Immobilization in Poultry Litter and Litter-amended soils with Aluminum, Calcium and Iron amendments
Arkansas produces approximately one billion broilers each year. Phosphorous (P) runoff from fields receiving poultry litter is believed to be one of the primary factors affecting water quality in Northwest Arkansas. Poultry litter contains approximately 20 g P kg-1, of which about 2 g P kg-1 is water soluble. Soils that have received repeated heavy applications of litter may have water soluble P contents of as high as 10 mg P Kg-1 soil. The objective of this study was to determine if soluble P levels could be reduced in poultry litter and litter-amended soils with Al,Ca, and/or Fe amendments. Poultry litter was amended with alum, sodium aluminate, quick lime, slaked lime, calcitic limestone, dolomitic limestone, gypsum, ferrous chloride, ferric chloride, ferrous sulfate and ferric sulfate, and incubated in the dark at 25°C for one week. Three soils which had been excessively fertilized with poultry litter were amended with alum, ferrous sulfate, calcitic limestone, gypsum and slaked lime and incubated for 4 weeks at 25 °C. In the litter studies, the Ca treatments were tested with and without CaF2 additions in an attempt to precipitate fluorapatite. At the end of the incubation period, the litter and soils were extracted with deionized water and soluble reactive P (SRP) was determined. SRP levels in the poultry litter were reduced from over 2,000 mg P kg-1 litter to less than 1 mg P kg-1 litter with the addition of alum, quick lime, slaked lime, ferrous chloride, ferric chloride, ferrous sulfate and ferric sulfate under favorable pH conditions. S.RP levels in the soils were reduced from approximately 5 mg P Kg-1 soil to less than 0.05 mg P Kg-1 soil with the addition of alum and ferrous sulfate under favorable pH conditions. Gypsum and sodium aluminate reduced SRP levels in litter by 50 to 60 percent while calcitic and dolomitic limestone were even less effective. In soils, the Ca amendments were less effective than the Al and Fe amendments, although slaked lime was effective at high pH. The results of these studies suggest that treating litter and excessively fertilized soils with some of these compounds, particularly alum, could significantly reduce the amount of SRP in runoff from littered pastures. Therefore, chemical additions to reduce SRP in litter and soil may be a best management practice in situations where eutrophication of adjacent water bodies due to P runoff has been identified. Preliminary calculations indicate that this .p ractice may be economically feasible. However, more research is needed to determine any beneficial and/or detrimental aspects of this practice
Learned Hand Never Played Nintendo: A Better Way to Think about the Non-Literal, Non-Visual Software Copyright Cases
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