1,572 research outputs found
Anisotropy of Imbalanced Alfvenic Turbulence in Fast Solar Wind
We present the first measurement of the scale-dependent power anisotropy of
Elsasser variables in imbalanced fast solar wind turbulence. The dominant
Elsasser mode is isotropic at lower spacecraft frequencies but becomes
increasingly anisotropic at higher frequencies. The sub-dominant mode is
anisotropic throughout, but in a scale-independent way (at higher frequencies).
There are two distinct subranges exhibiting different scalings within what is
normally considered the inertial range. The low Alfven ratio and shallow
scaling of the sub-dominant Elsasser mode suggest an interpretation of the
observed discrepancy between the velocity and magnetic field scalings. The
total energy is dominated by the latter. These results do not appear to be
fully explained by any of the current theories of incompressible imbalanced MHD
turbulence.Comment: 5 pages, 2 figure
The Weights of Young African Children in a Township in Rhodesia
A CAJM article on the standard weight of Zimbabwean (Rhodesian) children vis-a-vis the avarage incomes of their parents.No standards of normal weight for young children exist for the African population in Rhodesia. Ford (1964) suggested that the Havard Standards (Stuart and Stevenson, 1959) could be used as a guide in assessing malnutrition in different ethnic groups when no local standards of reference are available. This idea has been further elaborated by Jelliffe (1966), who suggested a General Standard of Reference, which was derived from the Havard data. This study establishes a standard for African children in Rhodesia and also compares the weight-for-age curve of these young children of mixed genetic background with that derived from the Havard data
Modified Contactor for Experimental Studies of Mass Transfer and Chemical Reaction Across a Liquid-Liquid Interface
A Modified Stirred-Cell Type Contactor Has Been Designed and Tested for its Use in Experimental Investigations of Mass Transfer and Chemical Reaction in Liquid-Liquid Systems. its Design overcomes the Shortcomings of Previously Proposed Contactors. It is Easy to Operate and Has the Ability to Investigate the Effect of a Wide Range of Operating Conditions. the Mixing Performance of the Contactor Was Tested using a Dye Injection and a Tracer Technique. Experiments to Evaluate Mass-Transfer Coefficients Across a Liquid-Liquid Interface Have Been Conducted to Determine its Effectiveness. the Results Verified that the Contactor Could Be Successfully Employed as a Useful Experimental Research Apparatus
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Compressed Statistical Testing and Application to Radar
We present compressed statistical testing (CST) with an illustrative application to radar target detection. We characterize an optimality condition for a compressed domain test to yield the same result as the corresponding test in the uncompressed domain. We demonstrate by simulation that under high SNR, a likelihood ratio test with compressed samples at 3.3x or even higher compression ratio can achieve detection performance comparable to that with uncompressed data. For example, our compressed domain Sample Matrix Inversion test for radar target detection can achieve constant false alarm rate (CFAR) performance similar to the corresponding test in the raw data domain. By exploiting signal sparsity in the target and interference returns, compressive sensing based CST can incur a much lower processing cost in statistical training and decision making, and can therefore enable a variety of distributed applications such as target detection on resource limited mobile devices.Engineering and Applied Science
Rwanda\u27s Miracle: From Genocide and Poverty to Peace and Economic Prosperity
The purpose of this thesis was to examine how liberalization and the introduction of pro-poor policies can be successful in post-conflict countries using the Rwanda coffee market as a case study. My research supports the notion that economic development, political stability and peace can be a result of liberalization when policies that are pro-poor and focus on the largest sector of the population are created. The study examines why and how Rwanda chose to liberalize their economy in the way they did by focusing on the intentions of the actors and the effects their actions have had on the coffee market and country as a whole. The findings suggest that Rwanda’s coffee market liberalization has been successful and has contributed to stability and economic development in Rwanda. The conclusion indicates that pro-poor liberalization policies with the assistance from a variety of actors and institutions can lead developing countries on the path to development in ways the international community has not seen before
An Experimental Overview of Results Presented at SQM 2006
I have been asked to give an critical overview on the experimental results
shown in the conference with a emphasis of what has been learned and the
challenges that are ahead in trying to understand the physics of the strongly
interacting quark-gluon plasma. I will not try to summarize all of the results
presented, rather I will concentrate primarily on RHIC data from this
conference. Throughout this summary, I will periodically review some of the
previous results for those not familiar with the present state of the field.Comment: 15 pages, 12 Figure
Evaluating the Agronomic Feasibility of Planting late Season Corn for Feedlot Cattle
Yield, Ib/acre, bushel weight (BD), Ib/bu, relative maturity (RELMAT), chemical composition and in vitro dry matter digestibility (IVDMD) were used to screen corn varieties In = 20) of varying maturities grown under the stress of a shortened growing season. Corn varieties were planted in late June of 1996. Whole shell corn (WSC) and ear corn (EC) were harvested. Bushel weight was quantified on WSC. Yields for WSC, and EC were 1941 + 706 and 2307 ± 997 Ib DM/acre, respectively. Whole shell corn and EC were sorted into yield (YGP) groups. Whole shell corn yields were 2942 ± 248, 2305 ± 138, and 1292 ± 343 Ib DM/acre for YGPI through YGP3, respectively. The EC yields were 3740 ± 207, 2980 ± 208, 1897 ± 235 and 1139 ± 455 Ib DM1 acre for YGP 1 through 4, respectively. For WSC, YGP 1, YGP 2 and YGP 3 produced 2529, 1956 and 1099 Ib TDN/ac, respectively. Ear corn YGP 1, YGP 2, YGP 3 and YGP 4 produced 2980, 2180, 1437 and 780 Ib of TDN/ac, respectively. Increased yield in corn varieties grown under the stress of a shortened growing season was attributed to an increase in starch content. Even so, digestibility and energy content were not related (P \u3e .05) to yield or BD. Relative maturity did not influence (P \u3e .05) chemical composition, digestibility or energy content. Results suggest that while selecting earlier maturing corn for short growing seasons improves yields, it gives no advantage to feed value. Bushel weight, yield or maturity date should not be used as single criteria when predicting feed value of corn grown under the stress of a shortened growing season
Anisotropy of Solar Wind Turbulence between Ion and Electron Scales
The anisotropy of turbulence in the fast solar wind, between the ion and
electron gyroscales, is directly observed using a multispacecraft analysis
technique. Second order structure functions are calculated at different angles
to the local magnetic field, for magnetic fluctuations both perpendicular and
parallel to the mean field. In both components, the structure function value at
large angles to the field S_perp is greater than at small angles S_par: in the
perpendicular component S_perp/S_par = 5 +- 1 and in the parallel component
S_perp/S_par > 3, implying spatially anisotropic fluctuations, k_perp > k_par.
The spectral index of the perpendicular component is -2.6 at large angles and
-3 at small angles, in broad agreement with critically balanced whistler and
kinetic Alfven wave predictions. For the parallel component, however, it is
shallower than -1.9, which is considerably less steep than predicted for a
kinetic Alfven wave cascade.Comment: 4 pages, 4 figures, replaced to match published versio
A Generalized Diffusion Tensor for Fully Anisotropic Diffusion of Energetic Particles in the Heliospheric Magnetic Field
The spatial diffusion of cosmic rays in turbulent magnetic fields can, in the
most general case, be fully anisotropic, i.e. one has to distinguish three
diffusion axes in a local, field-aligned frame. We reexamine the transformation
for the diffusion tensor from this local to a global frame, in which the Parker
transport equation for energetic particles is usually formulated and solved.
Particularly, we generalize the transformation formulas to allow for an
explicit choice of two principal local perpendicular diffusion axes. This
generalization includes the 'traditional' diffusion tensor in the special case
of isotropic perpendicular diffusion. For the local frame, we motivate the
choice of the Frenet-Serret trihedron which is related to the intrinsic
magnetic field geometry. We directly compare the old and the new tensor
elements for two heliospheric magnetic field configurations, namely the hybrid
Fisk and the Parker field. Subsequently, we examine the significance of the
different formulations for the diffusion tensor in a standard 3D model for the
modulation of galactic protons. For this we utilize a numerical code to
evaluate a system of stochastic differential equations equivalent to the Parker
transport equation and present the resulting modulated spectra. The computed
differential fluxes based on the new tensor formulation deviate from those
obtained with the 'traditional' one (only valid for isotropic perpendicular
diffusion) by up to 60% for energies below a few hundred MeV depending on
heliocentric distance.Comment: 8 pages, 6 figures, accepted in Ap
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