Mathematical Modelling of Hydrophilic Ionic Fertiliser Diffusion in Plant Cuticles: Lipophilic Surfactant Effects

The agricultural industry requires improved efficacy of sprays being applied to crops and weeds to reduce their environmental impact and increase financial returns. One way to improve efficacy is by enhancing foliar penetration. The plant leaf cuticle is the most significant barrier to agrochemical diffusion within the leaf. It has been noted that a comprehensive set of mechanisms for ionic active ingredient penetration through plant leaves with surfactants is not well defined and oils that enhance penetration have been given little attention. The importance of a mechanistic mathematical model has been noted previously in the literature. Two mechanistic mathematical models have been previously developed by the authors, focusing on plant cuticle penetration of calcium chloride through tomato fruit cuticles. The models included ion binding and evaporation with hygroscopic water absorption, along with the ability to vary the active ingredient concentration and type, relative humidity and plant species. Here we further develop these models to include lipophilic adjuvant effects, as well as the adsorption and desorption of compounds on the cuticle surface with a novel Adaptive Competitive Langmuir model. These modifications to a penetration model provide a novel addition to the literature. We validate our theoretical model results against appropriate experimental data, discuss key sensitivities and relate theoretical predictions to physical mechanisms. The results indicate the addition of the desorption mechanism may be one way to predict increased penetration at late times and the sensitivity of model parameters compares wells to those present in the literature

Motor brush wear measured with strain gages

Balanced bridge circuit, supplied with low-voltage direct current and connected to a readout device, measures remaining brush material, rate of brush wear, armature runout, and brush signature

The Farrell-Hsiang method revisited

We present a sufficient condition for groups to satisfy the Farrell-Jones Conjecture in algebraic K-theory and L-theory. The condition is formulated in terms of finite quotients of the group in question and is motivated by work of Farrell-Hsiang.Comment: This version is different from the published version. A number of typos and an incorrect formula for the transfer before Lemma 6.3 pointed out by Holger Reich have been correcte

Nonadiabatic control of a superconducting qubit via strong driving

Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Physics, 2008.Includes bibliographical references (leaf 43).Quantum computation offers the promise of speeding up many calculations that are intractable on classical computers, including but not limited to factoring and the simulation of quantum mechanical systems. Quantum computation is achieved by replacing the bits of a classical computer with quoits. Qubits generalize bits by allowing not only the classical states of zero and one, but also any arbitrary superposition of zero and one. These qubits are implemented as two-state systems by mapping the classical one and zero states to two orthogonal quantum states. The qubits are then manipulated by varying the Hamiltonian of the two-state systems with time. The standard method to manipulate a two-state system is to drive it weakly using Rabi dynamics. This approach is ineffective for a large scale quantum computer because the rotation is slow, and decoherence breaks the fragile state before the computation can be completed. To address this problem, we developed a method to rapidly rotate a qubit by an arbitrary angle. This is achieved by abandoning Rabi oscillations, and instead using a strong, rapidly changing field to coherently rotate the spin. We rapid drive the system through an avoided crossing and back again by giving the on diagonal term of the Hamiltonian a parabolic time dependence. In this paper, I contrast the standard method of spin rotation via Rabi oscillations with our protocol. Then, I discuss the various numerical simulations used to evaluate our protocol. Finally, I present some experimental evidence suggesting the protocol will be effective when implemented. Then, I discuss experimental findings and computational results of our method. We found regions of parameter space that allow a qubit to be rapidly rotated by any angle from zero to nearly ~r. This new protocol for arbitrary qubit rotation is a significant improvement over techniques relying on Rabi oscillations, reducing the time needed to transition qubits.(cont.) Our protocol deserves further study and refinement for its potential to speed up and, thusly, reduce the problem of decoherence in quantum computation.by Matthew W. Farrell.S.B

A synoptic description of coal basins via image processing

An existing image processing system is adapted to describe the geologic attributes of a regional coal basin. This scheme handles a map as if it were a matrix, in contrast to more conventional approaches which represent map information in terms of linked polygons. The utility of the image processing approach is demonstrated by a multiattribute analysis of the Herrin No. 6 coal seam in Illinois. Findings include the location of a resource and estimation of tonnage corresponding to constraints on seam thickness, overburden, and Btu value, which are illustrative of the need for new mining technology

The Process of Learner Centered Instruction in Adult Clientele

Using learner centered instruction (LCI), a group of beef farmers were guided to design a farm in a layout that would most effectively offer continual learning opportunities for the beef practitioners themselves. Learner centered instruction was used as the primary teaching method for the project\u27s completion. When using LCI, coupled with the correct facilitation of programs, student empowerment, and subject interest, positive experiences are more likely to result

One-Dimensional Radial Diffusion of Small Molecules (376 Da) in Bone Tissue

The flow of nutrients through any biological tissue is important to maintain homeostasis. If the transport process is understood, medical research teams can better design medications, prosthetic implants, and tissue scaffolds. Additionally, transport rates help physicians to better understand disease states and wound healing, including minor injuries such as breaks and sprains, which will aid in better diagnoses. We developed a novel method that measures the rate of diffusion in vitro, of fluorescein sodium salt. Samples were incubated at 37°C in a 5 CO2 atmosphere for various periods of time. Samples were sliced and analyzed using Image-Pro Plus and MATLAB to obtain concentration profiles. The diffusivity was estimated from the data using the model equation for one-dimensional transport in a finite medium. We found that radial diffusivity in canine bone in 1-dimension was 1.27 x 10-7±177 1.96 x 10-8 cm2/s. As a point of reference, the diffusivity of fluorescein sodium salt in PBS is 2.7 x 10-6 cm2/s. Given the average distance between a Haversian canal and an osteon radius is 250 um, our data shows it would take approximately 20 minutes for a nutrient of a weight of 376 Da to travel between the two locations. This indicates that the diffusion time of key nutrients, such as vitamin D, with molecular weight of 384 Da, would be about 20 minute

One-Dimensional Radial Diffusion of Small Molecules (376 Da) in Bone Tissue

The flow of nutrients through any biological tissue is important to maintain homeostasis. If the transport process is understood, medical research teams can better design medications, prosthetic implants, and tissue scaffolds. Additionally, transport rates help physicians to better understand disease states and wound healing, including minor injuries such as breaks and sprains, which will aid in better diagnoses. We developed a novel method that measures the rate of diffusion in vitro, of fluorescein sodium salt. Samples were incubated at 37°C in a 5 CO2 atmosphere for various periods of time. Samples were sliced and analyzed using Image-Pro Plus and MATLAB to obtain concentration profiles. The diffusivity was estimated from the data using the model equation for one-dimensional transport in a finite medium. We found that radial diffusivity in canine bone in 1-dimension was 1.27 x 10-7±177 1.96 x 10-8 cm2/s. As a point of reference, the diffusivity of fluorescein sodium salt in PBS is 2.7 x 10-6 cm2/s. Given the average distance between a Haversian canal and an osteon radius is 250 um, our data shows it would take approximately 20 minutes for a nutrient of a weight of 376 Da to travel between the two locations. This indicates that the diffusion time of key nutrients, such as vitamin D, with molecular weight of 384 Da, would be about 20 minute