Medical Errors

Overview: Time of Death: 5:07 p.m. – Proceeding the solemn afternoon of February 22nd 2003, the Santillian family listened on as doctors told them that their cherished loved one was officially pronounced brain dead and would soon have to be taken off life support. Two weeks prior to this, seventeen-year-old Jesica Santillian received the thrilling news that she had finally been matched with a heart-lung donor and would be admitted to Duke University Medical Center in early February for a double-organ transplant. After years of living in pain brought on by her failing organs, Jesica was supposed to be one of the lucky ones, that is, until an ill-fated call received an hour after the new organs had been put in turned her luck upside down. The call was from a technician in the immunology lab saying that something had gone terribly wrong; Jesica’s blood type, type O, did not match the blood type her new organs, which were type A. What that meant was that Jesica’s life was in serious danger because the antibodies in her blood would shortly start attacking and destroying her new organs. Two weeks and an odds-shattering second set of donated organs later, the near death teenager’s family said their last goodbyes as the medication that kept her heart going was discontinued and her heart took its last untimely beat seven minutes later (Kopp 1)

Diversification of Wairarapa hill country : the potential for agroforestry : a thesis presented in partial fulfilment of the requirements for the degree of Master of Agricultural Science at Massey University

The purpose of this study was to investigate the potential for agroforestry on Wairarapa Hill Country farms. It was set against a background of a marked decline in real farm income on hill country sheep and beef farms in recent years. A broad perspective on project evaluation was taken with a review of the system components presented; covering hill country farming in New Zealand, the Wairarapa, Forestry in New Zealand, and Agroforestry. The results of an intertemporal linear programming model covering a 21 year period, suggest that agroforestry can be both a profitable and feasible investment for Wairarapa Hill Country farmers. Profitability is shown to be strongly influenced by the suitability of planting sites and final timber value. With respect to feasibility, cash-flow considerations are of overriding importance. Together with factors considered outside the model, particularly the management of an integrated livestock and agroforestry property, the need for individual evaluation of each circumstance is stressed. It is recommended that significant development of agroforestry in the Wairarapa will require some form of District Association to co-ordinate planting and marketing, and provide suitable extension and management services. Further development of the model for both agroforestry and land use evaluation is suggested

Low-frequency interaction between horizontal and overturning gyres in the ocean

Author Posting. © American Geophysical Union, 2008. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geophysical Research Letters 35 (2008): L18614, doi:10.1029/2008GL035206.Low-frequency variability of the horizontal circulation in an idealized, eddy-permitting, numerical model drives the dominant mode of low-frequency variability in the meridional overturning circulation. This coupling takes place through the influence of lateral advection in the cyclonic high-latitude boundary current on the mixed layer depth along the boundary. The mean and low-frequency variability of the meridional overturning circulation are well predicted by a diagnostic estimate that assumes the downwelling is controlled by the thermal wind shear within the mixed layer along the boundary, which is in turn determined by a simple balance between lateral advection and surface cooling. The more general result is the demonstration that the mean and low frequency variability of the meridional overturning streamfunction are controlled by the baroclinic pressure gradient within the mixed layer along the boundary, which may be influenced by numerous factors such as low-frequency variability in lateral advection, wind stress, surface buoyancy fluxes, or ice melt and freshwater runoff.This work was supported by NSF grants OCE-0423975 and OCE-0726339

Control of Complex Dynamic Systems by Neural Networks

This paper considers the use of neural networks (NN's) in controlling a nonlinear, stochastic system with unknown process equations. The NN is used to model the resulting unknown control law. The approach here is based on using the output error of the system to train the NN controller without the need to construct a separate model (NN or other type) for the unknown process dynamics. To implement such a direct adaptive control approach, it is required that connection weights in the NN be estimated while the system is being controlled. As a result of the feedback of the unknown process dynamics, however, it is not possible to determine the gradient of the loss function for use in standard (back-propagation-type) weight estimation algorithms. Therefore, this paper considers the use of a new stochastic approximation algorithm for this weight estimation, which is based on a 'simultaneous perturbation' gradient approximation that only requires the system output error. It is shown that this algorithm can greatly enhance the efficiency over more standard stochastic approximation algorithms based on finite-difference gradient approximations

Boundary intensification of vertical velocity in a β-plane basin

Author Posting. © American Meteorological Society, 2005. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Physical Oceanography 35 (2005): 2487-2500, doi:10.1175/JPO2832.1.The buoyancy-driven circulation of simple two-layer models on the β plane is studied in order to examine the role of beta in determining the magnitude and structure of the vertical motions forced in response to surface heating and cooling. Both analytical and numerical approaches are used to describe the change in circulation pattern and strength as a consequence of the planetary vorticity gradient. The physics is quasigeostrophic at lowest order but is sensitive to small nonquasigeostrophic mass fluxes across the boundary of the basin. The height of the interface between the two layers serves as an analog of temperature, and the vertical velocity at the interface consists of a cross-isopycnal velocity, modeled in terms of a relaxation to a prescribed interface height, as well as an adiabatic representation of eddy thickness fluxes parameterized as lateral diffusion of interface displacement. In the numerical model the lateral eddy diffusion of heat is explicitly represented by a resolved eddy field. In the plausibly more realistic case, when the lateral diffusion of buoyancy dominates the diffusion of momentum, the major vertical velocities occur at the boundary of the basin as in earlier f-plane studies. The effect of the planetary vorticity gradient is to intensify the sinking at the western wall and to enhance the magnitude of that sinking with respect to the f-plane models. The vertical mass flux in the Sverdrup interior exactly balances the vertical flux in the region of the strong horizontal transport of the western boundary current, leaving the net flux to occur in a very narrow region near the western boundary tucked well within the western boundary current. On the other hand, if the lateral diffusion of heat is arbitrarily and unrealistically eliminated, the vertical mass flux is forced to occur in the interior. The circulation pattern is extremely sensitive to small net inflows or outflows across the basin perimeter. The cross-basin flux determines the interface height on the basin’s eastern boundary and affects the circulation pattern across the entire basin.This research was supported in part by grants from the National Science Foundation OCE-9901654 (JP) and OCE-0240978, and Office of Naval Research Grant N00014-03-0338 (MAS)

A numerical study of three-dimensional vortex breakdown

A numerical simulation of bubble-type vortex breakdown using a unique discrete form of the full 3-D, unsteady incompressible Navier-Stokes equations was performed. The Navier-Stokes equations were written in a vorticity-velocity form and the physical problem was not restricted to axisymmetric flow. The problem was parametized on a Rossby- Reynolds-number basis. Utilization of this parameter duo was shown to dictate the form of the free-field boundary condition specification and allowed control of axial breakdown location within the computational domain. The structure of the breakdown bubble was studied through time evolution plots of planar projected velocity vectors as well as through plots of particle traces and vortex lines. These results compared favorably with previous experimental studies. In addition, profiles of all three velocity components are presented at various axial stations and a Fourier analysis was performed to identify the dominant circumferential modes. The dynamics of the breakdown process were studied through plots of axial variation of rate of change of integrated total energy and rate of change of integrated enstrophy, as well as through contour plots of velocity, vorticity and pressure

Improving Information Sharing: Local Fusion Centers and Their Role in the Intelligence Cycle

Abstract My Master’s Project focuses on local fusion centers and the need for improved information sharing practices among law enforcement partners. After the tragic event of September 11th in 2001, the Department of Homeland Security and the Department of Justice recognized a communication gap between law enforcement agencies and a lack of effective information sharing efforts. Fusion centers play a significant role in supporting both criminal and terrorist investigations due to their ability to act as a conduit between various law enforcement partners. Due to their important responsibilities as information sharing hubs that provide valuable analysis and dissemination of information and intelligence, it is essential to enhance information practices among the centers. My Master’s Project details a strategy that will assist in advancing information sharing capabilities among local fusion centers to better detect, investigate, mitigate, and avert threats. Specifically, this paper proposes a two-part strategy that entails strengthening current partnerships among fusion centers and law enforcement agencies and developing and implementing a standardized training program for intelligence analysts. Through improved collaborative efforts, fusion centers will be able to better identify, mitigate, and prevent threats to ensure public safety and the security of the country