Effects of magnetic field gradients on the aggregation dynamics of colloidal magnetic nanoparticles.

We have used low-field (1)H nuclear-magnetic resonance (NMR) spectroscopy and molecular dynamics (MD) to investigate the aggregation dynamics of magnetic particles in ionic ferrofluids (IFFs) in the presence of magnetic field gradients. At the beginning of the experiments, the measured NMR spectra were broad and asymmetric, exhibiting two features attributed to different dynamical environments of water protons, depending on the local strength of the field gradients. Hence, the spatial redistribution of the magnetic particles in the ferrofluid caused by the presence of an external magnetic field in a time scale of minutes can be monitored in real time, following the changes in the features of the NMR spectra during a period of about an hour. As previously reported [Heinrich et al., Phys. Rev. Lett., 2011, 106, 208301], in the homogeneous magnetic field of a NMR spectrometer, the aggregation of the particles of the IFF proceeds in two stages. The first stage corresponds to the gradual aggregation of monomers prior to and during the formation of chain-like structures. The second stage proceeds after the chains have reached a critical average length, favoring lateral association of the strings into hexagonal zipped-chain superstructures or bundles. In this work, we focus on the influence of a strongly inhomogeneous magnetic field on the aforementioned aggregation dynamics. The main observation is that, as the sample is immersed in a certain magnetic field gradient and kept there for a time τinh, magnetophoresis rapidly converts the ferrofluid into an aggregation state which finds its correspondence to a state on the evolution curve of the pristine sample in a homogeneous field. From the degree of aggregation reached at the time τinh, the IFF sample just evolves thereafter in the homogeneous field of the NMR spectrometer in exactly the same way as the pristine sample. The final equilibrium state always consists of a colloidal suspension of zipped-chain bundles with the chain axes aligned along the magnetic field direction.

Dynamics of the field-induced formation of hexagonal zipped-chain superstructures in magnetic colloids.

Combining nuclear magnetic resonance and molecular dynamics simulations, we unravel the long-time dynamics of a paradigmatic colloid with strong dipole-dipole interactions. In a homogeneous magnetic field, ionic ferrofluids exhibit a stepwise association process from ensembles of monomers over stringlike chains to bundles of hexagonal zipped-chain patches. We demonstrate that attractive van der Waals interactions due to charge-density fluctuations in the magnetic particles play the key role for the dynamical stabilization of the hexagonal superstructures against thermal dissociation. Our results give insight into the dynamics of self-organization in systems dominated by dipolar interactions.

Advancing mission in the marketplace. Integrated strategic planning and budgeting helps a system remain accountable.

In the late 1980s Holy Cross Health System (HCHS), South Bend, IN, began to implement a revised strategic planning and budgeting process to effectively link the system's mission with its day-to-day operations. Leaders wanted a process that would help system employees internalize and act on the four major elements articulated in the HCHS mission statement: fidelity, excellence, empowerment, and stewardship. Representatives from mission, strategic planning, and finance from the corporate office and subsidiaries examined planning and budgeting methods. From the beginning, HCHS leaders decided that the process should be implemented gradually, with each step focusing on refining methodology and improving mission integration. As the process evolved. HCHS developed a sequence in which planning preceded budgeting. The system also developed a variety of educational and collaborative initiatives to help system employees adapt to the organization's change of direction. One critical aspect of HCHS's ongoing education is an ethical reflection process that helps participants balance ethical considerations by viewing an issue from three perspectives: social vision, multiple responsibility, and self-interest.

Focusing efforts toward the poor. A system raises its consciousness.

In 1987 the Holy Cross Health System (HCHS), South Bend, IN, appointed a Task Force on the Care of the Poor to determine whether the system was fulfilling its ministry to the poor during these times of scarce resources. Specific charges were to assess the system's qualitative and quantitative responses to the issue of caring for the poor; review the recommendations in No Room in the Marketplace: The Health Care of the Poor and assess their applicability to HCHS; and recommend management and system governance strategies that creatively address the care of the poor. After months of meetings, research, and difficult questions, the task force completed a report that is tied to The System Strategic Plan. Using strategic plan objectives in six key areas, the task force developed measurable criteria, which each system facility is expected to meet annually. The report demands a focused effort toward care of the poor and requires that the annual performance evaluations of senior managers throughout the system include an assessment of the organization's efforts to provide healthcare services to the poor. This is intended to make each senior manager consciously reflect on the implications for the poor in all actions that he or she takes.