Tungsten thermal neutron dosimeter

Tungsten-185 activity, which is produced by neutron activation of tungsten-184, determines thermal neutron flux. Radiochemical separation methods and counting techniques for irradiated tungsten provide accurate determination of the radiation exposure

Integrating multiple representations: fighting asthma

This paper seeks to engage debates about integrating pluralisms regarding multiple forms/representations and how they might function smoothly if they are closely aligned. This paper offers, narrative poetry with an artistic impression aimed at seeing how these might interact with each other. Like poetry, visual images are unique and can evoke particular kinds of emotional and visceral responses. By offering narrative poetry together with an artistic representation it is not meant to de-value the importance of either, but it is aimed at seeing how these arts-based methods and creative analytical practices might unite as a narrative to offer knew ways of ‘knowing’ and ‘seeing

How carbon vacancies can affect the properties of group IV color centers in diamond: A study of thermodynamics and kinetics

Recently there has been much interest in using Group IV elements from the Periodic Table to fabricate and study X$V$ color centers in diamond where X = Si, Ge, Sn, or Pb and $V$ is a carbon vacancy. These Group IV color centers have a number of interesting spin and optical properties which could potentially make them better candidates than N$V^-$ centers for important applications in quantum computing and quantum information processing. Unfortunately, the very same ion implantation process that is required to create these X$V$ color centers in diamond necessarily also produces many carbon vacancies ($V_{\rm C}$) which can form complexes with these color centers ($V_{\rm C}-$X$V$) that can dramatically affect the properties of the isolated X$V$ color centers. The main focus of this work is to use density-functional theory (DFT) to study the thermodynamics and kinetics of the formation of these $V_{\rm C}-$X$V$ complexes and to suggest experimental ways to impede this process such as varying the Fermi level of the host diamond material through chemical doping or applying an external electrical bias. We also include a discussion of how the simple presence of many $V_{\rm C}$ can negatively impact the spin coherence times ($T_2$) of Group IV color centers through the presence of acoustic phonons.Comment: 19 pages, 7 figure

Implications of Budget Reconciliation for Commodity Programs

Agricultural and Food Policy,

Highly nonlinear dynamics in a slowly sedimenting colloidal gel

We use a combination of original light scattering techniques and particles with unique optical properties to investigate the behavior of suspensions of attractive colloids under gravitational stress, following over time the concentration profile, the velocity profile, and the microscopic dynamics. During the compression regime, the sedimentation velocity grows nearly linearly with height, implying that the gel settling may be fully described by a (time-dependent) strain rate. We find that the microscopic dynamics exhibit remarkable scaling properties when time is normalized by strain rate, showing that the gel microscopic restructuring is dominated by its macroscopic deformation.Comment: Physical Review Letters (2011) xxx