Microwave Nanotube Transistor Operation at High Bias

We measure the small signal, 1 GHz source-drain dynamical conductance of a back-gated single-walled carbon nanotube field effect transistor at both low and high dc bias voltages. At all bias voltages, the intrinsic device dynamical conductance at 1 GHz is identical to the low frequency dynamical conductance, consistent with the prediction of a cutoff frequency much higher than 1 GHz. This work represents a significant step towards a full characterization of a nanotube transistor for RF and microwave amplifiers.Comment: 3 pages, 4 figure

A combined R-matrix eigenstate basis set and finite-differences propagation method for the time-dependent Schr\"{od}dinger equation: the one-electron case

In this work we present the theoretical framework for the solution of the time-dependent Schr\"{o}dinger equation (TDSE) of atomic and molecular systems under strong electromagnetic fields with the configuration space of the electron's coordinates separated over two regions, that is regions $I$ and $II$. In region $I$ the solution of the TDSE is obtained by an R-matrix basis set representation of the time-dependent wavefunction. In region $II$ a grid representation of the wavefunction is considered and propagation in space and time is obtained through the finite-differences method. It appears this is the first time a combination of basis set and grid methods has been put forward for tackling multi-region time-dependent problems. In both regions, a high-order explicit scheme is employed for the time propagation. While, in a purely hydrogenic system no approximation is involved due to this separation, in multi-electron systems the validity and the usefulness of the present method relies on the basic assumption of R-matrix theory, namely that beyond a certain distance (encompassing region $I$) a single ejected electron is distinguishable from the other electrons of the multi-electron system and evolves there (region II) effectively as a one-electron system. The method is developed in detail for single active electron systems and applied to the exemplar case of the hydrogen atom in an intense laser field.Comment: 13 pages, 6 figures, submitte

Electrical conductivity of chondritic meteorites

The electrical conductivity of samples of the Murchison and Allende carbonaceous chondrites is 4 to 6 orders of magnitude greater than rock forming minerals such as olivine for temperatures up to 700 C. The remarkably high electrical conductivity of these meteorites is attributed to carbon at the grain boundaries. Much of this carbon is produced by pyrolyzation of hydrocarbons at temperatures in excess of 150 C. As the temperature increases, light hydrocarbons are driven off and a carbon-rich residue or char migrates to the grain boundaries enhancing electrical conductivity. Assuming that carbon was present at the grain boundaries in the material which comprised the meteorite parent bodies, the electrical heating of such bodies was calculated as a function of body size and solar distance during a hypothetical T-Tauri phase of the sun. Input conductivity data for the meteorite parent body were the present carbonaceous chondrite values for temperatures up to 840 C and the electrical conductivity values for olivine above 840 C

Promoting Environments that Measure Outcomes: Partnerships for Change

This paper describes the development of the PrEMO© (Promoting Environments that Measure Outcomes) program. PrEMO© is an innovative model promoting evidence-based practice (EBP) while developing capacity and quality of Level II fieldwork placements. The PrEMO© program is described from initiation to completion, including development of site-specific learning objectives, the twelve week schedule and the role of faculty mentorship. Occupational therapy (OT) students, and university OT program faculty including academic fieldwork coordinators, partner with fieldwork educators at the site to implement EBP using a data-driven decision making (DDDM) process to guide the development of evidence-based practices. PrEMO© appears to be a useful strategy for building Level II fieldwork capacity and enhancing student and fieldwork educators’ knowledge and skills about EBP and outcome measurement in routine OT practice

Accuracy of density functionals for molecular electronics: the Anderson junction

The exact ground-state exchange-correlation functional of Kohn-Sham density functional theory yields the exact transmission through an Anderson junction at zero bias and temperature. The exact impurity charge susceptibility is used to construct the exact exchange-correlation potential. We analyze the successes and limitations of various types of approximations, including smooth and discontinuous functionals of the occupation, as well as symmetry-broken approaches.Comment: 6 pages, 5 figures, submitted to Phys. Rev.

Microwave Transport in Metallic Single-Walled Carbon Nanotubes

The dynamical conductance of electrically contacted single-walled carbon nanotubes is measured from dc to 10 GHz as a function of source-drain voltage in both the low-field and high-field limits. The ac conductance of the nanotube itself is found to be equal to the dc conductance over the frequency range studied for tubes in both the ballistic and diffusive limit. This clearly demonstrates that nanotubes can carry high-frequency currents at least as well as dc currents over a wide range of operating conditions. Although a detailed theoretical explanation is still lacking, we present a phenomenological model of the ac impedance of a carbon nanotube in the presence of scattering that is consistent with these results.Comment: Added reference

Implementing the information prescription protocol in a family medicine practice: a case study.

QUESTION: Can an information prescription protocol be successfully integrated into a family medicine practice seeking to enhance patient education and self-management? SETTING: Milton Family Practice, an outpatient clinic and resident teaching site of the University of Vermont and Fletcher Allen Health Care, is located in a semirural area fifteen miles from main campus. OBJECTIVES: The objectives were to increase physicians\u27 knowledge and use of information prescriptions, sustain integration of information prescription use, and increase physicians\u27 ability to provide patient education information. METHODS: Methods used were promotion of the National Library of Medicine\u27s Information Rx, physician instruction, installation of patient and provider workstations, and a collaborative approach to practice integration. MAIN RESULTS: A post-intervention survey showed increased physician knowledge and use of the Information Rx protocol. Support procedures were integrated at the practice. CONCLUSIONS: Sustainable integration of Information Rx in a primary care clinic requires not only promotion and education, but also attention to clinic organization and procedures