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

Electron transport through rectifying self-assembled monolayer diodes on silicon: Fermi level pinning at the molecule-metal interface

We report the synthesis and characterization of molecular rectifying diodes on silicon using sequential grafting of self-assembled monolayers of alkyl chains bearing a pi group at their outer end (Si/sigma-pi/metal junctions). We investigate the structure-performance relationships of these molecular devices and we examine to what extent the nature of the pi end-group (change in the energy position of their molecular orbitals) drives the properties of these molecular diodes. For all the pi-groups investigated here, we observe rectification behavior. These results extend our preliminary work using phenyl and thiophene groups (S. Lenfant et al., Nano Letters 3, 741 (2003)).The experimental current-voltage curves are analyzed with a simple analytical model, from which we extract the energy position of the molecular orbital of the pi-group in resonance with the Fermi energy of the electrodes. We report the experimental studies of the band lineup in these silicon/alkyl-pi conjugated molecule/metal junctions. We conclude that Fermi level pinning at the pi-group/metal interface is mainly responsible for the observed absence of dependence of the rectification effect on the nature of the pi-groups, even though they were chosen to have significant variations in their electronic molecular orbitalsComment: To be published in J. Phys. Chem.

Seismotectonic, structural, volcanologic, and geomorphic study of New Zealand; indigenous forest assessment in New Zealand; mapping, land use, and environmental studies in New Zealand, volume 2

The author has identified the following significant results. Ship detection via LANDSAT MSS data was demonstrated. In addition, information on ship size, orientation, and movement was obtained. Band 7 was used for the initial detection followed by confirmation on other MSS bands. Under low turbidity, as experienced in open seas, the detection of ships 100 m long was verified and detection of ships down to 30 m length theorized. High turbidity and sea state inhibit ship detection by decreasing S/N ratios. The radiance effect from snow of local slope angles and orientation was also studied. Higher radiance values and even overloading in three bands were recorded for the sun-facing slope. Local hot spots from solar reflection appear at several locations along transect D-C in Six Mile Creek Basin during September 1976

“The first man on the street” - tracing a famous Hilbert quote (1900) back to Gergonne (1825)

A short, catchy, and in its content somewhat exaggerated, quote allows us to draw a connection through three-quarters of a century between two leaders of mathematics who apparently held somewhat similar philosophical, pedagogical, and political views. In addition to providing some new facets to the biographies of Gergonne and Hilbert, our article relates to increasing demands for the dissemination of mathematical knowledge and to corresponding structural changes within mathematics during the 19th century

Eucalyptus oils: a review of production and markets (NRI Bulletin 56)

The bulletin provides information on the technical and economic aspects of the production of steam-volatile oils from eucalyptus leaf, including the collection or harvesting of the leaf and its distillation. It also reviews recent trends in the world market for eucalyptus oils. It is intended for prospective new producers of eucalyptus oil as well as organizations and individuals appraising projects involving its production. It is particularly intended for those in developing countries

Projectile insets and backed pieces from the Upper Magdalenian of La Madeleine (Tursac, Dordogne, France), new data from lithic technology

The technological and morphological reviewing of the backed bladelets and lithic points from the Peyrony and Bouvier series led us to question the status and role of these particular objects in the hunting equipment of the last Magdalenian people.Firstly, from a technological view point, a great flexibility in the production schemes characterizes the conception of backed bladelets as the methods of debitage and transformation of blanks into backed pieces vary but follow the same strict criteria as to their aim.Bladelet debitage at La Madeleine clearly aims at the production of tapered blanks, a complementary retouch adjusting the outline of the objects if necessary (edge, proximal or distal extremities). In some cases, this complementary retouch clearly modifies the blank morphology and could then take part in the making of particular types of backed bladelets. The schemes of retouch of these objects evolve progressively but clearly during the occupation of the shelter. The evolution of the lithic insets retouch schemes is clearly more effective during the Magdalenian V and VI, when first curved-backed points, then shouldered points are made, and harpoon technology develops in antler working, emphasizing the evolution in the conception of the hunting equipment. This evolution could be the result of a change in status of previous conceptions of projectile points, which no longer represent the only technical options. The greater care taken in the shaping of some bladelets could come within the intent of better defining the role of the hunting equipment existing before the introduction of new projectile points. Their evolution could then be part of a global modification of Magdalenian hunting equipment and capture techniques

Spatially Resolved Molecular Hydrogen Emission in the Inner 200AU Environments of Classical T Tauri Stars

We present 2.0-2.4micron integral field spectroscopy at adaptive optics spatial resolution (~0.''1) obtained with the Near-infrared Integral Field Spectrograph (NIFS) at Gemini North Observatory of six Classical T Tauri stars: T Tau, DG Tau, XZ Tau, HL Tau, RW Aur and HV Tau C. In all cases, the v=1-0 S(1) (2.12 micron) emission is detected at spatially extended distances from the central stars. The bulk of the H_2 emission is typically not spatially coincident with the location of continuum flux. Multiple transitions detected in the K-band spectra show that H_2 level populations are typical of gas in thermal equilibrium with excitation temperatures in the 1800K-2300 K range. Three of the stars have H_2 velocity profiles that are centered at the stellar radial velocity, and three show velocity shifts with respect to the system. Each of the stars studied here show observed excitation temperatures, spatial extents, and kinematics of the H_2 that are most consistent with shock excited emission from the inner regions of the known Herbig-Haro energy flows or from wide-angle winds encompassing the outflows rather than predominantly from UV or X-ray stimulated emission from the central stars. The data presented in this study highlights the sensitivity of adaptive optics-fed integral field spectroscopy for spatially resolving emission line structures in the environments of bright young stars.Comment: 50 pages, 13 Figures. Accepted for publication in the Astrophysical Journal. Full Resolution paper available at: http://www.astro.sunysb.edu/tracy/pubs/Beck07.pd