Single-Walled Carbon Nanotubes as Shadow Masks for Nanogap Fabrication

We describe a technique for fabricating nanometer-scale gaps in Pt wires on insulating substrates, using individual single-walled carbon nanotubes as shadow masks during metal deposition. More than 80% of the devices display current-voltage dependencies characteristic of direct electron tunneling. Fits to the current-voltage data yield gap widths in the 0.8-2.3 nm range for these devices, dimensions that are well suited for single-molecule transport measurements

Balanced electronic detection of displacement in nanoelectromechanical systems

We describe a broadband radio frequency balanced bridge technique for electronic detection of displacement in nanoelectromechanical systems (NEMS). With its two-port actuation-detection configuration, this approach generates a background-nulled electromotive force in a dc magnetic field that is proportional to the displacement of the NEMS resonator. We demonstrate the effectiveness of the technique by detecting small impedance changes originating from NEMS electromechanical resonances that are accompanied by large static background impedances at very high frequencies. This technique allows the study of important experimental systems such as doped semiconductor NEMS and may provide benefits to other high frequency displacement transduction circuits

Unstable Slope Management Program

INE/AUTC 11.1

Solutions of special asymptotics to the Einstein constraint equations

We construct solutions with prescribed asymptotics to the Einstein constraint equations using a cut-off technique. Moreover, we give various examples of vacuum asymptotically flat manifolds whose center of mass and angular momentum are ill-defined.Comment: 13 pages; the error in Lemma 3.5 fixed and typos corrected; to appear in Class. Quantum Gra

Are Investors Warned by Disclosure of Conflicts of Interest? The Moderating Effect of Investment Horizon

Financial analysts are required to disclose conflicts of interest (COI) in their research reports, but there is limited evidence on the effectiveness of COI disclosures. We investigate whether the influence of disclosing COI in analyst reports on investors' decision making depends on investment horizon. Experimental results show that short-term investors who view a COI disclosure are significantly less willing to invest in the recommended stock compared to short-term investors who do not view such a disclosure, while the presence of a COI disclosure does not significantly affect long-term investors’ willingness to invest. Results further demonstrate that the COI disclosure decreases short-term investors’ willingness to invest by reducing their perception of analysts’ trustworthiness and expertness. This study provides evidence on when and how the COI disclosure can influence investors’ behavior and enhances our understanding of investors’ reactions to cautionary disclaimers

Monocrystalline silicon carbide nanoelectromechanical systems

SiC is an extremely promising material for nanoelectromechanical systems given its large Young's modulus and robust surface properties. We have patterned nanometer scale electromechanical resonators from single-crystal 3C-SiC layers grown epitaxially upon Si substrates. A surface nanomachining process is described that involves electron beam lithography followed by dry anisotropic and selective electron cyclotron resonance plasma etching steps. Measurements on a representative family of the resulting devices demonstrate that, for a given geometry, nanometer-scale SiC resonators are capable of yielding substantially higher frequencies than GaAs and Si resonators

A New Layer Casting System for Ceramic Laser Rapid Prototyping Apparatus

In the existing Ceramic Laser Fusion system, slurry is fed on the high temperature surface of the green part; therefore, a part of water infiltrates into the green block and vaporizes before the process of layer casting. As a result, the slurry viscosity rises gradually; the quality of the layer surface is not uniform, and the green part density is uneven. The aim of present study is to develop a new layer casting system which can solve the problems mentioned above to obtain a green part with uniform surface quality and density, and to shorten the time-taken of part fabrication. The first part of the paper illustrates the major requirements and parameters of a slurry distributor; the second part describes the integration of the slurry feeding device and layer casting system. The integrated system can feed slurry and cast thin layer simultaneously; consequently, the drawbacks of the existing system can be eliminated and the time-taken of the layer casting can be shortened. A variable-frequency drive (inverter) is used to control the motor speed. The relation between the frequency and the slurry delivery can be included in the process control program to adjust the quantity in accordance with the layer thickness; hence, the waste of the slurry can be reduced.Mechanical Engineerin