Transport phenomena in nanotube quantum dots from strong to weak confinement

We report low-temperature transport experiments on single-wall nanotubes with metallic leads of varying contact quality, ranging from weak tunneling to almost perfect transmission. In the weak tunneling regime, where Coulomb blockade dominates, the nanotubes act as one-dimensional quantum dots. For stronger coupling to the leads the conductance can be strongly enhanced by inelastic cotunneling and the Kondo effect. For open contacts Coulomb blockade is completely suppressed, and the low-temperature conductance remains generally high, although we often see distinct dips in the conductance versus gate voltage which may result from resonant backscattering.Comment: 4 pages including 3 figures, for proceedings of the Moriond meeting 200

Shell filling in closed single-wall carbon nanotube quantum dots

We observe two-fold shell filling in the spectra of closed one-dimensional quantum dots formed in single-wall carbon nanotubes. Its signatures include a bimodal distribution of addition energies, correlations in the excitation spectra for different electron number, and alternation of the spins of the added electrons. This provides a contrast with quantum dots in higher dimensions, where such spin pairing is absent. We also see indications of an additional fourfold periodicity indicative of K-K' subband shells. Our results suggest that the absence of shell filling in most isolated nanotube dots results from disorder or nonuniformity.Comment: 4 pages including 4 figure

Quantum dots in suspended single-wall carbon nanotubes

We present a simple technique which uses a self-aligned oxide etch to suspend individual single-wall carbon nanotubes between metallic electrodes. This enables one to compare the properties of a particular nanotube before and after suspension, as well as to study transport in suspended tubes. As an example of the utility of the technique, we study quantum dots in suspended tubes, finding that their capacitances are reduced owing to the removal of the dielectric substrate

One-dimensional transport in bundles of single-walled carbon nanotubes

We report measurements of the temperature and gate voltage dependence for individual bundles (ropes) of single-walled nanotubes. When the conductance is less than about e^2/h at room temperature, it is found to decrease as an approximate power law of temperature down to the region where Coulomb blockade sets in. The power-law exponents are consistent with those expected for electron tunneling into a Luttinger liquid. When the conductance is greater than e^2/h at room temperature, it changes much more slowly at high temperatures, but eventually develops very large fluctuations as a function of gate voltage when sufficiently cold. We discuss the interpretation of these results in terms of transport through a Luttinger liquid.Comment: 5 pages latex including 3 figures, for proceedings of IWEPNM 99 (Kirchberg

A Research Agenda for Linked Closed Data

While it is preferable that Linked Data is published without access or licence restrictions, there will always remain certain datasets which, perhaps due to financial considerations, cannot be published as Linked Open Data. If these valuable datasets do join the Web of Linked Data, it will be as Linked Closed Data - Linked Data with access and license restrictions. In this paper, we outline a research agenda for Linked Closed Data that considers the effects that access and license restrictions may have on the Web of Linked Data. If implemented poorly, access restrictions have the potential to break URI resolvability, but even when implemented well, we can expect them to affect dataset selection processes and inter-dataset link creation rates. Additionally, there remains the technical challenge of developing and standardising access restriction and automated payment techniques for the Web of Linked Data

Consuming Linked Closed Data

The growth of the Linked Data corpus will eventually pre- vent all but the most determined of consumers from including every Linked Dataset in a single undertaking. In addition, we anticipate that the need for effective revenue models for Linked Data publishing will spur the rise of Linked Closed Data, where access to datasets is restricted. We argue that these impeding changes necessitate an overhaul of our current practices for consuming Linked Data. To this end, we propose a model for consuming Linked Data, built on the notion of continuous Information Quality assessment, which brings together a range of existing research and highlights a number of avenues for future work

Strings of Hope: The Meanings of the Violin in Jewish and Holocaust History

Title from PDF of title page, viewed on March 22, 2016Thesis advisor: Miriam Forman-BrunellVitaIncludes bibliographical references (pages 35-38)Thesis (M.A.)--Department of History. University of Missouri--Kansas City, 2015The purpose of this thesis is to examine the impact of orchestra music, specifically the violin, in concentration camps during the era of Nazi rule. What impact did the violin have on Jewish music and culture prior to Nazi domination? How did the Nazis use instrumental music to manage of the camps and control the lives of prisoners? How did the music prove to be a means of defiance against Nazi power? In an era when Nazis stripped Jews of their belongings, what did simply possessing a musical instrument mean to Jewish musicians? This study places the violin at the center of Holocaust inquiry and at the intersection of music history and Jewish history. I examine a broad body of primary sources from autobiographies to art and oral histories to photographs utilizing textual, material, and visual methods of analysis.Abstract -- List of illustrations -- Strings of hope: the meanings of the violin in Jewish and holocaust histor

Visualization of one-dimensional diffusion and spontaneous segregation of hydrogen in single crystals of VO2

Hydrogen intercalation in solids is common, complicated, and very difficult to monitor. In a new approach to the problem, we have studied the profile of hydrogen diffusion in single-crystal nanobeams and plates of VO2, exploiting the fact that hydrogen doping in this material leads to visible darkening near room temperature connected with the metal-insulator transition at 65 {\deg}C. We observe hydrogen diffusion along the rutile c-axis but not perpendicular to it, making this a highly one-dimensional diffusion system. We obtain an activated diffusion coefficient, ~0.01 e^(-0.6 eV/k_B T) cm2sec-1, applicable in metallic phase. In addition, we observe dramatic supercooling of the hydrogen-induced metallic phase and spontaneous segregation of the hydrogen into stripes implying that the diffusion process is highly nonlinear, even in the absence of defects. Similar complications may occur in hydrogen motion in other materials but are not revealed by conventional measurement techniques