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

Transport and Strong-Correlation Phenomena in Carbon Nanotube Quantum Dots in a Magnetic Field

Transport through carbon nanotube (CNT) quantum dots (QDs) in a magnetic field is discussed. The evolution of the system from the ultraviolet to the infrared is analyzed; the strongly correlated (SC) states arising in the infrared are investigated. Experimental consequences of the physics are presented -- the SC states arising at various fillings are shown to be drastically different, with distinct signatures in the conductance and, in particular, the noise. Besides CNT QDs, our results are also relevant to double QD systems.Comment: 5 pages, 5 figure

Social Participation in Relation to Technology Use and Social Deprivation: A Mixed Methods Study Among Older People with and without Dementia

Social participation is a modifiable determinant for health and wellbeing among older people; however, social participation is increasingly dependent on technology use. This study investigated social participation in relation to Everyday Technology use and social deprivation of the living environment, among older people with and without dementia in the United Kingdom. Sixty-four people with dementia and sixty-four people without dementia were interviewed using standardized questionnaires: The Participation in ACTivities and Places OUTside Home Questionnaire and Everyday Technology Use Questionnaire. A mixed methods approach integrated statistical analyses and content analysis of free-text responses, through data visualizations. Small, statistically significant associations were found between social participation and Everyday Technology use outside home, for participants with dementia (Rs = 0.247; p = 0.049) and without dementia (Rs = 0.343; p = 0.006). A small, statistically significant association was identified between social participation and social deprivation in the living environment, among only participants with dementia (Rs = 0.267, p = 0.033). The content analysis and graphical joint display revealed motivators, considerations that require extra attention, and strategies for managing social participation. The results underline how Everyday Technology use can be assistive to social participation but also the need to consider social deprivation of the living environment, especially among people with dementia

Structural properties of hard disks in a narrow tube

Positional ordering of a two-dimensional fluid of hard disks is examined in such narrow tubes where only the nearest-neighbor interactions take place. Using the exact transfer-matrix method the transverse and longitudinal pressure components and the correlation function are determined numerically. Fluid-solid phase transition does not occur even in the widest tube, where the method just loses its exactness, but the appearance of the dramatic change in the equation of state and the longitudinal correlation function shows that the system undergoes a structural change from a fluid to a solid-like order. The pressure components show that the collisions are dominantly longitudinal at low densities, while they are transverse in the vicinity of close packing density. The transverse correlation function shows that the size of solid-like domains grows exponentially with increasing pressure and the correlation length diverges at close packing. It is managed to find an analytically solvable model by expanding the contact distance up to first order. The approximate model, which corresponds to the system of hard parallel rhombuses, behaves very similarly to the system of hard disks.Comment: Acceped in Journal of Statistical Mechanics: Theory and Experimen

Living with early-stage dementia: a review of qualitative studies

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Compression of multi-year meteorological data

Dynamic simulation programes require hourly values of solar radiation and ambient temperature forming large files, which are usually difficult to handle with available personal computers (PC). This report describes stochastic models of these variables which have been constructed to overcome this difficulty. They are based on Markov chains and autoregressive processes, determined using multi-year hourly data of both variables. A validation of the model has been carried out for five different Swiss locations. It has shown that the main statistical characteristics of these variables are reproduced by the models. A very good agreement was also obtained between results of dynamic simulations carried out using measured and synthetic data. The generalization of the method to 30 Swiss locations has been made to facilitate the transfer of these developments into practice

A large community outbreak of waterborne giardiasis- delayed detection in a non-endemic urban area

BACKGROUND: Giardia is not endemic in Norway, and more than 90% of reported cases acquire the infection abroad. In late October 2004, an increase in laboratory confirmed cases of giardiasis was reported in the city of Bergen. An investigation was started to determine the source and extent of the outbreak in order to implement control measures. METHODS: Cases were identified through the laboratory conducting giardia diagnostics in the area. All laboratory-confirmed cases were mapped based on address of residence, and attack rates and relative risks were calculated for each water supply zone. A case control study was conducted among people living in the central area of Bergen using age- and sex matched controls randomly selected from the population register. RESULTS: The outbreak investigation showed that the outbreak started in late August and peaked in early October. A total of 1300 laboratory-confirmed cases were reported. Data from the Norwegian Prescription Database gave an estimate of 2500 cases treated for giardiasis probably linked to the outbreak. There was a predominance of women aged 20–29 years, with few children or elderly. The risk of infection for persons receiving water from the water supply serving Bergen city centre was significantly higher than for those receiving water from other supplies. Leaking sewage pipes combined with insufficient water treatment was the likely cause of the outbreak. CONCLUSION: Late detection contributed to the large public health impact of this outbreak. Passive surveillance of laboratory-confirmed cases is not sufficient for timely detection of outbreaks with non-endemic infections

Interference effects in electronic transport through metallic single-wall carbon nanotubes

In a recent paper Liang {\it et al.} [Nature {\bf 411}, 665 (2001)] showed experimentally, that metallic nanotubes, strongly coupled to external electrodes, may act as coherent molecular waveguides for electronic transport. The experimental results were supported by theoretical analysis based on the scattering matrix approach. In this paper we analyze theoretically this problem using a real-space approach, which makes it possible to control quality of interface contacts. Electronic structure of the nanotube is taken into account within the tight-binding model. External electrodes and the central part (sample) are assumed to be made of carbon nanotubes, while the contacts between electrodes and the sample are modeled by appropriate on-site (diagonal) and hopping (off-diagonal) parameters. Conductance is calculated by the Green function technique combined with the Landauer formalism. In the plots displaying conductance {\it vs.} bias and gate voltages, we have found typical diamond structure patterns, similar to those observed experimentally. In certain cases, however, we have found new features in the patterns, like a double-diamond sub-structure.Comment: 15 pages, 4 figures. To apear in Phys. Rev.