Device for handling heavy loads

Device for handling heavy loads by distributing force

Uniform Density Theorem for the Hubbard Model

A general class of hopping models on a finite bipartite lattice is considered, including the Hubbard model and the Falicov-Kimball model. For the half-filled band, the single-particle density matrix \uprho (x,y) in the ground state and in the canonical and grand canonical ensembles is shown to be constant on the diagonal $x=y$, and to vanish if $x \not=y$ and if $x$ and $y$ are on the same sublattice. For free electron hopping models, it is shown in addition that there are no correlations between sites of the same sublattice in any higher order density matrix. Physical implications are discussed.Comment: 15 pages, plaintex, EHLMLRJM-22/Feb/9

Measurement of the energy dependence of phase relaxation by single electron tunneling

Single electron tunneling through a single impurity level is used to probe the fluctuations of the local density of states in the emitter. The energy dependence of quasi-particle relaxation in the emitter can be extracted from the damping of the fluctuations of the local density of states (LDOS). At larger magnetic fields Zeeman splitting is observed.Comment: 2 pages, 4 figures; 25th International Conference on the Physics of Semiconductors, Osaka, Japan, September 17-22, 200

Universality in escape from a modulated potential well

We show that the rate of activated escape $W$ from a periodically modulated potential displays scaling behavior versus modulation amplitude $A$. For adiabatic modulation of an optically trapped Brownian particle, measurements yield $\ln W\propto (A_{\rm c} - A)^{\mu}$ with $\mu = 1.5$. The theory gives $\mu=3/2$ in the adiabatic limit and predicts a crossover to $\mu=2$ scaling as $A$ approaches the bifurcation point where the metastable state disappears.Comment: 4 pages, 3 figure

Tunable graphene system with two decoupled monolayers

The use of two truly two-dimensional gapless semiconductors, monolayer and bilayer graphene, as current-carrying components in field-effect transistors (FET) gives access to new types of nanoelectronic devices. Here, we report on the development of graphene-based FETs containing two decoupled graphene monolayers manufactured from a single one folded during the exfoliation process. The transport characteristics of these newly-developed devices differ markedly from those manufactured from a single-crystal bilayer. By analyzing Shubnikov-de Haas oscillations, we demonstrate the possibility to independently control the carrier densities in both layers using top and bottom gates, despite there being only a nanometer scale separation between them

The regional and sectoral mobility of high-tech workers:insights from Finland

In this paper we employ data on 156,000 workers working within the Finnish high-tech industries in order to identify the extent to which labour mobility between sectors and regions is influenced by the characteristics of the locality in which the worker works. With these data we are able to estimate different types of binary, multinomial and ordered logit models to capture different types of inter- or intra-sector or region employment mobility. As we will see the different categories of employment mobility are influenced by different factors such that we cannot simply talk about 'labour mobility', but rather need to be specific regarding each particular form of employment mobility. Our results show that urbanisation and industrial diversity are not just associated with greater intra-regional mobility, as is emphasised by the agglomeration literature, but also greater inter-regional mobility