343 research outputs found
Living in Living Cities
This paper presents an overview of current and potential applications of
living technology to some urban problems. Living technology can be described as
technology that exhibits the core features of living systems. These features
can be useful to solve dynamic problems. In particular, urban problems
concerning mobility, logistics, telecommunications, governance, safety,
sustainability, and society and culture are presented, while solutions
involving living technology are reviewed. A methodology for developing living
technology is mentioned, while supraoptimal public transportation systems are
used as a case study to illustrate the benefits of urban living technology.
Finally, the usefulness of describing cities as living systems is discussed.Comment: 40 pages, 4 figures, overview pape
Mesoscopic, Non-equilibrium Fluctuations of Inhomogeneous Electronic States in Manganites
By using the dark-field real-space imaging technique of transmission electron
microscopy (TEM), we have observed slow 200 A-scale fluctuations of
charge-ordered (CO) phase in mixed-valent manganites under a strong electron
beam irradiation. In addition to these unusual fluctuations of the CO phase, we
observed the switching-type fluctuations of electrical resistivity in the same
sample, which were found to be as large as several percents. Systematic
analysis indicates that these two different types of fluctuations with a
similar time scale of the order of seconds are interconnected through a
meta-stable insulating charge-disordered state. Current dependence of the
fluctuations suggests a non-equilibrium nature of this slow dynamics.Comment: To appear in Europhysics Letter
Self-aligned nanoscale SQUID on a tip
A nanometer-sized superconducting quantum interference device (nanoSQUID) is
fabricated on the apex of a sharp quartz tip and integrated into a scanning
SQUID microscope. A simple self-aligned fabrication method results in
nanoSQUIDs with diameters down to 100 nm with no lithographic processing. An
aluminum nanoSQUID with an effective area of 0.034 m displays flux
sensitivity of 1.8 \mu_B/\mathrm{Hz}^{1/2}$ and high bandwidth, the SQUID on a tip is a highly
promising probe for nanoscale magnetic imaging and spectroscopy.Comment: 14 manuscript pages, 5 figure
From cellular attractor selection to adaptive signal control for traffic networks
The management of varying traffic flows essentially depends on signal controls at intersections. However, design an optimal control that considers the dynamic nature of a traffic network and coordinates all intersections simultaneously in a centralized manner is computationally challenging. Inspired by the stable gene expressions of Escherichia coli in response to environmental changes, we explore the robustness and adaptability performance of signalized intersections by incorporating a biological mechanism in their control policies, specifically, the evolution of each intersection is induced by the dynamics governing an adaptive attractor selection in cells. We employ a mathematical model to capture such biological attractor selection and derive a generic, adaptive and distributed control algorithm which is capable of dynamically adapting signal operations for the entire dynamical traffic network. We show that the proposed scheme based on attractor selection can not only promote the balance of traffic loads on each link of the network but also allows the global network to accommodate dynamical traffic demands. Our work demonstrates the potential of bio-inspired intelligence emerging from cells and provides a deep understanding of adaptive attractor selection-based control formation that is useful to support the designs of adaptive optimization and control in other domains
Spatially organizing future genders: an artistic intervention in the creation of a hir-toilet
Toilets, a neglected facility in the study of human relations at work and beyond, have become increasingly important in discussions about future experiences of gender diversity. To further investigate the spatial production of gender and its potential expressions, we transformed a unisex single-occupancy toilet at Uppsala University into an all-gender or ‘hir-toilet’.1 With the aim to disrupt and expose the dominant spatial organization of the two binary genders, we inaugurated the hir-toilet with the help of a performance artist. We describe and analyse internal and external responses thereto, using Lefebvre’s work on dialectics and space. Focusing on how space is variously lived, conceived and perceived, our analysis questions the very rationale of gender categorizations. The results contribute to a renewed critique of binary thinking in the organization of workplaces by extending our understanding of how space and human relations mutually constitute each other
Electronic Transport in a Three-dimensional Network of 1-D Bismuth Quantum Wires
The resistance R of a high density network of 6 nm diameter Bi wires in
porous Vycor glass is studied in order to observe its expected semiconductor
behavior. R increases from 300 K down to 0.3 K. Below 4 K, where R varies
approximately as ln(1/T), the order-of-magnitude of the resistance rise, as
well as the behavior of the magnetoresistance are consistent with localization
and electron-electron interaction theories of a one-dimensional disordered
conductor in the presence of strong spin-orbit scattering. We show that this
behaviour and the surface-enhanced carrier density may mask the proposed
semimetal-to-semiconductor transition for quantum Bi wires.Comment: 19 pages total, 4 figures; accepted for publication in Phys. Rev.
Interaction effects and phase relaxation in disordered systems
This paper is intended to demonstrate that there is no need to revise the
existing theory of the transport properties of disordered conductors in the
so-called weak localization regime. In particular, we demonstrate explicitly
that recent attempts to justify theoretically that the dephasing rate
(extracted from the magnetoresistance) remains finite at zero temperature are
based on the profoundly incorrect calculation. This demonstration is based on a
straightforward evaluation of the effect of the electron-electron interaction
on the weak localization correction to the conductivity of disordered metals.
Using well-controlled perturbation theory with the inverse conductance as
the small parameter, we show that this effect consists of two contributions.
First contribution comes from the processes with energy transfer smaller than
the temperature. This contribution is responsible for setting the energy scale
for the magnetoresistance. The second contribution originates from the virtual
processes with energy transfer larger than the temperature. It is shown that
the latter processes have nothing to do with the dephasing, but rather manifest
the second order (in ) correction to the conductance. This correction is
calculated for the first time. The paper also contains a brief review of the
existing experiments on the dephasing of electrons in disordered conductors and
an extended qualitative discussion of the quantum corrections to the
conductivity and to the density of electronic states in the weak localization
regime.Comment: 34 pages, 13 .eps figure
Multidisciplinary applications of complex networks modeling, simulation, visualization, and analysis
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