1,127 research outputs found
Managing urban socio-technical change? Comparing energy technology controversies in three European contexts
A {\em local graph partitioning algorithm} finds a set of vertices with small
conductance (i.e. a sparse cut) by adaptively exploring part of a large graph
, starting from a specified vertex. For the algorithm to be local, its
complexity must be bounded in terms of the size of the set that it outputs,
with at most a weak dependence on the number of vertices in . Previous
local partitioning algorithms find sparse cuts using random walks and
personalized PageRank. In this paper, we introduce a randomized local
partitioning algorithm that finds a sparse cut by simulating the {\em
volume-biased evolving set process}, which is a Markov chain on sets of
vertices. We prove that for any set of vertices that has conductance at
most , for at least half of the starting vertices in our algorithm
will output (with probability at least half), a set of conductance
. We prove that for a given run of the algorithm,
the expected ratio between its computational complexity and the volume of the
set that it outputs is . In comparison, the best
previous local partitioning algorithm, due to Andersen, Chung, and Lang, has
the same approximation guarantee, but a larger ratio of between the complexity and output volume. Using our local
partitioning algorithm as a subroutine, we construct a fast algorithm for
finding balanced cuts. Given a fixed value of , the resulting algorithm
has complexity and returns a cut with
conductance and volume at least ,
where is the largest volume of any set with conductance at most
.Comment: 20 pages, no figure
Finnish Energy Policy in Transition
This open access book examines the role of citizens in sustainable energy transitions across Europe. It explores energy problem framing, policy approaches and practical responses to the challenge of securing clean, affordable and sustainable energy for all citizens, focusing on households as the main unit of analysis. The book revolves around ten contributions that each summarise national trends, socio-material characteristics, and policy responses to contemporary energy issues affecting householders in different countries, and provides good practice examples for designing and implementing sustainable energy initiatives. Prominent concerns include reducing carbon emissions, energy poverty, sustainable consumption, governance, practices, innovations and sustainable lifestyles. The opening and closing contributions consider European level energy policy, dominant and alternative problem framings and similarities and differences between European countries in relation to reducing household energy use. Overall, the book is a valuable resource for researchers, policy-makers, practitioners and others interested in sustainable energy perspectives. In Finland, energy policy is in transition towards integrating energy projects in broader sustainability, liveability and innovation contexts. While energy saving has been pursued for decades, it is now part of a broader tendency in urban planning to promote sustainable lifestyles. Transition manifests in local actors’ redistribution of power, challenging conventional ways of infrastructure development, forging new networks, and seeking novel solutions. The experimental case presented in the chapter, Smart Kalasatama, shows that local governments are close to citizens and, therefore, can infuence the conditions for sustainable consumption and quality of life. Although they have an important role in energy policy, they still might lack the resources, expertise and the power to innovate, to evaluate projects, and in particular, to scale up innovative practices.Non peer reviewe
Developing LCA-based benchmarks for sustainable consumption - for and with users
This article presents the development process of a consumer-oriented, illustrative benchmarking tool enabling consumers to use the results of environmental life cycle assessment (LCA) to make informed decisions. Active and environmentally conscious consumers and environmental communicators were identified as key target groups for this type of information. A brochure presenting the benchmarking tool was developed as an participatory, iterative process involving consumer focus groups, stakeholder workshops and questionnaire-based feedback. In addition to learning what works and what does not, detailed suggestions on improved wording and figures were obtained, as well as a wealth of ideas for future applications
Edge-dependent selection rules in magic triangular graphene flakes
The electronic shell and supershell structure of triangular graphene quantum
dots has been studied using density functional and tight-binding methods. The
density functional calculations demonstrate that the electronic structure close
to the Fermi energy is correctly described with a simple tight-binding model
where only the p_z orbitals perpendicular to the graphene layer are included.
The results show that (i) both at the bottom and at the top of the p_z band a
supershell structure similar to that of free electrons confined in a triangular
cavity is seen, (ii) close to the Fermi level the shell structure is that of
free massless particles, (iii) triangles with armchair edges show an additional
sequence of levels ('ghost states') absent for triangles with zigzag edges
while the latter exhibit edge states, and (iv) the observed shell structure is
rather insensitive to the edge roughness
PRELI is a mitochondrial regulator of human primary T-helper cell apoptosis, STAT6, and Th2-cell differentiation
The identification of novel factors regulating human T helper (Th)–cell differentiation into
functionally distinct Th1 and Th2 subsets is important for understanding the mechanisms behind human autoimmune
and allergic diseases. We have identified a protein of relevant evolutionary and lymphoid interest (PRELI), a
novel protein that induces oxidative stress and a mitochondrial apoptosis pathway in human primary Th cells. We
also demonstrated that PRELI inhibits Th2-cell development and down-regulates signal transducer and activator of
transcription 6 (STAT6), a key transcription factor driving Th2 differentiation. Our data suggest that calpain, an
oxidative stress–induced cysteine protease, is involved in the PRELI-induced down-regulation of STAT6. Moreover,
we observed that a strong T-cell receptor (TCR) stimulus induces expression of PRELI and inhibits Th2 development.
Our results suggest that PRELI is involved in a mechanism wherein the strength of the TCR stimulus influences the
polarization of Th cells. This study identifies PRELI as a novel factor influencing the human primary Th-cell
death and differentiation
Electronic structure of triangular, hexagonal and round graphene flakes near the Fermi level
The electronic shell structure of triangular, hexagonal and round graphene
quantum dots (flakes) near the Fermi level has been studied using a
tight-binding method. The results show that close to the Fermi level the shell
structure of a triangular flake is that of free massless particles, and that
triangles with an armchair edge show an additional sequence of levels ("ghost
states"). These levels result from the graphene band structure and the plane
wave solution of the wave equation, and they are absent for triangles with an
zigzag edge. All zigzag triangles exhibit a prominent edge state at the Fermi
level, and few low-energy conduction electron states occur both in triangular
and hexagonal flakes due to symmetry reasons. Armchair triangles can be used as
building blocks for other types of flakes that support the ghost states. Edge
roughness has only a small effect on the level structure of the triangular
flakes, but the effect is considerably enhanced in the other types of flakes.
In round flakes, the states near the Fermi level depend strongly on the flake
radius, and they are always localized on the zigzag parts of the edge
Sleep-wake sensitive mechanisms of adenosine release in the basal forebrain of rodents : an in vitro study
Adenosine acting in the basal forebrain is a key mediator of sleep homeostasis. Extracellular adenosine concentrations increase during wakefulness, especially during prolonged wakefulness and lead to increased sleep pressure and subsequent rebound sleep. The release of endogenous adenosine during the sleep-wake cycle has mainly been studied in vivo with microdialysis techniques. The biochemical changes that accompany sleep-wake status may be preserved in vitro. We have therefore used adenosine-sensitive biosensors in slices of the basal forebrain (BFB) to study both depolarization-evoked adenosine release and the steady state adenosine tone in rats, mice and hamsters. Adenosine release was evoked by high K+, AMPA, NMDA and mGlu receptor agonists, but not by other transmitters associated with wakefulness such as orexin, histamine or neurotensin. Evoked and basal adenosine release in the BFB in vitro exhibited three key features: the magnitude of each varied systematically with the diurnal time at which the animal was sacrificed; sleep deprivation prior to sacrifice greatly increased both evoked adenosine release and the basal tone; and the enhancement of evoked adenosine release and basal tone resulting from sleep deprivation was reversed by the inducible nitric oxide synthase (iNOS) inhibitor, 1400 W. These data indicate that characteristics of adenosine release recorded in the BFB in vitro reflect those that have been linked in vivo to the homeostatic control of sleep. Our results provide methodologically independent support for a key role for induction of iNOS as a trigger for enhanced adenosine release following sleep deprivation and suggest that this induction may constitute a biochemical memory of this state
Rectangular quantum dots in high magnetic fields
We use density-functional methods to study the effects of an external
magnetic field on two-dimensional quantum dots with a rectangular hard-wall
confining potential. The increasing magnetic field leads to spin polarization
and formation of a highly inhomogeneous maximum-density droplet at the
predicted magnetic field strength. At higher fields, we find an oscillating
behavior in the electron density and in the magnetization of the dot. We
identify a rich variety of phenomena behind the periodicity and analyze the
complicated many-electron dynamics, which is shown to be highly dependent on
the shape of the quantum dot.Comment: 6 pages, 6 figures, submitted to Phys. Rev.
Electronic structure of rectangular quantum dots
We study the ground state properties of rectangular quantum dots by using the
spin-density-functional theory and quantum Monte Carlo methods. The dot
geometry is determined by an infinite hard-wall potential to enable comparison
to manufactured, rectangular-shaped quantum dots. We show that the electronic
structure is very sensitive to the deformation, and at realistic sizes the
non-interacting picture determines the general behavior. However, close to the
degenerate points where Hund's rule applies, we find spin-density-wave-like
solutions bracketing the partially polarized states. In the
quasi-one-dimensional limit we find permanent charge-density waves, and at a
sufficiently large deformation or low density, there are strongly localized
stable states with a broken spin-symmetry.Comment: 8 pages, 9 figures, submitted to PR
- …