22,204 research outputs found
Transport in a sustainable urban future
Transport is acknowledged as a vital ingredient of any credible strategy for the sustainable city because of the key role it plays in promoting economic development, quality of life and wellbeing. Yet managing urban transport effectively, given its complex and intersecting economic, environmental and social impacts, is also precisely the kind of âwicked problemâ that policy makers consistently find hard to resolve (Docherty and Shaw, 2011a; Conklin, 2006; Rittel and Webber, 1973). Many of the reasons for this are longstanding and emanate in particular from the dominance of the private car in meeting the demand for mobility, which has built up over many decades in the developed world, but which is now being reproduced at a much higher pace in the fast growing cities of the Pacific Rim and elsewhere (Newman and Kenworthy, 1999; Lyons and Loo, 2008). Although it has undoubtedly transformed our patterns of travel and consumption, concerns over the limitations and externalities of private car transport â primarily traffic congestion, environmental degradation and social exclusion â have for many years stimulated various initiatives designed to mitigate these externalities (Feitelson and Verhoef, 2001; Knowles et al, 2008). The conflict between the car, long promoted by neoliberal voices as a potent weapon of the free market and individual liberty, and competing visions of a more âpublicâ transport system based on collective modes such as the bus and train, and active travel by walking and cycling, has been played out over many years. Nowhere has this conflict been more intense than in cities, as it is here that the problems such as congestion, poor local air quality and mobility deprivation are often at their most intense (Cahill, 2010; Docherty et al, 2008)
Devolution as process: institutional structures, state personnel and transport policy in the United Kingdom
Devolution has been described as a key âglobal trendâ over recent decades as governments have decentralised power and responsibilities to subordinate regional institutions (Rodriguez-Pose and Gill, 2003). UK devolution is characterised by its asymmetrical nature with different territories granted different institutional arrangements and powers. In this paper, we seek examine the role of state personnel in mobilising the new institutional machinery and managing the process of devolution, focusing on transport policy. Our research shows a clear contrast between London and Northern Ireland, on the one hand, and Scotland and Wales, on the other, in terms of the effectiveness of political leaders in creating clear policy priorities and momentum in transport
Transport strategy in Scotland since devolution
This article critically reviews how the Scottish Executive's approach to transport has developed since devolution. Although there is much to commend, a number of concerns can be identified, including the possibility that a number of strategic infrastructure schemes appear to have been approved on political rather than on technical grounds. It is difficult to know whether the current set of transport infrastructure investment plans represents good value for public money
Activation of the P2Y2 receptor regulates bone cell function by enhancing ATP release
Bone cells constitutively release ATP into the extracellular environment where it acts locally via P2 receptors to regulate bone cell function. Whilst P2Y2 receptor stimulation regulates bone mineralisation, the functional effects of this receptor in osteoclasts remain unknown. This investigation used the P2Y2 receptor knockout (P2Y2Râ/â) mouse model to investigate the role of this receptor in bone. MicroCT analysis of P2Y2Râ/â mice demonstrated age-related increases in trabecular bone volume (â€48%), number (â€30%) and thickness (â€17%). In vitro P2Y2Râ/â osteoblasts displayed a 3-fold increase in bone formation and alkaline phosphatase activity, whilst P2Y2Râ/â osteoclasts exhibited a 65% reduction in resorptive activity. Serum cross-linked C-telopeptide levels (CTX, resorption marker) were also decreased (â€35%). The resorption defect in P2Y2Râ/â osteoclasts was rescued by the addition of exogenous ATP, suggesting that an ATP deficit could be a key factor in the reduced function of these cells. In agreement, we found that basal ATP release was reduced up to 53% in P2Y2Râ/â osteoclasts. The P2Y2 receptor agonists, UTP and 2-thioUTP, increased osteoclast activity and ATP release in wild-type but not in P2Y2Râ/â cells. This indicates that the P2Y2 receptor may regulate osteoclast function indirectly by promoting ATP release. UTP and 2-thioUTP also stimulate ATP release from osteoblasts suggesting that the P2Y2 receptor exerts a similar function in these cells. Taken together, our findings are consistent with the notion that the primary action of P2Y2 receptor signalling in bone is to regulate extracellular ATP levels
Events leading up to the June 2015 outburst of V404 Cyg
On 2015 June 15 the burst alert telescope (BAT) on board {\em Swift} detected
an X-ray outburst from the black hole transient V404 Cyg. We monitored V404 Cyg
for the last 10 years with the 2-m Faulkes Telescope North in three optical
bands (V, R, and i). We found that, one week prior to this outburst, the
optical flux was 0.1--0.3 mag brighter than the quiescent orbital modulation,
implying an optical precursor to the X-ray outburst. There is also a hint of a
gradual optical decay (years) followed by a rise lasting two months prior to
the outburst. We fortuitously obtained an optical spectrum of V404 Cyg 13 hours
before the BAT trigger. This too was brighter () than
quiescence, and showed spectral lines typical of an accretion disk, with
characteristic absorption features of the donor being much weaker. No He II
emission was detected, which would have been expected had the X-ray flux been
substantially brightening. This, combined with the presence of intense
H emission, about 7 times the quiescent level, suggests that the disk
entered the hot, outburst state before the X-ray outburst began. We propose
that the outburst is produced by a viscous-thermal instability triggered close
to the inner edge of a truncated disk. An X-ray delay of a week is consistent
with the time needed to refill the inner region and hence move the inner edge
of the disk inwards, allowing matter to reach the central BH, finally turning
on the X-ray emission.Comment: Accepted by ApJ Letter, 7 pages, 5 figure
National evaluation of the neighbourhood nurseries: impact report
This study assessed the impact of NNI on parental employment, use of formal childcare, and take-up of benefits and tax credits, particularly for disadvantaged groups such as lone parents, low income families and ethnic minority groups
Spectrum of an oscillator with jumping frequency and the interference of partial susceptibilities
We study an underdamped oscillator with shot-noise frequency fluctuations.
The oscillator spectrum is determined by the interference of the
susceptibilities for different eigenfrequencies. Depending on the parameters,
it has a fine structure or displays a single asymmetric peak. For
nano-mechanical resonators with a fluctuating number of attached molecules, the
spectrum is found in a simple analytical form. The results bear on various
types of systems where the reciprocal correlation time of frequency
fluctuations can be comparable to the typical frequency jumps
Characterization of a Differential Radio-Frequency Single-Electron Transistor
We have fabricated and characterized a new type of electrometer that couples
two parallel single-electron transistors (SETs) to a radio-frequency tank
circuit for use as a differential RF-SET. We demonstrate operation of this
device in summing, differential, and single-SET operation modes, and use it to
measure a Coulomb staircase from a differential single Cooper-pair box. In
differential mode, the device is sensitive to uncorrelated input signals while
screening out correlated ones.Comment: 3 pages, 3 figures, submitted to Applied Physics Letter
The validity of 21 cm spin temperature as a kinetic temperature indicator in atomic and molecular gas
The gas kinetic temperature () of various interstellar environments is
often inferred from observations that can deduce level populations of atoms,
ions, or molecules using spectral line observations; H I 21 cm is perhaps the
most widely used with a long history. Usually the H I 21 cm line is assumed to
be in thermal equilibrium and the populations are given by the Boltzmann
distribution. A variety of processes, many involving Lyman alpha (),
can affect the 21 cm line. Here we show how this is treated in the spectral
simulation code Cloudy, and present numerical simulations of environments where
this temperature indicator is used, with a detailed treatment of the physical
processes that determine level populations within . We discuss situations
where this temperature indicator traces , cases where they fail, as well
as the effects of pumping on the 21 cm spin temperature. We also
show that the excitation temperature rarely traces the gas kinetic
temperature.Comment: Accepted for publication in Ap
The Validity of 21 cm Spin Temperature as a Kinetic Temperature Indicator in Atomic and Molecular Gas
The gas kinetic temperature (TK) of various interstellar environments is often inferred from observations that can deduce level populations of atoms, ions, or molecules using spectral line observations; H I 21 cm is perhaps the most widely used, and has a long history. Usually the H I 21 cm line is assumed to be in thermal equilibrium and the populations are given by the Boltzmann distribution. A variety of processes, many involving Lyα, can affect the 21 cm line. Here we show how this is treated in the spectral simulation code Cloudy, and present numerical simulations of environments where this temperature indicator is used, with a detailed treatment of the physical processes that determine level populations within H0. We discuss situations where this temperature indicator traces TK, cases where it fails, as well as the effects of Lyα pumping on the 21 cm spin temperature. We also show that the Lyα excitation temperature rarely traces the gas kinetic temperature
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