113 research outputs found
Review of UK microgeneration. Part 1 : policy and behavioural aspects
A critical review of the literature relating to government policy and behavioural aspects relevant to the uptake and application of microgeneration in the UK is presented. Given the current policy context aspiring to zero-carbon new homes by 2016 and a variety of minimum standards and financial policy instruments supporting microgeneration in existing dwellings, it appears that this class of technologies could make a significant contribution to UK energy supply and low-carbon buildings in the future. Indeed, achievement of a reduction in greenhouse gas emissions by 80% (the UK government's 2050 target) for the residential sector may entail substantial deployment of microgeneration. Realisation of the large potential market for microgeneration relies on a variety of inter-related factors such as microeconomics, behavioural aspects, the structure of supporting policy instruments and well-informed technology development. This article explores these issues in terms of current and proposed policy instruments in the UK. Behavioural aspects associated with both initial uptake of the technology and after purchase are also considered
Interpreting complex fluvial channel and barform architecture: Carboniferous Central Pennine Province, northern England
The Bashkirian Lower Brimham Grit of North Yorkshire, England, is a fluvio-deltaic sandstone succession that crops out as a complex series of pinnacles, the three-dimensional arrangement of which allows high-resolution architectural analysis of genetically-related lithofacies assemblages. Combined analysis of sedimentary graphic log profiles, architectural panels and palaeocurrent data have enabled three-dimensional geometrical relationships to be established for a suite of architectural elements so as to develop a comprehensive depositional model. Small-scale observations of facies have been related to larger-scale architectural elements to facilitate interpretation of the palaeoenvironment of deposition to a level of detail that has rarely been attempted previously, thereby allowing interpretation of formative processes. Detailed architectural panels form the basis of a semi-quantitative technique for recording the variety and complexity of the sedimentary lithofacies present, their association within recognizable architectural elements and, thus, the inferred spatio-temporal relationship of neighbouring elements. Fluvial channel-fill elements bounded by erosional surfaces are characterized internally by a hierarchy of sets and cosets with subtly varying compositions, textures and structures. Simple, cross-bedded sets represent in-channel migration of isolated mesoforms (dunes); cosets of both trough and planar-tabular cross-bedded facies represent lateral-accreting and downstream-accreting macroforms (bars) characterized by highly variable, yet predictable, patterns of palaeocurrent indicators. Relationships between sandstone-dominated strata bounded by third-order and fifth-order surfaces, which represent in-channel bar deposits and incised channel bases respectively, chronicle the origin of the preserved succession in response to autocyclic barform development and abandonment, major episodes of incision probably influenced by episodic tectonic subsidence, differential tilting and fluvial incision associated with slip on the nearby North Craven Fault system. Overall, the succession represents the preserved product of an upper-delta plain system that was traversed by a migratory fluvial braid-belt system comprising a poorly-confined network of fluvial channels developed between major sandy barforms that evolved via combined lateral-accretion and downstream-accretion
Cosmological Consequences of String-forming Open Inflation Models
We present a study of open inflation cosmological scenarios in which cosmic
strings form betwen the two inflationary epochs. It is shown that in these
models strings are stretched outside the horizon due to the inflationary
expansion but must necessarily re-enter the horizon before the epoch of equal
matter and radiation densities. We determine the power spectrum of cold dark
matter perturbations in these hybrid models, finding good agreement with
observations for values of and comparable
contributions from the active and passive sources to the CMB. Finally, we
briefly discuss other cosmological consequences of these models.Comment: 11 LaTeX pages with 3 eps figure
Current cosmological bounds on neutrino masses and relativistic relics
We combine the most recent observations of large-scale structure (2dF and
SDSS galaxy surveys) and cosmic microwave anisotropies (WMAP and ACBAR) to put
constraints on flat cosmological models where the number of massive neutrinos
and of massless relativistic relics are both left arbitrary. We discuss the
impact of each dataset and of various priors on our bounds. For the standard
case of three thermalized neutrinos, we find an upper bound on the total
neutrino mass sum m_nu < 1.0 (resp. 0.6) eV (at 2sigma), using only CMB and LSS
data (resp. including priors from supernovae data and the HST Key Project), a
bound that is quite insensitive to the splitting of the total mass between the
three species. When the total number of neutrinos or relativistic relics N_eff
is left free, the upper bound on sum m_nu (at 2sigma, including all priors)
ranges from 1.0 to 1.5 eV depending on the mass splitting. We provide an
explanation of the parameter degeneracy that allows larger values of the masses
when N_eff increases. Finally, we show that the limit on the total neutrino
mass is not significantly modified in the presence of primordial gravitational
waves, because current data provide a clear distinction between the
corresponding effects.Comment: 13 pages, 6 figure
Limits on the gravity wave contribution to microwave anisotropies
We present limits on the fraction of large angle microwave anisotropies which
could come from tensor perturbations. We use the COBE results as well as
smaller scale CMB observations, measurements of galaxy correlations, abundances
of galaxy clusters, and Lyman alpha absorption cloud statistics. Our aim is to
provide conservative limits on the tensor-to-scalar ratio for standard
inflationary models. For power-law inflation, for example, we find T/S<0.52 at
95% confidence, with a similar constraint for phi^p potentials. However, for
models with tensor amplitude unrelated to the scalar spectral index it is still
currently possible to have T/S>1.Comment: 23 pages, 7 figures, accepted for publication in Phys. Rev. D.
Calculations extended to blue spectral index, Fig. 6 added, discussion of
results expande
Out of equilibrium: understanding cosmological evolution to lower-entropy states
Despite the importance of the Second Law of Thermodynamics, it is not
absolute. Statistical mechanics implies that, given sufficient time, systems
near equilibrium will spontaneously fluctuate into lower-entropy states,
locally reversing the thermodynamic arrow of time. We study the time
development of such fluctuations, especially the very large fluctuations
relevant to cosmology. Under fairly general assumptions, the most likely
history of a fluctuation out of equilibrium is simply the CPT conjugate of the
most likely way a system relaxes back to equilibrium. We use this idea to
elucidate the spacetime structure of various fluctuations in (stable and
metastable) de Sitter space and thermal anti-de Sitter space.Comment: 27 pages, 11 figure
Hadronic Axion Model in Gauge-Mediated Supersymmetry Breaking and Cosmology of Saxion
Recently we have proposed a simple hadronic axion model within gauge-mediated
supersymmetry breaking. In this paper we discuss various cosmological
consequences of the model in great detail. A particular attention is paid to a
saxion, a scalar partner of an axion, which is produced as a coherent
oscillation in the early universe. We show that our model is cosmologically
viable, if the reheating temperature of inflation is sufficiently low. We also
discuss the late decay of the saxion which gives a preferable power spectrum of
the density fluctuation in the standard cold dark matter model when compared
with the observation.Comment: 24 pages, 3 figure
Constraining the expansion rate of the Universe using low-redshift ellipticals as cosmic chronometers
We present a new methodology to determine the expansion history of the
Universe analyzing the spectral properties of early type galaxies (ETG). We
found that for these galaxies the 4000\AA break is a spectral feature that
correlates with the relative ages of ETGs. In this paper we describe the
method, explore its robustness using theoretical synthetic stellar population
models, and apply it using a SDSS sample of 14 000 ETGs. Our motivation
to look for a new technique has been to minimise the dependence of the cosmic
chronometer method on systematic errors. In particular, as a test of our
method, we derive the value of the Hubble constant (stat)
(syst) (68% confidence), which is not only fully compatible with the
value derived from the Hubble key project, but also with a comparable error
budget. Using the SDSS, we also derive, assuming w=constant, a value for the
dark energy equation of state parameter (stat)
(syst). Given the fact that the SDSS ETG sample only reaches , this
result shows the potential of the method. In future papers we will present
results using the high-redshift universe, to yield a determination of H(z) up
to .Comment: 25 pages, 17 figures, JCAP accepte
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