6,481 research outputs found
The carbon-saving behaviour of residential households
The housing sector in 2004 was accountable for about 30% of total UK carbon emissions. The magnitude of this figure represents a significant imperative for policymakers to act on the sector through behavioural change strategies. Energy efficiency in households might easily be considered as driven mainly by economic motives, but this would not explain why even cost-free behavioural changes, like switching the lights off more often, are not adopted more widely. Literature has mainly concentrated either on the economic motives of pro-environmental behaviours or on the relevance of attitudes to shape them. Little has been said so far on the interaction between attitudes and the so called contextual factors. Diekmann and Presindörfer (2003) outlined the “low-cost hypothesis” which argues that pro-environmental behaviours are driven by pro-environmental attitudes only in the presence of low costs. However, little is known about households’ perceptions of costs and benefits in relation to energy saving behaviour. We propose to develop the low-cost hypothesis with a theoretical approach
integrating attitudinal research and rational choice literature and explaining the interaction between tangible and intangible costs and benefits.Furthermore, the importance of resources such as education, information and income is highlighted in order to explain the magnitude of the perception of the costs and benefits considered by households.
Finally, the scope for policy intervention aimed at shaping perceived costs and benefits to help the drive towards pro-environmental behaviour is discussed
On the low detection efficiency of disk water megamasers in Seyfert 2 AGN
Disk megamasers are a unique tool to study active galactic nuclei (AGN)
sub-pc environment, and precisely measure some of their fundamental parameters.
While the majority of disk megamasers are hosted in heavily obscured (i.e.,
Seyfert 2, Sy2) AGN, the converse is not true, and disk megamasers are very
rarely found even in obscured AGN. The very low detection rate of such systems
in Sy2 AGN could be due to the geometry of the maser beaming, which requires a
strict edge-on condition. We explore some other fundamental factors which could
play a role in a volume-limited survey of disk megamasers in Sy2 galaxies, most
importantly the radio luminosity.Comment: 2 pages, 2 figures. To appear in the Proceedings IAU Symposium No.
336, 2017 "Astrophysical Masers: Unlocking the Mysteries of the Universe
Typing actors using behavioural types
The actor model of computation assists and disciplines
the development of concurrent programs by forcing
the software engineer to reason about high-level concurrency
abstractions. While this leads to a better handling
of concurrency-related issues, the model itself does not exclude
erratic program behaviours. In this paper we consider
the actor model and investigate a type-based static analysis
to identify actor systems which may behave erraticly during
runtime. We consider the notion of behavioural types
and consider issues related to the nature of the actor model
including non-determinism, multi-party communication, dynamic
actor spawning, non-finite computation and a possibly
changing communication topology, which we contrast with
existing works.peer-reviewe
Towards A Theory Of Quantum Computability
We propose a definition of quantum computable functions as mappings between
superpositions of natural numbers to probability distributions of natural
numbers. Each function is obtained as a limit of an infinite computation of a
quantum Turing machine. The class of quantum computable functions is
recursively enumerable, thus opening the door to a quantum computability theory
which may follow some of the classical developments
A History of Until
Until is a notoriously difficult temporal operator as it is both existential
and universal at the same time: A until B holds at the current time instant w
iff either B holds at w or there exists a time instant w' in the future at
which B holds and such that A holds in all the time instants between the
current one and w'. This "ambivalent" nature poses a significant challenge when
attempting to give deduction rules for until. In this paper, in contrast, we
make explicit this duality of until to provide well-behaved natural deduction
rules for linear-time logics by introducing a new temporal operator that allows
us to formalize the "history" of until, i.e., the "internal" universal
quantification over the time instants between the current one and w'. This
approach provides the basis for formalizing deduction systems for temporal
logics endowed with the until operator. For concreteness, we give here a
labeled natural deduction system for a linear-time logic endowed with the new
operator and show that, via a proper translation, such a system is also sound
and complete with respect to the linear temporal logic LTL with until.Comment: 24 pages, full version of paper at Methods for Modalities 2009
(M4M-6
Quantum Turing Machines Computations and Measurements
Contrary to the classical case, the relation between quantum programming
languages and quantum Turing Machines (QTM) has not being fully investigated.
In particular, there are features of QTMs that have not been exploited, a
notable example being the intrinsic infinite nature of any quantum computation.
In this paper we propose a definition of QTM, which extends and unifies the
notions of Deutsch and Bernstein and Vazirani. In particular, we allow both
arbitrary quantum input, and meaningful superpositions of computations, where
some of them are "terminated" with an "output", while others are not. For some
infinite computations an "output" is obtained as a limit of finite portions of
the computation. We propose a natural and robust observation protocol for our
QTMs, that does not modify the probability of the possible outcomes of the
machines. Finally, we use QTMs to define a class of quantum computable
functions---any such function is a mapping from a general quantum state to a
probability distribution of natural numbers. We expect that our class of
functions, when restricted to classical input-output, will be not different
from the set of the recursive functions.Comment: arXiv admin note: substantial text overlap with arXiv:1504.02817 To
appear on MDPI Applied Sciences, 202
Dissipative behaviour of reinforced-earth retaining structures under severe ground motion
This paper focuses on the seismic performance of geosynthetic-reinforced retaining walls (GRWs) that several evidences have shown to be generally adequate. This can be attributed to the dissipation of energy produced by the internal plastic mechanisms activated during the seismic shaking, and to an overall ductile behaviour related to the large deformation that can be accommodated by the soil-reinforcement system. Using a number of numerical computations, this work compares the behaviour of three idealized structures that were conceived in order to have a similar seismic resistance, that however is activated through different plastic mechanisms. The analyses include numerical pseudo-static computations, carried out iteratively to failure, and time-domain nonlinear dynamic analyses, in which acceleration time-histories were applied to the bottom boundary of the same numerical models used for the pseudo-static analyses. The results of the dynamic analyses were interpreted in the light of the plastic mechanisms obtained with the pseudo-static procedure, confirming that GRWs develop local plastic mechanisms during strong motion resulting in a significant improvement of their seismic performance
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