3,964 research outputs found
Aristotle, potential and actual, conflicts
In The Metaphysics Book Theta, Chapter four, Aristotle claims that to state that “some
X is possible but X will never be” is a mistake. In effect, he collapses the possible into
the actual. This view conflicts with the existence of dispositions which I argue exist,
as they are indispensable to science. In Theta Chapter three, Aristotle sets out a test of
possibility whereby we assume that some entity exists and then see if an impossibility
ensues. I apply this test to Aristotle’s theory and show that it entails the impossibility
of dispositions. Given the clear existence of dispositions, Aristotle’s conflation of the
possible with the actual fails his own test of possibility and must be wrong
Some Future Contingents and Aristotle.
Aristotle argued that particular statements about the future were neither true nor false. Turner rejects this claim, arguing that implicit to such a theory is an untenable theory of time. Whilst developing a theory of time was not Aristotle’s intent, Turner believes his view does entail an ontology that is questionable at best. Once we have sorted out an acceptable theory of time, the only reasonable conclusions about all statements is that they are true or false. That we do not know whether our statements about the
future are true or false is an epistemological problem. This claim is aimed at those (not necessarily Aristotle) who wish to adopt Aristotle’s view today
Turbulence in the solar wind
The solar wind provides a unique natural "laboratory" in which plasma turbulence
may be investigated in-situ. Turbulence is statistically reproducible. Thus,
in this thesis we investigate plasma turbulence in the solar wind through the statistical
study of magnetic field observations. In particular, we investigate single-satellite
time-series of the magnetic field.
We discuss hydrodynamic turbulence, and make parallels between hydrodynamic
and magnetohydrodynamic turbulence. In hydrodynamic turbulence a unique
scaling relation may be determined from dimensional analysis. Importantly, one may
not derive a unique scaling relation for magnetohydrodynamic turbulence from dimensional
analysis. Therefore, comparison of observations and turbulence models
are key to determining the underlying physics for specific plasma parameters.
The inertial range is a range of scales over which energy cascades from large
to small temporal-spatial scales. This thesis will predominantly be focused on the
anisotropy and scaling of the inertial range within the solar wind. We investigate
how sampling a solenoid field, i.e. . B = 0, with a single satellite produces
an apparent nonaxisymmetry with respect to the background magnetic field. We
also investigate how time-series discontinuities produced by non-turbulent structures
alter the statistical analysis of various anisotropy measures. We will find that the
commonly held picture of the solar wind, that specific temporal-spatial scales have a
distinct physical origin, is an over simplified model. We will show that non-turbulent
structures must be removed from the observations in order to analysis the statistics
of the turbulence accurately. The work in this thesis helps to constrain theories
of plasma turbulence where there is a background magnetic field with a greater
magnitude than the root-mean-square magnitude of the turbulent
fluctuations
An intelligent framework and prototype for autonomous maintenance planning in the rail industry
This paper details the development of the AUTONOM project, a project that aims to provide an enterprise system tailored to the planning needs of the rail industry. AUTONOM extends research in novel sensing, scheduling, and decision-making strategies customised for the automated planning of maintenance activities within the rail industry. This paper sets out a framework and software prototype and details the current progress of the project. In the continuation of the AUTONOM project it is anticipated that the combination of techniques brought together in this work will be capable of addressing a wider range of problem types, offered by Network rail and organisations in different industries
Biobank Economics and the “Commercialization Problem”
The economic aspects of biobanking are intertwined with the social and scientific aspects. We describe two problems that structure the discussion about the economics of biobanking and which illustrate this intertwining. First, there is a ‘sustainability problem’ about how to maintain biobanks in the long term. Second, and representing a partial response to the first problem, there is a ‘commercialisation problem’ about how to deal with the voluntary altruistic relationship between participants and biobanks, and the potential commercial relationships that a biobank may form. Social scientists have argued that the commercialisation problem is inadequate as a way to construct the multiple tensions that biobanks must negotiate. We agree that the commercialisation problem is an inadequate framework; turning to alternative accounts of bioeconomy, we suggest that contemporary consideration of the economics of biobanking primarily in terms of participants and their bodily tissue may reproduce the very commodification of science that these scholars critique. We suggest that an alternative conception of the economics of biobanking beyond the logics of commodification, which may thereby allow broader questions about the social and economic conditions and consequences of biobanks to be posed
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Local and remote impacts of aerosol species on Indian summer monsoon rainfall in a GCM
The HadGEM2 AGCM is used to determine the most important anthropogenic aerosols in the Indian monsoon using experiments in which observed trends in individual aerosol species are imposed. Sulphur dioxide (SD) emissions are shown to impact rainfall more strongly than black carbon (BC) aerosols, causing reduced rainfall especially over northern India. Significant perturbations due to BC are not noted until its emissions are scaled up in a sensitivity test, resulting in rainfall increases over northern India due to the Elevated Heat Pump mechanism, enhancing convection during the pre-monsoon and bringing forward the monsoon onset. Secondly, the impact of anthropogenic aerosols is compared to that of increasing greenhouse-gas concentrations and observed sea-surface temperature (SST) warming. The tropospheric temperature gradient driving the monsoon shows weakening when forced
by either SD or imposed SST trends. However the observed SST trend is dominated by warming in the deep tropics; when the component of SST trend related to aerosol emissions is removed, further warming is found in the extratropical northern hemisphere that tends to offset monsoon weakening. This suggests caution is needed when using SST forcing as a proxy for greenhouse warming. Finally, aerosol
emissions are decomposed into those from the Indian region and those elsewhere, in pairs of experiments with SD and BC. Both local and remote aerosol emissions are found to lead to rainfall changes over India; for SD, remote aerosols contribute around 75% of the rainfall decrease over India, while for BC the remote forcing is even more
dominant
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