8,596 research outputs found
The art of being human : a project for general philosophy of science
Throughout the medieval and modern periods, in various sacred and secular guises, the unification of all forms of knowledge under the rubric of ‘science’ has been taken as the prerogative of humanity as a species. However, as our sense of species privilege has been called increasingly into question, so too has the very salience of ‘humanity’ and ‘science’ as general categories, let alone ones that might bear some essential relationship to each other. After showing how the ascendant Stanford School in the philosophy of science has contributed to this joint demystification of ‘humanity’ and ‘science’, I proceed on a more positive note to a conceptual framework for making sense of science as the art of being human. My understanding of ‘science’ is indebted to the red thread that runs from Christian theology through the Scientific Revolution and Enlightenment to the Humboldtian revival of the university as the site for the synthesis of knowledge as the culmination of self-development. Especially salient to this idea is science‘s epistemic capacity to manage modality (i.e. to determine the conditions under which possibilities can be actualised) and its political capacity to organize humanity into projects of universal concern. However, the challenge facing such an ideal in the twentyfirst century is that the predicate ‘human’ may be projected in three quite distinct ways, governed by what I call ‘ecological’, ‘biomedical’ and ‘cybernetic’ interests. Which one of these future humanities would claim today’s humans as proper ancestors and could these futures co-habit the same world thus become two important questions that general philosophy of science will need to address in the coming years
Cartan Triples
We introduce the class of Cartan triples as a generalization of the notion of
a Cartan MASA in a von Neumann algebra. We obtain a one-to-one correspondence
between Cartan triples and certain Clifford extensions of inverse semigroups.
Moreover, there is a spectral theorem describing bimodules in terms of their
support sets in the fundamental inverse semigroup and, as a corollary, an
extension of Aoi's theorem to this setting. This context contains that of
Fulman's generalization of Cartan MASAs and we discuss his generalization in an
appendix.Comment: 37 page
A 15kWe (nominal) solar thermal electric power conversion concept definition study: Steam Rankine reheat reciprocator system
An evaluation was made of the potential of a steam Rankine reheat reciprocator engine to operate at high efficiency in a point-focusing distributed receiver solar thermal-electric power system. The scope of the study included the engine system and electric generator; not included was the solar collector/mirror or the steam generator/receiver. A parametric analysis of steam conditions was completed leading to the selection of 973 K 12.1 MPa as the steam temperature/pressure for a conceptual design. A conceptual design was completed for a two cylinder/ opposed engine operating at 1800 rpm directly coupled to a commercially available induction generator. A unique part of the expander design is the use of carbon/graphite piston rings to eliminate the need for using oil as an upper cylinder lubricant. The evaluation included a system weight estimate of 230 kg at the mirror focal point with the condenser mounted separately on the ground. The estimated cost of the overall system is 90/kW for the maximum 26 kW output
Public geographies II: being organic
This second report on ‘public geographies' considers the diverse, emergent and shifting spaces of engaging with and in public/s. Taking as its focus the more ‘organic’ rather than ‘traditional’ approach to doing public geography, as discussed in the first report, it explores the multiple and unorthodox ways in which engagements across academic-public spheres play out, and what such engagements may mean for geography/ers. The report first explores the role of the internet in ‘enabling conversations', generating a range of opportunities for public geography through websites, wikis, blogs, file-sharing sites, discussion forums and more, thinking critically about how technologies may enable/disable certain kinds of publically engaged activities. It then considers issues of process and praxis: how collaborations with groups/communities/organizations beyond academia are often unplanned, serendipitous encounters that evolve organically into research/learning/teaching endeavours; but also that personal politics/positionality bring an agency to bear upon whether we, as academics, follow the leads we may stumble upon. The report concludes with a provocative question – given that many non-academics appear to be doing some amazing and inspiring projects and activities, thoughtful, critical and (arguably) examples of organic public geographies, what then is academia’s role
MSW-like Enhancements without Matter
We study the effects of a scalar field, coupled only to neutrinos, on
oscillations among weak interaction current eigenstates. The effect of a real
scalar field appears as effective masses for the neutrino mass eigenstates, the
same for \nbar as for \n. Under some conditions, this can lead to a
vanishing of , giving rise to MSW-like effects. We discuss some
examples and show that it is possible to resolve the apparent discrepancy in
spectra required by r-process nucleosynthesis in the mantles of supernovae and
by Solar neutrino solutions.Comment: 9 pages, latex, 1 figur
Neutrino-Neutrino Scattering and Matter-Enhanced Neutrino Flavor Transformation in Supernovae
We examine matter-enhanced neutrino flavor transformation
() in the region above the neutrino
sphere in Type II supernovae. Our treatment explicitly includes contributions
to the neutrino-propagation Hamiltonian from neutrino-neutrino forward
scattering. A proper inclusion of these contributions shows that they have a
completely negligible effect on the range of - vacuum
mass-squared difference, , and vacuum mixing angle, , or
equivalently , required for enhanced supernova shock re-heating.
When neutrino background effects are included, we find that -process
nucleosynthesis from neutrino-heated supernova ejecta remains a sensitive probe
of the mixing between a light and a with a
cosmologically significant mass. Neutrino-neutrino scattering contributions are
found to have a generally small effect on the
parameter region probed by -process nucleosynthesis. We point out that the
nonlinear effects of the neutrino background extend the range of sensitivity of
-process nucleosynthesis to smaller values of .Comment: 38 pages, tex, DOE/ER/40561-150-INT94-00-6
The retting of hemp I. Field retting of hemp in Iowa
Hemp was planted in Iowa in 1943 and ] 944 as a war emergency crop under a program planned to meet expected shortages of cordage fibers resulting from the loss of the Philippines and the Dutch East Indies to Japan in 1942. There was no general previous experience with this crop in the state, and as much as 45,000 acres grouped around 11 mill sites in the north-central counties were called for in the first season. A small acreage of domestic hemp had been produced in Wisconsin and Kentucky for many years so that there was a considerable volume of information as to the cultural and management practices required. That soil and climatic conditions in Iowa. would be reasonably suitable for the growth of this crop was not doubted, and this was confirmed by successful small experimental plantings in 1942. There was some doubt, however, whether the moisture conditions in the fall would be as suitable for the retting of the straw as in the hemp area in Wisconsin
Simulation of primordial object formation
We have included the chemical rate network responsible for the formation of
molecular Hydrogen in the N-body hydrodynamic code, Hydra, in order to study
the formation of the first cosmological at redshifts between 10 and 50. We have
tested our implementation of the chemical and cooling processes by comparing
N-body top hat simulations with theoretical predictions from a semi-analytic
model and found them to be in good agreement. We find that post-virialization
properties are insensitive to the initial abundance of molecular hydrogen. Our
main objective was to determine the minimum mass () of perturbations
that could become self gravitating (a prerequisite for star formation), and the
redshift at which this occurred. We have developed a robust indicator for
detecting the presence of a self-gravitating cloud in our simulations and find
that we can do so with a baryonic particle mass-resolution of 40 solar masses.
We have performed cosmological simulations of primordial objects and find that
the object's mass and redshift at which they become self gravitating agree well
with the results from the top hat simulations. Once a critical
molecular hydrogen fractional abundance of about 0.0005 has formed in an
object, the cooling time drops below the dynamical time at the centre of the
cloud and the gas free falls in the dark matter potential wells, becoming self
gravitating a dynamical time later.Comment: 45 pages, 17 figures, submitted to Ap
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