32,639 research outputs found
Emergence, hierarchy and top-down causation in evolutionary biology
The concept of emergence and the related notion of âdownward causationâ have arisen in numerous branches of science, and have also been extensively discussed in philosophy. Here, I examine emergence and downward causation in relation to evolutionary biology. I focus on the old, but ongoing discussion in evolutionary biology over the âlevels of selectionâ question: which level(s) of the biological hierarchy natural selection acts at, e.g. the gene, individual, group or species level? The concept of emergence has arisen in the levels-of-selection literature as a putative way of distinguishing between âtrueâ selection at a higher level from cases where selection acts solely at the lower level but has effects that percolate up the biological hierarchy, generating the appearance of higher level selection. At first blush, this problem seems to share a common structure with debates about emergence in other areas, but closer examination shows that it turns on issues that are sui generis to biology
Cognitive Semantics: An Extension of the Cartesian Legacy
The basic intention of this article is to show how the cognitive semantics inherits its ancestry from the Cartesian foundation. The emergence of the cognitive semantics is envisaged here as an integral part of the knowledge evolution, in terms of shifts, which ultimately determines the future direction of our epistemological quest. Basically two questions have been emphasized here: (a) how (and what amount of) common sense metaphysics can be incorporated within the existing system of knowledge; and (b) is there any substratum where the mind-body dualism can be boiled down
Theory of Scanning Tunneling Microscopy
This lecture has been given at the 45th Spring School: Computing Solids:
Models, Ab-initio Methods and Supercomputing organized at the Forschungszentrum
J\"ulich. The goal of this manuscript is to review the basics behind the theory
accompanying Scanning Tunneling Microscopy.Comment: 38 pages, 45th IFF Spring School: Computing Solids: Models, Ab-initio
Methods and Supercomputing organized at the research center of Juelic
Green Valley Galaxies
The "green valley" is a wide region separating the blue and the red peaks in
the ultraviolet-optical color magnitude diagram, first revealed using GALEX UV
photometry. The term was coined by Christopher Martin in 2005. Green valley
highlights the discriminating power of UV to very low relative levels of
ongoing star formation, to which the optical colors, including u-r, are
insensitive. It corresponds to massive galaxies below the star-forming "main"
sequence, and therefore represents a critical tool for the study of the
quenching of star formation and its possible resurgence in otherwise quiescent
galaxies. This article reviews the results pertaining to morphology, structure,
environment, dust content and gas properties of green valley galaxies in the
local universe. Their relationship to AGN is also discussed. Attention is given
to biases emerging from defining the "green valley" using optical colors. We
review various evolutionary scenarios and we present evidence for a new,
quasi-static view of the green valley, in which the majority of galaxies
currently in the green valley were only partially quenched in the distant past
and now participate in a slow cosmic decline of star formation, which also
drives down the activity on the main sequence, presumably as a result of the
dwindling accretion/cooling onto galaxy disks.Comment: Invited review. 13 pages. Comments welcom
The Canadian Unemployment Insurance Generosity: Reflections from a Comparative Analysis
The unemployment compensation system is at the centre of the current economic and political debate in many Western countries which, under the effects of the increase in public debt, must decide the level of their unemployment insurance while taking into account its impact on the performance of the labour market. In this article, we compare the generosity of such public policy in France and in Canada, while focusing on the experience of central and eastern Europe. By building a composite index, we show that the French unemployment insurance is more generous only in pecuniary terms, and not in its qualitative dimension
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