72 research outputs found
Signals without teleology
"Signals" are a conceptual apparatus in many scientific disciplines. Biologists inquire about the evolution of signals, economists talk about the signaling function of purchases and prices, and philosophers discuss the conditions under which signals acquire meaning. However, little attention has been paid to what is a signal. This paper is an attempt to fill this gap with a definition of signal that avoids reference to form or purpose. Along the way we introduce novel notions of "information revealing" and "information concealing" moves in games. In the end, our account offers an alternative to teleological accounts of communication
Signals without teleology
"Signals" are a conceptual apparatus in many scientific disciplines. Biologists inquire about the evolution of signals, economists talk about the signaling function of purchases and prices, and philosophers discuss the conditions under which signals acquire meaning. However, little attention has been paid to what is a signal. This paper is an attempt to fill this gap with a definition of signal that avoids reference to form or purpose. Along the way we introduce novel notions of "information revealing" and "information concealing" moves in games. In the end, our account offers an alternative to teleological accounts of communication
Rare Decays
The rare decays of the meson have had a long tradition as a laboratory
for testing the symmetry properties of the weak interactions, and the manner in
which these symmetries are broken by higher order effects. Present--day
interest is focussed on decays that are suppressed by --symmetry or GIM
symmetry. Such decays, in the standard theory, are sensitive to effects of the
virtual top quark, and could also reveal new interactions transcending the
standard model. In addition, the radiative decays of the meson have become
a useful testing--ground for effective Lagrangians describing the low energy
interactions of pions, kaons and photons.Comment: Invited Talk at the Third Workshop on High Energy Particle Physics
(WHEPP 3) Madras, 1994, LaTex, 14 pages, 3 figures available upon reques
Cosmic Microwave Background constraint on residual annihilations of relic particles
Energy injected into the Cosmic Microwave Background at redshifts z<10^6 will
distort its spectrum permanently. In this paper we discuss the distortion
caused by annihilations of relic particles. We use the observational bounds on
deviations from a Planck spectrum to constrain a combination of annihilation
cross section, mass, and abundance. For particles with (s-wave) annihilation
cross section, =\sigma_0, the bound is
f[(\sigma_0/6e-27cm^3/s)(\Omega_{X\bar{X}}h^2)^2]/(m_X/MeV)<0.2, where m_X is
the particle mass, \Omega_{X\bar{X}} is the fraction of the critical density
the particle and its antiparticle contribute if they survive to the present
time, h=H_0/(100km/s/Mpc), H_0 is the Hubble constant, and f is the fraction of
the annihilation energy that interacts electromagnetically. We also compute the
less stringent limits for p-wave annihilation. We update other bounds on
residual annihilations and compare them to our CMB bound.Comment: submitted to Phys. Rev.
Relations between Financing and Output in the Not-for-Profit Hospital
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/68639/2/10.1177_107755878804500204.pd
Antiprotons in cosmic rays from neutralino annihilation
We calculate the antiproton flux due to relic neutralino annihilations, in a
two-dimensional diffusion model compatible with stable and radioactive cosmic
ray nuclei. We find that the uncertainty in the primary flux induced by the
propagation parameters alone is about two orders of magnitude at low energies,
and it is mainly determined by the lack of knowledge on the thickness of the
diffusive halo. On the contrary, different dark matter density profiles do not
significantly alter the flux: a NFW distribution produces fluxes which are at
most 20% higher than an isothermal sphere. The most conservative choice for
propagation parameters and dark matter distribution normalization, together
with current data on cosmic antiprotons, cannot lead to any definitive
constraint on the supersymmetric parameter space, neither in a low-energy
effective MSSM, or in a minimal SUGRA scheme. However, if the best choice for
propagation parameters - corresponding to a diffusive halo of L=4 kpc - is
adopted, some supersymmetric configurations with the neutralino mass of about
100 GeV should be considered as excluded. An enhancement flux factor - due for
instance to a clumpy dark halo or to a higher local dark matter density - would
imply a more severe cut on the supersymmetric parameters.Comment: 23 pages, 2 tables and 19 figures, typeset with ReVTeX4. The paper
may also be found at http://www.to.infn.it/~fornengo/papers/pbar03.ps.gz or
through http://www.to.infn.it/astropart/index.html A subsection added. Final
version to appear in PR
The evolution of language: a comparative review
For many years the evolution of language has been seen as a disreputable topic, mired in fanciful "just so stories" about language origins. However, in the last decade a new synthesis of modern linguistics, cognitive neuroscience and neo-Darwinian evolutionary theory has begun to make important contributions to our understanding of the biology and evolution of language. I review some of this recent progress, focusing on the value of the comparative method, which uses data from animal species to draw inferences about language evolution. Discussing speech first, I show how data concerning a wide variety of species, from monkeys to birds, can increase our understanding of the anatomical and neural mechanisms underlying human spoken language, and how bird and whale song provide insights into the ultimate evolutionary function of language. I discuss the ââdescended larynxâ â of humans, a peculiar adaptation for speech that has received much attention in the past, which despite earlier claims is not uniquely human. Then I will turn to the neural mechanisms underlying spoken language, pointing out the difficulties animals apparently experience in perceiving hierarchical structure in sounds, and stressing the importance of vocal imitation in the evolution of a spoken language. Turning to ultimate function, I suggest that communication among kin (especially between parents and offspring) played a crucial but neglected role in driving language evolution. Finally, I briefly discuss phylogeny, discussing hypotheses that offer plausible routes to human language from a non-linguistic chimp-like ancestor. I conclude that comparative data from living animals will be key to developing a richer, more interdisciplinary understanding of our most distinctively human trait: language
Mechanical characterization and modeling of polymeric materials for high-pressure sealing
Unraveling the contemporary drivers of renewable energy consumption: Evidence from regime types
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