Giving and Receiving Peer Advice in an Online Breast Cancer Support Group

People have access to experiential information and advice about health online. The types of advice exchanged affect the nature of online communities and potentially patient decision making. The aim of this study was to examine the ways in which peers exchange advice within an online health forum in order to better understand online groups as a resource for decision making. Messages collected over a one-month period from an online breast cancer support forum were analyzed for examples of advice exchange. The majority of the messages solicited advice through problem disclosure or requests for information and opinion. A novel form of advice solicitation—“anyone in the same boat as me”—was noted as was the use of personal experience as a form of advice giving. Women construct their advice requests to target like-minded people. The implications in terms of decision making and support are discussed

Neutrino masses in quartification schemes

The idea of quark-lepton universality at high energies has recently been explored in unified theories based upon the quartification gauge group SU(3)^4. These schemes encompass a quark-lepton exchange symmetry that results upon the introduction of leptonic colour. It has been demonstrated that in models in which the quartification gauge symmetry is broken down to the standard model gauge group, gauge coupling constant unification can be achieved, and there is no unique scenario. The same is also true when the leptonic colour gauge group is only partially broken, leaving a remnant SU(2)_\ell symmetry at the standard model level. Here we perform an analysis of the neutrino mass spectrum of such models. We show that these models do not naturally generate small Majorana neutrino masses, thus correcting an error in our earlier quartification paper, but with the addition of one singlet neutral fermion per family there is a realisation of see-saw suppressed masses for the neutrinos. We also show that these schemes are consistent with proton decay.Comment: 12 pages, minor changes. To appear in Phys. Rev.

High-resolution simulations of the final assembly of Earth-like planets 2: water delivery and planetary habitability

The water content and habitability of terrestrial planets are determined during their final assembly, from perhaps a hundred 1000-km "planetary embryos" and a swarm of billions of 1-10 km "planetesimals." During this process, we assume that water-rich material is accreted by terrestrial planets via impacts of water-rich bodies that originate in the outer asteroid region. We present analysis of water delivery and planetary habitability in five high-resolution simulations containing about ten times more particles than in previous simulations (Raymond et al 2006a, Icarus, 183, 265-282). These simulations formed 15 terrestrial planets from 0.4 to 2.6 Earth masses, including five planets in the habitable zone. Every planet from each simulation accreted at least the Earth's current water budget; most accreted several times that amount (assuming no impact depletion). Each planet accreted at least five water-rich embryos and planetesimals from past 2.5 AU; most accreted 10-20 water-rich bodies. We present a new model for water delivery to terrestrial planets in dynamically calm systems, with low-eccentricity or low-mass giant planets -- such systems may be very common in the Galaxy. We suggest that water is accreted in comparable amounts from a few planetary embryos in a "hit or miss" way and from millions of planetesimals in a statistically robust process. Variations in water content are likely to be caused by fluctuations in the number of water-rich embryos accreted, as well as from systematic effects such as planetary mass and location, and giant planet properties.Comment: Astrobiology, in pres

The frequency of muscle protein polymorphism in Menidia menidia (Atherinidae) along the Atlantic coast

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Cosmological constant in scale-invariant theories

The incorporation of a small cosmological constant within radiatively-broken scale-invariant models is discussed. We show that phenomenologically consistent scale-invariant models can be constructed which allow a small positive cosmological constant, providing certain relation between the particle masses is satisfied. As a result, the mass of the dilaton is generated at two-loop level. Another interesting consequence is that the electroweak symmetry-breaking vacuum in such models is necessarily a metastable `false' vacuum which, fortunately, is not expected to decay on cosmological time scales.Comment: 10 pages; v2: clarifying remarks added, to appear in Physical Review

Neuronal Distortions of Reward Probability without Choice

Reward probability crucially determines the value of outcomes. A basic phenomenon, defying explanation by traditional decision theories, is that people often overweigh small and underweigh large probabilities in choices under uncertainty. However, the neuronal basis of such reward probability distortions and their position in the decision process are largely unknown. We assessed individual probability distortions with behavioral pleasantness ratings and brain imaging in the absence of choice. Dorsolateral frontal cortex regions showed experience dependent overweighting of small, and underweighting of large, probabilities whereas ventral frontal regions showed the opposite pattern. These results demonstrate distorted neuronal coding of reward probabilities in the absence of choice, stress the importance of experience with probabilistic outcomes and contrast with linear probability coding in the striatum. Input of the distorted probability estimations to decision-making mechanisms are likely to contribute to well known inconsistencies in preferences formalized in theories of behavioral economics