1,340,370 research outputs found
Possible Effects of the Existence of the 4th Generation Neutrino
The 4th generation of fermions predicted by the phenomenology of heterotic
string models can possess new strictly conserved charge, which leads, in
particular, to the hypothesis of the existence of the 4th generation massive
stable neutrino. The compatibility of this hypothesis with the results of
underground experiment DAMA searching for weakly interactive particles of dark
matter and with the EGRET measurements of galactic gamma--background at
energies above 1 GeV fixes the possible mass of the 4th neutrino at the value
about 50 GeV. The possibility to test the hypothesis in accelerator experiments
is considered. Positron signal from the annihilation of relic massive neutrinos
in the galactic halo is calculated and is shown to be accessible for planned
cosmic ray experiments.Comment: 10 pages, 4 PostScript figure, Latex2
Magnetic Inhibition of Convection and the Fundamental Properties of Low-Mass Stars. II. Fully Convective Main Sequence Stars
We examine the hypothesis that magnetic fields are inflating the radii of
fully convective main sequence stars in detached eclipsing binaries (DEBs). The
magnetic Dartmouth stellar evolution code is used to analyze two systems in
particular: Kepler-16 and CM Draconis. Magneto-convection is treated assuming
stabilization of convection and also by assuming reductions in convective
efficiency due to a turbulent dynamo. We find that magnetic stellar models are
unable to reproduce the properties of inflated fully convective main sequence
stars, unless strong interior magnetic fields in excess of 10 MG are present.
Validation of the magnetic field hypothesis given the current generation of
magnetic stellar evolution models therefore depends critically on whether the
generation and maintenance of strong interior magnetic fields is physically
possible. An examination of this requirement is provided. Additionally, an
analysis of previous studies invoking the influence of star spots is presented
to assess the suggestion that star spots are inflating stars and biasing light
curve analyses toward larger radii. From our analysis, we find that there is
not yet sufficient evidence to definitively support the hypothesis that
magnetic fields are responsible for the observed inflation among fully
convective main sequence stars in DEBs.Comment: Accepted for publication in ApJ, 17 pages, 11 figures, 2 table
An item/order tradeoff explanation of word length and generation effects
[Abstract]: The item-order hypothesis suggests that under certain conditions increased item processing can lead to deficits in order processing, and that this produces a dissociation in performance between item and order tasks. The generation effect is one such example. The word length effect is seen as another instance where this tradeoff might be observed. The following experiments compare word length and generation effects under serial recall and single item recognition conditions. Short words are better recalled than long words on the serial recall task but long words were better recognised than short words. The results are consistent with the item-order approach and support a novel explanation for the word length effect
The Interaction Between FDI and Infrastructure Capital in The Development Process
This paper focuses on the possible interaction between foreign direct investment (FDI) and the host country’s infrastructure base. Its central hypothesis is that the effect of FDI on per capita real income depends, at least in part, on the size of the recipient country’s infrastructure. This hypothesis is tested in a panel of 46 countries and 5-year averages over the 1980–2000 period using the size of three types of infrastructure capital: telecommunication, power generation, and network of roads or highways. The results indicate that the size of the host country’s infrastructure base helps to improve the marginal effect of FDI on real income
Inverse relationship between genetic diversity and epigenetic complexity
Early studies of molecular evolution revealed a correlation between genetic distance and time of species divergence. This observation provoked the molecular clock hypothesis and in turn the ‘Neutral Theory’, which however remains an incomplete explanation since it predicts a constant mutation rate per generation whereas empirical evidence suggests a constant rate per year. Data inconsistent with the molecular clock hypothesis have steadily accumulated in recent years that show no correlation between genetic distance and time of divergence. It has therefore become a challenge to find a testable idea that can reconcile the seemingly conflicting data sets. Here, an inverse relationship between genetic diversity and epigenetic complexity was deduced from a simple intuition in building complex systems. Genetic diversity, i.e., genetic distance or dissimilarity in DNA or protein sequences between individuals or species, is restricted by the complexity of epigenetic programs. This inverse relationship logically deduces the maximum genetic diversity hypothesis, which suggests that macroevolution from simple to complex organisms involves a punctuational increase in epigenetic complexity that in turn causes a punctuational loss in genetic diversity. The hypothesis explains a diverse set of biological phenomena, including both for and against the correlation between genetic distance and time of divergence.

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