20,506 research outputs found
Kolmogorov-Burgers Model for Star Forming Turbulence
The process of star formation in interstellar molecular clouds is believed to
be controlled by driven supersonic magnetohydrodynamic turbulence. We suggest
that in the inertial range such turbulence obeys the Kolmogorov law, while in
the dissipative range it behaves as Burgers turbulence developing shock
singularities. On the base of the She-Leveque analytical model we then predict
the velocity power spectrum in the inertial range to be E_k ~ k^{-1.74}. This
result reproduces the observational Larson law, ~ l^{0.74...0.76},
[Larson, MNRAS 194 (1981) 809] and agrees well with recent numerical findings
by Padoan and Nordlund [astro-ph/0011465]. The application of the model to more
general dissipative structures, with higher fractal dimensionality, leads to
better agreement with recent observational results.Comment: revised, new material added, 8 page
Hayashi and the Thermal Physics of Star-Forming Clouds
This brief historical review highlights the early work of Hayashi and his
associates on the thermal physics of star-forming clouds, as summarized in the
temperature-density diagrams first presented by this group. Some of the more
recent developments in this subject, including its application to understanding
stellar masses and to understanding the formation of the first stars, are also
briefly reviewed.Comment: Presented at the meeting on "First Stars IV" in Kyoto, Japan, May
21-25, 2012, honoring Chushiro Hayash
Adapting Human Rights
Governmental leaders, scholars, and activists have advocated for human rights to food, water, education, health care, and energy. Such rights, also called positive rights, place an affirmative duty upon the state to provide a minimum quantity and quality of these goods and services to all citizens. But food, education, water, and health care are so different–in how they are produced, consumed, and financed–that the implementation of a positive right must be adapted to the distinctive characteristics of the good or service it guarantees. The primary aims of this adaptive implementation are transparency, enforceability and sustainability in the provision of positive rights. Only by adapting a positive right to its policy environment can such a right function as a viable means of protecting disadvantaged members of society. This article uses the example of positive rights to public utilities, such as water and energy, to illustrate adaptive implementation of positive rights. In doing so, this article explains why and how a positive right must be adapted to the unique policy environment of a given public utility
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