scholarly journals Dust evolution, a global view I. Nanoparticles, nascence, nitrogen and natural selection … joining the dots

2016 ◽  
Vol 3 (12) ◽  
pp. 160221 ◽  
Author(s):  
A. P. Jones
Keyword(s):  
Natural Selection ◽  
Surface Chemistry ◽  
Interstellar Dust ◽  
Active Surface ◽  
Interstellar Clouds ◽  
Global View ◽  
Dust Evolution ◽  
Viable Model ◽  
Selection Of

The role and importance of nanoparticles for interstellar chemistry and beyond is explored within the framework of The Heterogeneous dust Evolution Model for Interstellar Solids (THEMIS), focusing on their active surface chemistry, the effects of nitrogen doping and the natural selection of interesting nanoparticle sub-structures. Nanoparticle-driven chemistry, and in particular the role of intrinsic epoxide-type structures, could provide a viable route to the observed gas phase OH in tenuous interstellar clouds en route to becoming molecular clouds. The aromatic-rich moieties present in asphaltenes probably provide a viable model for the structures present within aromatic-rich interstellar carbonaceous grains. The observed doping of such nanoparticle structures with nitrogen, if also prevalent in interstellar dust, could perhaps have important and observable consequences for surface chemistry and the formation of precursor pre-biotic species.

scholarly journals Dust evolution in the star forming turbulent interstellar medium

2006 ◽  
Vol 2 (S237) ◽  
pp. 47-52
Author(s):  
François Boulanger
Keyword(s):  
Interstellar Medium ◽  
Interstellar Dust ◽  
Dust Particles ◽  
Interstellar Clouds ◽  
Star Forming ◽  
Interstellar Turbulence ◽  
Star Forming Regions ◽  
Potential Impact ◽  
Dust Evolution ◽  
Small Dust

AbstractUnderstanding interstellar dust evolution is a major challenge underlying the interpretation of Spitzer observations of interstellar clouds, star forming regions and galaxies. I illustrate on-going work along two directions. I outline the potential impact of interstellar turbulence on the abundance of small dust particles in the diffuse interstellar medium and translucent sections of molecular clouds. I present results from an analysis of ISO and Spitzer observations of the central part of 30 Doradus, looking for dust evolution related to the radiative and dynamical impact of the R136 super star cluster on its parent molecular cloud.

Niche construction and the role of environment : towards a new logic of natural selection explanations

2015 ◽  
Author(s):  
◽  
Lynn (Chien-Hui Chiu) Chiu
Keyword(s):  
Natural Selection ◽  
Organization Theory ◽  
Niche Construction ◽  
University Of Missouri ◽  
External Conditions ◽  
The University ◽  
Population And Environment ◽  
Selection Of

[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT AUTHOR'S REQUEST.] I argue that natural selection explanations are not necessarily externalist, i.e. they don't always cite features of the environment as explanans. In the first chapter, I argue against the Propensity Interpretation of Fitness, which attributes fitness to internal abilities of individuals in a common environment, the latter dictating the selection of the population. However, for some populations, individuals construct different internal/external boundaries, preventing an explanatory boundary between internal and external at the level of the population. In the second chapter, I argue that niche construction, the ability of organisms to construct their experienced environments, can be either constitutive of or alternative to natural selection. Both reject explanatory externalism, a core feature of Adaptationism. An example of the latter is Niche Construction Theory, which decomposes population and environment into distinct evolutionary causes: Niche construction is from population to environment, while natural selection is from environment to population. An example of the former is Dialectical Biology and Situated Adaptationism, which show that population and environment resist decomposition into internal and environmental evolutionary causes. In the last chapter, I demonstrate that general Darwinism in organization theory explicitly assumes externalism. When organizations actively construct their conditions, the debates assume that natural selection do not occur or is ineffective. My previous analyses can show that selection occurs even when the organizations are constructing their external conditions.

Brownstock washing fundamentals: Enhancing drainage through chemistry — Part 2

TAPPI Journal ◽  
2014 ◽  
Vol 13 (3) ◽  
pp. 55-62
Author(s):  
TODD S. BOLTON ◽  
LLOYD A. LOBO ◽  
DANIEL NICHOLSON ◽  
ANDREW W. MCCLARY
Keyword(s):  
Surface Chemistry ◽  
Fiber Surface ◽  
Air Entrainment ◽  
Chemical Treatments ◽  
Entrained Air ◽  
Selection Of

The drainage of filtrates during mat formation in a brownstock washer directly impacts the washer’s productivity and indirectly affects its efficiency. In this paper, the role of entrained air on filtration through a formed mat during displacement as it occurs in brownstock washing was investigated. It was shown how chemical treatments, such as wash aids and fiber surface chemistry, influence air entrainment and, thereby, washer productivity and efficiency. By minimizing air entrained within a formed mat, displacement filtration rates and wash ratios were shown to improve. With this knowledge, washer operations can be improved through the design and selection of better treatments.

The Natural Selection of Minds

1998 ◽  
Vol 43 (4) ◽  
pp. 263-264
Author(s):  
Joseph F. Rychlak
Keyword(s):  
Natural Selection ◽  
Selection Of

Faculty selection of textbooks: Key variables and the role of teaching experience

2010 ◽  
Author(s):  
Aja Taitano ◽  
Bradley Smith ◽  
Cade Hulbert ◽  
Kristin Batten ◽  
Lalania Woodstrom ◽  
...  
Keyword(s):  
Teaching Experience ◽  
Key Variables ◽  
Faculty Selection ◽  
Selection Of
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