Spatial relationships between the terminations of somatic sensory and motor pathways in the rostral brainstem of cats and monkeys. I. Ascending somatic sensory inputs to lateral diencephalon

Higher-order structure in abiotic foldamer systems represents an important but largely unrealized goal. As one approach to this challenge, covalent assembly can be used to assemble macrocycles with foldamer subunits in well-defined spatial relationships. Such systems have previously been shown to exhibit self-sorting, new folding motifs, and dynamic stereoisomerism, yet there remain important questions about the interplay between folding and macrocyclization and the effect of structural confinement on folding behavior. Here, we explore the dynamic covalent assembly of extended ortho-phenylenes (hexamer and decamer) with rod-shaped linkers. Characteristic 1H chemical shift differences between cyclic and acyclic systems can be compared with computational conformer libraries to determine the folding states of the macrocycles. We show that the bite angle provides a measure of the fit of an o-phenylene conformer within a shape-persistent macrocycle, affecting both assembly and ultimate folding behavior. For the o-phenylene hexamer, the bite angle and conformer stability work synergistically to direct assembly toward triangular [3+3] macrocycles of well-folded oligomers. For the decamer, the energetic accessibility of conformers with small bite angles allows [2+2] macrocycles to be formed as the predominant species. In these systems, the o-phenylenes are forced into unusual folding states, preferentially adopting a backbone geometry with distinct helical blocks of opposite handedness. The results show that simple geometric restrictions can be used to direct foldamers toward increasingly complex geometries.

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Macrocycles of Higher ortho-Phenylenes: Assembly and Folding

10.26434/chemrxiv.8085143 ◽

2019 ◽

Author(s):

Zacharias Kinney ◽

Viraj Kirinda ◽

Scott Hartley

Keyword(s):

Chemical Shift ◽

Higher Order ◽

Order Structure ◽

Complex Geometries ◽

Spatial Relationships ◽

Predominant Species ◽

Bite Angle ◽

Direct Assembly

Higher-order structure in abiotic foldamer systems represents an important but largely unrealized goal. As one approach to this challenge, covalent assembly can be used to assemble macrocycles with foldamer subunits in well-defined spatial relationships. Such systems have previously been shown to exhibit self-sorting, new folding motifs, and dynamic stereoisomerism, yet there remain important questions about the interplay between folding and macrocyclization and the effect of structural confinement on folding behavior. Here, we explore the dynamic covalent assembly of extended ortho-phenylenes (hexamer and decamer) with rod-shaped linkers. Characteristic 1H chemical shift differences between cyclic and acyclic systems can be compared with computational conformer libraries to determine the folding states of the macrocycles. We show that the bite angle provides a measure of the fit of an o-phenylene conformer within a shape-persistent macrocycle, affecting both assembly and ultimate folding behavior. For the o-phenylene hexamer, the bite angle and conformer stability work synergistically to direct assembly toward triangular [3+3] macrocycles of well-folded oligomers. For the decamer, the energetic accessibility of conformers with small bite angles allows [2+2] macrocycles to be formed as the predominant species. In these systems, the o-phenylenes are forced into unusual folding states, preferentially adopting a backbone geometry with distinct helical blocks of opposite handedness. The results show that simple geometric restrictions can be used to direct foldamers toward increasingly complex geometries.

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Triggers of Thought: Impressions within Hume’s Theory of Mind

History of Philosophy and Logical Analysis ◽

10.30965/26664275-01301007 ◽

2010 ◽

Vol 13 (1) ◽

pp. 105-121

Author(s):

Anik Waldow

Keyword(s):

Theory Of Mind ◽

Associative Processes ◽

Sensory Inputs ◽

The World ◽

Theories Of Meaning ◽

Conceptual Resources

This essay argues that Humean impressions are triggers of associative processes, which enable us to form stable patterns of thought that co-vary with our experiences of the world. It will thus challenge the importance of the Copy Principle by claiming that it is the regularity with which certain kinds of sensory inputs motivate certain sets of complex ideas that matters for the discrimination of ideas. This reading is conducive to Hume’s account of perception, because it avoids the impoverishment of conceptual resources so typical for empiricist theories of meaning and explains why ideas should be based on impressions, although impressions cannot be known to mirror matters of fact. Dieser Aufsatz argumentiert dafür, dass humesche Eindrücke („impressions“) Auslöser von assoziativen Prozessen sind, welche es uns ermöglichen, stabile Denkmuster zu bilden, die mit unseren Erfahrungen der Welt kovariant sind. Der Aufsatz stellt somit die Wichtigkeit des Kopien-Prinzips in Frage, nämlich dadurch, dass behauptet wird, für die Unterscheidung der Ideen sei die Regelmäßigkeit maßgeblich, mit der gewisse Arten von sensorischen Eingaben gewisse Mengen von komplexen Ideen motivieren. Diese Lesart trägt zu einem Verständnis von Humes Auffassung der Wahrnehmung bei, da sie die Verarmung der begrifflichen Mittel, die für empiristische Theorien der Bedeutung so typisch ist, vermeidet und erklärt, warum Ideen auf Eindrücken basieren sollten, obwohl Eindrücke nicht als Abbildungen von Tatsachen erkannt werden können.

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