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ref: -0 tags: optical gain media lasers cross section dye date: 06-13-2019 15:13 gmt revision:2 [1] [0] [head]

Eminently useful. Source: https://ocw.mit.edu/courses/electrical-engineering-and-computer-science/6-974-fundamentals-of-photonics-quantum-electronics-spring-2006/lecture-notes/chapter7.pdf

Laser Dye technology by Peter Hammond

  • This paper is another great resource!
  • Lists the stimulated emission cross-section for Rhodamine-6G as 4e-16 @ 550nm, consistent with the table above.
  • At a (high) concentration of 2mMol (1 g/l), 1/e penetration depth is 20um.
    • Depending on the solvent, there may be aggregation and stacking / quenching.
  • Tumbling time of Rhodamine 6G in ethanol is 20 to 300ps; fluorescence lifetime in oscillators is 10's of ps, so there is definitely polarization sensitive amplification.
  • Generally in dye lasers, the emission cross-section must be higher than the excited state absorption, σ eσ \sigma_e - \sigma^\star most important.
  • Bacteria can actually subsist on rhodamine-similar sulfonated dyes in aqueous solutions! Wow.

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ref: -0 tags: recurrent cortical model adaptation gain V1 LTD date: 03-27-2018 17:48 gmt revision:1 [0] [head]

PMID-18336081 Adaptive integration in the visual cortex by depressing recurrent cortical circuits.

  • Mainly focused on the experimental observation that decreasing contrast increases latency to both behavioral and neural response (latter in the later visual areas..)
  • Idea is that synaptic depression in recurrent cortical connections mediates this 'adaptive integration' time-constant to maintain reliability.
  • Model also explains persistent activity after a flashed stimulus.
  • No plasticity or learning, though.
  • Rather elegant and well explained.

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ref: Bassett-2009.07 tags: Weinberger congnitive efficiency beta band neuroimagaing EEG task performance optimization network size effort date: 12-28-2011 20:39 gmt revision:1 [0] [head]

PMID-19564605[0] Cognitive fitness of cost-efficient brain functional networks.

  • Idea: smaller, tighter networks are correlated with better task performance
    • working memory task in normal subjects and schizophrenics.
  • Larger networks operate with higher beta frequencies (more effort?) and show less efficient task performance.
  • Not sure about the noisy data, but v. interesting theory!

____References____

[0] Bassett DS, Bullmore ET, Meyer-Lindenberg A, Apud JA, Weinberger DR, Coppola R, Cognitive fitness of cost-efficient brain functional networks.Proc Natl Acad Sci U S A 106:28, 11747-52 (2009 Jul 14)