69 research outputs found
Many Faces of Entropy or Bayesian Statistical Mechanics
Some 80-90 years ago, George A. Linhart, unlike A. Einstein, P. Debye, M.
Planck and W. Nernst, has managed to derive a very simple, but ultimately
general mathematical formula for heat capacity vs. temperature from the
fundamental thermodynamical principles, using what we would nowadays dub a
"Bayesian approach to probability". Moreover, he has successfully applied his
result to fit the experimental data for diverse substances in their solid state
in a rather broad temperature range. Nevertheless, Linhart's work was
undeservedly forgotten, although it does represent a valid and fresh standpoint
on thermodynamics and statistical physics, which may have a significant
implication for academic and applied science.Comment: submitte
90 GHz Continuum Observations of Messier 66
Radio emission at around 90 GHz from star-forming galaxies is expected to be
strongly dominated by the free-free component due to ionising radiation from
massive, short-lived, stars. We present high surface-brightness sensitivity
observations at 90 GHz of the nearby star-forming galaxy Messier 66 with
resolution of about 9 arcsec (corresponding to a physical scale of about 500
pc) and analyse these observations in combination with archival lower frequency
radio and mid-infrared measurements. For the four regions for which the
observations support our models we find that the free-free component indeed
dominates the emission at 90 GHz, making up 76--90 per cent of the luminosity
at this frequency but with the data also consistent with all of the emission
being due to free-free. The estimates of free-free luminosities are also
consistent, within measurement and decomposition errors, with star-formation
rates derived from lower radio frequencies and mid-infrared observations. In
our analysis we consider both power-law and curved spectra for the synchrotron
component but do not find evidence to support the curved model in preference to
the power-law.Comment: 7 pages, 5 figures. Submitted to MNRAS. Further information, plots,
links to software are available at
http://www.mrao.cam.ac.uk/~bn204/galevol/2012-90ghz-m66.htm
Small Platforms, High Return: The Need to Enhance Investment in Small Satellites for Focused Science, Career Development, and Improved Equity
In the next decade, there is an opportunity for very high return on
investment of relatively small budgets by elevating the priority of smallsat
funding in heliophysics. We've learned in the past decade that these missions
perform exceptionally well by traditional metrics, e.g., papers/year/\$M
(Spence et al. 2022 -- arXiv:2206.02968). It is also well established that
there is a "leaky pipeline" resulting in too little diversity in leadership
positions (see the National Academies Report at
https://www.nationalacademies.org/our-work/increasing-diversity-in-the-leadership-of-competed-space-missions).
Prioritizing smallsat funding would significantly increase the number of
opportunities for new leaders to learn -- a crucial patch for the pipeline and
an essential phase of career development. At present, however, there are far
more proposers than the available funding can support, leading to selection
ratios that can be as low as 6% -- in the bottom 0.5th percentile of selection
ratios across the history of ROSES. Prioritizing SmallSat funding and
substantially increasing that selection ratio are the fundamental
recommendations being made by this white paper.Comment: White paper submitted to the Decadal Survey for Solar and Space
Physics (Heliophysics) 2024-2033; 6 pages, 1 figur
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Use of Orthogonal Array Composite Designs to Study Lipid Accumulation in a Cell-Free System
The development of clean, sustainable alternative energy sources is increasingly important. One promising alternative to depleting fuel reserves is algae-based biodiesel fuel, which is both non-toxic and renewable. Despite the tremendous potential of algae-based biodiesel fuel, it has not yet been profitable because of the high cost per unit area of large cultivation. We present a novel application of Orthogonal Array Composite Designs (OACDs) to optimize lipid production of a cell-free system for algae. An OACD consists of a two-level fractional factorial design and a three-level orthogonal array. We start with an initial screening experiment based on six chemicals using an OACD with 50 runs. Based on this experiment, two chemical compounds were removed and a follow-up 25-run OACD with four chemicals was performed. Our analysis shows that only three chemicals – nitrogen, magnesium, and phosphate – are essential for lipid accumulation, and a range of optimum combinations of these three chemicals is identified. The lipid accumulation for these three chemical combinations is substantially higher in comparison to the commercial medium, which contains 16 chemicals and soil water. This leads to a reduced cost of the chemical medium and increased efficiency of biodiesel production from the algal-based cell-free system, which can be used to significantly expand the use of biodiesel as a viable alternative to fossil fuels. Copyright © 2015 John Wiley & Sons, Ltd
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Application of fractional factorial designs to study drug combinations.
Herpes simplex virus type 1 (HSV-1) is known to cause diseases of various severities. There is increasing interest to find drug combinations to treat HSV-1 by reducing drug resistance and cytotoxicity. Drug combinations offer potentially higher efficacy and lower individual drug dosage. In this paper, we report a new application of fractional factorial designs to investigate a biological system with HSV-1 and six antiviral drugs, namely, interferon alpha, interferon beta, interferon gamma, ribavirin, acyclovir, and tumor necrosis factor alpha. We show how the sequential use of two-level and three-level fractional factorial designs can screen for important drugs and drug interactions, as well as determine potential optimal drug dosages through the use of contour plots. Our initial experiment using a two-level fractional factorial design suggests that there is model inadequacy and that drug dosages should be reduced. A follow-up experiment using a blocked three-level fractional factorial design indicates that tumor necrosis factor alpha has little effect and that HSV-1 infection can be suppressed effectively by using the right combination of the other five antiviral drugs. These observations have practical implications in the understanding of antiviral drug mechanism that can result in better design of antiviral drug therapy
Biosemiotic Entropy: Concluding the Series
This article concludes the special issue on Biosemiotic Entropy looking toward the future on the basis of current and prior results. It highlights certain aspects of the series, concerning factors that damage and degenerate biosignaling systems. As in ordinary linguistic discourse, well-formedness (coherence) in biological signaling systems depends on valid representations correctly construed: a series of proofs are presented and generalized to all meaningful sign systems. The proofs show why infants must (as empirical evidence shows they do) proceed through a strict sequence of formal steps in acquiring any language. Classical and contemporary conceptions of entropy and information are deployed showing why factors that interfere with coherence in biological signaling systems are necessary and sufficient causes of disorders, diseases, and mortality. Known sources of such formal degeneracy in living organisms (here termed, biosemiotic entropy) include: (a) toxicants, (b) pathogens; (c) excessive exposures to radiant energy and/or sufficiently powerful electromagnetic fields; (d) traumatic injuries; and (e) interactions between the foregoing factors. Just as Jaynes proved that irreversible changes invariably increase entropy, the theory of true narrative representations (TNR theory) demonstrates that factors disrupting the well-formedness (coherence) of valid representations, all else being held equal, must increase biosemiotic entropy—the kind impacting biosignaling systems
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