186 research outputs found
Chapter 01 - The History of Early Materials
This chapter explores some of the earliest writing materials and systems with a particular focus on the use of clay tablets, papyrus, bamboo, and silk.https://digitalcommons.wou.edu/history_of_book/1000/thumbnail.jp
Quantification of Aspartame in Diet Sodas
Aspartame is an artificial sweetener much like high fructose corn syrup but is synthetically made compared to being derived from a naturally occurring compound. Many diet beverages and foods contain this chemical since it is about 200 times sweeter than regular table sugar and contains very few calories. Some people with a hereditary disease cannot metabolize the phenylalanine resulting from the breakdown of the aspartame. This, and potential health risks, have caused widespread controversy regarding the FDA approval of aspartame. I have used High Performance Liquid Chromatography (HPLC) to quantify the amount of aspartame present in Diet Coke and Diet Pepper. I investigated how elevated temperatures can cause aspartame to become unstable and breakdown into potentially toxic chemicals. These findings will promote the labeling of actual amounts present in each drink, similar to how caffeine is labeled
Exploring the Properties of Mira-Type Stars with Spectropolarimetry.
Mira-type stars are luminous red giants that have pulsation periods that last anywhere between 100 and 700 days. The irregular behavior of their periods and atmospheric properties flag them as excellent candidates for astrophysical studies of non-spherical stars. This paper focuses on the linear polarization of light emitted from three Mira- type stars: Mira itself, R Leo, and V CVn. Polarimetric data from the University of Wisconsin’s Half-Wave Spectropolarimeter (HPOL) database, as well as other archives of polarimetric data, provide us with insight into the atmospheric and geometrical prop- erties of these three stars. We were able to study the net polarizations and position angles alongside light curves provided by AAVSO. The observed variable polarization is a clear signature of evolving aspherical geometries for these stars. However, we found a major surprise concerning the polarimetric characteristics in V CVn, which suggest that V CVn is unlike a traditional Mira-type variable star. We end with an exploration of new possibilities regarding the atmospheric properties of V CVn
Formal Definitions of Unbounded Evolution and Innovation Reveal Universal Mechanisms for Open-Ended Evolution in Dynamical Systems
Open-ended evolution (OEE) is relevant to a variety of biological, artificial
and technological systems, but has been challenging to reproduce in silico.
Most theoretical efforts focus on key aspects of open-ended evolution as it
appears in biology. We recast the problem as a more general one in dynamical
systems theory, providing simple criteria for open-ended evolution based on two
hallmark features: unbounded evolution and innovation. We define unbounded
evolution as patterns that are non-repeating within the expected Poincare
recurrence time of an equivalent isolated system, and innovation as
trajectories not observed in isolated systems. As a case study, we implement
novel variants of cellular automata (CA) in which the update rules are allowed
to vary with time in three alternative ways. Each is capable of generating
conditions for open-ended evolution, but vary in their ability to do so. We
find that state-dependent dynamics, widely regarded as a hallmark of life,
statistically out-performs other candidate mechanisms, and is the only
mechanism to produce open-ended evolution in a scalable manner, essential to
the notion of ongoing evolution. This analysis suggests a new framework for
unifying mechanisms for generating OEE with features distinctive to life and
its artifacts, with broad applicability to biological and artificial systems.Comment: Main document: 17 pages, Supplement: 21 pages Presented at OEE2: The
Second Workshop on Open-Ended Evolution, 15th International Conference on the
Synthesis and Simulation of Living Systems (ALIFE XV), Canc\'un, Mexico, 4-8
July 2016 (http://www.tim-taylor.com/oee2/
Evidence of a Mira-like tail and bow shock about the semi-regular variable V CVn from four decades of polarization measurements
Polarization is a powerful tool for understanding stellar atmospheres and
circumstellar environments. Mira and semi-regular variable stars have been
observed for decades and some are known to be polarimetrically variable,
however, the semi-regular variable V Canes Venatici displays an unusually
large, unexplained amount of polarization. We present ten years of optical
polarization observations obtained with the HPOL instrument, supplemented by
published observations spanning a total interval of about forty years for V
CVn. We find that V CVn shows large polarization variations ranging from 1 -
6%. We also find that for the past forty years the position angle measured for
V CVn has been virtually constant suggesting a long-term, stable, asymmetric
structure about the star. We suggest that this asymmetry is caused by the
presence of a stellar wind bow shock and tail, consistent with the star's large
space velocity.Comment: 8 pages, 5 figures, 1 table. Accepted for publication in A&
Optimal Spatial Deconvolution and Message Reconstruction from a Large Generative Model of Models
We introduce a general-purpose univariate signal deconvolution method based
on the principles of an approach to Artificial General Intelligence. This
approach is based on a generative model that combines information theory and
algorithmic probability that required a large calculation of an estimation of a
`universal distribution' to build a general-purpose model of models independent
of probability distributions. This was used to investigate how non-random data
may encode information about the physical properties such as dimension and
length scales in which a signal or message may have been originally encoded,
embedded, or generated. This multidimensional space reconstruction method is
based on information theory and algorithmic probability, and it is agnostic,
but not independent, with respect to the chosen computable or semi-computable
approximation method or encoding-decoding scheme. The results presented in this
paper are useful for applications in coding theory, particularly in
zero-knowledge one-way communication channels, such as in deciphering messages
sent by generating sources of unknown nature for which no prior knowledge is
available. We argue that this can have strong potential for cryptography,
signal processing, causal deconvolution, life, and techno signature detection.Comment: 35 page
Senescent mouse cells fail to overtly regulate the HIRA histone chaperone and do not form robust Senescence Associated Heterochromatin Foci
<p>Abstract</p> <p>Background</p> <p>Cellular senescence is a permanent growth arrest that occurs in response to cellular stressors, such as telomere shortening or activation of oncogenes. Although the process of senescence growth arrest is somewhat conserved between mouse and human cells, there are some critical differences in the molecular pathways of senescence between these two species. Recent studies in human fibroblasts have defined a cell signaling pathway that is initiated by repression of a specific Wnt ligand, Wnt2. This, in turn, activates a histone chaperone HIRA, and culminates in formation of specialized punctate domains of facultative heterochromatin, called Senescence-Associated Heterochromatin Foci (SAHF), that are enriched in the histone variant, macroH2A. SAHF are thought to repress expression of proliferation-promoting genes, thereby contributing to senescence-associated proliferation arrest. We asked whether this Wnt2-HIRA-SAHF pathway is conserved in mouse fibroblasts.</p> <p>Results</p> <p>We show that mouse embryo fibroblasts (MEFs) and mouse skin fibroblasts, do not form robust punctate SAHF in response to an activated Ras oncogene or shortened telomeres. However, senescent MEFs do exhibit elevated levels of macroH2A staining throughout the nucleus as a whole. Consistent with their failure to fully activate the SAHF assembly pathway, the Wnt2-HIRA signaling axis is not overtly regulated between proliferating and senescent mouse cells.</p> <p>Conclusions</p> <p>In addition to the previously defined differences between mouse and human cells in the mechanisms and phenotypes associated with senescence, we conclude that senescent mouse and human fibroblasts also differ at the level of chromatin and the signaling pathways used to regulate chromatin. These differences between human and mouse senescence may contribute to the increased propensity of mouse fibroblasts (and perhaps other mouse cell types) to become immortalized and transformed, compared to human cells.</p
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