740 research outputs found
Processing PSE and DFD pork
1 online resource (PDF, 4 pages)This archival publication may not reflect current scientific knowledge or recommendations. Current information available from the University of Minnesota Extension: https://www.extension.umn.edu
Thermodynamically Important Contacts in Folding of Model Proteins
We introduce a quantity, the entropic susceptibility, that measures the
thermodynamic importance-for the folding transition-of the contacts between
amino acids in model proteins. Using this quantity, we find that only one
equilibrium run of a computer simulation of a model protein is sufficient to
select a subset of contacts that give rise to the peak in the specific heat
observed at the folding transition. To illustrate the method, we identify
thermodynamically important contacts in a model 46-mer. We show that only about
50% of all contacts present in the protein native state are responsible for the
sharp peak in the specific heat at the folding transition temperature, while
the remaining 50% of contacts do not affect the specific heat.Comment: 5 pages, 5 figures; to be published in PR
Corrigendum to “Effects of therapeutic hypothermia on the gut microbiota and metabolome of infants suffering hypoxic-ischemic encephalopathy at birth” [Int. J. Biochem. Cell Biol. 93 (December) (2017), 110-118]
peer-reviewedCorrigendum Refers to:
Watkins, C., Murphy, K., Yen, S., Carafa, I., Dempsey, E., O’Shea, C., Vercoe, E., Ross, R., Stanton, C. and Ryan, C. (2017). Effects of therapeutic hypothermia on the gut microbiota and metabolome of infants suffering hypoxic-ischemic encephalopathy at birth. The International Journal of Biochemistry & Cell Biology, [online] 93, pp.110-118. Available at: https://doi.org/10.1016/j.biocel.2017.08.01
Optimality of mutation and selection in germinal centers
The population dynamics theory of B cells in a typical germinal center could
play an important role in revealing how affinity maturation is achieved.
However, the existing models encountered some conflicts with experiments. To
resolve these conflicts, we present a coarse-grained model to calculate the B
cell population development in affinity maturation, which allows a
comprehensive analysis of its parameter space to look for optimal values of
mutation rate, selection strength, and initial antibody-antigen binding level
that maximize the affinity improvement. With these optimized parameters, the
model is compatible with the experimental observations such as the ~100-fold
affinity improvements, the number of mutations, the hypermutation rate, and the
"all or none" phenomenon. Moreover, we study the reasons behind the optimal
parameters. The optimal mutation rate, in agreement with the hypermutation rate
in vivo, results from a tradeoff between accumulating enough beneficial
mutations and avoiding too many deleterious or lethal mutations. The optimal
selection strength evolves as a balance between the need for affinity
improvement and the requirement to pass the population bottleneck. These
findings point to the conclusion that germinal centers have been optimized by
evolution to generate strong affinity antibodies effectively and rapidly. In
addition, we study the enhancement of affinity improvement due to B cell
migration between germinal centers. These results could enhance our
understandings to the functions of germinal centers.Comment: 5 figures in main text, and 4 figures in Supplementary Informatio
Dispersity-Driven Melting Transition in Two Dimensional Solids
We perform extensive simulations of Lennard-Jones particles to study
the effect of particle size dispersity on the thermodynamic stability of
two-dimensional solids. We find a novel phase diagram in the dispersity-density
parameter space. We observe that for large values of the density there is a
threshold value of the size dispersity above which the solid melts to a liquid
along a line of first order phase transitions. For smaller values of density,
our results are consistent with the presence of an intermediate hexatic phase.
Further, these findings support the possibility of a multicritical point in the
dispersity-density parameter space.Comment: In revtex format, 4 pages, 6 postscript figures. Submitted to PR
Liquid State Anomalies for the Stell-Hemmer Core-Softened Potential
We study the Stell-Hemmer potential using both analytic (exact and
approximate ) solutions and numerical simulations. We observe in the
liquid phase an anomalous decrease in specific volume and isothermal
compressibility upon heating, and an anomalous increase in the diffusion
coefficient with pressure. We relate the anomalies to the existence of two
different local structures in the liquid phase. Our results are consistent with
the possibility of a low temperature/high pressure liquid-liquid phase
transition.Comment: 4 pages in one gzipped ps file including 11 figures; One RevTex and
11 gzipped eps figure
A life in progress: motion and emotion in the autobiography of Robert M. La Follette
This article is a study of a La Follette’s Autobiography, the autobiography of the leading Wisconsin progressive Robert M. La Follette, which was published serially in 1911 and, in book form, in 1913. Rather than focusing, as have other historians, on which parts of La Follette’s account are accurate and can therefore be trusted, it explains instead why and how this major autobiography was conceived and written. The article shows that the autobiography was the product of a sustained, complex, and often fraught series of collaborations among La Follette’s family, friends, and political allies, and in the process illuminates the importance of affective ties as well as political ambition and commitment in bringing the project to fruition. In the world of progressive reform, it argues, personal and political experiences were inseparable
Prospecting in ultracool dwarfs : Measuring the metallicities of mid- and late-m dwarfs
© 2014. The American Astronomical Society. All rights reserved.Metallicity is a fundamental parameter that contributes to the physical characteristics of a star. The low temperatures and complex molecules present in M dwarf atmospheres make it difficult to measure their metallicities using techniques that have been commonly used for Sun-like stars. Although there has been significant progress in developing empirical methods to measure M dwarf metallicities over the last few years, these techniques have been developed primarily for early- to mid-M dwarfs. We present a method to measure the metallicity of mid- to late-M dwarfs from moderate resolution (R ∼ 2000) K-band (≃ 2.2 μm) spectra. We calibrate our formula using 44 wide binaries containing an F, G, K, or early-M primary of known metallicity and a mid- to late-M dwarf companion. We show that similar features and techniques used for early-M dwarfs are still effective for late-M dwarfs. Our revised calibration is accurate to ∼0.07 dex for M4.5-M9.5 dwarfs with -0.58 <[Fe/H] <+0.56 and shows no systematic trends with spectral type, metallicity, or the method used to determine the primary star metallicity. We show that our method gives consistent metallicities for the components of M+M wide binaries. We verify that our new formula works for unresolved binaries by combining spectra of single stars. Lastly, we show that our calibration gives consistent metallicities with the Mann et al. study for overlapping (M4-M5) stars, establishing that the two calibrations can be used in combination to determine metallicities across the entire M dwarf sequence.Peer reviewe
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