Kinetic Heterogeneities at Dynamical Crossovers

We perform molecular dynamics simulations of a model glass-forming liquid to measure the size of kinetic heterogeneities, using a dynamic susceptibility $\chi_{\rm ss}(a, t)$ that quantifies the number of particles whose dynamics are correlated on the length scale $a$ and time scale $t$. By measuring $\chi_{\rm ss}(a, t)$ as a function of both $a$ and $t$, we locate local maxima $\chi^\star$ at distances $a^\star$ and times $t^\star$. Near the dynamical glass transition, we find two types of maxima, both correlated with crossovers in the dynamical behavior: a smaller maximum corresponding to the crossover from ballistic to sub-diffusive motion, and a larger maximum corresponding to the crossover from sub-diffusive to diffusive motion. Our results indicate that kinetic heterogeneities are not necessarily signatures of an impending glass or jamming transition.Comment: 6 pages, 4 figure

Integrated On-Farm Decision Making: Economic Implications of Increased Variation in Litter Size

Increased litter sizes and associated piglet performance consequences, challenge swine producers. Stochastic modeling captured bioeconomic performance of individual piglets. As average litter size increased from 8.8 to 20.8 piglets, costs and revenues per head marketed from the demonstration herd decreased and total profit increased at a decreasing rate.stochastic modeling, farm business management, swine litter size, Agribusiness, Farm Management, Livestock Production/Industries,

Dynamical and quasistatic structural relaxation paths in Pd_(40)Ni_(40)P_(20) glass

By sequential heat treatment of a Pd_(40)Ni_(40)P_(20) metallic glass at temperatures and durations for which α-relaxation is not possible, dynamic, and quasistatic relaxation paths below the glass transition are identified via ex situ ultrasonic measurements following each heat treatment. The dynamic relaxation paths are associated with hopping between nonequilibrium potential energy states of the glass, while the quasistatic relaxation path is associated with reversible β-relaxation events toward quasiequilibrium states. These quasiequilibrium states are identified with secondary potential energy minima that exist within the inherent energy minimum of the glass, thereby supporting the concept of the sub-basin/metabasin organization of the potential-energy landscape

Following microscopic motion in a two dimensional glass-forming binary fluid

The dynamics of a binary mixture of large and small discs are studied at temperatures approaching the glass transition using an analysis based on the topology of the Voronoi polygon surrounding each atom. At higher temperatures we find that dynamics is dominated by fluid-like motion that involves particles entering and exiting the nearest-neighbour shells of nearby particles. As the temperature is lowered, the rate of topological moves decreases and motion becomes localised to regions of mixed pentagons and heptagons. In addition we find that in the low temperature state particles may translate significant distances without undergoing changes in their nearest neig hbour shell. These results have implications for dynamical heterogeneities in glass forming liquids.Comment: 12 pages, 7 figure

In vitro branched chain amino acid oxidation by porcine mammary tissue

Mammary secretory tissue from six (three each of parity 1 and 2) lactating sows (d 10 to 17 of lactation) was obtained via biopsy for in vitro incubation to determine CO2 production fr01TI individual branched chain amino acids. Carbon dioxide production levels as percentages of the 14C-labeled amino acid metabolized by the mammary tissue were 2.57, 1.86, and 4.07% for isoleucine, leucine, and valine, respectively (P\u3c .03). These results indicate that, in the lactating sow mammary gland, valine has the greatest oxidation rate of the branched chain amino acids.; Swine Day, Manhattan, KS, November 16, 199