Hamiltonian Dynamics of Yang-Mills Fields on a Lattice

We review recent results from studies of the dynamics of classical Yang-Mills fields on a lattice. We discuss the numerical techniques employed in solving the classical lattice Yang-Mills equations in real time, and present results exhibiting the universal chaotic behavior of nonabelian gauge theories. The complete spectrum of Lyapunov exponents is determined for the gauge group SU(2). We survey results obtained for the SU(3) gauge theory and other nonlinear field theories. We also discuss the relevance of these results to the problem of thermalization in gauge theories.Comment: REVTeX, 51 pages, 20 figure

Exploring molecular complexity with ALMA (EMoCA): Detection of three new hot cores in Sagittarius B2(N)

The SgrB2 molecular cloud contains several sites forming high-mass stars. SgrB2(N) is one of its main centers of activity. It hosts several compact and UCHII regions, as well as two known hot molecular cores (SgrB2(N1) and SgrB2(N2)), where complex organic molecules are detected. Our goal is to use the high sensitivity of ALMA to characterize the hot core population in SgrB2(N) and shed a new light on the star formation process. We use a complete 3 mm spectral line survey conducted with ALMA to search for faint hot cores in SgrB2(N). We report the discovery of three new hot cores that we call SgrB2(N3), SgrB2(N4), and SgrB2(N5). The three sources are associated with class II methanol masers, well known tracers of high-mass star formation, and SgrB2(N5) also with a UCHII region. The chemical composition of the sources and the column densities are derived by modelling the whole spectra under the assumption of LTE. The H2 column densities are computed from ALMA and SMA continuum emission maps. The H2 column densities of these new hot cores are found to be 16 up to 36 times lower than the one of the main hot core Sgr B2(N1). Their spectra have spectral line densities of 11 up to 31 emission lines per GHz, assigned to 22-25 molecules. We derive rotational temperatures around 140-180 K for the three new hot cores and mean source sizes of 0.4 for SgrB2(N3) and 1.0 for SgrB2(N4) and SgrB2(N5). SgrB2(N3) and SgrB2(N5) show high velocity wing emission in typical outflow tracers, with a bipolar morphology in their integrated intensity maps suggesting the presence of an outflow, like in SgrB2(N1). The associations of the hot cores with class II methanol masers, outflows, and/or UCHII regions tentatively suggest the following age sequence: SgrB2(N4), SgrB2(N3), SgrB2(N5), SgrB2(N1). The status of SgrB2(N2) is unclear. It may contain two distinct sources, a UCHII region and a very young hot core.Comment: Accepted for publication in A&A, 24 pages, 23 figure

Nonperturbative Effects in Quarkonia Associated with Large Orders in Perturbation Theory

We show that the perturbation series for quarkonia energies diverges at large orders. This results in a perturbative ambiguity in the energy that scales as e^(-1/a*Lambda) where a is the Bohr radius of quarkonium and Lambda is the QCD scale parameter. This ambiguity is associated with a nonperturbative contribution to the energy from distances of order 1/Lambda and greater. This contribution is separate from that of the gluon condensate.Comment: 6 pages, 2 figure

Soybean Planting Dates in Northeast Iowa

Soybean planting date studies of various types have been conducted at this site since 1976. Earlier tests included later planting dates (May through mid-June), differing variety maturities, and comparisons with starter fertilizer and Ridomil fungicide soil treatments. Research reports on these studies can be found in previous annual progress reports with the last summary in the 2001 and 2009 reports

Effect of Fungicides and Plant Populations on Soybean Disease and Yield

Fungicides on soybeans provide growers an effective management strategy for foliar diseases, especially soybean rust. However, many questions about fungicides and how common practices affect fungicide efficacy are still unresolved. One possible cultural practice that may affect fungicide efficacy is plant population. Higher plant populations may provide a more conducive microenvironment for certain plant diseases and may reduce the penetration of fungicides to the lower canopy. The objective of these studies was to evaluate the efficacy of fungicides in different soybean plant populations