Soil compaction and over-winter changes to tracked-vehicle ruts, Yakima Training Center, Washington

We monitored two experimental areas at the Yakima Training Center (YTC) in central Washington to measure changes to M1A2 Abrams (M1) tank-rut surface geometry and in- and out-of-rut saturated hydraulic conductivity (K_fs), soil penetration resistance (SPR) and soil bulk density (BD). Profile-meter data show that rut cross-sectional profiles smoothed significantly and that turning ruts did so more than straight ruts. Rut edges were zones of erosion and sidewall bases were zones of deposition. K_fs values were similar in and out of ruts formed on soil with 0–5% moisture by volume, but were lower in ruts formed on soil with about 15% water. Mean SPR was similar in and out of ruts from 0- to 5-cm depth, increased to 2 MPa outside ruts and 4 MPa inside ruts at 10- to 15-cm depth, and decreased by 10–38% outside ruts and by 39–48% inside ruts at the 30-cm depth. Soil BD was similar in and out of ruts from 0- to 2.5-cm depth, and below 2.5 cm, it was generally higher in ruts formed on moist soil with highest values between 10- and 20-cm depth. Conversely, BD in ruts formed on dry soil was similar to out-of-rut BD at all depths. This information is important for determining impacts of tank ruts on water infiltration and soil erosion and for modifying the Revised Universal Soil Loss Equation (RUSLE) and the Water Erosion Prediction Project (WEPP) models to more accurately predict soil losses on army training lands.     

On the optimality of the logistic growth

The rate at which a population should grow is determined by finding the best trade-off between the loss due to the deviation from a target population size and the loss associated to the growing effort. It is also shown that, in the case of infinite-time horizon and quadratic loss functions, the optimal growth is logistic. This research was supported by the Centro Teoria dei Sistemi, CNR, and by the Italian Ministry of Public Education.     

Calorimetric experiments and two photon collisions

The energy pattern of two-photon collisions is calculated. Both two- and three-jet final states are included. Corrections from colour confinement can be computed in a simple way. Possible ways to suppress the two-photon background in calorimetric experiments on e⁺e^? annihilation into hadrons are also discussed.     

Meson hyperfine splittings and leptonic decays

The ³S-¹S mass separations of the bound quark-antiquark systems, as arising from one-gluon exchange, in the charm color quartet scheme, are discussed for the ground mesons and their first radial excitations expecially in connection to leptonic decay rates. Overall consistency requires large modifications for the positronium-like formulae for annihilation and the possible role in this direction of an outstanding gluon radiative correction to the leptonic width is pointed out.     

Calculation of the pseudoscalar masses from a QCD effective potential

We calculate the effective two-loop potential of QCD with massive quarks in the CJT composite operator formalism. To perform the wave-function renormalization of composite operators we are lead to a condition which corresponds to the Adler-Dashen requirement in the limit of vanishing quark masses. The condition also assures absence of spontaneous breaking of parity. Pseudoscalar masses are calculated from the second derivatives of the effective potential, and a fit is obtained for quark masses m_u = 3.6 MeV, m_d = 7 MeV, m_s = 152 MeV. We also comment on consistuent quark masses and on the effect of heavy quarks.     

Strong vacuum polarization and self-damping of e+e− annihilation

If the hadronic contribution to vacuum polarization, which is proportional to the ration of e⁺e^? annihilation into hadrons to that into μ⁺μ^? rises asymptotically as a power $\text{β >}\text{1}\text{2}$ of the squared four-momentum, the ratio $\text{σ}\text{(e}{}^{\mathrm{+}}\text{e}{}^{\mathrm{?}}\text{→hadrons)}\text{σ}$ point $\text{(}{}^{\mathrm{\sigma }}\text{point =}\text{(4πα}{}^2\text{)}\text{(3s))}$ is bound to be less than $\text{?}\text{(3}\text{tg}\text{πβ)}\text{(8α)}$ and this limit is approached sooner for higher β. Other models of vacuum polarizations are also considered together with their possible origin and implications.     

Analysis of the 1H NMR spectrum of α-tetralone

An analysis of both the aromatic and aliphatic portions of the ¹H NMR spectrum of α-tetralone has been carried out. Two deuterated derivatives, 2,2-dideuterio- and 4,4-dideuterio-α-tetralone, were prepared to facilitate unambiguous assignment of chemical shifts for the aliphatic protons. The conformation of the 6-membered alicyclic ring of the molecule is defined by the coupling constants among the aliphatic protons. Benzylic coupling was the only detectable long range interaction between the aliphatic and aromatic protons of the molecule. The magnitude and sign of these coupling constants agree with previous calculations of Wasylishen and Schaefer.