Reducing Mowing Requirements in Home Lawn and Golf Course Turfgrass

Turfgrass systems are routinely managed by frequent mowing to increase aesthetics and function. Mowing is resource intensive with a high labor and energy demand. Reducing the number of mowings events in a growing season will decrease the labor and energy but may reduce quality as well. Previous work has looked at reducing mowing by changing the frequency and by using a plant growth regulator (PGR). Limited information is available about how to reduce mowing while maintaining acceptable quality. We looked at two different management practices to reduce mowing and maintain quality. The first study evaluated seven different mowing frequencies at two mowing heights (7.6 cm and 5.1 cm). Dry clipping yield mass was measured and the total number of mowing events were recorded from the different treatments. Weekly visual quality ratings were recorded using the NTEP scale. Removing one-third of the leaf biomass at mowing minimized mowing requirements while it sustained turfgrass quality rating. Mowing more frequently increased further improved turfgrass quality. The second study examined lengthening the longevity of suppression from two PGRs by the inclusion of various surfactants with the application Clipping suppression was modeled with sine wave regression to determine the suppression of both PGRs and for comparison of clipping yield suppression provided by the PGR applied alone. Visual quality declined in with the straight block co-polymer surfactant. Advisor: William C. Kreuse

The Correlations between Teacher Assessment of Second Graders’ Reading Abilities and Their Performance on Subtests of the Test of Cognitive Skills

The purpose of this study was to determine the relationships between teacher assessment of students\u27 reading abilities and the students\u27 performance on the subtests of the Test of Cognitive Skills – Second Edition - Level 1. The need for the study was prompted by the movement of districts to utilize more authentic means of assessing reading ability and explore their consequent validity. It was also to determine if teachers are focusing in a particular cognitive domain when assessing the reading abilities of their students. Fifty-five heterogeneously grouped third grade students who attend an intermediate school in a western New York suburb served as the subjects of the study. Degrees of Reading Power (DRP) levels, identified by second grade teachers using running reading records, were compared with Test of Cognitive Skills – Second Edition - Level (TCS/2 - Level 1) subtest scores. The data were then analyzed using the Pearson product moment correlation to determine if any strong relationships (r ≥ .5000) existed between the assigned DRP levels and the subtests of sequences, memory, analogies, and verbal reasoning. After the data were analyzed, it was found that a strong correlation (r = .5193) existed between the DRP levels, which ultimately represented higher achieving readers, and scores on the verbal reasoning subtest of the Test of Cognitive Skills - Second Edition – Level 1. This correlation was also found to be significant at the .001 level

Combustion and operating characteristics of spark-ignition engines

The spark-ignition engine turbulent flame propagation process was investigated. Then, using a spark-ignition engine cycle simulation and combustion model, the impact of turbocharging and heat transfer variations or engine power, efficiency, and NO sub x emissions was examined

Topological bands in two-dimensional networks of metamaterial elements

We show that topological frequency band structures emerge in two-dimensional electromagnetic lattices of metamaterial components without the application of an external magnetic field. The topological nature of the band structure manifests itself by the occurrence of exceptional points in the band structure or by the emergence of one-way guided modes. Based on an EM network with nearly flat frequency bands of nontrivial topology, we propose a coupled-cavity lattice made of superconducting transmission lines and cavity QED components which is described by the Janes-Cummings-Hubbard model and can serve as simulator of the fractional quantum Hall effect

A Suzaku, NuSTAR, and XMM-Newton view on variable absorption and relativistic reflection in NGC 4151

We disentangle X-ray disk reflection from complex line-of-sight absorption in the nearby Seyfert NGC 4151, using a suite of Suzaku, NuSTAR, and XMM-Newton observations. Extending upon earlier published work, we pursue a physically motivated model using the latest angle-resolved version of the lamp-post geometry reflection model relxillCp_lp together with a Comptonization continuum. We use the long-look simultaneous Suzaku/NuSTAR observation to develop a baseline model wherein we model reflected emission as a combination of lamp-post components at the heights of 1.2 and 15.0 gravitational radii. We argue for a vertically extended corona as opposed to two compact and distinct primary sources. We find two neutral absorbers (one full-covering and one partial-covering), an ionized absorber ($\log \xi = 2.8$), and a highly-ionized ultra-fast outflow, which have all been reported previously. All analyzed spectra are well described by this baseline model. The bulk of the spectral variability between 1 keV and 6 keV can be accounted for by changes in the column density of both neutral absorbers, which appear to be degenerate and inversely correlated with the variable hard continuum component flux. We track variability in absorption on both short (2 d) and long ($\sim$1 yr) timescales; the observed evolution is either consistent with changes in the absorber structure (clumpy absorber at distances ranging from the broad line region (BLR) to the inner torus or a dusty radiatively driven wind) or a geometrically stable neutral absorber that becomes increasingly ionized at a rising flux level. The soft X-rays below 1 keV are dominated by photoionized emission from extended gas that may act as a warm mirror for the nuclear radiation.Comment: 21 pages, 19 figures, 8 tables, accepted for publication by A&

On Estimating the High-Energy Cutoff in the X-ray Spectra of Black Holes via Reflection Spectroscopy

The fundamental parameters describing the coronal spectrum of an accreting black hole are the slope $\Gamma$ of the power-law continuum and the energy $E_{cut}$ at which it rolls over. Remarkably, this parameter can be accurately measured for values as high as 1 MeV by modeling the spectrum of X-rays reflected from a black hole accretion disk at energies below 100 keV. This is possible because the details in the reflection spectrum, rich in fluorescent lines and other atomic features, are very sensitive to the spectral shape of the hardest coronal radiation illuminating the disk. We show that fitting simultaneous NuSTAR (3-79 keV) and low-energy (e.g., Suzaku) data with the most recent version of our reflection model RELXILL, one can obtain reasonable constraints on $E_{cut}$ at energies from tens of keV up to 1 MeV, for a source as faint as 1 mCrab in a 100 ks observation.Comment: Accepted for publication in ApJL, 6 pages, 5 figure