IMPACT OF PREEMERGENT HERBICIDES, MOWING HEIGHT, AND FERTILIZATION ON CENTIPEDEGRASS ROOT ARCHITECTURE AND DROUGHT TOLERANCE

Mowing, N fertilization and the application of preemergence herbicides (PRE) are cultural practices performed on centipedegrass to improve overall turf quality. It is posited that increasing mowing height and application of fertilizers can lead to greater turfgrass rooting and increase drought survival; while the application of PRE is reported to potentially have negative impacts on rooting. At two locations in Louisiana, studies examining the effects of these practices on centipedegrass rooting and drought tolerance were conducted. In the first 11-week study conducted, centipedegrass was treated with dithiopyr, pendimethalin, prodiamine, simazine, or indaziflam at the manufacturers’ labeled rates. During the 11-wk experiments, roots were harvested at upper and lower contiguous soil depths of 7.5 cm and analyzed for root length (RL), surface area (SA), average diameter (AD), length volume-1 (LPV), and root mass (RM). Across all treatments and soil depths, PRE did not alter rooting compared to controls with the exception of AD for simazine-treated centipedegrass at 0.397 mm compared to 0.338 and 0.341mm for prodiamine and indaziflam, respectively. At 11 wks., cores were harvested and subjected to a 28 d dry-down period. Centipedegrass maintained acceptable leaf color for 13 days before complete leaf firing occurred at 20 days. A single application of PRE to mature centipedegrass during early spring did not alter rooting or drought tolerance compared to controls. In the second study, centipedegrass was maintained at one of four mowing heights (2.5, 5, 7.5 and 10 cm) and subjected to fertilization or no fertilization. During the 29-wk experiments, roots were harvested and analyzed as above and subjected to a mid-summer 36-day drought simulation. All centipedegrass in these experiments exhibited a pattern of increased leaf firing over the drought simulation with unfertilized centipedegrass maintaining acceptable leaf color (≥5) for 19 days at 5.9 compared to 4.8 when fertilized. Rooting parameter measurements across all mowing heights and soil depths initially declined from spring into summer then increased in fall. This, in conjunction with the lack of changes in rooting from alterations in cultural practices, indicates soil temperature may be a significant factor in centipedegrass rooting

The Golf Caddie - The Forgotten Worker

Caddies are an integral part of the game of golf. As an occupation, little is known regarding the physical and psychological demands of caddying. Likewise, there is a dearth of scientific literature regarding musculoskeletal disorders (MSDs) among caddies. This research endeavor attempted to provide a review of literature regarding the physical demands associated with caddying as well as the prevalence of MSDs. The authors then provide targeted research recommendations to address the shortcomings of the current state of the scientific literature as related to the occupation of caddying. This information may help inform workplace health intervention strategies to improve job performance/satisfaction, lower the occurrence of MSDs, lower health care costs, increase occupational longevity, and enhance the quality of life for the professional caddie

Dynamics of laterally-coupled pairs of spin-VCSELs

A newly-developed normal mode model of laser dynamics in a generalised array of waveguides is applied to extend the spin-flip model (SFM) to pairs of evanescently-coupled spin-VCSELS. The effect of high birefringence is explored, revealing new dynamics and regions of bistability. It is shown that optical switching of the polarisation states of the lasers may be controlled through the optical pump and that, under certain conditions, the polarisation of one laser may be switched by controlling the intensity and polarisation in the other

Migration of Extrasolar Planets: Effects from X-Wind Accretion Disks

Magnetic fields are dragged in from the interstellar medium during the gravitational collapse that forms star/disk systems. Consideration of mean field magnetohydrodynamics (MHD) in these disks shows that magnetic effects produce subkeplerian rotation curves and truncate the inner disk. This letter explores the ramifications of these predicted disk properties for the migration of extrasolar planets. Subkeplerian flow in gaseous disks drives a new migration mechanism for embedded planets and modifies the gap opening processes for larger planets. This subkeplerian migration mechanism dominates over Type I migration for sufficiently small planets (m_P < 1 M_\earth) and/or close orbits (r < 1 AU). Although the inclusion of subkeplerian torques shortens the total migration time by only a moderate amount, the mass accreted by migrating planetary cores is significantly reduced. Truncation of the inner disk edge (for typical system parameters) naturally explains final planetary orbits with periods P=4 days. Planets with shorter periods P=2 days can be explained by migration during FU-Ori outbursts, when the mass accretion rate is high and the disk edge moves inward. Finally, the midplane density is greatly increased at the inner truncation point of the disk (the X-point); this enhancement, in conjunction with continuing flow of gas and solids through the region, supports the in situ formation of giant planets.Comment: 15 pages, 2 figures, accepted to ApJ Letter

Stability of Magnetized Disks and Implications for Planet Formation

This paper considers gravitational perturbations in geometrically thin disks with rotation curves dominated by a central object, but with substantial contributions from magnetic pressure and tension. The treatment is general, but the application is to the circumstellar disks that arise during the gravitational collapse phase of star formation. We find the dispersion relation for spiral density waves in these generalized disks and derive the stability criterion for axisymmetric $(m=0)$ disturbances (the analog of the Toomre parameter $Q_T$) for any radial distribution of the mass-to-flux ratio $\lambda$. The magnetic effects work in two opposing directions: on one hand, magnetic tension and pressure stabilize the disk against gravitational collapse and fragmentation; on the other hand, they also lower the rotation rate making the disk more unstable. For disks around young stars the first effect generally dominates, so that magnetic fields allow disks to be stable for higher surface densities and larger total masses. These results indicate that magnetic fields act to suppress the formation of giant planets through gravitational instability. Finally, even if gravitational instability can form a secondary body, it must lose an enormous amount of magnetic flux in order to become a planet; this latter requirement represents an additional constraint for planet formation via gravitational instability and places a lower limit on the electrical resistivity.Comment: accepted in Ap

Innovating Pedagogy 2015: Open University Innovation Report 4

This series of reports explores new forms of teaching, learning and assessment for an interactive world, to guide teachers and policy makers in productive innovation. This fourth report proposes ten innovations that are already in currency but have not yet had a profound influence on education. To produce it, a group of academics at the Institute of Educational Technology in The Open University collaborated with researchers from the Center for Technology in Learning at SRI International. We proposed a long list of new educational terms, theories, and practices. We then pared these down to ten that have the potential to provoke major shifts in educational practice, particularly in post-school education. Lastly, we drew on published and unpublished writings to compile the ten sketches of new pedagogies that might transform education. These are summarised below in an approximate order of immediacy and timescale to widespread implementation

Shielding Calculations on Waste Packages – The Limits and Possibilities of different Calculation Methods by the example of homogeneous and inhomogeneous Waste Packages

For nuclear waste packages the expected dose rates and nuclide inventory are beforehand calculated. Depending on the package of the nuclear waste deterministic programs like MicroShield® provide a range of results for each type of packaging. Stochastic programs like “Monte-Carlo N-Particle Transport Code System” (MCNP®) on the other hand provide reliable results for complex geometries. However this type of program requires a fully trained operator and calculations are time consuming. The problem here is to choose an appropriate program for a specific geometry. Therefore we compared the results of deterministic programs like MicroShield® and stochastic programs like MCNP®. These comparisons enable us to make a statement about the applicability of the various programs for chosen types of containers. As a conclusion we found that for thin-walled geometries deterministic programs like MicroShield® are well suited to calculate the dose rate. For cylindrical containers with inner shielding however, deterministic programs hit their limits. Furthermore we investigate the effect of an inhomogeneous material and activity distribution on the results. The calculations are still ongoing. Results will be presented in the final abstract

Masters Athletes: No Evidence of Increased Incidence of Injury in Football Code Athletes

The World Masters Games, held quadrennially, is the largest international sporting competition in terms of participant numbers. Yet this cohort remains proportionately under investigated. An online survey using an open-source specialized survey application software program was utilized to investigate the 2009 Sydney World Masters Games (SWMG) football code athletes (association football, touch football, rugby union). A total of 931 masters athletes (28.2% response rate, aged 29 - 72 yrs, mean = 47.6, SD ± 7.1, 52.5% male) completed the survey, with touch football reporting the highest incidence of injury (29.2%) followed by rugby (27.0%) and soccer (21.2%). Analyzing injury data (t-tests, chi square) identified patterns in injury location (legs (11.2%, p \u3c 0.01) followed by knees, feet and ankles) and significant (p \u3c 0.01) classification patterns (muscle/tendon strain/tear (13.0%, p \u3c 0.05), inflammation (6.1%), joint pain (6.0%) and ligament sprain/tear (5.8%)). There were also significant differences (p \u3c 0.01) compared to general and elite sporting population data. For masters football athletes at the SWMG, the injury incidence during preparation for the tournament has similarities to, but is in fact significantly less than for these other sporting populations. Some gender and sport based differences in injury location and classification type were identified. There were also no significant age related changes in injury nature (classification type, location, incidence, time off work or training). Therefore these findings do not support the premise of masters football code athletes having a higher incidence of injury as compared to younger athletes