Optical conductivity of alpha-Mn

The optical constants were measured at room temperature in the photon-energy range 0.6 to 6.5 eV on evaporated thin films. Evaporation conditions were chosen that gave the alpha-Mn crystal structure with reasonably large grains. The optical conductivity was separated into intraband and interband contributions by fitting to the Drude formula at low energies. The results are anomalous in comparison to other 3d transition metals. The free-electron lifetime is exceptionally sort (in agreement with the large dc resistivity of Mn), and the interband transitions seem unusually weak at the lower energies. Possible explanations related to the complicated crystal structure of alpha-Mn are discussed

Water yield, peak flow and high flow response of a large forested watershed in central Arkansas to sustained forest harvest operations

Environmental Scienc

Enhanced selectivity towards O2 and H2 dissociation on ultrathin Cu films on Ru(0001)

The following article appeared in Journal of Chemical Physics 137.7 (2012): 074706 and may be found at http://scitation.aip.org/content/aip/journal/jcp/137/7/10.1063/1.4746942The reactivity of Cu monolayer (ML) and bilayer films grown on Ru(0001) towards O2 and H2 has been investigated. O2 initial sticking coefficients were determined using the King and Wells method in the incident energy range 40-450 meV, and compared to the corresponding values measured on clean Ru(0001) and Cu(111) surfaces. A relative large O2 sticking coefficient (∼0.5-0.8) was measured for 1 ML Cu and even 2 ML Cu/Ru(0001). At low incident energies, this is one order of magnitude larger than the value observed on Cu(111). In contrast, the corresponding reactivity to H2 was near zero on both Cu monolayer and bilayer films, for incident energies up to 175 meV. Water adsorption on 2 ML Cu/Ru(0001) was found to behave quite differently than on the Ru(0001) and Cu(111) surfaces. Our study shows that Cu/Ru(0001) is a highly selective system, which presents a quite different chemical reactivity towards different species in the same range of collision energiesThe authors gratefully acknowledge the financial support by the Ministerio de Educación y Ciencia through projects CONSOLIDER-INGENIO 2010 on Molecular Nanoscience and FIS2007-61114 and Comunidad de Madrid through the program NANOMAGNET S-0505/MAT/0194. P.P. acknowledges support through the Marie Curie AMAROUT EU action and the Spanish MICINN “Juan de la Cierva” contrac

Velocity-selected molecular pulses produced by an electric guide

Electrostatic velocity filtering is a technique for the production of continuous guided beams of slow polar molecules from a thermal gas. We extended this technique to produce pulses of slow molecules with a narrow velocity distribution around a tunable velocity. The pulses are generated by sequentially switching the voltages on adjacent segments of an electric quadrupole guide synchronously with the molecules propagating at the desired velocity. This technique is demonstrated for deuterated ammonia (ND$_{3}$), delivering pulses with a velocity in the range of $20-100\,\rm{m/s}$ and a relative velocity spread of $(16\pm 2)\,$ at FWHM. At velocities around $60\,\rm{m/s}$, the pulses contain up to $10^6$ molecules each. The data are well reproduced by Monte-Carlo simulations, which provide useful insight into the mechanisms of velocity selection.Comment: 8 pages, 6 figure

Adiabatic orientation of rotating dipole molecules in an external field

The induced polarization of a beam of polar clusters or molecules passing through an electric or magnetic field region differs from the textbook Langevin-Debye susceptibility. This distinction, which is important for the interpretation of deflection and focusing experiments, arises because instead of acquiring thermal equilibrium in the field region, the beam ensemble typically enters the field adiabatically, i.e., with a previously fixed distribution of rotational states. We discuss the orientation of rigid symmetric-top systems with a body-fixed electric or magnetic dipole moment. The analytical expression for their "adiabatic-entry" orientation is elucidated and compared with exact numerical results for a range of parameters. The differences between the polarization of thermodynamic and "adiabatic-entry" ensembles, of prolate and oblate tops, and of symmetric-top and linear rotators are illustrated and identified.Comment: 18 pages, 4 figure

KINETIC ANALYSIS OF AGILITY LADDERS DRILLS AND THEIR COMPARISON TO SPORT-SPECIFIC MOVEMENTS SUCH AS SHUFFLING AND SPRINTING

This study assessed agility ladder drills for the purpose of comparing kinetic characteristics of these drills to one another, and to sprinting and shuffling. Subjects (N=30) performed six agility ladder drills as well as sprinted and shuffled to the left and right over two large force platforms. A repeated measure ANOVA was used to assess horizontal and vertical ground reaction force (GRF) and the ratio of horizontal to vertical GRF, averaged from three steps for each drill. Significant main effects were found for all variables (p ≤ 0.001). Post-hoc analysis identified differences (p ≤ 0.05) between the agility drills as well as between the agility drills and the sprinting and shuffling. Results can be used to guide the progression of agility ladder drills based on known intensity and allow practitioners to prioritize drills that are most similar to sport-specific movements such as sprinting and shuffling

BIOMECHANICAL ANALYSIS OF ACCELERATION LADDERS WITH VARYING STEP DISTANCES

This study assessed select kinetics and kinematics of each of the first three steps of the acceleration phase of sprinting using three different acceleration ladders. Subjects (N=15) performed sprints using acceleration ladders with short, medium, and long rung spacing, over two large force platforms. Multi-factorial repeated measure ANOVAs were used to assess horizontal and vertical ground reaction force (GRF), the ratio of horizontal to vertical GRF, the duration of vertical GRF, time between steps, distance between steps, and velocity between steps and across all steps. Main effects were significant (p ≤ 0.05) for all variables except time. Post-hoc analysis identified a variety of differences in the dependent variables in the analysis of steps, test condition and their interaction (p ≤ 0.05). Results show that greater velocity is attained with ladders that have longer step distances