A THREE-DIMENSIONAL KINEMATIC ANALYSIS OF THE FRONT FLY-CAST

A fly caster must control the entire length of line to be projected while casting. This requires coordination of shoulder, elbow, and wrist movement. Little quantitative kinematic research describing the basic front fly cast has been published to date. The purpose of this study was to provide a three dimensional kinematic description of expert performance of the front fly cast, and to compare the results to fly casting instructional media. Twelve club level fly fishing experts, able to accurately cast with standardized equipment to a one meter target circle 12.9m away, were chosen as subjects. Each subject was videotaped indoors while performing five accurate basic front casts from a standard reference position. Two genlocked video cameras operated at 60 Hz were used for collection of the three-dimensional calibration frame and casting images. After data collection, seven body and rod handle reference position markers were digitized frame by frame for each camera view. The Direct Linear Transformation algorithm was utilized to provide the three dimensional coordinate locations of the markers. Within subject reliability data values obtained by analysis of two different casts from three randomly selected subjects demonstrated congruity between casts for the kinematic variables. The mean, standard deviation, standard error, and range of the quantified variables were reported and compared to the qualitative description of these variables in instructional publications. The group results revealed a consistent pattern of angular displacement and angular velocity among subjects for rod position to horizontal, elbow, wrist, and torso motion. Dissimilarities were noted for sagittal and frontal plane shoulder motion, and for rod displacement from the sagittal plane. Comparison of the study results to the qualitative descriptions of instructional authors revealed several differences. Subject data exhibited higher initial, midpoint, and ending rod position to horizontal angular displacements, and exhibited greater rod displacement from the sagittal plane, than the descriptions of these variables in the casting literature. More flexion at the elbow and less flexion at the shoulder were exhibited at the end of the backcast by the subjects than was described in the casting literature. The results of this study provided quantitative data for validation of current and future descriptions and analyses flycasting mechanics

Effective Field Theory and Unification in AdS Backgrounds

This work is an extension of our previous work, hep-th/0204160, which showed how to systematically calculate the high energy evolution of gauge couplings in compact AdS_5 backgrounds. We first directly compute the one-loop effects of massive charged scalar fields on the low energy couplings of a gauge theory propagating in the AdS background. It is found that scalar bulk mass scales (which generically are of order the Planck scale) enter only logarithmically in the corrections to the tree-level gauge couplings. As we pointed out previously, we show that the large logarithms that appear in the AdS one-loop calculation can be obtained within the confines of an effective field theory, by running the Planck brane correlator from a high UV matching scale down to the TeV scale. This result exactly reproduces our previous calculation, which was based on AdS/CFT duality. We also calculate the effects of scalar fields satisfying non-trivial boundary conditions (relevant for orbifold breaking of bulk symmetries) on the running of gauge couplings.Comment: LaTeX, 27 pages; minor typos fixed, comments adde

Climate-driven Shifts in Quantity and Seasonality of River Discharge over the past 1000 Years from the Hydrographic Apex of North America

Runoff generated from high elevations is the primary source of freshwater for western North America, yet this critical resource is managed on the basis of short instrumental records that capture an insufficient range of climatic conditions. Here we probe the effects of climate change over the past ~1000 years on river discharge in the upper Mackenzie River system based on paleoenvironmental information from the Peace-Athabasca Delta. The delta landscape responds to hydroclimatic changes with marked variability, while Lake Athabasca level appears to directly monitor overall water availability. The latter fluctuated systematically over the past millennium, with the highest levels occurring in concert with maximum glacier extent during the Little Ice Age, and the lowest during the 11th century, prior to medieval glacier expansion. Recent climate-driven hydrological change appears to be on a trajectory to even lower levels as high-elevation snow and glacier meltwater contributions both continue to decline

Systematics of Coupling Flows in AdS Backgrounds

We give an effective field theory derivation, based on the running of Planck brane gauge correlators, of the large logarithms that arise in the predictions for low energy gauge couplings in compactified AdS}_5 backgrounds, including the one-loop effects of bulk scalars, fermions, and gauge bosons. In contrast to the case of charged scalars coupled to Abelian gauge fields that has been considered previously in the literature, the one-loop corrections are not dominated by a single 4D Kaluza-Klein mode. Nevertheless, in the case of gauge field loops, the amplitudes can be reorganized into a leading logarithmic contribution that is identical to the running in 4D non-Abelian gauge theory, and a term which is not logarithmically enhanced and is analogous to a two-loop effect in 4D. In a warped GUT model broken by the Higgs mechanism in the bulk,we show that the matching scale that appears in the large logarithms induced by the non-Abelian gauge fields is m_{XY}^2/k where m_{XY} is the bulk mass of the XY bosons and k is the AdS curvature. This is in contrast to the UV scale in the logarithmic contributions of scalars, which is simply the bulk mass m. Our results are summarized in a set of simple rules that can be applied to compute the leading logarithmic predictions for coupling constant relations within a given warped GUT model. We present results for both bulk Higgs and boundary breaking of the GUT gauge group.Comment: 22 pages, LaTeX, 3 figures. Comments and references adde

Unification in 5D SO(10)

Gauge unification in a five dimensional supersymmetric SO(10) model compactified on an orbifold $S^1/(Z_2 \times Z_2^{\prime})$ is studied. One orbifolding reduces N=2 supersymmetry to N=1, and the other breaks SO(10) to the Pati-Salam gauge group \ps. Further breaking to the standard model gauge group is made through the Higgs mechanism on one of the branes. The differences of the three gauge couplings run logarithmically even in five dimensions and we can keep the predictability for unification as in four dimensional gauge theories. We obtain an excellent prediction for gauge coupling unification with a cutoff scale $M_* \sim 3 \times 10^{17}$ GeV and a compactification scale $M_c \sim 1.5 \times 10^{14}$ GeV. Finally, although proton decay due to dimension 5 operators may be completely eliminated, the proton decay rate in these models is sensitive to the placement of matter multiplets in the 5th dimension, as well as to the unknown physics above the cutoff scale.Comment: 33 pages, one reference added and fig. 3 caption correcte

Extra Dimensions at the Weak Scale and Deviations from Newtonian Gravity

We consider theories in which the Standard Model gauge fields propagate in extra dimensions whose size is around the electroweak scale. The Standard Model quarks and leptons may either be localized to a brane or propagate in the bulk. This class of theories includes models of Scherk-Schwarz supersymmetry breaking and universal extra dimensions. We consider the problem of stabilizing the volume of the extra dimensions. We find that for a large class of stabilization mechanisms the field which corresponds to fluctuations of the volume remains light even after stabilization, and has a mass in the $10^{-3}$ eV range. In particular this is the case if stabilization does not involve dynamics at scales larger than the cutoff of the higher dimensional Standard Model, and if the effective theory below the compactification scale is four dimensional. The mass of this field is protected against large radiative corrections by the general covariance of the higher dimensional theory and by the weakness of its couplings, which are Planck suppressed. Its couplings to matter mediate forces whose strength is comparable to that of gravity and which can give rise to potentially observable deviations from Newton's Law at sub-millimeter distances. Current experiments investigating short distance gravity can probe extra dimensions too small to be accessible to current collider experiments. In particular for a single extra dimension stabilized by the Casimir energy of the Standard Model fields compactification radii as small as 5 inverse TeV are accessible to current sub-millimeter gravity experiments.Comment: Minor corrections, conclusions unchanged. References adde

Energy band structure and intrinsic coherent properties in two weakly linked Bose Einstein Condensates

The energy band structure and energy splitting due to quantum tunneling in two weakly linked Bose-Einstein condensates were calculated by using the instanton method. The intrinsic coherent properties of Bose Josephson junction were investigated in terms of energy splitting. For $E_{C}/E_{J}\ll 1$, the energy splitting is small and the system is globally phase coherent. In the opposite limit, $E_{C}/E_{J}\gg 1$, the energy splitting is large and the system becomes a phase dissipation. Our reslults suggest that one should investigate the coherence phenomna of BJJ in proper condition such as $E_{C}/E_{J}\sim 1$.Comment: to appear in Phys. Rev. A, 2 figure

Dynamics and Berry phase of two-species Bose-Einstein condensates

In terms of exact solutions of the time-dependent Schrodinger equation for an effective giant spin modeled from a coupled two-mode Bose-Einstein condensate (BEC) with adiabatic and cyclic time-varying Raman coupling between two hyperfine states of the BEC, we obtain analytic time-evolution formulas of the population imbalance and relative phase between two components with various initial states, especially the SU(2)coherent state. We find the Berry phase depending on the number parity of atoms, and particle number dependence of the collapse revival of population-imbalance oscillation. It is shown that self-trapping and phase locking can be achieved from initial SU(2) coherent states with proper parameters.Comment: 18 pages,5 figure

Regularisation Techniques for the Radiative Corrections of Wilson lines and Kaluza-Klein states

Within an effective field theory framework we compute the most general structure of the one-loop corrections to the 4D gauge couplings in one- and two-dimensional orbifold compactifications with non-vanishing constant gauge background (Wilson lines). Although such models are non-renormalisable, we keep the analysis general by considering the one-loop corrections in three regularisation schemes: dimensional regularisation (DR), Zeta-function regularisation (ZR) and proper-time cut-off regularisation (PT). The relations among the results obtained in these schemes are carefully addressed. With minimal re-definitions of the parameters involved, the results obtained for the radiative corrections can be applied to most orbifold compactifications with one or two compact dimensions. The link with string theory is discussed. We mention a possible implication for the gauge couplings unification in such models.Comment: 37 pages, 1 Figure, LaTeX; minor correction

Precision Electroweak Data and Unification of Couplings in Warped Extra Dimensions

Warped extra dimensions allow a novel way of solving the hierarchy problem, with all fundamental mass parameters of the theory naturally of the order of the Planck scale. The observable value of the Higgs vacuum expectation value is red-shifted, due to the localization of the Higgs field in the extra dimension. It has been recently observed that, when the gauge fields propagate in the bulk, unification of the gauge couplings may be achieved. Moreover, the propagation of fermions in the bulk allows for a simple solution to potentially dangerous proton decay problems. However, bulk gauge fields and fermions pose a phenomenological challenge, since they tend to induce large corrections to the precision electroweak observables. In this article, we study in detail the effect of gauge and fermion fields propagating in the bulk in the presence of gauge brane kinetic terms compatible with gauge coupling unification, and we present ways of obtaining a consistent description of experimental data, while allowing values of the first Kaluza Klein mode masses of the order of a few TeV.Comment: 32 pages, 7 figures. References adde