EFFECTS OF INDEPENDENT CRANK ARMS AND SLOPE ON PEDALING MECHANICS

The aim of this study was to identify the effects of independent crank arms and slope on pedaling kinetics during an anaerobic maximal-effort cycling bout. After undergoing 6 weeks of training with independent crank arms, each of 6 male cyclists completed four 30 s Wingate tests under different cycling conditions of: fixed crank arms on level surface; fixed crank arms on a slope; independent crank arms on level, and; independent crank arms on a slope. Two-dimensional pedal forces recorded using instrumented pedals were used to derive pedaling effectiveness, work distribution and power output. The effects of the crank arms and the slope were minimal, but highly effective and consistent pedaling force (90% effectiveness, 70% work and effective force of 155±6 N) was observed between 45-135° of the crank cycle in all experimental conditions

FORWARD SEAT POSITION EFFECTS ON CYCLING KINEMATICS

The aim of this study was to identify the effects of fore-aft position of the seat on kinematics during a submaixmal cycling session. Each of four recreational athletes (2 road cyclists, 2 triathletes) completed a 20-km simulated course under two different seat positions: tip of seat 5 cm in front and 5 cm behind the crank axis. Trunk and leg kinematics were determined using three-dimensional motion capture system. Bringing the seat position forward resulted in a more extended trunk-hip region (116±5° vs.122±3° of flexion); however, the source of the extension varied among individuals arising from the pelvis and the thigh in different participants. The knee joint angle range of motion and pattern were unaffected by the seat position. These results imply that participants used different muscle activation strategies in response to the change in riding position

Vortices, Q-balls and Domain Walls on Dielectric M2-branes

We study BPS solitons in N=6 U(N) \times U(N) Chern-Simons-matter theory deformed by an F-term mass. The F-term mass generically breaks N=6 supersymmetry down to N=2. At vacua, M2-branes are polarized into a fuzzy S^3 forming a spherical M5-brane with topology \mathbf{R}^{1,2} \times S^3. The polarization is interpreted as Myers' dielectric effect caused by an anti-self-dual 4-form flux T_4 in the eleven-dimensional supergravity. Assuming a polarized M2-brane configuration, the model effectively reduces to the well-known abelian Chern-Simons-Higgs model studied in detail by Jackiw-Lee-Weinberg. We find that the potential for the fuzzy S^3 radius agrees with the one calculated from the M5-brane point of view at large N. This effective model admits not only BPS topological vortex and domain wall solutions but also non-topological solitons that keep 1/4 of the manifest N=2 supersymmetry. We also comment on the reduction of our configuration to ten dimensions.Comment: references added, minor modification

Carrier concentrations in Bi_{2}Sr_{2-z}La_{z}CuO_{6+\delta} single crystals and their relation to Hall coefficient and thermopower

We measured the thermopower S and the Hall coefficients R_H of Bi_{2}Sr_{2-z}La_{z}CuO_{6+\delta} (BSLCO) single crystals in a wide doping range, in an effort to identify the actual hole concentrations per Cu, p, in this system. It is found that the "universal" relation between the room-temperature thermopower and T_c does not hold in the BSLCO system. Instead, comparison of the temperature-dependent R_H data with other cuprate systems is used as a tool to identify the actual p value. To justify this approach, we compare normalized R_H(T) data of BSLCO, La_{2-x}Sr_{x}CuO_{4} (LSCO), YBa_{2}Cu_{3}O_{y}, and Tl_{2}Ba_{2}CuO_{6+\delta}, and demonstrate that the R_H(T) data of the LSCO system can be used as a template for the estimation of p. The resulting phase diagram of p vs T_c for BSLCO suggests that T_c is anomalously suppressed in the underdoped samples, becoming zero at around p ~ 0.10, while the optimum T_c is achieved at p ~ 0.16 as expected.Comment: 4 pages including 5 figures, accepted for publication in Phys. Rev. B, Rapid Communication

A Monopole Instanton-Like Effect in the ABJM Model

Making use of ansatzs for the form fields in the 10d type IIA supergravity version of the ABJM model, we come with a solution in the Euclidean signature recognized as a monopole instanton-like object. Indeed we will see that we can have a (anti) self-dual solution at a special limit. While as a topological object, its back-reaction on the original background should be ignorable, we show the energy-momentum tensors vanish exactly. On the field theory side, the best counterpart is an U(1) gauge field of a gauge transformation. To adjust with bulk, the gauge field must prompt to a dynamic one without adding any kinetic term for this dual photon except a marginal, abelian AB-type Chern-Simons term on the boundary. We will see how both side solutions match next to another confirmation from some earlier works of this vortex-particle duality.Comment: 15 pages, minor changes of some formulas, few typos fixed, and a reference adde

Constructing Self-Dual Strings

We present an ADHMN-like construction which generates self-dual string solutions to the effective M5-brane worldvolume theory from solutions to the Basu-Harvey equation. Our construction finds a natural interpretation in terms of gerbes, which we develop in some detail. We also comment on a possible extension to stacks of multiple M5-branes.Comment: 1+19 pages, presentation improved, minor corrections, published versio

Higher derivative effects on eta/s at finite chemical potential

We examine the effects of higher derivative corrections on eta/s, the ratio of shear viscosity to entropy density, in the case of a finite R-charge chemical potential. In particular, we work in the framework of five-dimensional N =2 gauged supergravity, and include terms up to four derivatives, representing the supersymmetric completion of the Chern-Simons term A \wedge Tr (R \wedge R). The addition of the four-derivative terms yields a correction which is a 1/N effect, and in general gives rise to a violation of the eta/s bound. Furthermore, we find that, once the bound is violated, turning on the chemical potential only leads to an even larger violation of the bound.Comment: Typos fixed, references and comments on conventions adde