The Stratigraphy and Geochemistry of the Crescent Formation Basalts and the Bedrock Geology of Associated Igneous Rocks Near Bremerton, Washington

A stratigraphic section developed for the Bremerton rocks in the Kitsap Peninsula suggests formation by rifting in a marine environment. Basal gabbro, dated by 40Ar/39Ar at 49.8 Ma plus or minus 0.8 Ma, and associated mafic to felsic plutonics, appear to be the source of a mafic dike complex that composes 100% of the stratigraphic level above the plutonics. These dikes are the apparent feeders to overlying submarine and subaerial volcanics. The previously unrecognized submarine sequence consists of interbedded basaltic breccia, tuffs, basalt flows, and basaltic sandstone, siltstone, and conglomerate. Approximately 1 km of columnar basalt flows cap the sequence. Structures in the Bremerton rocks suggest that as many as four deformations may have affected these rocks. In the middle Eocene, extension to the north or northwest caused rifting and emplacement of the mafic dikes and lavas; several faults show that this extension was joined or followed by northeast-directed compression. Small faults and shears may have formed later by compression to the northwest. Reactivation of one of these faults and emplacement of northwest-striking Cascade arc(?) dikes suggest the latest deformation was extension to the northeast. The gabbro and basalts have chemistry transitional between N-type MORB and enriched ocean island basalt. Large-ion-lithophile to high-field-strength trace element ratios are similar to those of back-arc basin basalt. Felsic plutonics are enriched in elements (especially Zr) indicative of an arc influence. Several dikes intruding the gabbro are chemically indistinguishable from P-type (plume) ocean island basalt. Stratigraphic sections were developed in the basalts of the Crescent Formation and for basalts near Port Townsend in the Olympic Peninsula. Comparison to the subaerial basalts near Bremerton shows that the latter are quite similar to the upper subaerial Crescent Formation basalts and Port Townsend basalts. New chemical data for 16 flows of the Olympic Peninsula basalts are also similar to that of the Bremerton rocks. Stratigraphic and chemical similarities imply that rocks of all three areas are coeval. Deposition of the Crescent Formation basalts on a continentally-derived fan, stratigraphic and structural characteristics of the Bremerton rocks, and geochemical data on rocks of ail three areas suggest that these rocks formed by rifting of the western margin of the North America continent. Following rifting and basalt generation, the rocks may have moved north due to oblique convergence of the oceanic and continental plates, where they were thrust under Vancouver Island along the Leech River Fault. Thrusting moved outboard of the basalts and underlying fan; continued convergence thrust marine sediments that make up the Olympic core rocks beneath the basalts and underlying fan

Hip Torque Is a Mechanistic Link Between Sprint Acceleration and Maximum Velocity Performance: A Theoretical Perspective

Sprinting performance is critical for a variety of sports and competitive activities. Prior research has demonstrated correlations between the limits of initial acceleration and maximum velocity for athletes of different sprinting abilities. Our perspective is that hip torque is a mechanistic link between these performance limits. A theoretical framework is presented here that provides estimates of sprint acceleration capability based on thigh angular acceleration and hip torque during the swing phase while running at maximum velocity. Performance limits were calculated using basic anthropometric values (body mass and leg length) and maximum velocity kinematic values (contact time, thigh range of motion, and stride frequency) from previously published sprint data. The proposed framework provides a mechanistic link between maximum acceleration and maximum velocity, and also explains why time constant values (tau, ratio of the velocity limit to acceleration limit) for sprint performance curves are generally close to one-second even for athletes with vastly different sprinting abilities. This perspective suggests that specific training protocols targeted to improve thigh angular acceleration and hip torque capability will benefit both acceleration and maximum velocity phases of a sprint

UPPER EXTREMITY MOTION AND SPRINT RUNNING: A FAREWELL TO ARMS?

Despite a lack of prior research on the topic, the sport coaching community has popularized the use of arm drills for athletes with the intent to enhance sprinting performance. The purpose of this study was to identify the effect of self-restricted arm motion on sprint running velocity. Track & field athletes and team sport athletes (n=15) completed 12 30-meter sprints (six with normal arm motion, six with restricted arm motion) while radar data was collected to quantify running velocity. Using a mono-exponential function, velocity profiles were created for each trial which produced four outcome variables: vmax, amax, τ, and 30-meter sprint time. Differences in group means for all four outcome variables were not substantial between the two experimental conditions. It was concluded that the use of arm motion during maximal effort sprinting does not play a major role in running velocity enhancement

Human Sprint Running Mechanics: Do Right and Left Legs Apply Equal Ground Forces?

Introduction: A growing body of research has focused on between-leg asymmetry as a critical factor for athletic performance and dysfunction. Specifically, various measures of between-leg asymmetry during running have been investigated in both healthy and injured populations. However, while the most important factor for running performance is the magnitude and rate of ground force application, it is not known whether the right and left legs typically apply equal ground forces at faster running speeds. Objective: In a healthy population of athletic female participants, we aimed to: 1) compare the mechanics of ground force application between right and left legs during moderate and top speed running, and 2) evaluate if the right vs. left leg asymmetries observed at intermediate speeds are more pronounced at faster speeds. Hypothesis: We hypothesized that the forces applied by the right and left legs of healthy athletes would agree to within 10% or less at both moderate and top speed. Participants: Nine female intercollegiate soccer players volunteered for the study (age: 19.4 ± 1.0 years, height: 1.72 ± 0.04 m, mass: 69.0 ± 7.2 kg). Data Collection: Ground force data was acquired at 1,000 Hz using a custom high-speed, three-axis force treadmill (AMTI, Watertown, MA). Data was analyzed for trials at 5.0 m•s-1 and each individual’s top speed. Top speed was defined as the fastest speed where the participant could complete eight consecutive steps on the treadmill without drifting backward more than 0.2 m. Outcome Measures: Ground contact time, vertical force, and vertical impulse were analyzed. Vertical force was normalized to body weight (Wb) and vertical impulse was calculated in body weight • seconds (Wb•s). For all trials, these variables were averaged for right vs. left footfalls, and percentage difference was calculated to quantify between-leg asymmetry. Results: Top speeds ranged from 7.21 to 8.26 m•s-1 (7.83 ± 0.38 m•s-1). At 5.0 m•s-1, the mean between-leg asymmetry was 2.3 ± 1.2 % for ground contact time, 1.9 ± 1.3 % for vertical force, and 2.3 ± 1.9 % for vertical impulse. At top speed, the mean between-leg asymmetry was 3.5 ± 2.8 % for ground contact time, 5.5 ± 3.0 % for vertical force, and 8.3 ± 4.8 % for vertical impulse. Conclusions: We conclude that the right and left legs apply ground force similarly during moderate and top-speed sprint running in healthy female athletes

A general relationship links gait mechanics and running ground reaction forces

The relationship between gait mechanics and running ground reaction forces is widely regarded as complex. This viewpoint has evolved primarily via efforts to explain the rising edge of vertical force– time waveforms observed during slow human running. Existing theoretical models do provide good rising-edge fits, but require more than a dozen input variables to sum the force contributions of four or more vague components of the body’s total mass (mb). Here, we hypothesized that the force contributions of two discrete body mass components are sufficient to account for vertical ground reaction force– time waveform patterns in full (stance foot and shank, m1=0.08mb; remaining mass, m2=0.92mb). We tested this hypothesis directly by acquiring simultaneous limb motion and ground reaction force data across a broad range of running speeds (3.0–11.1 m s−1 ) from 42 subjects who differed in body mass (range: 43–105 kg) and foot-strike mechanics. Predicted waveforms were generated from our two-mass model using body mass and three stride-specific measures: contact time, aerial time and lower limb vertical acceleration during impact. Measured waveforms (N=500) differed in shape and varied by more than twofold in amplitude and duration. Nonetheless, the overall agreement between the 500 measured waveforms and those generated independently by the model approached unity (R2 =0.95 ±0.04, mean±s.d.), with minimal variation across the slow, medium and fast running speeds tested (ΔR2 ≤0.04), and between rear-foot (R2 =0.94±0.04, N=177) versus fore-foot (R2 =0.95±0.04, N=323) strike mechanics. We conclude that the motion of two anatomically discrete components of the body’s mass is sufficient to explain the vertical ground reaction force–time waveform patterns observed during human running

The Effects of Lower Body Positive Pressure Treadmill Running on Acute Femoral Cartilage Deformation

Purpose: Examine and compare the acute response of femoral cartilage in healthy individuals after running at full bodyweight (BW) (100%) and 80% BW on a lower body positive pressure treadmill. Methods: Crossover study consisted of 20 total healthy participants (10 males, 10 females). Femoral cartilage width was assessed using ultrasonography before and after the assigned running conditions. The control condition consisted of running at 6mph for 30 minutes at 100% BW, while the experimental condition consisted of running at 6mph for 30 minutes at 80% BW. Each participant ran both BW conditions, exactly one week apart. The order of conditions was randomly assigned to each participant. All running conditions were completed on the same AlterG Via X treadmill. Results: A significant reduction in cartilage width was found in both the right (p=0.001) and left (p=0.016) knees after running at 100% BW. Baseline cartilage measurements were comparative prior to each running condition and between limbs. There were no significant differences between limbs for either running condition. A significant reduction in cartilage width was seen after running at 80% body weight only in the right lateral compartment (p=0.006). Cartilage showed greater deformation after 100% BW than 80% BW in right (p=0.033) and left (p=0.011) knees. Conclusions: Cartilage thickness change proved to be lower after 80% BW running compared to 100% BW, which could have implications for long term cartilage health and future research into anti-gravity running

Limitations of Quantum Simulation Examined by Simulating a Pairing Hamiltonian using Nuclear Magnetic Resonance

Quantum simulation uses a well-known quantum system to predict the behavior of another quantum system. Certain limitations in this technique arise, however, when applied to specific problems, as we demonstrate with a theoretical and experimental study of an algorithm to find the low-lying spectrum of a Hamiltonian. While the number of elementary quantum gates does scale polynomially with the size of the system, it increases inversely to the desired error bound $\epsilon$. Making such simulations robust to decoherence using fault-tolerance constructs requires an additional factor of $1/ \epsilon$ gates. These constraints are illustrated by using a three qubit nuclear magnetic resonance system to simulate a pairing Hamiltonian, following the algorithm proposed by Wu, Byrd, and Lidar.Comment: 6 pages, 2 eps figure

Running impact forces: from half a leg to holistic understanding – comment on Nigg et al.

Running impact forces have immediate relevance for the muscle tuning paradigm proposed here and broader relevance for overuse injuries, shoe design and running performance. Here, we consider their mechanical basis. Several studies demonstrate that the vertical ground reaction force-time (vGRFT) impulse, from touchdown to toe-off, corresponds to the instantaneous accelerations of the body’s entire mass (Mb) divided into two or more portions. The simplest, a two-mass partitioning of the body (lower-limb, M1=0.08•Mb; remaining mass, M2=0.92•Mb) can account for the full vGRFT waveform under virtually all constant-speed, level-running conditions. Model validation data indicate that: 1) the non-contacting mass, M2, often accounts for one-third or more of the early “impact” portion of the vGRFT, and 2) extracting a valid impact impulse from measured force waveforms requires only lower-limb motion data and the fixed body mass fraction of 0.08 for M1

Resource Requirements for Fault-Tolerant Quantum Simulation: The Transverse Ising Model Ground State

We estimate the resource requirements, the total number of physical qubits and computational time, required to compute the ground state energy of a 1-D quantum Transverse Ising Model (TIM) of N spin-1/2 particles, as a function of the system size and the numerical precision. This estimate is based on analyzing the impact of fault-tolerant quantum error correction in the context of the Quantum Logic Array (QLA) architecture. Our results show that due to the exponential scaling of the computational time with the desired precision of the energy, significant amount of error correciton is required to implement the TIM problem. Comparison of our results to the resource requirements for a fault-tolerant implementation of Shor's quantum factoring algorithm reveals that the required logical qubit reliability is similar for both the TIM problem and the factoring problem.Comment: 19 pages, 8 figure

Do Horizontal Forces Matter For Horizontal Running?

DO HORIZONTAL FORCES MATTER FOR HORIZONTAL RUNNING? Kenneth P. Clark, Laurence J. Ryan, and Peter G. Weyand Southern Methodist University, Locomotor Performance Laboratory, Department of Applied Physiology and Wellness, Dallas, TX 75206 Classification of First Author: Doctoral Student Introduction: The application of ground force is widely recognized as the critical determinant of running speed. At maximal speeds, 90-98% of the total force applied is directed vertically into the running surface while horizontal (fore-aft) contributions are relatively small. Despite their small magnitude, horizontal forces are clearly essential for balance and may be important for other reasons. However, the pattern of horizontal force application across faster speeds is not well understood. Objective: For moderate to top speeds, we aimed to determine whether: 1) the horizontal forces required increase substantially, and 2) horizontal forces become larger relative to vertical forces. Participants: Two male and three female athletes volunteered for the study (age: 19.0 ± 0.6 years, height: 1.75 ± 0.06 m, mass: 71.0 ± 8.2 kg). Data Collection: Trials were completed on a high-speed, three-axis force treadmill (AMTI, Watertown, MA), with ground force data acquired at 1,000 Hz. Data was analyzed from each individual’s top speed and submaximal trials at 5.0 and 7.0 m/s. Top speed was determined by the fastest speed where the participant could complete eight steps without drifting backward 0.2 m. Outcome Measures: Because center of mass motion is determined by the mass-specific force applied and the time of force application, (i.e. impulse, or product of average force and time of application, or area under the force-time curve), we analyzed both average vertical and horizontal forces and impulses for every step. Average horizontal forces and impulses were calculated as the absolute value for the braking and propulsive phases of the horizontal force-time curve. Forces were standardized to body weight (Wb) and impulses calculated in body weight • seconds (Wb•s). The ratio of average vertical impulse to average horizontal impulse was calculated for each runner across speeds. Results: From 5.0 m/s to top speed, mean vertical and horizontal forces increased from 1.70 to 1.99 Wb and 0.29 to 0.34 Wb, respectively, and mean vertical and horizontal impulses decreased from 0.30 to 0.24 Wb•s and 0.05 to 0.04 Wb•s, respectively. From 5.0 m/s to top speed, the ratio of vertical to horizontal impulses varied by only 5.2% on average over a 1.5 to 2.0-fold range of speeds for the individuals tested and did so without consistent direction. Conclusions: The average horizontal forces and the ratio of vertical to horizontal impulses did not vary appreciably across a range of faster running speeds in a small sample of athletic subjects