Comparison of the Relationship between Lying and Standing Ultrasonography Measures of Muscle Morphology with Isometric and Dynamic Force Production Capabilities

The purpose of the current study was (1) to examine the differences between standing and lying measures of vastus lateralis (VL), muscle thickness (MT), pennation angle (PA), and cross-sectional area (CSA) using ultrasonography; and (2) to explore the relationships between lying and standing measures with isometric and dynamic assessments of force production—specifically peak force, rate of force development (RFD), impulse, and one-repetition maximum back squat. Fourteen resistance-trained subjects (age = 26.8 ± 4.0 years, height = 181.4 ± 6.0 cm, body mass = 89.8 ± 10.7 kg, back squat to body mass ratio = 1.84 ± 0.34) agreed to participate. Lying and standing ultrasonography images of the right VL were collected following 48 hours of rest. Isometric squat assessments followed ultrasonography, and were performed on force platforms with data used to determine isometric peak force (IPF), as well as RFD and impulse at various time points. Forty-eight hours later, one-repetition maximum back squats were performed by each subject. Paired-samples t-tests revealed statistically significant differences between standing and lying measurements of MT (p \u3c 0.001), PA (p \u3c 0.001), and CSA (p ≤ 0.05), with standing values larger in all cases. Further, standing measures were correlated more strongly and abundantly to isometric and dynamic performance. These results suggest that if practitioners intend to gain insight into strength-power potential based on ultrasonography measurements, performing the measurement collection with the athlete in a standing posture may be preferred

Repetition-to-Repetition Differences Using Cluster and Accentuated Eccentric Loading in the Back Squat

The current investigation was an examination of the repetition-to-repetition magnitudes and changes in kinetic and kinematic characteristics of the back squat using accentuated eccentric loading (AEL) and cluster sets. Trained male subjects (age = 26.1 ± 4.1 years, height = 183.5 ± 4.3 cm, body mass = 92.5 ± 10.5 kg, back squat to body mass ratio = 1.8 ± 0.3) completed four load condition sessions, each consisting of three sets of five repetitions of either traditionally loaded straight sets (TL), traditionally loaded cluster sets (TLC), AEL cluster sets (AEC), and AEL straight sets where only the initial repetition had eccentric overload (AEL1). Eccentric overload was applied using weight releasers, creating a total eccentric load equivalent to 105% of concentric one repetition maximum (1RM). Concentric load was 80% 1RM for all load conditions. Using straight sets (TL and AEL1) tended to decrease peak power (PP) (d = −1.90 to −0.76), concentric rate of force development (RFDCON) (d = −1.59 to −0.27), and average velocity (MV) (d = −3.91 to −1.29), with moderate decreases in MV using cluster sets (d = −0.81 to −0.62). Greater magnitude eccentric rate of force development (RFDECC) was observed using AEC at repetition three (R3) and five (R5) compared to all load conditions (d = 0.21⁻0.65). Large within-condition changes in RFDECC from repetition one to repetition three (∆REP1⁻3) were present using AEL1 (d = 1.51), demonstrating that RFDECC remained elevated for at least three repetitions despite overload only present on the initial repetition. Overall, cluster sets appear to permit higher magnitude and improved maintenance of concentric outputs throughout a set. Eccentric overload with the loading protocol used in the current study does not appear to potentiate concentric output regardless of set configuration but may cause greater RFDECC compared to traditional loading

Comparison of the Relationship between Lying and Standing Ultrasonography Measures of Muscle Morphology with Isometric and Dynamic Force Production Capabilities

The purpose of the current study was (1) to examine the differences between standing and lying measures of vastus lateralis (VL), muscle thickness (MT), pennation angle (PA), and cross-sectional area (CSA) using ultrasonography; and (2) to explore the relationships between lying and standing measures with isometric and dynamic assessments of force production—specifically peak force, rate of force development (RFD), impulse, and one-repetition maximum back squat. Fourteen resistance-trained subjects (age = 26.8 ± 4.0 years, height = 181.4 ± 6.0 cm, body mass = 89.8 ± 10.7 kg, back squat to body mass ratio = 1.84 ± 0.34) agreed to participate. Lying and standing ultrasonography images of the right VL were collected following 48 hours of rest. Isometric squat assessments followed ultrasonography, and were performed on force platforms with data used to determine isometric peak force (IPF), as well as RFD and impulse at various time points. Forty-eight hours later, one-repetition maximum back squats were performed by each subject. Paired-samples t-tests revealed statistically significant differences between standing and lying measurements of MT (p \u3c 0.001), PA (p \u3c 0.001), and CSA (p ≤ 0.05), with standing values larger in all cases. Further, standing measures were correlated more strongly and abundantly to isometric and dynamic performance. These results suggest that if practitioners intend to gain insight into strength-power potential based on ultrasonography measurements, performing the measurement collection with the athlete in a standing posture may be preferred

Repetition-to-Repetition Differences Using Cluster and Accentuated Eccentric Loading in the Back Squat

The current investigation was an examination of the repetition-to-repetition magnitudes and changes in kinetic and kinematic characteristics of the back squat using accentuated eccentric loading (AEL) and cluster sets. Trained male subjects (age = 26.1 ± 4.1 years, height = 183.5 ± 4.3 cm, body mass = 92.5 ± 10.5 kg, back squat to body mass ratio = 1.8 ± 0.3) completed four load condition sessions, each consisting of three sets of five repetitions of either traditionally loaded straight sets (TL), traditionally loaded cluster sets (TLC), AEL cluster sets (AEC), and AEL straight sets where only the initial repetition had eccentric overload (AEL1). Eccentric overload was applied using weight releasers, creating a total eccentric load equivalent to 105% of concentric one repetition maximum (1RM). Concentric load was 80% 1RM for all load conditions. Using straight sets (TL and AEL1) tended to decrease peak power (PP) (d = −1.90 to −0.76), concentric rate of force development (RFDCON) (d = −1.59 to −0.27), and average velocity (MV) (d = −3.91 to −1.29), with moderate decreases in MV using cluster sets (d= −0.81 to −0.62). Greater magnitude eccentric rate of force development (RFDECC) was observed using AEC at repetition three (R3) and five (R5) compared to all load conditions (d = 0.21–0.65). Large within-condition changes in RFDECC from repetition one to repetition three (∆REP1–3) were present using AEL1 (d = 1.51), demonstrating that RFDECC remained elevated for at least three repetitions despite overload only present on the initial repetition. Overall, cluster sets appear to permit higher magnitude and improved maintenance of concentric outputs throughout a set. Eccentric overload with the loading protocol used in the current study does not appear to potentiate concentric output regardless of set configuration but may cause greater RFDECCcompared to traditional loadin

Platform Dependent Verification: On Engineering Verification Tools for 21st Century

The paper overviews recent developments in platform-dependent explicit-state LTL model checking.Comment: In Proceedings PDMC 2011, arXiv:1111.006

Hybrid one-dimensional reversible cellular automata are regular

AbstractIt is shown that the set of hybrid one-dimensional reversible cellular automata (CA) with the periodic boundary condition is a regular set. This has several important consequences. For example, it allows checking whether a given CA is reversible and the random generation of a reversible CA from the uniform distribution, both using time polynomial in the size of the CA. Unfortunately, the constant term in the resulting random generation algorithm is much too large to be of practical use. We show that for the less general case of null boundary (NB) CA, this constant can be reduced drastically, hence facilitating a practical algorithm for uniform random generation. Our techniques are further applied asymptotically to count the number of reversible NBCA

Leveraging distributed explicit-state model checking for practical verification of liveness in hardware protocols

Protocol verification is a key component to hardware and software design. The proliferation of concurrency in modern designs stresses the need for accurate protocol models and scalable verification tools. Model checking is an approach for automatically verifying properties of designs, the main limitation of which is state-space explosion. As such, automatic verification of these designs can quickly exhaust the memory of a single computer. This thesis presents PReach, a distributed explicit-state model checker, designed to robustly harness the aggregate computing power of large clusters. The initial version verified safety properties, which hold if no error states can be reached. PReach has been demonstrated to run on hundreds of machines and explore state space sizes up to 90 billion, the largest published to date. Liveness is an important class of properties for hardware system correctness which, unlike safety, expresses more elaborate temporal reasoning. However, model checking of liveness is more computationally complex, and exacerbates scalability issues as compared with safety. The main thesis contribution is the extension of PReach to verify two key liveness-like properties of practical interest: deadlock-freedom and response. Our methods leverage the scalability and robustness of PReach and strike a balance between tractable verification for large models and catching liveness violations. Deadlock-freedom holds if from all reachable system states, there exists a sequence of actions that will complete all pending transactions. We find that checking this property is only a small overhead as compared to safety checking. We also provide a technique for establishing that deadlock-freedom holds of a parameterized system -- a system with a variable number of entities. Response is a stronger property than deadlock-freedom and is the most common liveness property of interest. In practical cases, fairness must be imposed on system models when model checking response to exclude those execution traces deemed inconsistent with the expected underlying hardware. We implemented a novel twist on established model checking algorithms, to target response properties with action-based fairness. This implementation vastly out-performs competing tools. This thesis shows that tractable verification of interesting liveness properties in large protocol models is possible.Science, Faculty ofComputer Science, Department ofGraduat

Energy-time complexity of algorithms : modelling the trade-offs of CMOS VLSI

Power consumption has become one of the most critical concerns for processor design. Parallelism offers a pathway to increased performance under power constraints — many slow processors can complete a parallel implementation of a task using less time and less energy than a fast uniprocessor. This relies on the energy-time trade-offs present in CMOS circuits, including voltage scaling. Understanding these trade-offs and their connection with algorithms will be a key for extracting performance in future multicore processor designs. I propose simple models for analysing algorithms and deriving lower bounds that reflect the energy-time trade-offs and parallelism of CMOS circuits. For example, the models constrain computational elements to lie in a two-dimensional topology. These elements, called processing elements (PEs), compute arbitrary functions of a constant number of input bits and store a constant-bounded memory. PEs are used to implement wires; thus subsuming and accounting for communication costs. Each operation of a PE takes time t and consumes energy e, where eta remains invariant for some fixed α > 0. Not only may different PEs independently trade time for energy in this way, but the same PE may vary the trade-off on an operation by operation basis. Using these models, I derive lower bounds for the ETα costs of sorting, addition and multiplication, where E and T are the total energy and time, and present algorithms that meet these bounds asymptotically. Clearly there exist many algorithms to solve each of these problems, and furthermore there are many choices of how to implement them with processing elements. Fortunately, the tight asymptotic bounds collapse the hierarchy of algorithms, implementations and schedules. This demonstrates that choosing other algorithms or layout schemes may only improve the energy-time "cost" by constant factors. In addition to analysing energy-time optimal algorithms for these problems, I also determine the complexity of many other well-established algorithms. This sheds light on the relative energy-time efficiency of these algorithms, revealing that some "fast" algorithms exploit free communication of traditional computation models. I show that energy-time minimal algorithms are not the same as those that minimize operation count or the computation depth.Science, Faculty ofComputer Science, Department ofGraduat