TEMPORAL COMPARISON OF HAMSTRING CO-CONTRACTION LATENCY IN ANTERIOR CRUCIATE DEFICIENT KNEES - A PILOT STUDY

Recently, anterior cruciate ligament (ACL) research has been focusing on strengthening the hamstring muscles, as previous studies have found there to be a significant stabilizing effect by the hamstrings in those subjects with anterior cruciate deficiencies. Research has primarily focused on whether differences existed between the strength (Moore & Wade, 1989; Seto, Wino, Morrissey, Medeiros & Mason, 1988), the electromyographical (EMG) output (Tibone & Antich, 1988), or the muscle activation patterns between the quadriceps and hamstrings. (Beard, Kyberd, Fergusson & Dodd, 1993; Jennings Seedhom, 1994). A key factor in hamstring co-contraction during gait is that of timing. Should hamstring cocontraction occur near to heelstrike, where the greatest anterior shear force is applied to the knee during a normal gait, or occur too far behind heelstrike, muscular strength is rendered useless. In such an event, stabilization cannot occur if the joint has already been displaced, or counteracting force has already been exhausted. This pilot study proposed to determine if latency exists between injured and uninjured knees, examining only temporal data relative to heelstrike. Similar studies involving static positions with an applied shear force have been performed and have had contradicting results. (Beard, Kyberd, Fergusson & Dodd, 1993; JeMings & Seedhom, 1994). To date, no temporal measures have been examined in dynamic movement. This may affect results as most joint receptors require motion for proprioception. Data collection procedures involved using a 3-channel EMG monitor to track the time heelstrike, hamstring contraction and quadriceps contraction during a 5-second period of normal walking/jogging on a treadmill. Speeds of 5 km/h and 7 km/h were used on incline, decline and flat surfaces. Data was collected at three randomly selected times for each condition and each leg. Differences found between injured and uninjured legs represent an area of concern for those in the field of rehabilitation. Research into variations in treatment methods to correct for latency in the hamstrings could provide a level of stability not before seen in non-surgical or even surgical patients. The next step to further this research will involve an eight-channel EMG monitor to track bilateral timing. A thorough patient history including Cincinnati and Lysholm scales of subjective functional ability will be included in the patient selection process

HAMSTRING CONTRACTILE TIMING IN ANTERIOR CRUCIATE LIGAMENT DEFICIENT PATIENTS

The purpose of this research is to examine contractile timing of the hamstrings in patients with anterior cruciate ligament (ACL) deficient knees. Ten patients were tested for hamstring contractile timing using Electromyographic (EMG) recordings during gait speeds of 3km/h and 5km/h on both a level and ten degree incline. An ANOVA analysis was used to demonstrate timing onset differences between the deficient and normal leg for each test condition and muscle onset timing was related to the Lysholm scale for perceived knee function. Significant interaction differences were found for legs and speed variations plus a negative correlation between functional scores and hamstring timing onset

Vapor-Liquid Equilibrium Data For The NH3-H2O System And Its Description With A Modified Cubic Equation Of State

New pressure-temperature-overall composition vapor-liquid equilibrium (VLE) data are reported for the ammonia-water system at five temperatures between 20 and 140 °C and up to 500 pela. These data have been converted to T-P-x data, and vapor-phase compositions have been calculated by means of a Rediich-Kwong equation of state modified to Include Peneloux\u27s volume translation and a density-dependent mixing rule. In order to achieve agreement of calculated vapor-phase compositions with previous literature results, H was necessary to use different kij values In the vapor and liquid phases. © 1991, American Chemical Society. All rights reserved

Thermodynamic Properties From A Cubic Equation Of State: Avoiding Trivial Roots And Spurious Derivatives

A simple method is presented to find and avoid trivial roots and spurious derivatives for a cubic equation of state. The method\u27s utility is demonstrated with some illustrative distillation calculations. © 1981, American Chemical Society. All rights reserved

Analytical approximation for the sphere-sphere Coulomb potential

A simple analytical expression, which closely approximates the Coulomb potential between two uniformly charged spheres, is presented. This expression can be used in the optical potential semiclassical analyses which require that the interaction be analytic on and near the real r-axis.Comment: 4 pages including 3 figures and 1 tabl

Financial Security in Later Life: A National Initiative and Model for eXtension

A national Extension initiative on Financial Security in Later Life was established to strengthen the Cooperative Extension System\u27s capacity to deliver personal finance education leading to financial security in later life. The initiative articulates the research that provides the foundation for Extension programs and models the use of the Internet for program design, delivery, and evaluation. The contributions of the initiative are enhanced capacity of Extension educators, shared resources, and aggregated evaluations. The development of the initiative provides insights for eXtension

Real-Gas Effects and Phase Separation in Underexpanded Jets at Engine-Relevant Conditions

A numerical framework implemented in the open-source tool OpenFOAM is presented in this work combining a hybrid, pressure-based solver with a vapor-liquid equilibrium model based on the cubic equation of state. This framework is used in the present work to investigate underexpanded jets at engine-relevant conditions where real-gas effects and mixture induced phase separation are probable to occur. A thorough validation and discussion of the applied vapor-liquid equilibrium model is conducted by means of general thermodynamic relations and measurement data available in the literature. Engine-relevant simulation cases for two different fuels were defined. Analyses of the flow field show that the used fuel has a first order effect on the occurrence of phase separation. In the case of phase separation two different effects could be revealed causing the single-phase instability, namely the strong expansion and the mixing of the fuel with the chamber gas. A comparison of single-phase and two-phase jets disclosed that the phase separation leads to a completely different penetration depth in contrast to single-phase injection and therefore commonly used analytical approaches fail to predict the penetration depth.Comment: Preprint submitted to AIAA Scitech 2018, Kissimmee, Florid

On the B and J/Psi Cross Section Measurements at Ua1 and CDF

We analise the implications of the measurement of $B$ and $J/\psi$ inclusive \pt\ distributions performed in $p\bar p$ collisions by the UA1 and CDF experiments.Comment: 16 pages + 8 topdrawer figs included at the end, Latex, IFUP-TH 2/9