Fixed-length measurement

A report130 of DSC measurements on polybenzimidazole fibers describes important differences for the glass transition temperature depending on die mechanical treatment of the fiber. An as-spun fiber exhibits a Tg at 387°C instead of 401°C for a drawn fiber free to shrink or 435°C for a drawn fiber widi fixed length. 

For the purpose of illustrating the application of the thermodynamic equation of state to experimental data, consider the plot given in Fig. 84 for the retractive force, measured at fixed length, against the absolute temperature for a hypothetical elastic substance. The slope at any temperature T gives the important quantity —(dS/dL)T,p according to Eq. (12) an increase in / with T at constant L shows immediately, therefore, that the entropy decreases with increase in length... 

Consider two bodies, i and j, connected by a bond of fixed length hij. We make the assumption that the only allowable relative motion between the two bodies is a rotation about hij. Let f) and rj locate (with respect to an inertial frame) the center of mass of body i and j respectively, and let Sy and Sji define the points of attachment for each body with respect to its center of mass. The position of the center of mass of body j with respect to that of body i is simply = fj — f). Finally, the scalar qij measures the relative angle of rotation about the bond hij. 

Time-of-flight is the simplest of mass analyzers. It determines the ndz ratio of ions by measuring the time for the ions to fly through a fixed length path to an ion detector. Each ion has the same kinetic energy when introduced into the analyzer, but the speed varies with the mass, causing each ion to arrive at the detector at different times. 

Using the flexible needle in vitro force measurement system described earlier, VanBuren et al. (1994) measured the force per cross-bridge of smooth muscle versus skeletal muscle myosin in vitro. In this elegant assay, the number of myosin heads per square micron was determined from the ATPase activity and the number of myosins capable of interacting with a fixed length of actin was calculated by assuming that all myo-... 

Every measure of genomic heterogeneity has, however, characteristic drawbacks. It is therefore advisable to confirm results obtained via one measure by other measures, and by checking that heterogeneities are not simply due to a few short outlier regions. For example, the standard deviation of fixed-length fragments is sensitive to outlier DNA... 

We have used several measures of GC heterogeneity the variation among fixed length windows, the sequence compositional complexity al different stringency levels, and the value of the GC corrclograms where top and bottom branches meet (not shown here). I or... 

Description of muscle contraction has essentially evolved into two separate approaches — lumped whole muscle models and specialized crossbridge models of the sarcomere. The former seek to interpret muscle s complex mechanical properties with a single set of model elements. Muscle experiments measure muscle force and length subjected to isometric (fixed length) conditions, isotonic (fixed load) conditions, and transient analysis where either length or load is rapidly changed. 

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