R. Szabo

Stress carpal tunnel pressures in patients with carpal tunnel syndrome and normal patients

Twenty-two patients with carpal tunnel syndrome scheduled to have a carpal tunnel release, and six volunteer control subjects had carpal tunnel pressures measured with their wrist in neutral position, maximum flexion, and maximum extension. The wrist was then repetitively flexed and extended to maximum position at a rate of 30 full cycles per minute for 1 minute. Pressures were then continually monitored and recorded at 30-second intervals. The pressures were found to be significantly elevated in the immediate post-exercise period in the patients with carpal tunnel syndrome, and they demonstrated a prolonged recovery time to reach the resting pressure when compared with the normal control subjects. This property of prolonged recovery time in patients with carpal tunnel syndrome suggests a possible cause for carpal tunnel syndrome in the occupational setting.

Beat Cepheids as probes of stellar and galactic metallicity

The mere location of a beat Cepheid model in a period ratio versus period diagram (Petersen diagram) puts very tight constraints on its metallicity Z. The beat Cepheid Petersen diagrams are revisited with linear nonadiabatic turbulent convective models, and their accuracy as a probe for stellar metallicity is evaluated. They are shown to be largely independent of the helium content Y, and they are also only weakly dependent on the mass-luminosity relation that is used in their construction. However, they are found to show sensitivity to the relative abundances of the elements that are lumped into the metallicity parameter Z. Rotation is estimated to have but a small effect on the pulsation metallicities. A composite Petersen diagram is presented that allows one to read off upper and lower limits on the metallicity Z from the measured period P0 and period ratio P10.

The Cepheid phase lag revisited

We compute the phase lags between the radial velocity curves and the light curves ΔΦ1 = - for classical Cepheid model sequences both in the linear and the nonlinear regimes. The nonlinear phase lags generally fall below the linear ones except for high-period models, in which they lie above, and of course for low pulsation amplitudes, in which the two merge. The calculated phase lags show good agreement with the available observational data of normal amplitude Galactic Cepheids. The metallicity has but a moderate effect on the phase lag, while the mass-luminosity relation and the parameters of the turbulent convective model (time-dependent mixing length) mainly influence the modal selection and the period, which is then reflected in the period-ΔΦ1 diagram. We discuss the potential application of this observable as a discriminant for pulsation modes and as a test for ultralow-amplitude (ULA) pulsation.

Pulsating B-type stars in the young open cluster h Persei (NGC 869)

We announce the discovery of six β Cephei stars and many other variable stars in the young open cluster h Persei (NGC 869). The cluster seems to be very rich in variable B-type stars, similarly to its twin, χ Persei (NGC 884).