No Sun-like dynamo on the active star ζ Andromedae from starspot asymmetry.

Sunspots are cool areas caused by strong surface magnetic fields that inhibit convection. Moreover, strong magnetic fields can alter the average atmospheric structure, degrading our ability to measure stellar masses and ages. Stars that are more active than the Sun have more and stronger dark spots than does the Sun, including on the rotational pole. Doppler imaging, which has so far produced the most detailed images of surface structures on other stars, cannot always distinguish the hemisphere in which the starspots are located, especially in the equatorial region and if the data quality is not optimal. This leads to problems in investigating the north-south distribution of starspot active latitudes (those latitudes with more starspot activity); this distribution is a crucial constraint of dynamo theory. Polar spots, whose existence is inferred from Doppler tomography, could plausibly be observational artefacts. Here we report imaging of the old, magnetically active star ζ Andromedae using long-baseline infrared interferometry. In our data, a dark polar spot is seen in each of two observation epochs, whereas lower-latitude spot structures in both hemispheres do not persist between observations, revealing global starspot asymmetries. The north-south symmetry of active latitudes observed on the Sun is absent on ζ And, which hosts global spot patterns that cannot be produced by solar-type dynamos.

Inter- and intra-examiner reliability of leg-length differential measurement: a preliminary study.

The phenomenon of "short leg" has long been used and debated clinically. A uniquely chiropractic measurement technique was not studied in any of the few studies of reliability of measurement which have been reported. An inter- and intra-examiner reliability study was therefore performed to validate a prone leg length-differential test. Naive students (n = 40) were called, in random order, into three adjacent examining rooms where three experienced chiropractic clinicians measured differential leg lengths. Using standard placement a tape measure was read to the nearest mm to detect inequalities at the shoe-sole interface. The leg length differences were recorded, for both the straight and flexed legs prone positions, twice by each of the three clinicians. Intraclass correlations were significant for the two independent readings for all three examiners, indicating high reliability of the test. Good agreement among examiners was indicated as well by significant intraclass correlation in two of the three possible examiner combinations. These results argue strongly for the reality of the leg length inequality phenomenon and also that it can be reliably measured.