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ABSTRACT We use the magnetic field components measured by Zeeman Doppler imaging (ZDI) to calculate the stellar surface force and torque due to magnetic stresses for the fast rotators σ Ori E, 36 Lyn, and CU Vir, and the slow rotator τ Sco. If we assume the stars have spherical photospheres, the estimated torques give spin-down time-scales no larger than 7 × 105 yr. For σ Ori E, the predicted spin-down time-scale, ≃ 6000 yr, is much less than the observationally measured time-scale of ≃ 106 yr. However, for CU Vir, we find that the spin-down time-scale from its ZDI map is 7 × 105 yr in good agreement with its average rate of spin-down from 1960 to 2010. With the exception of τ Sco, the net force due to magnetic stresses at the stellar surface are large compared to the surface-integrated pressure. We discuss possible reasons for the large values of the forces (and torques), and suggest that the likely explanation is that rotation and the magnetic stresses create significant departures from spherical symmetry. 

ObjectiveAs opposed to postconcussion physical activity, the potential influence of cognitive activity on concussion recovery is not well characterised. This study evaluated the intensity and duration of daily cognitive activity reported by adolescents following concussion and examined the associations between these daily cognitive activities and postconcussion symptom duration. MethodsThis study prospectively enrolled adolescents aged 11–17 years with a physician-confirmed concussion diagnosis within 72 hours of injury from the emergency department and affiliated concussion clinics. Participants were followed daily until symptom resolution or a maximum of 45 days postinjury to record their daily cognitive activity (intensity and duration) and postconcussion symptom scores. ResultsParticipants (n=83) sustained their concussion mostly during sports (84%), had a mean age of 14.2 years, and were primarily male (65%) and white (72%). Participants reported an average of 191 (SD=148), 166 (SD=151) and 38 (SD=61) minutes of low-intensity, moderate-intensity and high-intensity daily cognitive activity postconcussion while still being symptomatic. Every 10 standardised minutes per hour increase in moderate-intensity or high-intensity cognitive activities postconcussion was associated with a 22% greater rate of symptom resolution (adjusted hazard ratio (aHR) 1.22, 95% CI 1.01 to 1.47). Additionally, each extra day’s delay in returning to school postconcussion was associated with an 8% lower rate of symptom resolution (aHR 0.92, 95% CI 0.85 to 0.99). ConclusionIn adolescents with concussion, more moderate-high intensity cognitive activity is associated with faster symptom resolution, and a delayed return to school is associated with slower symptom resolution. However, these relationships may be bidirectional and do not necessarily imply causality. Randomised controlled trials are needed to determine if exposure to early cognitive activity can promote concussion recovery in adolescents. 

Two carbonate units from Southwest Florida, the Caloosahatchee and Fort Thompson Formations, were studied using X-ray instruments to understand more about their origins. The Caloosahatchee Fm. is late Pliocene to early Pleistocene in age while the Fort Thompson Fm. is late Pleistocene in age. Powdered X-ray diffraction (PXRD) was used to obtain the mineral composition of these formations. PXRD revealed the Caloosahatchee Fm. consists predominantly of calcite with lesser quartz and aragonite. PXRD of the carbonate rocks from the Fort Thompson Fm. are also predominantly calcite with lesser quartz and aragonite. Fossils were picked by hand from poorly cemented Caloosahatchee Fm. samples and analyzed on the PXRD. These fossils were predominantly aragonite with minor calcite. Carbonates from the Caloosahatchee and Fort Thompson Fms. were also analyzed for their major and trace element geochemistry using a portable X-Ray fluorescence (pXRF). The Caloosahatchee Fm. has a Mg/Ca ratio which ranges from 0.07 to 0.10, Sr which ranges from 368 to 1650 ppm, and Al which ranges from 0.08 to 0.35 wt.%. No As was detected in the Caloosahatchee Fm. The Fort Thompson Fm. was divided into lower and upper units for pXRF analysis. The lower Fort Thompson Fm. has a Mg/Ca ratio which ranges from 0.08 to 0.10, Sr which ranges from 197 to 1097 ppm, and Al which ranges from 0.05 to 0.38 wt.%. The upper Fort Thompson Fm. has a Mg/Ca ratio which ranges from 0.07 to 0.10, Sr which ranges from 92 to 1015 ppm, and Al which ranges from 0.21 to 1.33 wt.%. The lower Fort Thompson Fm. has no As detected in it, but the upper Fort Thompson had 5 ppm As. The low (< 0.8) Mg/Ca ratio and calcite being the predominant mineral in both formations indicate they are limestone. The presence of quartz, and the Al values suggest both formations have terrestrial contributions and are not pure marine limestone. The higher Al of the upper Fort Thompsons suggest it might have the largest terrestrial contribution. The Sr values for the Caloosahatchee Fm. are higher than the Fort Thompson Fms. This could be due to a higher marine influence in the Caloosahatchee Fm. The PXRD suggests the aragonite is originating from the shells within the formations. The lack of significant As in all rocks suggests leaching of this metal into the environment is not a concern.