Voyager 2 radio observations of uranus

Within distances to Uranus of about 6 x 10(6) kilometers (inbound) and 35 x 10(6) kilometers (outbound), the planetary radio astronomy experiment aboard Voyager 2 detected a wide variety of radio emissions. The emission was modulated in a period of 17.24 +/- 0.01 hours, which is identified as the rotation period of Uranus' magnetic field. Of the two poles where the axis of the off-center magnetic dipole (measured by the magnetometer experiment aboard Voyager 2) meets the planetary surface, the one closer to dipole center is now located on the nightside of the planet. The radio emission generally had maximum power and bandwidth when this pole was tipped toward the spacecraft. When the spacecraft entered the nightside hemisphere, which contains the stronger surface magnetic pole, the bandwidth increased dramatically and thereafter remained large. Dynamically evolving radio events of various kinds embedded in these emissions suggest a Uranian magnetosphere rich in magnetohydrodynamic phenomena.     

Elevation in brain temperature during paradoxical sleep

During ordinary sleep, the temperature of the rabbit brain tended to drop, but during paradoxical sleep it rose sharply 0.1 degrees to 0.4 degrees C, a greater elevation than was observed during arousal. Changes in body temperature generally did not parallel the alterations in brain temperature. Shifts of direct-current potential in the brain are basically independent of the changes in brain temperature.     

Field-applying an inexpensive, 13C-depleted,labile carbon source to study in situ fate and short-term effects on soils

Background

Labile carbon (C_labile) limits soil microbial growth and is critical for soil functions like nitrogen (N) immobilization. Most experiments evaluating C_labile additions use laboratory incubations. We need to field-apply C_labile to fully understand its fate and effects on soils, especially at depth, but high cost and logistical difficulties hinder this approach.

Aims

Here, we evaluated the impact of adding an in situ pulse of an inexpensive and ¹³C-depleted source of C_labile—crude glycerol carbon (C_glyc), a by-product from biodiesel production—to agricultural soils under typical crop rotations in Iowa, USA.

Methods

We broadcast-applied C_glyc at three rates (0, 216, and 866 kg C ha⁻¹) in autumn after soybean harvest, tracked its fate, and measured its impact on soil C and N dynamics to four depths (0–5, 5–15, 15–30, and 30–45 cm). Nineteen days later, we measured C_glyc in microbial biomass carbon (MBC), salt-extractable organic C, and potentially mineralizable C pools. We paired these measurements with nitrate N (NO₃⁻–N) and potential net N mineralization to examine short-term effects on N cycling.

Results

C_glyc was found to at least 45-cm depth with the majority in MBC (18%–23% of total C_glyc added). The δ¹³C values of the other measured C pools were too variable to accurately track the C_labile fate. NO₃⁻–N was decreased by 13%–57% with the 216 and 866 kg C ha⁻¹ rates, respectively, and was strongly related to greater microbial uptake of C_glyc (i.e., immobilization via microbial biomass). Crude glycerol application had minor effects on soil pH—the greatest rate decreased pH 0.18 units compared to the control.

Conclusions

Overall, glycerol is an inexpensive and effective way to measure in situ, C_labile dynamics with soil depth—analogous to how mobile, dissolved organic C might behave in soils—and can be applied to rapidly immobilize NO₃⁻–N.