Abrupt changes in high-latitude nutrient supply to the Atlantic during the last glacial cycle

The supply of nutrients to the low-latitude thermocline is largely controlled by intermediate-depth waters formed at the surface in the high southern latitudes. Silicic acid is an essential macronutrient for diatoms, which are responsible for a significant portion of marine carbon export production. Changes in ocean circulation, such as those observed during the last deglaciation, would influence the nutrient composition of the thermocline and, therefore, the relative abundance of diatoms in the low latitudes. Here we present the first record of the silicic acid content of the Atlantic over the last glacial cycle. Our results show that at intermediate depths of the South Atlantic, the silicic acid concentration was the same at the Last Glacial Maximum (LGM) as it is today, overprinted by high silicic acid pulses that coincided with abrupt changes in ocean and atmospheric circulation during Heinrich Stadials and the Younger Dryas. We suggest these pulses were caused by changes in intermediate water formation resulting from shifts in the subpolar hydrological cycle, with fundamental implications for the nutrient supply to the Atlantic.

Long-Term Comparison of Video-Assisted Thoracic Sympathectomy and Clinical Observation for the Treatment of Palmar Hyperhidrosis in Children Younger Than 14

The results of video-assisted thoracic sympathectomy (VATS)in children are unknown. To investigate the improvement in quality of life (QOL) of a group of 45 children who did and did not undergo VATS for the treatment of palmar hyperhidrosis (PH) 4 years after the initial evaluation. Forty-five children with PH were initially evaluated. Children were divided into two groups: 30 in the VATS group and 15 in the control group. We studied the evolution of PH, negative effect of hyperhidrosis on the QOL before the treatment, and improvement in QOL after treatment. Twenty-five patients (83.4%) in the VATS group experienced great improvement in PH, and five (16.6%) experienced partial improvement; 12 (80.0%) children from the control group had some type of improvement, and three (20.0%) had partial improvement. Two (13.3%) children in the control group and 23 (76.7%) in the VATS group had great improvement in QOL. For children with PH and poor QOL, VATS is better than no treatment. It produces better results with regard to sweating and greater improvement in QOL.