Data on the relationship between the electrical conductivity and the chemistry of ice cores from the polar regions are summarized. The electrical conductivity measurement is used as a proxy for dc conductivity, while dielectric profiling gives high-frequency conductivity. The dc conductivity seems to be controlled entirely by the acidity of the ice, with a secondary effect of the accompanying anion. There is no positive response when huge excesses of sea salt, ammonium, or calcium are present, except in ice where brine is present. The high-frequency conductivity is controlled by acidity, ammonium, and chloride. This finding can be accommodated within Jaccard theory, but the relative response at high frequency to the three ions seems puzzling. The possibility that dc conduction may be through grain boundaries can also not be discounted.
Agut needed just one match point to secure victory and will play either Tomas Berdych or Marco Cecchinato in Saturday’s final.It is the second time he has beaten Djokovic in his career and both victories occurred in a semi-final.The first win came in October 2016 in Shanghai. Djokovic was also world number one at that stage.Questions may be asked about how tired the Serb was, as he played two games each day for three days in singles and doubles, prior to Friday’s defeat.Share on: WhatsApp Doha, Qatar | AFP | Novak Djokovic was surprisingly defeated in Doha on Friday, beaten in the Qatar Open semi-final by world number 24, Roberto Bautista Agut, 6-3, 6-7 (8/6), 6-4.The Serb fell to his first defeat of the season in a high-quality contest lasting more than two-and-a-half hours, which saw the Spaniard lose his first set of the week but still come back to defeat the world number one.“I will remember this match for [the rest] of my life,” said the 30-year-old.“I can’t be more happy than I am now.”