Isabelle Rosso, PhD, who also works in Yurgelun-Todd's lab, and colleagues reported that as adolescents' abstract reasoning skills increased, so did their levels of social anxiety. Part of abstract reasoning includes being able to take an observer perspective on one's self and to make inferences about other people's thoughts and feelings. Although the emergence of abstract reasoning is ultimately a useful tool that allows adults to self regulate, in adolescence, it might contribute to higher vulnerability to social anxiety and other emotional disorders, says Rosso. "In adolescence, you start to become more self aware, and more able to think abstractly or hypothetically about other people's thoughts and feelings," says Rosso. "But that may also allow you to have more social self consciousness, and worry more about what other people are thinking about you. It may open up new vulnerabilities in some adolescents."
The current intrauterine devices (IUD) are small devices, often 'T'-shaped, often containing either copper or levonorgestrel, which are inserted into the uterus. They are one form of long-acting reversible contraception which are the most effective types of reversible birth control.  Failure rates with the copper IUD is about % while the levonorgestrel IUD has a failure rates of % in the first year of use.  Among types of birth control, they along with birth control implants result in the greatest satisfaction among users.  As of 2007, IUDs are the most widely used form of reversible contraception, with more than 180 million users worldwide. 
Calories are a way of measuring energy – the amount of energy that your body gets from eating that food. Your body needs a certain amount of energy every day to keep it going - things like keeping your muscles moving, your heart beating, your body heated and your brain ticking. The energy comes from the food and drink that you consume. If you eat and drink just the right amount (with the right amount of calories in them) to move your muscles, work your brain etc then you won't get over or underweight. Eating too many calories in your food turns it into fat; eat too few and you begin to disappear.