Snowflake in the same micro-environment does not guarantee that each arm grow the same; indeed, for some crystal forms it does not because the underlying crystal growth mechanism also affects how fast each surface region of a crystal grows. Empirical studies suggest less than 0.1% of snowflakes exhibit the ideal six-fold symmetric shape. Very occasionally twelve branched snowflakes are observed; they maintain the six-fold symmetry. Snowflakes form in a wide variety of intricate shapes, leading to the notion that "no two are alike". Although nearly-identical snowflakes have been made in laboratory, they are very unlikely to be found in nature. Initial
How to Have Sex in an Epidemic to those with a lower risk of contagion. It was a model that attempted to challenge traditional anti-promiscuity and anti-gay viewpoints in previous safe sex education and AIDS prevention—as Callen and Berkowitz argued, it's what you do, not how often you do it or who you do it with. In other words, they had searched for, and come up with, what they termed the possibility of "life-affirming sex." The categories below contain summaries of the chapters of "How to Have Sex in an Epidemic" and the arguments presented therein: The authors introduce the two presiding theories of AIDS transmission and