It is also possible to use multiple active elements and combine them together with transmission lines to produce a similar system where the phases add up to reinforce the output. The antenna array and very similar reflective array antenna consist of multiple elements, often half-wave dipoles, spaced out on a plane and wired together with transmission lines with specific phase lengths to produce a single in-phase signal at the output. The log-periodic antenna is a more complex design that uses multiple in-line elements similar in appearance to the Yagi-Uda but using transmission lines between the elements to produce the output.
What is the most common element used to create a single in phase signal?
half-wave dipoles

The final chapter reviews points from earlier chapters, and Darwin concludes by hoping that his theory might produce revolutionary changes in many fields of natural history. Although he avoids the controversial topic of human origins in the rest of the book so as not to prejudice readers against his theory, here he ventures a cautious hint that psychology would be put on a new foundation and that "Light will be thrown on the origin of man". Darwin ends with a passage that became well known and much quoted:
What does Darwin allude to hoping in the final chapter of On the Origin of Species about humans?
that psychology would be put on a new foundation and that "Light will be thrown on the origin of man"

In the first three seasons, the semi-finalists were split into different groups to perform individually in their respective night. In season one, there were three groups of ten, with the top three contestants from each group making the finals. In seasons two and three, there were four groups of eight, and the top two of each selected. These seasons also featured a wildcard round, where contestants who failed to qualify were given another chance. In season one, only one wildcard contestant was chosen by the judges, giving a total of ten finalists. In seasons two and three, each of the three judges championed one contestant with the public advancing a fourth into the finals, making 12 finalists in all.
How were the semi-finalists split up to perform in seasons two and three?
four groups of eight