Implausible projects that could not have been done by kids:
"A Study of the Endogenous Activity Rhythms of the Marine Isopod Exosphaeroma truncatitelson" Where does a kid get that and the testing environment necessary?
"Analysis of Photon-Mediated Entanglement between Distinguishable Matter Qubits" Oh come on. Well I'll head on over to home depot and get a can of qubits on the way home from school, and then...
"DNA Repair Mechanisms: Investigations of Base Excision Repair Pathway in Differentiated and Proliferative Neuronal CAD Cells" Oh come on. How big was the lab that did this work? 50 people and 10 million bucks of gear maybe?
"Synthesis of Trimethylguanosine Cap Analogues with the Potential Use in Gene Therapy" Oh come on
"Synthesis of Triazene Compounds and Their Application in Spectrophotometric Determination of Cadmium" Nobody's doing cadmium work outside a lab, at least without turning the basement into a "radioactive boyscout" situation. I would promote this to "possible" if and only if it were done as independent study at a high school chem lab.
Amir, I work at the sponsoring company so I've been exposed to a lot of the contestants @ the regional level. A few comments:
1) Most of these top tier kids @ the international level are really geniuses. We're talking way beyond perfect GPAs & SAT scores. In other words, they have the brain power to make a breakthrough with proper direction.
2) Select high schools with science fair magnet programs work in conjunction with local colleges & research labs. Ideas like the ones you list above often come from frequent interaction with experts in the field (at other science fairs, as a guest speaker @ the science magnet program, etc.). As you said, high schools do not have the facilities for some of these projects. Any papers, patents, and IP are typically owned by the sponsoring college/lab (student gets primary author kudos).
3) The dynamic should be viewed more as a professor / PhD candidate. The PhD candidiate typically has not pulled his/her idea out of thin air... they often build upon existing work in the professor's field. A similar style of interaction is used on these science fair projects. It often takes months for the student to come up with the actual experiment; it's not the prof saying "hey, why don't you do these measurements for me". If you talk to these kids, it is clear that they did most of the work.
4) Often a successful (i.e. award winning) project is the students 2nd or 3rd project that they did @ that lab or the result of multiple years of research. They don't get to waltz into a lab and start playing with a $$$ piece of hardware.