The lack of such documentation led many scientists to challenge the government's assertion in the late 1970's and early 1980's that the Soviet Union had dropped unknown toxic weapons in Southeast Asia and on Afghans.
For many scientists, this is challenging.
B1 NEEDIEST CASES B7 SCIENCE TIMES F1-12 We May Be Alone "Rare Earth," a book by two prominent scientists, challenges the conventional wisdom that there are probably many alien civilizations.
Many scientists and physicists have challenged it, including MIT physicist Max Tegmark, who wrote a paper in 2000 that was widely cited.
Many scientists take on this challenge with enthusiasm and energy; some with great skill.
That view has been challenged by many scientists.
It has been a great challenge for many scientists and engineers to compute elastic plastic solutions for dynamically loaded cracked structures due to the fact that the solutions are much more complicated and computationally time consuming than corresponding static problems.
Due to their inherited properties, (i.e. spareness, non-stationarity or cyclostationarity, wide-band frequency range, wide range of power, etc)., the process of underwater acoustic signals becomes a real challenge for many scientists and engineers who are involved in studies related to the ocean.
"That is really the greatest challenge, because many scientists can come up with new materials for certain applications, … but if they don't know how these materials are going to be placed in the body and interact with the cells, interact with biological fluids and so on, they have no appreciation of the total problem," Peppas says.
Many scientists have pointed out this challenge [ 6, 7], but to our knowledge, no systematic research has been done in this field.
