RESUMO
Atom interferometers covering macroscopic domains of space-time are a spectacular manifestation of the wave nature of matter. Because of their unique coherence properties, Bose-Einstein condensates are ideal sources for an atom interferometer in extended free fall. In this Letter we report on the realization of an asymmetric Mach-Zehnder interferometer operated with a Bose-Einstein condensate in microgravity. The resulting interference pattern is similar to the one in the far field of a double slit and shows a linear scaling with the time the wave packets expand. We employ delta-kick cooling in order to enhance the signal and extend our atom interferometer. Our experiments demonstrate the high potential of interferometers operated with quantum gases for probing the fundamental concepts of quantum mechanics and general relativity.
RESUMO
The epidermal growth factor receptor (EGFR) gene is amplified in 40% of malignant gliomas, and the amplified genes are frequently rearranged. We have characterized the genetic alterations associated with these rearrangements in five malignant gliomas. In one tumor the rearrangement resulted in the deletion of most of the extracytoplasmic domain of the receptor, resulting in a hybrid mRNA between new sequences and the truncated EGFR sequence. The predicted amino acid sequence of the protein from this tumor was remarkably similar to that described for several viral erbB oncogenes. Four other tumors were noted to have internal deletions of the EGFR gene. These rearrangements brought about in-frame deletions affecting either of two cysteine-rich domains in the extracytoplasmic portion of the molecule. The clonal nature of these alterations, and the fact that identical alterations were seen in more than one tumor, suggests a role for these mutant receptor proteins in tumorigenesis. Further, these studies document the existence of tumor-specific cell surface molecules resulting from somatic mutation.
