We report an inelastic (Raman) light scattering study on bulk crystalline GeTe (c-GeTe) and amorphous GeTe (a-GeTe) thin films and found to show pronounced similarities in local structure between the two states. In c-GeTe, the observed Raman modes represent the Ge atoms are in three different environments, namely, tetrahedral, distorted, and defective octahedral sites. On the other hand, in a-GeTe, Raman spectrum reveals Ge sites in tetrahedral and defective octahedral environment. We suggest that the structure of c-GeTe consists of highly distorted as well as defective Ge sites, which leads to the large concentration of intrinsic defects (vacancies). These random defects would act as topological disorder in the lattice and cause the bands to develop tails at the band edges, a continuum of localized levels appearing in the gap. The present study deepens the understanding of the local atomic structure, influence of defects and its close relation to the phase-change mechanism.
Social media is used by patients for health care information. We analyzed the quality of YouTube videos on prostate cancer screening. Most videos (71.1%) mentioned the potential harms of prostate cancer screening. There was no significant difference in risk-related information between videos published before and after the publication of US Preventive Services Task Force 2012 guidelines for prostate cancer screening. In conclusion, the quality of information of YouTube videos on prostate cancer screening is low and the content is potentially misleading.
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