Ptychography Coherent Diffractive Imaging Systems For Extreme Ultraviolet and X-Ray Sources

Ptychography coherent diffractive imaging is a rapidly developing method for microscopic imaging with coherent X-ray and extreme ultraviolet sources. The technique, which shifts the role of image formation from a physical optic to a computational algorithm, provides a route toward photon efficient imaging systems with diffraction-limited resolution. When combined with high-energy coherent light sources, a microscope capable of probing the nanoworld with exquisite elemental and chemical sensitivity is realized. However, these systems come with concessions such as the large data volume required to form an image, long data acquisition times, and relatively complex image reconstruction methods. This thesis focuses on the development and extension of ptychography coherent diffractive imaging to higher throughput modalities. This is demonstrated with the formulation of the multiple beam ptychography method that uses several beams to simultaneously probe different parts of a sample. This is first shown with beams of different wavelengths and later with different polarization states. The technique is then extended for beams with identical wavelengths and polarizations by controlling the aliasing of the measured signal. Finally, an X-ray spectromicroscopy study of a highly heterogeneous meteoric grain is discussed. Ptychography coherent diffractive imaging is combined with scanning transmission X-ray microscopy and X-ray absorption spectroscopy to reveal the meteorite&rsquo;s mineralogical properties through chemical, elemental, and textural identification with a resolution more than an order of magnitude lower than previous similar studies.</p

Origins of antisocial behavior. Negative reinforcement and affect dysregulation of behavior as socialization mechanisms in family interaction

Click on the DOI link below to access the article (may not be free).Theoretical models specifying the contribution of two social-familial mechanisms, negative reinforcement and affect dysregulation, to the development of child antisocial behavior were tested using a sample of 57 8- to 13-year-old boys referred for treatment of conduct problems. Negative reinforcement of boys' aggressive behavior and boys' affect dysregulation were found to covary with the boys' irritability toward parents and siblings and were reliable predictors of a composite measure of child antisocial behavior, defined by out-of-home placement, arrests, and school discipline incidents 2 years later. Reinforcement of aggression and affect dysregulation during family interaction may play complementary roles in the development of antisocial behavior by fostering the use of coercive means of dealing with social conflict. The findings are discussed in terms of research strategies for identifying social mechanisms contributing to child psychopathology and of implications for modification of current family interventions targeting child antisocial behavior.NIMH NIH HHSpeer reviewe