Browsing by Subject "Imaging"
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Item Neural Correlates of the Relationship between Optimism and Pain Perception in a Conditioned Pain Modulation Paradigm(2018-01-01) Hinkle, Caroline Elizabeth; Quiton, Raimi L; Psychology; PsychologyIntroduction: Pain is a pervasive public health problem in the United States. Despite its prevalence, the variables influencing pain processing remain poorly understood. It is now accepted that psychological factors such as optimism have the potential to influence both clinical and experimental pain outcomes. It has been suggested that people in high in optimism may modulate pain more effectively. However, the neural mechanisms of this relationship have not been explored. Method: Participants underwent psychophysical testing using a conditioned pain modulation (CPM) paradigm, a common measure of endogenous pain modulation. Participants rated a series of painful heat test stimuli alone and then again in the presence of a painful pressure conditioning stimulus.Participants typically rate the test stimuli as less painful in the presence of the conditioning stimulus, a phenomenon known as "pain inhibits pain” or CPM. Participants repeated the CPM paradigm in a separate session during a functional MRI scan. A measure of dispositional optimism was administered before the scan. Results: Imaging results showed that greater dispositional optimism was associated with increased heat-pain related brain activity in areas involved in sensory pain processing, including the somatosensory cortex, superior parietal lobe, and posterior insula. Optimism was also positively associated with activity in sensory brain areas during CPM stimulation, including in the superior parietal lobe, somatosensory cortex, and supramarginal gyrus. Additionally, during CPM stimulation, optimism was negatively associated with activity in brain areas implicated in gating attention to pain, including the dorsolateral prefrontal cortex. Conclusion: Optimism may modulate differences in pain perception via attention and sensory awareness, whereby greater attention to painful stimuli causes increased perception of pain intensity.Item Non-Invasive Imaging of Object Behind Scattering Media via Cross-Spectrum(IEEE, 2022-05-10) Zhao, Xingchen; Peng, Tao; Zhang, Lida; Zubairy, M. Suhail; Shih, Yanhua; Scully, Marlan O.We develop a method based on the cross-spectrum of an intensity-modulated CW laser, which can extract a signal from an extremely noisy environment and image objects hidden in scattering media. We theoretically analyzed our scheme and performed the experiment by scanning the object placed in between two ground glass diffusers. The image of the object is retrieved by collecting the amplitudes at the modulation frequency of all the cross-spectra. Our method is non-invasive, easy-to-implement, and can work for both static and dynamic media.Item Transverse Correlation in Entangled Photons and Light-Matter Interaction(2007-07-12) Wen, Jianming; Rubin, Morton H.; Physics; Physics, AppliedIn recent years, quantum entanglement has attracted much; attention, because its unique properties provide potential; applications, which could not be achieved using conventional; techniques, such as quantum computing, quantum imaging and; lithography. To realize these advancements, one has to obtain an; entanglement-generation source, thoroughly master its physical; properties, and fully understand the light-matter interaction.; This dissertation is an attempt to address such issues as stated; above.; Conventionally, paired photons are created from; \textit{spontaneous parametric down-conversion} (SPDC). It is; known that the transverse correlation in biphotons may improve the; visibility and resolution in quantum imaging and lithography. In; this thesis, we described an alternative biphoton source --; Raman-EIT (\textit{electromagnetically induced transparency}); generator, and emphasize on its geometrical and optical; properties. We found that to utilize the transverse effects in; paired Stokes-anti-Stokes, it is necessary to make the product of; the EIT window times the group delay much greater than unity.; To gain further insight into quantum imaging and lithography, we; studied the transverse correlation in triphoton entanglement; theoretically. We found that in the two-image process, the quality; of images is determined by the optical path-lengths, even though; the Gaussian thin lens equations are satisfied. The ghost; interference-diffraction patterns of double slits show one more; fold interference, which is essentially different from the; biphoton case. Klyshko's advanced-wave model is still applicable,; with some modifications. We also generalized the transverse; correlation to the case of multi-photon entangled states.; To implement quantum computing, one key element is quantum memory.; In this thesis, we have theoretically explored the feasibility of; such a memory by using nonclassical SPDC light in an EIT system at; the single-photon level. We found that both the quantum coherence; of SPDC and atomic coherence of EIT can survive after interacting; within a vapor cell. Due to the inherent mismatch of magnitude; between the spectral bandwidth of SPDC and the very narrow; transmission width of EIT, the coincidence counts of the; two-photon interference is reduced to one pair per second, which; is barely doable in the current experimental situation.