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ALL-OPTICAL REGENERATION FOR PHASE-SHIFT KEYED OPTICAL COMMUNICATION SYSTEMS
Title
ALL-OPTICAL REGENERATION FOR PHASE-SHIFT KEYED OPTICAL COMMUNICATION SYSTEMS.
Creator
Croussore, Kevin, Li, Guifang, University of Central Florida
Abstract / Description
All-optical signal processing techniques for phase-shift keyed (PSK) systems were developed theoretically and demonstrated experimentally. Nonlinear optical effects in fibers, in particular four-wave mixing (FWM) that occurs via the ultra-fast Kerr nonlinearity, offer a flexible framework within which numerous signal processing functions can be accomplished. This research has focused on the regenerative capabilities of various FWM configurations in the context of processing PSK signals. Phase...
Show moreAll-optical signal processing techniques for phase-shift keyed (PSK) systems were developed theoretically and demonstrated experimentally. Nonlinear optical effects in fibers, in particular four-wave mixing (FWM) that occurs via the ultra-fast Kerr nonlinearity, offer a flexible framework within which numerous signal processing functions can be accomplished. This research has focused on the regenerative capabilities of various FWM configurations in the context of processing PSK signals. Phase-preserving amplitude regeneration, phase regeneration, and phase-regenerative wavelength conversion are analyzed and demonstrated experimentally. The single-pump phase-conjugation process was used to regenerate RZ-DPSK pulse amplitudes with different input noise distributions, and the impact on output phase characteristics was studied. Experiments revealed a limited range over which amplitude noise could effectively be suppressed without introduction of phase noise, particularly for signals with intensity pattern effects. Phase regeneration requires use of phase-sensitive amplification (PSA), which occurs in nonlinear interferometers when the pump and signal frequencies are degenerate (NI-PSA), or in fiber directly through single-stage (degenerate) or cascaded (non-degenerate) FWM processes. A PSA based on a Sagnac interferometer provided the first experimental demonstration of DPSK phase and amplitude regeneration. The phase-regenerative capabilities of the NI-PSA are limited in practice by intrinsic noise conversion (amplitude to phase noise) and to a lesser extent by the requirement to modulate the pump wave to suppress stimulated Brillouin scattering (SBS). These limitations are relaxed in novel materials with higher SBS thresholds and nonlinearities. Degenerate FWM provides PSA in a traveling-wave configuration that intrinsically suppresses the noise conversion affecting the NI-PSA, while providing stronger phase-matched gain. Experiments confirmed superior phase-regenerative behavior to the NI-PSA with simultaneous reduction of amplitude noise for NRZ-DPSK signals. Phase-regenerative wavelength conversion (PR-WC) provides the regenerative properties of PSA at a new wavelength, and was proposed and demonstrated for the first time in this research. The parallel implementation of two FWM processes, phase-conjugation and frequency conversion, provides two idlers which exhibit interesting and useful regenerative properties. These were investigated theoretically and experimentally. Ideal phase-regenerative behavior is predicted when the contributing FWM processes are equally phase-matched, which can be maintained over any interaction length or wavelength shift provided the pump powers are properly adjusted. Depleted-pump regime PR-WC provides simultaneous phase and amplitude regeneration. Experiments confirmed regenerative behavior for wavelength shifts of the idlers up to 5 nm. Two techniques for phase regeneration of 4-level PSK signals were developed and evaluated. The first is based on parallel operation of PSAs suitable for processing 2-level PSK signals, where phase projection and regeneration are combined to recover the input data. Analysis of this scheme outlined the conditions required for effective phase regeneration and for practical implementation using known PSAs. A novel process based on FWM (parallel phase-conjugation followed by PSA) was developed and analyzed, and demonstrated using numerical simulations. These studies provide a basis for further work in this area.
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Date Issued
2007
Identifier
CFE0001923, ucf:47473
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0001923
Embryonic Stem Cell Derived Exosomes Enhance Cardiac Stem Cell Differentiation into Heart Cells
Title
Embryonic Stem Cell Derived Exosomes Enhance Cardiac Stem Cell Differentiation into Heart Cells.
Creator
Hammond, Jamillah, Singla, Dinender, Masternak, Michal, Davidson, Victor, University of Central Florida
Abstract / Description
Transplantation of embryonic stem (ES) cells into the ischemic and infarcted heart has proven to repopulate cardiac cell populations, attenuate structural cardiac remodeling, and rescue cardiac function. Unfortunately, the pluripotency of ES cells increases risk of teratoma formation in vivo. Exosomes, smaller in comparison to ES cells, are cell free carriers of miRNA, proteins, and lipids, and do not suggest risk of teratoma formation. Exosomes have been proposed to mediate and attenuate...
Show moreTransplantation of embryonic stem (ES) cells into the ischemic and infarcted heart has proven to repopulate cardiac cell populations, attenuate structural cardiac remodeling, and rescue cardiac function. Unfortunately, the pluripotency of ES cells increases risk of teratoma formation in vivo. Exosomes, smaller in comparison to ES cells, are cell free carriers of miRNA, proteins, and lipids, and do not suggest risk of teratoma formation. Exosomes have been proposed to mediate and attenuate regeneration following myocardial infarction (MI), however, the role of exosomes derived from ES cells (ES-Exo) in activating resident cardiac stem cells (CSCs) to undergo cardiac differentiation is not established. In the present study, Stem cell antigen 1 positive (Sca-1+ve) CSCs were isolated, incubated with exosomes, and evaluated for differentiation into the major heart cell types in vitro. Observations of in vitro cardiac differentiation were further established in an in vivo model of MI. Ligation of the coronary artery, or a sham surgery was performed in C57BL/6 mice 8-12 weeks of age. Mice were split among four study groups: sham, MI, MI + H9c2-Exo (a cell line control), (&) MI + ES-Exo. ES-Exo were transplanted via intramyocardial (IM) injection immediately following coronary artery ligation. At day 14 (D14), echocardiography was used to evaluate cardiac function. Differentiation into the major heart cells was determined by sarcomeric ?-actin (cardiomyocytes) and smooth muscle ?-actin (vascular smooth muscle cells) immunostaining. Hematoxylin and Eosin and Masson's Trichrome staining assessed cardiomyocyte hypertrophy and fibrosis, respectively. Immunostaining for major heart cellular markers revealed significant activation of resident Sca-1+ve CSCs to undergo cardiac differentiation after ES-Exo treatment. Cardiomyocyte hypertrophy and myocardial fibrosis were significantly increased following coronary artery ligation. Results from histological staining revealed significantly decreased levels of hypertrophy and fibrosis in hearts transplanted with ES-Exo following coronary ligation. In summary, our findings advocate ES-Exo as a viable treatment option to repopulate the myocardium with viable heart cells, attenuate cardiac remodeling, and rescue cardiac function.
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Date Issued
2018
Identifier
CFE0007188, ucf:52254
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0007188
Development of a Functional In Vitro 3D Model of the Peripheral Nerve
Title
Development of a Functional In Vitro 3D Model of the Peripheral Nerve.
Creator
Anderson, Wesley, Lambert, Stephen, Hickman, James, Fernandez-Valle, Cristina, Willenberg, Bradley, University of Central Florida
Abstract / Description
Peripheral neuropathies, affect approximately 20 million people in the United States and are often a complication of conditions such as diabetes that can result in amputation of affected areas such as the feet and toes. In vitro methodologies to facilitate the understanding and treatment of these disorders often lack the cellular and functional complexity required to accurately model peripheral neuropathies. In particular, they are often 2-D and functional readouts, such as electrical...
Show morePeripheral neuropathies, affect approximately 20 million people in the United States and are often a complication of conditions such as diabetes that can result in amputation of affected areas such as the feet and toes. In vitro methodologies to facilitate the understanding and treatment of these disorders often lack the cellular and functional complexity required to accurately model peripheral neuropathies. In particular, they are often 2-D and functional readouts, such as electrical activity, are limited to cell bodies thereby limiting the understanding of axonopathy which often characterizes these disorders. We have developed a functional 3-D model of peripheral nerves using a capillary alginate gel (Capgel(TM)), as a scaffold. We hypothesize that: 1) The unique microcapillary structure of Capgel(TM) allows for the modeling of the 3-D microstructure of the peripheral nerve, and 2) That axon bundling in the capillary allows for the detection of axonal electrical activity. In our initial studies, we demonstrate that culturing embryonic dorsal root ganglia (DRG) within the Capgel(TM) environment allows for the separation of cell bodies from axons and recreates many of the features of an in vivo peripheral nerve fascicle including myelinated axons and the formation of a rudimentary perineurium. To develop functionality for this model we have integrated the DRG Capgel(TM) culture with a microelectrode array to examine spontaneous activity in axon bundles, which we find demonstrates superiority to other widely used 2-D models of the same tissue. Furthermore, by analyzing the activity on individual electrodes, we were able to record action potentials from multiple axons within the same bundle indicating a functional complexity comparable to that observed in fascicles in vivo. This 3D model of the peripheral nerve can be used to study the functional complexities of peripheral neuropathies and nerve regeneration as well as being utilized in the development of novel therapeutics.
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Date Issued
2018
Identifier
CFE0007150, ucf:52303
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0007150
CRISIS, SHELL-SHOCK, AND THE TEMPORALITY OF TRAUMA: CULTURAL MEMORY AND THE GREAT WAR COMBATANT EXPERIENCE IN OWEN, GRAVES, AND BARKER
Title
CRISIS, SHELL-SHOCK, AND THE TEMPORALITY OF TRAUMA: CULTURAL MEMORY AND THE GREAT WAR COMBATANT EXPERIENCE IN OWEN, GRAVES, AND BARKER.
Creator
Kelly, Dylan, Grajeda, Anthony, University of Central Florida
Abstract / Description
The year 2014 will mark the centennial of the outbreak of World War I in August 1914. This historic anniversary will likely provoke several discussions from all fields in the humanities concerning the Great War's significance on contemporary culture through history, visual art, and in the case of this essay: literature. In light of this event, any serious discussion among scholars should undeniably begin with how the war continues to be represented today through a thorough, contemporary...
Show moreThe year 2014 will mark the centennial of the outbreak of World War I in August 1914. This historic anniversary will likely provoke several discussions from all fields in the humanities concerning the Great War's significance on contemporary culture through history, visual art, and in the case of this essay: literature. In light of this event, any serious discussion among scholars should undeniably begin with how the war continues to be represented today through a thorough, contemporary analysis of its many key literary texts. This thesis will examine, in this regard, how past and contemporary discourses in literary theory—primarily concerned with how an individual combatant subject attempts to construct and understand their own traumatic experiences through poetic and literary discourse—can continue to incite discussion on why literature of the Great War and its influential role in defining how it has come to be understood in our cultural memory remains relevant even today. Under the guiding influence of Paul Fussell's classic The Great War and Modern Memory, I will discuss how three important works—a poetry collection, a memoir, and a modern work of historical fiction—all contribute to how the war has become represented as a tragic rupture in history that reversed the idea of human progress and left an entire generation disillusioned in its aftermath, regardless of the historical veracity of this legacy. The texts I will be examining include: select poems of Wilfred Owen, Goodbye to All That by Robert Graves, and Regeneration by Pat Barker. In addition to this, I will conclude with an analysis of how a contemporary reading of these texts can contribute to a larger discussion of the crisis of historicity in our current post-modern cultural landscape.
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Date Issued
2014
Identifier
CFH0004557, ucf:45210
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFH0004557