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Physics-Informed Optimization Methods of Metasurface and Reconfigurable Antenna Inverse Design for Intelligent Sensing and Imaging Systems
No full textAdvances in metasurface inverse design have the potential to revolutionize intelligent sensing and imaging systems by leveraging computational optimization and machine learning. This thesis presents a unified exploration of physics-informed optimization techniques applied across three distinct works, each addressing a critical aspect of modern engineering challenges. Specifically, we explore the inverse design of meta- surfaces, from the RF domain to the visible range, uniting the fields of wireless com- munication and optical imaging. Chapter 2 introduces a novel approach to the inverse design of GHz reconfigurable antennas using physics-informed graph neural networks, enabling intelligent beam-forming. Chapter 3 delves into the optimization of a multi- layer broadband metalens for dual-functional color-sorting and polarization imaging, demonstrating significant improvements in optical efficiency and functionality. And Chapter 4 transitions to high resolution 3D imaging, presenting a neural single-shot GHz FMCW correlation imaging system that achieves absolute depth reconstruction with high precision. Together, these works illustrate the versatility and impact of physics-informed optimization, uniting computational design and physics priors to push the boundaries of metasurface technologies and beyond
Limited Feedback Models in Online Control
No full textThe study of online control of linear dynamical systems has attracted increasing interests within the machine learning community. This framework generalizes the classical control theory by relaxing assumptions on the cost and perturbation models. However, even under these relaxed assumptions, full information feedback remains impractical in many settings. This thesis addresses this limitation by exploring online control models with restricted feedback, with a focus on the bandit feedback setting. We contribute efficient algorithms for bandit convex optimization that achieve tight regret guarantees. Subsequently, these results lead to development of novel bandit controller algorithms that push toward optimal rates under minimal assumptions on the cost function class and noise model. Along the way, we also present results in controlling marginally stable systems and offer contributions to other problems in online learning, such as uncertainty quantification in matrix completion and memory- efficient covariance sketching
ANTIMICROBIAL PROTECTION OF MARSUPIAL NEWBORNS
No full textThe transition from the sterile maternal womb to microbe-rich extrauterine environments presents immunological challenges to mammalian newborns. Born with underdeveloped immune tissues, marsupial neonates require specialized immunological protections from microbial pathogens. However, exact identity and the composition of the protective immune cells and compounds expressed by marsupial neonates remain unknown. Here, combining transcriptomic, epigenomic, functional assays, and comparative genomics, we have investigated immunological defense strategies of marsupial neonates using the sugar glider (Petaurus breviceps) as a model. We have identified neutrophils and cathelicidin genes as a key cell type and key genes in marsupial newborns. Further transcriptomic and proteomic analyses have detected the expression of cathelicidins in multiple hematopoietic tissues as well as in the maternal milk. Through syntenic analyses, we discovered that sugar glider cathelicidin genes reside in two genomic clusters and that marsupials and monotremes are the only tetrapods that retained two cathelicidin gene clusters while eutherians and non-mammalian tetrapods possess only one cluster. Subsequent epigenomic analyses have shown that the coordinated expression of cathelicidin genes across two clusters is achieved by enhancer sharing within clusters and long-range physical interactions between clusters. Finally, in vitro and in vivo immunological asssays have discovered the direct antimicrobial activity as well as the immunomodulatory properties of multiple cathelicidin genes. By wholistically characterizing the evolution, regulation, and function of the cathelicidin gene family, our results identified the key mediator of the marsupial neonatal immune protection
ASPECTS OF WILSON LOOPS AND MINIMAL SURFACES IN ADS/CFT
No full textWith an eye towards better understanding the AdS/CFT correspondence, in this thesis we study the 1d defect conformal field theory (CFT) living on the half-BPS Wilson line in N=4 Super Yang-Mills and its dual description via the AdS2 string in AdS5xS5. The first half of the thesis, based on work with Simone Giombi, Shota Komatsu and Jieru Shan, develops the formalism for computing boundary correlators on the AdS2 string in conformal gauge and explores its consequences. A key role is played by the boundary reparameterization mode that maps the worldsheet boundary coordinate to the target space coordinate along the Wilson line and whose practical effect is to mediate interactions between transverse fluctuations of the string. We determine its effective action to cubic order in a saddle point expansion and compute the tree-level four- and six-point boundary correlators, which match results in static gauge. We also use the reparameterization mode to study the out-of-time-order correlators (OTOCs), both at leading order via analytic continuation and to all orders in a double-scaling limit by resumming a relevant subset of diagrams. These methods nicely complement analyses of the OTOCs in terms of scattering processes on the worldsheet or geodesics on the worldsheet with shockwaves.
The second half of the thesis, based on work with Simone Giombi and Shota Komatsu, examines a large charge sector of the Wilson line defect CFT. We analyze defect correlators of two large charge insertions and several light insertions using both supersymmetric localization and their dual description as expectation values of light vertex operators on a classical string spinning in S5. We also study quantum fluctuations of the spinning string and compute the correlation function of two large charge and two light insertions in terms of Green's functions on the worldsheet, which we use to extract CFT data for a tower of operators on the defect
Aristotle on Eggs
No full textA key issue for commentators on Aristotle’s embryology is the problem of “wind-eggs,” unfertilized eggs produced by some female birds or fish without male insemination, to which Aristotle assigns some degree of soul in Generation of Animals (GA) 2.5: nutritive soul in potentiality, which allows them to grow. This seemingly contradicts his hylomorphic doctrine that the male provides the form or soul to the new animal being generated, by providing the moving cause of generation, whereas the female provides the matter, the material cause.
This dissertation argues that when Aristotle’s comments on wind-eggs are placed in the context of his account of how egg-laying animals reproduce, they do not contradict his commitment to the view that only the male animal can initiate new life (by serving as the moving cause that initiates the actualization of form in the matter). The dissertation reconstructs Aristotle’s account of oviparous generation from GA 3, showing that he distinguishes between the production of an egg and the subsequent conception of the embryo that develops inside the egg. Eggs are uterus-analogues for Aristotle; I argue that this means they should in fact be understood as parts of the animal who lays them. Following Aristotle’s functional view of body parts, we can understand him to attribute soul to wind-eggs not because they are early, defective embryos, but because they are parts of an ensouled whole, potentially able to perform a reproductive function for the egg-layer.
Aristotle’s hylomorphic theory of generation presented in the rest of GA is therefore not destabilized by his comments on wind-eggs, and his association of the male with soul and activity and the female with matter and passivity remains in place. One upshot of this interpretation of wind-eggs is that it reveals how Aristotle’s mereology can allow for living wholes to have physically disconnected parts that still share in the life of the whole for a time. Correspondingly, we see how the generation of egg-laying animals is a less physically unified process than that of live-bearing animals, reflecting one way that Aristotle’s hierarchy of living beings comes into play in his biological thought
Sociological Formalism, Or How Formalism was Made and Remade
No full textBy “Russian Formalism”, scholars refer to the literary theory developed between the mid-1910s and the late 1920s by a group of scholars and writers, including Viktor Shklovsky, Boris Eikhenbaum, and Yury Tynianov. As the theory posited that literature cannot be reduced to the context where it is produced, it fell victim to the criticism of the growingly intolerant Sovietregime in the 1930s. The Formalists’ works and ideas started being discovered in the West in the 1950s and early 1960s before they were allowed to reappear in the mid-1960s in the Soviet Union. My dissertation, “Sociological Formalism, Or How Formalism Was Made and Remade” uses archival material collected in the United States, Italy, the Netherlands, and Russia to provide a rigorous account of the networks (publishers, patrons, scholars, translators) that made the (re)appearance of works on Formalism materially possible in the USA, France, Germany, Italy and the Soviet Union, and studies the narratives shaping the circulation of these ideas.
In chapter 1, I reconstruct the publication of Victor Erlich’s Russian Formalism. History-Doctrine (1955), the first monograph on Formalism to appear in a Western country. Thanks to archival materials, I reconstruct the history of the publication and argue that the monograph develops a bipartite plot severing Formalism from the Soviet context by presenting it as a
predecessor to the all-encompassing structuralist theories of Roman Jakobson, René Wellek, and Austin Warren. Chapter 2 follows the subsequent developments of this narrative, in the USA and several European countries between 1955 and 1972. Chapter 3 and 4 move away from the academic context. In the former, I show how a surprising number of translations from the Formalists appeared in Italy between 1965 and 1969 thanks to two distinct networks, one orbiting around the publisher De Donato Editore, and the other connected to the Communist journal “Rassegna Sovietica”. The final chapter moves to the Soviet context of the 1960s and investigates how the scholarly legacy of Tynianov was rehabilitated thanks to the possibilities afforded by the post-stalinist biographical genre
