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Affective Representation and Infrastructure in Allan Sekula's Fish Story, 1989-2017
Get PDFIn 1989, contemporary American artist Allan Sekula (1951–2013) embarked on a seafaring project to document transnational seaports which would later be published as the iconic Fish Story (1989–1995). His personal notebooks during this voyage (among other several materials) would later be acquired by the Getty Research Institute in 2017 and turned into an archive. Fish Story would become perhaps Sekula’s most influential work. Sekula, a dedicated Marxist with highly influential commentary on globalization and capitalism (most of which arose through the medium of documentary photography and critical writing) directly confronted the mechanisms that allowed ports and sea-faring technologies to conduct profound capitalist processes, ultimately finding the entire system to be dangerously elusive. Sekula’s life and work is primarily handled within the fields of contemporary art history and criticism (with particular attention toward his sociocritical and historical work on photographic representation) but because of infrastructure studies’ continued integration of visual studies, he deserves more attention within the annals of the history of technology. Within scholarship on the history of technology we can find immediate relevance in his work that engaged with the themes of containerization and the methodological framework of infrastructural inversion. But, unlike what scholarship has settled for Sekula, it is the aim of this paper to cement his agency within infrastructure studies through an affectual approach. This will be done by surveying Sekula’s “sympathetic” documentary tendencies in relation to his experiences with infrastructural networks during the Fish Story voyage, the accounts of which are mainly mined from his personal notebooks. For clarity, the analysis splits up the survey of Sekula’s interaction with infrastructure into a pair: emotional and biographical narratives and representational and photographic theory and history. Near the end, the paper also incorporates recent scholarship Sekula’s archival practices and methods. Overall, this sort of techno-biographical survey of Sekula will showcase the tremendous relevance of a contemporary artist to the history of technology
Fragmentación y marginalidad del sujeto femenino en cinco obras de Juan Radrigán
Get PDFEl teatro de Juan Radrigán se presenta como una evidencia de la realidad chilena durante los años de la dictadura militar vivida en Chile bajo el control del General Augusto Pinochet.
Dentro de las obras teatrales de Radrigán se aprecia la construcción de sujetos femeninos que escapan de la imagen típica del "ángel del hogar", mostrándose como seres complejos con identidades propias que se ven afectados por las situación que se vivió Chile durante el periodo de la dictadura militar
Molecular beam epitaxial growth of interband cascade structures with advances in InAs- and GaSb-based interband cascade lasers
Get PDFInterband cascade lasers (ICLs) based on the type-II quantum well (QW) active region have attracted much interest over the years, in large part due to their low power consumption. Their operation hinges on two key features; interband transitions in type-II quantum wells and a cascade configuration which enhances the gain, per current density. The cascade configuration forms an energy staircase where an injected electron recombines with a hole within the active region of a single cascade stage to generate a photon, and is then quickly swept into the next cascade stage, where the same process may occur. In this way, each injected electron may generate a photon for every cascade stage it travels through, allowing for quantum efficiencies that exceed the conventional limit of unity. The overall ICL structure is built from a combination of multiple superlattice (SL) heterostructures, forming as many as hundreds of individual layers, with some of the layers having sub-nanometer thicknesses. Therefore, the growth of these devices requires atomic layer precision in thickness control in order to achieve an overall strain-balanced system where defects are minimized, leading to superior crystalline quality and acceptable device performance. Molecular beam epitaxy is a crystal growth technique that is ideal for this endeavor, with growth of IC related structures spanning a range of III-V materials including InAs, GaSb, AlSb, and their related alloys on both InAs and GaSb substrates. A variety of MBE optimization and calibration efforts are presented, which tackle some of the most important SL and alloy structures in the ICL. Methodologies are developed to achieve nearly lattice-matched alloys with ideal composition parameters and minimal surface defects, characterized by differential interference contrast microscopy (DIC) and x-ray diffraction (XRD). Also, new growth techniques are developed and employed to achieve superior crystalline quality in SL systems, which led to nearly an order of magnitude reduction in the perpendicular mismatch between measurable SL structures and the substrate, and was implemented in GaSb-based ICLs to achieve the first ever growth of these structures on the GENxplor system in our group. While GaSb-based ICLs have demonstrated efficient room temperature (RT) operation in the 3-6 µm range, extending the operating wavelength of these ICLs presents several challenges including the reduced thermal conductivity of the optical cladding layers and the diminished electron-hole wavefunction overlap in the type-II QW, which arises due to the increased InAs QW width needed to support long wavelength emission. To alleviate the former concern, an advanced waveguide that was originally developed for InAs-based ICLs operating at 4.6 µm[7] was employed in InAs-based ICLs designed to emit beyond 10 µm. The advanced waveguide may enhance the device performance by reducing the free-carrier loss and improving the optical confinement in the cascade active region. Broad area (BA) devices made from InAs-based ICL wafers with this design feature showed operation in cw mode up to 10.9 µm at 80 K with output powers of up to 32 mW/facet, the largest output power among interband lasers at this wavelength, and up to 11.5 µm at 137 K in pulsed mode, the longest emission wavelength achieved for the standard W-QW active region ICL. To address the issue of the diminished electron-hole wavefunction overlap at longer wavelengths, InAs0.5P0.5 barriers are introduced, in addition to the standard AlSb barrier, in the W-QW active region, which have a lower valence band edge than the traditional AlSb barrier used. Based on the relevant perspective on band edge positions in type-II heterostructures[8], a barrier material with As or P containing compounds lowers the electronic state in the InAs QW. This allows the InAs well width to be reduced, or at least not increased as much, in devices designed to operate at longer wavelengths, which preserves a more substantial wavefunction overlap with the GaInSb hole well. The first implementation of this design yielded ICLs operating in pulsed mode up to 120 K beyond 13.2 µm, which is the longest wavelength ever achieved among III-V interband lasers and validated the prediction that such barrier layers could enhance the long wavelength emission.[8] ICLs with revised designs utilizing the advanced waveguide and the InAs0.5P0.5 barriers exhibited cw operation beyond 12.4 µm, which is the first demonstration of a BA ICL operating in cw mode at such a long wavelength, and up to 150 K, beyond 13 µm in pulsed mode. CW output powers beyond 12 mW/facet were measured, comparable with and even higher than previous ICLs without InAs0.5P0.5 barriers operating at much shorter wavelengths (<10 µm).[9]
The advanced waveguide was also investigated in GaSb-based ICLs tailored to emit near 3.3 and 3.4 µm at RT. The implementation of this feature resulted in cw operation of BA ICLs up to 260 K and pulsed operation up to 390 K, with RT threshold current densities as low as 151 A/cm2, akin to other GaSb-based ICLs using the conventional waveguide at similar wavelengths.[10] Furthermore, the characteristic temperature (To) of some of these ICLs was nearly 60 K at RT, which is the highest among RT ICLs with similar lasing wavelengths, indicating the potential for the advanced waveguide in GaSb-based ICLs designed to emit at shorter wavelengths
Políticas de lo gótico: sujeto marginal y cuerpos discapacitados en la narrativa gótica de Mariana Enríquez
Get PDFGothic literature represents what lies in the margins of society, with the forbidden and impossible. Following Jacques Rancière ideas on the politics of literature, this thesis explores the political implications of the Gothic narrative of Argentinian author Mariana Enríquez by analyzing the representation of marginalized subjects. In Mariana Enríquez's Gothic narrative, marginality and disability embody society's fears and anxieties by becoming monstruous. Nevertheless, this monstrosity is one created by the society that fears it. Enríquez's monsters are a product of a society where institutions themselves have become monstrous: the military dictatorship of the 70's and 80's ignores the law and disappears thousands of people, while the wealthy elites are allowed to utilize the bodies of marginalized groups for their own benefit. Disability becomes monstruous when it refuses to adapt to social ideas of normalcy. In "Nuestra parte de noche", the reinterpretation of disability by the religious sect of The Order ultimately serves their own interests: to control the bodies of their followers
Statistical Anomaly Discovery Through Visualization
Get PDFDeveloping a deep understanding of data is a crucial part of decision-making processes.
It often takes substantial time and effort to develop a solid understanding to make well-informed
decisions. Data analysts often perform statistical analyses through visualization
to develop such understanding. However, applicable insight can be difficult due to biases
and anomalies in data. An often overlooked phenomenon is mix effects, in which subgroups
of data exhibit patterns opposite to the data as a whole. This phenomenon is widespread
and often leads inexperienced analysts to draw contradictory conclusions. Discovering such
anomalies in data becomes challenging as data continue to grow in volume, dimensionality,
and cardinality. Effectively designed data visualizations empower data analysts to reveal
and understand patterns in data for studying such paradoxical anomalies.
This research explores several approaches for combining statistical analysis and visualization
to discover and examine anomalies in multidimensional data. It starts with an automatic
anomaly detection method based on correlation comparison and experiments to determine
the running time and complexity of the algorithm. Subsequently, the research investigates
the design, development, and implementation of a series of visualization techniques to fulfill
the needs of analysis through a variety of statistical methods. We create an interactive visual
analysis system, Wiggum, for revealing various forms of mix effects. A user study to evaluate
Wiggum strengthens understanding of the factors that contribute to the comprehension of
statistical concepts. Furthermore, a conceptual model, visual correspondence, is presented
to study how users can determine the identity of items between visual representations by
interpreting the relationships between their respective visual encodings. It is practical to
build visualizations with highly linked views informed by visual correspondence theory. We
present a hybrid tree visualization technique, PatternTree, which applies the visual
correspondence theory. PatternTree supports users to more readily discover statistical anomalies
and explore their relationships. Overall, this dissertation contributes a merging of new visualization
theory and designs for analysis of statistical anomalies, thereby leading the way to
the creation of effective visualizations for statistical analysis
Investigation of the Mechanical And Microstructural Properties in Coronary Arteries Following Decellularization
Get PDFThe heart is responsible for pumping blood throughout the body, and like all other
tissues, the heart muscle requires a supply of oxygen-rich blood to function properly. This blood
is supplied by the coronary arteries – the network of blood vessels on the surface of the heart.
There are two main coronary arteries: the left (main) coronary artery and the right coronary
artery. The left coronary artery divides into the left anterior descending artery (LADA) and the
left circumflex artery. The LADA is the largest of the coronary arteries, and it is the most
susceptible to disease. Coronary artery disease is characterized by plaque accumulation on the
inner arterial wall, which limits the blood flow to the heart muscle and can result in a heart
attack. In severe coronary artery disease, surgeons perform a procedure called coronary artery
bypass grafting (CABG), which bypasses the diseased portion of the artery by using a graft to
redirect blood from the aorta to the portion of the artery distal from the blockage. Usually, this
graft comes from another artery within the patient’s body; however, this is not always ideal due
to limited availability of viable vessels and high graft failure rates. When autologous grafts are
unable to be used, a vessel conduit is required, however, current coronary artery conduits are
suboptimal. An alternative approach to tissue-engineered vascular grafts is utilizing a donor
vessel’s native extracellular matrix (ECM) to serve as a scaffold. To minimize the risk of an
immune response from the patient, the donor vessel oftentimes needs to be decellularized to
remove all cellular components. While decellularization remains a promising approach, there is
not a standardized decellularization method for coronary arteries, and there is a lack of research
investigating how the microstructure behaves under pathologic loads following decellularization.
This thesis addresses this gap by proposing a novel protocol for the decellularization of porcine
coronary artery tissue that effectively removes cellular components, while retaining the native
tissue structure and function. This decellularization protocol consists of several treatments using
detergents, enzymes, and rinsing steps, and the removal of cells is confirmed using histology and
microscopic evaluation. To further determine the effect of this decellularization procedure on the
mechanical properties and collagen fiber architecture, biaxial mechanical testing and polarized
spatial frequency domain imaging (pSFDI) were performed before and after decellularization.
This investigation revealed minimal alteration to the mechanical and microstructural properties.
The findings of this thesis will be valuable to the refinement of coronary artery tissue grafts,
which may ultimately improve suboptimal outcomes in coronary bypass surgeries
Characterization of the protein-protein interactions of the type-II toxin-antitoxin system ParDE1 from Pseudomonas aeruginosa
No full textThe emergence of multidrug-resistant bacteria has led to an ever-growing antibiotic resistance crisis. To combat this growing crisis, new strategies for controlling bacterial cell growth must be developed. An underdeveloped target for new antimicrobial therapeutics are toxin-antitoxin (TA) systems. TA systems are widely dispersed genetic operons in prokaryotes which consist of a non-secreted protein (toxin) which targets essential metabolic enzymes causing cell death. The toxin’s cellular toxicity is neutralized by its cognate antitoxin (RNA or protein). In the case of type-II TA systems, the toxin protein is neutralized by directly binding to a protein antitoxin forming a toxin-antitoxin complex. The work presented within this dissertation aims to address several gaps in understanding how the protein-protein interactions of type-II TA systems are formed and maintained, with long term goals of targeting these protein-protein interactions to develop new means to control bacterial cell growth. This work focuses on the ParDE1 TA system from Pseudomonas aeruginosa, composed of the ParE toxin protein which targets DNA Gyrase
Performance and environmental impact assessment of agricultural waste-based sorbents for phosphorus recovery and reuse
Get PDFPhosphorus is an essential resource, yet global phosphorous reserves are limited, and increasing quantity of high-grade ore is being mined and turned into fertilizers to meet the increasing demand of food. However, since currently the phosphorus cycle is not closed loop, considerable amounts of excessive phosphorus are discharged from agricultural activities to environment causing eutrophication and wasting the resource. Hence, recovering and reusing phosphorus are key to building a sustainable phosphorus cycle. Materials derived from agricultural wastes such as biochar showed great potential of serving as a matrix for sorbents. Therefore, this research focused on sorbents prepared from agricultural wastes for recovering phosphorus from animal wastewater and reuse as fertilizer. Batch isotherm sorption phosphorus recovery studies and continuous flow column phosphorus release studies were conducted, as well as the life cycle assessment and cost analysis of producing the sorbents.
Biochars with magnesium amendments (referred as Mg-chars hereafter) from MgCl2 were tested in model animal wastewater at different pH conditions. Results showed precipitation as struvite was responsible for phosphorus recovery in model wastewater containing phosphate and ammonium, as confirmed through X-ray Diffraction (XRD). Additionally, since the solubility of struvite decreases with increasing pH, pH 8.0 and 9.0 were more beneficial for struvite formation. Furthermore, alkalinity in wastewater was found to compete with dissolved phosphorus on the sorbent.
Magnesium amendments such as using MgCl2 would often account for the major portion of the total cost producing the sorbents. To find cheaper solutions with similar phosphorus recovery performance, this research tested low-price magnesium sources including natural minerals and industrial by-products. Correspondingly, mineral magnesium hydroxide and bittern, a residue from sea salt evaporation, were identified as two alternatives for commercial MgCl2 salt. In concentrated animal wastewater at pH 8.0, Mg-char (Mg(OH)2) and Mg-char (bittern) both obtained phosphate recovery capacities over 220 mg P/g through struvite formation.
Additional to biochar, this research also tested materials synthesized from crop waste ashes. First, magnesium silicate minerals were prepared by extracting silicate from rice straw and wheat straw ash and then precipitated using magnesium salt. Even though magnesium silicate worked only slightly poorer than Mg-chars in terms of phosphorus recovery, the interference from dissolved silicate in concentrated wastewater on phosphate analysis was too high. Thus, magnesium silicate minerals were not tested further. Next, calcium silicate hydrate (CSH) was prepared using rice husk ash and calcium hydroxide. Unlike Mg-chars’ precipitation dominant phosphorus recovery mechanism, CSH fixed dissolved phosphate through a Langmuir type adsorption with maximum adsorption capacity of 55 mg P/g.
Next, post-phosphorus-exposure Mg-char (Mg(OH)2), Mg-char (bittern), and CSH were selected for phosphorus release test in continuous flow column studies considering the effects of pH and soil minerals goethite and kaolinite. Post-phosphorus-exposure sorbents, or spent sorbents, were collected from phosphorus recovery studies, then added to columns. Spent Mg-char (Mg(OH)2) and Mg-char (bittern) had phosphorus content of 182 and 198 mg P/g, respectively, and spent CSH had 46 mg P/g. Results showed that, first, both spent Mg-chars effectively released over 80 % of the recovered phosphorus within five pore volumes at pH 5.5, 7.0 and 8.5, but CSH needed significantly more pore volumes (time). Second, pH 5.5 and 7.0 yielded similar release characteristics while pH 8.5 was notably slower, which could be attributed to the lower solubility of struvite at higher pH. Third, soil minerals affect dissolved phosphate concentration greatly and goethite had more impact on phosphate availability than kaolinite. Further, at lower pH conditions, both minerals retained phosphate more than higher pH conditions, which was due to the fact that the further pH was lower than point of zero charge, the more affinity the mineral surface has for attracting phosphate ions.
Finally, this research evaluated the environmental impact of using Mg-char (Mg(OH)2), Mg-char (bittern), and CSH for phosphorus recovery and reuse comparing to commercial fertilizer monoammonium phosphate (MAP) through life cycle assessment (LCA), as well as cost analysis. While results suggested that both Mg-chars had lower environmental impact than MAP, CSH had the greatest environmental impact due to its high chemical inputs and biomass required. Further, Mg-char (bittern) had less impact than Mg-char (Mg(OH)2), illustrating the advantage of using bittern. Moreover, since Mg-chars achieved higher phosphorus release efficiency at lower pH soil, or when greater quantities of phosphorus release were needed for farmland with the same transportation distance, using Mg-chars for phosphorus management and fertilization could be even more advantageous than MAP. Finally, the two Mg-chars can be less expensive than MAP when the transportation cost was minimized or greater amount of phosphorus was needed.
Overall, this research provided knowledge on the use of several sorbents including magnesium amended biochars and silicate minerals that were derived from agricultural wastes for phosphorus recovery and reuse. These sorbents showed high potential as keys to a closed phosphorus cycle, and as substitutions to commercial fertilizers with less environmental impact and lower cost
Experimental investigation of polymer-based lost circulation materials for fluid loss treatment under high temperature using additive manufacturing
Get PDFLost circulation continues to be one of the most troublesome problems encountered during drilling.
The financial cost of lost circulation in geothermal drilling can rise to 15% of the total drilling
cost. A corrective approach to preventing lost circulation is using lost circulation materials (LCMs)
to plug the fractures in the wellbore, minimizing fluid loss and strengthening the wellbore. The
overall objective of this research is to test potential LCMs for sealing fractures under high-temperature conditions.
This research assessed the concept of recreating complex and drilling-induced fractures using 3D
printing. This study aims to generate fractures that look closer to the ones present downhole in
geothermal wells. Two LCMs, shape memory polymer (SMP) and crosslinked polymer, were
investigated for their potential to reduce fluid loss and seal complex fractures. Experimental
investigations, such as particle size distribution, rheology, gelation kinetics, alkalinity control, and
fracture sealing tests, were conducted to optimize the concentration of LCMs in drilling mud. The
experiments were conducted at temperatures between 93.3°C(200°F) to 150°C(302°F).
The results included the optimum concentration of SMP that can seal complex fracture zones.
Compared to walnuts, a conventional LCM, SMP significantly reduced mud loss. Additionally,
the importance of particle size distribution in the performance of granular LCMs is highlighted.
Rheology and gelation kinetics are essential for the settable crosslinked polymer in any successful
field application. This study's novelty is using a 3D-printed fracture disc for testing and optimizing
SMP and crosslinked polymer, which should reduce lost circulation in high-temperature
environments
Neural Signatures for Precision Rehabilitation in Stroke and Aging
Get PDFThe current growth of the population ages 65 and older is unprecedented. The number of these individuals is projected to nearly double by 2060 with the age group’s share of total population rising from 16 to 23 percent. With the growing number of older adults, there is also an increase in the demands of the public health system. Chronic noncommunicable diseases associated with age are on the rise, such as dementia, cardiovascular diseases including stroke, diabetes, and cancer. Therefore, the study of these conditions is critically important, not only because these diseases cause a significant loss of function, but also to reduce the burden on the caregiving and healthcare systems. The aim of this thesis is to explore neural signatures of stroke and aging related conditions for the development of precision interventions and treatments. The research on stroke includes early data of a pilot clinical trial on the use of a novel precision rehabilitation technique for improving upper extremity motor function post stroke, as well as research on cortical reorganization in the somatosensory area post stroke. The work on aging investigates sex-specific functional connectivity biomarkers in both the prodromal stage of Alzheimer’s Disease (AD), i.e., mild cognitive impairment, and AD. Beyond this thesis, the relationship between stroke and AD will be explored as our future work