In New York City conflict over street vending has evolved over the years, reflecting the political, economic, and social context of particular eras. This dissertation is focused primarily on the current era of vending regulation in New York and, more broadly, is concerned with the ways in which urban subjects are managed and urban space administered under neoliberalism. In New York, rather than being regulated in a straightforward manner that is guided by formal laws, the practice of street vending is managed informally on the part of store owners, building managers, police officers, even vendors themselves. The key mechanism through which this informal management occurs is legal ambiguity and uncertainty created by complex and convoluted vending laws, which leave vendors open to harassment and intimidation, particularly in high-value, central areas of the city under the control of Business Improvement Districts (BIDs). As vendors learn through experience the blocks or streets where they will receive the most harassment, they eventually police themselves, gravitating to parts of the city where property interests have less resources or influence to maintain effective control over vending. This produces a landscape of street vending where the spatial distribution of vendors is shaped less by actual laws, and is more of a reflection of the power, influence and resolve of individual property owners and property organizations such as BIDs. Through the case of street vending management, this study adds to our knowledge of spatial management in U.S. cities by showing the ways in which legal uncertainty and ambiguity can play a critical role in structuring space. For vendors, New York is not a city of clearly defined legal partitions or walls, but one of dispersed, shifting, and variegated regulations.

The dispersed and variegated nature of vending management also opens up opportunities for challenges and contestation. Vendors, despite mostly lacking citizenship and formal voting rights, nevertheless use a variety of tactics and strategies to contest their current situation. Vendors' political strategies focus heavily on demystifying vending regulations and holding the city and its enforcement agents accountable to the letter of the law. Where legal uncertainty and informal enforcement norms are some of the main tools used to control the spatiality of vending, clarifying murky regulations and demanding regularized enforcement, somewhat paradoxically, becomes a key strategy of resistance.

No legal tradition in history has developed an account of law and legal validity that compares in significance to that of legal positivism. Its most celebrated theorist in the 20th century, Hans Kelsen, conceptualizes legal validity as produced and reproduced within a self-referential system of law. Yet, by focusing on law’s self-referentiality, i.e., norms legitimating other norms, his theory fails to account for the complex interplay between positive and non-positive norms, and how this interplay is related to legal validity. More specifically, the positivist conception of law cannot account for how non-positive practices of legal adjudication produce and reproduce legal validity. To address this problem, I develop a “post-positivist” approach to legal validity grounded in non-positive norms of legal adjudication. I discuss three normative theories of legal adjudication that provide non-positive, practice-based accounts of legal validity. The three theories of adjudication I discuss are those of Ronald Dworkin, Jürgen Habermas, and Rainer Forst. In conclusion, a post-positivist approach to law means keeping positivism’s notion of self-referential legal validity, but introducing other normative inputs that compete with it without negating it in an on-going fashion.

Abstract

Gamma-ray Mapping

by

Ryan Thomas Pavlovsky

Doctor of Philosophy in Engineering - Nuclear Engineering

University of California, Berkeley

Kai Vetter, Chair

Advanced radiation detector sensors and detector systems have promoted the idea of

Gamma-Ray Mapping, the fusion of maps generated by contextual sensors with radiation

data. Gamma-Ray Mapping seeks to discover sources or distributions of radioactive isotopes

in the mapped measurement environment. As this suggests, there are two components to a

Gamma-Ray Mapping system: the map generation and Gamma-Ray imagers. This concept

has been motivated heavily by the availability of advanced gamma-ray detectors as well as

commercial sensors such as Global Positioning System (GPS), Light Imaging, Detection and

Ranging (LIDAR), Inertial Measurement Unit (IMU), etc., which can facilitate Simultaneous

Localization and Mapping (SLAM).

The role of Compton Imagers for Gamma-Ray Mapping has been explored for some

time [4][21][13]. These systems have good angular resolution, however they suffer from

imaging ambiguities in the Compton cones and require an ensemble of gamma-ray events to

reconstruct the source location. Electron Track Compton Imagers (ETCI) seek to break the

symmetry of Compton cones and eventually approach event-by-event gamma-ray momentum

computation. Additionally, these detectors provide the possibility of new imaging modalities

that rely only on electron tracks to recover the angular location and energy of a source [20].

ETCI has been shown to be conceptually possible [60] in high resolution 10.5 μm Super Novae

Acceleration Probe (SNAP) Charge Coupled Device (CCD) silicon detectors. However, there

are many practical issues with the implementation of CCD detectors as Compton imagers,

namely that time resolution in these devices is conservatively the Frame Read Time (FRT).

In typical SNAP devices the FRT can be ∼ 1 s/MPxl. The lack of time resolution limits

the use of CCD electron trackers in Compton imagers as well as in other radiation detector

system uses.

In order to circumvent the limit established by the FRT, CCD-strip was proposed. CCD-

strip devices conceptually provide time resolution on the order of the electron drift time in

n-type CCD detectors by application of strip segmentation to the CCD backside. Time

stamps would be correlated through the coarse strip spatial coding and the high resolution

electron tracks in the CCD pixel plane. Backside strips imply that double-sided, micrometer

alignment would be required for CCD-strip fabrication. Significant effort was required in the

coordination of the CCD fabrication facility Teledyne DALSA and strip detector fabrication

facility SINTEF. A small batch of CCD-strip devices were fabricated and tested in the

Lawrence Berkeley National Laboratory (LBNL) engineering test stand for screening pur-

poses. The bulk of this work’s contribution is in the construction and demonstration of the

newly fabricated devices in a custom test stand. The DALSA control wafers were the first

of this batch to produce electron tracks, and the device was characterized in our testbed.

The custom cryostat and measurement stand allowed us to reduce the leakage current in

CCD-Strip by a factor of 1000. The reduction removed voltage transients with equivalent

charge of about 3-5 MeV at the output of the preamplifiers. Ultimately the output baseline

had an Equivalent Noise Charge (ENC) of 400 keV-RMS per strip. The magnitude of the

ENC is large enough that strip operation is yet to be demonstrated.

Benchmarked simulations for the improvement of electron tracking and imaging algo-

rithms are also presented. From these simulations follows an investigation of the nuclear

scattering effect in electron trackers. Nuclear scattering is an important design consideration

for electron trackers as it scrambles the Compton kinematic information without producing

ionization, or signal, in electron trackers. From an examination of the nuclear scatter limit,

diamond was identified as a very interesting detector material for electron tracking. Dia-

mond is a material that minimizes nuclear scattering while maintaining photon efficiency.

This boosts the amount of ionization signal obtained from the initial portion of the electron

track. Electron-nuclear scattering is a large source of kinematic information loss in ETCI

systems.

Beyond complex detectors, augmentation of monolithic sensors with contextual sensors

to provide SLAM has been investigated for Gamma-Ray Mapping. Given the many types

of instruments which may be of interest, we constructed Localization and Mapping Plat-

form (LAMP), a data collection and demonstration platform for detectors and contextual

sensors. Here we used Google Cartographer as a SLAM solution. SLAM provides the 6

Degrees of Freedom (DOF) trajectory of a system, while simultaneously generating 3D mod-

els. These allow for ranging of gamma-ray emitters and the correction of detector responses

to provide better association of flux with physical objects. We demonstrated handheld and

Unmanned Aerial System (UAS) measurements as configurations for making these measure-

ments. LAMP, in handheld and flight configurations, provides a portable, robust indoor

and outdoor 3D SLAM solution for Gamma-Ray Mapping. LAMP was fitted with com-

mercial radiation detectors as a proof of concept. The radiation and scene data can be

fused by utilization of the SLAM output poses, trajectory and 3D model with simple back-

projection. The 3D backprojection scheme demonstrated incorporates simulated detector

angular responses for better resolution of hotspots than just backprojection alone. LAMP

has demonstrated that there is utility in coupling contextual sensors to augment simple com-

mercial detectors. Implementations that use commercial radiation detectors are important

to Gamma-Ray Mapping in that they represent the low end of the cost versus complexity for

mapping. We also demonstrate uses where GPS is either insufficient in function or accuracy.

LAMP will serve in the future as a demonstration platform for many kinds of detectors.

The development of ETCI and LAMP systems continues to expand the Gamma-Ray

Mapping application space. The developments in complex Gamma-Ray Imagers, coupled

with contextual platforms, consider the necessary components for Gamma-Ray Mapping.

This work has presents progress toward understanding the applicability and information

that ETCI systems provide, and we note that there is substantial work to be done toward

the goal of mapping with ETCI devices. The LAMP demonstration platform is crucial to

comparing technologies and understanding the complex problems that Gamma-Ray Mapping

poses. These parallel developments both share a part in enabling Gamma-Ray Mapping.

This work demonstrates the synthesis and characterization of several material systems that meet the required functional properties for direct integration in 3D lithium-ion microbatteries—conformal thin film solid-state electrolytes with adequate ionic conductivity and cathodes exhibiting high volumetric capacity, excellent rate capability, and cycle life. The atomic layer deposition (ALD) process optimization allowed for the control of the structural, chemical, and electrochemical properties of Li1+xMn2-xO4, LixAlySizO, as well as their interfacial properties that ultimately dictate electrochemical performance.

The synthesis of Li1+xMn2-xO4 combined a plasma enhanced ALD process for MnO2 and a thermal process for ALD LiOH. The PEALD MnO2 showed self-limiting growth, stable composition (within 5% relative composition), and well-controlled growth rate over a temperature range of 205-265�C. As synthesized and amorphous ALD Li1+xMn2-xO4 films were crystallized into the electrochemically active spinel phase. Tuning of the ALD cycle ratio led to controlled Li content in Li1+xMn2-xO4 (x = 0-0.33), exhibiting electrochemical activity in both the 3.0V and 4.0V region depending on the stoichiometry. The Li1+xMn2-xO4 thin films exhibited great rate capability and capacity retention—maintaining 66% of the areal capacity upon increasing the rate by a factor of a 100 as well as 97% capacity retention over 100 cycles at 35.9 �A cm-2 (~5C). The measured volumetric capacity was 52 �Ah cm-2 �m-1 at ~C/2 and 45 �Ah cm-2 �m-1 after 100 cycles at ~5C, offering the potential for superior areal energy densities.

Amorphous LixAlySizO thin films were synthesized and integrated on SiGe alloying anodes. Using in-situ transmission electron microscopy, the electrolyte layer was remained intact during the lithiation induced volume expansion of the nanowire for two different electrolyte thicknesses (8 and 20 nm). A novel hybrid solid-state electrolyte consisting of sequential deposition of ALD LixAlySizO and iCVD PV4D4 was synthesized to improve upon the mechanical properties of LixAlySizO for direct integration with high capacity anodes. Integration on Co3O4 thin films resulted in increased capacity-retention with continuous cycling with a discharge capacity 8.4% higher as compared to the uncoated Co3O4 anode after 100 cycles at ~2C.

The stoichiometry of ALD LixAlySizO was controlled to allow for crystallization in the β-eucryptite phase for improved ionic conductivities. The crystallized LiAlSiO4 exhibited a well-defined epitaxial relationship of β-LiAlSiO4 (12 ̅10) || Si (100) and β-LiAlSiO4 (101 ̅0) || Si(001). The ionic conductivity of the crystallized thin film was around two orders higher than the amorphous as-deposited films (10-7 vs. 10-9 S/cm) at room temperature. Due to the unique 1-D channel along the c-axis of β-LiAlSiO4, the epitaxial thin film has the potential to facilitate ionic transport if oriented with the c-axis normal to the electrode surface making it a promising electrolyte material for 3D lithium-ion Microbatteries, where a properly oriented film offers the opportunity to achieve higher ionic conductivities.

There has been a recurrent debate in generative phonology concerning the inclusion of hierarchical prosodic structure in phonological representations. On one side, there are those who argue that prosodic structure plays an indispensable role in the conditioning of phonological phenomena, especially stress, intonation, and segmental phonotactics. On the other side of the divide are researchers who suggest that all such phenomena yield to empirically adequate non-structural analyses, which are independently favored by criteria of theoretical parsimony.

This dissertation focuses on one aspect of the larger debate over prosodic organization: the existence of the metrical foot. In standard conceptions of phonological structure the foot is a prosodic constituent, falling between the syllable and the word, which mediates the assignment of word-level stress. The foot obviously has no role to play in non-structural theories of prosody. Such frameworks assume that stress assignment is not dependent on prosodic constituents, but is instead directly computed over segments or syllables on a metrical grid.

The evidence brought to bear on the choice of prosodic theory has, by-and-large, been drawn from the typology of attested stress patterns. Both structural and non-structural theories of stress appear capable of modelling roughly the same range of stress systems. Consequently, many of the arguments for or against foot structure have centered on the ability of each theory to express the typology of stress assignment in a compact, elegant, and predictive way. This dissertation expands the terms of the debate by examining foot-conditioned phonotactics, and to a lesser extent foot-conditioned morphology, as a window on the nature of prosodic constituency in natural language.

A major conclusion of this dissertation is that hierarchical prosodic structure must be admitted as part of phonological representations in order to capture the full range of prosodically-conditioned segmental phonotactics found in natural language. Three case studies form the heart of this claim. Specifically, I show that Huariapano, Uspanteko, and Irish all manifest foot-dependent phonotactics that cannot be insightfully analyzed without recourse to abstract metrical structure. Importantly, these arguments go beyond claims about relative theoretical elegance: non-structural analyses simply fail to account for the relevant phonological phenomena in an explanatory way.

In arguing for a foot-based theory of stress assignment, I also make the case for a fairly traditional conception of the metrical foot. First, I contend that stress is always assigned on the basis of foot structure, and only to foot heads, though feet may be unstressed or `covert' as well. Second, I argue that feet are always maximally binary, even in languages where stress assignment itself is ambiguous between binary and unbounded footing. Third, I propose that any given language makes use of at most one system or `tier' of metrical organization (the uniformity of footing hypothesis). In particular, I demonstrate that the rhythmic phonology of Huariapano can and should be modeled within a single, unified system of foot structure, despite previous claims to the contrary. Along the way, I identify a novel source of phonological prominence effects: the augmentation of foot-initial syllables.

The dissertation closes with an artificial grammar study exploring how language learners acquire foot-conditioned segmental phonotactics. Given the `hidden' character of abstract prosodic structure, foot-conditioned phonotactics pose an interesting learning problem. This is especially true given the recent rise of the view that all synchronic phonological knowledge is the result of inductive learning over phonetic regularities in the speech stream. The results of the artificial grammar study suggest that speakers of both English and Japanese were inclined to learn a stress-conditioned vowel phonotactic in terms of foot structure rather than stress per se. The experiment thus supports the claim that language learning is sensitive to a foot-based parsing bias that encourages the use of the foot as a general explanatory device in acquisition. These findings provide a possible explanation for why binary foot structure is found in languages lacking rhythmic, foot-based stress, and suggest that the foot may be a prosodic universal.

Introduction: Approximately two million people present to the emergency department (ED) with eye-related complaints each year in the United States. Differentiating pathologies that need urgent consultation from those that do not is imperative. For some physicians, ocular ultrasound has eclipsed the dilated fundoscopic exam as the standard posterior segment evaluation in the ED.

Case report: A 60-year-old female presented with sudden onset visual disturbance in her right eye. Point-of-care ultrasound showed a hyperechoic band in the posterior segment concerning for a retinal detachment. Ophthalmology was consulted and diagnosed the patient with a condition known as Valsalva retinopathy. The patient was discharged from the ED with expectant management.

Conclusion: This case highlights an important differential diagnosis that should be considered when ocular ultrasound demonstrates a hyperechoic band in the posterior segment. While previous literature has demonstrated that emergency physicians are able to accurately identify posterior segment pathology using ultrasound, there is limited information regarding their ability to differentiate between pathologies, some of which may not require urgent consultation. We highlight the important differentials that should be considered when identifying posterior segment pathology on point-of-care ultrasound and their appropriate dispositions.

Temporal lobe epilepsy (TLE) is a form of acquired epilepsy characterized by recurrent and unprovoked seizures. TLE often develops following a precipitating neurological insult, such as traumatic brain injury, stroke, infection, prolonged febrile seizures or status epilepticus. These insults can initiate a constellation of genetic, functional, network and systems level reorganization that transforms a normal non-epileptic brain into one capable of generating recurrent and unprovoked seizures. The period of time between neurological insults and the onset of epilepsy is known as the latent period and is believed to be the period of time during which underlying epileptogenic processes occur.

The dentate gyrus (DG) region of the hippocampus plays a key role in contextual learning and memory and strongly regulates the flow of neural activity from cortical regions into seizure-prone hippocampal regions through emergent properties of its neural microcircuit. In TLE, this filtering function is disrupted and can contribute to generation of seizures. Recent studies have described pathological high-frequency oscillations (pHFOs) in the DG and identified them as potential biomarkers of underlying proconvulsant network abnormalities. Moreover, pHFOs appear to be harbingers of TLE and are generated in the DG prior to the onset of an epileptic phenotype and therefore may reflect underlying network reorganization

during the epileptogenesis. Currently, little is known about the emergence of pHFOs after epilepsy-inducing neuronal insults or the pathological microcircuit that generates them. To address this we used a new mouse model of TLE to track the temporal and spectral evolution of pHFOs during epileptogenesis. Moreover, we investigated how disrupted integration of newly generated granule cells into the DG during epileptogenesis contributes to the disruption of DG microcircuit function.

We found that DG pHFOs are generated in bursts in vivo during epileptogenesis but that their burst properties do not evolve over time. In contrast, pHFO spectral dynamics appear to evolve during the latent period, suggesting that pHFO properties change according to the epileptogenic stage. In vitro electrophysiologcal and optogenetic experiments revealed that NGCs abnormally integrate into the DG microcircuit during epileptogenesis and that optogenetic activation of these neurons is sufficient to induce pHFOs in the DG.