Community by [DESIGN] by Community: Product & Process

In his seminal work De Architectura (The Ten Books on Architecture), the Roman architect Vitruvius proposed a definition that became a lasting benchmark for the elements of [DESIGN] -Firmness, Commodity, and Delight. While this three-part definition provided a common lens through which to view [DESIGN], it also created a divide between the trained \u27specialists\u27 who create [DESIGN] and the Community who experience and interact with it. For Vitruvius, [DESIGN] provided a physical demarcation of place and created a shared association that was collectively understood as a Community. As the idea of Community has become increasingly dissociated with place in the physical world, it has become more strongly identified as the collective experience shared by a group of people and the resulting values they hold. The relationship between the Product and Process of [DESIGN] is a critical component of the relationship between [DESIGN] and Community. Product and Process should not be considered as disparate entities but understood as mutually beneficial and influential components of both [DESIGN] and Community. When [DESIGN] and Community embrace a Process of mutualistic interaction it creates a Product that converges the intrinsic values and components of both. The traditional model of [DESIGN] engaging communities involves a top-down, Product centric approach identified and discussed as [Community by DESIGN]. At the other end of the spectrum, many Communities have self organized and worked from the bottom-up in a Process oriented approach categorized as [DESIGN by Community]. This thesis begins with a critical examination of each of these methodologies within the context of the Vitruvian Triad as a framework for understanding the existing divide between [DESIGN] and Community. It will then close with a critical examination of how the convergence of these concepts yields constructs that are both Product & Process based. For the purpose of this thesis, these critical points are demonstrated by examining a fabrication project executed by the author that embodies the assertion of the thesis. By actively seeking the convergence of [DESIGN] and Community, each is able to achieve a level of actualization beyond that which is possible in isolation. This convergence is understood as [Community by DESIGN by Community]

Effects of Antenna Beam Chromaticity on Redshifted 21~cm Power Spectrum and Implications for Hydrogen Epoch of Reionization Array

Unaccounted for systematics from foregrounds and instruments can severely limit the sensitivity of current experiments from detecting redshifted 21~cm signals from the Epoch of Reionization (EoR). Upcoming experiments are faced with a challenge to deliver more collecting area per antenna element without degrading the data with systematics. This paper and its companions show that dishes are viable for achieving this balance using the Hydrogen Epoch of Reionization Array (HERA) as an example. Here, we specifically identify spectral systematics associated with the antenna power pattern as a significant detriment to all EoR experiments which causes the already bright foreground power to leak well beyond ideal limits and contaminate the otherwise clean EoR signal modes. A primary source of this chromaticity is reflections in the antenna-feed assembly and between structures in neighboring antennas. Using precise foreground simulations taking wide-field effects into account, we provide a framework to set cosmologically-motivated design specifications on these reflections to prevent further EoR signal degradation. We show HERA will not be impeded by such spectral systematics and demonstrate that even in a conservative scenario that does not perform removal of foregrounds, HERA will detect EoR signal in line-of-sight $k$-modes, $k_\parallel \gtrsim 0.2\,h$~Mpc$^{-1}$, with high significance. All baselines in a 19-element HERA layout are capable of detecting EoR over a substantial observing window on the sky.Comment: 11 pages, 6 figures (10 total including subfigures), submitted to Ap

Cochlear Implant Training Model

Currently available training methods for cochlear implant surgeries such as cadavers and imaging systems are expensive and available for a limited number of training sessions. With the goal of decreasing risk factors associated with cochlear implant surgery, our team developed a cochlear implant training model prototype that is designed to provide a trial-and-error, tactile training method for developing force perception levels required to avoid causing damage to the cochlea. This model is designed to utilize a disposable material that ruptures when exposed to critical force levels. A material testing device was developed and utilized to test an assortment of easily accessible, thin materials that could be used by the training model. Further testing is still required before selecting the final material for the training model. An overview of potential material selection methods is given to improve future material testing results

Antigen Presentation in Central Nervous System Antitumor Immunity

Glioblastoma multiforme (GBM) patients face limited treatment options and poor outcomes. The median survival is less than two years, and there are no FDA approved immune therapies. Although GBM itself is an immune-suppressive, heterogeneous tumor, the lack of FDA approved immune therapies might be in part because the cancer immunity cycle is less well understood for GBM than for other tumor types. My studies focused on developing mouse models of malignant glioma that more faithfully recapitulate human GBM from an immunologic perspective, and on defining the role of the conventional dendritic cell 1 subset (cDC1) and lymphatic drainage in central nervous system (CNS) antitumor immunity. While genetically engineered mouse models of glioma have been described, they are for various reasons unsuitable to study the immune system’s reaction against the tumor, due to their use of outbred mice, immunologically immature mice, human oncogenes to drive transformation, or highly inflammatory initiation events. Furthermore, the most commonly deleted tumor suppressors in GBM are underrepresented in existing models. Thus, we engineered the tumor suppressor genes p16INK4a and p19ARF (INK4a/ARF; CDKN2A/B in humans) and phosphate and tensin homolog (PTEN) to be loxP-flanked on a pure C57BL/6 background. We used lentiviral transduction of Cre and the murine oncogene platelet derived growth factor beta (PDGFβ) to conditionally delete these tumor suppressors and transform target cells in brains of immunologically mature mice, which resulted in brain tumor formation. With the standard treatment, GBM invariably recurs, with 20%-30% of cases hypermutated. It is often the loss of mutS homolog 6 (MSH6), a mismatch repair protein, that confers resistance to temozolomide (standard-treatment) and leads to treatment-induced hypermutations. We developed the tools to model this phenomenon in a preclinically. We isolated astrocytes from the B6 INK4a/ARFfl/fl x PTENfl/fl mice and transformed them with the Cre/mPDGFβ lentivirus constructs. We used CRISPR to delete the mismatch repair protein MSH6 in these ex-vivo transformed astrocytes. We characterized their resistance to temozolomide and successfully induced hypermutation with long term temozolomide treatment and inhibition. Within the immunologically distinct location of the CNS the type of antigen presenting cell (APC) responsible for priming T cell responses against brain tumors remains undefined. In other non-CNS tumors, the conventional dendritic cell 1 (cDC1) subset cross-presents tumor-derived and cell-associated tumor antigen to generate antitumor CD8+ and CD4+ T cell responses. However, the homeostatic brain parenchyma is largely devoid of cDC1—their steady state location is restricted to the choroid plexus and the dura. Using orthotopic, syngeneic transplant models of murine glioblastoma, we investigated the roles of cDC1 and other antigen presenting cells in antitumor immunity of the CNS. We used the cDC1-deficient interferon regulatory factory 8-deficient (IRF8+32-/-) mice to determine that cDC1 are required to mediated αPD-L1 induced survival benefit as well as to generate neoantigen-specific CD8+ T cell responses against the brain tumors. Furthermore, using a fluorescent tracking system, we observed that dendritic cells (including the cDC1 subset) isolated from the tumor, the lymphatic vessel-containing dura, and the cervical lymph nodes harbored tumor-derived antigen. We extended these findings to humans. We identified several subsets of conventional dendritic cells, including the CD141+ cDC1 equivalent, in the immune cell infiltrate of a variety of human brain tumor types (including GBM), as well as in the tumor-adjacent dura. We determined tumor-infiltrating dendritic cells, including the CD141+ subset (equivalent to the mouse cDC1), contained the tumor-specific fluorescent metabolite of 5-aminolevulinic acid (5-ALA), protoporphyrin IX (PPIX), which is used for fluorescence guided resection of malignant glioma. The PPIX signal was absent in both tumor-infiltrating T cells and equivalent dendritic cell subsets isolated from intraoperatively harvested peripheral blood, which indicates that this phenomenon was specific to antigen presenting cells that had infiltrated the tumor. To our knowledge, this is the first observation in humans of antigen presenting cells ingesting tumor-derived material. Together, these data provide evidence that cDC1 play a significant role in CNS antitumor immunity in mice and humans. Collectively, these studies have yielded improved tools to study the immunity cycle in GBM and have shed light on some of the elements regarding the nature and mechanism of antigen presentation in CNS antitumor immunity

The Hydrogen Epoch of Reionization Array Dish II: Characterization of Spectral Structure with Electromagnetic Simulations and its science Implications

We use time-domain electromagnetic simulations to determine the spectral characteristics of the Hydrogen Epoch of Reionization Arrays (HERA) antenna. These simulations are part of a multi-faceted campaign to determine the effectiveness of the dish's design for obtaining a detection of redshifted 21 cm emission from the epoch of reionization. Our simulations show the existence of reflections between HERA's suspended feed and its parabolic dish reflector that fall below -40 dB at 150 ns and, for reasonable impedance matches, have a negligible impact on HERA's ability to constrain EoR parameters. It follows that despite the reflections they introduce, dishes are effective for increasing the sensitivity of EoR experiments at relatively low cost. We find that electromagnetic resonances in the HERA feed's cylindrical skirt, which is intended to reduce cross coupling and beam ellipticity, introduces significant power at large delays ($-40$ dB at 200 ns) which can lead to some loss of measurable Fourier modes and a modest reduction in sensitivity. Even in the presence of this structure, we find that the spectral response of the antenna is sufficiently smooth for delay filtering to contain foreground emission at line-of-sight wave numbers below $k_\parallel \lesssim 0.2$ $h$Mpc$^{-1}$, in the region where the current PAPER experiment operates. Incorporating these results into a Fisher Matrix analysis, we find that the spectral structure observed in our simulations has only a small effect on the tight constraints HERA can achieve on parameters associated with the astrophysics of reionization.Comment: Accepted to ApJ, 18 pages, 17 Figures. Replacement matches accepted manuscrip

Agile, Post-quantum Secure Cryptography in Avionics

To introduce a post-quantum-secure encryption scheme specifically for use in flight-computers, we used avionics’ module-isolation methods to wrap a recent encryption standard (HPKE – Hybrid Public Key Encryption) within a software partition. This solution proposes an upgrade to HPKE, using quantum-resistant ciphers (Kyber/ML-KEM and Dilithium/ML-DSA) redundantly alongside well-established ciphers, to achieve post-quantum security. Because cryptographic technology can suddenly become obsolete as attacks become more sophisticated, crypto-agility -– the ability to swiftly replace ciphers – represents the key challenge to deployment of software like ours. Partitioning is a crucial method for establishing such agility, as it enables the replacement of compromised software without affecting software on other partitions, greatly simplifying the certification process necessary in an avionics environment. Our performance measurements constitute initial evidence that both the memory and performance characteristics of this approach are suitable for deployment in flight-computers currently in use. Prior to optimisation, performance measurements show a modest memory requirement of under 400 KB of RAM, but employ a more substantial stack usage of just under 200 KB. Our most advanced redundant post-quantum cipher is five times slower than its non-redundant, pre-quantum counterpart

What Next-Generation 21 cm Power Spectrum Measurements Can Teach Us About the Epoch of Reionization

A number of experiments are currently working towards a measurement of the 21 cm signal from the Epoch of Reionization. Whether or not these experiments deliver a detection of cosmological emission, their limited sensitivity will prevent them from providing detailed information about the astrophysics of reionization. In this work, we consider what types of measurements will be enabled by a next-generation of larger 21 cm EoR telescopes. To calculate the type of constraints that will be possible with such arrays, we use simple models for the instrument, foreground emission, and the reionization history. We focus primarily on an instrument modeled after the $\sim 0.1~\rm{km}^2$ collecting area Hydrogen Epoch of Reionization Array (HERA) concept design, and parameterize the uncertainties with regard to foreground emission by considering different limits to the recently described "wedge" footprint in k-space. Uncertainties in the reionization history are accounted for using a series of simulations which vary the ionizing efficiency and minimum virial temperature of the galaxies responsible for reionization, as well as the mean free path of ionizing photons through the IGM. Given various combinations of models, we consider the significance of the possible power spectrum detections, the ability to trace the power spectrum evolution versus redshift, the detectability of salient power spectrum features, and the achievable level of quantitative constraints on astrophysical parameters. Ultimately, we find that $0.1~\rm{km}^2$ of collecting area is enough to ensure a very high significance ($\gtrsim30\sigma$) detection of the reionization power spectrum in even the most pessimistic scenarios. This sensitivity should allow for meaningful constraints on the reionization history and astrophysical parameters, especially if foreground subtraction techniques can be improved and successfully implemented.Comment: 27 pages, 18 figures, updated SKA numbers in appendi

The Precision Array for Probing the Epoch of Reionization: 8 Station Results

We are developing the Precision Array for Probing the Epoch of Reionization (PAPER) to detect 21cm emission from the early Universe, when the first stars and galaxies were forming. We describe the overall experiment strategy and architecture and summarize two PAPER deployments: a 4-antenna array in the low-RFI environment of Western Australia and an 8-antenna array at our prototyping site in Green Bank, WV. From these activities we report on system performance, including primary beam model verification, dependence of system gain on ambient temperature, measurements of receiver and overall system temperatures, and characterization of the RFI environment at each deployment site. We present an all-sky map synthesized between 139 MHz and 174 MHz using data from both arrays that reaches down to 80 mJy (4.9 K, for a beam size of 2.15e-5 steradians at 154 MHz), with a 10 mJy (620 mK) thermal noise level that indicates what would be achievable with better foreground subtraction. We calculate angular power spectra ($C_\ell$) in a cold patch and determine them to be dominated by point sources, but with contributions from galactic synchrotron emission at lower radio frequencies and angular wavemodes. Although the cosmic variance of foregrounds dominates errors in these power spectra, we measure a thermal noise level of 310 mK at $\ell=100$ for a 1.46-MHz band centered at 164.5 MHz. This sensitivity level is approximately three orders of magnitude in temperature above the level of the fluctuations in 21cm emission associated with reionization.Comment: 13 pages, 14 figures, submitted to AJ. Revision 2 corrects a scaling error in the x axis of Fig. 12 that lowers the calculated power spectrum temperatur