Emerging technologies in the healthcare industry encompass revolutionary devices or drugs that have the potential to change how healthcare will be practiced in the future. While there are several emerging healthcare technologies in the pipeline, a few key innovations are slated to be implemented clinically sooner based on their mass appeal and potential for healthcare breakthroughs. This thesis will focus on specific topics in the emerging technological fields of nanotechnology for photothermal cancer therapy, 3D printing for irreversible electroporation applications, and imageable biomaterials. While these general areas are receiving significant attention, we highlight the potential opportunities and limitations presented by our select efforts in these fields. First, in the realm of nanomedicine, we discuss the optimization and characterization of sodium thiosulfate facilitated gold nanoparticle synthesis. While many nanoparticles have been examined as agents for photothermal cancer therapy, we closely examine the structure and composition of these specific nanomaterials and discuss key findings that not only impact their future clinical use, but elucidate the importance of characterization prior to preclinical testing. Next, we examine the potential use of 3D printing to generate unprecedented multimodal medical devices for local pancreatic cancer therapy. This additive manufacturing technique offers exquisite design detail control, facilitating tools that would otherwise be difficult to fabricate by any other means. Lastly, in the field of imageable biomaterials, we demonstrate the development of composite catheters that can be visualized with near infrared imaging. This new biomaterial allows visualization with near infrared imaging, offering potentially new medical device opportunities that alleviate the use of ionizing radiation. This collective work emphasizes the need to thoroughly optimize and characterize emerging technologies prior to preclinical testing in order to facilitate rapid translation. / Master of Science

A lack of complex analysis for a thermally buoyant jet in a stratified crossflow has motivated the studies presented. A computational approach using the incompressible Navier--Stokes equations (NSE) under the Boussinesq approximation is utilized. Temperature and salinity scalar transport equations are utilized in conjunction with a linear equation of state (EOS) to obtain the density field and thus the buoyancy forcing. Comparing simulation data to experimental data of a point heat source in a stratified environment provides general agreement between the aforementioned computational model and the physics studied. From the literature surveyed, no unified agreement was presented on the selection of turbulence models for the jet--in--crossflow (JICF) problem. For this reason, a comparison is presented for a standard Reynolds--Averaged Navier--Stokes (RANS) and a hybrid Reynolds--Averaged Navier--Stokes/large eddy simulation (HRLES) turbulence model. The mathematical differences are outlined as well as the implications each model has on solving a buoyant jet in stratified crossflow. The RANS model provides a general over prediction of all flow quantities when comparing to the HRLES models. Studies involving the removal of the thermal component inside the jet as well as varying the environmental stratification strength have largely determined that these affects do not alter the near-field in any significant way, at least for a high Reynolds number JICF. The velocity ratio of the jet being the ratio of the jet velocity to the free--stream flow velocity. Deviating from a velocity ratio of one has provided information on the variability of the forcing on the plate the jet exits from, as well as in the integrated energy quantities far downstream of the jet's exit. The departures presented here show that any deviation from the unity value provides an increase in the overall forces seen by the plate. It was also found that the change in the integrated potential and turbulent kinetic energies is proportional to the deviation from a unity velocity ratio. / Master of Science / A lack of complex analysis for a heated jet in a non-uniform crossflow has motivated the studies presented. A computational approach for the fluid dynamics governing equations under specific assumptions is implemented. Additional equations are solved for temperature and salinity in conjunction with a linear equation of state to obtain the density field. Comparing simulations to experimental data of a point heat source in a non-uniform, fluid tank provides general agreement between the aforementioned computational model and the physics studied. Studying the literature yields no unified agreement on the selection of turbulence treatment for the jet-in-crossflow problem. For this reason, a comparison is presented for two various techniques with differing complexity. The mathematical differences as well as the implications each model are outlined, specifically pertaining to a heated jet in a non-uniform crossflow. The simpler model provides a general over prediction when compared to the more complex model. Studies involving the removal of the heat from inside the jet as well as varying the environmental forcing have largely determined that these affects do not alter the flow field near the jet's origin point in any significant way. Changing the jet's velocity has provided information on the variability of the forcing on the plate the jet exits from, as well as in the energy released into the environment far downstream of the jet's exit. The ratios presented show that any deviation from a notional value provides an increase in the overall forces seen by the plate. It was also found that the change in the released energies is proportional to the deviation from the notional jet velocity.

Microbes in nature live collaboratively in adherent communities, known as biofilms. Biofilms can be contextually beneficial or detrimental. In medical implants, biofilms cause infections leading to additional healthcare costs of billions of dollars. Studies have found that micro/nanoscale surface topography can significantly alter (i.e., promote or hinder) the process of biofilm formation. The formation of biofilm starts with planktonic microbes attach to the surface. To further understand the biophysical underpinning of this process, the effect of aligned nanoscale surface structures on microbial adhesion was studied. To this end, aligned nanofiber coating with controlled fiber diameter and edge-to-edge spacing were manufactured using the Spinneret-based Tunable Engineered Parameters (STEP) techniques. The effect of surface topography on bacterial near-surface motility was studied. The experimental results showed that the bacterial attachment and near-surface motion can be greatly impacted by surface topography. Furthermore, the finding was applied to ureteral stents. The results showed that the aligned nanofiber can significantly reduce the biofilm formation process on ureteral stents. / Master of Science / Many microbes in nature live in adherent communities called biofilm. Biofilms contain individual microbes inside polymeric matrix which protect them from environmental stressors such as antibiotics. Biofilms are a significant contributor to the infection of implantable medical devices, which leads to additional healthcare costs of billions of dollars annually in the U.S. alone. Studies have found that sub-micron scale surface topography can significantly promote or hinder biofilm formation; however, the exact mechanism remains poorly understood. To further understand this process, the effect of aligned nanoscale surface structures on microbial adhesion was studied. The formation of microbial biofilm starts with swimming bacteria sensing the liquid-solid interface and attaching to the surface. Microbes are more likely to settle on a surface if a surface is favorable to attach. However, the decision-making process has not been fully understood. Our experimental results showed that the bacterial attachment and near-surface motion can be greatly influenced by surface topography. Furthermore, the finding was applied to ureteral stents, which is a type of medical implants used to maintain the flow of urine in the urinary tract. Ureteral stents serve great for medical purposes, but as foreign bodies, they also lead to urinary tract infection. The results showed that some types of aligned fiber coating increased microbial attachment density, while other types of aligned fiber coating reduced the bacterial surface coverage by up to 80%, which provides directions for future studies.

Yes / In this study, we investigated whether reading influences contrast adaptation differently in young adult emmetropic and myopic participants at the spatial frequencies created by text rows and character strokes. Pre-adaptation contrast sensitivity was measured for test gratings with spatial frequencies of 1cdeg-1 and 4cdeg-1, presented horizontally and vertically. Participants then adapted to reading text corresponding to the horizontal “row frequency” of text (1cdeg-1), and vertical “stroke frequency” of the characters (4cdeg-1) for 180s. Following this, post-adaptation contrast sensitivity was measured. Twenty young adults (10 myopes, 10 emmetropes) optimally corrected for the viewing distance participated. There was a significant reduction in logCS post-text adaptation (relative to pre-adaptation logCS) at the row frequency (1cdeg-1 horizontal) but not at the stroke frequency (4cdeg-1 vertical). logCS changes due to adaptation at 1cdeg-1 horizontal were significant in both emmetropes and myopes. Comparing the two refractive groups, myopic participants showed significantly greater adaptation compared to emmetropic participants. Reading text on a screen induces contrast adaptation in young adult observers. Myopic participants were found to exhibit greater contrast adaptation than emmetropes at the spatial frequency corresponding to the text row frequency. No contrast adaptation was observed at the text stroke frequency in either participant group. The greater contrast adaptation experienced by myopes after reading warrants further investigation to better understand the relationship between near work and myopia development.

Yes / In this paper we consider the making, daily use and deposition of ornaments in the Halaf period. We seek to move beyond rigid ‘craft production’ interpretive frameworks intersecting symbolism, complexity and social inequality. Instead, we seek different ways of knowing prehistoric ornaments, through their materiality, assemblage and visuality as evidence of ambiguous mutable person-object relationships and experiences. Making and decoration of/with ornaments offers insights into social concepts of embodiment, personhood, identity and belonging, and should be interpreted as having ambiguous, multiple uses and meanings. Using six case studies of ornament types from excavated assemblages, we critically examine existing methods of small finds’ presentation and suggest more dynamic ways of artefact analysis, interpretation and publication. We present this interpretative model as a methodology applicable broadly to small find studies in all archaeological contexts. In our analysis we re-orient towards considering assemblages of dynamic communities of makers, users and identities embedded in these objects’ life histories.

Thesis advisor: Michael J. Naughton / For many centuries, physicists and engineers have explored the creation, manipulation and detection of light. Only within the past century, however, have fabrication techniques advanced to the point where individual photons can be generated, manipulated, and measured. These advances have brought us to the point we are at today, where photonic devices are set to revolutionize the fields of computing, sensing and quantum information, to name a few. Despite the promise of these devices, scientists are still working to fully understand the light-matter interactions that govern their behavior. In this thesis, we uniquely characterize the behavior of certain photonic devices in an effort to understand the underlying physical principles that define them. Of particular interest to us is imaging via near-field scanning optical microscopy (NSOM) of photonic integrated circuit (PIC) elements with high quality factors (Q), such as microring resonators and photonic crystal cavities (PhCs). While these elements are becoming ubiquitous in emerging PIC designs, they have remained difficult to accurately image due to their high sensitivity to small perturbations (i.e. the NSOM probe). We solve this problem by controllably modulating the NSOM tip-sample distance and reducing the size of the probe. Finite element model computer simulations demonstrate that both of these adjustments decrease the tip sample interaction. We then apply this knowledge to generate first of their kind 50 nm resolution NSOM images of high Q resonant PIC devices. Importantly, aside from being accurate, the proposed NSOM technique is also facile and non-destructive. In addition to local field exploration of PIC elements, we explore non-classical optical transmission through sub-wavelength apertures in metallic films. We demonstrate that these interesting features arise from photonic wave interference. / Thesis (PhD) — Boston College, 2024. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Physics.

The Anthropocene epoch in which we are currently living, also known as the Holocene, has brought about unprecedented losses in planet Earth’s biodiversity. Numerous extirpations of floral and faunal species have been influenced by human encroachment and more specifically, the exploitation of such species and the respective habitats in which they reside. It is this notion that has propelled many scientists to take up intellectual arms in an effort to protect these invaluable resources. The purpose of this research was to develop technologies to measure and evaluate various variables that influence animal physiology, specifically in amphibians who represent the most threatened class of all animal taxa. Species-specific knowledge including life history and an understanding of evolutionary traits are often needed to effectively guide the management decisions surrounding any given animal population. Specific objectives of this project were to develop non-invasive methods, such as hormone monitoring, machine learning-aided ultrasonography, and near-infrared spectroscopy (NIRS), to assess vital physiological traits, such as biological sex, reproductive status, and chytrid fungus pathogen detection in threatened amphibian species. The novel technologies developed and applied in amphibians here may provide insights for addressing conservation related questions in other animal as well as plant species. Additionally, automation of physiological monitoring techniques through the use of machine learning methods reduces barrier to entry and enables these technologies to be operated by a larger practitioner base. This research also serves to advance methods surrounding chemometric analyses as it pertains to the discipline of wildlife spectroscopy, where large multivariate datasets require data manipulation strategies to produce robust prediction models for the physiological trait of interest for qualitative or quantitative assessment. To that end, a multi-model framework is provided for optimizing predictive outcomes to address questions relating to wildlife management and conservation initiatives.

Yes / Near-peer teaching is becoming increasingly popular as a learning methodology. We report the development of a novel near-peer biological sciences revision course and its acceptability and impact on student confidence and exam performance. A cross-sectional analysis of tutee-completed evaluation forms before and after each session was performed, providing demographic details, quality scores, and self-rating of confidence in the topic taught on a 0 to 100 mm visual analogue scale (VAS). The confidence data was examined using analysis of means. Exam performance was examined by analysis of variance and canonical correlation analysis. Thirty-eight sessions were delivered to an average of 69.9 (±27.1) years 1 and 2 medical students per session generating 2656 adequately completed forms. There was a mean VAS gain of 19.1 (5.3 to 27.3) in self-reported confidence. Looking at relationship between attendance and exam scores, only two topics showed significant association between number of sessions attended and exam performance, fewer than hypothesised. The present study demonstrates that near-peer teaching for biological sciences is feasible and is associated with improved self-reported confidence in the sessions taught. The outcome data, showing significant effect for only a small number of items, demonstrates the difficulty of outcome related research.

No

Unwanted and distressing visual imagery is a persistent and emotionally taxing symptom characteristic of several mental illnesses, including depression, schizophrenia, and posttraumatic stress disorder. Intrusive imagery symptoms have been linked to maladaptive memory formation, abnormal visual cortical activity during viewing, gaze pattern deficits, and trait characteristics of mental imagery. Emotional valence of visual stimuli has been shown to alter perceptual processes that influence the direction of attention to visual information, which may result in enhanced attention to suboptimal and generalizable visual properties. This study tested the hypothesis that aberrant gaze patterns to central and peripheral image regions influence the formation of decontextualized visual details which may facilitate involuntary and emotionally negative mental imagery experiences following a stressful or traumatic event. Gaze patterns and hemodynamic response from occipital cortical locations were recorded while healthy participants (N = 39) viewed and imagined scenes with negative or neutral emotional valence. Self-report behavioral assessments of baseline vividness of visual imagery and various cognitive factors were combined with these physiological measures to investigate the potential relationship between visual perception and mental recreation of negative scenes. Results revealed significant effects of task and valence conditions on specific fixation measures and hemodynamic response patterns in ventral visual areas, which interacted with cognitive factors such as imagery vividness and familiarity. Findings further suggest that behaviors observed during mental imagery reveal processes related to representational formation over and above perceptual performance and may be applied to the study of disorders such as PTSD. / Ph. D. / Intrusive imagery describes the visual components of flashbacks that are common to mental disorders such as posttraumatic stress disorder (PTSD), obsessive-compulsive disorder, and schizophrenia. Several explanations for this symptom have been suggested, including incomplete memories, changes in visual brain structures and function, inappropriate viewing patterns, and an individual’s ability to imagine visual scenes in detail. The emotional tone of a scene has also been shown to affect viewing patterns, which may lead to attention being narrowly directed toward specific visual details while ignoring surrounding information. This study tested whether inappropriate viewing patterns to central and outer image regions in negative images influence narrow focus to emotional details, thereby allowing flashback-type imagery to occur following a traumatic or stressful event. Viewing patterns and blood flow in brain regions were measured while participants (<i>N</i> = 39) viewed and imagined scenes with negative or neutral emotional tone. Self-reported detail of voluntary mental imagery and other cognitive factors such as content familiarity and pleasantness were used to investigate a relationship between viewing and imagery of emotionally negative scenes. Results showed that certain cognitive factors as well as the type of visual task significantly affected particular eye movements and patterns of blood flow in visual regions of the brain. These measures interacted with cognitive factors such as imagery detail and content familiarity. Findings further suggest that behaviors observed during mental imagery reveal cognitive processes over and above those during viewing and may be useful in the study of disorders such as PTSD.