Alexis Johnson - Academia.edu (original) (raw)

Papers by Alexis Johnson

Frontiers in Marine Science

The Loop Current Eddy (LCE) separation cycle energizes deep circulation in the eastern Gulf of Me... more The Loop Current Eddy (LCE) separation cycle energizes deep circulation in the eastern Gulf of Mexico, transferring energy from the surface intensified Loop Current (LC) to the typically quiescent lower layers. To document the generation and radiation of deep energy during this cycle, an array of 24 current and pressure recording inverted echo sounders (CPIES) is deployed in the region 89°W to 86°W, 25°N to 27.5°N with the intent to capture circulation near bathymetric features thought to be important for current-topographic interactions: Campeche Bank, Mississippi Fan, and West Florida Shelf. During the nearly two-year deployment, June 2019 to May 2021, three LCE separation events are observed, during which energy injected into the deep Gulf organizes into two distinct frequency bands (1/100 – 1/20 days–1 and 1/20 – 1/10 days–1). High-frequency variability dominates the array’s northwest corner in the vicinity of the Mississippi Fan. Wave properties are consistent with topographic ...

2022 IEEE/OES Autonomous Underwater Vehicles Symposium (AUV)

Annales de l'Institut Fourier

Let k be a number field. We give an explicit bound, depending only on [k : Q] and the discriminan... more Let k be a number field. We give an explicit bound, depending only on [k : Q] and the discriminant of the Néron-Severi lattice, on the size of the Brauer group of a K3 surface X/k that is geometrically isomorphic to the Kummer surface attached to a product of isogenous CM elliptic curves. As an application, we show that the Brauer-Manin set for such a variety is effectively computable. Conditional on GRH, we can also make the explicit bound depend only on [k : Q] and remove the condition that the elliptic curves be isogenous. In addition, we show how to obtain a bound, depending only on [k : Q], on the number of C-isomorphism classes of singular K3 surfaces defined over k, thus proving an effective version of the strong Shafarevich conjecture for singular K3 surfaces. Résumé.-Soit k un corps de nombres. On donne une borne explicite, dépendant uniquement de [k : Q] et du discriminant du réseau de Néron-Severi, pour la taille du groupe de Brauer de toute surface K3 X/k qui est géométriquement isomorphe à la surface Kummer attachée à un produit de courbes elliptiques de type CM isogènes. Comme application, on montre que l'ensemble de Brauer-Manin pour une telle variété est effectivement calculable. Sous l'hypothèse de Riemann généralisée, on peut de plus faire dépendre la borne explicite uniquement de [k : Q] et supprimer la contrainte d'isogénéité des courbes elliptiques. En outre, on montre comment obtenir une borne, dépendant uniquement de [k : Q], pour le nombre de classes d'isomorphismes sur C de surfaces K3 singulières définies sur k, prouvant ainsi une version effective de la conjecture forte de Shafarevich pour les surfaces K3 singulières.

The oceanic biological carbon pump encompasses a variety of mechanisms by which CO2, fixed into o... more The oceanic biological carbon pump encompasses a variety of mechanisms by which CO2, fixed into organic form by phytoplankton, is transported from the sunlit surface layers to the interior ocean. Here, we investigate submesoscale and mixed layer subduction, the physical arm of the biological pump, estimated to represent approximately 20% of global organic carbon (POC) export. Seven biogeochemical Argo (BGC) profiling floats were analyzed for evidence of physical subduction of POC in the North Atlantic Ocean. While we do not yet have enough measurements to reveal basin wide spatial trends, a notable pattern is found in the seasonality, suggesting that while subduction events are more likely to occur during winter, the bio-optical indicators - namely a deep local maxima in POC and O2 - are more common in the spring and summer. We show that these deep features are potentially long-lived, having been subducted in late winter or spring and persisting throughout the warm season. To demons...

Compensation is a crucial tool utilized by companies to help attract, retain, and motivate employ... more Compensation is a crucial tool utilized by companies to help attract, retain, and motivate employees. However, previous research has overlooked the ways in which compensation might add value to important employee outcomes such as engagement and organizational tenure. Therefore, this present study aimed to close this gap by examining the relationship between pay level and engagement, as well as pay level and organizational tenure. It was hypothesized that higher pay levels would increase the engagement dimensions of dedication, vigor, and absorption in an employee, and that Additionally I'd like to acknowledge the unconditional, if sometimes with a little kick, support and love from my mom and brother. Finally, I would like to acknowledge and dedicate this thesis to my Dad, who never wavered in his belief of my ability and potential, who always taught me to push myself mentally (and from whom I inherited my love of statistics), and who would've been so proud to see that I finally accomplished another endeavor I set out to do on my own. You are missed every day, Dad, and this one's for you. vi

Infection Control & Hospital Epidemiology, 2022

Objective:To assess characteristics and perceptions associated with vaccine hesitancy among healt... more Objective:To assess characteristics and perceptions associated with vaccine hesitancy among healthcare workers to increase coronavirus disease 2019 (COVID-19) vaccine uptake in this population.Design:Cross-sectional quantitative survey.Setting:A not-for-profit healthcare system in southwestern Virginia.Participants:A convenience sample of 2,720 employees of a not-for-profit healthcare system.Methods:Between March 15 and 29, 2021, we conducted an Internet-based survey. Our questionnaire assessed sociodemographic and work-related characteristics, vaccine experience and intentions, agreement with vaccine-related perceptions, the most important reasons for getting or not getting vaccinated, and trusted sources of information about COVID-19. We used χ2 analyses to assess the relationship between vaccine hesitancy and both HCW characteristics and vaccine-related perceptions.Results:Overall, 18% of respondents were classified as vaccine hesitant. Characteristics significantly associated wi...

Unrestricted Through the analysis of the early works of contemporary, Los Angeles-based Conceptua... more Unrestricted Through the analysis of the early works of contemporary, Los Angeles-based Conceptual artist Allen Ruppersberg (born 1944), this thesis will examine and contextualize the artist's engagement with the ideas of location, the conditions of the city that affected his process and the artist's interest in the rejection of the preciousness of the art object. The artwork produced between 1968 and 1972 provides a discrete body of work focused within and utilizing images indicative of the site of Los Angeles, reflective of the region's psychogeography and the reality of the individual's requisite mobility in a city framed by freeways. Ruppersberg employed numerous strategies—particularly that of shifting reality only minutely to translate it into art—to investigate this confluence of ideas. The influence of Los Angeles on Ruppersberg's early work is a crucial and under-examined point in L.A. art history and will be the subject of this manuscript.

ue to more than 50 years of rapid population growth and increased agricultural activity, nitrate ... more ue to more than 50 years of rapid population growth and increased agricultural activity, nitrate (NO3) concentrations in Florida’s groundwater, springs, and rivers have increased dramatically. Shifts from macrophytic to algal cover in many of these systems are thought to result from this change in nutrient loading; however the linkages between hydrology, microbial communities, and nutrient processing are not well understood. In-stream nitrate concentrations are typically determined by autotrophic uptake as well as denitrification in biofilms and sediments of the hyporheic zone (HZ). While the hyporheic zone has been identified as a biogeochemical processing “hot spot,” its contribution to overall nitrate removal is debated (Chapman et al., 1995; Heffernan & Cohen, 2010). Numerous studies have shown that respiration in the HZ accounts for 40-90% of total stream ecosystem respiration and Hinkle et al (2001) showed that on the 1-2 km reach scale, 1/3 of hyporheic zones showed almost co...

This dissertation is dedicated first to my devoted, loving, and incredible husband and family, wi... more This dissertation is dedicated first to my devoted, loving, and incredible husband and family, without them I could not be where I am today. They have shaped and molded me into the woman I am. First, I dedicate this dissertation to my beloved mother, Pamela. My mother passed away from Stage IV breast cancer in 2011 at the age of 60. She battled five years courageously and taught me to always keep fighting any adversity that should come my way. Without her battle, I would not be doing what I am doing. I research cancer caregivers so that I may help others cope with the many demands, sorrows, and challenges that follow a cancer diagnosis. To my Mother: My Mother was more than just a cancer diagnosis. My Mother was a fighter, lover, and inspiration to all who met her. My Mother was beautiful inside and out. My Mother used to dance, sing, and shout. My Mother was my best friend. My Mother loved us so deeply, even until the very end. My Mother had a beautiful, young soul. My Mother made friends with all, whether young or old. My Mother taught me to be the very best I can be. My Mother is a part of me. For anyone who never got an opportunity to meet the amazing person that she was. They will get to see a piece of her from my brother and I. We are her living legacy. We are the people she was most proud of, and will always be. I miss my mother every day. The pain will never really go away. To honor her and remember her, I have dedicated my life to helping other people faced with this same fate. I am proud to say I am researching, and working with anyone I can so that they may not feel as alone as I did. Cancer is a horrible disease, full of pain and suffering. However, we can and should continue to raise awareness and talk about the realities of the disease. I hope to open the conversation, help

Journal of Geophysical Research: Oceans, 2021

The oceanic biological carbon pump encompasses a variety of mechanisms by which CO 2 , fixed into... more The oceanic biological carbon pump encompasses a variety of mechanisms by which CO 2 , fixed into organic form by phytoplankton, is transported from the sunlit surface layers to the interior ocean. Here, we investigate submesoscale and mixed layer subduction, the physical arm of the biological pump, estimated to represent approximately 20% of global organic carbon (POC) export. Seven biogeochemical Argo (BGC) profiling floats were analyzed for evidence of physical subduction of POC in the North Atlantic Ocean. While we do not yet have enough measurements to reveal basin wide spatial trends, a notable pattern is found in the seasonality, suggesting that while subduction events are more likely to occur during winter, the bio-optical indicators-namely a deep local maxima in POC and O 2-are more common in the spring and summer. We show that these deep features are potentially long-lived, having been subducted in late winter or spring and persisting throughout the warm season. To demonstrate, we focus on a set of notably strong POC anomalies, observed in ten consecutive BGC Argo profiles on the northeastern edge of the subtropical gyre. Analysis of the physical, bio-optical and biogeochemical profiles, complemented by remote sensing and modeling, provides insight into the history and subsequent fate of that water mass. This work highlights the potential of bio-optically and biogeochemically-equipped floats for process-style assessments of the biological carbon pump and the value added by increasing the number of BGC floats throughout the oceans.

Journal of Parasitology, 2021

Foodborne pathogens continue to pose a public health risk and can cause serious illness and outbr... more Foodborne pathogens continue to pose a public health risk and can cause serious illness and outbreaks of disease in consumers. The consumption of raw or undercooked infected meat, such as pork containing infectious stages of Toxoplasma gondii, may be a major route of transmission to humans. Given the occasional presence of T. gondii in pork meat and the frequent use of pork for products not intended to be cooked, such as dry-cured ham, a potential risk exists for T. gondii transmission to consumers of these products. The purpose of this study was to determine the seroprevalence of T. gondii in U.S. market hogs and sows at slaughter. A total of 20,209 sera samples collected from 22 U.S. slaughterhouses, including 15 of the top 25 largest slaughter plants in the United States, were tested for T. gondii antibodies using a commercial ELISA assay. Seroprevalence in this study was 0.74%, with a herd prevalence of 10.86%. We compared seroprevalence of T. gondii in market hogs vs. sows from a separate but geographically similar set of slaughterhouse locations, with serum samples screened using the T. gondii modified agglutination test. This set of market hogs demonstrated 0% seroprevalence for T. gondii, while sows from geographically similar but separate slaughter facilities demonstrated a seroprevalence of 1.03%. Overall, both analyses show low seroprevalence of T. gondii in U.S market hogs and sows, respectively, and a marked drop in prevalence in market hogs and sows compared to previous studies.

Journal of the American Heart Association, 2020

Background Mental health after spontaneous coronary artery dissection ( SCAD ), a cause of myocar... more Background Mental health after spontaneous coronary artery dissection ( SCAD ), a cause of myocardial infarction in young women, remains largely unexplored. We assessed the prevalence and severity of psychiatric symptoms after SCAD . Methods and Results Individuals with confirmed SCAD who consented to the Mayo Clinic “Virtual” Multicenter SCAD Registry were sent the Posttraumatic Stress Disorder Diagnostic Scale for Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition , Patient Health Questionnaire‐9, Generalized Anxiety Disorder‐7, Anxiety Sensitivity Index, Connor‐Davidson Resilience Scale, 36‐Item Short‐Form Health Survey, and an SCAD ‐specific questionnaire. Among 782 patients contacted, 512 surveys were returned. Most respondents were women (97.5%), with median age at time of SCAD and survey completion of 47 and 52 years, respectively. Eighty‐two percent had at least one trauma, with mild or more posttraumatic stress disorder symptoms in 28%. Symptoms of anxiety...

The Journal of the Acoustical Society of America, 2019

A detailed understanding of ecological soundscapes provides a window into ecosystem state that mi... more A detailed understanding of ecological soundscapes provides a window into ecosystem state that might otherwise go undetected. Rather than consider acoustic emissions of a particular species, a top down ecosystem acoustics point of view gives potentially valuable insights to reef ecosystem function. Simultaneous passive acoustic and video data were collected from coral reefs off the Kona Coast of Hawaii in January 2019 during a soundscape experiment. Frequent interactions between fish species as well as collective behaviors are identified and tracked by applying computer vision to video data. Comparison relating video data to acoustic data allows assessment of the same behaviors as simultaneously reflected in directional passive acoustic data. Collective consideration of acoustics and video offers insight into acoustic signatures of particular soniferous communities and behaviors amongst and between reef species. Machine learning applications match patterns between fish trajectories in videos and the sound field as received by a directional antenna. The relative level of biological activity and presence or absence of particular behaviors provides key data in the effort to understand coral reef ecosystem state.

The Journal of the Acoustical Society of America, 2019

Biological sources contribute significantly to coral reef ambient noise environments, yet the eco... more Biological sources contribute significantly to coral reef ambient noise environments, yet the ecosystem-level mechanisms of temporal and spatial variation in the reef soundscape are not well understood. In this study, subtle shifts in reef ambient noise are examined using unsupervised machine learning on hydrophone array data. Unsupervised learning does not require data labels, but uses nonlinear inference to find explanatory features within the data. A hydrophone array was used to generate spatially filtered time series inputs for machine learning. Video cameras were collocated and time-synced with the hydrophone array to provide nominal ground-truth. We discuss the tradeoff parameters of the unsupervised learning methods. Changes in the dominant data features during the experiment are compared to the video recordings and researcher observations.Biological sources contribute significantly to coral reef ambient noise environments, yet the ecosystem-level mechanisms of temporal and spatial variation in the reef soundscape are not well understood. In this study, subtle shifts in reef ambient noise are examined using unsupervised machine learning on hydrophone array data. Unsupervised learning does not require data labels, but uses nonlinear inference to find explanatory features within the data. A hydrophone array was used to generate spatially filtered time series inputs for machine learning. Video cameras were collocated and time-synced with the hydrophone array to provide nominal ground-truth. We discuss the tradeoff parameters of the unsupervised learning methods. Changes in the dominant data features during the experiment are compared to the video recordings and researcher observations.

The Journal of the Acoustical Society of America, 2019

Health Communication, 2019

With cancer increasing in prevalence and high priorities placed on concurrent oncological and pal... more With cancer increasing in prevalence and high priorities placed on concurrent oncological and palliative care to help meet the familial, spiritual, and individual needs of stakeholders in cancer, research is needed that assesses the factors that facilitate coping across stakeholders in cancer care. We were interested in synthesizing our understanding of communication and relationships among patients, caregivers, and providers based on the reasoning that illness is relational, but often conceptualized and researched from the individual perspectives of various stakeholders. The current study examined the experiences of relational and communication opportunities and challenges during cancer for current and former family caregivers, cancer survivors, and palliative and oncology health care practitioners. The thematic analysis of 30 semi-structured interviews revealed an overarching theme on the benefits of orienting toward cancer as communal, which was, in turn, facilitated or impeded by four additional themes/sets of behaviors: support, presence, perspective-taking, and reframing hope. Results of a crosscase data matrix analysis reveal that stakeholders in different roles experience qualitative differences in their experience of cancer as communal, isolated, or ambivalent. Implications for education, palliative care, and interventions are discussed. The psychosocial needs of patients, families, and providers have become a central priority in the delivery of quality cancer care (Institute of Medicine [IOM], 2013), particularly given projected increases in new cancer cases by 45% over the next 15 years (American Society of Clinical Oncology [ASCO], 2014). Research programs that concurrently optimize oncological and palliative care are of high priority (Smith et al., 2012) for cancer patients and their family members and health care providersall of whom face challenges in the context of cancer care (Wittenberg-Lyles, Goldsmith, Ragan, & Sanchez-Reilly, 2010). Communication is particularly difficult in the context of cancer because practitioners often postpone disclosing illness severity (e.g., Beckstrand, Moore, Callister, & Bond, 2009), and conversations among family members about mortality can increase emotional discomfort and vulnerability (Donovan-Kicken & Caughlin, 2010). These issues can create divides among patients, caregivers, and practitioners who struggle to understand each other's needs and perspectives. One way to bridge divides and help individuals cope with their challenges is to, first, understand the uniqueness and intersections of experience across those involved in cancer care. Previous research rarely examines all vantage points of the cancer experience in the same study. This is problematic because we have little sense of the ways in which patients, providers, and family caregivers experience and perceive the same communication and relational issues as shared or divisive. We were interested in synthesizing our understanding of communication and relationships among patients, caregivers, and providers given that illness is relational, though often conceptualized and researched from individual stakeholder perspectives (Wolf, 2015). Interventions to date have focused on psychoeducational programs that train these stakeholders separately (Bakitas et al.,

Frontiers in Marine Science

The Loop Current Eddy (LCE) separation cycle energizes deep circulation in the eastern Gulf of Me... more The Loop Current Eddy (LCE) separation cycle energizes deep circulation in the eastern Gulf of Mexico, transferring energy from the surface intensified Loop Current (LC) to the typically quiescent lower layers. To document the generation and radiation of deep energy during this cycle, an array of 24 current and pressure recording inverted echo sounders (CPIES) is deployed in the region 89°W to 86°W, 25°N to 27.5°N with the intent to capture circulation near bathymetric features thought to be important for current-topographic interactions: Campeche Bank, Mississippi Fan, and West Florida Shelf. During the nearly two-year deployment, June 2019 to May 2021, three LCE separation events are observed, during which energy injected into the deep Gulf organizes into two distinct frequency bands (1/100 – 1/20 days–1 and 1/20 – 1/10 days–1). High-frequency variability dominates the array’s northwest corner in the vicinity of the Mississippi Fan. Wave properties are consistent with topographic ...

2022 IEEE/OES Autonomous Underwater Vehicles Symposium (AUV)

Annales de l'Institut Fourier

Let k be a number field. We give an explicit bound, depending only on [k : Q] and the discriminan... more Let k be a number field. We give an explicit bound, depending only on [k : Q] and the discriminant of the Néron-Severi lattice, on the size of the Brauer group of a K3 surface X/k that is geometrically isomorphic to the Kummer surface attached to a product of isogenous CM elliptic curves. As an application, we show that the Brauer-Manin set for such a variety is effectively computable. Conditional on GRH, we can also make the explicit bound depend only on [k : Q] and remove the condition that the elliptic curves be isogenous. In addition, we show how to obtain a bound, depending only on [k : Q], on the number of C-isomorphism classes of singular K3 surfaces defined over k, thus proving an effective version of the strong Shafarevich conjecture for singular K3 surfaces. Résumé.-Soit k un corps de nombres. On donne une borne explicite, dépendant uniquement de [k : Q] et du discriminant du réseau de Néron-Severi, pour la taille du groupe de Brauer de toute surface K3 X/k qui est géométriquement isomorphe à la surface Kummer attachée à un produit de courbes elliptiques de type CM isogènes. Comme application, on montre que l'ensemble de Brauer-Manin pour une telle variété est effectivement calculable. Sous l'hypothèse de Riemann généralisée, on peut de plus faire dépendre la borne explicite uniquement de [k : Q] et supprimer la contrainte d'isogénéité des courbes elliptiques. En outre, on montre comment obtenir une borne, dépendant uniquement de [k : Q], pour le nombre de classes d'isomorphismes sur C de surfaces K3 singulières définies sur k, prouvant ainsi une version effective de la conjecture forte de Shafarevich pour les surfaces K3 singulières.

The oceanic biological carbon pump encompasses a variety of mechanisms by which CO2, fixed into o... more The oceanic biological carbon pump encompasses a variety of mechanisms by which CO2, fixed into organic form by phytoplankton, is transported from the sunlit surface layers to the interior ocean. Here, we investigate submesoscale and mixed layer subduction, the physical arm of the biological pump, estimated to represent approximately 20% of global organic carbon (POC) export. Seven biogeochemical Argo (BGC) profiling floats were analyzed for evidence of physical subduction of POC in the North Atlantic Ocean. While we do not yet have enough measurements to reveal basin wide spatial trends, a notable pattern is found in the seasonality, suggesting that while subduction events are more likely to occur during winter, the bio-optical indicators - namely a deep local maxima in POC and O2 - are more common in the spring and summer. We show that these deep features are potentially long-lived, having been subducted in late winter or spring and persisting throughout the warm season. To demons...

Compensation is a crucial tool utilized by companies to help attract, retain, and motivate employ... more Compensation is a crucial tool utilized by companies to help attract, retain, and motivate employees. However, previous research has overlooked the ways in which compensation might add value to important employee outcomes such as engagement and organizational tenure. Therefore, this present study aimed to close this gap by examining the relationship between pay level and engagement, as well as pay level and organizational tenure. It was hypothesized that higher pay levels would increase the engagement dimensions of dedication, vigor, and absorption in an employee, and that Additionally I'd like to acknowledge the unconditional, if sometimes with a little kick, support and love from my mom and brother. Finally, I would like to acknowledge and dedicate this thesis to my Dad, who never wavered in his belief of my ability and potential, who always taught me to push myself mentally (and from whom I inherited my love of statistics), and who would've been so proud to see that I finally accomplished another endeavor I set out to do on my own. You are missed every day, Dad, and this one's for you. vi

Infection Control & Hospital Epidemiology, 2022

Objective:To assess characteristics and perceptions associated with vaccine hesitancy among healt... more Objective:To assess characteristics and perceptions associated with vaccine hesitancy among healthcare workers to increase coronavirus disease 2019 (COVID-19) vaccine uptake in this population.Design:Cross-sectional quantitative survey.Setting:A not-for-profit healthcare system in southwestern Virginia.Participants:A convenience sample of 2,720 employees of a not-for-profit healthcare system.Methods:Between March 15 and 29, 2021, we conducted an Internet-based survey. Our questionnaire assessed sociodemographic and work-related characteristics, vaccine experience and intentions, agreement with vaccine-related perceptions, the most important reasons for getting or not getting vaccinated, and trusted sources of information about COVID-19. We used χ2 analyses to assess the relationship between vaccine hesitancy and both HCW characteristics and vaccine-related perceptions.Results:Overall, 18% of respondents were classified as vaccine hesitant. Characteristics significantly associated wi...

Unrestricted Through the analysis of the early works of contemporary, Los Angeles-based Conceptua... more Unrestricted Through the analysis of the early works of contemporary, Los Angeles-based Conceptual artist Allen Ruppersberg (born 1944), this thesis will examine and contextualize the artist's engagement with the ideas of location, the conditions of the city that affected his process and the artist's interest in the rejection of the preciousness of the art object. The artwork produced between 1968 and 1972 provides a discrete body of work focused within and utilizing images indicative of the site of Los Angeles, reflective of the region's psychogeography and the reality of the individual's requisite mobility in a city framed by freeways. Ruppersberg employed numerous strategies—particularly that of shifting reality only minutely to translate it into art—to investigate this confluence of ideas. The influence of Los Angeles on Ruppersberg's early work is a crucial and under-examined point in L.A. art history and will be the subject of this manuscript.

ue to more than 50 years of rapid population growth and increased agricultural activity, nitrate ... more ue to more than 50 years of rapid population growth and increased agricultural activity, nitrate (NO3) concentrations in Florida’s groundwater, springs, and rivers have increased dramatically. Shifts from macrophytic to algal cover in many of these systems are thought to result from this change in nutrient loading; however the linkages between hydrology, microbial communities, and nutrient processing are not well understood. In-stream nitrate concentrations are typically determined by autotrophic uptake as well as denitrification in biofilms and sediments of the hyporheic zone (HZ). While the hyporheic zone has been identified as a biogeochemical processing “hot spot,” its contribution to overall nitrate removal is debated (Chapman et al., 1995; Heffernan & Cohen, 2010). Numerous studies have shown that respiration in the HZ accounts for 40-90% of total stream ecosystem respiration and Hinkle et al (2001) showed that on the 1-2 km reach scale, 1/3 of hyporheic zones showed almost co...

This dissertation is dedicated first to my devoted, loving, and incredible husband and family, wi... more This dissertation is dedicated first to my devoted, loving, and incredible husband and family, without them I could not be where I am today. They have shaped and molded me into the woman I am. First, I dedicate this dissertation to my beloved mother, Pamela. My mother passed away from Stage IV breast cancer in 2011 at the age of 60. She battled five years courageously and taught me to always keep fighting any adversity that should come my way. Without her battle, I would not be doing what I am doing. I research cancer caregivers so that I may help others cope with the many demands, sorrows, and challenges that follow a cancer diagnosis. To my Mother: My Mother was more than just a cancer diagnosis. My Mother was a fighter, lover, and inspiration to all who met her. My Mother was beautiful inside and out. My Mother used to dance, sing, and shout. My Mother was my best friend. My Mother loved us so deeply, even until the very end. My Mother had a beautiful, young soul. My Mother made friends with all, whether young or old. My Mother taught me to be the very best I can be. My Mother is a part of me. For anyone who never got an opportunity to meet the amazing person that she was. They will get to see a piece of her from my brother and I. We are her living legacy. We are the people she was most proud of, and will always be. I miss my mother every day. The pain will never really go away. To honor her and remember her, I have dedicated my life to helping other people faced with this same fate. I am proud to say I am researching, and working with anyone I can so that they may not feel as alone as I did. Cancer is a horrible disease, full of pain and suffering. However, we can and should continue to raise awareness and talk about the realities of the disease. I hope to open the conversation, help

Journal of Geophysical Research: Oceans, 2021

The oceanic biological carbon pump encompasses a variety of mechanisms by which CO 2 , fixed into... more The oceanic biological carbon pump encompasses a variety of mechanisms by which CO 2 , fixed into organic form by phytoplankton, is transported from the sunlit surface layers to the interior ocean. Here, we investigate submesoscale and mixed layer subduction, the physical arm of the biological pump, estimated to represent approximately 20% of global organic carbon (POC) export. Seven biogeochemical Argo (BGC) profiling floats were analyzed for evidence of physical subduction of POC in the North Atlantic Ocean. While we do not yet have enough measurements to reveal basin wide spatial trends, a notable pattern is found in the seasonality, suggesting that while subduction events are more likely to occur during winter, the bio-optical indicators-namely a deep local maxima in POC and O 2-are more common in the spring and summer. We show that these deep features are potentially long-lived, having been subducted in late winter or spring and persisting throughout the warm season. To demonstrate, we focus on a set of notably strong POC anomalies, observed in ten consecutive BGC Argo profiles on the northeastern edge of the subtropical gyre. Analysis of the physical, bio-optical and biogeochemical profiles, complemented by remote sensing and modeling, provides insight into the history and subsequent fate of that water mass. This work highlights the potential of bio-optically and biogeochemically-equipped floats for process-style assessments of the biological carbon pump and the value added by increasing the number of BGC floats throughout the oceans.

Journal of Parasitology, 2021

Foodborne pathogens continue to pose a public health risk and can cause serious illness and outbr... more Foodborne pathogens continue to pose a public health risk and can cause serious illness and outbreaks of disease in consumers. The consumption of raw or undercooked infected meat, such as pork containing infectious stages of Toxoplasma gondii, may be a major route of transmission to humans. Given the occasional presence of T. gondii in pork meat and the frequent use of pork for products not intended to be cooked, such as dry-cured ham, a potential risk exists for T. gondii transmission to consumers of these products. The purpose of this study was to determine the seroprevalence of T. gondii in U.S. market hogs and sows at slaughter. A total of 20,209 sera samples collected from 22 U.S. slaughterhouses, including 15 of the top 25 largest slaughter plants in the United States, were tested for T. gondii antibodies using a commercial ELISA assay. Seroprevalence in this study was 0.74%, with a herd prevalence of 10.86%. We compared seroprevalence of T. gondii in market hogs vs. sows from a separate but geographically similar set of slaughterhouse locations, with serum samples screened using the T. gondii modified agglutination test. This set of market hogs demonstrated 0% seroprevalence for T. gondii, while sows from geographically similar but separate slaughter facilities demonstrated a seroprevalence of 1.03%. Overall, both analyses show low seroprevalence of T. gondii in U.S market hogs and sows, respectively, and a marked drop in prevalence in market hogs and sows compared to previous studies.

Journal of the American Heart Association, 2020

Background Mental health after spontaneous coronary artery dissection ( SCAD ), a cause of myocar... more Background Mental health after spontaneous coronary artery dissection ( SCAD ), a cause of myocardial infarction in young women, remains largely unexplored. We assessed the prevalence and severity of psychiatric symptoms after SCAD . Methods and Results Individuals with confirmed SCAD who consented to the Mayo Clinic “Virtual” Multicenter SCAD Registry were sent the Posttraumatic Stress Disorder Diagnostic Scale for Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition , Patient Health Questionnaire‐9, Generalized Anxiety Disorder‐7, Anxiety Sensitivity Index, Connor‐Davidson Resilience Scale, 36‐Item Short‐Form Health Survey, and an SCAD ‐specific questionnaire. Among 782 patients contacted, 512 surveys were returned. Most respondents were women (97.5%), with median age at time of SCAD and survey completion of 47 and 52 years, respectively. Eighty‐two percent had at least one trauma, with mild or more posttraumatic stress disorder symptoms in 28%. Symptoms of anxiety...

The Journal of the Acoustical Society of America, 2019

A detailed understanding of ecological soundscapes provides a window into ecosystem state that mi... more A detailed understanding of ecological soundscapes provides a window into ecosystem state that might otherwise go undetected. Rather than consider acoustic emissions of a particular species, a top down ecosystem acoustics point of view gives potentially valuable insights to reef ecosystem function. Simultaneous passive acoustic and video data were collected from coral reefs off the Kona Coast of Hawaii in January 2019 during a soundscape experiment. Frequent interactions between fish species as well as collective behaviors are identified and tracked by applying computer vision to video data. Comparison relating video data to acoustic data allows assessment of the same behaviors as simultaneously reflected in directional passive acoustic data. Collective consideration of acoustics and video offers insight into acoustic signatures of particular soniferous communities and behaviors amongst and between reef species. Machine learning applications match patterns between fish trajectories in videos and the sound field as received by a directional antenna. The relative level of biological activity and presence or absence of particular behaviors provides key data in the effort to understand coral reef ecosystem state.

The Journal of the Acoustical Society of America, 2019

Biological sources contribute significantly to coral reef ambient noise environments, yet the eco... more Biological sources contribute significantly to coral reef ambient noise environments, yet the ecosystem-level mechanisms of temporal and spatial variation in the reef soundscape are not well understood. In this study, subtle shifts in reef ambient noise are examined using unsupervised machine learning on hydrophone array data. Unsupervised learning does not require data labels, but uses nonlinear inference to find explanatory features within the data. A hydrophone array was used to generate spatially filtered time series inputs for machine learning. Video cameras were collocated and time-synced with the hydrophone array to provide nominal ground-truth. We discuss the tradeoff parameters of the unsupervised learning methods. Changes in the dominant data features during the experiment are compared to the video recordings and researcher observations.Biological sources contribute significantly to coral reef ambient noise environments, yet the ecosystem-level mechanisms of temporal and spatial variation in the reef soundscape are not well understood. In this study, subtle shifts in reef ambient noise are examined using unsupervised machine learning on hydrophone array data. Unsupervised learning does not require data labels, but uses nonlinear inference to find explanatory features within the data. A hydrophone array was used to generate spatially filtered time series inputs for machine learning. Video cameras were collocated and time-synced with the hydrophone array to provide nominal ground-truth. We discuss the tradeoff parameters of the unsupervised learning methods. Changes in the dominant data features during the experiment are compared to the video recordings and researcher observations.

The Journal of the Acoustical Society of America, 2019

Health Communication, 2019

With cancer increasing in prevalence and high priorities placed on concurrent oncological and pal... more With cancer increasing in prevalence and high priorities placed on concurrent oncological and palliative care to help meet the familial, spiritual, and individual needs of stakeholders in cancer, research is needed that assesses the factors that facilitate coping across stakeholders in cancer care. We were interested in synthesizing our understanding of communication and relationships among patients, caregivers, and providers based on the reasoning that illness is relational, but often conceptualized and researched from the individual perspectives of various stakeholders. The current study examined the experiences of relational and communication opportunities and challenges during cancer for current and former family caregivers, cancer survivors, and palliative and oncology health care practitioners. The thematic analysis of 30 semi-structured interviews revealed an overarching theme on the benefits of orienting toward cancer as communal, which was, in turn, facilitated or impeded by four additional themes/sets of behaviors: support, presence, perspective-taking, and reframing hope. Results of a crosscase data matrix analysis reveal that stakeholders in different roles experience qualitative differences in their experience of cancer as communal, isolated, or ambivalent. Implications for education, palliative care, and interventions are discussed. The psychosocial needs of patients, families, and providers have become a central priority in the delivery of quality cancer care (Institute of Medicine [IOM], 2013), particularly given projected increases in new cancer cases by 45% over the next 15 years (American Society of Clinical Oncology [ASCO], 2014). Research programs that concurrently optimize oncological and palliative care are of high priority (Smith et al., 2012) for cancer patients and their family members and health care providersall of whom face challenges in the context of cancer care (Wittenberg-Lyles, Goldsmith, Ragan, & Sanchez-Reilly, 2010). Communication is particularly difficult in the context of cancer because practitioners often postpone disclosing illness severity (e.g., Beckstrand, Moore, Callister, & Bond, 2009), and conversations among family members about mortality can increase emotional discomfort and vulnerability (Donovan-Kicken & Caughlin, 2010). These issues can create divides among patients, caregivers, and practitioners who struggle to understand each other's needs and perspectives. One way to bridge divides and help individuals cope with their challenges is to, first, understand the uniqueness and intersections of experience across those involved in cancer care. Previous research rarely examines all vantage points of the cancer experience in the same study. This is problematic because we have little sense of the ways in which patients, providers, and family caregivers experience and perceive the same communication and relational issues as shared or divisive. We were interested in synthesizing our understanding of communication and relationships among patients, caregivers, and providers given that illness is relational, though often conceptualized and researched from individual stakeholder perspectives (Wolf, 2015). Interventions to date have focused on psychoeducational programs that train these stakeholders separately (Bakitas et al.,