Matching Items (258)
Description
Like individual organisms, complex social groups are able to maintain predictable trajectories of growth, from initial colony foundation to mature reproductively capable units. They do so while simultaneously responding flexibly to variation in nutrient availability and intake. Leafcutter ant colonies function as tri-trophic systems, in which the ants harvest vegetation to grow a fungus that, in turn, serves as food for the colony. Fungal growth rates and colony worker production are interdependent, regulated by nutritional and behavioral feedbacks. Fungal growth and quality are directly affected by worker foraging decisions, while worker production is, in turn, dependent on the amount and condition of the fungus. In this dissertation, I first characterized the growth relationship between the workers and the fungus of the desert leafcutter ant Acromyrmex versicolor during early stages of colony development, from colony foundation by groups of queens through the beginnings of exponential growth. I found that this relationship undergoes a period of slow growth and instability when workers first emerge, and then becomes allometrically positive. I then evaluated how mass and element ratios of resources collected by the ants are translated into fungus and worker population growth, and refuse, finding that colony digestive efficiency is comparable to digestive efficiencies of other herbivorous insects and ruminants. To test how colonies behaviorally respond to perturbations of the fungus garden, I quantified activity levels and task performance of workers in colonies with either supplemented or diminished fungus gardens, and found that colonies adjusted activity and task allocation in response to the fungus garden size. Finally, to identify possible forms of nutrient limitation, I measured how colony performance was affected by changes in the relative amounts of carbohydrates, protein, and phosphorus available in the resources used to grow the fungus garden. From this experiment, I concluded that colony growth is primarily carbohydrate-limited.
ContributorsClark, Rebecca, 1981- (Author) / Fewell, Jennifer H (Thesis advisor) / Mueller, Ulrich (Committee member) / Liebig, Juergen (Committee member) / Elser, James (Committee member) / Harrison, Jon (Committee member) / Arizona State University (Publisher)
Created2011
Description
Many studies over the past two decades examined the link between climate patterns and discharge, but few have attempted to study the effects of the El Niño Southern Oscillation (ENSO) on localized and watershed specific processes such as nutrient loading in the Southwestern United States. The Multivariate ENSO Index (MEI) is used to describe the state of the ENSO, with positive (negative) values referring to an El Niño condition (La Niña condition). This study examined the connection between the MEI and precipitation, discharge, and total nitrogen (TN) and total phosphorus (TP) concentrations in the Upper Salt River Watershed in Arizona. Unrestricted regression models (UMs) and restricted regression models (RMs) were used to investigate the relationship between the discharges in Tonto Creek and the Salt River as functions of the magnitude of the MEI, precipitation, and season (winter/summer). The results suggest that in addition to precipitation, the MEI/season relationship is an important factor for predicting discharge. Additionally, high discharge events were associated with high magnitude ENSO events, both El Niño and La Niña. An UM including discharge and season, and a RM (restricting the seasonal factor to zero), were applied to TN and TP concentrations in the Salt River. Discharge and seasonality were significant factors describing the variability in TN in the Salt River while discharge alone was the significant factor describing TP. TN and TP in Roosevelt Lake were evaluated as functions of both discharge and MEI. Some significant correlations were found but internal nutrient cycling as well as seasonal stratification of the water column of the lake likely masks the true relationships. Based on these results, the MEI is a useful predictor of discharge, as well as nutrient loading in the Salt River Watershed through the Salt River and Tonto Creek. A predictive model investigating the effect of ENSO on nutrient loading through discharge can illustrate the effects of large scale climate patterns on smaller systems.
ContributorsSversvold, Darren (Author) / Neuer, Susanne (Thesis advisor) / Elser, James (Committee member) / Fenichel, Eli (Committee member) / Arizona State University (Publisher)
Created2012
Description
Land management practices such as domestic animal grazing can alter plant communities via changes in soil structure and chemistry, species composition, and plant nutrient content. These changes can affect the abundance and quality of plants consumed by insect herbivores with consequent changes in population dynamics. These population changes can translate to massive crop damage and pest control costs. My dissertation focused on Oedaleus asiaticus, a dominant Asian locust, and had three main objectives. First, I identified morphological, physiological, and behavioral characteristics of the migratory ("brown") and non-migratory ("green") phenotypes. I found that brown morphs had longer wings, larger thoraxes and higher metabolic rates compared to green morphs, suggesting that developmental plasticity allows greater migratory capacity in the brown morph of this locust. Second, I tested the hypothesis of a causal link between livestock overgrazing and an increase in migratory swarms of O. asiaticus. Current paradigms generally assume that increased plant nitrogen (N) should enhance herbivore performance by relieving protein-limitation, increasing herbivorous insect populations. I showed, in contrast to this scenario, that host plant N-enrichment and high protein artificial diets decreased the size and viability of O. asiaticus. Plant N content was lowest and locust abundance highest in heavily livestock-grazed fields where soils were N-depleted, likely due to enhanced erosion and leaching. These results suggest that heavy livestock grazing promotes outbreaks of this locust by reducing plant protein content. Third, I tested for the influence of dietary imbalance, in conjunction with high population density, on migratory plasticity. While high population density has clearly been shown to induce the migratory morph in several locusts, the effect of diet has been unclear. I found that locusts reared at high population density and fed unfertilized plants (i.e. high quality plants for O. asiaticus) had the greatest migratory capacity, and maintained a high percent of brown locusts. These results did not support the hypothesis that poor-quality resources increased expression of migratory phenotypes. This highlights a need to develop new theoretical frameworks for predicting how environmental factors will regulate migratory plasticity in locusts and perhaps other insects.
ContributorsCease, Arianne (Author) / Harrison, Jon (Thesis advisor) / Elser, James (Thesis advisor) / DeNardo, Dale (Committee member) / Quinlan, Michael (Committee member) / Sabo, John (Committee member) / Arizona State University (Publisher)
Created2012
Description
The greatest barrier to understanding how life interacts with its environment is the complexity in which biology operates. In this work, I present experimental designs, analysis methods, and visualization techniques to overcome the challenges of deciphering complex biological datasets. First, I examine an iron limitation transcriptome of Synechocystis sp. PCC 6803 using a new methodology. Until now, iron limitation in experiments of Synechocystis sp. PCC 6803 gene expression has been achieved through media chelation. Notably, chelation also reduces the bioavailability of other metals, whereas naturally occurring low iron settings likely result from a lack of iron influx and not as a result of chelation. The overall metabolic trends of previous studies are well-characterized but within those trends is significant variability in single gene expression responses. I compare previous transcriptomics analyses with our protocol that limits the addition of bioavailable iron to growth media to identify consistent gene expression signals resulting from iron limitation. Second, I describe a novel method of improving the reliability of centroid-linkage clustering results. The size and complexity of modern sequencing datasets often prohibit constructing distance matrices, which prevents the use of many common clustering algorithms. Centroid-linkage circumvents the need for a distance matrix, but has the adverse effect of producing input-order dependent results. In this chapter, I describe a method of cluster edge counting across iterated centroid-linkage results and reconstructing aggregate clusters from a ranked edge list without a distance matrix and input-order dependence. Finally, I introduce dendritic heat maps, a new figure type that visualizes heat map responses through expanding and contracting sequence clustering specificities. Heat maps are useful for comparing data across a range of possible states. However, data binning is sensitive to clustering cutoffs which are often arbitrarily introduced by researchers and can substantially change the heat map response of any single data point. With an understanding of how the architectural elements of dendrograms and heat maps affect data visualization, I have integrated their salient features to create a figure type aimed at viewing multiple levels of clustering cutoffs, allowing researchers to better understand the effects of environment on metabolism or phylogenetic lineages.
ContributorsKellom, Matthew (Author) / Raymond, Jason (Thesis advisor) / Anbar, Ariel (Committee member) / Elser, James (Committee member) / Shock, Everett (Committee member) / Walker, Sarah (Committee member) / Arizona State University (Publisher)
Created2017
Description
Television is currently in a changing state. There is no longer a singular broadcast format for series to follow. Streaming websites such as Netflix, Hulu, and Amazon Prime now release series in their entirety; this is known as a full-season release (FSR). Viewers are now able to act independently and determine the pace they wish to watch a new FSR series. This not only affects how fans engage in social television discussions on social media, but also changes the previously proposed viewer engagement model. Whereas previous research suggests that fans follow a static linear engagement model consisting of pre-communication, parallel communication, and post communication phases, fans are now able to move freely through viewer engagement phases. This creates a new type of engagement model: The Atomized Engagement Model. As fans move freely through the atomized engagement phases, they choose social media platforms to engage in fandom discussion. Research suggests that although there are distinct types of posts that occur in relation to social television discussions, the platforms used have a direct effect on the content and length of the post.
ContributorsPouls, Samantha Rae (Author) / Gilpin, Dawn (Thesis director) / Barrett, Marianne (Committee member) / Walter Cronkite School of Journalism and Mass Communication (Contributor) / School of Community Resources and Development (Contributor) / Barrett, The Honors College (Contributor)
Created2018-05
Description
This paper looks at the growth of influencer marketing in application and how it has shifted the relationship between brands and consumers. Barriers to enter the space and methods of practice are discussed and analyzed to project the accessibility of obtaining influencer status. Best practices for brands and influencers are outlined based on research, and key findings are analyzed from interviewed participants that play an active role in the field. Another component of the paper includes the discussion of the significance of platform dependence regarding influencers and brands using social media channels to reach consumers. The dynamic of the relationship that exists between consumers, brands and platforms is demonstrated through a model to demonstrate the interdependence of the relationship. The final component of the paper involves the exploration of the field as an active participant through an experiment that was conducted by the researcher on behalf of the question: can anyone be an influencer? The answer to this question is explored through personal accounts on the journey during an eight month process of testing content creation and promotion to build awareness and increase engagement. The barriers to enter the space as an influencer and to collaborate with brands is addressed through the process of testing tactics and strategies on social channels, along with travel expeditions across Arizona to contribute to content creation purposed into blog articles. The findings throughout the paper are conclusive that the value of influencer marketing is increasing as more brands validate and utilize this method in their marketing efforts.
ContributorsDavis, Natalie Marie (Author) / Giles, Bret (Thesis director) / Schlacter, John (Committee member) / Department of Information Systems (Contributor) / Department of Marketing (Contributor) / Walter Cronkite School of Journalism and Mass Communication (Contributor) / Barrett, The Honors College (Contributor)
Created2018-05
Description
As the U.S. reckons with the reality of sexual assault and harassment in the wake of the #MeToo movement, it is particularly important to consider sexual assault in the military, an institution that is a massive employer and the face of the U.S. abroad. Media coverage is a catalyst for change, and the nature and scope of coverage is indicative of public and political attitudes. This thesis uses both quantitative and qualitative data to analyze characteristics of military sexual assault cases that complicate media coverage and to identify strengths and weaknesses of the media's approach to such stories. On the quantitative side, it takes advantage of nearly 600 case reports of sexual assault from U.S. military bases in Japan that were categorized to identify themes such as disposition outcomes, alcohol involvement and victim participation in investigations. Qualitatively, this thesis includes interviews with military officials, victims' advocates, journalists and other stakeholders that help to create a more holistic understanding of how media cover military sexual assault. Notably, this thesis finds that a lack of public interest in the military, a lack of congruency between military and civilian systems, and a highly complex hierarchy that limits journalists' access to military sources and data all complicate coverage. Drawing from these conclusions, it recommends that the media avoid episodic reporting, focus on personalizing stories in an institutional context, embrace accountability journalism and dedicate resources to pursuing complex investigations. It also acknowledges the important role of non-traditional media in the future of information sharing on the topic of military sexual assault.
ContributorsArmstrong, Mia Anne (Author) / Warner, Carolyn (Thesis director) / Gilger, Kristin (Committee member) / Walter Cronkite School of Journalism and Mass Communication (Contributor) / School of Politics and Global Studies (Contributor) / Barrett, The Honors College (Contributor)
Created2018-05
Description
South Korea possesses the only culture to successfully create a transnationality and hybridity formula that is not replicable. So why Korea and why now? The goal of this thesis creative project is to demonstrate the marketing and communications strategies used in the arts and culture industry to drive global awareness and interest in K-Pop. In order to achieve that goal, I created HellotoHallyu.com, a website designed for an audience of Millennials and Generation Z English speakers to increase their awareness of the growth and impact of the Korean Wave in a fun and engaging way. So those who may hear a song by K-Pop idol group BTS on a music awards show in the U.S. can get themselves up-to-speed before diving into the fast-paced world of K-culture gossip sites and forums. Hello to Hallyu delivers consumer-friendly, educational content easily understood by English speakers with no prior knowledge of Korean culture, while still piquing the interest of K-pop connoisseurs. It provides the background necessary for even the most dedicated fans to glean new knowledge of Korea's cultural industry and a new perspective on the content they consume. Hello to Hallyu is based on a combination of secondary and primary research conducted over four semesters beginning Spring 2017 and continuing through Spring 2018. This project is set up as an ever-expanding resource freely available to anyone with internet access. The research required to maintain the site will continue with the Wave. However, the content currently on the site is evergreen, a documentation of the history of the Wave as explained in peer-reviewed articles and by Dr. Ingyu Oh as well as a documentation of my personal experience with Hallyu while in Korea and as a Westerner living in the U.S. The site's goal is to demonstrate the marketing and communications strategies used in the industry to drive global awareness and interest. Through this means, Hello to Hallyu aims to provide fully developed multimedia content intended to increase English speakers' awareness of the growth and impact of the Korean Wave as shown through site visits, content views, and audience engagement.
ContributorsTravis, Lisa Anne (Author) / Hass, Mark (Thesis director) / Shewell, Justin (Committee member) / Walter Cronkite School of Journalism and Mass Communication (Contributor) / School of Film, Dance and Theatre (Contributor) / Barrett, The Honors College (Contributor)
Created2018-05
Description
This thesis is a creative project involving video from all four years of my schooling at Arizona State University and the Walter Cronkite School of Journalism and Mass Communication. Entering the Cronkite School for the first time, I did not possess any knowledge about computer video editing software or any on-camera experience. The video pieces are various clips of some of my best work during my time at ASU, including reports on various sports/sporting events for Cronkite News and the Walter Cronkite Sports Network (WCSN). The project combines some of my best on-camera work, video editing skills, and even some new additions such as music under-beds to the pseudo-documentary. Overall, it demonstrates progression from a lack of knowledge about the basics of sports journalism to being cognizant about the multiple facets of the industry. While working on this thesis project, I quickly realized I needed to put all of my skills and knowledge to the test, as I had to incorporate many elements into a long video. For an introduction and closing, I needed to create a script that captured a chronological progression of the journey without detracting from the main focus: the reel. A huge thank you to both my thesis director and my second committee member for their assistance in helping me turn this idea into a reality. I took a chance when committing to Arizona State, but after four years in the desert, I can say with full confidence this was the absolute best choice I could have made.
ContributorsBaron, Michael (Author) / Dieffenbach, Paola (Thesis director) / Rhodes, Gail (Committee member) / Walter Cronkite School of Journalism and Mass Communication (Contributor) / Barrett, The Honors College (Contributor)
Created2018-05
Description
President Donald Trump announced his candidacy in June 2015, and the America immediately knew that he was an unorthodox candidate. Early on in his campaign, Trump isolated groups of people and treated them as enemies, but none so consistently as the news media. What began as criticism of "fake news," turned into calling the news media "the opposition party." However, media professionals agree that when the Trump administration called the news media the "enemy of the American people" \u2014 a line had been crossed. In the last two years Trump has denied simple fact and credible journalism countless times. His avid use of social media allows his messages to reach millions of people in moments - which had the potential to be a positive thing. However, Twitter is often where Trump turns to dispute the media, science, fact or anything else that "opposes" him. If Americans cannot believe the news media, cannot believe science, and cannot believe established fact, what can they believe? Allowing one man, in this case, Trump, to become the beacon of truth is dangerous and destructive to democracy. The news media must do their best to recapture the trust and faith of the American people by producing good, honest journalism. Seasoned journalism professionals say that his attacks on the media are likely a facade, just another way to appeal to his base, but that those attacks have the potential to wreak havoc in American society. Regardless of Trump's intentions, the toxicity between him and news media could have consequences that reach far beyond his presidency.
ContributorsPenningroth, Kendra Rene (Author) / Crane, Steve (Thesis director) / Downie, Leonard (Committee member) / Walter Cronkite School of Journalism and Mass Communication (Contributor) / School of Criminology and Criminal Justice (Contributor) / Barrett, The Honors College (Contributor)
Created2017-12