Matching Items (52)
Description
For over a century, researchers have been investigating collective cognition, in which a group of individuals together process information and act as a single cognitive unit. However, I still know little about circumstances under which groups achieve better (or worse) decisions than individuals. My dissertation research directly addressed this longstanding question, using the house-hunting ant Temnothorax rugatulus as a model system. Here I applied concepts and methods developed in psychology not only to individuals but also to colonies in order to investigate differences of their cognitive abilities. This approach is inspired by the superorganism concept, which sees a tightly integrated insect society as the analog of a single organism. I combined experimental manipulations and models to elucidate the emergent processes of collective cognition. My studies show that groups can achieve superior cognition by sharing the burden of option assessment among members and by integrating information from members using positive feedback. However, the same positive feedback can lock the group into a suboptimal choice in certain circumstances. Although ants are obligately social, my results show that they can be isolated and individually tested on cognitive tasks. In the future, this novel approach will help the field of animal behavior move towards better understanding of collective cognition.
ContributorsSasaki, Takao (Author) / Pratt, Stephen C (Thesis advisor) / Amazeen, Polemnia (Committee member) / Liebig, Jürgen (Committee member) / Janssen, Marco (Committee member) / Fewell, Jennifer (Committee member) / Hölldobler, Bert (Committee member) / Arizona State University (Publisher)
Created2013
Description
The spread of invasive species may be greatly affected by human responses to prior species spread, but models and estimation methods seldom explicitly consider human responses. I investigate the effects of management responses on estimates of invasive species spread rates. To do this, I create an agent-based simulation model of an insect invasion across a county-level citrus landscape. My model provides an approximation of a complex spatial environment while allowing the "truth" to be known. The modeled environment consists of citrus orchards with insect pests dispersing among them. Insects move across the simulation environment infesting orchards, while orchard managers respond by administering insecticide according to analyst-selected behavior profiles and management responses may depend on prior invasion states. Dispersal data is generated in each simulation and used to calculate spread rate via a set of estimators selected for their predominance in the empirical literature. Spread rate is a mechanistic, emergent phenomenon measured at the population level caused by a suite of latent biological, environmental, and anthropogenic. I test the effectiveness of orchard behavior profiles on invasion suppression and evaluate the robustness of the estimators given orchard responses. I find that allowing growers to use future expectations of spread in management decisions leads to reduced spread rates. Acting in a preventative manner by applying insecticide before insects are actually present, orchards are able to lower spread rates more than by reactive behavior alone. Spread rates are highly sensitive to spatial configuration. Spatial configuration is hardly a random process, consisting of many latent factors often not accounted for in spread rate estimation. Not considering these factors may lead to an omitted variables bias and skew estimation results. The ability of spread rate estimators to predict future spread varies considerably between estimators, and with spatial configuration, invader biological parameters, and orchard behavior profile. The model suggests that understanding the latent factors inherent to dispersal is important for selecting phenomenological models of spread and interpreting estimation results. This indicates a need for caution when evaluating spread. Although standard practice, current empirical estimators may both over- and underestimate spread rate in the simulation.
ContributorsShanafelt, David William (Author) / Fenichel, Eli P (Thesis advisor) / Richards, Timothy (Committee member) / Janssen, Marco (Committee member) / Arizona State University (Publisher)
Created2012
DescriptionThis paper provides an analysis of the differences in impacts made by companies that promote their sustainability efforts. A comparison of companies reveals that the ones with greater supply chain influence and larger consumer bases can make more concrete progress in terms of accomplishment for the sustainability realm.
ContributorsBeaubien, Courtney Lynn (Author) / Anderies, John (Thesis director) / Allenby, Brad (Committee member) / Janssen, Marco (Committee member) / Barrett, The Honors College (Contributor) / School of Life Sciences (Contributor)
Created2013-05
Description
The evolution of cooperation is a fundamental problem in biology, especially for non-relatives, where indirect fitness benefits cannot counter within-group inequalities. Multilevel selection models show how cooperation can evolve if it generates a group-level advantage, even when cooperators are disadvantaged within their group. This allows the possibility of group selection, but few examples have been described in nature. Here we show that group selection can explain the evolution of cooperative nest founding in the harvester ant Pogonomyrmex californicus. Through most of this species’ range, colonies are founded by single queens, but in some populations nests are instead founded by cooperative groups of unrelated queens. In mixed groups of cooperative and single-founding queens, we found that aggressive individuals had a survival advantage within their nest, but foundress groups with such non-cooperators died out more often than those with only cooperative members. An agent-based model shows that the between-group advantage of the cooperative phenotype drives it to fixation, despite its within-group disadvantage, but only when population density is high enough to make between-group competition intense. Field data show higher nest density in a population where cooperative founding is common, consistent with greater density driving the evolution of cooperative foundation through group selection.
ContributorsShaffer, Zachary (Author) / Sasaki, Takao (Author) / Haney, Brian (Author) / Janssen, Marco (Author) / Pratt, Stephen (Author) / Fewell, Jennifer (Author) / College of Liberal Arts and Sciences (Contributor)
Created2016-07-28
Description
Celiac Disease (CD) is now widespread as one in 133 people are currently diagnosed, while there were only one in 150 in 2006. Much of the research concerning CD is still in the early stages, as formal epidemiological studies are relatively recent. CD is aggravated by the consumption of gluten, which is found mainly in wheat, rye, oats, and barley. Not surprisingly, the rising prevalence of CD has created a significant business opportunity for food manufacturers in developing products that are tailored to CD sufferers. While the entire Gluten-Free (GF) industry has been experiencing double digit growth rates, the expansion in available snack foods has outstripped all others. Observation of GF snack food prices suggests that food manufacturers are responding to high retail prices associated with GF foods. However, GF foods are often also advertised with other attributes that generally sell for a premium over conventional foods. Therefore, whether the high retail price for GF snack foods can be attributed specifically to the GF attribute is an empirical question. The objective of this research is to determine whether there is a retail-price premium for GF snack foods and, if there is, to estimate its magnitude. A hedonic pricing model is used to answer this question. Specifically, a hedonic pricing model was applied to a unique dataset of snack food products in order to estimate the marginal value for the GF attribute, while controlling for a number of other important attributes. Results show that the GF attribute is both economically and statistically significant, implying a premium of nearly $1.86 above gluten-containing products. Production costs for smaller manufacturers can be two to three times higher for GF foods relative to non-GF foods, but this still implies an excess premium of over $0.50 (assuming 40% margins). However, high premiums may not last as large retailers are utilizing their influence over suppliers to keep retail margins low. Therefore, the primary implication of the research is that the rapid growth in recent years can easily be explained on economic grounds for large agribusinesses, as this implies a major profit opportunity.
ContributorsSampson, Jed Philip (Author) / Richards, Timothy (Thesis advisor) / Manfredo, Mark (Committee member) / Pofahl, Geoffrey (Committee member) / Arizona State University (Publisher)
Created2010
Description
Climate change presents the urgent need for effective sustainable water management that is capable of preserving natural resources while maintaining economical stability. States like California rely heavily on groundwater pumping for agricultural use, contributing to land subsidence and insufficient returns to water resources. The recent California drought has impacted agricultural production of certain crops. In this thesis, we present an agent-based model of farmers adapting to drought conditions by making crop choice decisions, much like the decisions Californian farmers have made. We use the Netlogo platform to capture the 2D spatial view of an agricultural system with changes in annual rainfall due to drought conditions. The goal of this model is to understand some of the simple rules farmers may follow to self-govern their consumption of a water resource. Farmer agents make their crop decisions based on deficit irrigation crop production function and a net present value discount rate. The farmers choose between a thirsty crop with a high production cost and a dry crop with a low production cost. Simulations results show that farmers switch crops in accordance with limited water and land resources. Farmers can maintain profit and yield by following simple rules of crop switching based on future yields and optimal irrigation. In drought conditions, individual agents expecting lower annual rainfall were able to increase their total profits. The maintenance of crop yield and profit is evidence of successful adaptation when farmers switch to crops that require less water.
ContributorsGokool, Rachael Shanta (Author) / Janssen, Marco (Thesis director) / Eakin, Hallie (Committee member) / School of Human Evolution and Social Change (Contributor) / Barrett, The Honors College (Contributor)
Created2016-05
Description
As one of the root causes of chronic hunger, it is well-established that food insecurity adversely affects health and economic outcomes of those afflicted (Carmichael et al. 2007; Seligman et al. 2009; Huang, Matta Oshima, and Kim, 2010; Pan et al. 2012; Martinez et al. 2018). More than eleven percent of Americans, uncertain about where their next meal will come from, experienced some degree of food insecurity in 2018 (Coleman-Jensen, 2019). Programs like SNAP and WIC have not only proven to be effective in providing food for households, but they can serve as an example for other countries that struggle to help citizens meet their dietary needs (Gundersen, 2019). non-government entities like food banks and food pantries have played an increasingly important role in addressing food insecurity. While there is a perception that food banks and pantries are only emergency resources, evidence suggests that many individuals regularly rely on private hunger relief organizations for food (Paynter et al., 2011; Kicinski, 2012). Food banks play a crucially important role in distributing food and are uniquely positioned to alleviate hunger. However, these private organizations have been shown, compared to public food assistance programs, to be less effective at specifically addressing the issue of food insecurity (Bazerghi et al., 2016; Loopstra & Tarasuk, 2012; Ratcliffe & McKernan, 2010; Metallinos-Katsaras et al., 2010). Existing research has largely focused on the characteristics of food pantry clients generally, without exploring the socio-economic and experiential variation within this group (Towers, 2009; Kicinski, 2012; Gundersen el al., 2017). This study fills a gap in the literature by examining the characteristics of food pantry users, and how they compare to those not using food pantries but still face food insecurity, using nationally representative survey data. Additionally, I explore whether food pantries and public food assistance programs might be “bundled” together. I focus on gradients of economic vulnerability by examining households who participate in public food assistance programs, are SNAP-eligible but not participating, as well as households who bundle both private and public food assistance to meet their food needs. With this thesis, I hope to contribute this research by providing behavioral insights into understanding the role that food banks play in mitigating challenges associated with food insecurity among US households.
ContributorsLongo, John David (Author) / Chenarides, Lauren (Thesis director) / Richards, Timothy (Committee member) / Economics Program in CLAS (Contributor) / Department of English (Contributor) / Barrett, The Honors College (Contributor)
Created2020-05
Description
The goal of this project is to improve the efficiency of operations for Quincea Social Enterprise. I aim to achieve this goal by interviewing market participants to make recommendations for how Quincea Social Enterprise can best utilize resources to deliver vegetables, fruits and herbs to their key institutional customers (schools, churches, hospitals, group homes and corporate cafeterias). This thesis views Quincea through the lens of the Social Enterprise Business Model and compares its organization to serve underemployed groups including veterans and adults with intellectual and/or developmental disabilities (IDD Adults) 1. Throughout my research, I use supply chain theory and network structure to inform supply chain strategy, optimize logistics, and integrate the supply chain organization, processes and technology. My insights are grounded in the supply chain literature, and a comparison with other non-profit operations. This thesis identifies the resources, capabilities, and partnerships needed for a successful social enterprise. The key findings include: a) Quincea’s unique business model exhibits promising potential for cost-effectively creations of jobs for adults with intellectual and/or developmental disabilities; b) an important strength is the depth of its public and private sector strategic partnerships; c) another important organizational advantage is its emphasis on operational efficiencies and being price competitive, rather than having its social mission drive sales d) its efforts to document its strategies and operating plans, along with securing many partnerships with national corporations, should facilitate program geographic expansion; e) the emphasis on social impact metrics should make it easier to measure program effectiveness and to attract additional strategic partners; and f) the economic self-sustaining business model exhibits promising potential to expand operations, while having reduced dependency on government, foundation and individual donor subsidies to scale operations.
ContributorsStephens, Natalie (Author) / Richards, Timothy (Thesis director) / Hall, Jonathan (Committee member) / Department of Supply Chain Management (Contributor) / Barrett, The Honors College (Contributor)
Created2019-05
Description
Coffee is an important link between the United States and Latin America and an important part of Latin America’s culture and economy. This paper looks at the similarities and differences between coffee organizations in Colombia, Ecuador, Peru, and Guatemala. Colombia has the strongest coffee organizations with the most political power. Guatemala and Peru, to a lesser extent, have well organized and powerful organizations that make up their industry. However, Ecuador has a significantly less organized organization. At their core, each country has a similar structure. There is one organization on the national level that watches out for the industry as a whole. Underneath that, there are smaller, often regional organizations made up of cooperatives pooling their resources for export. They function in similar ways as the national organizations, but have less reach. At the bottom, there are individual cooperatives and independent farmers. These cooperatives do not have much reach or connection to international markets.
ContributorsChabin, James Edward (Author) / Janssen, Marco (Thesis director) / Taylor, Keith (Committee member) / School of Sustainability (Contributor) / School of International Letters and Cultures (Contributor, Contributor) / Barrett, The Honors College (Contributor)
Created2020-05
Description
This study examined perception of K12 schooling systems as experienced by a randomsample of adults in Phoenix, AZ. It explored whether the values purported as key factors
in the American K12 schooling system - as presented in academic literature - were compatible with the lives, interests and goals of ‘users’, student-participants. In addition, it offered opportunity for post-K12 student-participants to share their views on the purposes, goals, and outcomes they held to be important. The sample consisted of 139 post-K12 stu-
dents/individuals residing in Phoenix, AZ. Mean age of student-participants was 29. Results indicated a mismatch between purported K12 schooling goals and important outcomes embedded in the system and values held by the K12 student-participants. The participants in this research generally perceived K12 schooling as valuable, both to themselves and to society at large, but stressed that the deficiencies they perceived in the system were particular to delivery platforms as they relate to the learning styles of students and belonging. Future life skills and success - in and after K12 schooling - whether related to college or not were also of importance. Results revealed that the initial hypothesis of income, age, and ethnicity as
key factors in satisfaction with K12 schooling was not borne-out. Rather it revealed that a sense of belonging and the suitability of learning platforms to the individual learning styles of students were of greatest significance.
ContributorsParker-Anderies, Margaret (Author) / Janssen, Marco (Thesis advisor) / Garcia, David (Committee member) / Mishra, Punya (Committee member) / Arizona State University (Publisher)
Created2022