Matching Items (488)

Filtering by

Clear all filters

149729-Thumbnail Image.png

The emergence and scaling of division of labor in insect societies

Description

Division of labor, whereby different group members perform different functions, is a fundamental attribute of sociality. It appears across social systems, from simple cooperative groups to complex eusocial colonies. A core challenge in sociobiology is to explain how patterns of

Division of labor, whereby different group members perform different functions, is a fundamental attribute of sociality. It appears across social systems, from simple cooperative groups to complex eusocial colonies. A core challenge in sociobiology is to explain how patterns of collective organization are generated. Theoretical models propose that division of labor self-organizes, or emerges, from interactions among group members and the environment; division of labor is also predicted to scale positively with group size. I empirically investigated the emergence and scaling of division of labor in evolutionarily incipient groups of sweat bees and in eusocial colonies of harvester ants. To test whether division of labor is an emergent property of group living during early social evolution, I created de novo communal groups of the normally solitary sweat bee Lasioglossum (Ctenonomia) NDA-1. A division of labor repeatedly arose between nest excavation and guarding tasks; results were consistent with hypothesized effects of spatial organization and intrinsic behavioral variability. Moreover, an experimental increase in group size spontaneously promoted higher task specialization and division of labor. Next, I examined the influence of colony size on division of labor in larger, more integrated colonies of the harvester ant Pogonomyrmex californicus. Division of labor scaled positively with colony size in two contexts: during early colony ontogeny, as colonies grew from tens to hundreds of workers, and among same-aged colonies that varied naturally in size. However, manipulation of colony size did not elicit a short-term response, suggesting that the scaling of division of labor in P. californicus colonies is a product of functional integration and underlying developmental processes, rather than a purely emergent epiphenomenon. This research provides novel insights into the organization of work in insect societies, and raises broader questions about the role of size in sociobiology.

Contributors

Agent

Created

Date Created
2011

149681-Thumbnail Image.png

Creep characteristics and shear strength of recycled asphalt blends

Description

The trend towards using recycled materials on new construction projects is growing as the cost for construction materials are ever increasing and the awareness of the responsibility we have to be good stewards of our environment is heightened. While recycled

The trend towards using recycled materials on new construction projects is growing as the cost for construction materials are ever increasing and the awareness of the responsibility we have to be good stewards of our environment is heightened. While recycled asphalt is sometimes used in pavements, its use as structural fill has been hindered by concern that it is susceptible to large long-term deformations (creep), preventing its use for a great many geotechnical applications. While asphalt/soil blends are often proposed as an alternative to 100% recycled asphalt fill, little data is available characterizing the geotechnical properties of recycled asphalt soil blends. In this dissertation, the geotechnical properties for five different recycled asphalt soil blends are characterized. Data includes the particle size distribution, plasticity index, creep, and shear strength for each blend. Blends with 0%, 25%, 50%, 75% and 100% recycled asphalt were tested. As the recycled asphalt material used for testing had particles sizes up to 1.5 inches, a large 18 inch diameter direct shear apparatus was used to determine the shear strength and creep characteristics of the material. The results of the testing program confirm that the creep potential of recycled asphalt is a geotechnical concern when the material is subjected to loads greater than 1500 pounds per square foot (psf). In addition, the test results demonstrate that the amount of soil blended with the recycled asphalt can greatly influence the creep and shear strength behavior of the composite material. Furthermore, there appears to be an optimal blend ratio where the composite material had better properties than either the recycled asphalt or virgin soil alone with respect to shear strength.

Contributors

Agent

Created

Date Created
2011

149684-Thumbnail Image.png

Global bioethics: a descriptive analysis of the function of bioethics in health and medicine on a global scale

Description

This thesis explores concept of "global bioethics" in both its development as well as its current state in an effort to understand exactly where it fits into the larger field of bioethics. Further, the analysis poses specific questions regarding what

This thesis explores concept of "global bioethics" in both its development as well as its current state in an effort to understand exactly where it fits into the larger field of bioethics. Further, the analysis poses specific questions regarding what it may contribute to this field and related fields, and the possibility and scope associated with the continued development of global bioethics as its own discipline. To achieve this, the piece addresses questions regarding current opinions on the subject, the authorities and their associated publications related to global bioethics, and what the aims of the subject should be given its current state. "Global Bioethics" is a term that, while seen frequently in bioethics literature, is difficult to define succinctly. While many opinions are provided on the concept, little consensus exists regarding its application and possible contributions and, in some cases, even its very possibility. Applying ethical principles of health and medicine globally is undoubtedly complicated by the cultural, social, and geographical considerations associated with understanding health and medicine in different populations, leading to a dichotomy between two schools of thought in relation to global bioethics. These two sides consist of those who think that universality of bioethics is possible whereas the opposing viewpoint holds that relativism is the key to applying ethics on a global scale. Despite the aforementioned dichotomy in addressing applications of global bioethics, this analysis shows that the goals of the subject should be more focused on contributing to ethical frameworks and valuable types of thinking related to the ethics health and medicine on a global scale. This is achieved through an exploration of bioethics in general, health as a function of society and culture, the history and development of global bioethics itself, and an exploration of pertinent global health topics. While primarily descriptive in nature, this analysis critiques some of the current discussions and purported goals surrounding global bioethics, recommending that the field focus on fostering valuable discussion and framing of issues rather than the pursuit of concrete judgments on moral issues in global health and medicine.

Contributors

Agent

Created

Date Created
2011

149861-Thumbnail Image.png

Community supported agriculture membership: characterizing food and sustainability behaviors

Description

Community Supported Agriculture programs (CSAs) have become a viable local source of fresh agricultural goods and represent a potentially new way to improve fruit and vegetable consumption among individuals and families. Studies concerning CSAs have focused mainly on characteristics of

Community Supported Agriculture programs (CSAs) have become a viable local source of fresh agricultural goods and represent a potentially new way to improve fruit and vegetable consumption among individuals and families. Studies concerning CSAs have focused mainly on characteristics of the typical CSA member and motivations and barriers to join a CSA program. The purpose of this study was to examine whether behavior and attitudinal differences existed between current CSA members and a nonmember control group. Specifically, ecological attitudes, eating out behaviors, composting frequency, and family participation in food preparation were assessed. This study utilized an online survey comprising items from previous survey research as well as newly created items. A total of 115 CSA member and 233 control survey responses were collected. CSA members were more likely to be older, have more education, and have a higher income than the control group. The majority of CSA members surveyed were female, identified as non-Hispanic and Caucasian, earned a higher income, and reported being the primary food shopper and preparer. The majority of members also noted that the amount and variety of fruits and vegetables they ate and served their family increased as a result of joining a CSA. CSA members were more ecologically minded compared to the control group. Frequency of eating out was not significantly different between groups. However, eating out behaviors were different between income categories. CSA members spent significantly more money at each meal eaten away from home and spent significantly more money on eating out each week. In both cases, controlling for income attenuated differences between groups. CSA members composted at a significantly higher rate and took part in other eco-friendly behaviors more often than the control group. Finally, no significant difference was evident between the two groups when analyzing family involvement in food preparation and meal decision-making. Overall, some significant attitudinal and behavioral differences existed between CSA members and non-CSA members. Further research is necessary to examine other distinctions between the two groups and whether these differences occur as a result of CSA membership.

Contributors

Agent

Created

Date Created
2011

149869-Thumbnail Image.png

Constructing a model for small scale fish farmers

Description

Fish farming is a fast growing industry, which, although necessary to feed an ever growing worldwide population, has its share of negative environmental consequences, including the release of drugs and other waste into the ocean, the use of fish caught

Fish farming is a fast growing industry, which, although necessary to feed an ever growing worldwide population, has its share of negative environmental consequences, including the release of drugs and other waste into the ocean, the use of fish caught from the ocean to feed farm raised fish, and the escape of farm raised fish into natural bodies of water. However, the raising of certain types of fish, such as tilapia, seems to be an environmentally better proposition than raising other types of fish, such as salmon. This paper will explore the problems associated with fish farming, as well as offer a model, based on the literature, and interviews with fish farmers, to make small-scale fish farming both more environmentally, and more economically, sustainable. This paper culminates with a model for small-scale, specifically semi-subsistence, fish farmers. This model emphasizes education of the fish farmers, as well as educators learning from the fish farmers they interact with. The goal of this model is to help these fish farmers become both more environmentally and economically sustainable.

Contributors

Agent

Created

Date Created
2011

149716-Thumbnail Image.png

Operationalizing neighborhood resiliency: a grass-roots approach

Description

This research addresses the ability for neighborhoods to assess resiliency as it applies to their respective local areas. Two demographically and economically contrasting neighborhoods in Glendale, Arizona were studied to understand what residents' value and how those values link to

This research addresses the ability for neighborhoods to assess resiliency as it applies to their respective local areas. Two demographically and economically contrasting neighborhoods in Glendale, Arizona were studied to understand what residents' value and how those values link to key principles of resiliency. Through this exploratory research, a community-focused process was created to use these values in order to link them to key principles of resiliency and potential measureable indicators. A literature review was conducted to first assess definitions and key principles of resiliency. Second, it explored cases of neighborhoods or communities that faced a pressure or disaster and responded resiliently based on these general principles. Each case study demonstrated that resiliency at the neighborhood level was important to its ability to survive its respective pressure and emerge stronger. The Heart of Glendale and Thunderbird Palms were the two neighborhoods chosen to test the ability to operationalize neighborhood resiliency in the form of indicators. First, an in-depth interview was conducted with a neighborhood expert to understand each area's strengths and weaknesses and get a context for the neighborhood and how it has developed. Second, a visioning session was conducted with each neighborhood consisting of seven participants to discuss its values and how they relate to key principles of resiliency. The values were analyzed and used to shape locally relevant indicators. The results of this study found that the process of identifying participants' values and linking them to key principles of resiliency is a viable methodology for measuring neighborhood resiliency. It also found that indicators and values differed between the Heart of Glendale, a more economically vulnerable yet ethnically diverse area, than Thunderbird Palms, a more racially homogenous, middle income neighborhood. The Heart of Glendale valued the development of social capital more than Thunderbird Palms which placed a higher value on the condition of the built environment as a vehicle for stimulating vibrancy and resiliency in the neighborhood. However, both neighborhoods highly valued public education and providing opportunities for children to be future leaders in their local communities.

Contributors

Agent

Created

Date Created
2011

149717-Thumbnail Image.png

Comparison of soil and vegetation properties using salt extractor and conventional soil amendments from irrigation with coal bed natural gas product water

Description

Coal bed natural gas (CBNG) production has become a significant contribution to the nation's energy supply. Large volumes of water are generated as a byproduct of CBNG extraction, of which this "product water" is relatively high in sodium. High sodicity

Coal bed natural gas (CBNG) production has become a significant contribution to the nation's energy supply. Large volumes of water are generated as a byproduct of CBNG extraction, of which this "product water" is relatively high in sodium. High sodicity reduces water quality and limits environmentally compliant disposal options for producers. Crop irrigation with CBNG product water complies with state and federal laws and is a disposal method that also provides a beneficial use to private landowners. However, this disposal method typically requires gypsum and sulfur soil amendments due to the high levels of sodium in the water, which can reduce soil infiltration and hydraulic conductivity. In this study, I tested a new product called Salt Extractor that was marketed to CBNG producers to ameliorate the negative effects of high sodicity. The experiment was conducted in the Powder River Basin of Wyoming. I used a random block design to compare the soil and vegetation properties of plots following application with CBNG product water and treatments of either Salt Extractor, gypsum and sulfur (conventional), or no treatment (control). Data was analyzed by comparing the amount of change between treatments after watering. Results demonstrated the known ability of gypsum and sulfur to lower the relative sodicity of the soil. Plots treated with Salt Extractor, however, did not improve relative levels of sodicity and exhibited no favorable benefits to vegetation.

Contributors

Agent

Created

Date Created
2011

149718-Thumbnail Image.png

Community food resource assessment in Central City South, Phoenix: a study of community capacity building

Description

Many studies have shown that access to healthy food in the US is unevenly distributed and that supermarkets and other fresh food retailers are less likely to be located in low-income minority communities, where convenience and dollar stores are more

Many studies have shown that access to healthy food in the US is unevenly distributed and that supermarkets and other fresh food retailers are less likely to be located in low-income minority communities, where convenience and dollar stores are more prevalent grocery options. I formed a partnership with Phoenix Revitalization Corporation, a local community development organization engaged in Central City South, Phoenix, to enhance the community's capacity to meet its community health goals by improving access to healthy food. I used a community-based participatory approach that blended qualitative and quantitative elements to accommodate collaboration between both academic and non-academic partners. Utilizing stakeholder interviews, Nutrition Environment Measures Surveys (NEMS), and mapping to analyze the community's food resources, research revealed that the community lacks adequate access to affordable, nutritious food. Community food stores (n=14) scored an average of 10.9 out of a possible 54 points using the NEMS scoring protocol. The community food assessment is an essential step in improving access to healthy food for CCS residents and provides a baseline for tracking progress to improve residents' food access. Recommendations were drafted by the research partnership to equip and empower the community with strategic, community-specific interventions based on the research findings.

Contributors

Agent

Created

Date Created
2011

149725-Thumbnail Image.png

Molecular chaperones of the endoplasmic reticulum promote hepatitis C virus E2 protein production in plants

Description

Infections caused by the Hepatitis C Virus (HCV) are very common worldwide, affecting up to 3% of the population. Chronic infection of HCV may develop into liver cirrhosis and liver cancer which is among the top five of the most

Infections caused by the Hepatitis C Virus (HCV) are very common worldwide, affecting up to 3% of the population. Chronic infection of HCV may develop into liver cirrhosis and liver cancer which is among the top five of the most common cancers. Therefore, vaccines against HCV are under intense study in order to prevent HCV from harming people's health. The envelope protein 2 (E2) of HCV is thought to be a promising vaccine candidate because it can directly bind to a human cell receptor and plays a role in viral entry. However, the E2 protein production in cells is inefficient due to its complicated matured structure. Folding of E2 in the endoplasmic reticulum (ER) is often error-prone, resulting in production of aggregates and misfolded proteins. These incorrect forms of E2 are not functional because they are not able to bind to human cells and stimulate antibody response to inhibit this binding. This study is aimed to overcome the difficulties of HCV E2 production in plant system. Protein folding in the ER requires great assistance from molecular chaperones. Thus, in this study, two molecular chaperones in the ER, calreticulin and calnexin, were transiently overexpressed in plant leaves in order to facilitate E2 folding and production. Both of them showed benefits in increasing the yield of E2 and improving the quality of E2. In addition, poorly folded E2 accumulated in the ER may cause stress in the ER and trigger transcriptional activation of ER molecular chaperones. Therefore, a transcription factor involved in this pathway, named bZIP60, was also overexpressed in plant leaves, aiming at up-regulating a major family of molecular chaperones called BiP to assist protein folding. However, our results showed that BiP mRNA levels were not up-regulated by bZIP60, but they increased in response to E2 expression. The Western blot analysis also showed that overexpression of bZIP60 had a small effect on promoting E2 folding. Overall, this study suggested that increasing the level of specific ER molecular chaperones was an effective way to promote HCV E2 protein production and maturation.

Contributors

Agent

Created

Date Created
2011

149757-Thumbnail Image.png

Sustainable water management in Ciudad Juarez

Description

ABSTRACT Water resources in many parts of the world are subject to increasing stress because of (a) the growth in demand caused by population increase and economic development, (b) threats to supply caused by climate and land cover change, and

ABSTRACT Water resources in many parts of the world are subject to increasing stress because of (a) the growth in demand caused by population increase and economic development, (b) threats to supply caused by climate and land cover change, and (c) a heightened awareness of the importance of maintaining water supplies to other parts of the ecosystem. An additional factor is the quality of water management. The United States-Mexican border provides an example of poor water management combined with increasing demand for water resources that are both scarce and uncertain. This dissertation focuses on the problem of water management in the border city of Ciudad Juarez, Chihuahua. The city has attracted foreign investment during the last few decades, largely due to relatively low environmental and labor costs, and to a range of tax incentives and concessions. This has led to economic and population growth, but also to higher demand for public services such as water which leads to congestion and scarcity. In particular, as water resources have become scarce, the cost of water supply has increased. The dissertation analyzes the conditions that allow for the efficient use of water resources at sustainable levels of economic activity--i.e., employment and investment. In particular, it analyzes the water management strategies that lead to an efficient and sustainable use of water when the source of water is either an aquifer, or there is conjunctive use of ground and imported water. The first part of the dissertation constructs a model of the interactive effects of water supply, wage rates, inward migration of labor and inward investment of capital. It shows how growing water scarcity affects population growth through the impact it has on real wage rates, and how this erodes the comparative advantage of Ciudad Juarez--low wages--to the point where foreign investment stops. This reveals the very close connection between water management and the level of economic activity in Ciudad Juarez. The second part of the dissertation examines the effect of sustainable and efficient water management strategies on population and economic activity levels under two different settings. In the first Ciudad Juarez relies exclusively on ground water to meet demand--this reflects the current situation of Ciudad Juarez. In the second Ciudad Juarez is able both to import water and to draw on aquifers to meet demand. This situation is motivated by the fact that Ciudad Juarez is considering importing water from elsewhere to maintain its economic growth and mitigate the overdraft of the Bolson del Hueco aquifer. Both models were calibrated on data for Ciudad Juarez, and then used to run experiments with respect to different environmental and economic conditions, and different water management options. It is shown that for a given set of technological, institutional and environmental conditions, the way water is managed in a desert environment determines the long run equilibrium levels of employment, investment and output. It is also shown that the efficiency of water management is consistent with the sustainability of water use and economic activity. Importing water could allow the economy to operate at higher levels of activity than where it relies solely on local aquifers. However, at some scale, water availability will limit the level of economic activity, and the disposable income of the residents of Ciudad Juarez.

Contributors

Agent

Created

Date Created
2011