Matching Items (164)
Description
Preserving a system’s viability in the presence of diversity erosion is critical if the goal is to sustainably support biodiversity. Reduction in population heterogeneity, whether inter- or intraspecies, may increase population fragility, either decreasing its ability to adapt effectively to environmental changes or facilitating the survival and success of ordinarily rare phenotypes. The latter may result in over-representation of individuals who may participate in resource utilization patterns that can lead to over-exploitation, exhaustion, and, ultimately, collapse of both the resource and the population that depends on it. Here, we aim to identify regimes that can signal whether a consumer–resource system is capable of supporting viable degrees of heterogeneity. The framework used here is an expansion of a previously introduced consumer–resource type system of a population of individuals classified by their resource consumption. Application of the Reduction Theorem to the system enables us to evaluate the health of the system through tracking both the mean value of the parameter of resource (over)consumption, and the population variance, as both change over time. The article concludes with a discussion that highlights applicability of the proposed system to investigation of systems that are affected by particularly devastating overly adapted populations, namely cancerous cells. Potential intervention approaches for system management are discussed in the context of cancer therapies.
ContributorsKareva, Irina (Author) / Morin, Benjamin (Author) / Castillo-Chavez, Carlos (Author) / Simon M. Levin Mathematical, Computational and Modeling Sciences Center (Contributor) / College of Liberal Arts and Sciences (Contributor) / School of Human Evolution and Social Change (Contributor) / Julie Ann Wrigley Global Institute of Sustainability (Contributor)
Created2015-02-01
Description
Evolving Earth observation and change detection techniques enable the automatic identification of Land Use and Land Cover Change (LULCC) over a large extent from massive amounts of remote sensing data. It at the same time poses a major challenge in effective organization, representation and modeling of such information. This study proposes and implements an integrated computational framework to support the modeling, semantic and spatial reasoning of change information with regard to space, time and topology. We first proposed a conceptual model to formally represent the spatiotemporal variation of change data, which is essential knowledge to support various environmental and social studies, such as deforestation and urbanization studies. Then, a spatial ontology was created to encode these semantic spatiotemporal data in a machine-understandable format. Based on the knowledge defined in the ontology and related reasoning rules, a semantic platform was developed to support the semantic query and change trajectory reasoning of areas with LULCC. This semantic platform is innovative, as it integrates semantic and spatial reasoning into a coherent computational and operational software framework to support automated semantic analysis of time series data that can go beyond LULC datasets. In addition, this system scales well as the amount of data increases, validated by a number of experimental results. This work contributes significantly to both the geospatial Semantic Web and GIScience communities in terms of the establishment of the (web-based) semantic platform for collaborative question answering and decision-making.
ContributorsVadjunec, Jacqueline M. (Author) / Radel, Claudia (Author) / Turner II, B. L. (Author) / College of Liberal Arts and Sciences (Contributor) / School of Geographical Sciences and Urban Planning (Contributor) / Julie Ann Wrigley Global Institute of Sustainability (Contributor) / School of Sustainability (Contributor)
Created2016-10-25
Description
The growth rate hypothesis (GRH) proposes that higher growth rate (the rate of change in biomass per unit biomass, μ) is associated with higher P concentration and lower C∶P and N∶P ratios. However, the applicability of the GRH to vascular plants is not well-studied and few studies have been done on belowground biomass. Here we showed that, for aboveground, belowground and total biomass of three study species, μ was positively correlated with N∶C under N limitation and positively correlated with P∶C under P limitation. However, the N∶P ratio was a unimodal function of μ, increasing for small values of μ, reaching a maximum, and then decreasing. The range of variations in μ was positively correlated with variation in C∶N∶P stoichiometry. Furthermore, μ and C∶N∶P ranges for aboveground biomass were negatively correlated with those for belowground. Our results confirm the well-known association of growth rate with tissue concentration of the limiting nutrient and provide empirical support for recent theoretical formulations.
ContributorsYu, Qiang (Author) / Wu, Honghui (Author) / He, Nianpeng (Author) / Lu, Xiaotao (Author) / Wang, Zhiping (Author) / Elser, James (Author) / Wu, Jianguo (Author) / Han, Xingguo (Author) / College of Liberal Arts and Sciences (Contributor) / School of Life Sciences (Contributor) / Julie Ann Wrigley Global Institute of Sustainability (Contributor) / School of Sustainability (Contributor)
Created2012-03-13
Grasshoppers Regulate N: P Stoichiometric Homeostasis by Changing Phosphorus Contents in Their Frass
Description
Nitrogen (N) and phosphorus (P) are important limiting nutrients for plant production and consumer performance in a variety of ecosystems. As a result, the N:P stoichiometry of herbivores has received increased attention in ecology. However, the mechanisms by which herbivores maintain N:P stoichiometric homeostasis are poorly understood. Here, using a field manipulation experiment we show that the grasshopper Oedaleus asiaticus maintains strong N:P stoichiometric homeostasis regardless of whether grasshoppers were reared at low or high density. Grasshoppers maintained homeostasis by increasing P excretion when eating plants with higher P contents. However, while grasshoppers also maintained constant body N contents, we found no changes in N excretion in response to changing plant N content over the range measured. These results suggest that O. asiaticus maintains P homeostasis primarily by changing P absorption and excretion rates, but that other mechanisms may be more important for regulating N homeostasis. Our findings improve our understanding of consumer-driven P recycling and may help in understanding the factors affecting plant-herbivore interactions and ecosystem processes in grasslands.
ContributorsZhang, Zijia (Author) / Elser, James (Author) / Cease, Arianne (Author) / Zhang, Ximei (Author) / Yu, Qiang (Author) / Han, Xingguo (Author) / Zhang, Guangming (Author) / College of Liberal Arts and Sciences (Contributor) / School of Life Sciences (Contributor) / Julie Ann Wrigley Global Institute of Sustainability (Contributor) / School of Sustainability (Contributor)
Created2014-08-04
Description
A large fraction of the world grasslands and savannas are undergoing a rapid shift from herbaceous to woody-plant dominance. This land-cover change is expected to lead to a loss in livestock production (LP), but the impacts of woody-plant encroachment on this crucial ecosystem service have not been assessed. We evaluate how tree cover (TC) has affected LP at large spatial scales in rangelands of contrasting social–economic characteristics in the United States and Argentina. Our models indicate that in areas of high productivity, a 1% increase in TC results in a reduction in LP ranging from 0.6 to 1.6 reproductive cows (Rc) per km[superscript 2]. Mean LP in the United States is 27 Rc per km[superscript 2], so a 1% increase in TC results in a 2.5% decrease in mean LP. This effect is large considering that woody-plant cover has been described as increasing at 0.5% to 2% per y. On the contrary, in areas of low productivity, increased TC had a positive effect on LP. Our results also show that ecological factors account for a larger fraction of LP variability in Argentinean than in US rangelands. Differences in the relative importance of ecological versus nonecological drivers of LP in Argentina and the United States suggest that the valuation of ecosystem services between these two rangelands might be different. Current management strategies in Argentina are likely designed to maximize LP for various reasons we are unable to explore in this effort, whereas land managers in the United States may be optimizing multiple ecosystem services, including conservation or recreation, alongside LP.
ContributorsAnadon, Jose Daniel (Author) / Sala, Osvaldo (Author) / Turner II, B. L. (Author) / Bennett, Elena M. (Author) / College of Liberal Arts and Sciences (Contributor) / School of Life Sciences (Contributor) / Julie Ann Wrigley Global Institute of Sustainability (Contributor) / School of Sustainability (Contributor) / School of Geographical Sciences and Urban Planning (Contributor)
Created2014-09-02
Description
We studied the microbial community structure of pilot two-stage membrane biofilm reactors (MBfRs) designed to reduce nitrate (NO[subscript 3]–) and perchlorate (ClO[subscript 4]–) in contaminated groundwater. The groundwater also contained oxygen (O[subscript 2]) and sulfate (SO[2 over 4]–), which became important electron sinks that affected the NO[subscript 3]– and ClO[subscript 4]– removal rates. Using pyrosequencing, we elucidated how important phylotypes of each “primary” microbial group, i.e., denitrifying bacteria (DB), perchlorate-reducing bacteria (PRB), and sulfate-reducing bacteria (SRB), responded to changes in electron-acceptor loading. UniFrac, principal coordinate analysis (PCoA), and diversity analyses documented that the microbial community of biofilms sampled when the MBfRs had a high acceptor loading were phylogenetically distant from and less diverse than the microbial community of biofilm samples with lower acceptor loadings. Diminished acceptor loading led to SO[2 over 4]– reduction in the lag MBfR, which allowed Desulfovibrionales (an SRB) and Thiothrichales (sulfur-oxidizers) to thrive through S cycling. As a result of this cooperative relationship, they competed effectively with DB/PRB phylotypes such as Xanthomonadales and Rhodobacterales. Thus, pyrosequencing illustrated that while DB, PRB, and SRB responded predictably to changes in acceptor loading, a decrease in total acceptor loading led to important shifts within the “primary” groups, the onset of other members (e.g., Thiothrichales), and overall greater diversity.
ContributorsOntiveros-Valencia, Aura (Author) / Tang, Youneng (Author) / Zhao, Heping (Author) / Friese, David (Author) / Overstreet, Ryan (Author) / Smith, Jennifer (Author) / Evans, Patrick (Author) / Rittmann, Bruce (Author) / Krajmalnik-Brown, Rosa (Author) / Biodesign Institute (Contributor) / Swette Center for Environmental Biotechnology (Contributor) / Julie Ann Wrigley Global Institute of Sustainability (Contributor) / School of Sustainability (Contributor)
Created2014-07-01
Description
Background: National and international strategies to increase physical activity emphasize environmental and policy changes that can have widespread and long-lasting impact. Evidence from multiple countries using comparable methods is required to strengthen the evidence base for such initiatives. Because some environment and policy changes could have generalizable effects and others may depend on each country's context, only international studies using comparable methods can identify the relevant differences. Methods: Currently 12 countries are participating in the International Physical Activity and the Environment Network (IPEN) study. The IPEN Adult study design involves recruiting adult participants from neighborhoods with wide variations in environmental walkability attributes and socioeconomic status (SES). Results: Eleven of twelve countries are providing accelerometer data and 11 are providing GIS data. Current projections indicate that 14,119 participants will provide survey data on built environments and physical activity and 7145 are likely to provide objective data on both the independent and dependent variables. Though studies are highly comparable, some adaptations are required based on the local context. Conclusions: This study was designed to inform evidence-based international and country-specific physical activity policies and interventions to help prevent obesity and other chronic diseases that are high in developed countries and growing rapidly in developing countries.
ContributorsKerr, Jacqueline (Author) / Sallis, James F. (Author) / Owen, Neville (Author) / De Bourdeaudhuij, Ilse (Author) / Cerin, Ester (Author) / Sugiyama, Takemi (Author) / Reis, Rodrigo (Author) / Sarmiento, Olga (Author) / Froemel, Karel (Author) / Mitas, Josef (Author) / Troelsen, Jens (Author) / Christiansen, Lars Breum (Author) / Macfarlane, Duncan (Author) / Salvo, Deborah (Author) / Schofield, Grant (Author) / Badland, Hannah (Author) / Guillen-Grima, Francisco (Author) / Aguinaga-Ontoso, Ines (Author) / Davey, Rachel (Author) / Bauman, Adrian (Author) / Saelens, Brian (Author) / Riddoch, Chris (Author) / Ainsworth, Barbara (Author) / Pratt, Michael (Author) / Schmidt, Tom (Author) / Frank, Lawrence (Author) / Adams, Marc (Author) / Conway, Terry (Author) / Cain, Kelli (Author) / Van Dyck, Delfien (Author) / Bracy, Nicole (Author) / College of Health Solutions (Contributor) / School of Nutrition and Health Promotion (Contributor)
Created2013
Description
With the development of technology, using photographs to measure plate waste is an increasing
trend. These photographs are later analyzed when the data is being entered into a form or
system. Previously, these forms or systems have not been assessed for usability. This research
study looks at three iterations of a digital plate waste observation system developed for the
School Lunch Study at Arizona State University. The System Usability Scale was used to
understand the functionality of the digital plate waste observation system. An area for free
responses was used to understand aspects of the system that were liked by research assistants
and what technical difficulties the research assistants encountered. These responses were used to
develop the next version of the digital plate waste observation system. Time to complete a task
was calculated to see the trends across all versions of the system. With each version, the System
Usability Scale scores increased along with the time to complete a task. This study found that
following the workflow of research assistants, being able to manipulate a photograph, having
menu items populated, and decreasing the amount of typing performed by adding selections to be
useful design aspects. Future digital plate waste observation systems can implement the
successful design aspects of this system, be aware of errors experienced, and implement helpful
features not found in this system. Future studies can look at the effect proctored training sessions
have on the time to complete a task and the relation of System Usability Scale scores with the
success of data entry.
trend. These photographs are later analyzed when the data is being entered into a form or
system. Previously, these forms or systems have not been assessed for usability. This research
study looks at three iterations of a digital plate waste observation system developed for the
School Lunch Study at Arizona State University. The System Usability Scale was used to
understand the functionality of the digital plate waste observation system. An area for free
responses was used to understand aspects of the system that were liked by research assistants
and what technical difficulties the research assistants encountered. These responses were used to
develop the next version of the digital plate waste observation system. Time to complete a task
was calculated to see the trends across all versions of the system. With each version, the System
Usability Scale scores increased along with the time to complete a task. This study found that
following the workflow of research assistants, being able to manipulate a photograph, having
menu items populated, and decreasing the amount of typing performed by adding selections to be
useful design aspects. Future digital plate waste observation systems can implement the
successful design aspects of this system, be aware of errors experienced, and implement helpful
features not found in this system. Future studies can look at the effect proctored training sessions
have on the time to complete a task and the relation of System Usability Scale scores with the
success of data entry.
ContributorsStott, Dahlia (Author) / Adams, Marc (Thesis director) / Barto, Henry (Committee member) / College of Health Solutions (Contributor) / Barrett, The Honors College (Contributor)
Created2019-12
Description
The objective of this study was to evaluate and compare the content of nutrition marketing materials within the cafeterias of schools in Central Arizona. By collecting photographs of marketing material from three elementary schools, one K-8 school, three middle schools and three high schools, 59 pieces of nutrition marketing were gathered. The schools chosen were a convenience sample and selected from schools that were already participating in ASU' s School Lunch Study. The photographs were sorted by grade level and then coded quantitatively and qualitatively for their purpose, visual components, strategies used and relevance. Results from this novel study provided insight into prevalence, size, textual content, educational content, strategies for fruit and vegetable marketing, messaging and overall design of existing nutrition marketing within the sample schools. This study found that the prevalence of nutrition marketing within all school cafeterias appeared to be low, particularly within elementary and middle schools. Diverse types of messaging were present among elementary, middle and high schools and a variety of appeals were utilized with little consistency. Many of the strategies used in the nutrition marketing appeared disconnected from the population it was intended to appeal to. Educational components were notably lacking within middle school cafeterias but were often effectively integrated into high school nutrition marketing. The results are unique to this population, and further research is required to evaluate the content of existing nutrition material on a larger scale, so efforts can be made to improve the persuasiveness of nutrition marketing in promoting fruit and vegetable consumption.
ContributorsXavier, Raevyn Francine (Author) / Bruening, Meg (Thesis director) / Adams, Marc (Committee member) / School of Nutrition and Health Promotion (Contributor) / Arizona State University. College of Nursing & Healthcare Innovation (Contributor) / Barrett, The Honors College (Contributor)
Created2018-12
Description
Background
African American women report insufficient physical activity and are disproportionally burdened by associated disease conditions; indicating the need for innovative approaches to promote physical activity in this underserved population. Social media platforms (i.e. Facebook) and text messaging represent potential mediums to promote physical activity. This paper reports the results of a randomized pilot trial evaluating a theory-based (Social Cognitive Theory) multi-component intervention using Facebook and text-messages to promote physical activity among African American women.
Methods
Participants (N = 29) were randomly assigned to receive one of two multi-component physical activity interventions over 8 weeks: a culturally-relevant, Social Cognitive Theory-based, intervention delivered by Facebook and text message (FI) (n = 14), or a non-culturally tailored print-based intervention (PI) (n = 15) consisting of promotion brochures mailed to their home. The primary outcome of physical activity was assessed by ActiGraph GT3X+ accelerometers. Secondary outcomes included self-reported physical activity, physical activity-related psychosocial variables, and participant satisfaction.
Results
All randomized participants (N = 29) completed the study. Accelerometer measured physical activity showed that FI participants decreased sedentary time (FI = −74 minutes/week vs. PI = +118 minute/week) and increased light intensity (FI = +95 minutes/week vs. PI = +59 minutes/week) and moderate-lifestyle intensity physical activity (FI = + 27 minutes/week vs. PI = −34 minutes/week) in comparison to PI participants (all P’s < .05). No between group differences for accelerometer measured moderate-to-vigorous intensity physical activity were observed (P > .05). Results of secondary outcomes showed that in comparison to the PI, FI participants self-reported greater increases in moderate-to-vigorous physical activity (FI = +62 minutes/week vs. PI = +6 minutes/week; P = .015) and had greater enhancements in self-regulation for physical activity (P < .001) and social support from family for physical activity (P = .044). Satisfaction with the FI was also high: 100% reported physical activity-related knowledge gains and 100% would recommend the program to a friend.
Conclusions
A culturally-relevant Facebook and text message delivered physical activity program was associated with several positive outcomes, including decreased sedentary behavior, increased light- and moderate-lifestyle intensity physical activity, enhanced psychosocial outcomes, and high participant satisfaction. Future studies with larger samples are warranted to further explore the efficacy of technology-based approaches to promote physical activity among African American women.
African American women report insufficient physical activity and are disproportionally burdened by associated disease conditions; indicating the need for innovative approaches to promote physical activity in this underserved population. Social media platforms (i.e. Facebook) and text messaging represent potential mediums to promote physical activity. This paper reports the results of a randomized pilot trial evaluating a theory-based (Social Cognitive Theory) multi-component intervention using Facebook and text-messages to promote physical activity among African American women.
Methods
Participants (N = 29) were randomly assigned to receive one of two multi-component physical activity interventions over 8 weeks: a culturally-relevant, Social Cognitive Theory-based, intervention delivered by Facebook and text message (FI) (n = 14), or a non-culturally tailored print-based intervention (PI) (n = 15) consisting of promotion brochures mailed to their home. The primary outcome of physical activity was assessed by ActiGraph GT3X+ accelerometers. Secondary outcomes included self-reported physical activity, physical activity-related psychosocial variables, and participant satisfaction.
Results
All randomized participants (N = 29) completed the study. Accelerometer measured physical activity showed that FI participants decreased sedentary time (FI = −74 minutes/week vs. PI = +118 minute/week) and increased light intensity (FI = +95 minutes/week vs. PI = +59 minutes/week) and moderate-lifestyle intensity physical activity (FI = + 27 minutes/week vs. PI = −34 minutes/week) in comparison to PI participants (all P’s < .05). No between group differences for accelerometer measured moderate-to-vigorous intensity physical activity were observed (P > .05). Results of secondary outcomes showed that in comparison to the PI, FI participants self-reported greater increases in moderate-to-vigorous physical activity (FI = +62 minutes/week vs. PI = +6 minutes/week; P = .015) and had greater enhancements in self-regulation for physical activity (P < .001) and social support from family for physical activity (P = .044). Satisfaction with the FI was also high: 100% reported physical activity-related knowledge gains and 100% would recommend the program to a friend.
Conclusions
A culturally-relevant Facebook and text message delivered physical activity program was associated with several positive outcomes, including decreased sedentary behavior, increased light- and moderate-lifestyle intensity physical activity, enhanced psychosocial outcomes, and high participant satisfaction. Future studies with larger samples are warranted to further explore the efficacy of technology-based approaches to promote physical activity among African American women.
ContributorsJoseph, Rodney (Author) / Keller, Colleen (Author) / Adams, Marc (Author) / Ainsworth, Barbara (Author) / College of Health Solutions (Contributor) / School of Nutrition and Health Promotion (Contributor) / Arizona State University. College of Nursing & Healthcare Innovation (Contributor)
Created2015-03-27