Thomas Park - US grants

This dissertation study focuses on the character of production strategies in 10th to 14th Century Iceland in the context of foreign exchange, ecological succession and climatic change. Field ethnography and other Icelandic research on agriculture will be used to carry out a problem-oriented analysis of Medieval documents on livestock production. This research will provide a valuable critical analysis of historical data relating to the effects of climate change and socioeconomic transformations over time.

LBP:\A9321194 Park This project supports the dissertation research of an anthropology student from the University of Arizona, studying the impact of ethnicity and state intervention on small-scale, intensive irrigated agriculture in Morocco. Using a combination of archival and ethnographic research, the student will study two villages, one with a sure source of irrigation water from a water control project, and one with the traditional insecure sources of water. The student will interview members of the three dominant ethnic groups in these villages to investigate how social class, ethnicity, and access to development programs interact to affect the productivity of small-holder farming. This research is important because traditional farmers in many parts of the world are involved with state irrigation programs. Increased understanding of local cases such as this one, of how ethnic differences and social-economic class position within the village affect the farmers' ability to take advantage of state- sponsored programs, and whether these programs actually increase productivity, will provide valuable information to economic development planners. ***

DESCRIPTION: The conceptual issue addressed in this proposal is how neurons in the lateral superior olive (LSO) obtain their selectivity for interaural intensity disparities (IIDs), and whether neurons with different IID selectivities are arranged in an orderly fashion within isofrequency contours of the LSO. The impetus for this proposal derives from the success that investigators have had in discovering how medial superior olivary (MSO) neurons, and their avian analogue in the nucleus laminaris, obtain their selectivity for a particular interaural time disparity and how those features are systematically represented with those nuclei. In contrast, the way in which LSO cells obtain their individual sensitivity for a particular IID and the degree to which an orderly arrangement of IID sensitivities might exist in the LSO are issues that have received little attention and are poorly understood. Only Reed and Blum have proposed a hypothesis that addresses both the issue of how LSO cells obtain their individual IID selectivity and what structural features could also impart an orderly arrangement of IID selectivity within isofrequency contours. Their hypothesis, however, has never been tested experimentally. Moreover, it relies only on the differences in thresholds of the inputs from the two ears, and thus it does not incorporate a number of other important features of the LSO, such as latency and time-intensity trading. The aims of this proposal are to test the Reed and Blum hypothesis and fill in the gaps in our knowledge about how LSO neurons obtain their particular IID selectivity. The first series of experiments has two goals: 1) To survey the LSO and obtain an overall view of the prevalence of neurons whose IID selectivities are predicted by threshold differences between the excitatory and inhibitory ears. 2) To distinguish between the hypothesis based on threshold differences, and alternative hypotheses which predict that IID selectivity is determined by differences in the relative strengths of the excitatory and inhibitory inputs, differences in arrival times from the two ears, or by some combination of threshold, strength and latency differences. These hypotheses will be evaluated by obtaining indices of input thresholds, strengths and latencies for each ear and then confirming their relative contributions for creating the neuron s IID selectivity through time-intensity trading experiments. A second series of experiments will reveal the degree to which IID selectivities are arranged in an orderly fashion within one isofrequency contour in the LSO. These experiments will exploit the greatly hypertrophied 60 kHz isofrequency contour of the mustache bat s LSO, yielding data from a large number of cells within one isofrequency contour.

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The researchers would use remote-sensing images from 1982-98 to document urban change in six African cities and contrast what happens in urban areas with development in urban hinterlands. In work weighted toward the poorer sections of the cities, households would be interviewed to learn about livelihood strategy histories, relationships to natural resource use, and impacts of changes in urban structure.The results would be used to assess the effects of various projects and to initiate hypotheses that could be tested in later studies. A preliminary hypothesis is that the process of urbanization in arid Africa has produced a new poor, people whose lives are shaped more by collective use of aid than by individual maximizing behavior. If this is true, the information can be used in urban planning as well as in furthering the understanding of African urbanization.

Coupled natural and human systems may be viewed mathematically as dynamical systems (systems of differential or difference equations) in which humans are involved either as parts of the system or by influencing some processes, whether intentionally or not. Alternatively they may be considered as complex systems -- collections of agents engaged in rule-governed behavior. In either case, robustness refers to the stability and resistance to perturbation of such dynamical or complex systems as they evolve in state space. A dynamical system is said to be structurally stable if reasonably small perturbations to the system result in a new dynamical system with the same qualitative dynamics. The concept of robustness raises questions that lie outside the purview of stability theory, such as the interplay of system organization and system dynamics. Processes like adaptation and positive feedback can increase the robustness of living systems and coupled natural and human systems, but the linkage between efficiency and robustness may be an inverse one in which optimal efficiency is at the expense of robustness in the face of changing environmental conditions. In some cases, robustness may be an emergent property of evolved systems, or it may be possible to engineer systems to enhance their robustness. To address these issues, this award will sponsor a conference to be held at the Santa Fe Institute in the Spring of 2003. The conference will bring together scientists from a range of disciplines, including physics, mathematics, computer science, earth and climate science, ecology, anthropology and archaeology, to discuss theoretical research and case studies, with emphasis being placed on comparative discussion of the case studies. Papers will be circulated in advance and presented in a single forum attended by all conference participants. Results of the conference are expected to be published

The robustness of coupled natural and human systems has become a matter of increasing concern as the modern industrial system's impact on the natural systems of the planet becomes more and more apparent and issues of sustainability become paramount. This conference will contribute to explorations of robustness in coupled natural and human systems at scales ranging from planetary (climate) and macroscales through the mesoscale of sociocultural systems to the microscopic scale of disease microevolution. Participants will explore the association of different spatial scale with varying temporal scales, and they will help answer a number of critical questions, including whether robustness is best assessed by analysis of existing data or through simulation modeling, how engineered systems compare to complex adaptive systems in terms of robustness and/or a calculus of costs and benefits, and under what circumstances robust systems are most likely to develop. Through this conference, participants and other scholars will develop new insights into and new approaches for investigating robustness in coupled natural and human systems. Broader impacts of this project include the expansion of an interdisciplinary network of scientists to explore this important topic in a collaborative framework. The results of their discussions and subsequent collaborative activities could ultimately yield many practical benefits for land and resource managers as well as others who have responsibilities associated with maintaining environmental quality. This project is supported by an award resulting from the FY 2002 special competition in Biocomplexity in the Environment focusing on the Dynamics of Coupled Natural and Human Systems.

Beginning in the late 1960s, the West African Sahel zone repeatedly made headlines because of a number of environmental and economic problems that manifest themselves in changes in land cover. While these changes often were referred to as "desertification," scientists did not develop consensus regarding the exact meaning of this notion, the mechanisms governing it, and the extent of the problem in the Sahel. Recent remote sensing-based studies have shown an overall greening trend in parts of the Sahel, which might indicate that positive developments have been going on. The meaning of "greening" is as vague as that of "desertification," however, and its implications on the ground are far from clear and unambiguous. This research project will develop empirical evidence that will inform basic understanding of the interactions among land use, land cover, and people's livelihoods in the face of variable and unpredictable rainfall in contrasting study sites in two Sahelian countries, Mauritania and Senegal. The investigators will adopt a cross-disciplinary perspective and borrow methods from the natural and social sciences in order to approach this complex research problem. They will use remote sensing techniques to measure and map current and past land-cover changes, relate them to rainfall data, conduct a variety of focus group discussions to reconstruct current and past land-use and management practices, georeference different land-use units in the study sites, and investigate how decision making on land use and management by different resource user groups takes into account environmental constraints and opportunities. They also will assess how land use and management affects land cover measured by remote sensing. Defining a range of resource user groups and teasing out and quantifying linkages between them and their biophysical environment will lay the ground work for future integration of land-use decision making with spatially explicit models of environmental change.

This project will help enhance basic understanding of human and natural systems in dryland environments, particularly the relative contributions of human behavior and climate variability to land- use and land-cover change. The project results may help break the gridlock in the desertification debate by deepening understanding of the driving forces influencing desertification and greening. Moreover, identifying economically viable and environmentally sustainable land-use strategies under climate variability might be used to help communities and aid agencies to make more informed resource management decisions.

The objective of this project is to investigate adaptations in the peripheral and central nervous systems of the naked mole-rat. Naked mole-rats have an unusual lifestyle in that they combine a fully subterranean existence with extreme sociality, and a proclivity for living in large numbers. Thus, in their crowded burrows where many animals share a limited air supply, these animals are exposed to the challenges of breathing exceptionally high levels of carbon dioxide and exceptionally low levels of oxygen. Initial studies have revealed that, behaviorally, naked mole-rats are extremely resistant to high carbon dioxide and low oxygen. The goals of the project now are to better understand the underlying mechanisms that make this resistance possible. The project uses a variety of methods including behavioral, electrophysiological, anatomical, and molecular techniques with an emphasis on moving freely between experiments that focus on neural mechanisms and those that focus on natural behaviors. The project also relies heavily on comparative data from closely and distantly related species that have evolved under different carbon dioxide and oxygen conditions. The expected impacts of this project include contributing to the understanding of the nervous system in general, and to adaptations to environmental challenges in particular. Also, the project will develop a new model system for studying the evolution of the nervous system and behavior. The project will provide training opportunities in systems neuroscience for both graduate and undergraduate students. The project will also enhance laboratory courses in that several laboratory exercises have been developed with these animals.

This project will contribute to understanding tolerance of hypoxia (low oxygen levels) within the nervous system by studying the African naked mole-rat. This mammal lives in crowded, oxygen-starved burrows, and has evolved the ability to survive extended periods of oxygen deprivation without triggering brain cell death. This project will test new target genes that may protect brain cells from cell death resulting from exposure to hypoxia, with potential applications in designing new treatments for humans that experience oxygen deprivation during traumatic events like a stroke or heart attack. By studying the genome of the naked mole-rat, the investigators previously discovered changes in the genes of this species that likely reduce cell death from oxygen deprivation. The goal of the current project is to test each of those genes for its potential role in brain cell protection. The project will support two graduate students each year, who will help mentor a number of undergraduate student researchers recruited from existing programs targeting students from groups underrepresented in science. Information on the naked mole-rat will be shared via outreach to a local zoo and area high schools. <br/><br/>This project will investigate molecular, cellular, and physiological mechanisms in the brain that underly hypoxia tolerance and will contribute to understanding evolutionary adaptations to environmental challenges in general. The naked mole-rat will be developed as a model system for studying the molecular and genetic basis of hypoxia tolerance in the mammalian brain. Brain cells from the naked mole-rat display an intrinsic tolerance to hypoxia and a dramatic reduction in calcium accumulation during hypoxia compared with most other mammals, which is hypothesized to result from multiple adaptations that limit and buffer calcium currents. Additionally, there appears to be a significant neuroprotective role for the endocannabinoid system in the brain of the naked mole-rat. This project will specifically examine the neuroprotective function of the calcium channel TRPM7, NMDA glutamate-receptor ion channels, a calcium-related kinase, and the calcium-binding protein parvalbumin, as well as the endocannabinoid system. The investigators will use brain slice electrophysiology, mass spectrometry, and gene manipulation techniques to determine the molecular and genetic basis of hypoxia tolerance in the naked mole-rat. Experiments designed to introduce naked mole-rat-specific gene alterations into mouse cells will test the hypothesis that the changes in the naked mole-rat genes can also protect other species. Understanding how brain cells are protected from oxygen deprivation may ultimately lead to new therapeutic targets for heart attack and stroke victims. Several graduate and undergraduate student trainees will participate in the research, and results will be incorporated into undergraduate courses and outreach activities.<br/><br/>This award was co-funded by the Physiological Mechanisms and Biomechanics Program and the Neural Systems Cluster Organization Program in BIO-IOS.<br/><br/>This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.