Effects of consuming a high carbohydrate diet after eight weeks of exposure to a ketogenic diet

<p>Abstract</p> <p>Background</p> <p>Ketogenic diets have been utilized for weight loss and improvement in metabolic parameters. The present experiments examined the effects of returning to a chow diet after prolonged ingestion of a ketogenic diet.</p> <p>Methods</p> <p>Rats were maintained on chow (CH) or a ketogenic diet (KD) for 8 weeks, after which the KD rats were given access to chow only (KD:CH) for 8 additional weeks. Caloric intake, body weight, and plasma leptin, insulin and ghrelin were measured before and after the dietary switch.</p> <p>Results</p> <p>After 8 weeks of consuming a ketogenic diet, KD rats had increased adiposity and plasma leptin levels, and reduced insulin, as compared to CH controls. One week after the diet switch, fat pad weight and leptin levels remained elevated, and were normalized to CH controls within 8 weeks of the dietary switch. Switching from KD to chow induced a transient hypophagia, such that KD:CH rats consumed significantly fewer calories during the first week after the dietary switch, as compared to calories consumed by CH rats. This hypophagia was despite significantly increased plasma ghrelin in KD:CH rats. Finally, KD:CH rats developed hyperphagia over time, and during weeks 6-8 after the diet switch consumed significantly more calories per day than did CH-fed controls and gained more weight than CH-fed controls.</p> <p>Conclusion</p> <p>Collectively, these data demonstrate that returning to a carbohydrate-based diet after a period of consuming a ketogenic diet has post-diet effects on caloric intake, body weight gain, and insulin levels.</p

The effects of human socioeconomic status and cultural characteristics on urban patterns of biodiversity

ABSTRACT. We present evidence that there can be substantial variation in species richness in residential areas differing in their socioeconomic and cultural characteristics. Many analyses of the impacts of urbanization on biodiversity rely on traditional &quot;urban-to-rural&quot; gradient measures, such as distance from urban center or population density, and thus can fail to account for the ways in which human socioeconomic and cultural characteristics are shaping the human-environment interaction and ecological outcomes. This influence of residential values and economic resources on biodiversity within the urban matrix has implications for human quality of life, for urban conservation strategies, and for urban planning

The value of agricultural water rights in agricultural properties in the path of development

This paper estimates the value of water rights in a rapidly urbanizing semi-arid area: Phoenix, Arizona. To do this we use hedonic pricing to explore the impact of water rights on property values in 151 agricultural land transactions that occurred between 2001 and 2005. We test two main hypotheses: (1) that the marginal willingness to pay for water rights is higher in more developed urbanizing areas than in less developed rural areas, and (2) that the marginal willingness to pay for water rights in urban areas is increasing in the value of developed land. We find that the marginal willingness to pay for water rights is highest among properties in urbanized or urbanizing areas where a significant proportion of the land has already been developed. Additionally, we find that the marginal willingness to pay for agricultural water rights is greatest in cities where developed land is most valuable

A Landscape Perspective on Climate-Driven Risks to Food Security: Exploring the Relationship between Climate and Social Transformation in the Prehispanic U.S. Southwest

Spatially and temporally unpredictable rainfall patterns presented food production challenges to small-scale agricultural communities, requiring multiple risk-mitigating strategies to increase food security. Although site-based investigations of the relationship between climate and agricultural production offer insights into how individual communities may have created long-term adaptations to manage risk, the inherent spatial variability of climate-driven risk makes a landscape-scale perspective valuable. In this article, we model risk by evaluating how the spatial structure of ancient climate conditions may have affected the reliability of three major strategies used to reduce risk: drawing upon social networks in time of need, hunting and gathering of wild resources, and storing surplus food. We then explore how climate-driven changes to this reliability may relate to archaeologically observed social transformations. We demonstrate the utility of this methodology by comparing the Salinas and Cibola regions in the prehispanic U.S. Southwest to understand the complex relationship among climate-driven threats to food security, risk-mitigation strategies, and social transformations. Our results suggest key differences in how communities buffered against risk in the Cibola and Salinas study regions, with the structure of precipitation influencing the range of strategies to which communities had access through time

Challenges in cybersecurity: Lessons from biological defense systems

Defending against novel, repeated, or unpredictable attacks, while avoiding attacks on the 'self', are the central problems of both mammalian immune systems and computer systems. Both systems have been studied in great detail, but with little exchange of information across the different disciplines. Here, we present a conceptual framework for structured comparisons across the fields of biological immunity and cybersecurity, by framing the context of defense, considering different (combinations of) defensive strategies, and evaluating defensive performance. Throughout this paper, we pose open questions for further exploration. We hope to spark the interdisciplinary discovery of general principles of optimal defense, which can be understood and applied in biological immunity, cybersecurity, and other defensive realms

Resilience of Past Landscapes: Resilience Theory, Society, and the Longue Durée

Resilience theory is an expanding body of ideas that attempts to provide explanations for the source and role of change in adaptive systems, particularly the kinds of change that are transforming. Scholars from various disciplines have contributed to the current state of this formulation. This article proposes that resilience theory would benefit from an increasing collaboration with archaeologists, who would provide a long-term perspective on adaptive cycles. Although archaeologists and anthropologists have written provocatively about studying the resilience of past and present societies, such an approach has not become common in these disciplines. We suggest, however, that a resilience framework offers a potential mechanism for reinvigorating the conceptual base of archaeological and anthropological disciplines. To make this case, we (1) highlight three features of resilience theory, including cross-scale interactions, information flow, and phases of the adaptive cycle; (2) examine the extent to which purely natural or social science analyses would give complementary or contradictory conclusions; and (3) discuss the implications of using a long-term integrative perspective for understanding linked social and ecological systems

Legacies of Agriculture and Urbanization in Labile and Stable Organic Carbon and Nitrogen in Sonoran Desert Soils

Soils regulate air and water quality by storing large pools of carbon (C) and nitrogen (N). Land management decisions have an enduring influence on the integrity and size of these pools, particularly in the upper soil layers. An important challenge, therefore, is to identify how soil C and N bear the marks of both past and present land use. Several studies have documented that effects of agriculture on soil properties can persist long after agricultural abandonment, but these studies typically examine sites returning to forest or grassland. Fewer have investigated legacies of agricultural land use when formerly agrarian land becomes urban. Urban soil management may be intensive, characterized by modifications in microtopography, vegetation, and nutrient and water inputs. We thus hypothesized that urban residential land use would negate any agrarian signatures in the pool sizes of labile (readily mineralized) soil organic C and N, but that agrarian legacies would persist in pools of stable (not readily mineralized) C and N. We tested this hypothesis in arid central Arizona (USA), where residential development in the Phoenix metropolis occurred on both agrarian and uncultivated desert lands throughout the 20th Century. We used a year-long incubation to quantify labile and stable organic C and N in soils (to 15.2 cm depth) from desert land, contemporary agrarian land, residential yards that were converted from desert, and yards converted from agrarian land use. Labile N in residential soils may have been independent of historical provenance, consistent with the hypothesis that readily-mineralized pools converge on a single signature of current (residential) land use. Labile C, stable C, and stable N showed the influence of agrarian history decades after conversion to urban residential use. These agrarian legacies in currently residential soil result from the persistence of past agrarian amendments to soil, and are not artifacts of the preferential cultivation of inherently fertile land. Current residential soil management is further amending soil C and N pools on top of the legacy pools left behind by agriculture. We calculate that the persisting influence of agrarian history on soils is similar in magnitude to contemporary urban residential effects

Fifteen Weddings and a Funeral: Case Studies and Resilience-based Management

"Resilience theory" is a systematic methodology for understanding the dynamics of coupled social-ecological systems (SESs). Its ongoing development requires that resilience theory be confronted with case studies to assess its capacity to help understand and develop policy for SESs. This paper synthesizes the findings from several papers in the special feature "Exploring Resilience in Social-Ecological Systems" that do just this. It then highlights key challenges facing resilience as a theory for understanding SESs and provides some avenues for future research