Long-Run Structural and Productivity Change in U.S. Agriculture: Effects of Prices and Policies

Long-Run Structural and Productivity Change in U.S. Agriculture: Effects of Prices and Policies by Wallace E. Huffman and Robert E. Evenson The paper presents (1) a conceptual framework for structural change when farms may be multiproduct or specialized and (2) an econometrics examination of causes of structural and total factor productivity (TFP) change for U.S. agriculture. Farm size, farm specialization, and part-time farming are the structural dimension emphasized, and they become potential channels to TFP change. Using state aggregate data starting in 1950, we conclude that input prices, public and private research, public extension, and government commodity programs have directly and indirectly caused change in U.S. farm structure and TFP. Our results suggest that changes in farm size, however, have been dominated by input price changes rather than by technology or government programs.farm structure, productivity, farm size, farm specialization, part-time farming, research, technical change, agriculture

Planning for Pedestrians and Bicyclists in North Carolina.

Over the past decade, as obesity has continued to rise among both youth and adults, interest has grown in developing policies to promote community environments that support healthy lifestyles.1 A broad range of local, regional, state, and federal policies under the rubrics of active living, smart growth, and sustainable development share the underlying assumption that they can help people make healthier choices. From a transportation planning perspective, the benefits of pedestrian and bicycle plans resulting from the building of infrastructure to support pedestrian and bicycle travel include improved health (for example, through increased levels of physical activity and reduced obesity), a better environment (for example, through lower carbon emissions), and a stronger economy (for example, through lower fuel bills). However, until more recently, the health benefits have not been specifically explored

Green Revolution Counterfactuals

In this paper, we conduct two "counterfactual" simulations for the 30-year period 1970-2000-the first holding 1970 crop genetic improvements (CGI) constant and the second presuming the International Agricultural Research Center (IARC) system had not been built. Both these counterfactuals apply to developing countries only. The core estimates on which the counterfactuals are based include country fixed effects , and the key estimates are for the Dietary Energy Sufficiency (DES) equation. DES affects birth rates, death rates, child mortality rates and malnutrition rates, making it possible to "endogenize" population growth in developing countries, in the counterfactuals. Reduced DES levels (from reduced CGI contributions) will lead to more births, more deaths and more child deaths and higher levels of malnutrition. The key technology variables that determine DES are the number of agricultural scientists per million hectares of cropland, the average years of schooling of adult males (over 25), and the level of Green Revolution Modern Varieties (GRMV) adoption. Our results show striking contrasts between the historical record and the alternative counterfactuals. The worst outcome is that without any Green Revolution Technologies or an IARC system to support it, which results in holding technological advancements constant at the 1970 level is a marginal improvement, leading to much higher prices over time, as agricultural production struggles to keep up with food demand in those countries. The endogenous feedback effects of population show the importance of nutrition and education, and argue strongly in favor of those factors playing a significant role in the improvement of human well-being that has been observed since the start of the Green Revolution to present.Research and Development/Tech Change/Emerging Technologies,

Glacial and Postglacial History of the White Cloud Peaks-Boulder Mountains, Idaho, U.S.A.

Glacial and glaciofluvial deposits are mapped and differentiated to develop new local, relative-age (RD) stratigraphies for the North Fork of the Big Lost River, Slate Creek and Pole Creek drainages in the White Cloud Peaks and Boulder Mountains, Idaho. This stratigraphic model expands the areal extent of the "Idaho glacial model". Volcanic ash samples collected from the study area are petrographically characterized and correlated, on the basis of mineralogy and glass geochemistry, to reference samples of identified Cascade Range tephras. Four distinct tephras are recognized including; Mount St. Helens-Set S (13,600-13,300 yr BP), Glacier Peak-Set B (11,250 yr BP), Mount Mazama (6600 yr BP) and Mount St. Helens-Set Ye (4350 yr BP). A core of lake sediments containing two tephra units was obtained from a site called "Pole Creek kettle". Pollen and sediment analyses indicate three intervals of late Pleistocene and Holocene climatic change. Cool and wet climatic conditions prevailed in the region shortly before and immediately following the deposition of the Glacier Peak-Set B ash (11,250 yr BP). Climatic warming occurred from approximately 10,500 to 6600 yr BP after which warm, dry conditions prevailed. Sediment accumulation in the kettle ceased by 4350 yr BP. The presence of Glacier Peak-Set B tephra in the base of the Pole Creek kettle core provides a minimum age of 11,250 yr BP for the retreat of valley glaciers from their Late Wisconsinan maximum position. A radiocarbon date of 8450 + 85 yr BP (SI-5181), and the presence of Mount Mazama ash (6600 yr BP) up-core support the Glacier Peak-Set B identification.La cartographie et l'identification des dépôts glaciaires et fluvioglaciaires a permis d'établir la stratigraphie locale des bassins du North Fork de la Big Lost River, du Pole Creek et du Slate Creek. Le modèle stratigraphique établi augmente la superficie déjà couverte par le modèle glaciaire de l'Idaho. Les échantillons de cendre volcanique prélevés ont été identifiés sur le plan pétrographique et mis en corrélation avec des tephras témoins provenant du Cascade Range, en se fondant sur la composition minérale et sur la géochimie du verre. On distingue quatre types de tephras: ceux de la série S du mont St. Helen's (13 600-13 300 BP), ceux de la série B du Glacier Peak (11 250 BP), ceux de la série S du mont St. Helen's (4350 BP) et ceux du mont Mazama (6600 BP). Une carotte de sédiments lacustres prélevée dans le kettle Pole Creek renferme deux tephras. L'analyse du pollen et des sédiments révèle l'existence de trois grands changements climatiques au Pleistocene supérieur et à l'Holocène: un climat frais et humide un peu avant et immédiatement après la mise en place des cendres de la série B du Glacier Peak (11 250 BP); une période de réchauffement (10 500-6600 BP); un climat chaud et sec. L'accumulation de sédiments dans le kettle prit fin vers 4350 BP. La présence du tephra de la série B du Glacier Peak à la base de la carotte donne la date minimale du retrait des glaciers de vallée (11 250 BP) à partir de leur emplacement au Wisconsinien supérieur. La date de 8450 + 85 ans BP et la présence, dans la partie supérieure de la carotte, de cendres provenant du mont Mazama (6600 BP) confirment l'identification de la série B du Glacier Peak.Idaho, U.S.A. Glaziale und glaziofluviale Ablagerungen wurden kartographiert und identifiziert, um eine neue, lokale, relative Alters-Stratigraphie der North Fork des Big Lost River, des Slate Creek und des Pole Creek in den White Cloud Peaks und Boulder Mountains, Idaho, zu en-twickeln. Proben vulkanischer Asche, die im untersuchten Gebiet gesammelt wurden, werden petrographisch bestimmt und auf der Basis von mineralogischer Zusammensetzung und Geochemie des Glases in Wechselbe-ziehung zu Referenz-Belegen von identifi-zierten Tephras von den Cascade Ranges gesetzt. Es werden vier verschiedene Tephras identifiziert: von der Série S des Mount St. Helens (13 600-13 300 v.u.Z.), von der Série B des Glacier Peak (11 250 v.u.Z.), von der Série Ye des Mount Mazama (6600 v.u.Z.) und des Mount St. Helens (4350 v.u.z.). Eine Probe von See-Sedimenten, der vom Pole Creek Kettle gewonnen wurde, enthâlt zwei Tephra-Einheiten. Die Pollen- und Sediment-Analysen lassen drei Intervalle klimatischen Wechsels im spâten Pleistozân und im Ho-lozan erkennen. Kalte und feuchte Klimatische Bedingungen herrschten in diesem Gebiet vor, kurz vor und unmittelbar nach der Ablagerung der Asche der Série B des Glacier Peak (11 250 v.u.Z.). Eine klimatische Erwàrmung trat zwischen ungefàhr 10 500 bis 6600 v.u.Z. auf, nach welcher warme, trockene Bedingungen vorherrschten. Die Sediment-An-hàufung in dem Kettel endete ungefàhr um 4350 v.u.Z. Das Vorkommen von Tephra der Série B des Glacier Peak in der Basis der Probe des Pole Creek Kettle ergibt ein Minimum-Alter von 11 250 v.u.Z. fur den Ruckzug der Gletscher des TaIs von ihrer maximalen Position im spâten Wisconsin. Ein Radiokar-bon-Datum von 8450 + 85 v.u.Z. (SI-5181) und das Vorkommen von Asche des Mount Mazama (6600 v.u.Z.) im oberen Teil der Probe stutzen die Identifizierung der Série B des Glacier Peak

Association Between Physical Activity and Proximity to Physical Activity Resources Among Low-Income, Midlife Women

INTRODUCTION: The association between levels of physical activity and perceived and objectively measured proximity to physical activity resources is unclear. Clarification is important so that future programs can intervene upon the measure with the greatest association. We examined correlations between perceived and objectively measured proximity to physical activity resources and then examined associations between both measures of proximity and objectively measured physical activity. METHODS: Participants (n = 199) were underinsured women from three counties in southeastern North Carolina. Perceived proximity to physical activity resources (e.g., parks, gyms, schools) was measured using surveys. Objectively measured proximity included geographic information systems road network distance to the closest resource and existence of resources within 1- and 2-mile buffers surrounding participants' homes. To examine the association between proximity to resources and activity, the dependent variable in multiple linear regression models was the natural logarithm of accelerometer-measured moderate to vigorous physical activity in minutes per day. RESULTS: Pearson correlation coefficients for perceptions of distance and objectively measured distance to physical activity resources ranged from 0.40 (gyms, schools) to 0.54 (parks). Perceived distance to gyms and objective number of schools within 1-mile buffers were negatively associated with activity. No statistically significant relationships were found between activity and perceived or objectively measured proximity to parks. CONCLUSION: Results indicate the need for both individual and environmental intervention strategies to increase levels of physical activity among underinsured, midlife women. More work is needed to determine the most effective strategies

Structural Basis for Isoform Selective Nitric Oxide Synthase Inhibition by Thiophene-2-Carboximidamides

The over production of nitric oxide in the brain by neuronal nitric oxide synthase (nNOS) is associated with a number of neurodegenerative diseases. Although inhibiting nNOS is an important therapeutic goal, it is important not to inhibit endothelial NOS (eNOS) owing to the critical role played by eNOS in maintaining vascular tone. While it has been possible to develop nNOS selective aminopyridine inhibitors, many of the most potent and selective inhibitors exhibit poor bioavailability properties. Our group and others have turned to more biocompatible thiophene-2-carboximidamides (T2C) inhibitors as potential nNOS selective inhibitors. We have used crystallography and computational methods to better understand how and why 2 commercially developed T2C inhibitors exhibit selectivity for human nNOS over human eNOS. As with many of the aminopyridine inhibitors, a critical active site Asp residue in nNOS vs Asn in eNOS is largely responsible for controlling selectivity. We also present thermodynamic integration results to better understand the change in pKa and thus charge of inhibitors once bound to the active site. In addition, relative free energy calculations underscore the importance of enhanced electrostatic stabilization of inhibitors bound to the nNOS active site compared to eNOS

Toward a descriptive model of galactic cosmic rays in the heliosphere

Researchers review the elements that enter into phenomenological models of the composition, energy spectra, and the spatial and temporal variations of galactic cosmic rays, including the so-called anomalous cosmic ray component. Starting from an existing model, designed to describe the behavior of cosmic rays in the near-Earth environment, researchers suggest possible updates and improvements to this model, and then propose a quantitative approach for extending such a model into other regions of the heliosphere

Beliefs about exercise and physical activity among pregnant women

The objective of this study was to document self-reported beliefs about physical activity and exercise among pregnant women

Sector Activities and Lessons Learned around Initial Implementation of the United States National Physical Activity Plan

National plans are increasingly common but infrequently evaluated. The 2010 United States National Physical Activity Plan (NPAP) provided strategies to increase population levels of physical activity. This paper describes (i) the initial accomplishments of the NPAP sector teams, and (ii) results from a process evaluation to determine how the sectors operated, their cross-sector collaboration, challenges encountered, and positive experiences