Land Quality and International Agricultural Productivity: A Distance Function Approach

Agricultural productivity measurement has been of great interest in recent years. Although analysts have long recognized that land quality plays an important role in agricultural productivity, land quality has been difficult to quantify and include in productivity models due to d ata limitations. Poor land quality, in the form of desertification, erosion, and poor soil quality, as well as climate and precipitation may limit growth in productivity over time. A Malmquist productivity index is proposed that decomposes productivity into efficiency change, technical change and land quality components and accounts for inter-country differences in land quality. The index is then applied to a 109-country data set covering 1980 to 2003. Many countries with lower productivity growth are limited by their resource endowment, and thus require policies and technology that reflect the needs of those environments.Land Economics/Use, Productivity Analysis,

RESOURCE QUALITY AND AGRICULTURAL PRODUCTIVITY: A MULTI-COUNTRY COMPARISON

This paper builds on earlier studies of agricultural productivity by incorporating spatially referenced soil and climate data combined with high-resolution land-cover data. Econometric analysis of these data, along with panel data on agricultural inputs and outputs from 110 countries for 1961-1997, quantifies the significant impact that differences in land quality have on agricultural productivity.Productivity Analysis,

The Effects of Slots and Flaps on Lateral Control of a Low-wing Monoplane as Determined in Flight

This paper presents the results of flight tests made to determine the effect of slots and flaps on the lateral control of a low-wing monoplane. Maximum angular accelerations in roll and yaw produced by sudden application of the ailerons and maximum accelerations in yaw produced by sudden application of the rudder during gliding flight were recorded for the following wing arrangements: (a) no auxiliary device; (b) full-span slots; (c) plain flaps; (d) flaps and full-span slots; (e) wing-tip slots. Rolling- and yawing-moment coefficients were derived from the accelerations. The full span slots and the flaps each had about the same influence on the aileron rolling moments. At values of the lift coefficient obtainable with the plain wing, the effect of these devices was negligible. At the higher lift coefficients obtainable with these devices, the rolling-moment coefficients increased slightly but, despite this increase, the aileron effectiveness progressively decreased with increasing lift coefficient, owing to the corresponding reduction in air speed. In the range covered by the tests, the effectiveness of the controls was appreciably reduced by the wing-tip slots. The adverse yawing moment of the ailerons experienced at the large lift coefficients obtained with the flaps was appreciably less than at similar lift coefficients obtained with either full-span or wing-tip slots. The yawing moments produced by the rudder were only slightly affected by the use of the auxiliary devices. The airplane was found to be laterally unstable with all combinations tested. Because of the angular velocities acquired in the time taken to deflect the ailerons the rolling moments recorded in flight were only about two thirds the values that would have been obtained with the wing restrained as in wind-tunnel tests

The Role of Social Movements in the Macro Political System

One of the central concepts in the study of social movements is that of the “Protest Cycle” (e.g., Tarrow 1998). The imagery of the Cycle is that of heightened protests, across issue areas and groups. Scholars have connected its rise to openings in the Political Opportunity Structure, which signals to early risers that the time may be ripe for collective action (e.g., Tarrow 1998). We find it striking that this core idea in the social movements literature has not been connected more explicitly to the literature on public opinion. This is especially striking because social movement scholars have begun to explicitly address the role of public opinion in their models (e.g., Soule and Olzak 2004; Soule and King 2006). Suppose that ideological social movements, taken as a whole, rise and fall across time in a predictable fashion. Perhaps the effects of these movements on public opinion and policy are also predictable, as some have argued (e.g., Burstein and Linton 2002). In that case, social movements play a vital role in connecting public opinion to policy. How can this be the case? Public opinion can be summarized as policy mood (e.g. Erikson, MacKuen and Stimson 2002). It turns out that at the national level, people’s preferences regarding the degree to which they think government should be more or less active moves over time in liberal and conservative directions. Policy mood causes national election outcomes, which in turn causes how liberal or conservative the legislation is that Congress passes. Policy mood should matter for social movements, as well . Dynamic policy mood presents social movement organizers with opportunities; when policy mood is liberal, liberal social movements have more of an opportunity to be successful because the issues they care about will receive more support from the American people (Soule and Olzak 2004). Liberal social movements will then rise, leading to greater policy success (the opposite will be true for conservative social movements). However, the activism of these rising social movements leads to an ideological backlash, which in turn moves public mood in the opposite direction in an effort to find balance. We test our hypotheses using a data set of public protest events that records protest events for each day from 1960 to 1995 ( see a data source summary in Soule and Davenport 2009 ). The evidence supports our hypotheses, indicating that social movements play an important role in the macro political system

A record of eruption and intrusion at a fast spreading ridge axis : axial summit trough of the East Pacific Rise at 9–10°N

Author Posting. © American Geophysical Union, 2009. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geochemistry Geophysics Geosystems 10 (2009): Q10T07, doi:10.1029/2008GC002354.High-resolution side-scan sonar, near-bottom multibeam bathymetry, and deep-sea photo and bathymetry traverses are used to map the axial summit trough (AST) at the East Pacific Rise between 9 and 10°N. We define three ridge axis morphologic types: no AST, narrow AST, and wide AST, which characterize distinct ridge crest domains spanning tens of kilometers along strike. Near-bottom observations, modeling of deformation above intruding dikes, and comparisons to the geologic and geophysical structure of the ridge crest are used to develop a revised model of AST genesis and evolution. This model helps constrain the record of intrusive and extrusive magmatism and styles of lava deposition along the ridge crest at time scales from hundreds to tens of thousands of years. The grabens in the narrow-AST domain (9°43′–53′N) are consistent with deformation above the most recent (<10) diking events beneath the ridge crest. Frequent high–effusion rate extrusive volcanism in this domain (several eruptions every ∼100 years) overprints near-axis deformation and maintains a consistent AST width. The most recent eruption at the ridge crest occurred in this area and did not significantly modify the physical characteristics of the AST. The grabens in the wide-AST domain (9°23′–43′N) originated with similar dimensions to the narrow AST. Spreading, driven primarily by the intrusion of shallow dikes within a narrow axial zone, causes the initial graben bounding faults to migrate away from the axis. Infrequent extrusive volcanism (several eruptions every ∼1000 years) fills a portion of the subsidence that accumulates over time but does not significantly modify the width of the AST. Outside of these domains, lower–effusion rate constructional volcanism without efficient drain-back fills and erases the signature of the AST. The relative frequency of intrusive versus extrusive magmatic events controls the morphology of the ridge crest and appears to remain constant over millennial time scales within the domains we have identified; however, over longer time scales (∼10–25 ka), domain-specific intrusive-to-extrusive ratios do not appear to be fixed in space, resulting in a fairly consistent volcanic accretion over the length scale of the second-order ridge segment between 9°N and 10°N.This work was supported by NSF grants OCE-0525863 to D. Fornari and S. A. Soule; OCE-0732366 to S. A. Soule; and OCE-9819261 to H. Schouten, M. Tivey, and D. Fornari and by CNRS to J. Escartın

When Process Affects Punishment: Differences in Sentences After Guilty Plea, Bench Trial, and Jury Trial in Five Guidelines States

The research reported in this Essay examines process discounts-differences in sentences imposed for the same offense, depending upon whether the conviction was by jury trial, bench trial, or guilty plea-in five states that use judicial sentencing guidelines. Few guidelines systems expressly recognize plea agreement as an acceptable basis for departure, and none authorizes judges to vary sentences based upon whether or not the defendant waived his right to a jury trial and opted for a bench trial. Nevertheless, we predicted that because of the cost savings resulting from waivers, judges and prosecutors in any sentencing system would ensure that guilty plea convictions would generate the lowest sentences, with bench trial sentences averaging higher than plea-based sentences for the same offense, and sentences following jury trials averagingt he highest of all, even after controllingf or otherf actors associated with sentence severity. We found that a significant plea discount is evident for most offenses in all five states. Waiving a jury in favor of a bench trial has less consistent punishment consequences. Among states and even within a single state, the prevalence of process discounts is extraordinarily varied, as are the causes and methods of discounting. The Essay explores how these findings might inform sentencing reform and discusses the use of bench trials in sentencing guidelines systems generally

Formation of submarine lava channel textures : insights from laboratory simulations

Author Posting. © American Geophysical Union, 2006. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research 111 (2006): B03104, doi:10.1029/2005JB003796.Laboratory simulations using polyethylene glycol (PEG) extruded at a constant rate and temperature into a tank with a uniform basal slope and filled with a cold sucrose solution generate channels that are defined by stationary levees and mobile flow interiors. These laboratory channels consistently display the following surface textures in the channel: smooth, folded, lineated, and chaotic. In the simulations, we can observe specific local conditions including flow rate, position within the channel, and time that combine to develop each texture. The textures in PEG flows form due to relative differences in shear forces between the PEG crust and the underlying liquid wax. Minimal shear forces form smooth crust, whereas folded crust forms when the shear is sufficiently high to cause ductile deformation. Brittle deformation of solid PEG creates a chaotic texture, and lineated crust results from shear forces along the channel-levee margin. We observe similar textures in submarine lava channels with sources at or near the Axial Summit Trough of the East Pacific Rise between 9° and 10°N. We mapped the surface textures of nine submarine lava channels using high-resolution digital images collected during camera tows. These textural maps, along with observations of the formation of similar features in analog flows, reveal important information about the mechanisms occurring across the channel during emplacement, including relative flow velocity and shear stress.The cruise was funded by a grant to WHOI from the National Science Foundation (NSF) OCE-9819261, with additional funding provided by WHOI thorough the Vetlesen Foundation. The PEG experiments were funded by NSF OCE-0425073 in a grant to Tracy Gregg

The Initial Step in Human Immunodeficiency Virus Type 1 GagProPol Processing Can Be Regulated by Reversible Oxidation

BACKGROUND: Maturation of human immunodeficiency virus type 1 (HIV-1) occurs upon activation of HIV-1 protease embedded within GagProPol precursors and cleavage of Gag and GagProPol polyproteins. Although reversible oxidation can regulate mature protease activity as well as retrovirus maturation, it is possible that the effects of oxidation on viral maturation are mediated in whole, or part, through effects on the initial intramolecular cleavage event of GagProPol. In order assess the effect of reversible oxidation on this event, we developed a system to isolate the first step in protease activation involving GagProPol. METHODOLOGY/PRINCIPAL FINDINGS: To determine if oxidation influences this step, we created a GagProPol plasmid construct (pGPfs-1C) that encoded mutations at all cleavage sites except p2/NC, the initial cleavage site in GagProPol. pGPfs-1C was used in an in vitro translation assay to observe the behavior of this initial step without interference from subsequent processing events. Diamide, a sulfhydral oxidizing agent, inhibited processing at p2/NC by >60% for pGPfs-1C and was readily reversed with the reductant, dithiothreitol. The ability to regulate processing by reversible oxidation was lost when the cysteines of the embedded protease were mutated to alanine. Unlike mature protease, which requires only oxidation of cys95 for inhibition, both cysteines of the embedded protease contributed to this inhibition. CONCLUSIONS/SIGNIFICANCE: We developed a system that can be used to study the first step in the cascade of HIV-1 GagProPol processing and show that reversible oxidation of cysteines of HIV-1 protease embedded in GagProPol can block this initial GagProPol autoprocessing. This type of regulation may be broadly applied to the majority of retroviruses

The final stages of slip and volcanism on an oceanic detachment fault at 13°48′N, Mid‐Atlantic Ridge

Author Posting. © American Geophysical Union, 2018. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geochemistry, Geophysics, Geosystems 19 (2018): 3115-3127, doi:10.1029/2018GC007536.While processes associated with initiation and maintenance of oceanic detachment faults are becoming better constrained, much less is known about the tectonic and magmatic conditions that lead to fault abandonment. Here we present results from near‐bottom investigations using the submersible Alvin and autonomous underwater vehicle Sentry at a recently extinct detachment fault near 13°48′N, Mid‐Atlantic Ridge, that allow documentation of the final stages of fault activity and magmatism. Seafloor imagery, sampling, and near‐bottom magnetic data show that the detachment footwall is intersected by an ~850 m‐wide volcanic outcrop including pillow lavas. Saturation pressures in these vesicular basalts, based on dissolved H2O and CO2, are less than their collection pressures, which could be explained by eruption at a shallower level than their present depth. Sub‐bottom profiles reveal that sediment thickness, a loose proxy for seafloor age, is ~2 m greater on top of the volcanic terrain than on the footwall adjacent to the hanging‐wall cutoff. This difference could be explained by current‐driven erosion in the axial valley or by continued slip after volcanic emplacement, on either a newly formed or pre‐existing fault. Since current speeds near the footwall are unlikely to be sufficient to cause significant erosion, we favor the hypothesis that detachment slip continued after the episode of magmatism, consistent with growing evidence that oceanic detachments can continue to slip despite hosting magmatic intrusions.National Science Foundation (NSF) Grant Numbers: OCE‐1259218, OCE‐1260578, OCE‐17365472019-03-1