U.S. agriculture : another solid year in 1998?

U.S. agriculture had a very good year in 1997, with profits widely shared among the nation's farmers. While few producers could boast of bell-ringer profits, as they did in 1996, nearly all could claim a good year. The year was especially welcome to the nation's cattle producers, who had struggled through an extended period of losses. The cattle industry rebounded much faster and further than anyone expected. While Mother Nature did bring major flooding to the Northern Plains states in late spring, most parts of the nation had good growing conditions in 1997. The result was an abundant harvest of the major crops and a moderate slide in crop prices. All in all, farm income was strong, but not as strong as the year before, and agriculture's balance sheet was bolstered further by gains in farmland values.> Drabenstott and Lamb review the year just passed for U.S. agriculture and suggest the year ahead will be another solid one, although income will probably slip from 1997 levels. After a big harvest last year, U.S. grain bins are fuller than they have been in three years. Moreover, the turmoil in Asian financial markets is likely to trim export demand for U.S. food and agricultural products in the year ahead. Profits in the livestock industry should continue, but fall somewhat from last year's level. Pork prices, in particular, may be under some downward pressure due to a buildup in pork supplies and a tailing off in export demand. One major wild card in the 1998 outlook is El Nino. While current forecasts suggest little impact on 1998 crop production, much depends on when and how quickly El Nino weather conditions fade. World grain stocks are still small enough that any crop shortfall could send prices sharply higher. Barring a major weather disruption, however, U.S. agriculture appears headed toward a solid year in 1998.Agriculture ; Farm income ; Agricultural prices

Stationkeeping for the Lunar Reconnaissance Orbiter (LRO)

The Lunar Reconnaissance Orbiter (LRO) is scheduled to launch in 2008 as the first mission under NASA's Vision for Space Exploration. Follo wing several weeks in a quasi-frozen commissioning orbit, LRO will fl y in a 50 km mean altitude lunar polar orbit. During the one year mis sion duration, the orbital dynamics of a low lunar orbit force LRO to perform periodic sets of stationkeeping maneuvers. This paper explor es the characteristics of low lunar orbits and explains how the LRO s tationkeeping plan is designed to accommodate the dynamics in such an orbit. The stationkeeping algorithm used for LRO must meet five miss ion constraints. These five constraints are to maintain ground statio n contact during maneuvers, to control the altitude variation of the orbit, to distribute periselene equally between northern and southern hemispheres, to match eccentricity at the beginning and the end of the sidereal period, and to minimize stationkeeping (Delta)V. This pape r addresses how the maneuver plan for LRO is designed to meet all of the above constraints

Rapid formation of a modern bedrock canyon by a single flood event

Deep river canyons are thought to form slowly over geological time (see, for example, ref. 1), cut by moderate flows that reoccur every few years. In contrast, some of the most spectacular canyons on Earth and Mars were probably carved rapidly during ancient megaflood events. Quantification of the flood discharge, duration and erosion mechanics that operated during such events is hampered because we lack modern analogues. Canyon Lake Gorge, Texas, was carved in 2002 during a single catastrophic flood. The event offers a rare opportunity to analyse canyon formation and test palaeo-hydraulic-reconstruction techniques under known topographic and hydraulic conditions. Here we use digital topographic models and visible/near-infrared aerial images from before and after the flood, discharge measured during the event, field measurements and sediment-transport modelling to show that the flood moved metre-sized boulders, excavated ~7 m of limestone and transformed a soil-mantled valley into a bedrock canyon in just ~3 days. We find that canyon morphology is strongly dependent on rock type: plucking of limestone blocks produced waterfalls, inner channels and bedrock strath terraces, whereas abrasion of cemented alluvium sculpted walls, plunge pools and streamlined islands. Canyon formation was so rapid that erosion might have been limited by the ability of the flow to transport sediment. We suggest that our results might improve hydraulic reconstructions of similar megafloods on Earth and Mars

Growth and form of the mound in Gale Crater, Mars: Slope wind enhanced erosion and transport

Ancient sediments provide archives of climate and habitability on Mars. Gale Crater, the landing site for the Mars Science Laboratory (MSL), hosts a 5-km-high sedimentary mound (Mount Sharp/Aeolis Mons). Hypotheses for mound formation include evaporitic, lacustrine, fluviodeltaic, and aeolian processes, but the origin and original extent of Gale’s mound is unknown. Here we show new measurements of sedimentary strata within the mound that indicate ∼3° outward dips oriented radially away from the mound center, inconsistent with the first three hypotheses. Moreover, although mounds are widely considered to be erosional remnants of a once crater-filling unit, we find that the Gale mound’s current form is close to its maximal extent. Instead we propose that the mound’s structure, stratigraphy, and current shape can be explained by growth in place near the center of the crater mediated by wind-topography feedbacks. Our model shows how sediment can initially accrete near the crater center far from crater-wall katabatic winds, until the increasing relief of the resulting mound generates mound-flank slope winds strong enough to erode the mound. The slope wind enhanced erosion and transport (SWEET) hypothesis indicates mound formation dominantly by aeolian deposition with limited organic carbon preservation potential, and a relatively limited role for lacustrine and fluvial activity. Morphodynamic feedbacks between wind and topography are widely applicable to a range of sedimentary and ice mounds across the Martian surface, and possibly other planets

Suppression of allergic airway inflammation by helminth-induced regulatory T cells

Allergic diseases mediated by T helper type (Th) 2 cell immune responses are rising dramatically in most developed countries. Exaggerated Th2 cell reactivity could result, for example, from diminished exposure to Th1 cell–inducing microbial infections. Epidemiological studies, however, indicate that Th2 cell–stimulating helminth parasites may also counteract allergies, possibly by generating regulatory T cells which suppress both Th1 and Th2 arms of immunity. We therefore tested the ability of the Th2 cell–inducing gastrointestinal nematode Heligmosomoides polygyrus to influence experimentally induced airway allergy to ovalbumin and the house dust mite allergen Der p 1. Inflammatory cell infiltrates in the lung were suppressed in infected mice compared with uninfected controls. Suppression was reversed in mice treated with antibodies to CD25. Most notably, suppression was transferable with mesenteric lymph node cells (MLNC) from infected animals to uninfected sensitized mice, demonstrating that the effector phase was targeted. MLNC from infected animals contained elevated numbers of CD4(+)CD25(+)Foxp3(+) T cells, higher TGF-β expression, and produced strong interleukin (IL)-10 responses to parasite antigen. However, MLNC from IL-10–deficient animals transferred suppression to sensitized hosts, indicating that IL-10 is not the primary modulator of the allergic response. Suppression was associated with CD4(+) T cells from MLNC, with the CD4(+)CD25(+) marker defining the most active population. These data support the contention that helminth infections elicit a regulatory T cell population able to down-regulate allergen induced lung pathology in vivo

Long-term storage and age‐biased export of fluvial organic carbon: field evidence from West Iceland

Terrestrial organic carbon (OC) plays an important role in the carbon cycle, but questions remain regarding the controls and timescale(s) over which atmospheric CO₂ remains sequestered as particulate OC (POC). Motivated by observations that terrestrial POC is physically stored within soils and other shallow sedimentary deposits, we examined the role that sediment storage plays in the terrestrial OC cycle. Specifically, we tested the hypothesis that sediment storage impacts the age of terrestrial POC. We focused on the Efri Haukadalsá River catchment in Iceland as it lacks ancient sedimentary bedrock that would otherwise bias radiocarbon‐based determinations of POC storage duration by supplying pre‐aged “petrogenic” POC. Our radiocarbon measurements of riverine suspended sediments and deposits implicated millennial‐scale storage times. Comparison between the sample types (suspended and deposits) suggested an age offset between transported (suspended sediments) and stored (deposits) POC at the time of sampling, which is predicted by theory for the sediment age distribution in floodplains. We also observed that POC in suspended sediments is younger than the predicted mean storage duration generated from independent geomorphological data, which suggested an additional role for OC cycling. Consistent with this, we observed interparticle heterogeneity in the composition of POC by imaging our samples at the microscale using X‐ray absorption spectroscopy. Specifically, we found that particles within individual samples differed in their sulfur oxidation state, which is indicative of multiple origins and/or diagenetic histories. Altogether, our results support recent coupled sediment storage and OC cycling models and indicate that the physical drivers of sediment storage are important factors controlling the cadence of carbon cycling

Do Economic Conditions Explain International Variation in Parenting Styles?

This thesis investigates the influence of economic conditions on parental attitudes and student performance using PISA and OECD data. In 2014, Matthias Doepke and Fabrizio Zilibotti published a paper theorizing that parenting styles emerge as equilibrium outcomes depending on both parental preferences and the economic environment (Doepke and Zilibotti, 2014). Their theory states that parents adopt more involved and overbearing parenting styles as the economic returns to student achievement rise. This thesis empirically tests Doepke and Zilibotti’s theory using the triennial PISA survey, and it further tests whether parenting styles directly influence student performance in math, science, and reading. My results support Doepke and Zilibotti’s theory by finding a positive relationship between the Wage Premium and Parental Dissatisfaction. I also find a negative relationship between Parental Dissatisfaction and Student Performance and a mixed relationship between the Wage Premium and Student Performance. The contribution of this thesis is empirical support for Doepke and Zilibotti’s theory and a creative and novel use of the PISA data

Reconciling Flourishing Egoism with Common Morality

It is a common critique of moral theories focused on the agent that they are selfish and immoral. Selfish here typically carries a negative connotation. Morality is supposed to show how we ought to treat people outside of ourselves; and this is true to a degree. But so often it seems, at least to me, that the more “selfless” moral theories seem to forget that the agent is as deserving of the good as those that the agent interacts with are. Egoism, broadly, reverses this and places the agent at the forefront of ethical decision-making. Unfortunately, this has historically led to theories that are perceived as harmful, immoral, and sentimentally repugnant. These reactions to concepts such as hedonistic egoism, psychological egoism, etc are understandable, and I agree with them much of the time. Nonetheless, I maintain that there is a version of Egoism that gets past these personal objections and triumphs as a positive ethical theory