•The last 27 years of FACE (free-air CO2 enrichment) experiments were reviewed.•Elevated CO2 decreased evapotranspiration of both C3 and C4 plants about 10%.•Yields of most C3 grain crops were ...increased on average about 19%.•Yields of C4 species were unchanged with ample water, but increased 30% with limited water.•Yield increases due to increased CO2 were variable with increased temperature.
About twenty-seven years ago, free-air CO2 enrichment (FACE) technology was developed that enabled the air above open-field plots to be enriched with CO2 for entire growing seasons. Since then, FACE experiments have been conducted on cotton, wheat, ryegrass, clover, potato, grape, rice, barley, sugar beet, soybean, cassava, rape, mustard, coffee (C3 crops), and sorghum and maize (C4 crops). Elevated CO2 (550ppm from an ambient concentration of about 353ppm in 1990) decreased evapotranspiration about 10% on average and increased canopy temperatures about 0.7°C. Biomass and yield were increased by FACE in all C3 species, but not in C4 species except when water was limiting. Yields of C3 grain crops were increased on average about 19%.
The vomiting (emetic) reflex is documented in numerous mammalian species, including primates and carnivores, yet laboratory rats and mice appear to lack this response. It is unclear whether these ...rodents do not vomit because of anatomical constraints (e.g., a relatively long abdominal esophagus) or lack of key neural circuits. Moreover, it is unknown whether laboratory rodents are representative of Rodentia with regards to this reflex. Here we conducted behavioral testing of members of all three major groups of Rodentia; mouse-related (rat, mouse, vole, beaver), Ctenohystrica (guinea pig, nutria), and squirrel-related (mountain beaver) species. Prototypical emetic agents, apomorphine (sc), veratrine (sc), and copper sulfate (ig), failed to produce either retching or vomiting in these species (although other behavioral effects, e.g., locomotion, were noted). These rodents also had anatomical constraints, which could limit the efficiency of vomiting should it be attempted, including reduced muscularity of the diaphragm and stomach geometry that is not well structured for moving contents towards the esophagus compared to species that can vomit (cat, ferret, and musk shrew). Lastly, an in situ brainstem preparation was used to make sensitive measures of mouth, esophagus, and shoulder muscular movements, and phrenic nerve activity–key features of emetic episodes. Laboratory mice and rats failed to display any of the common coordinated actions of these indices after typical emetic stimulation (resiniferatoxin and vagal afferent stimulation) compared to musk shrews. Overall the results suggest that the inability to vomit is a general property of Rodentia and that an absent brainstem neurological component is the most likely cause. The implications of these findings for the utility of rodents as models in the area of emesis research are discussed.
► We reviewed 221 papers that used crop models to assess impacts of climate change. ► Crops most frequently assessed were wheat, maize, soybean and rice. ► Models predominantly used radiation use ...efficiency-based approaches. ► Assumed low baseline CO
2 may exaggerate projected impacts of increased CO
2. ► Coordinated data resources and model intercomparisons may enhance impact studies.
Ecophysiological models are widely used to forecast potential impacts of climate change on future agricultural productivity and to examine options for adaptation by local stakeholders and policy makers. However, protocols followed in such assessments vary to such an extent that they constrain cross-study syntheses and increase the potential for bias in projected impacts. We reviewed 221 peer-reviewed papers that used crop simulation models to examine diverse aspects of how climate change might affect agricultural systems. Six subject areas were examined: target crops and regions; the crop model(s) used and their characteristics; sources and application of data on CO
2 and climate; impact parameters evaluated; assessment of variability or risk; and adaptation strategies. Wheat, maize, soybean and rice were considered in approximately 170 papers. The USA (55 papers) and Europe (64 papers) were the dominant regions studied. The most frequent approach used to simulate response to CO
2 involved adjusting daily radiation use efficiency (RUE) and transpiration, precluding consideration of the interacting effects of CO
2, stomatal conductance and canopy temperature, which are expected to exacerbate effects of global warming. The assumed baseline CO
2 typically corresponded to conditions 10–30 years earlier than the date the paper was accepted, exaggerating the relative impacts of increased CO
2. Due in part to the diverse scenarios for increases in greenhouse gas emissions, assumed future CO
2 also varied greatly, further complicating comparisons among studies. Papers considering adaptation predominantly examined changes in planting dates and cultivars; only 20 papers tested different tillage practices or crop rotations. Risk was quantified in over half the papers, mainly in relation to variability in yield or effects of water deficits, but the limited consideration of other factors affecting risk beside climate change per se suggests that impacts of climate change were overestimated relative to background variability. A coordinated crop, climate and soil data resource would allow researchers to focus on underlying science. More extensive model intercomparison, facilitated by modular software, should strengthen the biological realism of predictions and clarify the limits of our ability to forecast agricultural impacts of climate change on crop production and associated food security as well as to evaluate potential for adaptation.
Colleges and universities are richer than ever—so why has the price of attending them risen so much?As endowments and fundraising campaigns have skyrocketed in recent decades, critics have attacked ...higher education for steeply increasing its production cost and price and the snowballing debt of students. In Wealth, Cost, and Price in American Higher Education, Bruce A. Kimball and Sarah M. Iler reveal how these trends began 150 years ago and why they have intensified in recent decades.In the late nineteenth century, American colleges and universities began fiercely competing to expand their revenue, wealth, and production cost in order to increase their quality and prestige and serve the soaring number of students. From that era through today, the rising wealth and cost of higher education have continued to reinforce each other and spiral upward, increasing the heavily subsidized price paid by students. Kimball and Iler explain the strategy and reasoning that drove this wealth-cost double helix, the new tactics in fundraising and endowment investing that fueled it, and economists' efforts to understand it.Using extensive archival, documentary, and quantitative research, Kimball and Iler trace the shifting public perception of higher education and its correlation with rising costs, stagnating wages, and explosive student debt. They show how stratification of wealth in higher education became tightly interwoven with wealth inequality in American society. This relationship raises fundamental questions about equity in US higher education and its contribution to social mobility and democracy.
A history of Harvard Law School in the twentieth century, focusing on the school's precipitous decline prior to 1945 and its dramatic postwar resurgence amid national crises and internal discord. By ...the late nineteenth century, Harvard Law School had transformed legal education and become the preeminent professional school in the nation. But in the early 1900s, HLS came to the brink of financial failure and lagged its peers in scholarly innovation. It also honed an aggressive intellectual culture famously described by Learned Hand: "In the universe of truth, they lived by the sword. They asked no quarter of absolutes, and they gave none." After World War II, however, HLS roared back. In this magisterial study, Bruce Kimball and Daniel Coquillette chronicle the school's near collapse and dramatic resurgence across the twentieth century.The school's struggles resulted in part from a debilitating cycle of tuition dependence, which deepened through the 1940s, as well as the suicides of two deans and the dalliance of another with the Nazi regime. HLS stubbornly resisted the admission of women, Jews, and African Americans, and fell behind the trend toward legal realism. But in the postwar years, under Dean Erwin Griswold, the school's resurgence began, and Harvard Law would produce such major political and legal figures as Chief Justice John Roberts, Justice Elena Kagan, and President Barack Obama. Even so, the school faced severe crises arising from the civil rights movement, the Vietnam War, Critical Legal Studies, and its failure to enroll and retain people of color and women, including Justice Ruth Bader Ginsburg.Based on hitherto unavailable sources—including oral histories, personal letters, diaries, and financial records— The Intellectual Sword paints a compelling portrait of the law school widely considered the most influential in the world.
Recent avian influenza infection outbreaks have resulted in global biosecurity and economic concerns. Mallards are asymptomatic for the disease and can potentially spread AI along migratory bird ...flyways. In a previous study, trained mice correctly discriminated the health status of individual ducks on the basis of fecal odors when feces from post-infection periods were paired with feces from pre-infection periods. Chemical analyses indicated that avian influenza infection was associated with a marked increase of acetoin (3-hydroxy-2-butanone) in feces. In the current study, domesticated male ferrets (Mustela putorius furo) were trained to display a specific conditioned response (i.e. active scratch alert) in response to a marked increase of acetoin in a presentation of an acetoin:1-octen-3-ol solution. Ferrets rapidly generalized this learned response to the odor of irradiated feces from avian influenza infected mallards. These results suggest that a trained mammalian biosensor could be employed in an avian influenza surveillance program.
► Identifying genetic markers for yield requires rapid quantification of crop traits. ► Proximal sensing offers promise for field-based phenotyping (FBP). ► Efficient data integration and ...modeling-assisted analysis are key for FBP. ► FBP scaled to thousands of field plots is a feasible, attainable goal. ► FBP systems require new, integrative collaborations that cross disciplines.
A major challenge for crop research in the 21st century is how to predict crop performance as a function of genetic architecture. Advances in “next generation” DNA sequencing have greatly improved genotyping efficiency and reduced genotyping costs. Methods for characterizing plant traits (phenotypes), however, have much progressed more slowly over the past 30 years, and constraints in phenotyping capability limit our ability to dissect the genetics of quantitative traits, especially those related to harvestable yield and stress tolerance. As a case in point, mapping populations for major crops may consist of 20 or more families, each represented by as many as 200 lines, necessitating field trials with over 20,000 plots at a single location. Investing in the resources and labor needed to quantify even a few agronomic traits for linkage with genetic markers in such massive populations is currently impractical for most breeding programs. Herein, we define key criteria, experimental approaches, equipment and data analysis tools required for robust, high-throughput field-based phenotyping (FBP). The focus is on simultaneous proximal sensing for spectral reflectance, canopy temperature, and plant architecture where a vehicle carrying replicated sets of sensors records data on multiple plots, with the potential to record data throughout the crop life cycle. The potential to assess traits, such as adaptations to water deficits or acute heat stress, several times during a single diurnal cycle is especially valuable for quantifying stress recovery. Simulation modeling and related tools can help estimate physiological traits such as canopy conductance and rooting capacity. Many of the underlying techniques and requisite instruments are available and in use for precision crop management. Further innovations are required to better integrate the functions of multiple instruments and to ensure efficient, robust analysis of the large volumes of data that are anticipated. A complement to the core proximal sensing is high-throughput phenotyping of specific traits such as nutrient status, seed composition, and other biochemical characteristics, as well as underground root architecture. The ability to “ground truth” results with conventional measurements is also necessary. The development of new sensors and imaging systems undoubtedly will continue to improve our ability to phenotype very large experiments or breeding nurseries, with the core FBP abilities achievable through strong interdisciplinary efforts that assemble and adapt existing technologies in novel ways.
Extensive evidence shows that increasing carbon dioxide concentration (CO₂) stimulates, and increasing temperature decreases, both net photosynthetic carbon assimilation (A) and biomass production ...for C₃ plants. However the CO₂-induced stimulation in A is projected to increase further with warmer temperature. While the influence of increasing temperature and CO₂, independent of each other, on A and biomass production have been widely investigated, the interaction between these two major global changes has not been tested on field-grown crops. Here, the interactive effect of both elevated CO₂ (approximately 585 µmol⁻¹) and temperature (+3.5°C) on soybean (Glycine max) A, biomass, and yield were tested over two growing seasons in the Temperature by Free-Air CO₂ Enrichment experiment at the Soybean Free Air CO₂ Enrichment facility. Measurements of A, stomatal conductance, and intercellular CO₂ were collected along with meteorological, water potential, and growth data. Elevated temperatures caused lower A, which was largely attributed to declines in stomatal conductance and intercellular CO₂ and led in turn to lower yields. Increasing both CO₂ and temperature stimulated A relative to elevated CO₂ alone on only two sampling days during 2009 and on no days in 2011. In 2011, the warmer of the two years, there were no observed increases in yield in the elevated temperature plots regardless of whether CO₂ was elevated. All treatments lowered the harvest index for soybean, although the effect of elevated CO₂ in 2011 was not statistically significant. These results provide a better understanding of the physiological responses of soybean to future climate change conditions and suggest that the potential is limited for elevated CO₂ to mitigate the influence of rising temperatures on photosynthesis, growth, and yields of C₃ crops.
There is a need for methodology to warm open-field plots in order to study the likely effects of global warming on ecosystems in the future. Herein, we describe the development of arrays of more ...powerful and efficient infrared heaters with ceramic heating elements. By tilting the heaters at 45° from horizontal and combining six of them in a hexagonal array, good uniformity of warming was achieved across 3-m-diameter plots. Moreover, there do not appear to be obstacles (other than financial) to scaling to larger plots. The efficiency ηh (%); thermal radiation out per electrical energy in of these heaters was higher than that of the heaters used in most previous infrared heater experiments and can be described by: ηh= 10 + 25exp(- 0.17 μ), where μ is wind speed at 2 m height (m s-1). Graphs are presented to estimate operating costs from degrees of warming, two types of plant canopy, and site windiness. Four such arrays were deployed over plots of grass at Haibei, Qinghai, China and another at Cheyenne, Wyoming, USA, along with corresponding reference plots with dummy heaters. Proportional integral derivative systems with infrared thermometers to sense canopy temperatures of the heated and reference plots were used to control the heater outputs. Over month-long periods at both sites, about 75% of canopy temperature observations were within 0.5 °C of the set-point temperature differences between heated and reference plots. Electrical power consumption per 3-m-diameter plot averaged 58 and 80 kW h day-1 for Haibei and Cheyenne, respectively. However, the desired temperature differences were set lower at Haibei (1.2 °C daytime, 1.7 °C night) than Cheyenne (1.5 °C daytime, 3.0 °C night), and Cheyenne is a windier site. Thus, we conclude that these hexagonal arrays of ceramic infrared heaters can be a successful temperature free-air-controlled enhancement (T-FACE) system for warming ecosystem field plots.
The rise of e-cigarette popularity has sparked interest in the role of palatable flavors on nicotine use. Despite growing evidence that sweet flavorants enhance nicotine reward, their influence on ...nicotine consumption has not been studied extensively. In addition, the impact that flavored nicotine use in adolescence could have on nicotine reward and dependence in adulthood remains unclear. This study examined the role of flavored nicotine access on nicotine preference and consumption longitudinally, from adolescence to adulthood. Male and female adolescent mice preferred a fruit-flavored nicotine solution over an unflavored nicotine solution. However, only adolescent female mice with access to flavored nicotine consumed higher doses. Furthermore, while adolescent male mice escalated consumption of both flavored and unflavored nicotine, female mice only escalated nicotine consumption when given access to flavored nicotine. As mice matured into adulthood, there was no evidence that a history of flavored-nicotine access altered preference for unflavored nicotine compared to a nicotine-free control in a classic two-bottle choice design. However, when the nicotine concentration was progressively reduced, mice that had consumed strawberry-flavored nicotine in adolescence maintained baseline nicotine consumption levels longer than mice that initiated nicotine use without flavor in adolescence. Finally, addition of fruit-flavorants into the nicotine solution during adulthood led to nicotine preference and increased levels of nicotine consumption, regardless of previous flavored-nicotine access or of familiarity with the selected flavorant. These results indicate that flavorants increase nicotine consumption independent of life stage, possibly posing a disproportionate risk to adolescent females. Our results also point to an effect of adolescent flavored-nicotine use on nicotine dose maintenance in adulthood, which could have implications for the success of future quit attempts.
•Adolescent mice prefer a fruit-flavored nicotine solution over an unflavored nicotine solution.•Adolescent female mice consume more nicotine if it is flavored.•Adolescent female mice escalate nicotine consumption only when flavored.•Adult mice with a history of flavored nicotine use resist nicotine dose reductions.•Adult mice increase nicotine consumption when flavor is added.
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