Cooperation and Cheating

In this article, we extend the variable delivery claim framework (Cross, Buccola, and Thomann, 2006) to examine the option-to-cheat, that is, the option to shift production between contracts ex post. We use this framework to provide a solution to the age-old conflict between enforcement and the cooperative tradition of providing a "home" for member produce. We show that, in contrast to Nourse's competitive yardstick hypothesis, the value of the cooperative-provided option increases as market competition intensifies. When the option-to-cheat is fairly-priced, it is Pareto improving, increasing grower returns, lowering cooperative per-unit costs and reducing contract shortfalls for investor-owned rivals at no additional per-unit cost. Our valuation framework is consistent with replication-based equilibria and is free from parametric specification of individual preference or firm cost structure.Marketing,

Limited antigenic diversity of Plasmodium falciparum apical membrane antigen 1 supports the development of effective multi-allele vaccines

BackgroundPolymorphism in antigens is a common mechanism for immune evasion used by many important pathogens, and presents major challenges in vaccine development. In malaria, many key immune targets and vaccine candidates show substantial polymorphism. However, knowledge on antigenic diversity of key antigens, the impact of polymorphism on potential vaccine escape, and how sequence polymorphism relates to antigenic differences is very limited, yet crucial for vaccine development. Plasmodium falciparum apical membrane antigen 1 (AMA1) is an important target of naturally-acquired antibodies in malaria immunity and a leading vaccine candidate. However, AMA1 has extensive allelic diversity with more than 60 polymorphic amino acid residues and more than 200 haplotypes in a single population. Therefore, AMA1 serves as an excellent model to assess antigenic diversity in malaria vaccine antigens and the feasibility of multi-allele vaccine approaches. While most previous research has focused on sequence diversity and antibody responses in laboratory animals, little has been done on the cross-reactivity of human antibodies.MethodsWe aimed to determine the extent of antigenic diversity of AMA1, defined by reactivity with human antibodies, and to aid the identification of specific alleles for potential inclusion in a multi-allele vaccine. We developed an approach using a multiple-antigen-competition enzyme-linked immunosorbent assay (ELISA) to examine cross-reactivity of naturally-acquired antibodies in Papua New Guinea and Kenya, and related this to differences in AMA1 sequence.ResultsWe found that adults had greater cross-reactivity of antibodies than children, although the patterns of cross-reactivity to alleles were the same. Patterns of antibody cross-reactivity were very similar between populations (Papua New Guinea and Kenya), and over time. Further, our results show that antigenic diversity of AMA1 alleles is surprisingly restricted, despite extensive sequence polymorphism. Our findings suggest that a combination of three different alleles, if selected appropriately, may be sufficient to cover the majority of antigenic diversity in polymorphic AMA1 antigens. Antigenic properties were not strongly related to existing haplotype groupings based on sequence analysis.ConclusionsAntigenic diversity of AMA1 is limited and a vaccine including a small number of alleles might be sufficient for coverage against naturally-circulating strains, supporting a multi-allele approach for developing polymorphic antigens as malaria vaccines

Symplastic solute transport and avocado fruit development : a decline in cytokinin/ABA ratio is related to appearance of the Hass small fruit variant

Studies on the effect of fruit size on endogenous ABA and isopentenyladenine (iP) in developing avocado (Persea americana Mill. cv. Hass) fruit revealed that ABA content was negatively correlated with fruit size whilst the iP/ABA ratio showed a linear relationship with increasing size of fruit harvested 226 d after full bloom. The effect of this change in hormone balance on the relationship between symplastic solute transport and appearance of the small fruit variant was examined following manipulation of the endogenous cytokinin (CK)/ABA ratio. Application of ABA caused seed coat senescence and retarded fruit growth but these effects were absent in fruit treated with equal amounts of ABA plus iP. Thus, the underlying physiological mechanisms associated with ABA-induced retardation of Hass avocado fruit growth appeared to be inextricably linked to a decline in CK content and included: diminution of mesocarp and seed coat plasmodesmatal branching, gating of mesocarp and seed coat plasmodesmata by deposition of electron dense material in the neck region, abolishment of the electrochemical gradient between mesocarp and seed coat parenchyma, and arrest of cell-to-cell chemical communication

Canceled: A New Reliability Incentive for Energy-Only Electricity Markets

This paper considers the reliability problem in energy-only markets. Following widespread blackouts in 2011, Texas introduced a reliability price incentive to attract two GW of net additional natural gas-generating capacity. The incentive is unusual because energy buyers pay the incentive directly to producers in a real-time spot market. The program has created $13 billion in direct payments to generators annually since 2015 and is now being implemented or considered in several major energy markets in the US and abroad. We assess the incentive's impact on the Texas market from three perspectives: First, we derive the incentive's equilibrium effect on the electricity price in a monopolistic market from first principles using a standard partial equilibrium economic model. We then empirically test whether the incentive encouraged net entry into the market or the generating applicant pool, controlling for market and climatic conditions using monthly capacity data. Finally, we look for direct evidence of an incentive response among active traders using real-time market trading data. The three approaches suggest buyers and producers cancel out the incentive, and the price-only program does not encourage new generation capacity to enter the market

Causal Orthogonalization: Multicollinearity, Economic Interpretability, and the Gram-Schmidt Process

This paper considers the problem of interpreting orthogonalization model coefficients. We derive a causal economic interpretation of the Gram-Schmidt orthogonalization process and provide the conditions for its equivalence to total effects from a recursive Directed Acyclic Graph. We extend the Gram-Schmidt process to groups of simultaneous regressors common in economic data sets and derive its finite sample properties, finding its coefficients to be unbiased, stable, and more efficient than those from Ordinary Least Squares. Finally, we apply the estimator to childhood reading comprehension scores, controlling for such highly collinear characteristics as race, education, and income. The model expands Bohren et al.'s decomposition of systemic discrimination into channel-specific effects and improves its coefficient significance levels

Essays in incomplete agricultural markets

Agricultural revenues, the product of stochastic prices and yields, lead to markets which are incomplete, thereby entreating and complicating economic inquiry. The following three essays explore the incomplete nature of agricultural markets and consider the implications of incompleteness for a range of policy questions and economic tools. The first essay, "Cooperative Pricing Policy Under Stress: The Case of Tn Valley Growers," explores the incomplete contract markets that arise from unobservable yield processes. I formalize a common class of forward contracts, decompose them into a convex combination of yield derivatives, then derive the arbitrage-free forward price bounds. These bounds are used to show how the Board of Directors of a large agricultural cooperative, Tri Valley Growers, overstated earnings in order to liquidate financial equity. The second essay, "Adapting Cooperative Structure for the New Global Environment," follows up on the first by showing that the liquidating strategy Tn Valley's Board pursued was rational in terms of maximizing expected net present value of future cash flows, I derive a condition under which optimal equity retention is strictly greater for investor-owned than for cooperatively owned firms. Finally, I use ruin probabilities associated with the standard firstcrossing- time problem, together with numerical integration methods, to verify that this condition held under the market conditions in which Tn Valley and its investor-owned rivals operated. The third essay, "DEA and The Law of One Price," explores the effect of variable prices on technical efficiency estimation. Data commonly are furnished in value, rather than factor terms. This raises the question of how value-based DEA models coincide with factor-based models. A sufficient condition for the two models to coincide is that all firms face the same set of prices. In practice, however, prices commonly vary across firms. I show that, unless an unreasonable restriction holds, the two models do not coincide. I decompose the resulting estimation error into its technology and firm-related components. Using Farrell's original 1957 data set to illustrate, the resulting estimation error is found to be both systematic and one-sided

Automated Analysis of Cryptococcal Macrophage Parasitism Using GFP-Tagged Cryptococci

The human fungal pathogens Cryptococcus neoformans and C. gattii cause life-threatening infections of the central nervous system. One of the major characteristics of cryptococcal disease is the ability of the pathogen to parasitise upon phagocytic immune effector cells, a phenomenon that correlates strongly with virulence in rodent models of infection. Despite the importance of phagocyte/Cryptococcus interactions to disease progression, current methods for assaying virulence in the acrophage system are both time consuming and low throughput. Here, we introduce the first stable and fully characterised GFP–expressing derivatives of two widely used cryptococcal strains: C. neoformans serotype A type strain H99 and C. gattii serotype B type strain R265. Both strains show unaltered responses to environmental and host stress conditions and no deficiency in virulence in the macrophage model system. In addition, we report the development of a method to effectively and rapidly investigate macrophage parasitism by flow cytometry, a technique that preserves the accuracy of current approaches but offers a four-fold improvement in speed

<i>Gaia</i> Data Release 1. Summary of the astrometric, photometric, and survey properties

Context. At about 1000 days after the launch of Gaia we present the first Gaia data release, Gaia DR1, consisting of astrometry and photometry for over 1 billion sources brighter than magnitude 20.7. Aims. A summary of Gaia DR1 is presented along with illustrations of the scientific quality of the data, followed by a discussion of the limitations due to the preliminary nature of this release. Methods. The raw data collected by Gaia during the first 14 months of the mission have been processed by the Gaia Data Processing and Analysis Consortium (DPAC) and turned into an astrometric and photometric catalogue. Results. Gaia DR1 consists of three components: a primary astrometric data set which contains the positions, parallaxes, and mean proper motions for about 2 million of the brightest stars in common with the HIPPARCOS and Tycho-2 catalogues – a realisation of the Tycho-Gaia Astrometric Solution (TGAS) – and a secondary astrometric data set containing the positions for an additional 1.1 billion sources. The second component is the photometric data set, consisting of mean G-band magnitudes for all sources. The G-band light curves and the characteristics of ∼3000 Cepheid and RR-Lyrae stars, observed at high cadence around the south ecliptic pole, form the third component. For the primary astrometric data set the typical uncertainty is about 0.3 mas for the positions and parallaxes, and about 1 mas yr−1 for the proper motions. A systematic component of ∼0.3 mas should be added to the parallax uncertainties. For the subset of ∼94 000 HIPPARCOS stars in the primary data set, the proper motions are much more precise at about 0.06 mas yr−1. For the secondary astrometric data set, the typical uncertainty of the positions is ∼10 mas. The median uncertainties on the mean G-band magnitudes range from the mmag level to ∼0.03 mag over the magnitude range 5 to 20.7. Conclusions. Gaia DR1 is an important milestone ahead of the next Gaia data release, which will feature five-parameter astrometry for all sources. Extensive validation shows that Gaia DR1 represents a major advance in the mapping of the heavens and the availability of basic stellar data that underpin observational astrophysics. Nevertheless, the very preliminary nature of this first Gaia data release does lead to a number of important limitations to the data quality which should be carefully considered before drawing conclusions from the data

The Scottish Early Rheumatoid Arthritis (SERA) Study:an inception cohort and biobank

Background: The Scottish Early Rheumatoid Arthritis (SERA) study is an inception cohort of rheumatoid (RA) and undifferentiated arthritis (UA) patients that aims to provide a contemporary description of phenotype and outcome and facilitate discovery of phenotypic and prognostic biomarkers Methods: Demographic and clinical outcome data are collected from newly diagnosed RA/UA patients every 6 months from around Scotland. Health service utilization data is acquired from Information Services Division, NHS National Services Scotland. Plain radiographs of hands and feet are collected at baseline and 12 months. Additional samples of whole blood, plasma, serum and filtered urine are collected at baseline, 6 and 12 months Results: Results are available for 1073 patients; at baseline, 76 % were classified as RA and 24 % as UA. Median time from onset to first review was 163 days (IQR97-323). Methotrexate was first-line DMARD for 75 % patients. Disease activity, functional ability and health-related quality of life improved significantly between baseline and 24 months, however the proportion in any employment fell (51 to 38 %, p = 0.0005). 24 % patients reported symptoms of anxiety and/or depression at baseline. 35/391 (9 %) patients exhibited rapid radiographic progression after 12 months. The SERA Biobank has accrued 60,612 samples Conclusions: In routine care, newly diagnosed RA/UA patients experience significant improvements in disease activity, functional ability and health-related quality of life but have high rates of psychiatric symptoms and declining employment rates. The co-existence of a multi-domain description of phenotype and a comprehensive biobank will facilitate multi-platform translational research to identify predictive markers of phenotype and prognosis

The state of the Martian climate

60°N was +2.0°C, relative to the 1981–2010 average value (Fig. 5.1). This marks a new high for the record. The average annual surface air temperature (SAT) anomaly for 2016 for land stations north of starting in 1900, and is a significant increase over the previous highest value of +1.2°C, which was observed in 2007, 2011, and 2015. Average global annual temperatures also showed record values in 2015 and 2016. Currently, the Arctic is warming at more than twice the rate of lower latitudes