The Effect of Market Structure on Pest Resistance Buildup

In this paper we present a continuous time optimal control analysis of resistance buildup in agricultural chemicals when the supplier is a monopolist. We compare the monopolistic, competitive and socially optimal solutions after establishing the stability of each equilibrium. The central finding is that with a monopolistic supplier, resistance buildup is lower than socially optimal. This directly opposes the standard result in the resistance literature. This implies that policies to manage resistance should vary with the age of the chemical, with no intervention during the lifetime of a patent and an optimal tax once the patent expires.Research Methods/ Statistical Methods,

Payments for Environmental Services: To whom, where, and how much?

In this paper we consider different strategies for implementing a payment for environmental services (PES) program to mitigate deforestation in Mexican common property forests (ejidos). We begin by discussing the policy context within which PES programs find themselves, highlighting other possible interventions to help preserve environmental amenities in Mexico. We then discuss some basic principles of environmental payment schemes, formalizing these into three that we simulate: payment of the opportunity cost for forests at risks; payment for environmental benefits provided by forests at risk; a flat payment scheme with a cap on allowable hectares, similar to the type of program often applied in developing countries; and a program of opportunity cost payments for forest at risk with highest environmental benefit per dollar paid. We find that, of these three, the last is most efficient and the second most egalitarian. We also repeat a simulation of the third scheme using predicted, rather than actual risk, which circumvents the problem of strategic behavior on the part of recipient communities but introduces some error into the targeting process. Finally, we consider the characteristics of communities that receive payments from the most efficient program, finding that larger and more remote ejidos receive the lion's share of the budget, but that payments to them are not necessarily more efficient. This scheme also gives more, though smaller on a per capita basis, payments to poor and indigenous communities, where they are more efficient than those to non-poor and non-indigenous ejidos.Environmental Economics and Policy,

THE INCREASING ROLE OF AGRIBUSINESS IN AGRICULTURAL ECONOMICS

While the demand for traditional agricultural economics is diminishing, there is a growing need for the economics and management of the food sector and the environment. Departments of agricultural economics have shown great flexibility in including agribusiness in their Bachelor's and Master's teaching programs. Ph.D and research programs appear to adjust more slowly to changing demand. Although agricultural economics programs are providing a variety of service course offerings, opportunities for joint programs with biological, physical, and natural sciences, particularly resource management, are not being exploited. If business schools decide to compete for agribusiness students in the future, missed opportunities with other departments and schools may become very costly. If this profession is to remain viable in the long run, it must continue to evolve, developing opportunities with biological, physical, and natural disciplines, in order to meet the demands of a changing market.agribusiness, agricultural economics, education, extension, research, Agribusiness, Teaching/Communication/Extension/Profession,

Combined effects of a parasite, QPX, and the harmful-alga, Prorocentrum minimum on northern quahogs, Mercenaria mercenaria

Northern quahogs, Mercenaria mercenaria (L.), frequently are infected with the parasite Quahog Parasite Unknown (QPX, Labyrintohomorpha, Thraustochytriales), which can cause morbidity and mortality of the quahogs. Possible interactions between this parasitic disease and exposure to the harmful dinoflagellate Prorocentrum minimum in M. mercenaria were studied experimentally. Quahogs from Massachusetts with variable intensity of QPX infection were exposed, under controlled laboratory conditions, to cultured P. minimum added to the natural plankton at a cell density equivalent to a natural bloom. After 5 days of exposure, individual clams were diagnosed histologically to assess prevalence and intensity of parasitic infection, as well as other pathological conditions. Further, cellular defense status of clams was evaluated by analyzing hemocyte parameters (morphological and functional) using flow-cytometry. Exposure of quahogs to P. minimum resulted in: a lower percentage of phagocytic hemocytes, higher production of reactive oxygen species (ROS), larger hemocyte size, more-numerous hemocytic aggregates, and increased numbers of hemocytes in gills accompanied by vacuolation and hyperplasia of the water-tubular epithelial cells of the gills. Quahogs had a low prevalence of QPX; by chance, the parasite was present only in quahogs exposed to P. minimum. Thus, the effect of QPX alone on the hemocyte parameters of quahogs could not be assessed in this experiment, but it was possible to assess different responses of infected versus non-infected quahogs to P. minimum. QPX-infected quahogs exposed to P. minimum had repressed percentage of phagocytic hemocytes, consistent with immuno-modulating effect of P. minimum upon several molluscan species, as well as smaller hemocytes and increased hemocyte infiltration throughout the soft tissues. This experiment demonstrates the importance of considering interactive effects of different factors on the immunology and histopathology of bivalve shellfish, and highlights the importance of considering the presence of parasites when bivalves are subjected to harmful-algal blooms

Trait Variation Along Elevation Gradients in a Dominant Wood Shrub is Population-Specific and Driven by Plasticity

Elevation gradients are frequently used as space-for-time substitutions to infer species’ trait responses to climate change. However, studies rarely investigate whether trait responses to elevation are widespread or population specific within a species, and the relative genetic and plastic contributions to such trait responses may not be well understood. Here, we examine plant trait variation in the dominant woody shrub, Rhododendron maximum, along elevation gradients in three populations in the South Central Appalachian Mountains, USA, in both field and common garden environments. We ask the following: (1) do plant traits vary along elevation? (2) do trait responses to elevation differ across populations, and if so, why? and (3) does genetic differentiation or phenotypic plasticity drive trait variation within and among populations? We found that internode length, shoot length, leaf dry mass, and leaf area varied along elevation, but that these responses were generally unique to one population, suggesting that trait responses to environmental gradients are population-specific. A common garden experiment identified nogenetic basis to variation along elevation or among populations in any trait, suggesting that plasticity drives local and regional trait variation and may play a key role in the persistence of plant species such as R. maximum with contemporary climate change. Overall, our findings highlight the importance of examining multiple locations in future elevation studies and indicate that, for a given plant species, the magnitude of trait responses to global climate change may vary by location

Transcranial Direct Current Stimulation Combined With Listening to Preferred Music Alters Cortical Speech Processing in Older Adults

Emerging evidence suggests transcranial direct current stimulation (tDCS) can improve cognitive performance in older adults. Similarly, music listening may improve arousal and stimulate subsequent performance on memory-related tasks. We examined the synergistic effects of tDCS paired with music listening on auditory neurobehavioral measures to investigate causal evidence of short-term plasticity in speech processing among older adults. In a randomized sham-controlled crossover study, we measured how combined anodal tDCS over dorsolateral prefrontal cortex (DLPFC) paired with listening to autobiographically salient music alters neural speech processing in older adults compared to either music listening (sham stimulation) or tDCS alone. EEG assays included both frequency-following responses (FFRs) and auditory event-related potentials (ERPs) to trace neuromodulation-related changes at brainstem and cortical levels. Relative to music without tDCS (sham), we found tDCS alone (without music) modulates the early cortical neural encoding of speech in the time frame of ∼100–150 ms. Whereas tDCS by itself appeared to largely produce suppressive effects (i.e., reducing ERP amplitude), concurrent music with tDCS restored responses to those of the music+sham levels. However, the interpretation of this effect is somewhat ambiguous as this neural modulation could be attributable to a true effect of tDCS or presence/absence music. Still, the combined benefit of tDCS+music (above tDCS alone) was correlated with listeners’ education level suggesting the benefit of neurostimulation paired with music might depend on listener demographics. tDCS changes in speech-FFRs were not observed with DLPFC stimulation. Improvements in working memory pre to post session were also associated with better speech-in-noise listening skills. Our findings provide new causal evidence that combined tDCS+music relative to tDCS-alone (i) modulates the early (100–150 ms) cortical encoding of speech and (ii) improves working memory, a cognitive skill which may indirectly bolster noise-degraded speech perception in older listeners

Ngaa-bi-nya-nhumi-nya (to test first) : piloting the feasibility of using the growth and empowerment measure with Aboriginal pregnant women who smoke

Introduction. Aboriginal pregnant women who smoke experience barriers to quitting, including challenges to social and emotional well-being, but these are infrequently quantified. Finding an appropriate measurement tool in this setting is crucial to increase knowledge for holistic smoking cessation interventions. Aims. To pilot the Growth and Empowerment Measure (GEM) with a sample of pregnant Aboriginal women who smoke. Methods. Aboriginal women participating in the step-wedge ICAN QUIT in Pregnancy pilot study completed the GEM comprised of 14-item Emotional Empowerment Scale (EES14), 12 Scenarios (12S), and K6 items at baseline, 4 weeks, and 12 weeks. Qualitative interviews with service staff were held at the end of the study to assess feasibility. Results. 15 pregnant Aboriginal women took part between November 2016 and July 2017. At 12 weeks, n=8/12 (67%) of women reported an increase in both the EES14 and 12S scores. Total 12S scores were significantly higher at 12 weeks (p=0.0186). Total K6 had a nonsignificant trend for reduction (p=0.0547). Staff reported that the length of the survey presents challenges in this setting. Conclusions. A shortened, modified GEM is recommended in this setting. We recommend the GEM to be tested in a larger study, powered to assess its associations with smoking behaviours

Model Systems to Study the Chronic, Polymicrobial Infections in Cystic Fibrosis: Current Approaches and Exploring Future Directions

A recent workshop titled “Developing Models to Study Polymicrobial Infections,” sponsored by the Dartmouth Cystic Fibrosis Center (DartCF), explored the development of new models to study the polymicrobial infections associated with the airways of persons with cystic fibrosis (CF). The workshop gathered 351 investigators over two virtual sessions. Here, we present the findings of this workshop, summarize some of the challenges involved with developing such models, and suggest three frameworks to tackle this complex problem. The frameworks proposed here, we believe, could be generally useful in developing new model systems for other infectious diseases. Developing and validating new approaches to study the complex polymicrobial communities in the CF airway could open windows to new therapeutics to treat these recalcitrant infections, as well as uncovering organizing principles applicable to chronic polymicrobial infections more generally

Can Government-Controlled Media Cause Social Change? Television and Fertility in India *

Abstract Does exposure to government-controlled media shape social attitudes and behaviors? Governments routinely enlist public broadcasting to advance progressive social change. However, the efficacy of so-called "developmental communications" is unclear. Modernization theorists contend that the media serve as an important instrument of persuasion in poor countries-especially among certain population groups. Yet, where institutionalization is weak, government-controlled outlets are often dominated by ruling-party propaganda, which may induce distrust in the media and its messaging campaigns. To adjudicate which of these propositions holds sway, we investigate television's impact on fertility preferences and behaviors in India. Exploiting unique data, as well as plausibly exogenous variation in TV ownership due to electromagnetic wave refraction, we show that exposure to India's monopolistic state broadcaster, Doordarshan, caused women to desire fewer children-especially fewer girls-while increasing family planning discussions and contraceptive use. The results demonstrate that even biased state media can engender far-reaching societal transformation. * We than