Evaluating emissions reductions from zero waste strategies under dynamic conditions: A case study from Boston

In 2018 and 2019 the City of Boston (Massachusetts, USA) conducted zero waste and carbon neutral planning efforts. Here we present the results of an accompanying analysis of the impacts of zero waste strategies on greenhouse gases (GHG) emissions associated with waste treatment. Emissions analysis in the waste sector is complicated by the contribution of significant indirect impacts that can exhibit temporal and spatial heterogeneity. For example, lifecycle GHG analysis of waste-to-energy combustion grants credits for the emissions avoided due to electricity generated from organic waste (biogenic carbon) that displaces electricity generation that could be carbon-emitting. As electricity grids decarbonize, this credit approaches zero. Long-term emissions planning needs to account for such dynamics to realistically assess the GHG mitigation potential associated with alternative waste management strategies. Here, we seek to capture these dynamics in a forward-looking analysis of waste sector emissions under a zero-waste strategy for the City of Boston. Using publicly available data sets such as EPA's Waste Reduction Model (WARM), we show that the implementation of zero waste strategies reduces the combustion of plastics and biomass in waste-to-energy (WtE) combustion facilities and associated GHG emissions. While WtE has been considered less-carbon intensive than other forms of waste treatment and fossil-based electricity generation, our analysis shows that more renewables will eventually eliminate the perceived GHG benefits associated with waste-to-energy combustion. While our approach provides policymakers with an understanding of the impacts of decisions in a dynamic context, we also identify common knowledge gaps in conducting forward-looking waste-GHG assessments.

Brazilian free-tailed bats as insect pest regulators in transgenic and conventional cotton crops

During the past 12000 years agricultural systems have transitioned from natural habitats to conventional agricultural regions and recently to large areas of genetically engineered (GE) croplands. This GE revolution occurred for cotton in a span of slightly more than a decade during which a switch occurred in major cotton production areas from growing 100% conventional cotton to an environment in which 95% transgenics are grown. Ecological interactions between GE targeted insects and other insectivorous insects have been investigated. However, the relationships between ecological functions (such as herbivory and ecosystem transport) and agronomic benefits of avian or mammalian insectivores in the transgenic environment generally remain unclear, although the importance of some agricultural pest management services provided by insectivorous species such as the Brazilian free-tailed bat, Tadarida brasiliensis, have been recognized. We developed a dynamic model to predict regional-scale ecological functions in agricultural food webs by using the indicators of insect pest herbivory measured by cotton boll damage and insect emigration from cotton. In the south-central Texas Winter Garden agricultural region we find that the process of insectivory by bats has a considerable impact on both the ecology and valuation of harvest in Bacillus thuringiensis (Bt) transgenic and nontransgenic cotton crops. Predation on agricultural pests by insectivorous bats may enhance the economic value of agricultural systems by reducing the frequency of required spraying and delaying the ultimate need for new pesticides. In the Winter Garden region, the presence of large numbers of insectivorous bats yields a regional summer dispersion of adult pest insects from Bt cotton that is considerably reduced from the moth emigration when bats are absent in either transgenic or non-transgenic crops. This regional decrease of pest numbers impacts insect herbivory on a transcontinental scale. With a few exceptions, we find that the agronomics of both Bt and conventional cotton production is more profitable when large numbers of insectivorous bats are present.

Surgical applications of organ preconditioning

In 1986, Murry et al. reported that brief periods of antecedent ischemia in dogs paradoxically reduced (rather than exacerbated) the size of myocardial infarcts created by subsequent prolonged ischemia. This fortuitous discovery, now termed "preconditioning", stimulated further investigation of the inherent adaptive mechanisms present in a variety of tissues and organs. In addition to ischemia, it is now recognized that a protective response can be initiated by multiple means including lipopolysaccharide, heat stress, exercise, adrenergic drugs and even noise. Furthermore, preconditioning protects not only against cell death but also against postischemic contractile dysfunction, stunning and arrhythmias. Despite the preponderance of animal studies demonstrating the benefits of preconditioning, its clinical application has been hampered by clinicians' hesitancy to intentionally subject patients to a noxious stress prior to a planned intervention. However, many of the intracellular signals responsible for the protective effect of preconditioning have been delineated, and pharmacologic manipulation of these signals can accomplish the same benefits. The existence of preconditioning in humans has been demonstrated in vitro and in small clinical trials, and targeted strategies that exploit this endogenous protective mechanism promise to broaden the therapeutic potential of organ preconditioning.

Energy and the U.S. Economy: A Biophysical Perspective

A series of hypotheses is presented about the relation of national energy use to national economic activity (both time series and cross-sectional) which offer a different perspective from standard economics for the assessment of historical and current economic events. The analysis incorporates nearly 100 years of time series data and 3 years of cross-sectional data on 87 sectors of the United States economy. Gross national product, labor productivity, and price levels are all correlated closely with various aspects of energy use, and these correlations are improved when corrections are made for energy quality. A large portion of the apparent increase in U.S. energy efficiency has been due to our ability to expand the relative use of high-quality fuels such as petroleum and electricity, and also to relative shifts in fuel use between sectors of the economy. The concept of energy return on investment is introduced as a major driving force in our economy, and data are provided which show a marked decline in energy return on investment for all our principal fuels in recent decades. Future economic growth will depend largely on the net energy yield of alternative fuel sources, and some standard economic models may need to be modified to account for the biophysical constraints on human economic activity.

Petroleum Drilling and Production in the United States: Yield per Effort and Net Energy Analysis

For the past three decades the quantity of petroleum (both oil and oil plus gas) found per foot of drilling effort in the United States for any given year can be expressed as a secular decrease of about 2 percent per year combined with an inverse function of drilling effort for that year. Extrapolation of energy costs and gains from petroleum drilling and extraction indicates that drilling for domestic petroleum could cease to be a net source of energy by about 2004 at low drilling rates and by 2000 or sooner at high drilling rates, and that the net yield will be less at higher drilling rates.