Single-point failures of natural gas infrastructure can hamper methane emission control strategies designed to mitigate climate change. The 23 October 2015 blowout of a well connected to the Aliso ...Canyon underground storage facility in California resulted in a massive release of natural gas. Analysis of methane and ethane data from dozens of plume transects, collected during 13 research-aircraft flights between 7 November 2015 and 13 February 2016, shows atmospheric leak rates of up to 60 metric tons of methane and 4.5 metric tons of ethane per hour. At its peak, this blowout effectively doubled the methane emission rate of the entire Los Angeles basin and, in total, released 97,100 metric tons of methane to the atmosphere.
Abstract
Cosmic microwave background (CMB) lensing is a powerful probe of the matter distribution in the Universe. The standard quadratic estimator, which is typically used to measure the lensing ...signal, is known to be suboptimal for low-noise polarization data from next-generation experiments. In this paper, we explain why the quadratic estimator will also be suboptimal for measuring lensing on very small scales, even for measurements in temperature where this estimator typically performs well. Though maximum likelihood methods could be implemented to improve performance, we explore a much simpler solution, revisiting a previously proposed method to measure lensing that involves a direct inversion of the background gradient. An important application of this simple formalism is the measurement of cluster masses with CMB lensing. We find that directly applying a gradient inversion matched filter to simulated lensed images of the CMB can tighten constraints on cluster masses compared to the quadratic estimator. While the difference is not relevant for existing surveys, for future surveys it can translate to significant improvements in mass calibration for distant clusters, where galaxy lensing calibration is ineffective due to the lack of enough resolved background galaxies. Improvements can be as large as ${\sim } 50{{\ \rm per\ cent}}$ for a cluster at z = 2 and a next-generation CMB experiment with 1 $\mu$K arcmin noise, and over an order of magnitude for lower noise levels. For future surveys, this simple matched filter or gradient inversion method approaches the performance of maximum likelihood methods, at a fraction of the computational cost.
Research Summary: To further our understanding of how and why organizations engage in coopetition, we explore cooperative and competitive actions in the craft beer industry. Through an inductive ...field study, including interviews with craft brewery owners, we propose collective identity and collective norms play a critical role in the persistence of coopetition over time. Our process model suggests that (a) an oppositional collective identity, (b) the shared belief that a rising tide lifts all boats, and (c) the shared belief that advice and assistance should be paid forward, can lead to the persistence of coopetition beyond market category emergence.
Managerial Summary: This paper develops a theory of how smaller, craft‐based organizations (i.e., “Davids”) encourage cohesion and cooperation amongst themselves when operating against an incumbent market of mass‐producers (i.e., “Goliaths”). An ideological opposition to existing players can lead to a shared belief that helping organizations like your own benefits everyone—the rising tide lifts all boats mentality. Similarly, when organizations first enter a market and receive help from established members, they can feel compelled to help others who enter the market after—the pay‐it‐forward mentality. Together, these mechanisms offer an explanation as to how and why coopetition might persist in a market category over time.
In 2012, NASA's Curiosity rover landed on Mars to assess its potential as a habitat for past life and investigate the paleoclimate record preserved by sedimentary rocks inside the ...~150-kilometer-diameter Gale impact crater. Geological reconstructions from Curiosity rover data have revealed an ancient, habitable lake environment fed by rivers draining into the crater. We synthesize geochemical and mineralogical data from lake-bed mudstones collected during the first 1300 martian solar days of rover operations in Gale. We present evidence for lake redox stratification, established by depth-dependent variations in atmospheric oxidant and dissolved-solute concentrations. Paleoclimate proxy data indicate that a transition from colder to warmer climate conditions is preserved in the stratigraphy. Finally, a late phase of geochemical modification by saline fluids is recognized.
Existing categories often blend together to form new categories. To date, research has explored noncontroversial forms of category blending, such as smartphones and nanotechnology, even though ...category blending can frequently represent a highly contentious activity. Through an inductive field study of collegiate-licensed beer, we develop a theoretical model of contentious category blending. We show that contentious category blending related to and invoked tradition in three important ways. First, as contentiousness arises primarily from the participants involved in the category, opponents framed tradition narrowly—around those for whom the category was contentious (e.g., university students). Conversely, proponents framed tradition more broadly by incorporating stories of alumni, farmers, local craft breweries, and community members. By shifting the emphasis on tradition away from the actors for which the category was contentious and toward actors for which the category was appropriate, category proponents were able to establish a more lenient category and success in blending the categories. Second, whereas theory indicates that members of new categories generally seek to illustrate their novelty and distinctiveness from existing categories, we find the opposite among contentious category proponents. Instead, as contentiousness arouses questions about whether a product should exist, proponents draw from history, heritage, and tradition to demonstrate how elements of the product already exist. Third, we find the importance of tradition, culture, and community mean the legitimacy of a blended category does not so easily transfer but instead extends only to those communities that can uniquely stand on the traditions of their own community to gain support.
Photochemical smog, characterized by high concentrations of ozone (O3) and fine particles (PM2.5) in the atmosphere, has become one of the top environmental concerns in China. Volatile organic ...compounds (VOCs), one of the key precursors of O3 and secondary organic aerosol (SOA) (an important component of PM2.5), have a critical influence on atmospheric chemistry and subsequently affect regional and global climate. Thus, VOCs have been extensively studied in many cities and regions in China, especially in the North China Plain, the Yangtze River Delta and the Pearl River Delta regions where photochemical smog pollution has become increasingly worse over recent decades. This paper reviews the main studies conducted in China on the characteristics and sources of VOCs, their relationship with O3 and SOA, and their removal technology. This paper also provides an integrated literature review on the formulation and implementation of effective control strategies of VOCs and photochemical smog, as well as suggestions for future directions of VOCs study in China.
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•Characteristics and sources of VOCs in China are reviewed.•Relationship of VOCs with O3 and SOA in China are reviewed.•Integrated literature review on the control strategies of VOCs and photochemical smog is provided.•Future directions of VOC study in China are suggested.
Microtubule assembly is vital for many fundamental cellular processes. Current models for microtubule assembly kinetics assume that the subunit dissociation rate from a microtubule tip is independent ...of free subunit concentration. Total-Internal-Reflection-Fluorescence (TIRF) microscopy experiments and data from a laser tweezers assay that measures in vitro microtubule assembly with nanometer resolution, provides evidence that the subunit dissociation rate from a microtubule tip increases as the free subunit concentration increases. These data are consistent with a two-dimensional model for microtubule assembly, and are explained by a shift in microtubule tip structure from a relatively blunt shape at low free concentrations to relatively tapered at high free concentrations. We find that because both the association and the dissociation rates increase at higher free subunit concentrations, the kinetics of microtubule assembly are an order-of-magnitude higher than currently estimated in the literature.
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► Microtubule assembly kinetics are 10-fold more rapid than previously estimated ► Subunit on and off rates increase equally as tubulin concentration increases ► Tip structure changes as a function of free-tubulin concentration ► A 2-D model accurately describes multistranded biological self-assembly
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