The impact of historical land use change from 1850 to 2000 on particulate matter and ozone

Anthropogenic land use change (LUC) since pre-industrial (1850) has altered the vegetation distribution and density around the world. We use a global model (GEOS-Chem) to assess the attendant changes in surface air quality and the direct radiative forcing (DRF). We focus our analysis on secondary particulate matter and tropospheric ozone formation. The general trend of expansion of managed ecosystems (croplands and pasturelands) at the expense of natural ecosystems has led to an 11 % decline in global mean biogenic volatile organic compound emissions. Concomitant growth in agricultural activity has more than doubled ammonia emissions and increased emissions of nitrogen oxides from soils by more than 50 %. Conversion to croplands has also led to a widespread increase in ozone dry deposition velocity. Together these changes in biosphere-atmosphere exchange have led to a 14 % global mean increase in biogenic secondary organic aerosol (BSOA) surface concentrations, a doubling of surface aerosol nitrate concentrations, and local changes in surface ozone of up to 8.5 ppb. We assess a global mean LUC-DRF of +0.017 Wm−2, −0.071 Wm−2, and −0.01 Wm−2 for BSOA, nitrate, and tropospheric ozone, respectively. We conclude that the DRF and the perturbations in surface air quality associated with LUC are substantial and should be considered alongside changes in anthropogenic emissions and climate feedbacks in chemistry-climate studies.https://www.atmos-chem-phys.net/16/14997/2016/acp-16-14997-2016.pdfhttps://www.atmos-chem-phys.net/16/14997/2016/acp-16-14997-2016.pdfPublished versio

Histone H1 is essential for mitotic chromosome architecture and segregation in Xenopus laevis egg extracts.

During cell division, condensation and resolution of chromosome arms and the assembly of a functional kinetochore at the centromere of each sister chromatid are essential steps for accurate segregation of the genome by the mitotic spindle, yet the contribution of individual chromatin proteins to these processes is poorly understood. We have investigated the role of embryonic linker histone H1 during mitosis in Xenopus laevis egg extracts. Immunodepletion of histone H1 caused the assembly of aberrant elongated chromosomes that extended off the metaphase plate and outside the perimeter of the spindle. Although functional kinetochores assembled, aligned, and exhibited poleward movement, long and tangled chromosome arms could not be segregated in anaphase. Histone H1 depletion did not significantly affect the recruitment of known structural or functional chromosomal components such as condensins or chromokinesins, suggesting that the loss of H1 affects chromosome architecture directly. Thus, our results indicate that linker histone H1 plays an important role in the structure and function of vertebrate chromosomes in mitosis

Mindlessness and the Law

No less an authority than Milton Friedman has argued that improving the realism of assumptions in economic theory, although hardly essential to establishing the absolute validity of the theory (purely an empirical question), may offer several benefits. First, a “restructuring” (to use Posner\u27s term) of an assumption may help explain divergences between predicted and observed results. Second, an explanation of why a seemingly unrealistic assumption does not destroy the predictive value of a theory may strengthen the theory by connecting it to “a more general theory that applies to a wider variety of phenomena . . . and has failed to be contradicted under a wider variety of circumstances.” Also, a different and more “realistic” explanation of an assumption may facilitate an indirect test of the hypothesis by its implications. We hope this Article will make economic theory more attractive in all three of the above ways and will constitute an effective response to critics of law and economics. Part I of this Article reviews several behavior-based criticisms of economic analysis of law. In order to answer the criticisms discussed in Part I, we have included an introduction to psychological “script theory” in Part II. A brief description of the theory might have sufficed, but we hope that a fuller exposition, including some reference to empirical data, may more effectively provoke investigation and application to legal scholarship. Thus, in Part II we examine relevant models of human decisionmaking developed recently in the fields of psychology and social science, and these models are based on evidence that unconscious information gathering and assessment play an important role in human decisionmaking. Part III will use the models to suggest why economists\u27 seemingly unrealistic notions concerning human behavior need not blunt the value of their insight into the efficient deterrence rationale of the tort system. Section A of Part III accepts the validity of the handful of empirical studies demonstrating that people react to legal rules in the manner predicted by law and economics. We use the models described in Part II to suggest the mechanism by which those rules affect behavior. We conclude by defusing potential attacks that could be made on our explanation by researchers who demonstrate the existence of “cognitive illusions.” In Section B, we relax the assumptions underlying the economic model and consider Robert Ellickson\u27s claim that legal rules are frequently a less important determinant of behavior than cultural norms. We conclude that even if the assumptions underlying the economic model are faulty, law and economics remains a powerful tool for explaining the common law

Transaction Costs and Patent Reform

This article considers current proposals for patent law reform in light of a simple theory about intellectual property law: In a world without transactions costs, the assignment of property rights is not necessary to stimulate the optimal production of creative goods. Because potential users of inventions could contract for their creation, a compelling justification for granting property rights in these intangibles is the reduction of real-world transaction and information costs that hinder, or make impossible, contract formation between users and creators. Proposals for patent law reform, therefore, should be evaluated by whether a change in legal rights, or in the regulatory process increases or lowers these costs

The condensin complex is required for proper spindle assembly and chromosome segregation in Xenopus egg extracts.

Chromosome condensation is required for the physical resolution and segregation of sister chromatids during cell division, but the precise role of higher order chromatin structure in mitotic chromosome functions is unclear. Here, we address the role of the major condensation machinery, the condensin complex, in spindle assembly and function in Xenopus laevis egg extracts. Immunodepletion of condensin inhibited microtubule growth and organization around chromosomes, reducing the percentage of sperm nuclei capable of forming spindles, and causing dramatic defects in anaphase chromosome segregation. Although the motor CENP-E was recruited to kinetochores pulled poleward during anaphase, the disorganized chromosome mass was not resolved. Inhibition of condensin function during anaphase also inhibited chromosome segregation, indicating its continuous requirement. Spindle assembly around DNA-coated beads in the absence of kinetochores was also impaired upon condensin inhibition. These results support an important role for condensin in establishing chromosomal architecture necessary for proper spindle assembly and chromosome segregation

Testing the Over- and Under-Exploitation Hypothesis: Bestselling Musical Compositions (1913-32) and Their Use in Cinema (1968-2007)

Some economists assert that as valuable works transition from copyrighted status and fall into the public domain they will be underexploited and their value dissipated. Others insist instead that without an owner to control their use, valuable public domain works will be overexploited or otherwise debased. This study of the most valuable musical compositions from 1913-32 demonstrates that neither hypothesis is true as it applies to the exploitation of songs in movies from 1968-2007. When compositions fall into the public domain, they are just as likely to be exploited in movies, suggesting no under-exploitation. And the rate of exploitation of these public domain songs is no greater than that of copyrighted songs, indicating no congestion externality. The absence of market failure is likely due to producer and consumer self-regulation

Mindlessness and Nondurable Precautions

Assuming initially that negligence law does not make the distinction between durable and nondurable precautions, this Article will first explain in economic terms why the failure of courts to take into account the cost of remembering may nonetheless be efficient. A substantial body of research on the phenomenon of mindless decisionmaking ( scripting ) suggests that most remembering is automatic--a nonconscious response to frequently encountered patterns of stimuli. Script theory suggests that once the behavioral script is in place, an automatic response operates at a very low cost. If so, the failure of courts to account for the cost of remembering would not be so startling. An examination of the case law in Part II of this Article, however, reveals that courts do consider the cost of remembering. The common law recognizes that not all forgetfulness is negligent and authorizes juries to find that reasonable people can forget. A close look at the case law reveals the sensitivity of the common law to the vagaries of human memory and the phenomenon of mindless decisionmaking. Nonetheless, Part III suggests that a focus on nondurable precautions may help explain the existence of negligence cases. Although the case law articulates efficient rules governing negligence in cases of forgetting, high information costs of the jury system may explain why negligence cases persists