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LET-99 functions in the astral furrowing pathway, where it is required for myosin enrichment in the contractile ring.
The anaphase spindle determines the position of the cytokinesis furrow, such that the contractile ring assembles in an equatorial zone between the two spindle poles. Contractile ring formation is mediated by RhoA activation at the equator by the centralspindlin complex and midzone microtubules. Astral microtubules also inhibit RhoA accumulation at the poles. In the Caenorhabditis elegans one-cell embryo, the astral microtubule-dependent pathway requires anillin, NOP-1, and LET-99. LET-99 is well characterized for generating the asymmetric cortical localization of the Gα-dependent force-generating complex that positions the spindle during asymmetric division. However, whether the role of LET-99 in cytokinesis is specific to asymmetric division and whether it acts through Gα to promote furrowing are unclear. Here we show that LET-99 contributes to furrowing in both asymmetrically and symmetrically dividing cells, independent of its function in spindle positioning and Gα regulation. LET-99 acts in a pathway parallel to anillin and is required for myosin enrichment into the contractile ring. These and other results suggest a positive feedback model in which LET-99 localizes to the presumptive cleavage furrow in response to the spindle and myosin. Once positioned there, LET-99 enhances myosin accumulation to promote furrowing in both symmetrically and asymmetrically dividing cells
CEO Pay and Firm Performance: Dynamics, Asymmetries, and Alternative Performance Measures
This study explores the dynamic structure of the pay-for- performance relationship in CEO compensation and quantifies the effect of introducing a more complex model of firm financial performance on the estimated performance sensitivity of executive pay. The results suggest that current compensation responds to past performance outcomes, but that the effect decays considerably within two years. This contrasts sharply with models of infinitely persistent performance effects implicitly assumed in much of the empirical compensation literature. We find that both accounting and market performance measures influence compensation and that the salary and bonus component of pay as well as total compensation have become more sensitive to firm financial performance over the past two decades. There is no evidence that boards fail to penalize CEOs for poor financial performance or reward them disproportionately well for good performance. Finally, the data suggest that boards may discount extreme performance outcomes -both high and low - relative to performance that lies within some `normal' band in setting compensation.
Leak test system
System for quantitative determination of leak rates in large pressurized compartments is described. Method uses pressure reference cylinder placed in thermal contact with internal environment of compartment. Construction of equipment and details of operational procedure are reported. Illustration of equipment is included
The Diffusion of New Technologies: Evidence From the Electric Utility Industry
This paper investigates the effect of firm size and ownership structure on technology adoption decisions, using data on the electric utility industry. We argue that traditional models of technology diffusion are subject to sample selectivity biases that may overstate the effect of firm size on adoption probabilities. By extending conventional hazard rate models to use information on both adoption and non-adoption decisions, we differentiate between firms' opportunities for adoption and their underlying adoption propensities. The results suggest that large firms and investor-owned electric utilities are likely to adopt new technologies earlier than their smaller and publicly-owned counterparts. Moreover, the selection biases from conventional statistical models can lead one to overstate size effects by a factor of two and to understate ownership structure and factor cost effects by two to four times.
Developing Cost Effective Methods for Estimating Household Income and Nutrient Intake Adequacy
Community/Rural/Urban Development, Food Consumption/Nutrition/Food Safety, Downloads July 2008 - July 2009: 6,
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Does Competition Reduce Costs? Assessing the Impact of Regulatory Restructuring on U.S. Electric Generation Efficiency
This paper explores the empirical effects of competition on technical efficiency in the context of electricity industry restructuring. Restructuring programs adopted by many U.S. states made utilities residual claimants to cost savings and increased their exposure to competitive markets. We estimate the impact of these changes on annual generating plant-level input demand for non-fuel operating expenses, the number of employees and fuel use. We find that municipally-owned plants, whose owners were for the most part unaffected by restructuring, experienced the smallest efficiency gains over the past decade. Investor-owned utility plants in states that restructured their wholesale electricity markets had the largest reductions in nonfuel operating expenses and employment, while investor-owned plants in nonrestructuring states fell between these extremes. The analysis also highlights the substantive importance of treating the simultaneity of input and output decisions, which we do through an instrumental variables approach
Competition and Price Dispersion in the U.S. Airline Industry
This papers analyzes dispersion in the prices that an airline charges to different customers on the same route. Such variation in airlines fares is substantial: the expected absolute difference in fares between two of an airline's passengers on a route averages thirty-six percent of the airline's average ticket price on the route. The pattern of price dispersion that we find does not seem to be explained solely by cost differences. Dispersion is higher on more competitive routes, possibly reflecting a pattern of discrimination against customers who are less willing to switch to alternative flights or airlines. We argue that the data support an explanation based on theories of price discrimination in monopolistically competitive industries.
Airborne measurement of atmospheric turbulence
A system capable of making measurements of fluctuating atmospheric density is described. Spatial scales required in assessing the quality of coherent radiation propagation are discussed. The special sensors, aircraft installation, data reduction procedures, and other special requirements necessary to obtain meaningful atmospheric turbulence data are also described. The spectral distribution of density fluctuation are presented
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