Within-Firm Pay Inequality

Financial regulators and investors have expressed concerns about high pay inequality within firms. Using a proprietary data set of public and private firms, this paper shows that firms with higher pay inequality—relative wage differentials between top- and bottom-level jobs—are larger and have higher valuations and stronger operating performance. Moreover, firms with higher pay inequality exhibit larger equity returns and greater earnings surprises, suggesting that pay inequality is not fully priced by the market. Our results support the notion that differences in pay inequality across firms are a reflection of differences in managerial talent

Undersea navigation of a glider UUV using an acoustic communications network

The US Navy is developing Seaweb undersea acoustic networking technology to enable distributed autonomous ocean sensors. An Unmanned Undersea Vehicle (UUV) can operate as a mobile node among the grid in the conduct of its own mission, using the fixed nodes as navigation reference points. The fixed grid provides a cellular communications infrastructure for command & control and data telemetry. In turn, the UUV can support the fixed grid by physically redistributing large quantities of data throughout the network or for breaching the sea surface and acting as a mobile gateway node, communicating via satellite to a command center ashore. Assimilating UUVs as network nodes significantly enhances undersea network capability, expanding the available concepts of operations. This thesis concerns the use of the fixed undersea network as a means to track the UUV and anticipates routine operations of mobile nodes in the context of fixed grids. This work is also a fundamental step toward advanced operations of fully mobile networks in the form of collaborative swarms.http://archive.org/details/undersenavigatio109452080Approved for public release; distribution is unlimited

Asymmetric Hillslope Erosion Following Wildfire in Fourmile Canyon, Colorado

Infrequent, high-magnitude events cause a disproportionate amount of sediment transport on steep hillslopes, but few quantitative data are available that capture these processes. Here we study the influence of wildfire and hillslope aspect on soil erosion in Fourmile Canyon, Colorado. This region experienced the Fourmile Fire of 2010, strong summer convective storms in 2011 and 2012, and extreme flooding in September 2013. We sampled soils shortly after these events and use fallout radionuclides to trace erosion on polar- and equatorial-facing burned slopes and on a polar-facing unburned slope. Because these radionuclides are concentrated in the upper decimeter of soil, soil inventories are sensitive to erosion by surface runoff. The polar-facing burned slope had significantly lower cesium-137 (137Cs) and lead-210 (210Pb) inventories (p \u3c 0.05) than either the polar-facing unburned slope or equatorial-facing burned slope. Local slope magnitude does not appear to control the erosional response to wildfire, as relatively gently sloping (~20%) polar-facing positions were severely eroded in the most intensively burned area. Field evidence and soil profile analyses indicate up to 4 cm of local soil erosion on the polar-facing burned slope, but radionuclide mass balance indicates that much of this was trapped nearby. Using a 137Cs-based erosion model, we find that the burned polar-facing slope had a net mean sediment loss of 2 mm (~1 kg m−2) over a one to three year period, which is one to two orders of magnitude higher than longer-term erosion rates reported for this region. In this part of the Colorado Front Range, strong hillslope asymmetry controls soil moisture and vegetation; polar-facing slopes support significantly denser pine and fir stands, which fuels more intense wildfires. We conclude that polar-facing slopes experience the most severe surface erosion following wildfires in this region, indicating that landscape-scale aridity can control the geomorphic response of hillslopes to wildfires. Copyright © 2018 John Wiley & Sons, Ltd

Is the Riemann zeta function in a short interval a 1-RSB spin glass ?

Fyodorov, Hiary & Keating established an intriguing connection between the maxima of log-correlated processes and the ones of the Riemann zeta function on a short interval of the critical line. In particular, they suggest that the analogue of the free energy of the Riemann zeta function is identical to the one of the Random Energy Model in spin glasses. In this paper, the connection between spin glasses and the Riemann zeta function is explored further. We study a random model of the Riemann zeta function and show that its two-overlap distribution corresponds to the one of a one-step replica symmetry breaking (1-RSB) spin glass. This provides evidence that the local maxima of the zeta function are strongly clustered.Comment: 20 pages, 1 figure, Minor corrections, References update

On landmark selection and sampling in high-dimensional data analysis

In recent years, the spectral analysis of appropriately defined kernel matrices has emerged as a principled way to extract the low-dimensional structure often prevalent in high-dimensional data. Here we provide an introduction to spectral methods for linear and nonlinear dimension reduction, emphasizing ways to overcome the computational limitations currently faced by practitioners with massive datasets. In particular, a data subsampling or landmark selection process is often employed to construct a kernel based on partial information, followed by an approximate spectral analysis termed the Nystrom extension. We provide a quantitative framework to analyse this procedure, and use it to demonstrate algorithmic performance bounds on a range of practical approaches designed to optimize the landmark selection process. We compare the practical implications of these bounds by way of real-world examples drawn from the field of computer vision, whereby low-dimensional manifold structure is shown to emerge from high-dimensional video data streams.Comment: 18 pages, 6 figures, submitted for publicatio

Locally Delivered Salicylic Acid From a Poly(anhydride-ester): Impact on Diabetic Bone Regeneration

Diabetes mellitus (DM) involves metabolic changes that can impair bone repair, including a prolonged inflammatory response. A salicylic acid-based poly(anhydride-ester) (SA-PAE) provides controlled and sustained release of salicylic acid (SA) that locally resolves inflammation. This study investigates the effect of polymer-controlled SA release on bone regeneration in diabetic rats where enhanced inflammation is expected. Fifty-six Sprague–Dawley rats were randomly assigned to two groups: diabetic group induced by streptozotocin (STZ) injection or normoglycemic controls injected with citrate buffer alone. Three weeks after hyperglycemia development or vehicle injection, 5 mm critical sized defects were created at the rat mandibular angle and treated with SA-PAE/bone graft mixture or bone graft alone. Rats were euthanized 4 and 12 weeks after surgery, then bone fill percentage in the defect region was assessed by micro-computed tomography (CT) and histomorphometry. It was observed that bone fill increased significantly at 4 and 12 weeks in SA-PAE/bone graft-treated diabetic rats compared to diabetic rats receiving bone graft alone. Accelerated bone formation in normoglycemic rats caused by SA-PAE/bone graft treatment was observed at 4 weeks but not at 12 weeks. This study shows that treatment with SA-PAE enhances bone regeneration in diabetic rats and accelerates bone regeneration in normoglycemic animals