Search

Wave energy propagating into the Antarctic marginal ice zone affects the quality and extent of the sea ice, and wave propagation is therefore an important factor for understanding and predicting changes in sea ice cover. Sea ice is notoriously hard to model and in-situ observations of wave activity in the Antarctic marginal ice zone are scarce, due to the extreme conditions of the region. Here, we provide new in-situ data from two drifting Surface Wave Instrument Float with Tracking (SWIFT) buoys deployed in the Weddell Sea in the austral winter and spring in 2019. The buoy location ranges from open water to more than 200 km into the sea ice. We estimate the attenuation of swell with wave periods 8-18 s, and find an attenuation coefficient α = 4 · 10 to 7 · 10 m in spring, and approximately five-fold larger in winter. The attenuation coefficients show a power law frequency dependence, with power coefficient 3.3 in spring and 4 in winter. The in-situ data also shows a change in wave direction, where wave direction tends to be more perpendicular to the ice edge farther into the sea ice. A possible explanation for this might be a change in the dispersion relation caused by changing sea ice composition. These observations can help shed further light on the influence of sea ice on waves propagating into the Marginal Ice Zone, aiding development of coupled wave-sea ice models.

We test predictions that managers issuing voluntary capex guidance learn from analyst feedback and that this learning enhances investment efficiency and firm performance. Our findings are consistent with these predictions. First, we find that managers’ capex adjustments and capex guidance revisions relate positively with analyst feedback measured by differences between postguidance analyst capex forecasts and managerial capex guidance. Second, changes in investment efficiency relate positively with analyst feedback. Third, subsequent firm financial performance relates positively with the predicted values of both managers’ capex adjustments and capex guidance revisions. These findings extend prior evidence regarding sources of managerial learning and investment efficiency and help to explain the active issuance of voluntary guidance by managers in settings where, as for capex guidance, the potential for managerial learning from related share price effects is limited, as we also explain. This paper was accepted by Brian Bushee, accounting.

An analysis of the geometry and structure of centre vortices in the presence of dynamical fermions is performed. A variety of metrics are used to measure the matrix structure of the vortex-modified gauge fields. Visualisations of centre vortices are presented and percolating clusters are identified. The size of secondary vortex clusters is analysed, with substantial differences observed between the pure Yang-Mills and dynamical fermion case. Vortex fields are represented as directed graphs, with branching points acting as the vertices. This representation leads to a novel picture of vortex branching as a binomial process. These results elucidate the change in the centre vortex vacuum induced by the introduction of dynamical fermions., 18 pages, 22 figures

For the first time, center vortices are identified on SU(3) lattice ensembles that include dynamical fermions. Using a variational method, the static quark potential is calculated on untouched, vortex-removed, and vortex-only fields. Two dynamical ensembles and one pure gauge ensemble are studied, allowing for an exploration of the impact of dynamical fermions on the center-vortex vacuum. Novel modifications to the standard Coulomb term are introduced to describe the long range behavior of the vortex-removed potential. These modifications remove a source of systematic error in the fitted string tension on the original ensembles. Our pure Yang-Mills result is consistent with previous studies, where projected center-vortex fields only reproduce approximately two thirds of the string tension. Remarkably, we find that the vortex-only fields on both dynamical lattices are able to fully reproduce the respective untouched string tensions.

The impact of SU(3) center vortices on the Landau-gauge gluon propagator is calculated in the presence of dynamical fermions and compared to the pure Yang-Mills case. The presence of dynamical fermions is found to alter the behavior of the center vortex propagator when compared to the established pure-gauge result. The gluon spectral representation is also explored from the center vortex perspective, where center vortices are shown to exhibit clear signs of positivity violation, which is an indicator of confinement. Vortex removal subsequently restores positivity, demonstrating the crucial role center vortices play in the confinement of gluons.

Antarctic sea ice is prevalently seen as a major player in the climate system, but it is also an important factor in polar maritime safety. Remote sensing and forecasting of Southern Ocean sea ice ...

Water mass transformation in the Southern Ocean is vital for driving the large-scale overturning circulation, which transports heat from the surface to the ocean interior. Using profiling gliders, this study investigates the role of summertime buoyancy forcing and wind-driven processes on the intraseasonal (1–10 days) mixed layer thermohaline variability in three Southern Ocean regions southwest of Africa important for water mass transformation—the Subantarctic Zone (SAZ), Polar Frontal Zone (PFZ), and Marginal Ice Zone (MIZ). At intraseasonal time scales, heat flux was shown as the main driver of buoyancy gain in all regions. In the SAZ and MIZ, shallow mixed layers and strong stratification enhanced mixed layer buoyancy gain by trapping incoming heat, while buoyancy loss resulted primarily from the entrainment of cold, salty water from below. In the PFZ, rapid mixing linked to Southern Ocean storms set persistently deep mixed layers and suppressed mixed layer intraseasonal thermohaline variability. In the polar regions, lateral stirring of meltwater from seasonal sea-ice melt dominated daily mixed layer salinity variability. We propose that these meltwater fronts are advected to the PFZ during late summer, indicating the potential for seasonal sea-ice freshwater to impact a region where the upwelling limb of overturning circulation reaches the surface. This study reveals a regional dependence of how the mixed layer thermohaline properties respond to small spatiotemporal processes, emphasizing the importance of surface forcing occurring between 1 and 10 days on the mixed layer water mass transformation in the Southern Ocean.

Water mass transformation in the Southern Ocean is vital for closing the large-scale overturning circulation, altering the thermohaline characteristics of upwelled Circumpolar Deep Water before returning to the ocean interior. Using profiling gliders, this study investigates how buoyancy forcing and wind-driven processes lead to intraseasonal (1-10 days) variability of the mixed layer temperature and salinity in three distinct locations associated with different Southern Ocean regions important for water mass transformation - the Subantarctic Zone (SAZ, 43°S), Polar Frontal Zone (PFZ, 54°S) and Marginal Ice Zone (MIZ, 60°S). Surface heat fluxes drive the summertime mixed layer buoyancy gain in all regions, particularly evident in the SAZ and MIZ, where shallow mixed layers and strong stratification further enhance mixed layer warming. In the SAZ and MIZ, the entrainment of denser water from below is the primary mechanism for reducing buoyancy gain. In the PFZ, turbulent mixing by mid-latitude storms result in consistently deep mixed layers and suppressed mixed layer thermohaline variability. Intraseasonal mixed layer salinity variability in the polar regions (PFZ and MIZ) is dominated by the lateral stirring of meltwater from seasonal sea ice melt. This is evident from early summer in the MIZ, while in the PFZ, meltwater fronts are proposed to be dominant during late summer, indicating the potential for seasonal sea ice freshwater to impact a region where the upwelling limb of overturning circulation reaches the surface. This study reveals a regional dependence of mixed layer thermohaline properties to small spatio-temporal processes, which suggests a similar regional dependence to surface water mass transformation in the Southern Ocean.

The Southern Ocean is fundamental for our climate, accounting for 75% of the total oceanic heat uptake and absorbing 93% of excess heat arising from global warming. However, direct observations of air-sea heat fluxes are still scarce, particularly at small spatial and temporal scales. This study investigates the effect of fine-scale frontal activity (0.1 km–10 km) and sampling bias on measured turbulent heat fluxes in the Southern Ocean using high-resolution hydrographic and meteorological data collected by three autonomous surface vehicles (Saildrones) during their 2019 circumnavigation of Antarctica. We show that the uncertainty in observed air-sea heat fluxes increases with reduced sampling frequency. To have a 90% chance of capturing the mean turbulent heat flux within ±1 Wm2, the required sampling resolution is less than 30 km in summer and less than 10 km in winter. Surface temperature-driven density fronts were found to be numerous throughout the in situ datasets and ranged in length-scales from sub-kilometer to mesoscale (order of 0.1 km–100 km). The magnitude and variability of the turbulent heat flux gradient over these fronts tends to decrease with increasing frontal length, suggesting a strong coupling between heat fluxes and front size, thereby underscoring the need to capture fine-scale oceanographic features to better resolve air-sea fluxes of heat.

This study examines the relation between accounting conservatism and bankruptcy risk using a large sample of U.S listed firms. We present evidence that unconditional and conditional conservatism generally are negatively associated with subsequent bankruptcy risk by creating cushions for bad times and reducing information asymmetry between borrower firms and debtholders. We identify two channels for the observed associations: Enhancing cash holdings and constraining earnings management. Using a two-stage analysis approach and using Sarbanes-Oxley Act (SOX) enactment in 2002 as exogenous shocks, we show that accounting conservatism does have a mitigating effect on bankruptcy risk.

The Skagerrak and Kattegat are a narrow and shallow channel separating the North Sea and Baltic Sea. This highly dynamic area plays a key role in transforming water masses which flow into and oxygenate deep regions of the Baltic. This site is also a region of important carbon export, through advection down into and through the Norwegian Trench. This rich and productive ecosystem is strained by intensive human activity and shows strong coupling between biological and physical processes at a range of scales. We present data from a new autonomous observatory funded by the Voice of the Ocean Foundation. We compare data obtained from two underwater gliders and autonomous surface vehicles with that collected through regional monitoring programmes. Empirical variograms highlight the strong coupling between biological and physical parameters and the prevalence of small-scale processes not usually resolved in this region. We also present event-scale case studies showing variability in the coastal current and small scale export events. Finally, we outline the technical infrastructure and innovations of the Voice of the Ocean observatories and how to access its open data.

The role of the Southern Ocean in the global heat and carbon cycle is fundamental towards our climate, but observational data to quantify air-sea fluxes, such as surface heat fluxes, are still scarce. In order to investigate the effects of fine- scale oceanic fronts (0.1 km–10 km) on air-sea fluxes in the Southern Ocean, high-resolution hydrographic and meteorological data collected by three un-crewed surface vehicles (Saildrones) during their first Circumnavigation of Antarctica in 2019 was assessed. Comparisons of key variables from the in situ Saildrones datasets with those from ERA5 and a stationary mooring show good agreement. Temperature-driven density fronts were detected in the Saildrone data and their impact on the turbulent heat flux was quantified during steady atmospheric conditions. Over 2000 surface ocean temperature dominated density fronts were detected at length-scales (i.e. front width) ranging from sub-kilometer to mesoscale (order of 0.1 km–100 km). Temperature-driven density fronts with a length scale (as seen from the Saildrones perspective ) smaller than 1 km contributed 75% and 51% of the sensible and latent heat flux changes, respectively. The direct link between the fronts and the impact on the heat fluxes decreases sharply when the front length increases. This suggests that smaller (submesoscale) fronts have a larger impact on heat flux variability than larger (balanced) fronts . The parametrization of these fine-scale ocean-atmospheric processes in global climate models could lead to more accurate representations of the heat flux variability both at local and global scale.

Funding: This work is funded by the UK Natural Environment Research Council under the iSTAR Programme through grants NE/J005703/1 (K.J.H., D.P.S., B.G.M.W.); European Research Council (under H2020-EU.1.1.) under research grant COMPASS (Climate-relevant Ocean Measurements and Processes on the Antarctic continental Shelf and Slope, grant agreement ID: 741120, K.J.H., Y.Z.); National Science Foundation Division of Polar Programs and Natural Environment Research Council under the research grant TARSAN (Thwaites-Amundsen Regional Survey and Network, NSF PLR 1738992 and NE/S006419/1, K.J.H.).Y.Z. is supported by China Scholarship Council and University of East Anglia. L.C.B. is supported by a Wallenberg Academy Fellowship (WAF 2015.0186) and Swedish Research Council grant (VR2019-04400) of S. Swart. Determining the injection of glacial meltwater into the polar oceans is crucial for quantifying the response of the climate system to ice sheet mass loss. However, meltwater is poorly observed and its pathways poorly known, especially in winter. Here we present winter meltwater distribution in the eastern Amundsen Sea near Pine Island Glacier, revealing a highly variable meltwater distribution with two meltwater-rich layers in the upper 250 m and at around 450 m, connected by scattered meltwater-rich columns. We show that the hydrographic signature of meltwater is clearest in winter, when its presence can be unambiguously mapped throughout the water column. We argue that the buoyant meltwater provides near-surface nutrient that enhances productivity and heat that helps maintain polynyas, close to ice shelves across the Amundsen Sea. Therefore, although the processes determining the distribution of meltwater are challenging, they are important to represent in Earth system models. Publisher PDF

Submesoscale flows in the ocean are energetic motions, O(1–10 km), that influence stratification and the distributions of properties, such as heat and carbon. They are believed to play an important role in sea‐ice‐impacted oceans by modulating air‐sea‐ice fluxes and sea‐ice extent. The intensity of these flows and their response to wind forcing are unobserved in the sea‐ice regions of the Southern Ocean. We present the first submesoscale‐resolving observations in the Antarctic marginal ice zone (MIZ) collected by surface and underwater autonomous vehicles, for >3 months in austral summer. We observe salinity‐dominated lateral density fronts occurring at sub‐kilometer scales. Surface winds are shown to modify the magnitude of the mixed‐layer density fronts, revealing strongly coupled atmosphere‐ocean processes. We posture that these wind‐front interactions occur as a continuous interplay between front slumping and vertical mixing, which leads to the dispersion of submesoscale fronts. Such processes are expected to be ubiquitous in the Southern Ocean MIZ.

SYNOPSIS Chinese firms listing in the U.S. via reverse mergers (CRMs) have dominated prior media, regulator, and research attention. Yet CRMs have effectively ceased, leaving Chinese firms listing via initial public offerings (CIPOs) as the relevant remaining class of Chinese firms listing on U.S. exchanges. This study documents salient differences between CIPOs, CRMs, and U.S.-domiciled U.S.-listed firms by examining Sarbanes-Oxley Act Section 302 and 404(b) ineffective internal control (IIC) and related disclosures that underlie financial reporting quality, with three main sets of findings. First, both CIPOs and CRMs are more likely to report IICs than U.S.-domiciled counterparts. Second, both CIPOs and CRMs are more likely to under-report IICs than U.S.-domiciled counterparts (CIPO for only 302 disclosures). Third, CIPOs are both less likely to report and less likely to under-report IICs than CRMs. These findings clarify and recast prior characterizations of the internal controls underlying the reporting quality of Chinese U.S.-listed firms. JEL Classifications: G18; G34; G38; M41; M42; M48. Data Availability: All data are available from public sources.

Spatiotemporal (ST) analytics applied to major data sources such as the World Bank and World Health Organization has shown tremendous value in shedding light on the evolution of cultural, health, economic, and geopolitical landscapes on a global level. WSTAMP engages this opportunity by situating analysts, data, and analytics together within a visually rich and computationally rigorous online analysis environment. Since introducing WSTAMP at the First International Workshop on Spatiotemporal Computing, several transformative advances have occurred. Collaboration with human computer interaction experts led to a complete interface redesign that deeply immerses the analyst within a ST context, significantly increases visual and textual content, provides navigational crosswalks for attribute discovery, substantially reduce mouse and keyboard actions, and supports user data uploads. Secondly, the database has been expanded to include over 16,000 attributes, 50 years of time, and 200+ nation states and redesigned to support non-annual, non-national, city, and interaction data. Finally, two new analytics are implemented for analyzing large portfolios of multi-attribute data and measuring the behavioral stability of regions along different dimensions. These advances required substantial new approaches in design, algorithmic innovations, and increased computational efficiency. We report on these advances and inform how others may freely access the tool.

This work was supported by funding from the UK Natural Environment Research Council's iSTAR Program through grants NE/J005703, NE/J005649/1 and NE/J005770/1. The Amundsen Sea is a key region of Antarctica where ocean, atmosphere, sea ice and ice sheet interact. For much of Antarctica, the relatively warm ocean water in the open Southern Ocean (a few degrees above freezing) is unable to reach the continental shelf in large volumes under current climate conditions. In the Amundsen Sea, however, warm water penetrates onto the continental shelf and provides heat that can melt the underside of the floating ice shelves. Here we discuss how the role of the ocean has come under increased scrutiny in recent years, because ocean heat fluxes have been implicated in the thinning of the ice shelves. We present observations from the Amundsen Sea in 2014 and discuss their implications, highlighting aspects where our understanding is still incomplete. Publisher PDF

Pine Island Ice Shelf, in the Amundsen Sea, is losing mass due to increased heat transport by warm ocean water penetrating beneath the ice shelf and causing basal melt. Tracing this warm deep water and the resulting glacial meltwater can identify changes in melt rate and the regions most affected by the increased input of this freshwater. Here, optimum multi‐parameter analysis is used to deduce glacial meltwater fractions from independent water mass characteristics (standard hydrographic observations, noble gases and oxygen isotopes), collected during a ship‐based campaign in the eastern Amundsen Sea in February‐March 2014. Noble gases (neon, argon, krypton and xenon) and oxygen isotopes are used to trace the glacial melt and meteoric water found in seawater and we demonstrate how their signatures can be used to rectify the hydrographic trace of glacial meltwater, which provides a much higher resolution picture. The presence of glacial meltwater is shown to mask the Winter Water properties, resulting in differences between the water mass analyses of up to 4 g kg−1 glacial meltwater content. This discrepancy can be accounted for by redefining the ”pure” Winter Water endpoint in the hydrographic glacial meltwater calculation. The corrected glacial meltwater content values show a persistent signature between 150 ‐ 400 m of the water column across all of the sample locations (up to 535 km from Pine Island Ice Shelf), with increased concentration towards the west along the coastline. It also shows, for the first time, the signature of glacial meltwater flowing off‐shelf in the eastern channel.

The structure of centre vortices in SU(3) gauge-field configurations is examined through modern visualization techniques. Centre vortices are identified through gauge transformations maximizing the centre of the gauge group. Focusing on the thin vortices identified by Wilson loops having a non-trivial centre phase, the vortex structure is illustrated through renderings of oriented spatial plaquettes. Time oriented plaquettes are illustrated by identifying spatial links associated with these non-trivial plaquettes. The results illustrate an important role for the branching of SU(3) centre vortices, possibly through monopole anti-monopole dynamics. Of particular interest is the correlation of the vortex structure and the topological-charge structure of the gauge fields, vital to dynamical chiral symmetry breaking and its associated mass generation. Singular points, where the projected vortex structure contains non-trivial centre phases in associated plaquettes spanning all four dimensions, are observed within the regions of nontrivial topological charge density calculated on the original Monte-Carlo generated configurations. The results provide new insights into the role of centre vortices in underpinning non-trivial topology in gauge fields. They reveal how the removal of centre-vortices necessarily destroys non-trivial topology and destabilizes would-be instantons under smoothing algorithms. The observed correlations further strengthen the idea that centre vortices are the seeds of dynamical chiral symmetry breaking., 7 pages, 5 figures, 3D figures require Adobe Reader 9 or later, acroread version 9.4.1 for Linux. To appear in the proceedings of Lattice 2018, the 36th International Symposium on Lattice Field Theory, Michigan State University, USA, 22-28 July, 2018

Water utility managers play potentially important roles in current and future transitions toward more adaptive and sustainable approaches to water management. We report the results of qualitative interviews and focus groups designed to explore the perspectives of 22 water utility managers in the United States regarding pressures, challenges, and opportunities facing their organizations and communities. Overall, the study participants characterized their jobs as requiring a delicate balance between innovation and reliability, with no room for error in delivering abundant, clean water, but opportunities for creative problem-solving and forward planning. They demonstrated capacity for embracing changes that benefit the longer term future while imposing short-term costs on their own organizations. Coding of transcripts generated 17 major themes (11 problem categories and six solution categories), which overlap meaningfully with results of previous research on resilience, adaptability, and transformability of social-ecological systems. Overlapping themes include social learning and development of social capital through various forms of collaboration, communication, and citizen and stakeholder engagement, as well as capacity for innovation and sufficient authority to make decisions based on system needs without undue political interference or burdensome adherence to rigid rule structures.

The structure of the SU(3) gauge-field vacuum is explored through visualisations of centre vortices and topological charge density. Stereoscopic visualisations highlight interesting features of the vortex vacuum, especially the frequency with which singular points appear and the important connection between branching points and topological charge. This work demonstrates how visualisations of the QCD ground-state fields can reveal new perspectives of centre-vortex structure., 7 pages, 5 figures. In the proceedings of CHEP 2019 - 24rd International Conference on Computing in High Energy and Nuclear Physics, Adelaide, Australia, 4-8 November 2019

The centre vortex structure of the vacuum is visualised through the use of novel 3D visualisation techniques. These visualisations allow for a hands-on examination of the centre-vortex matter present in the QCD vacuum, and highlights some of the key features of the centre-vortex model. The connection between topological charge and singular points is also explored. This work highlights the useful role visualisations play in the exploration of the QCD vacuum., Comment: 6 pages, 9 figures. In the proceedings of CHEP 2019 - 24rd International Conference on Computing in High Energy and Nuclear Physics, Adelaide, Australia, 4-8 November 2019

The impact of $SU(3)$ centre vortices on the gluon propagator in Landau gauge is investigated on original, vortex-removed and vortex-only lattice gauge field configurations. Vortex identification is found to partition the gluon propagator into short range strength on the vortex removed configurations and long range strength on the vortex only configurations. The effect of smoothing vortex-only configurations is also studied, and a regime for recovering the form of the smoothed original propagator from vortex-only configurations is introduced. The results reinforce the significance of centre vortices in a fundamental understanding of QCD vacuum structure., 9 pages, 9 figures, 1 table, version accepted for publication

While it has become more commonplace as an environmental management strategy, few empirical studies have evaluated the environmental performance of collaborative governance regimes. Using w...

Pine Island Ice Shelf, in the Amundsen Sea, is losing mass because of warm ocean waters melting the ice from below. Tracing meltwater pathways from ice shelves is important for identifying the regions most affected by the increased input of this water type. Here, optimum multiparameter analysis is used to deduce glacial meltwater fractions from water mass characteristics (temperature, salinity, and dissolved oxygen concentrations), collected during a ship-based campaign in the eastern Amundsen Sea in February–March 2014. Using a one-dimensional ocean model, processes such as variability in the characteristics of the source water masses on shelf and biological productivity/respiration are shown to affect the calculated apparent meltwater fractions. These processes can result in a false meltwater signature, creating misleading apparent glacial meltwater pathways. An alternative glacial meltwater calculation is suggested, using a pseudo–Circumpolar Deep Water endpoint and using an artificial increase in uncertainty of the dissolved oxygen measurements. The pseudo–Circumpolar Deep Water characteristics are affected by the under ice shelf bathymetry. The glacial meltwater fractions reveal a pathway for 2014 meltwater leading to the west of Pine Island Ice Shelf, along the coastline.

Using a unique dataset of foreign and domestic IPOs listings in the US from 1990 to 2012, we study how foreignness affects IPO liquidity. We find that foreign IPOs enjoy higher liquidity than IPOs in their home countries, but do not fully gain the same liquidity benefits as for IPOs of domestic US issuers. In contrast to prior evidence for mature cross-listed firms, we show that liquidity differentials between foreign and domestic IPOs in the US are determined by information asymmetry related to foreignness rather than to home-country institutional environment characteristics. Thus, our results extend prior findings to reveal salient differences in liquidity and liquidity determinants between IPOs offerings by foreign and domestic firms in the US.

We present evidence that managerial responses to voluntary clawback adoptions depend on compensation incentives that can induce capital investment mix shifts and reduce capital investment efficiency. Specifically, we find that managers incentivized by high levels of performance-based pay and equity-linked compensation respond to clawback adoptions by shifting capital investments away from R&D and toward capex, thereby lowering capital investment efficiency and contravening purported financial reporting quality and investment efficiency benefits found previously for clawback adoptions. These findings, which are robust to alternative explanations, extend prior evidence by documenting managerial compensation incentives as a channel by which clawback adoptions can influence capital investment mix and capital investment efficiency. These findings are also timely given pending SEC Rule 10D-1 that would make clawback provisions a pre-condition for U.S. exchange listing and which explicitly requests “comment on any effect the proposed requirements may have on efficiency, competition and capital formation” (SEC 2015, 103-104).

Background and objective Periodontitis is a highly prevalent chronic inflammatory disease that causes tooth loss, morbidity and confers an increased risk for systemic disease. Tissue destruction during periodontitis is due in large part to collagen-degrading matrix metalloproteinases (MMPs) released by resident cells of the periodontium in response to proinflammatory cytokines. Platelets are immune-competent blood cells with a newly recognized role in chronic inflammation; however, their role in the pathogenesis of periodontitis is undefined. Consequently, the objective of this study was to assess the effect of platelet factor 4 (PF4), a major platelet-derived cytokine, on MMP-1 (collagenase) expression in human gingival fibroblasts (HGFs). Material and methods HGFs were cultured in the presence or absence of recombinant PF4. Pro-MMP-1 secretion was quantified by enzyme-linked immunosorbent assay analysis of the cell culture supernatants. MMP-1 transcription was quantified by real-time polymerase chain reaction. Regulation of MMP-1 production by the p44/42 MAP kinase (MAPK) signaling pathway was examined in the presence or absence of PF4. Results Exposure to PF4 caused a ~ 2-3-fold increase in MMP-1 transcription and secretion from cultured HGFs. PF4 treatment also enhanced phosphorylation of p44/42 MAPK, which has been previously shown to induce MMP-1 expression in fibroblasts. Blockade of p44/42 MAPK signaling with the cell-permeant inhibitors PD98059 and PD184352 abrogated PF4-induced pro-MMP-1 transcription upregulation and release from cultured HGFs. Conclusion We conclude that PF4 upregulates MMP-1 expression in HGFs in a p44/42 MAPK-dependent manner. These findings point to a previously unidentified role for platelets in the pathogenesis of periodontal diseases.

The instability and accelerated melting of the Antarctic Ice Sheet are among the foremost elements of contemporary global climate change. The increased freshwater output from Antarctica is important in determining sea level rise, the fate of Antarctic sea ice and its effect on the Earth's albedo, ongoing changes in global deep-ocean ventilation, and the evolution of Southern Ocean ecosystems and carbon cycling. A key uncertainty in assessing and predicting the impacts of Antarctic Ice Sheet melting concerns the vertical distribution of the exported meltwater. This is usually represented by climate-scale models as a near-surface freshwater input to the ocean, yet measurements around Antarctica reveal the meltwater to be concentrated at deeper levels. Here we use observations of the turbulent properties of the meltwater outflows from beneath a rapidly melting Antarctic ice shelf to identify the mechanism responsible for the depth of the meltwater. We show that the initial ascent of the meltwater outflow from the ice shelf cavity triggers a centrifugal overturning instability that grows by extracting kinetic energy from the lateral shear of the background oceanic flow. The instability promotes vigorous lateral export, rapid dilution by turbulent mixing, and finally settling of meltwater at depth. We use an idealized ocean circulation model to show that this mechanism is relevant to a broad spectrum of Antarctic ice shelves. Our findings demonstrate that the mechanism producing meltwater at depth is a dynamically robust feature of Antarctic melting that should be incorporated into climate-scale models.

Using newly available data we document that managers voluntarily disclose capex guidance with comparable frequency and continuity to earnings guidance. To explain why, we hypothesize and find that capex guidance is positively related to capital investment efficiency and long-term abnormal stock returns, that managers learn from analyst feedback when making capital investments, that analyst feedback which deviates from capex guidance informs capital investments and improves capital investment efficiency more than confirming feedback, and that CEOs receiving stock-based compensation are more likely to issue capex guidance, consistent with value creation incentives. Considered collectively, our findings are consistent with capex guidance being a prevalent voluntary disclosure commitment that creates firm value via transparency, analyst monitoring and feedback learning that informs and incentivizes capital investment efficiency.

International audience; Prior evidence that higher quality financial reporting improves capital investment efficiency leaves unaddressed whether it reduces over- or under-investment. This study provides evidence of both in documenting a conditional negative (positive) association between financial reporting quality and investment for firms operating in settings more prone to over-investment (under-investment). Firms with higher financial reporting quality also are found to deviate less from predicted investment levels and show less sensitivity to macroeconomic conditions. These results suggest that one mechanism linking reporting quality and investment efficiency is a reduction of frictions such as moral hazard and adverse selection that hamper efficient investment.

Icebergs affect local biological production around Antarctica. We used an ocean glider to observe the effects of a large iceberg that was advected by the Antarctic Slope Current along the continental slope in the northwestern Weddell Sea in early 2012. The high-resolution glider data reveal a pronounced effect of the iceberg on ocean properties, with oxygen concentrations of (13 ± 4) μmol kg^(−1) higher than levels in surrounding waters, which are most likely due to positive net community production. This response was confined to three areas of water in the direct vicinity of the iceberg track, each no larger than 2 km^2. Our findings suggest that icebergs have an impact on Antarctic production presumably through local micronutrient injections, on a scale smaller than typical satellite observations of biological production in the Southern Ocean.

With the International Accounting Standards Board (IASB) now considering the question, we examine 16 different definitions of income across three applications: information content, predictive ability and executive compensation contracting. Our results reveal that comprehensive income defined by FASB Statement 130 (NI130) dominates both traditional net income (NI) and fully comprehensive income (NIbroad) in explaining equity returns, but that NI dominates NI130 and NIbroad in explaining executive compensation. These findings are strikingly consistent with prior lobbying positions. In predictive ability, no definition clearly dominates. When income components are considered, NIbroad dominates in all three applications, thus lending support to the disclosure of comprehensive income components.

Economic reasoning suggests that capital follows profitability. This study introduces into residual income valuation “capital follows profitability” investment dynamics whereby capital investments are guided by the profitability of underlying investment opportunities. These investment dynamics predict convex versus linear relations between future and current residual income, with slope and convexity dependent on investment opportunity. We test these predictions against the linear information dynamics (LID) proposed by Ohlson (1995) and Feltham and Ohlson (1996), with supportive results. These findings point the way to further development of links between firm value and the economics of value creation.

EVA has attracted considerable attention as an alternative to traditional accounting earnings for use in both valuation and incentive compensation. With a host of consultants now marketing related metrics, numerous claims have been made—most based on anecdotal evidence or in-house studies. This paper summarizes the authors' independent evidence regarding EVA's alleged advantages. The authors begin by reviewing the theory that links the underlying concept of residual income to shareholder value. Second, they discuss how Stern Stewart modifies residual income to produce its proprietary EVA metric and show how median EVA compares with residual income, net income, and operating cash flows over the period 1988–97. Third, they examine the claim that EVA is more closely associated with stock returns and firm value than is net income. Their evidence indicates that EVA does not dominate net income in associations with stock returns and firm values. Fourth, they examine a second claim that compensation plans based on residual income motivate managers to take actions consistent with increasing shareholder value. Here the evidence (from a study by Wallace) suggests that managers do respond to residual income-based incentives by, for example, increasing asset sales, cutting capital expenditures, repurchasing stock, and producing higher levels of residual income. The authors conclude by arguing that a metric such as EVA can be effective for internal incentive purposes even if it conveys little news to market participants regarding the firm's valuation.