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In this study, we concentrate on the seismic signature of subducted sediments and suggest the formation of the L‐discontinuity beneath the ancient craton related to migrated sediment dehydration. We first determined the single‐crystal elasticity of topaz, the product of sediment dehydration, at high pressures and temperatures by Brillouin scattering. Using the derived elastic parameters, we establish the velocity and density profiles of subducted sediments in the upper mantle. According to our modeling results, 8.5–17.5 vol.% sediments intruding into the upper mantle will induce a 2%–4% low‐VS anomaly at 210–260 km. Meanwhile, continuous heating will lead to the dehydration of phengite in sediments. The dehydration of this amount sediments can generate a 3%–6% ISS with negative Clapeyron slopes, satisfying the observed L‐discontinuity in northern Finland and northern America without the anisotropy changes but accompanied by low‐velocity anomalies. Our study thus provides new insights into the origin of the L‐discontinuity. Plain Language Summary The origin of the global seismic discontinuities in the Earth's mantle has been well understood, but the formation mechanism of some local seismic discontinuities is still vague. Lehmann discontinuity (L‐discontinuity) is one of the regional discontinuities in the upper mantle with a 2%–6% impendence contrast (ISS) and negative Clapeyron slope. However, the deformation mechanism changes of olivine cannot explain the formation of the L‐discontinuity without the anisotropy changes. Here, we emphasize the significance of the migration and dehydration of the subducted sediments in the origin of the L‐discontinuity beneath the ancient craton. We determined the single‐crystal elasticity of topaz, the product of the sediment dehydration, and then investigated the seismic signature of subducted sediments. Our modeling results indicated that ∼17.5 vol.% sediments intruding into the upper mantle would lead to ∼4% low‐VS anomalies at 210–260 km. After the continuous heating, these intruding sediments would dehydrate by the reaction with the negative Clapeyron slopes, thus producing significant ISS. Therefore, the migration and dehydration of the subducted sediments can reasonably interpret the seismic characteristics of the L‐discontinuity beneath the cratonic regions such as northern Finland and northern America. Our results deepen the understanding of the origin of the L‐discontinuity. Key Points Single‐crystal elasticity of topaz under high pressure and temperature has been investigated by Brillouin scattering The obtained elasticity parameters are used to model the density and velocity profiles of the subducted sediments We suggest the formation of the L‐discontinuity beneath the ancient craton related to migrated sediment dehydration

We investigate how firms react to their product-market peers’ commitment to and adoption of corporate social responsibility (CSR) using a regression discontinuity design approach. Relying on the passage or failure of CSR proposals by a narrow margin of votes during shareholder meetings, we find the passage of a close-call CSR proposal and its implementation are followed by the adoption of similar CSR practices by peer firms. In addition, peers that have greater difficulty in catching up with the voting firm in CSR experience significantly lower stock returns around the passage, consistent with the notion that the spillover effect of the adoption of CSR is a strategic response to competitive threat. Using alternative definitions of peers and examining underlying mechanisms, we further rule out alternative explanations, such as that based on propagation by financial intermediaries. This paper was accepted by Gustavo Manso, finance department.

This study wants to give a contribution to the semi-automatic evaluation of rock mass discontinuities, orientation and spacing, as important parameters used in Engineering. In complex and inaccessible study areas, a traditional geological survey is hard to conduct, therefore, remote sensing techniques have proven to be a very useful tool for discontinuity analysis. However, critical expert judgment is necessary to make reliable analyses. For this reason, the open-source Python tool named DCS (Discontinuities Classification and Spacing) was developed to manage point cloud data. The tool is written in Python and is based on semi-supervised clustering. By this approach the users can: (a) estimate the number of discontinuity sets (here referred to as “clusters”) using the Error Sum of Squares (SSE) method and the K-means algorithm; (b) evaluate step by step the quality of the classification visualizing the stereonet and the scatterplot of dip vs. dip direction from the clustering; (c) supervise the clustering procedure through a manual initialization of centroids; (d) calculate the normal spacing. In contrast to other algorithms available in the literature, the DCS method does not require complex parameters as inputs for the classification and permits the users to supervise the procedure at each step. The DCS approach was tested on the steep coastal cliff of Ancona town (Italy), called the Cardeto–Passetto cliff, which is characterized by a complex fracturing and is largely affected by rockfall phenomena. The results of discontinuity orientation were validated with the field survey and compared with the ones of the FACETS plug-in of CloudCompare. In addition, the algorithm was tested and validated on regular surfaces of an anthropic wall located at the bottom of the cliff. Eventually, a kinematic analysis of rock slope stability was performed, discussing the advantages and limitations of the methods considered and making fundamental considerations on their use.

Research summary: In this paper, we theorize and empirically investigate how a long-term orientation impacts firm value. To study this relationship, we exploit exogenous changes in executives' long-term incentives. Specifically, we examine shareholder proposals on long-term executive compensation that pass or fail by a small margin of votes. The passage of such \"close call\" proposals is akin to a random assignment of long-term incentives and hence provides a clean causal estimate. We find that the adoption of such proposals leads to (1) an increase in firm value and operating performance—suggesting that a long-term orientation is beneficial to companies—and (2) an increase in firms' investments in long-term strategies such as innovation and stakeholder relationships. Overall, our results are consistent with a \"time-based\" agency conflict between shareholders and managers. Managerial summary: This paper shows that corporate short-termism is hampering business success. We show clear, causal evidence that imposing long-term incentives on executives—in the form of long-term executive compensation—improves business performance. Long-term executive compensation includes restricted stocks, restricted stock options, and long-term incentive plans. Firms that adopted shareholder resolutions on long-term compensation experienced a significant increase in their stock price. This stock price increase foreshadowed an increase in operating profits that materialized after two years. We unpack the reasons for these improvements in performance, and find that firms that adopted these shareholder resolutions made more investments in R&D and stakeholder engagement, especially pertaining to employees and the natural environment.

The mechanisms governing a commonly observed seismic velocity drop in the cratonic lithosphere, referred to as the mid‐lithospheric discontinuity (MLD), have been widely debated. To identify the composition and seismic structure of MLDs, we have analyzed Sp receiver functions (SRF) and mantle xenocrysts for six regions across Australia. We utilize locations where seismic stations and kimberlite‐hosted mantle xenocrysts are both available, allowing for comparison between seismological and petrological constraints. Our results show negative SRF phases indicative of the MLD coincide with clinopyroxene‐depleted zones at 60–140 km depth. Clinopyroxenes with different chemical compositions across the MLD define a litho‐chemical discontinuity. Modeling and experimental data show that MLDs may be explained by modified lherzolite with 10%–20% modal pargasite. Pargasite MLDs may form when rising H2O‐bearing melts cross the amphibole dehydration curve and react with clinopyroxene in lherzolite. Because the amphibole dehydration curve is isobaric at 80–120 km, pargasite will be precipitated as horizontal channels. Plain Language Summary Seismic imaging of Earth's lithosphere has revealed a seismic velocity drop at 60–120 km depth, termed the mid‐lithosphere discontinuity (MLD). The mechanisms governing the MLD have been extensively debated. To advance the understanding of the MLD we carried out an interdisciplinary study to investigate the seismic structure and composition of MLDs identified in the cratonic lithosphere of Australia. We integrated analysis of seismic converted signals from discontinuities recorded by permanent seismometers with geochemical data for kimberlite‐hosted mantle xenocrysts collected in the vicinity. The method allows direct comparison between seismological and petrological constraints. Our results suggest that the MLD comprises anomalously low abundances of clinopyroxene and separates geochemically distinct layers within the lithospheric mantle. Experimental results and modeling suggests that the observed decrease in seismic velocity and absence of clinopyroxene may relate to the formation of pargasite channels in modified lherzolite. Key Points Sp receiver functions and mantle xenocrysts are used to study mid‐lithosphere discontinuities beneath Australian cratons Mid‐lithosphere discontinuity at 60–120 km depth corresponds with mantle xenocryst populations that are depleted in clinopyroxene Modeling and experimental data suggests the mid‐lithosphere discontinuity is caused by pargasite‐bearing lherzolite

This study examines the effect of shareholder proposals related to corporate social responsibility (CSR) on financial performance. Specifically, I focus on CSR proposals that pass or fail by a small margin of votes. The passage of such “close call” proposals is akin to a random assignment of CSR to companies and hence provides a quasi-experiment to study the effect of CSR on performance. I find that the adoption of close call CSR proposals leads to positive announcement returns and superior accounting performance, implying that these proposals are value enhancing. When I examine the channels through which companies benefit from CSR, I find that labor productivity and sales growth increase after the vote. Finally, I document that close call CSR proposals differ from non-close proposals along several dimensions. Accordingly, although my results imply that adopting close call CSR proposals is beneficial to companies, they do not necessarily imply that CSR proposals are beneficial in general. Data, as supplemental material, are available at http://dx.doi.org/10.1287/mnsc.2014.2038 . This paper was accepted by Wei Jiang, finance .

In the regression-discontinuity (RD) design, units are assigned to treatment based on whether their value of an observed covariate exceeds a known cutoff. In this design, local polynomial estimators are now routinely employed to construct confidence intervals for treatment effects. The performance of these confidence intervals in applications, however, may be seriously hampered by their sensitivity to the specific bandwidth employed. Available bandwidth selectors typically yield a \"large\" bandwidth, leading to data-driven confidence intervals that may be biased, with empirical coverage well below their nominal target. We propose new theory-based, more robust confidence interval estimators for average treatment effects at the cutoff in sharp RD, sharp kink RD, fuzzy RD, and fuzzy kink RD designs. Our proposed confidence intervals are constructed using a bias-corrected RD estimator together with a novel standard error estimator. For practical implementation, we discuss mean squared error optimal bandwidths, which are by construction not valid for conventional confidence intervals but are valid with our robust approach, and consistent standard error estimators based on our new variance formulas. In a special case of practical interest, our procedure amounts to running a quadratic instead of a linear local regression. More generally, our results give a formal justification to simple inference procedures based on increasing the order of the local polynomial estimator employed. We find in a simulation study that our confidence intervals exhibit close-to-correct empirical coverage and good empirical interval length on average, remarkably improving upon the alternatives available in the literature. All results are readily available in R and STATA using our companion software packages described in Calonico, Cattaneo, and Titiunik (2014d, 2014b).

Recent research has paid little attention to the shear damage of discontinuities with different joint wall material (DDJM). In this paper, we present an investigation on the evolution of the shear behaviour and the damage of three typical types of natural DDJM in a sliding-prone stratum of China. Experimental direct shear tests were performed on 14 pairs of natural DDJM specimens to examine the changes in the shear strengths and surface damages of the DDJM with increasing normal stresses and an increasing number of shear cycles by evaluating surface damages via damage zone distribution, damage area percentage, and variation of joint roughness coefficient (JRC). The results indicate that the differences in the shear damage between the two halves are closely related to the difference in strength of the two joint walls of the DDJM specimens with similar initial JRC values of the two joint surfaces. Simultaneously, parallel numerical direct shear tests were conducted in PFC3D. The performance of the numerical modeling was examined by comparing the parameters of shear strength, damage area and damage depth of DDJM specimens with those obtained in the experimental direct shear tests. Then the validated models were used to explore the evolution of the damage depth of DDJM specimens during the shearing process. The results demonstrate that the proposed numerical approach has the ability to reproduce the shear behavior and damage of DDJM reasonably and could be used to examine the internal damage of DDJM which are not easy to investigate via laboratory experiments.

Compressional and shear wave velocities of polycrystalline stishovite (SiO2) have been measured at simultaneous high pressures and temperatures up to 14.5 GPa and 800°C. By fitting velocities to the finite strain equations, the elastic moduli and density were determined to be KS0 = 306.6(46) GPa, KS′ = 4.92(10), ∂KS/∂T = −0.024(1) GPa/K, G0 = 229.0(34) GPa, G′ = 1.07(10), ∂G/∂T = −0.017(1) GPa/K, ρ0 = 4.287(2) g/cm3. Our modeling suggested that, in the eclogite, coesite‐stishovite transition can increase P and S wave velocities by 2.4% and 3.5%, respectively. A comparison between geophysical observations and our model shows that the coesite‐stishovite phase transition in the eclogite can potentially be responsible for the occurrence of the X discontinuity beneath Hawaii. In addition, our current results suggest an eclogite‐rich layer between 340 and 450 km depth beneath Hawaii. The eclogite concentration at the top and bottom of the layer is 41–55 vol% and >77 vol%, respectively. Plain Language Summary In this study, we investigated the elastic behavior of stishovite, a high‐pressure mineral found in subducted oceanic crust, under simultaneous high pressure and high temperature. By measuring compressional and shear wave velocities of polycrystalline stishovite at pressures up to 14.5 GPa and temperatures up to 800°C, we determined elastic modulus for stishovite. Using current data, we developed a model to predict seismic wave velocities changes in the subducted oceanic crust known as eclogite. According to our model, the coesite‐stishovite phase transition can lead to a 2.4% and 3.5% increase in P and S wave velocities of eclogite, respectively. In addition, we compared it with geophysical observations, particularly focusing on the X discontinuity beneath Hawaii. Our result indicates the presence of an eclogite‐rich layer beneath Hawaii, extending from 340 to 450 km in depth. The concentration of eclogite at the top and bottom of this layer varies, with values ranging from 41% to 55% at approximately 336 km and exceeding 77% at around 448 km depth. Key Points Direct measurement of P and S wave velocities of stishovite at mantle pressures and temperatures In the eclogite, coesite‐stishovite transition can result in seismically detectable first order increase in P and S velocities An eclogite‐rich layer model can interpret the seismic X‐discontinuity in Hawaii area

This article reconsiders the double-slit experiment from the nonrealist or, in terms of this article, “reality-without-realism” (RWR) perspective, grounded in the combination of three forms of quantum discontinuity: (1) “Heisenberg discontinuity”, defined by the impossibility of a representation or even conception of how quantum phenomena come about, even though quantum theory (such as quantum mechanics or quantum field theory) predicts the data in question strictly in accord with what is observed in quantum experiments); (2) “Bohr discontinuity”, defined, under the assumption of Heisenberg discontinuity, by the view that quantum phenomena and the data observed therein are described by classical and not quantum theory, even though classical physics cannot predict them; and (3) “Dirac discontinuity” (not considered by Dirac himself, but suggested by his equation), according to which the concept of a quantum object, such as a photon or electron, is an idealization only applicable at the time of observation and not to something that exists independently in nature. Dirac discontinuity is of particular importance for the article’s foundational argument and its analysis of the double-slit experiment.