Browsing by Author "Zhang, Yan"

Now showing 1 - 9 of 9
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    A Displaced Lower Mantle Source of the Hainan Plume in South China Revealed by Receiver Function Imaging of the CEArray
    (Wiley, 2024) Zhang, Yan; Niu, Fenglin; Ning, Jieyuan; Yu, Chunquan
    We analyzed 49,592 teleseismic receiver functions (RFs) recorded by 278 CEArray stations to image the mantle transition zone (MTZ) beneath the South China Block to understand the origins of deep velocity anomalies and their potential links to subduction and intraplate volcanism. We employed a fast-marching method and a high-resolution 3-D velocity model (FWEA18) derived from full waveform inversion in computing P-to-S conversion times to better image the 410- and 660-km discontinuities. Our results indicate that the common-conversion-point stacking of RFs using 3-D conversion times yielded better migration images of the two discontinuities. The images revealed a slightly depressed 410-km with a few small uplifted patches, and showed that the 660-km beneath the western Yangtze Craton is depressed by 10–25 km, which is likely caused by the stagnant Paleo-Pacific slab. The 660-km beneath the southern Cathaysia Block has a 5–15 km high plateau with a topographic low at its central part. The lateral dimension of the topographic low is ∼150 km and is located beneath the central Pearl River Mount Basin near Hong Kong. We speculate that the topographic low occurs within the Hainan plume with a temperature excess of ∼300–400 K and is caused by the garnet phase transition. The displaced deep plume enters the MTZ and spreads nearly horizontally at the base. The plume evolves into two channels with a minor one toward the northeast and a major one toward the southwest, which keep moving upward to the 410-km. The southwest channel is likely the source that feeds the Hainan volcanoes.
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    Dilemmas and Triads: The Strategic Use of Corporate Venture Capital Investments
    (2023-04-21) Kwon, Yoon Jung; Zhang, Yan
    This dissertation explores how industry incumbents use corporate venture capital (CVC) to achieve strategic objectives and identifies multiple dilemmas and challenges associated with the investments. In each of the three essays in the dissertation, I extend the perspective beyond the traditional dyadic view on CVC investments and examine how different parties and institutional environments could affect CVC investments. The first essay explores the dilemma that CVC investors face when investing in entrepreneurial ventures that develop substitutive technologies. The findings suggest that on average, incumbents are less likely to invest in substitutive versus complementary ventures. However, under industry-wide pressures, syndication with industry competitors could help them mitigate the concerns associated with such investments. The second essay explores the dilemma that CVC investors face when investing in spinouts of other industry incumbents due to the conflict of learning benefits versus competitive risks involved with the investments. The findings suggest that the competitive risks discourage CVCs’ investments in other incumbents’ spinouts, but this affect is attenuated when there are substantial learning benefits associated with the investments. The third essay explores the dilemma that CVC investors face when external institutional demands conflict with internal efficiency. The findings suggest that when faced with legitimacy challenges, incumbents could use CVC investments as an impression management mechanism to address external demands. In addition, firms that have a greater gap between what they are 'expected to do' versus what they are ‘actually doing’ are more likely to make such investments, particularly if the ventures' industry segments are more compatible with their own. Through the three essays, I aim to contribute to the literature on CVC investments by expanding the perspective beyond the CVC investor-investee dyad and examining underexplored assumptions and dilemmas in the CVC literature, ultimately extending our understanding on how CVC investments could be strategically utilized by industry incumbents.
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    Essays on CEO cognitive complexity: Effects on corporate strategy, performance, and survival
    (2017-04-18) Zyung, Daniel; Zhang, Yan
    The Chief Executive Officer’s (CEO’s) job involves a substantial amount of information processing. This dissertation explores the organizational implications of CEOs’ way of processing information, or cognitive style, in multiple contexts. I particularly focus on CEOs’ cognitive complexity, or their degree of differentiation and integration of information, and examine how it influences their corporate strategies and performance outcomes not only in general business settings but also in high-growth environments as well as crisis situations. First, I examine the influence of CEOs’ cognitive complexity on their firms’ growth strategies and how these relationships change as the industry in which they compete grows itself. Second, I focus on a particular research context, the recent financial crisis of 2007-2008, to examine how firm acquisitions prior to the crisis, in part driven by their CEOs’ cognitive complexity, influence acquisitions during the crisis which in turn may affect firms’ subsequent survival. Finally, while maintaining the focus on the recent financial crisis, I broaden the focus on firm strategies to their corporate restructuring activities—i.e., acquisitions and divestitures—to examine how these two strategies unfolded within each course and across each other, by comparing pre- and during-crisis periods. Further, I examine the role of CEOs’ cognitive complexity in these ‘cross-strategy’ effects and the specific impacts of during-crisis restructuring activities on firms’ subsequent performance and survival.
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    Human Omental-Derived Adipose Stem Cells Increase Ovarian Cancer Proliferation, Migration, and Chemoresistance
    (Public Library of Science, 2013) Nowicka, Aleksandra; Marini, Frank C.; Solley, Travis N.; Elizondo, Paula B.; Zhang, Yan; Sharp, Hadley J.; Broaddus, Russell; Kolonin, Mikhail; Mok, Samuel C.; Thompson, Melissa S.; Woodward, Wendy A.; Lu, Karen; Salimian, Bahar; Nagrath, Deepak; Klopp, Ann H.
    Objectives: Adipose tissue contains a population of multipotent adipose stem cells (ASCs) that form tumor stroma and can promote tumor progression. Given the high rate of ovarian cancer metastasis to the omental adipose, we hypothesized that omental-derived ASC may contribute to ovarian cancer growth and dissemination. Materials and Methods: We isolated ASCs from the omentum of three patients with ovarian cancer, with (O-ASC4, O-ASC5) and without (O-ASC1) omental metastasis. BM-MSCs, SQ-ASCs, O-ASCs were characterized with gene expression arrays and metabolic analysis. Stromal cells effects on ovarian cancer cells proliferation, chemoresistance and radiation resistance was evaluated using co-culture assays with luciferase-labeled human ovarian cancer cell lines. Transwell migration assays were performed with conditioned media from O-ASCs and control cell lines. SKOV3 cells were intraperitionally injected with or without O-ASC1 to track in-vivo engraftment. Results: O-ASCs significantly promoted in vitro proliferation, migration chemotherapy and radiation response of ovarian cancer cell lines. O-ASC4 had more marked effects on migration and chemotherapy response on OVCA 429 and OVCA 433 cells than O-ASC1. Analysis of microarray data revealed that O-ASC4 and O-ASC5 have similar gene expression profiles, in contrast to O-ASC1, which was more similar to BM-MSCs and subcutaneous ASCs in hierarchical clustering. Human O-ASCs were detected in the stroma of human ovarian cancer murine xenografts but not uninvolved ovaries. Conclusions: ASCs derived from the human omentum can promote ovarian cancer proliferation, migration, chemoresistance and radiation resistance in-vitro. Furthermore, clinical O-ASCs isolates demonstrate heterogenous effects on ovarian cancer in-vitro.
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    Hydraulic Injection‐Induced Velocity Changes Revealed by Surface Wave Coda and Polarization Data at a Shale Play Site in Southwest China
    (Wiley, 2020) Zhang, Yan; Niu, Fenglin; Tao, Kai; Ning, Jieyuan; Chen, Haichao; Tang, Youcai
    We investigated temporal variations of seismic wave velocity associated with hydraulic fracturing using Green's functions computed from ambient noise data. In October and November of 2014, we set up a broadband array at a shale play site inside the Sichuan basin where a pilot horizontal drilling and hydraulic injections were conducted. We first computed cross‐correlation functions using continuous data recorded by 21 three‐component broadband sensors deployed around the treatment well. We then employed a running window correlation‐based coda wave interferometry technique to measure apparent velocity changes from the daily Green's functions of all the station pairs in the frequency range of 1 to 3 Hz. We found significant velocity changes right after the hydraulic fracturing, which exhibited a clear direction‐dependent pattern. S wave velocity along raypaths parallel to the well trajectory showed a clear increase while those perpendicular exhibited a small decrease. The anisotropic changes in seismic velocity observed here were also confirmed from surface wave horizontal particle motion data. By comparing our observations with normal stress changes calculated with a half‐space elastic model, we speculate that stress changes induced by the hydraulic fracturing were likely to be responsible for the observed anisotropic changes in seismic velocity. Our results suggest that time‐lapse seismic imaging with ambient noise data provides a promising probe for monitoring geomechanical changes related to exploitation of unconventional oil and gas resources.
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    Nematic magnetoelastic effect contrasted between Ba(Fe1−xCox)2As2 and FeSe
    (American Physical Society, 2016) Hu, Yuwen; Ren, Xiao; Zhang, Rui; Luo, Huiqian; Kasahara, Shigeru; Watashige, Tatsuya; Shibauchi, Takasada; Dai, Pengcheng; Zhang, Yan; Matsuda, Yuji; Li, Yuan
    To elucidate the origin of nematic order in Fe-based superconductors, we report a Raman scattering study of lattice dynamics, which quantify the extent of C4-symmetry breaking, in BaFe2As2 and FeSe. FeSe possesses a nematic ordering temperature Ts and orbital-related band-energy split below Ts that are similar to those in BaFe2As2, but unlike BaFe2As2 it has no long-range magnetic order. We find that the Eg phonon-energy split in FeSe becomes substantial only well below Ts, and its saturated value is much smaller than that in BaFe2As2. Together with reported results for the Ba(Fe1−xCox)2As2 family, the data suggest that magnetism exerts a major influence on the lattice.
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    Three Essays on CEO Severance Pay
    (2019-08-09) Callahan, Conor John; Zhang, Yan
    The majority of CEOs at U.S. public companies are promised severance pay in their compensation packages, yet researchers have thus far rarely considered the importance of these arrangements. This dissertation consists of three essays on CEO severance pay. My first essay draws upon agency theory to empirically demonstrate that a greater proportion of severance pay can offset employment risk for newly appointed executives, leading to firm strategies with greater distinctiveness. I also find that this relationship is amplified when CEOs receive a greater proportion of stock option payment in their initial package but attenuated when CEOs have appointed a greater proportion of directors on the board. Findings from my second essay present empirical evidence as to which incoming CEOs have a greater proportion of severance pay in their initial employment agreement. Specifically, I find general support for my theoretical argument that factors associated with the employment risk of incoming CEOs are also antecedents to the proportion of severance pay awarded to CEOs. The third essay of my dissertation is conceptual, and considers the ex-post impact of severance payments to dismissed CEOs. In this essay I develop our understanding of the outcomes impacting firms which award such payments. This dissertation can contribute to strategy research by highlighting the importance of CEO severance pay as a form of executive compensation.
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    Three Essays on CEO Succession
    (2016-04-20) Yi, Xiwei; Zhang, Yan; Windosr, Duane
    This dissertation focuses on how newly appointed CEOs manage their leadership transition process and consists of three empirical essays. Findings from the first essay indicate that newly appointed CEOs could use influence tactics to manage relationship with important organizational constituents. Specifically, ingratiation enhances the new CEO’s social approval based on interpersonal liking and improves the new CEO’s relationship with the predecessor CEO who was retained as the current board chair while self-promotion enhances the new CEO’s social approval based on recognition of competence and reduces shareholders’ misbelief about the new CEO. Findings from the second essay suggest that outside CEOs could communicate their early action plans with important organizational stakeholders to improve their early-stage evaluation. Specifically, I find poor presuccession performance and the dismissal of predecessor CEO will increase the outside CEO’s number of early action plans and the number of the outside CEO’s early action plans will be positively associated with postsuccession analyst recommendation change. In addition, the outside CEO’s prior advantageous work experience (prior intra-industry experience, prior CEO experience and prior experience in “CEO factories”) will strengthen the positive relationship between the number of the outside CEO’s early action plans and postsuccession analyst recommendation change. Findings from the third essay suggest firms experience negative stock market reaction when they dismiss newly appointed CEOs while their rival firms experience positive stock market reaction to the same dismissal. In addition, rival firms that are in closer amount of sales revenue, and/or have more geographic market overlap and/or have more analyst coverage overlap will experience a more positive stock market reaction.
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    Three Essays on Firms' Management and Exploitation of Corporate Venture Capital Investments
    (2020-04-22) Chen, Zhuo; Zhang, Yan
    Researchers in strategic management are increasingly interested in the role of corporate venture capital (CVC) investments in learning about external technologies and improving internal innovation. In this three-essay dissertation, I examine how firms manage and exploit CVC investments to facilitate the learning process. In Essay 1, I examine information externality of CVC investments. I propose that firms may attend to other firms’ CVC investments and take strategic actions by inferring investing firms’ strategic intent from their investments. In the context of acquisitions as the strategic action, I find that acquirers are more likely to acquire ventures in technology domains with a higher intensity of other firms’ CVC investments and this relationship is stronger if the domain has high technological proximity to the acquirer. I also find that technological proximity between an acquirer and a CVC increases the likelihood that the acquirer will acquire ventures that have received investments from the CVC. In Essay 2, I examine firms’ use of CVC investments to facilitate identification of acquisition targets in distant technological domains. I suggest that while firms are less likely to acquire ventures in more distant technological domains, such negative relationship is weaker if the potential target has high technological proximity to the firm’s CVC portfolio. I further advocate that firms are more proficient in using information and knowledge gained through CVC investing to facilitate acquisition of distant targets when they have more prior acquisition experience. In Essay 3, I examine CVC portfolio configuration. I propose that firms configure their CVC portfolios along two dimensions – technological distance between the firm and its CVC portfolio and heterogeneity of the CVC portfolio. I find that firms will choose a subsequent investee such that the heterogeneity of the updated CVC portfolio (after adding the new investee) is negatively related to the technological distance between the firm and its current CVC portfolio. I also find that firms’ learning from its CVC portfolio is positively related to heterogeneity of the CVC portfolio, but such relationship is weakened if the technological distance between the investing firm and its CVC portfolio is high.