Director Reputation, Ceo-Board Power, And The Dynamics Of Board Interlocks

This study advances research on CEO-board relationships, interlocking directorates, and director reputation by examining how contests for intraorganizational power can affect interorganizational ties. We propose that powerful top managers seek to maintain their control by selecting and retaining board members with experience on other, passive boards and excluding individuals with experience on more active boards. We also propose that powerful boards similarly seek to maintain their control by favoring directors with a reputation for more actively monitoring management and avoiding directors with experience on passive boards. Hypotheses are tested longitudinally using CEO-board data taken from 491 of the largest U.S. corporations over a recent seven-year period. The findings suggest that variation in CEO-board power relationships across organizations has contributed to a segmentation of the corporate director network. We discuss how our perspective can reconcile contrary views and debates on whether increased board control has diffused across large U.S. corporations.(.)Managemen

Defections From The Inner Circle: Social Exchange, Reciprocity, And The Diffusion Of Board Independence In Us Corporations

This study seeks to reconcile traditional sociological views of the corporate board as an instrument of elite cohesion with recent evidence of greater board activism and control over top management. We propose that CEO-directors may typically support fellow CEOs by impeding increased board control over management but that CEO-directors may also foster this change if they have experienced it in their own corporation. Drawing on social exchange theory, we develop and test the argument that these CEO-directors may experience a reversal in the basis for generalized social exchange with other top managers from one of deference and support to one of independence and control. Using data from a large sample of major U.S. corporations over a recent ten-year period, we show (1) how CEO-directors ''defect'' from the network of mutually supportive corporate leaders, (2) how defections have diffused across organizations and over time, and (3) how this has contributed to increased board control, as measured by changes in board structure, diversification strategy, and contingent compensation. We also provide evidence that a social exchange perspective can explain the diffusion of these changes better than more conventional perspectives on network diffusion that emphasize imitation or learning.Business Administratio

Scalable gate architecture for densely packed semiconductor spin qubits

We demonstrate a 12 quantum dot device fabricated on an undoped Si/SiGe heterostructure as a proof-of-concept for a scalable, linear gate architecture for semiconductor quantum dots. The device consists of 9 quantum dots in a linear array and 3 single quantum dot charge sensors. We show reproducible single quantum dot charging and orbital energies, with standard deviations less than 20% relative to the mean across the 9 dot array. The single quantum dot charge sensors have a charge sensitivity of 8.2 x 10^{-4} e/root(Hz) and allow the investigation of real-time charge dynamics. As a demonstration of the versatility of this device, we use single-shot readout to measure a spin relaxation time T1 = 170 ms at a magnetic field B = 1 T. By reconfiguring the device, we form two capacitively coupled double quantum dots and extract a mutual charging energy of 200 microeV, which indicates that 50 GHz two-qubit gate operation speeds are feasible

Increased plasma concentration of vascular endothelial growth factor in patients with atopic dermatitis and its relation to disease severity and platelet activation

BACKGROUND: Overproduction of vascular endothelial growth factor (VEGF) in atopic dermatitis (AD) lesions has previously been observed. It is also known that platelet is an important source of VEGF and platelet factor 4 (PF-4), a potential marker of AD severity. AIM: To evaluate concentrations of VEGF and its soluble receptors (sVEGF-R1 and sVEGF-R2) in the plasma of AD patients and to examine its possible correlation with disease severity and plasma concentrations of PF-4, a platelet activation marker. METHODS: Plasma concentrations of VEGF and its receptors and levels of PF-4 were measured by an immunoenzymatic assay in 51 AD patients and in 35 healthy non-atopic controls. The severity of the disease was evaluated using the eczema area and severity index. RESULTS: AD patients showed significantly increased VEGF and PF-4 plasma concentrations as compared with the controls. Plasma concentrations of sVEGF-R1 and sVEGF-R2 did not differ between the groups. There were no remarkable correlations between plasma VEGF concentration and disease severity or between VEGF and PF-4 concentration. CONCLUSIONS: This study shows that plasma concentration of VEGF may be increased in patients suffering from AD. It seems that plasma VEGF concentration is not a useful marker of disease severity and, apart from platelets, other cells might also release the cytokine

Screening nuclear field fluctuations in quantum dots for indistinguishable photon generation

A semiconductor quantum dot can generate highly coherent and indistinguishable single photons. However, intrinsic semiconductor dephasing mechanisms can reduce the visibility of two-photon interference. For an electron in a quantum dot, a fundamental dephasing process is the hyperfine interaction with the nuclear spin bath. Here we directly probe the consequence of the fluctuating nuclear spins on the elastic and inelastic scattered photon spectra from a resident electron in a single dot. We find the nuclear spin fluctuations lead to detuned Raman scattered photons which are distinguishable from both the elastic and incoherent components of the resonance fluorescence. This significantly reduces two-photon interference visibility. However, we demonstrate successful screening of the nuclear spin noise which enables the generation of coherent single photons that exhibit high visibility two-photon interference.Comment: 5 pages, 4 figures + Supplementary Informatio

The Symbolic Management Of Stockholders: Corporate Governance Reforms And Shareholder Reactions

This paper examines the consequences of symbolic action in corporate governance. Specifically, we examine (1) whether the stock market reacts favorably to specific governance mechanisms that convey the alignment of CEO and shareholder interests, such as the adoption of long-term incentive plans (LTIPs), even if such plans are not actually implemented, (2) whether providing agency-related explanations for LTIPs affects the stock market response, and (3) whether the symbolic adoption of LTIPs deters other governance reforms that would reduce CEOs' control over their boards. Analysis of data from over 400 corporations over a ten-year period suggests that symbolic corporate actions can engender significant positive stockholder reactions and deter other, more substantive governance reforms, thus perpetuating power imbalances in organizations. We discuss implications for institutional and agency-based perspectives on organizations.Business Administratio

Decoupling Policy From Practice: The Case Of Stock Repurchase Programs

This study examines firms' decoupling of informal practices from formally adopted policies through analysis of the implementation of stock repurchase programs by large U.S. corporations in the late 1980s and early 1990s, when firms were experiencing external pressures to adopt policies that demonstrate corporate control over managerial behavior. We develop theory to explain variation in the responses of firms to such pressures, i.e., why some firms acquiesce by actually implementing stock repurchase programs, while others decouple formally adopted repurchase programs from actual corporate investments, so that the plans remain more symbolic than substantive. Results of a longitudinal study of stock repurchase programs over a six-year time period show that decoupling is more likely to occur when top executives have power over boards to avoid institutional pressures for change and when social structural or experiential factors enhance awareness among powerful actors of the potential for organizational decoupling. The study has implications for future research on decoupling, organizational learning, and corporate governance.Managemen

Effect of Mn and Mg dopants on vacancy defect formation in ammonothermal GaN

We have applied positron annihilation spectroscopy to study the formation of Ga vacancy related defects in Mg and Mn doped bulk GaN crystals grown by the ammonothermal method. We show that Mn doping has little or no effect on the formation of Ga vacancies, while Mg doping strongly suppresses their formation, in spite of both dopants leading to highly resistive material. We suggest the differences are primarily due to the hydrogen-dopant interactions. Further investigations are called for to draw a detailed picture of the atomic scale phe-nomena in the synthesis of ammonothermal GaN.Peer reviewe