GPU加速随机线性网络编码的研究

网络编码近年来被广泛用于各种分布式系统以提高吞吐量,并且能在网络发生动态变化时的数据传输提供弹性。但是,网络编码引起的大量的额外计算量和编码时间成为了实际应用的障碍。在这个研究中,我们使用GPU的强大计算能力来加速网络编码。通过将大量可并行的计算安排到GPU上执行,有效地缩短了网络编码所需要的时间,为网络编码的实际应用提供了帮助。     

When Necessity Becomes a Virtue: The Effect of Product Market Competition on Corporate Social Responsibility

We test whether Corporate Social Responsibility (CSR) is driven by strategic considerations by empirically studying the link between competition and firms' social performance. We find that firms in more competitive industries have better social ratings. In particular, we show that (i) different market concentration proxies are negatively related to widely used CSR measures; (ii) that an increase in competition due to higher import penetration leads to superior CSR performance; (iii) that firms in more competitive environments have a superior environmental performance, measured by firm pollution levels; and (iv) that more product competition is associated to a larger within‐industry CSR variance. We interpret these results as evidence that CSR is strategically chosen.     

Treatment effect bounds: An application to Swan–Ganz catheterization

We reanalyze data from the observational study by Connors et al. (1996) on the impact of Swan–Ganz catheterization on mortality outcomes. The study by Connors et al. (1996) assumes that there are no unobserved differences between patients who are catheterized and patients who are not catheterized and finds that catheterization increases patient mortality. We instead allow for such differences between patients by implementing both the instrumental variable bounds of Manski (1990), which only exploits an instrumental variable, and the bounds of Shaikh and Vytlacil (2011), which exploit mild nonparametric, structural assumptions in addition to an instrumental variable. We propose and justify the use of indicators of weekday admission as an instrument for catheterization in this context. We find that in our application, the Manski (1990) bounds do not indicate whether catheterization increases or decreases mortality, where as the Shaikh and Vytlacil (2011) bounds reveal that at least for some diagnoses, Swan–Ganz catheterization reduces mortality at 7 days after catheterization. We show that the bounds of Shaikh and Vytlacil (2011) remain valid under even weaker assumptions than those described in Shaikh and Vytlacil (2011). We also extend the analysis to exploit a further nonparametric, structural assumption–that doctors catheterize individuals with systematically worse latent health–and find that this assumption further narrows these bounds and strengthens our conclusions. In our analysis, we construct confidence regions using the methodology developed in Romano and Shaikh (2008). We show in particular that the confidence regions are uniformly consistent in level over a large class of possible distributions for the observed data that include distributions where the instrument is arbitrarily “weak”.     

Food-For-Work versus Cash-For-Work: Emergency Assistance in Palestine

In this paper we analyse the provision of emergency assistance (food assistance, cash transfers, employment programmes, etc) to a country whose economy has been decimated since the start of the second intifada. We try to simulate the different potential effects brought about by these different policies and, in particular, to draw some policy implications concerning the Food-for-Work versus Cash-for-Work debate. To that end we have constructed a general equilibrium model of the Palestinian economy that we calibrate on the (pre-intifada) Social Accounting Matrix (SAM) of 1998. We give a so-called 'intifada-shock' to construct a counterfactual 'post-intifada' SAM which serves as basis for our policy simulations. We show that monetary aid from abroad is to be preferred to food aid from abroad. We argue that a labour-oriented approach (subsidizing the most labour-intensive sectors) is to be preferred to a welfare-oriented approach where the subsidized sectors produce those goods that dominate the consumption basket.     

Identity, reputation and social interaction with an application to sequential voting

We analyze binary choices in a random utility model assuming that agent’s preferences are affected by conformism (with respect to the behavior of the society) and coherence (with respect to identity). We show that multiple stationary equilibria may arise and that the outcome looks very different from a society where all the agents take their decisions in isolation. We quantify the fraction of agents that behave coherently. We apply the analysis to sequential voting when voters “like to win”. Compared to the present literature, we enrich the setting assuming that each voter is endowed with an ideology and we consider the interplay between coherence and the desire to vote with the (perceived) majority.     

The virtue of human universals and cooperation: a review essay of Matt Ridley's The Origins of Virtue

In reviewing Matt Ridley's The Origins of Virtue we do five things. (1) We discuss and challenge the basic assumptions of the Standard Social Sciences Model which permeates management scholarship. (2) We present some alternatives to this model, particularly evolutionary psychology. (3) We look at how these alternatives provide a framework for understanding cooperation. (4) We enumerate some of the difficulties (both real and imaginary) with evolutionary psychology. (5) Finally, we suggest that management scholars work more closely with scholars from the many other disciplines that are developing solid theories of cooperation. © 1997 John Wiley & Sons, Ltd.     

Fearlessly Swimming Upstream to Risky Waters: The Role of Geographic Entry in Innovation

We examine the puzzling geographic pattern that shows firms entering countries with weak intellectual property rights (IPR) protection with their research and development (R&D) activities. Geographic entry into weak IPR protection countries is at odds with conventional wisdom as such an environment erodes a firm's ability to appropriate from its innovations. We offer that while the well‐established practice of spreading out a firm's value chain activities across a region has important implications for value creation, what remains unaddressed is the value appropriation aspect of such activities. We introduce a multilevel theory and maintain that operating regionally through commercialization activities (downstream activities) provides complementary assets to the upstream activities – specifically R&D activities in a country within that region – with which focal firms can appropriate more from their innovations. We find that regional downstream commercialization activities can substitute for weak IPR regimes, thereby providing firms with an alternative mechanism for protecting their intellectual property in weak IPR countries.     

Corporate Political Activities and the SEC's Oversight Role in the IPO Process

We study how a regulator (Securities and Exchanges Commission; SEC) responds to IPOs that have a higher political profile. We find that IPOs with issuers (intermediaries) that actively pursue political strategies receive more (less) SEC comment letters than IPOs without such actors. Cross-sectional analysis reveals that the IPO's political environment moderates the relationship between social pressure for more corporate transparency and SEC scrutiny. Additional tests indicate that the political activities of issuers (intermediaries) contribute to a less (more) efficient IPO process. Overall, our findings suggest that politically active intermediaries have stronger incentives to accurately portray the IPO financial reporting environment than politically active issuers because they have greater reputational and political capital at stake; quite simply, the former have more to lose. We draw out the implications for theory, in terms of agency and reputation.     

Use of a Markov decision process model for treatment selection in an asymptomatic disease with consideration of risk sensitivity

Some potentially dangerous diseases are completely asymptomatic. Their diagnosis as incidental findings of ever-more-sensitive medical imaging can leave patients and physicians in something of a quandary. The patient feels well, and potential interventions to stave off long-term deterioration or death bring with them immediate risks. We discuss the use of a Markov Decision Process (MDP) model (rather than Monte Carlo simulation of a Markov Model) to create a tool for analyzing individual treatment decisions for asymptomatic chronic diseases where a patient’s condition cannot improve. We formulate a finite-horizon MDP model to determine optimal treatment plans and discuss three distinct optimality criteria: (a) maximizing expected quality-adjusted-life years with and without discounting, (b) maximizing the expected number of life years in good health, and (c) maximizing the expected utility for number of years in good health. In (c) we assume exponential utility and consider different risk aversion factors reported in the medical literature. We illustrate the model’s use by considering asymptomatic intracranial aneurysm. Our model builds on a simulation model [19] created to examine treatment recommendations based on cost-effectiveness. We demonstrate that incorporating risk aversion leads to “no treatment” recommendations for some types of aneurysm. Furthermore, the use of alternate patient-selected criteria leads to recommendations that vary from [19] in several scenarios. We also discuss the use of the software as a decision support tool to help make individualized treatment recommendations and demonstrate that the computational performance of the algorithm makes its use feasible during a short office visit.     

Price uncertainty, saving, and welfare

We analyze how commodity price uncertainty affects saving behavior and welfare in a dynamic model with multiple commodities, portfolio hedging, and a preference structure that disentangles ordinal preferences, attitudes towards risk, and attitudes towards intertemporal substitution. We show that the effect of price uncertainty on savings boils down to knowing (1) hf degree of resistance to intertemporal substitution and (2) the effect that uncertainty has on the certainty-equivalent real interest rate. We also show that, if the certainty-equivalent real interest rate is lower with uncertainty, consumers' welfare is also lower.     

A preliminary exploration of the effects of rational factors and behavioral biases on the managerial choice to invest in corporate responsibility

We explore a possible decision‐making process in which mixes of rational and non‐rational factors affect the choice made by a firm's management to invest in corporate responsibility. We propose that the rational factors affecting the decision‐makers' investment choice are: (a) moral choice; (b) risk management; (c) consequential changes that would be required in corporate structure or production processes; and (d) long‐term versus short‐term considerations. The non‐rational behavioral biases that we suggest affecting the decision‐makers' investment choice are: (a) attitude to risk, (b) status quo bias, (c) subjective discounting, and (d) myopic loss‐aversion. Copyright © 2011 John Wiley & Sons, Ltd.     

Innovating Beyond the Horizon: CEO Career Horizon,Top Management Composition,and R&D Intensity

Decreasing research and development (R&D) can impair the ability of firms to remain innovative in the long run. CEOs have been accused of curtailing R&D investments as they approach expected retirement, yet received findings on R&D investment behaviors of late‐career CEOs are mixed. We argue that one reason for these inconsistent findings could be that traditional approaches overlook the fact that CEOs are not isolated agents in making R&D decisions. We build on the premise that CEOs interact with their top management team (TMT) when shaping R&D strategy and advance a contextualized view of CEO dispositions in their late career stages as being constrained or enabled by their TMT. We hypothesize that some TMT attributes (e.g., tenure and age) may amplify, whereas others (e.g., functional experience and education) may mitigate inclinations to reduce R&D. Our findings, based on a longitudinal sample of 100 US manufacturing firms from 1998 to 2008, provide nuanced insights into how different TMT characteristics influence CEO‐TMT dynamics, with TMT age and TMT tenure playing particularly pronounced roles. We discuss implications of our CEO‐TMT interface approach for theory and practice. © 2015 Wiley Periodicals, Inc.     

Sad-Loser contests

We consider asymmetric winner-reimbursed contests. It turns out that such contests (Sad-Loser) have multiple internal pure-strategy equilibria (where at least two players are active). We describe all equilibria and discuss their properties. In particular, we find (1) that an active player is indifferent among all her non-negative choices and her expected payoff is zero in any internal equilibrium, (2) that a higher-value (stronger) player always spends less than a lower-value (weaker) player and therefore always has a lower chance to win a Sad-Loser contest in any internal equilibrium, and (3) a sufficient condition for a net total spending to be higher in a Sad-Loser contest than in the corresponding asymmetric contest.     

Endogenous debt constraints in collateralized economies with default penalties

The objective of the paper is to propose endogenous debt constraints that rule out Ponzi schemes and ensure the existence of equilibria in a model with limited commitment and (possible) default. We appropriately modify the definition of finitely effective debt constraints, introduced by Levine and Zame (1996) (see also Levine and Zame (2002)), to encompass models with limited commitment, default penalties and collateral. Along this line, we introduce in the setting of Araujo et al. (2002), Kubler and Schmedders (2003) and Páscoa and Seghir (2009) the concept of actions with finite equivalent payoffs. We show that, independent of the level of default penalties, restricting plans to have finite equivalent payoffs rules out Ponzi schemes and guarantees the existence of an equilibrium that is compatible with the minimal ability to borrow and lend that we expect in our model.     

How useful are no-arbitrage restrictions for forecasting the term structure of interest rates?

We develop a general framework for analyzing the usefulness of imposing parameter restrictions on a forecasting model. We propose a measure of the usefulness of the restrictions that depends on the forecaster’s loss function and that could be time varying. We show how to conduct inference about this measure. The application of our methodology to analyzing the usefulness of no-arbitrage restrictions for forecasting the term structure of interest rates reveals that: (1) the restrictions have become less useful over time; (2) when using a statistical measure of accuracy, the restrictions are a useful way to reduce parameter estimation uncertainty, but are dominated by restrictions that do the same without using any theory; (3) when using an economic measure of accuracy, the no-arbitrage restrictions are no longer dominated by atheoretical restrictions, but for this to be true it is important that the restrictions incorporate a time-varying risk premium.     

Explaining the Choice Among Regulatory Plans in the U.S. Telecommunications Industry

We investigate why different states in the United States choose different regulatory plans in their telecommunications industry. We present a simple theoretical model and an empirical analysis of the issue. We find that a state is more likely to replace rate-of-return regulation with incentive regulation when: (1) residential basic local service rates have historically been relatively high; (2) allowed earnings under rate-of-return regulation in the state have been either particularly high or particularly low; (3) the state's leaders tend to come from both major political parties, rather than from a single party; (4) the state's urban population is growing relatively rapidly; and (5) the bypass activity of competitors in the state is less pronounced.     

The competitive effects of line-of-business restrictions in telecommunications

We review the original rationale for the line-of-business restrictions faced by the RBOCs and discuss changes in the conditions that motivated them. These changes include: (1) reduced incentives for local exchange carriers (LECs) to shift costs from unregulated to regulated businesses; (2) improved deterrence and monitoring of discrimination in providing network access; and (3) recognition that antitrust laws apply to abuse of market power in local exchange. We also analyze trends in prices charged by RBOCs and other LECs which suggest that the opportunity to engage in cost shuting is of little or no significance today. We conclude that eliminating the remaining line-of-business restrictions is not likely to raise significant new competitive concerns but consumers are likely to benefit from entry by RBOCs into now-prohibited businesses, many of which are highly concentrated.