Smoothness for Simultaneous Composition of Mechanisms with Admission

We study social welfare of learning outcomes in mechanisms with admission. In our repeated game there are $n$ bidders and $m$ mechanisms, and in each round each mechanism is available for each bidder only with a certain probability. Our scenario is an elementary case of simple mechanism design with incomplete information, where availabilities are bidder types. It captures natural applications in online markets with limited supply and can be used to model access of unreliable channels in wireless networks. If mechanisms satisfy a smoothness guarantee, existing results show that learning outcomes recover a significant fraction of the optimal social welfare. These approaches, however, have serious drawbacks in terms of plausibility and computational complexity. Also, the guarantees apply only when availabilities are stochastically independent among bidders. In contrast, we propose an alternative approach where each bidder uses a single no-regret learning algorithm and applies it in all rounds. This results in what we call availability-oblivious coarse correlated equilibria. It exponentially decreases the learning burden, simplifies implementation (e.g., as a method for channel access in wireless devices), and thereby addresses some of the concerns about Bayes-Nash equilibria and learning outcomes in Bayesian settings. Our main results are general composition theorems for smooth mechanisms when valuation functions of bidders are lattice-submodular. They rely on an interesting connection to the notion of correlation gap of submodular functions over product lattices.Comment: Full version of WINE 2016 pape

Justificative conformity in ontologically ring-fenced fields: Problematizing the scholarly nomenclature in qualitative studies

Ontology is implicitly or explicitly the impetus of any study. However, what are the implications of a scholarly field whose prevailing ontological assumptions and resultant epistemological commitments impede more nuanced theorizing? In this paper, we caution against theorizing norms in fields characterized by a non-diverse and non-inclusive set of ontological assumptions. We contend that editorial practices therein create a certain kind of methodological conformity and conduct, that is, an undue justification and explanatory overtones related to methods that are set against the predominant grain. Through a thematic review of qualitative papers in international marketing as a case in point, we argue against narrow onto-epistemological arsenals, we discuss the value of critical theorizing and put forward two modest proposals to address this kind of scholarly conformity in the future

Assessing the Generalisability of Managerial Discretion:An Empirical Investigation in the Arab World

The purpose of this paper is to examine the generalizability of national-level managerial discretion and to assess whether the national context play a role in changing mainstream research findings. Based on a sample of three Arabian countries and using a panel of prominent cross-cultural scholars who provided 138 discretion scores for the sampled countries, we replicate the national framework of Crossland and Hambrick (2011) in a new cultural context. The cultural dimensions were measured via survey responses of 375 middle-managers based on House et al. (2004) cultural practices scale. Consistent with Crossland and Hambrick (2011), we demonstrate that individualism and uncertainty tolerance have the same positive effect on CEOs discretion even in a different cultural setting. In contrast, we show that power distance has a positive and significant effect on managerial discretion. Our results indicate that executives can take idiosyncratic and bold actions to the extent to which the cultural environment allows them to do so. Accordingly, we contribute by showing the importance of the national setting in affecting the generalizability of discretion findings

Strategizing in a Focused Context:Managerial Discretion in the Arab World

The purpose of our study is to broaden the national-level construct of managerial discretion and to investigate the effect of cultural practices on executive discretion. Based on a sample of six Arabian countries and using a panel of prominent cross-cultural scholars who provided 262 discretion scores for the sample countries, we replicate and extend the national framework of Crossland and Hambrick (2011) in a new cultural context. The cultural dimensions were measured using survey responses of middle-managers based on House et al. (2004) cultural practices scale. We extend the national-level framework of managerial discretion and find that an encompassing array of cultural practices play a crucial role in shaping the degree of discretion provided to CEOs. We empirically demonstrate that power distance, future and performance orientation along with gender egalitarianism and assertiveness has positive relationships with managerial discretion. However, institutional collectivism, uncertainty avoidance and humane orientation negatively affect the degree of discretion provided to CEOs. Our study fills a gap in the literature regarding the national-level framework of managerial discretion. Our results indicate that executives can take idiosyncratic and bold actions to the extent to which the cultural environment allows them to do so. Also, we discover new national-level antecedents of managerial discretion that haven’t been considered in earlier studies and confirm the context dependency of this concept

Coarse Brownian Dynamics for Nematic Liquid Crystals: Bifurcation Diagrams via Stochastic Simulation

We demonstrate how time-integration of stochastic differential equations (i.e. Brownian dynamics simulations) can be combined with continuum numerical bifurcation analysis techniques to analyze the dynamics of liquid crystalline polymers (LCPs). Sidestepping the necessity of obtaining explicit closures, the approach analyzes the (unavailable in closed form) coarse macroscopic equations, estimating the necessary quantities through appropriately initialized, short bursts of Brownian dynamics simulation. Through this approach, both stable and unstable branches of the equilibrium bifurcation diagram are obtained for the Doi model of LCPs and their coarse stability is estimated. Additional macroscopic computational tasks enabled through this approach, such as coarse projective integration and coarse stabilizing controller design, are also demonstrated

Phase-Transition Theory of Instabilities. II. Fourth-Harmonic Bifurcations and Lambda-Transitions

We use a free-energy minimization approach to describe the secular and dynamical instabilities as well as the bifurcations along equilibrium sequences of rotating, self-gravitating fluid systems. Our approach is fully nonlinear and stems from the Ginzburg-Landau theory of phase transitions. In this paper, we examine fourth-harmonic axisymmetric disturbances in Maclaurin spheroids and fourth-harmonic nonaxisymmetric disturbances in Jacobi ellipsoids. These two cases are very similar in the framework of phase transitions. Irrespective of whether a nonlinear first-order phase transition occurs between the critical point and the higher turning point or an apparent second-order phase transition occurs beyond the higher turning point, the result is fission (i.e. ``spontaneous breaking'' of the topology) of the original object on a secular time scale: the Maclaurin spheroid becomes a uniformly rotating axisymmetric torus and the Jacobi ellipsoid becomes a binary. The presence of viscosity is crucial since angular momentum needs to be redistributed for uniform rotation to be maintained. The phase transitions of the dynamical systems are briefly discussed in relation to previous numerical simulations of the formation and evolution of protostellar systems.Comment: 34 pages, postscript, compressed,uuencoded. 7 figures available in postscript, compressed form by anonymous ftp from asta.pa.uky.edu (cd /shlosman/paper2 mget *.ps.Z). To appear in Ap

How Formal and Informal Institutions of Middle Eastern Countries Influence Managerial Discretion: An Empirical Investigation

Managerial discretion is the focal theme bridging the clash between two schools of thoughts; whether executives have greater influence on their firms’ outcomes or other factors restrain their actions (Hambrick & Finkelstein, 1987). It is argued that constraints come from inertial, normative and environmental forces (e.g. DiMaggio & Powell, 1983). Of these restraints is the institutional environment in which a firm is headquartered. Our paper falls within this research stream and provides an extension for Crossland and Hambrick (2007, 2011) work. We investigate the national level of discretion in new cross-cultural contexts, provide deeper understanding of its concept, and shed the light on undiscovered discretion’s antecedents and consequences. We adopt a quantitative approach in which questionnaires represent our data collection instrument. We anticipate that in high discretion countries firms tend to follow what Miles & Snow (1978) labeled ‘Prospector’ strategy as opposed to low discretion countries in which firms incline to implement a ‘Defender’ strategy

Exact solution for scalar field collapse

We give an exact spherically symmetric solution for the Einstein-scalar field system. The solution may be interpreted as an inhomogeneous dynamical scalar field cosmology. The spacetime has a timelike conformal Killing vector field and is asymptotically conformally flat. It also has black or white hole-like regions containing trapped surfaces. We describe the properties of the apparent horizon and comment on the relevance of the solution to the recently discovered critical behaviour in scalar field collapse.Comment: 10 pages(Latex) (2 figures available upon request), Alberta-Thy-4-9

The Great Pretenders Among the ULX Class

The recent discoveries of pulsed X-ray emission from three ultraluminous X-ray (ULX) sources have finally enabled us to recognize a subclass within the ULX class: the great pretenders, neutron stars (NSs) that appear to emit X-ray radiation at isotropic luminosities $L_X = 7\times 10^{39}$~erg~s$^{-1}-1\times 10^{41}$~erg~s$^{-1}$ only because their emissions are strongly beamed toward our direction and our sight lines are offset by only a few degrees from their magnetic-dipole axes. The three known pretenders appear to be stronger emitters than the presumed black holes of the ULX class, such as Holmberg II \& IX X-1, IC10 X-1, and NGC300 X-1. For these three NSs, we have adopted a single reasonable assumption, that their brightest observed outbursts unfold at the Eddington rate, and we have calculated both their propeller states and their surface magnetic-field magnitudes. We find that the results are not at all different from those recently obtained for the Magellanic Be/X-ray pulsars: the three NSs reveal modest magnetic fields of about 0.3-0.4~TG and beamed propeller-line X-ray luminosities of $\sim 10^{36-37}$~erg~s$^{-1}$, substantially below the Eddington limit.Comment: To appear in Research in Astronomy and Astrophysic