Bayesian Inference of Social Norms as Shared Constraints on Behavior

People act upon their desires, but often, also act in adherence to implicit social norms. How do people infer these unstated social norms from others' behavior, especially in novel social contexts? We propose that laypeople have intuitive theories of social norms as behavioral constraints shared across different agents in the same social context. We formalize inference of norms using a Bayesian Theory of Mind approach, and show that this computational approach provides excellent predictions of how people infer norms in two scenarios. Our results suggest that people separate the influence of norms and individual desires on others' actions, and have implications for modelling generalizations of hidden causes of behavior.Comment: 7 pages, 5 figures, to appear in CogSci 2019, code available at https://github.com/ztangent/norms-cogsci1

Pricing Limited Partnerships in the Secondary Market

This study investigates the pattern of prices for multiple partnerships sold in the secondary market. In the model, the partnership buyer prefers to purchase the units sequentially since sellers have varying desires to sell. The benefit of a sequential purchase strategy is partially offset by rational sellers who demand higher prices in earlier sales since the possibility of future sales reduces the sellers’ eagerness to sell in earlier rounds. If this strategic component is sufficiently large, a pattern of decreasing prices should be observed. Using a panel dataset comprised of 52,679 transactions from eighteen real estate limited partnerships, and after controlling for performance characteristics, the study finds that prices decrease over time, thus indicating a significant strategic component in this market.

Plateau-Rayleigh instability in solids is a simple phase separation

A long elastic cylinder, with radius a and shear-modulus μ, becomes unstable given sufficient surface tension γ. We show this instability can be simply understood by considering the energy, E(λ), of such a cylinder subject to a homogenous longitudinal stretch λ. Although E(λ) has a unique minimum, if surface tension is sufficient [Γ≡γ/(aμ)>√32] it loses convexity in a finite region. We use a Maxwell construction to show that, if stretched into this region, the cylinder will phase-separate into two segments with different stretches λ1 and λ2. Our model thus explains why the instability has infinite wavelength and allows us to calculate the instability's subcritical hysteresis loop (as a function of imposed stretch), showing that instability proceeds with constant amplitude and at constant (positive) tension as the cylinder is stretched between λ1 and λ2. We use full nonlinear finite-element calculations to verify these predictions and to characterize the interface between the two phases. Near Γ=√32 the length of such an interface diverges, introducing a new length scale and allowing us to construct a one-dimensional effective theory. This treatment yields an analytic expression for the interface itself, revealing that its characteristic length grows as lwall∼a/√Γ−√32.C.X. thanks the China Scholarship Council and the EPSRC for funding

Endorepellin remodels the endothelial transcriptome toward a pro-autophagic and pro-mitophagic gene signature.

Regulation of autophagy by proteolytically cleaved fragments of heparan sulfate proteoglycans is a novel and current research focus in tumor biology. Endorepellin is the C-terminal angiostatic fragment of the heparan sulfate proteoglycan perlecan and induces autophagy in endothelial cells. To further investigate this property, we used NanoString, a digital PCR platform for measuring pre-defined transcripts in biological samples to analyze a custom subset of 95 autophagy-related genes in human umbilical vein endothelial cells treated with ultrapure human recombinant endorepellin. We discovered an endorepellin-evoked pro-autophagic and pro-mitophagic gene expression signatures, which included two coordinately up-regulated mitochondrial-associated genes encoding the E3 ubiquitin protein ligase Parkin and the tumor suppressor mitostatin. Induction of both proteins required the tyrosine kinase activity of vascular endothelial growth factor receptor 2 (VEGFR2). Furthermore, we discovered that endorepellin evoked mitochondrial depolarization in endothelial cells via a specific interaction between its two proximal LG1/2 domains and VEGFR2. We also found that following loss of membrane potential, mitostatin and parkin interact and that mitostatin associates with the established Parkin receptor mitofusin-2. In conclusion, we have identified a critical role for endorepellin in remodeling the autophagic transcriptome and influencing mitochondrial homeostasis

Mechanisms and solutions to the brittle solder joint in electroless Ni plating

Brittle solder joints in Electroless Ni electroless Pd immersion Au (ENEPIG) surface finishes are one of the key reliability issues in electronics assembly. Previous characterization of the reflow process has indicated that interfacial voids formed after solder reflow are responsible for the decreases in solder joint strength. However, the mechanisms behind the formation of these voids in the ENEPIG process remain unclear. In this paper, the interaction between various aspects of the ENEPIG process and solder joint strength were investigated. Surface roughness, morphology, and nano-pitting at the interface between electroless Pd and Ni-P were characterized. The size and density of nano voids inside Ni2SnP were measured after the specimens were reflowed with Sn4Ag0·5Cu solder ball. Additionally, high speed shear solder joint strength measurements were made. The results indicated that anion adhesion induced nano-pitting at the interface between the Ni2SnP intermetallic and Pd, resulting in the formation of a nano void layer during reflow. These interfacial voids lead to lower solder joint strength. Based on the results, a solution to prevent the brittle solder joint failures is suggested

Ownership structure and financial constraints: Evidence from a structural estimation

This article examines the impact of the divergence between corporate insiders' control rights and cash-flow rights on firms' external finance constraints via generalized method of moments estimation of an investment Euler equation. Using a large sample of U.S. firms during the 1994–2002 period, we find that the shadow value of external funds is significantly higher for companies with a wider insider control-ownership divergence, suggesting that companies whose corporate insiders have larger excess control rights are more financially constrained. The effect of insider excess control rights on external finance constraints is more pronounced for firms with higher degrees of informational opacity and for firms with financial misreporting, and is moderated by institutional ownership. The results show that the agency problems associated with the control-ownership divergence can have a real impact on corporate financial and investment outcomes.postprin