Anticipated versus inferred politeness

A number of researchers have recently argued that politeness is not always inferred in the form of an implicature as claimed by Brown and Levinson (1987), but rather can be anticipated by addressees when it involves expected behaviour. The distinction between anticipated and inferred politeness is thus an important area for further development of politeness theory. In this paper, the way in which the notion of ‘expectations’ is related to politeness is first considered, before outlining the distinction between anticipated and inferred politeness in some detail. It is then argued that discourse politeness theory (Usami, 1998, 2001a, b, 2002) shows greater promise for deepening our understanding of this distinction than the proposals made thus far by relevance theorists. It is concluded that any investigation of the distinction between anticipating and inferring politeness must ultimately be grounded in empirical studies of politeness phenomena

Scenario analysis for derivatives portfolios via dynamic factor models

A classic approach to financial risk management is the use of scenario analysis to stress test portfolios. In the case of an S&P 500 options portfolio, for example, a scenario analysis might report a P&L of −1m in the event the S&P 500 falls 5% and its implied volatility surface increases by 3 percentage points. But how accurate is this reported value of −1m? Such a number is typically computed under the (implicit) assumption that all other risk factors are set to zero. But this assumption is generally not justified as it ignores the often substantial statistical dependence among the risk factors. In particular, the expected values of the non-stressed factors conditional on the values of the stressed factors are generally non-zero. Moreover, even if the non-stressed factors were set to their conditional expected values rather than zero, the reported P&L might still be inaccurate due to convexity effects, particularly in the case of derivatives portfolios. A further weakness of this standard approach to scenario analysis is that the reported P&L numbers are generally not back-tested so their accuracy is not subjected to any statistical tests. There are many reasons for this but perhaps the main one is that scenario analysis for derivatives portfolios is typically conducted without having a probabilistic model for the underlying dynamics of the risk factors under the physical measure P. In this paper we address these weaknesses by embedding the scenario analysis within a dynamic factor model for the underlying risk factors. Such an approach typically requires multivariate state-space models that can model the real-world behavior of financial markets where risk factors are often latent, and that are sufficiently tractable so that we can compute (or simulate from) the conditional distribution of unstressed risk factors. We demonstrate how this can be done for observable as well as latent risk factors in examples drawn from options and fixed income markets. We show how the two forms of scenario analysis can lead to dramatically different results particularly in the case of portfolios that have been designed to be neutral to a subset of the risk factors

Spatial Analysis of 3′ Phosphoinositide Signaling in Living Fibroblasts: II. Parameter Estimates for Individual Cells from Experiments

AbstractFibroblast migration is directed by gradients of platelet-derived growth factor (PDGF) during wound healing. As in other chemotactic systems, it has been shown recently that localized stimulation of intracellular phosphoinositide (PI) 3-kinase activity and production of 3′ PI lipids in the plasma membrane are important events in the signaling of spatially biased motility processes. In turn, 3′ PI localization depends on the effective diffusion coefficient, D, and turnover rate constant, k, of these lipids. Here we present a systematic and direct comparison of mathematical model calculations and experimental measurements to estimate the values of the effective 3′ PI diffusion coefficient, D, turnover rate constant, k, and other parameters in individual fibroblasts stimulated uniformly with PDGF. In the context of our uniform stimulation model, the values of D and k in each cell were typically estimated within 10–20% or less, and the mean values across all of the cells analyzed were D=0.37±0.25μm2/s and k=1.18±0.54min−1. In addition, we report that 3′ PI turnover is not affected by PDGF receptor signaling in our cells, allowing us to focus our attention on the regulation of 3′ PI production as this system is studied further

When formal institutions impede entrepreneurship: how and why refugees establish new ventures in the Dadaab refugee camps

For this paper we investigated refugee entrepreneurship in the Dadaab refugee camps, Kenya, a place where humanitarian aid practices and domestic legislation impede entrepreneurship, yet hundreds of new ventures have been established by refugees. The analysis finds that refugee camp entrepreneurs erode formal institutions, recombine conducive aspects of both formal and informal institutions, and exploit the advantages of institutional misalignment. We explain how entrepreneurs strategically maintain rather than overcome institutional misalignment for venture creation. Second, we show how self-determination, rather than mere subsistence or necessity, is an important yet often overlooked motivator for entrepreneurship in low and lower middle-income contexts

The advantage of lefties in one-on-one sports

Left-handers comprise approximately 15% of professional tennis players, but only 11% of the general population. In boxing, baseball, fencing, table-tennis and specialist batting positions in cricket the contrast is even starker, with 30% or more of top players often being left-handed. In this paper we propose a model for identifying the advantage of being left-handed in one-on-one interactive sports (as well as the inherent skill of each player). We construct a Bayesian latent ability model in the spirit of the classic Glicko model but with the additional complication of having a latent factor, i.e. the advantage of left-handedness, that we need to estimate. Inference is further complicated by the truncated nature of data-sets that arise from only having data of the top players. We show how to infer the advantage of left-handedness when only the proportion of top left-handed players is available. We use this result to develop a simple dynamic model for inferring how the advantage of left-handedness varies through time. We also extend the model to cases where we have ranking or match-play data. We test these models on 2014 match-play data from top male professional tennis players, and the dynamic model on data from 1985 to 2016

Common property: uncommon forms of prosocial organizing

As Adam Smith memorably observed, commerce is replete with positive externalities (Smith, 1776). Much good comes to societies in which profit-seeking entrepreneurship flourishes, including gainful employment and the generation of income for expenditure on life’s necessities and luxury goods and services. Alas, the externalities are not always positive and individuals, groups and societies also suffer from the negative externalities of commerce. Lately there has been heightened concern that left to its own self-interested devices, commerce is responsible for increasing social and environmental harm. Porter and Kramer (2011) remark that “business increasingly has been viewed as a major cause of social, environmental, and economic problems. Companies are widely perceived to be prospering at the expense of the broader community” (p. 62)

Multifrequency Eddy Current Clad Thickness Measurement of Thin Aluminum Alloy Combinations Having Similar Conductivities

Clad materials can offer several performance advantages over unclad materials including better corrosion resistance, increased mechanical wear, improved joining qualities, and enhanced metallurgical properties. Clad materials are used extensively in automotive and building products, aerospace applications, and air conditioning equipment. Clad products pose special production problems due to their unique composition. These products might require clad on one or both sides and, depending on the product, the clad and core alloys come in several combinations. For proper process and quality control, products are required to be sampled to ensure that the clad layer is within a certain tolerance band for maximum and minimum thickness. The eddy current method described here can be employed to make a rapid, nondestructive determination of the clad thickness

Quantitative elucidation of a distinct spatial gradient-sensing mechanism in fibroblasts

Migration of eukaryotic cells toward a chemoattractant often relies on their ability to distinguish receptor-mediated signaling at different subcellular locations, a phenomenon known as spatial sensing. A prominent example that is seen during wound healing is fibroblast migration in platelet-derived growth factor (PDGF) gradients. As in the well-characterized chemotactic cells Dictyostelium discoideum and neutrophils, signaling to the cytoskeleton via the phosphoinositide 3-kinase pathway in fibroblasts is spatially polarized by a PDGF gradient; however, the sensitivity of this process and how it is regulated are unknown. Through a quantitative analysis of mathematical models and live cell total internal reflection fluorescence microscopy experiments, we demonstrate that PDGF detection is governed by mechanisms that are fundamentally different from those in D. discoideum and neutrophils. Robust PDGF sensing requires steeper gradients and a much narrower range of absolute chemoattractant concentration, which is consistent with a simpler system lacking the feedback loops that yield signal amplification and adaptation in amoeboid cells