The Paternity of the Price-Quality "Value Map"

In the literature on firm strategy and product differentiation, consumer price-quality trade-offs are sometimes represented using consumer “value maps”. These involve the geometric representation of indifferent price and quality combinations as points along curves that are concave to the “quality” axis. In this paper, it is shown that the value map for price-quality tradeoffs may be derived from a Hicksian compensated demand curve for product quality. The paper provides the theoretical link between analytical methods employed in the existing literature on firm strategy and competitive advantage with the broader body of economic analysis.Value map; competitive advantage; quality; price; strategy

The Paternity of the Price-Quality "Value Map"

In the literature on firm strategy and product differentiation, consumer price-quality trade-offs are sometimes represented using consumer “value maps”. These involve the geometric representation of indifferent price and quality combinations as points along curves that are concave to the “quality” axis. In this paper, it is shown that the value map for price-quality tradeoffs may be derived from a Hicksian compensated demand curve for product quality. The paper provides the theoretical link between analytical methods employed in the existing literature on firm strategy and competitive advantage with the broader body of economic analysis

Child Health and the Income Gradient: Evidence from Australia

The positive relationship between household income and child health is well documented in the child health literature but the precise mechanisms via which income generates better health and whether the income gradient is increasing in child age are not well understood. This paper presents new Australian evidence on the child health-income gradient. We use data from the Longitudinal Survey of Australian (LSAC), which involved two waves of data collection for children born between March 2003 and February 2004 (B-Cohort), and between March 1999 and February 2000 (K-Cohort). This data set allows us to test the robustness of some of the findings of the influential studies of Case et al. (2002) and J.Currie and Stabile (2003), and a recent study by A.Currie et al. (2007) , using a sample of Australian children. The richness of the LSAC data set also allows us to conduct further exploration of the determinants of child health. Our results reveal an increasing income gradient by child age using similar covariates to Case et al. (2002). However, the income gradient disappears if we include a rich set of controls. Our results indicate that parental health and, in particular, the mother's health plays a significant role, reducing the income coefficient to zero. Thus, our results for Australian children are similar to those produced by Propper et al. (2007) on their British child cohort. We also find some evidence that higher incomes have a protective effect when health shocks do arise: for several chronic conditions, children from higher-income households are less likely to be reported as being in poor health than children from lower-income households who have the same chronic conditions. The latter result is similar to some recent findings by Condliffe and Link (2008) on a sample of US children.Child health, Income gradient, Parental health, Nutrition, Panel data, Australia

Locked and Unlocked Chains of Planar Shapes

We extend linkage unfolding results from the well-studied case of polygonal linkages to the more general case of linkages of polygons. More precisely, we consider chains of nonoverlapping rigid planar shapes (Jordan regions) that are hinged together sequentially at rotatable joints. Our goal is to characterize the families of planar shapes that admit locked chains, where some configurations cannot be reached by continuous reconfiguration without self-intersection, and which families of planar shapes guarantee universal foldability, where every chain is guaranteed to have a connected configuration space. Previously, only obtuse triangles were known to admit locked shapes, and only line segments were known to guarantee universal foldability. We show that a surprisingly general family of planar shapes, called slender adornments, guarantees universal foldability: roughly, the distance from each edge along the path along the boundary of the slender adornment to each hinge should be monotone. In contrast, we show that isosceles triangles with any desired apex angle less than 90 degrees admit locked chains, which is precisely the threshold beyond which the inward-normal property no longer holds.Comment: 23 pages, 25 figures, Latex; full journal version with all proof details. (Fixed crash-induced bugs in the abstract.

Rigidity and volume preserving deformation on degenerate simplices

Given a degenerate $(n+1)$-simplex in a $d$-dimensional space $M^d$ (Euclidean, spherical or hyperbolic space, and $d\geq n$), for each $k$, $1\leq k\leq n$, Radon's theorem induces a partition of the set of $k$-faces into two subsets. We prove that if the vertices of the simplex vary smoothly in $M^d$ for $d=n$, and the volumes of $k$-faces in one subset are constrained only to decrease while in the other subset only to increase, then any sufficiently small motion must preserve the volumes of all $k$-faces; and this property still holds in $M^d$ for $d\geq n+1$ if an invariant $c_{k-1}(\alpha^{k-1})$ of the degenerate simplex has the desired sign. This answers a question posed by the author, and the proof relies on an invariant $c_k(\omega)$ we discovered for any $k$-stress $\omega$ on a cell complex in $M^d$. We introduce a characteristic polynomial of the degenerate simplex by defining $f(x)=\sum_{i=0}^{n+1}(-1)^{i}c_i(\alpha^i)x^{n+1-i}$, and prove that the roots of $f(x)$ are real for the Euclidean case. Some evidence suggests the same conjecture for the hyperbolic case.Comment: 27 pages, 2 figures. To appear in Discrete & Computational Geometr

Equity of health care financing in Iran

This study presents the rst analyses of the equity of health care financing in Iran. Kakwani Progressivity Indices (KPIs) and concentration indices (CIs) are estimated using ten national household expenditure surveys, which were conducted in Iran from 1995/96 to 2004/05. The indices are used to analyze the progressivity of two sources of health care financing: health insurance premium payments and consumer co-payments (and the sum of these), for Iran as a whole, and for rural and urban areas of Iran, separately. The results suggest that health insurance premium payments became more progressive over the study period; however the KPIs for consumer co-payments suggest that these are still mildly regressive or slightly progressive, depending upon whether household income or expenditure data are used to generate the indices. Interestingly, the Urban Inpatient Insurance Scheme (UIIS), which was introduced by the Iranian government in 2000 to extend insurance to uninsured urban dwellers, appears to have had a regressive impact on health care nancing, which is contrary to expectations. This result sounds a cautionary note about the potential for public programs to crowd out private sector, charitable activity, which was prevalent in Iran prior to the introduction of the UIIS.Equity, Health care nancing, Kakwani progressivity index, Iran

Symmetry as a sufficient condition for a finite flex

We show that if the joints of a bar and joint framework $(G,p)$ are positioned as `generically' as possible subject to given symmetry constraints and $(G,p)$ possesses a `fully-symmetric' infinitesimal flex (i.e., the velocity vectors of the infinitesimal flex remain unaltered under all symmetry operations of $(G,p)$), then $(G,p)$ also possesses a finite flex which preserves the symmetry of $(G,p)$ throughout the path. This and other related results are obtained by symmetrizing techniques described by L. Asimov and B. Roth in their paper `The Rigidity Of Graphs' from 1978 and by using the fact that the rigidity matrix of a symmetric framework can be transformed into a block-diagonalized form by means of group representation theory. The finite flexes that can be detected with these symmetry-based methods can in general not be found with the analogous non-symmetric methods.Comment: 26 pages, 10 figure

Stromal control of oncogenic traits expressed in response to the overexpression of GLI2, a pleiotropic oncogene.

Hedgehog signaling is often activated in tumors, yet it remains unclear how GLI2, a transcription factor activated by this pathway, acts as an oncogene. We show that GLI2 is a pleiotropic oncogene. The overexpression induces genomic instability and blocks differentiation, likely mediated in part by enhanced expression of the stem cell gene SOX2. GLI2 also induces transforming growth factor (TGF)B1-dependent transdifferentiation of foreskin and tongue, but not gingival fibroblasts into myofibroblasts, creating an environment permissive for invasion by keratinocytes, which are in various stages of differentiation having downregulated GLI2. Thus, upregulated GLI2 expression is sufficient to induce a number of the acquired characteristics of tumor cells; however, the stroma, in a tissue-specific manner, determines whether certain GLI2 oncogenic traits are expressed