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

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

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

Does maternity leave affect child health? Evidence from parental leave in Australia survey

One of the arguments that is advanced in support of paid maternity leave (PML) policies is that the mother’s time away from work, around childbirth, is expected to improve maternal health and child health and development. However evidence on these links is scarce and, until recently, little was known about the link, if any, between child health and maternity leave. Moreover, the limited literature that does exist tends to use aggregate data (i.e., an “ecological design”) to test the hypotheses that maternity leave affects maternal and child health. Evidence from micro-level data is rare because of the unavailability of such data on household level. We employ such data from the Parental Leave in Australia Survey (PLAS), which is a nested survey of the Longitudinal Study of Australian Children (LSAC), to examine the impacts of maternity leave on child health. Using the PLAS and the first two waves of the LSAC we find that maternity leave, as measured by the duration of paid maternity leave (PML) and other forms of leave around childbirth, have strong and statistically significant effects on: child health, the decision to breastfeed, the duration of breastfeeding, and the probability that child immunisations are up-to-date. Our results show that mothers who take maternity leave are more likely to breastfeed their children and also that longer-term maternity leave is associated with an increase in the duration of breastfeeding. Our results also confirm that both mothers’ PML and fathers’ paid paternity leave (PPL) have statistically significant and positive effects on general health status of children. We also find that, in most specifications, the effects of PML are significant if the duration of leave is at least 6 weeks. PML is also significantly associated with a lower probability of some childhood chronic conditions such as asthma and bronchiolitis, but the effects of PPL on these conditions is ambiguous

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.

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

Structural Development, Strain History, and Timing of Deformation in the Eastern Great Smoky Mountains

The present investigation reveals that the Greenbrier and Dunn Creek thrust sheets preserve well-formed ramp-related folds within the Great Smoky Mountains area. The Greenbrier thrust sheet preserves a ramp anticline at klippes of the Greenbrier thrust sheet in the eastern Great Smoky Mountains that can be traced discontinuously to the western Great Smoky Mountains where this anticline has been modified by later displacement along the Rabbit Creek fault. A ramp-related fold is also preserved in the main Greenbrier thrust sheet. The main Greenbrier fault was subsequently folded by an underlying ramp anticline within the Dunn Creek thrust sheet. These earliest thrust systems have therefore been reconstructed based on foreland models of ramps and flats. The thrust faults form a folded imbricate fan structure with lower hanging-wall ramp anticlines folding higher thrust sheets. The foreland-style thrust system was internally deformed later in the Taconic during emplacement of a thrust sheet now floored by the Miller Cove fault. The Taconic package if imbricated Ocoee strata was emplaced onto the Valley and Ridge during the Alleghanian orogeny by the late Miller Cove and Great Smoky thrust systems. Faults in these late systems occupied various parts of the early ductile thrust zones, and almost certainly excised significant lower parts of the three early thrust sheets. Internal strain within sandstones of the Miller Cove, Dunn Creek, and Greenbrier thrust sheets was also investigated. The three-dimensional finite strain geometry was determined for 69 samples using the Rf/ø and normalized Fry methods. Microstructural observations indicate that strains were accommodated by those deformation mechanisms typical of low grade metamorphic conditions including dislocation flow (undulatory extinction, deformation lamellae, deformation bands, patchy extinction, serrated grain boundaries), pressure solution (stylolites, sutured grain boundaries, overgrowths), and brittle fracturing (microfractures, fluid inclusion planes). Finite strains recorded within the sandstones are low and generally increase toward the hinterland (to the south). Mean X/Z strain ratios determined by the Rf/ø method for the Miller Cove, Dunn Creek, and Greenbrier thrust sheets are 1.29, 1.32, and 1.42, respectively. X/Z ratios determined using the Fry method are typically 5 to 20 percent higher. Principal strain axes within all thrust sheets exhibit subhorizontal strike-parallel X axes, subhorizontal transport-parallel Y axes, and steeply northwest plunging Z axes. Within hanging-wall ramp portions of the Dunn Creek thrust sheet, however, most X axes are parallel to transport and Y axes are parallel to strike. Two models were evaluated by strain factorization in an attempt to produce a sequence of strain events compatible with the finite strains observed in the two structural domains (hanging-wall flat and hanging-wall ramp). The first model involves compaction, layer-parallel shortening/extension, and simple shear. The second model is identical to the first with the exception of the addition of 90 degree rigid-body rotation following compaction to simulate sample from the hanging-wall ramp portions of the Dunn Creek thrust sheet. A sequence of strain events modeled by strain factorization, including 20 percent compaction, layer-parallel shortening of 5 percent, and thrust-parallel simple shear of 0.1, can produce the measured finite strains in the hanging-wall flat areas. The finite strains within the hanging-wall ramp portion of the Dunn Creek thrust sheet, however, require a different strain sequence, including 20 percent compaction by volume loss, 90 degree rigid body rotation following compaction, 20 to 30 percent horizontal extension, and a simple shear. The failure of a single model to account for observed finite strains in the two subdomains may be explained by: 1) Incorrectly assuming a single homogeneous strain across both subdomains; 2) The absence of compaction strains, although this would require another model to explain finite strains in the first subdomain; 3) Samples from the hanging-wall ramp area may yield unreliable results because of their fine-grained and matrix-rich compositions; or 4) The simplicity of the strain model, which assumes vertical bedding in the hanging-wall ramp where the average dip is 48 degrees and beds are overturned. The importance of Ordovician tectonothermal activity in the western Blue Ridge of the southern Appalachians has been questioned by recent reports of Late Devonian-earliest Mississippian fossils within regionally metamorphosed rocks. In addition, metamorphism of fossiliferous Early Devonian rocks within the Talladega belt and suggested stratigraphic correlations with rocks of the Murphy belt suggest only post-Silurian metamorphism. The recent reports are contrary to most previous geochronology that suggests Ordovician metamorphism, as well as stratigraphic evidence indicating a Late Proterozoic age for most western Blue Ridge protoliths. To evaluate these contradictory results, eleven whole-rock samples (chlorite to garnet zones) and three muscovite concentrates (staruolite and kyanite zones) from the eastern Great Smoky Mountains of the western Blue Ridge were analyzed with 40Ar/39Ar techniques. Most chlorite-grade sample record plateau and intermediate temperature ages of 440 to 460 Ma. Illite crystallinity characteristics indicate that these samples attained metamorphic conditions sufficient for complete rejuvenation of whole-rock systems. Most biotite- and garnet-grade whole-rock samples yield plateau and intermediate temperature ages of 340 to 350 Ma. Muscovite samples record plateau ages of 360 to 380 Ma. It is unlikely that whole-rock samples collected several kilometers apart could have experienced contrasting cooling histories resulting in 100 Ma differences in apparent age. Therefore, the 40Ar/39Ar results most likely indicate a polymetamorphic history in which a 440 to 460 Ma (Middle to Late Ordovician) event was overprinted by a 360 to 380 Ma (Middle to Late Devonian) event. This interpretation is consistent with metamorphic textures observed in the western Blue Ridge

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

A practical office procedure for the reduction of the potential transmission of AIDS in the contact lens practice

This paper presents a proposed standardized protocol for the efficient and economical large scale cleaning and disinfection of both soft and rigid contact lenses. In recent years, there has been an increased concern about the possibility of transmitting pathogenic agents via contact lenses. This protocol is primarily concerned with the risks associated with the acquired immunodeficiency syndrome (AIDS) virus in the general population. The AIDS virus represents a significant risk that must be addressed because of the consequences of contracting the virus and its isolation from the tears of human immunodeficiency virus (HIV) positive individuals