The Endowment Effect in a Public Good Experiment

Previous tests of the endowment effect have usually observed WTA-WTP disparities. Here, a public good experiment is employed. Both account framing and duration framing treatments are introduced to alter subjects’ perceived control over an initial endowment. Results do not indicate that preferences shift in a way consistent with the endowment effect.endowment effect, public good, willingness to pay

Price Level Convergence Among United States Cities: Lessons for the European Central Bank

We study the dynamics of price indices for major U.S. cities using panel econometric methods and find that relative price levels among cities mean revert at an exceptionally slow rate. In a panel of 19 cities from 1918 to 1995, we estimate the half-life of convergence to be approximately nine years. These estimates provide an upper bound on speed of convergence that participants in European Monetary Union are likely to experience. The surprisingly slow rate of convergence can be explained by a combination of the presence of transportation costs, differential speeds of adjustment to small and large shocks, and the inclusion of non-traded good prices in the overall price index.

Sphaerodactylus fantasticus

Number of Pages: 8Integrative BiologyGeological Science

The stoichiometry of P2X2/6 receptor heteromers depends on relative subunit expression levels

Fast synaptic transmission involves the operation of ionotropic receptors, which are often composed of at least two types of subunit. We have developed a method, based on atomic force microscopy imaging to determine the stoichiometry and subunit arrangement within ionotropic receptors. We showed recently that the P2X(2) receptor for ATP is expressed as a trimer but that the P2X(6) subunit is unable to oligomerize. In this study we addressed the subunit stoichiometry of heteromers containing both P2X(2) and P2X(6) subunits. We transfected tsA 201 cells with both P2X(2) and P2X(6) subunits, bearing different epitope tags. We manipulated the transfection conditions so that either P2X(2) or P2X(6) was the predominant subunit expressed. By atomic force microscopy imaging of isolated receptors decorated with antiepitope antibodies, we demonstrate that when expression of the P2X(2) subunit predominates, the receptors contain primarily 2 x P2X(2) subunits and 1 x P2X(6) subunit. In contrast, when the P2X(6) subunit predominates, the subunit stoichiometry of the receptors is reversed. Our results show that the composition of P2X receptor heteromers is plastic and dependent on the relative subunit expression levels. We suggest that this property of receptor assembly might introduce an additional layer of subtlety into P2X receptor signaling

Eurasian watermilfoil biomass associated with insect herbivores in New York

A study of aquatic plant biomass within Cayuga Lake, New York spans twelve years from 1987-1998. The exotic Eurasian watermilfoil ( Myriophyllum spicatum L.) decreased in the northwest end of the lake from 55% of the total biomass in 1987 to 0.4% in 1998 and within the southwest end from 50% in 1987 to 11% in 1998. Concurrent with the watermilfoil decline was the resurgence of native species of submersed macrophytes. During this time we recorded for the first time in Cayuga Lake two herbivorous insect species: the aquatic moth Acentria ephemerella , first observed in 1991, and the aquatic weevil Euhrychiopsis lecontei , first found in 1996 . Densities of Acentria in southwest Cayuga Lake averaged 1.04 individuals per apical meristem of Eurasian watermilfoil for the three-year period 1996-1998. These same meristems had Euhrychiopsis densities on average of only 0.02 individuals per apical meristem over the same three-year period. A comparison of herbivore densities and lake sizes from five lakes in 1997 shows that Acentria densities correlate positively with lake surface area and mean depth, while Euhrychiopsis densities correlate negatively with lake surface area and mean depth. In these five lakes, Acentria densities correlate negatively with percent composition and dry mass of watermilfoil. However, Euhrychiopsis densities correlate positively with percent composition and dry mass of watermilfoil. Finally, Acentria densities correlate negatively with Euhrychiopsis densities suggesting interspecific competition

The Likely Impact of National Federation on Commerce Clause Jurisprudence

In National Federation of Independent Businesses v. Sebelius, the Supreme Court exhaustively analyzed Congress’s constitutional power to enact the watershed Patient Protection and Affordable Care Act (ACA or “Obamacare”). The ACA imposes a “shared responsibility requirement,” popularly known as the “Individual Mandate” (IM), which forces Americans to buy medical insurance or pay a “penalty.” The ACA’s text and legislative history, as well as the public defenses of it by President Obama and his supporters, consistently described the IM as a valid exercise of Congress’s power “[t]o regulate Commerce . . . among the several States.” This reliance on the Commerce Clause was understandable, as it has been interpreted since 1937 as giving Congress virtually plenary authority. Indeed, the modern Court has upheld every federal statute (with two trivial exceptions) after applying an extremely deferential standard of review: Could Congress have had a rational basis for concluding that the activity regulated, taken in the aggregate nationwide, “substantially affects” interstate commerce? This judicially-approved legislation addressed not merely national economic matters, but also seemingly non-commercial subjects like civil rights, crime, the environment, and health and safety. In National Federation, Justices Ginsburg, Breyer, Sotomayor, and Kagan sought to continue this lenient approach by ruling that Congress could reasonably have determined that Americans’ decisions about health insurance (including the failure to obtain it), when added up nationally, substantially affect the interstate economy. However, Chief Justice Roberts and his four conservative Republican colleagues held that the IM had exceeded the bounds of the Commerce Clause, which restricted Congress to regulating interstate commercial “activity”–as contrasted with the IM’s novel attempt to compel Americans who were inactive in a market to buy something they did not want. The Chief Justice then unexpectedly joined the four liberal Democrats in holding that the IM could plausibly be construed as a “tax” on those who did not buy medical insurance and therefore could be sustained under Congress’s power to “Lay and Collect Taxes.” The four dissenters barely concealed their anger at Chief Justice Roberts for switching sides (apparently at the eleventh hour due to intense political pressure) to save Obamacare on dubious Taxing Power grounds. Most Republican legal analysts had a similar reaction. They fretted that the Court had radically altered its Commerce Clause jurisprudence by refusing to defer to Congress’s policy judgments about an important national economic and social issue, which would invite similar challenges. It is impossible to say with any certitude whether such concerns are warranted. It may be that National Federation portends a shift to increasingly aggressive judicial imposition of serious Commerce Clause restraints. On balance, however, history and pragmatism suggest that this case will have a marginal jurisprudential impact. This conclusion rests primarily on the fact that, since the New Deal era, the Court has sustained all major Commerce Clause legislation, which forms the foundation of the modern administrative and social welfare state. Realistically, the Court would risk legal, political, social, and economic chaos by rolling back its precedent allowing such important federal laws. Thus, at most the conservative Justices can try to stem the tide of new Commerce Clause statutes. Yet recent experience suggests that even that modest goal will prove difficult to achieve, as the Rehnquist Court’s lone attempt to enforce an outer boundary on Congress’s power–that it could regulate only subjects that were “commercial” in nature–fizzled out within a decade. Likewise, National Federation’s new “activity” limit will probably have little lasting relevance, for three reasons. First, the ACA represented Congress’s only attempt in over two centuries to use the Commerce Clause to regulate “inactivity,” and there do not appear to be any similar federal statutes in existence or on the horizon. Second, even if Congress were to enact such a law, it would be invalidated only if five conservative Republican Justices happened to be on the Court. Third, the latter restriction on the Commerce Clause did not put a dent in Congress’s overall power, because Chief Justice Roberts peeled off to uphold the ACA through his creative interpretation of the Taxing Power. The Court will likely remain unwilling to strike down non-trivial federal statutes

Scanning Electron Microscopy Methodology for Study of the Pathophysiology of Calcification in Bioprosthetic Heart Valves

Scanning electron microscope (SEM) morphologic analysis combined with energy dispersive characteristic X-ray (EDX) microprobe analysis provides insight into the mechanisms associated with disease-related crystal formation in biological materials. SEM and EDX were employed in analyzing specimens which were embedded in standard fashion in glycolmethacrylate (JB-4). The specimen surfaces under electron microscope investigation resulted from microtomy used in the preparation of reference light microscope histological sections; thus histology served as a direct reference for the SEM and EDX analyses. The particular application of these methods was in the study of bioprosthetic heart valve calcification, largely responsible for clinical failure of these heart valve substitutes. To simulate the clinically observed mineralization processes, glutaraldehyde-pretreated porcine heart valve leaflets were implanted subcutaneously in rats and subsequently removed at various time intervals from 1 to 56 days. Also, to address the hypothesis that the calcification process generates crystalline materials analogous to those in bone, EDX data obtained from pure hydroxyapatite were compared with the embedded tissue results. Further, EDX results were compared with data obtained by chemical analysis of the bulk specimens to assess the validity of the electron microscope technique

Intermediate progenitors support migration of neural stem cells into dentate gyrus outer neurogenic niches.

The hippocampal dentate gyrus (DG) is a unique brain region maintaining neural stem cells (NCSs) and neurogenesis into adulthood. We used multiphoton imaging to visualize genetically defined progenitor subpopulations in live slices across key stages of mouse DG development, testing decades old static models of DG formation with molecular identification, genetic-lineage tracing, and mutant analyses. We found novel progenitor migrations, timings, dynamic cell-cell interactions, signaling activities, and routes underlie mosaic DG formation. Intermediate progenitors (IPs, Tbr2+) pioneered migrations, supporting and guiding later emigrating NSCs (Sox9+) through multiple transient zones prior to converging at the nascent outer adult niche in a dynamic settling process, generating all prenatal and postnatal granule neurons in defined spatiotemporal order. IPs (Dll1+) extensively targeted contacts to mitotic NSCs (Notch active), revealing a substrate for cell-cell contact support during migrations, a developmental feature maintained in adults. Mouse DG formation shares conserved features of human neocortical expansion

Some Examples of the Applications of the Transonic and Supersonic Area Rules to the Prediction of Wave Drag

The experimental wave drags of bodies and wing-body combinations over a wide range of Mach numbers are compared with the computed drags utilizing a 24-term Fourier series application of the supersonic area rule and with the results of equivalent-body tests. The results indicate that the equivalent-body technique provides a good method for predicting the wave drag of certain wing-body combinations at and below a Mach number of 1. At Mach numbers greater than 1, the equivalent-body wave drags can be misleading. The wave drags computed using the supersonic area rule are shown to be in best agreement with the experimental results for configurations employing the thinnest wings. The wave drags for the bodies of revolution presented in this report are predicted to a greater degree of accuracy by using the frontal projections of oblique areas than by using normal areas. A rapid method of computing wing area distributions and area-distribution slopes is given in an appendix