Interpretation of experimental data near lambda-transition point in liquid helium

The recently published experimental data for specific heat C_p of liquid helium in zero gravity conditions very close to the lambda-transition have been discussed. We have shown that these data allow different interpretations. They can be well interpreted within the perturbative RG approach and within our recently developed theory, as well. Allowing the logarithmic correction, the corresponding fits lie almost on top of each other over the whole range of the reduced temperatures t (for bin averaged data) 6.3 x 10^{-10} < t < 8.8 x 10^{-3}. However, the plot of the effective exponent alpha_eff(t) suggests that the behaviour of C_p, probably, changes very close to the lambda-transition temperature. To clarify this question, we need more accurate data for t<10^{-7}. In addition, we show that the experimental data for superfluid fraction of liquid helium close to the critical point within 3 x 10^{-7} < t < 10^{-4} can be better fit by our exponents nu=9/13, Delta=5/13 than by the RG exponents (nu approximately 0.6705 and Delta about 0.5). The latter ones are preferable to fit the whole measured range 3 x 10^{-7} < t < 10^{-2} where, however, remarkable systematic deviations appear. Our estimated value 0.694 +/- 0.017 of the asymptotic exponent nu well agrees with the theoretical prediction nu=9/13.Comment: 9 pages, 4 figures. The first version was a preliminary one. Now it is substentially extended and coincides with the published pape

Reducing Inefficiency in Carbon Auctions with Imperfect Competition

We study auctions for carbon licenses, a policy tool used to control the social cost of pollution. Each identical license grants the right to produce a unit of pollution. Each buyer (i.e., firm that pollutes during the manufacturing process) enjoys a decreasing marginal value for licenses, but society suffers an increasing marginal cost for each license distributed. The seller (i.e., the government) can choose a number of licenses to put up for auction, and wishes to maximize the societal welfare: the total economic value of the buyers minus the social cost. Motivated by emission license markets deployed in practice, we focus on uniform price auctions with a price floor and/or price ceiling. The seller has distributional information about the market, and their goal is to tune the auction parameters to maximize expected welfare. The target benchmark is the maximum expected welfare achievable by any such auction under truth-telling behavior. Unfortunately, the uniform price auction is not truthful, and strategic behavior can significantly reduce (even below zero) the welfare of a given auction configuration. We describe a subclass of "safe-price" auctions for which the welfare at any Bayes-Nash equilibrium will approximate the welfare under truth-telling behavior. We then show that the better of a safe-price auction, or a truthful auction that allocates licenses to only a single buyer, will approximate the target benchmark. In particular, we show how to choose a number of licenses and a price floor so that the worst-case welfare, at any equilibrium, is a constant approximation to the best achievable welfare under truth-telling after excluding the welfare contribution of a single buyer

A Reevaluation of the Role of Family in Immigrants' Labor Market Activity: Evidence from a Comparison of Single and Married Immigrants

Previous papers tested the validity of the Family Investment Hypothesis (FIH) among immigrants by comparing the labor market outcomes of immigrant couples and native or mixed couples. Here we propose an alternative test for the FIH which is based on a comparison between married and single immigrants. The logic underlying this alternative method states that if credit constraints are binding, then only married immigrants can cross-finance their investment within the family. In order to overcome potential selection bias that would arise if unobserved characteristics that affect the marital status of the individual also affect his/her labor market outcomes, we construct a difference-in-differences estimator that exploits variation in the labor market outcomes of married and single natives. Implementation of this method using US and Israeli data leads to a rejection of the FIH in both countries.family investment model, labor supply

Managed Care and Mental Health: Clinical Perspectives and Legal Realities

Managed care is beginning to dominate the delivery of mental health services. The Article reviews limitations on managed care\u27s ability to deal adequately with mental illness. It discusses empirical and other research examining the use of primary care providers as gatekeepers and it explores utilization review mechanisms, focusing particularly on providers\u27 responses to UR. The impact on quality, access and continuity of care on discrete populations is analyzed. The article then surveys a variety of legal issues in the regulation of managed care, particularly as they apply to the provision of mental health services. These include ERISA, parity and liability questions. The emerging role of accreditation in also reviewed. The essential thesis is that the presence of obvious irrationalities in the delivery of quality mental health services suggests that we are in a transitional era. Legislative, judicial and private initiatives are likely to place significantly greater emphasis in the future on issues of quality control

A Reevaluation Of the Role Of Family In Immigrants' Labor Market Activity;Evidence From a Comparison Of Single and Married Immigrants

Previous papers tested the validity of the Family Investment Hypothesis (FIH) among immigrants by comparing the labor market outcomes of immigrant couples and native or mixed couples. Here we propose an alternative test for the FIH which is based on a comparison between married and single immigrants. The logic underlying this alternative method states that if credit constraints are binding, then only married immigrants can cross-finance their investment within the family. In order to overcome potential selection bias that would arise if unobserved characteristics that affect the marital status of the individual also affect his/her labor market outcomes, we construct a difference-in-differences estimator that exploits variation in the labor market outcomes of married and single natives. Implementation of this method using US and Israeli data leads to a rejection of the FIH in both countries.