An inverse modeling approach to obtain P-T conditions of metamorphic stages involving garnet growth and resorption

This contribution presents an approach and a computer program (GRTMOD) for numerical simulation of garnet evolution based on compositions of successive growth zones in natural samples. For each garnet growth stage, a new local effective bulk composition is optimized, allowing for resorption and/or fractionation of previously crystallized garnet. The successive minimizations are performed using the Nelder-Mead algorithm; a heuristic search method. An automated strategy including two optimization stages and one refinement stage is described and tested. This program is used to calculate pressure-temperature (P-T) conditions of crystal growth as archived in garnet from the Sesia Zone (Western Alps). The compositional variability of successive growth zones is characterized using standardized X-ray maps and the program XMapTools. The model suggests that Permian garnet cores crystallized under granulite-facies conditions at T>800 °C and P = 6 kbar. During Alpine times, a first garnet rim grew at eclogite-facies conditions (650 °C, 16 kbar) at the expense of the garnet core. A second rim was added at lower P (∼11 kbar) and 630 °C. In total, garnet resorption is modeled to amount to ∼9 vol% during the Alpine evolution; this value is supported by our observations in X-ray compositional maps

A Smartphone-Based Tool for Rapid, Portable, and Automated Wide-Field Retinal Imaging.

Purpose:High-quality, wide-field retinal imaging is a valuable method for screening preventable, vision-threatening diseases of the retina. Smartphone-based retinal cameras hold promise for increasing access to retinal imaging, but variable image quality and restricted field of view can limit their utility. We developed and clinically tested a smartphone-based system that addresses these challenges with automation-assisted imaging. Methods:The system was designed to improve smartphone retinal imaging by combining automated fixation guidance, photomontage, and multicolored illumination with optimized optics, user-tested ergonomics, and touch-screen interface. System performance was evaluated from images of ophthalmic patients taken by nonophthalmic personnel. Two masked ophthalmologists evaluated images for abnormalities and disease severity. Results:The system automatically generated 100° retinal photomontages from five overlapping images in under 1 minute at full resolution (52.3 pixels per retinal degree) fully on-phone, revealing numerous retinal abnormalities. Feasibility of the system for diabetic retinopathy (DR) screening using the retinal photomontages was performed in 71 diabetics by masked graders. DR grade matched perfectly with dilated clinical examination in 55.1% of eyes and within 1 severity level for 85.2% of eyes. For referral-warranted DR, average sensitivity was 93.3% and specificity 56.8%. Conclusions:Automation-assisted imaging produced high-quality, wide-field retinal images that demonstrate the potential of smartphone-based retinal cameras to be used for retinal disease screening. Translational Relevance:Enhancement of smartphone-based retinal imaging through automation and software intelligence holds great promise for increasing the accessibility of retinal screening

Adjusted Tornado Probabilities

Tornado occurrence rates computed from the available reports are biased low relative to the unknown true rates. To correct for this low bias, the authors demonstrate a method to estimate the annual probability of being struck by a tornado that uses the average report density estimated as a function of distance from nearest city/town center. The method is demonstrated on Kansas and then applied to 15 other tornado-prone states from Nebraska to Tennessee. States are ranked according to their adjusted tornado rate and comparisons are made with raw rates published elsewhere. The adjusted rates, expressed as return periods, arestates, including Alabama, Mississippi, Arkansas, and Oklahoma. The expected annual number of people exposed to tornadoes is highest for Illinois followed by Alabama and Indiana. For the four states with the highest tornado rates, exposure increases since 1980 are largest for Oklahoma (24%) and Alabama (23%)

The Incentive Effects of Higher Education Subsidies on Student Effort

This paper uses a game-theoretic model to analyze the disincentive effects of low-tuition policies on student effort. The model of parent and student responses to tuition subsidies is then calibrated using information from the National Longitudinal Survey of Youth 1979 and the High School and Beyond Sophomore Cohort: 1980-92. I find that although subsidizing tuition increases enrollment rates, it reduces student effort. This follows from the fact that a high-subsidy, low-tuition policy causes an increase in the percentage of less able and less highly motivated college graduates. Additionall

Golden Years? The Labor Market Effects of Caring for Grandchildren

The number of Americans raising grandchildren has been rising steadily. In this paper, we add to what is known about the implications of this trend by focusing on the economic effects of raising a grandchild. We make use of a unique data set compiled from the Panel Study of Income Dynamics along with its Parent Identification File. Using this nationally representative sample of 3,240 grandparents who are heads of households, we estimate the effect of taking in a grandchild on a grandparent's labor force participation and hours worked. We estimate ordinary and two-stage models that distinguishing between grandparents living only with grandchildren (skipped generation families) and those who also have taken in their own children (three-generation families). The results suggest that caring for grandchildren leads to greater attachment to the labor force, especially in skipped-generation families, for grandfathers, and among married grandparent

Nonrenewable Resources, Strategic Behavior and the Hotelling Rule: An Experiment

This study uses the methods of experimental economics to investigate possible causes for the failure of the Hotelling rule for nonrenewable resources. We argue that as long as resource stocks are large enough, producers may choose to (partially) ignore the dynamic component of their production decision, shifting production to the present and focusing more on strategic behavior. We experimentally vary stock size in a nonrenewable resource duopoly setting and find that producers with large stocks indeed pay significantly less attention to variables related to dynamic optimization,leading to a failure of the Hotelling rule

Empirical Analysis of the Assessment of Innovation Effects in U.S. Merger Cases

In this empirical study all mergers that have been challenged by the U.S. antitrust agencies FTC and DOJ between 1995 and 2008 were analyzed in regard to the question to what extent and how the agencies assessed the innovation effects of mergers. Theoretical background is the still open question how negative effects of mergers on innovation should be taken into account in merger policy. Although we can show in our study that in one third of all challenged mergers also innovation concerns were raised, the results also point to a still existing large degree of uneasiness and inconsistencies of the agencies in regard to the assessment of innovation effects. A particularly interesting result is that - despite the wide-spread rejection of the "innovation market approach" in the antitrust debate - the agencies used more an innovationspecific assessment approach that includes also innovation in the market definition than the pure traditional product market concept. Additionally, we also found significant differences between the assessment approaches of the FTC and the DOJ