Fertilized Lytechinus eggs exposed to the volatile anaesthetic halothane before metaphase do not undergo cytoplasmic cleavage. This effect has been correlated with the failure of the contractile ring ...to assemble. Comparative studies on mitotic apparatuses isolated from control and halothane-treated cells show that halothane significantly impairs both spindle and aster growth as early as metaphase. When transferred to control solutions, halothane-treated cells initiate furrowing activity in association with either the first or second mitotic division, depending on the duration of the exposure to anaesthetic and the concentration employed. In contrast to these effects, halothane has no effect on any aspect of the cleavage process if applied later than metaphase. In this case, furrows develop even in the presence of halothane, deepen progressively, and complete cell division. These observations confirm and extend previous studies on echinoderm eggs exposed to volatile anaesthetics, and support the view that anaesthetic agents indirectly prevent cell cleavage by inhibiting the growth of mitotic apparatus.
The objective of this paper is to understand how loan structure affects (i) the borrower’s selection of a mortgage contract and (ii) the aggregate economy. We develop a quantitative equilibrium ...theory of mortgage choice where households can choose from a menu of long-term (nominal) mortgage loans. The model accounts for observed patterns in housing consumption, ownership, and portfolio allocations. We find that the loan structure is a quantitatively significant factor in a household’s housing finance decision. The model suggests that the mortgage structure preferred by a household is dependent on age and income and that loan products with low initial payments offer an alternative to mortgages with no downpayment. These effects are more important when inflation is low. The presence of inflation reduces the real value of the mortgage payment and the outstanding loan overtime reducing mobility. Changes in the structure of mortgages have implications for risk sharing.
Light and spectroscopy are among the most important and frequently taught topics in introductory college-level general education astronomy courses (hereafter Astro 101). This is due to the fact that ...the vast majority of observational data studied by astronomers arrives at Earth in the form of light. While there are many processes by which matter can emit and absorb light, Astro 101 courses typically limit their instruction to the Bohr model of the atom and electron energy level transitions. In this paper, we report on the development of a new Lecture-Tutorial to help students learn about other processes that are responsible for the emission and absorption of light, namely molecular rotations, molecular vibrations, and the acceleration of charged particles by magnetic fields. Note that this paper primarily focuses on describing the variety of representations and reasoning tasks designed for this Lecture-Tutorial; while the end of this paper highlights some data that are suggestive of the Lecture-Tutorial's effectiveness, our more comprehensive analysis of its efficacy will be presented in a future publication.
This paper analyzes the connection between the asymmetric tax treatment of homeowners and landlords and the progressivity of income taxation using a quantitative overlapping generations general ...equilibrium model with housing and rental markets. Our model emphasizes the determinants of tenure choice (owning versus renting) and the household decision to supply housing services to the rental market. This formulation breaks the link between the rental price and the equilibrium interest rate. Hence, the aggregate supply of rental property responds differently to the direction of rental price changes, marginal tax rate changes, and maintenance cost changes. We show that the model replicates the key factors and the distributional patterns of ownership, house size, and landlords. The degree of progressivity in the income tax code has important implications for housing tenure and housing consumption. We find that a movement toward a less progressive income tax code can generate sizable increases in homeownership and welfare that result from the equilibrium effects and a portfolio reallocation mechanism absent in economies with single assets (e.g., Conesa and Krueger 2006). We find that the removal of existing asymmetries in the tax code has effects on housing that differ from those reported in the literature. We show that housing policy can increase the ownership rate of a particular segment of the population but generate nontrivial distributional costs. The welfare increases are no larger than those found when the progressivity of the tax code is reduced.
In this paper, we study the decision to purchase life insurance as part of a lifecycle plan of consumption, savings, and labor supply. Households are subject to idiosyncratic risk in their labor ...productivity as well as the composition and size of their family, and respond by accumulating savings, working, and purchasing life insurance to hedeg against death of an adult. Using a calibrated general equilibrium model that matches key facts from the income and wealth distribution, we estimate that consumption-smoothing motives produce excessive LI holdings relative to the data, even when load factors consistent with estimates are introduced
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