Brownian motion.

Thesis (M.A.)--Boston Universit

NTF: Soldering Technology Development for Cryogenics

The advent of the National Transonic Facility (NTF) brought about a new application for an old joining method, soldering. Soldering for use at cryogenic temperatures requires that solders remain ductile and free from tin-pest (grey tin), have toughness to withstand aerodynamic loads associated with flight research, and maintain their surface finishes. Solders are used to attach 347 Stainless-Steel tubing in surface grooves of models. The solder must fill up the gap and metallurgically bound to the tubing and model. Cryogenic temperatures require that only specific materials for models can be used, including: Vasco Max 200 CVM, lescalloy A-286 Vac Arc, pH 13-8 Mo. Solders identified for testing at this time are: 50% Sn - 49.5% Pb - 0.5% Sb, 95% Sn - 5% Sb, 50% In 50% Pb, and 37.5% Sn - 37.5% Pb - 25% In. With these materials and solders, it is necessary to determine their solderability. After solderability is determined, tube/groove specimens are fabricated and stressed under cryogenic temperatures. Compatible solders are then used for acutual models

By How Much Does GDP Rise If the Government Buys More Output?

macroeconomics, GDP, U.S. Government, output, multipliers

The Process of Inflation in the Labor Market

macroeconomics, inflation, labor market

Investment Under Uncertainty: Theory and Tests with Industry Data

Under the assumption of constant returns to scale, there is a very simple, easily testable condition for optimal investment under uncertainty. Application of the test requires no parametric assumptions about technology and no assumptions about the competitiveness of the output market. The condition is that the expected marginal revenue product of labor equal the expected rental price of capital. The condition implies a certain invariance property for a modified version of Solow's productivity residual. Tests of the invariance property for U.S. industry data give very strong rejection in quite a few industries. The interpretation of rejection is either that the technology has increasing returns (possibly because of fixed costs) or that fins systematically over-invest.

Fluctuation in Equilibrium Unemployment

Fluctuations in the equilibrium rate of unemployment can only be understood within a theory of the natural or equilibrium rate. It is not enough to say that unemployment is the difference between supply and demand in the labor market, though of course it always will be. In equilibrium, no participants in the market can have an unexploited opportunity to make themselves better off. At the equilibrium unemployment rate, employers cannot obtain labor at lower cost by offering work at below the market wage to the unemployed. Unemployed workers cannot raise their effective real incomes by taking lower wages in exchange for immediate employment. The task of the theory is to explain why any unemployment remains at all when these conditions are satisfied. Part of this problem has been studied in detail in the "search theory" of unemployment -- once a worker becomes unemployed, it is reasonably well understood why the worker does not become employed again immediately. The theory of why people become unemployed in the first place is less well developed and is the main concern of this paper. Most of the unemployed are looking for new work because their previous jobs ran out. Consequently, the main ingredient of a theory of the flow of workers into unemployment is a theory of the duration of employment. Such a theory is developed here, along reasonably standard lines.

The Relation Between Price and Marginal Cost in U.S. Industry

An examination of data on labor input and the quantity of output reveals that most U.S. industries have marginal costs far below their prices. The corilusion rests on the empirical finding that cyclical variations in labor input are small compared to variations in output. In booms, firms produce substantially more output and sell it for a price that exceeds the costs of the added inputs. The paper documents the disparity between price and marginal cost,where marginal cost is estimated from variations in cost from one year to the next. It considers a wide variety of explanations of the flndings that are consistent with competition, but none is found to be plausible.

Aggregate Job Destruction and Inventory Liquidation

In a recession, jobs are destroyed and inventories are liquidated. I concentrate on the intertemporal mechanisms that result in economy-wide job destruction and inventory runoffs. Forces that raise the real interest rate -- especially temporarily -- also cause destruction and runoffs. I consider a model where the job destruction decision is made efficiently, will full consideration of the search costs imposed on discharged workers. I also consider a model of inefficient job destruction, where employers discharge workers who are paid fixed wages as long as they are employed. The impulse response functions for these models resemble those found in data for the United States. A shock that causes a jump in the expected real interest rate results in an immediate spike of job destruction and inventory liquidation, followed by a declining pattern of additional destruction and runoff.

Corporate Earnings Track the Competitive Benchmark

Earnings are the flow of value created by corporations. I concentrate on the concept called EBITDA earnings before interest, taxes, depreciation, and amortization. This measure captures the results of the substantive non-financial activities of corporations and corresponds to the rental price of capital multiplied by the quantity of capital. I measure earnings per dollar of capital for all U.S. corporations and in 5 selected industries. I develop a competitive benchmark for the level of earnings, which takes account of adjustment costs, taxes, depreciation, and the financial opportunity cost of funds. I find that aggregate corporate earnings track the benchmark reasonably closely, leaving a relatively small unexplained component. Thus evidence of the flow of value gives little help in explaining the large discrepancies found in earlier work in the level of the market value of claims on corporations relative to the replacement cost of the capital stock. At the industry level, I find more volatility of both actual and benchmark earnings, with a high correlation between the two in 3 of the 5 industries.

In Honor of William Brainard and George Perry

macroeconomics, George Perry, William Brainard, BPEA, Brookings Papers on Economic Activity, Brookings Panel on Economic Activity