Dry Dilution Refrigerator with He-4 Precool Loop

He-3/He-4 dilution refrigerators (DR) are very common in sub-Kelvin temperature research. We describe a pulse tube precooled DR where a separate He-4 circuit condenses the He-3 of the dilution loop. Whereas in our previous work the dilution circuit and the He-4 circuit were separate, we show how the two circuits can be combined. Originally, the He-4 loop with a base temperature of ~ 1 K was installed to make an additional cooling power of up to 100 mW available to cool cold amplifiers and electrical lines. In the new design, the dilution circuit is run through a heat exchanger in the vessel of the He-4 circuit so that the condensation of the He-3 stream of the DR is done by the He-4 stage. A much reduced condensation time (factor of 2) of the He-3/He-4 gas mixture at the beginning of an experiment is achieved. A compressor is no longer needed with the DR as the condensation pressure remains below atmospheric pressure at all times; thus the risk of losing expensive He-3 gas is small. The performance of the DR has been improved compared to previous work: The base temperature of the mixing chamber at a small He-3 flow rate is now 4.1 mK; at the highest He-3 flow rate of 1.2 mmol/s this temperature increases to 13 mK. Mixing chamber temperatures were measured with a cerium magnesium nitrate (CMN) thermometer which was calibrated with a superconducting fixed point device.Comment: Cryogenic Engineering Conference 201

Long Term Debt and the Political Support for a Monetary Union

This paper examines the role of long term debt for the political support of a monetary union or, more generally, an inflation-reduction policy. The central idea is that the decision about membership in the union leads to a redistribution between debtors and creditors, if they are holding long term debt with a nominally fixed interest rate, as well as tax payers. For example, if joining the union means a decrease in the inflation rate, creditors should favor joining while debtors should be against it. A government of a high inflation country might strategically try to exploit this effect by selling more long term debt denominated in its own currency at a fixed nominal rate rather than a foreign currency such as the Dollar (or, almost equivalently, as floating-rate debt or rolled-over short-term debt) to its citizens. We show that the effect on political support is unclear. While the "creditor effect" of increasing the number of agents holding domestically denominated debt helps generating support for joining the union, the "tax effect" of having to raise more taxes in order to pay for the increased real debt payments after a successful monetary union works in the opposite way. The paper then studies a number of special cases and ramifications. The case of Italy is examined more closely. The paper argues that recent debt management policy in Italy is probable to have eroded the political support for actions aimed at enhancing EMU membership chancesmonetary integration;national debt;monetary policy;inflation

Did the FED Surprise the Markets in 2001? A Case Study for Vars with Sign Restrictions

In 2001, the Fed has lowered interest rates in a series of cuts, starting from 6.5 % at the end of 2000 to 2.0 % by early November.This paper asks, whether the Federal Reserve Bank has been surprising the markets, taking as given the conventional view about the effect of monetary policy shocks.New econometric techniques turn out to be particularly suitable for answering this question: this paper can be viewed as a showcase and case study for their application.In order to concentrate on the Greenspan period, a vector autoregression is fitted to US data, starting in 1986 and ending in September 2001.Monetary policy shocks are identified, using the new sign restriction methodology of Uhlig (1999), imposing the "conventional view" that contractionary policy shocks lead to a rise in interest rates and declines in nonborrowed reserves, prices and output.We find that neither the Fed policy choices in 2001 nor those of 2000 were surprising.We provide a method to "explain" these interest rate movements by decomposing them into their sources. Finally, we argue that constant-interest-rate projections like those popular at many central banks are of limited informational value, can be highly misleading, and should instead be replaced by on-the-equilibrium-path projections.monetary policy;vector autoregressive models

Transition and Financial Collapse

One of the many problems facing the countries in transition from socialism to capitalism after the initial phase of privatization and restructuring is the lack of proven entrepreneurial talent in addition to a low initial level of capital. New entrepreneurs might find it hard to finance their start-up enterprises. This paper therefore argues that a financial collapse and thus a collapse of the new entrepreneurial sector might occur. First, the lack of financial intermediation in transition economies is examined empirically before proceeding to a theoretical model. Using IMF data on claims to the private sector, we find that the extent of financial intermediation in these countries is comparable to developing rather than industrialized countries. The theoretical part analyzes an overlapping generations model with heterogenous entrepreneurial qualities and private information. A financial collapse can result, if young agents are too poor to provide enough collateral for financing a small project to prove their qualities as entrepreneur and no proven middle-aged entrepreneurs are available who can be entrusted with enough funds to run big projects. In that case, the economy contracts to an agricultural steady state. Possible remedies are discussed. In particular, large inequality or a large-scale, long-lasting government program of subsidizing investment help to overcome the danger of a financial collapse.

What are the Effects of Monetary Policy on Output? Results from an Agnostic Identification Procedure

This paper proposes to estimate the effects of monetary policy shocks by a new \agnostic" method, imposing sign restrictions on the impulse responses of prices, nonborrowed reserves and the federal funds rate in response to a monetary policy shock. No restrictions are imposed on the response of real GDP to answer the key question in the title. We find that "contractionary" monetary policy shocks have an ambiguous effect on real GDP. Otherwise, the results found in the empirical VAR literature so far are largely confirmed. The results could be paraphrased as a new Keynesian-new classical synthesis: even though the general price level is sticky for a period of about a year, money may well be close to neutral. We provide a counterfactual analysis of the early 80's, setting the monetary policy shocks to zero after December 1979, and recalculating the data. We found that the differences between observed real GDP and counterfactually calculated real GDP was not very large. Thus, the label "Volcker-recession" for the two recessions in the early 80's appears to be misplaced.vector autoregression;monetary policy shocks;identification;monetary neutrality

Explaining Asset Prices with External Habits and Wage Rigidities in a DSGE Model.

In this paper, I investigate the scope of a model with exogenous habit formation - or `catching up with the Joneses`, see Abel (1990) - to generate the observed equity premium as well as other key macroeconomic facts. Along the way, I derive restrictions for four out of eight parameters for a rather general preference specification of habit formation by imposing consistency with long-run growth, the leisure share, the aggregate Frisch elasticity of labor supply, the observed risk-free rate, and the observed Sharpe ratio. I show that a DSGE model with (exogenous and lagged) habits in both leisure and consumption, but not necessarily with additional persistence, is well capable of matching the observed asset market facts as well as macro facts, provided one allows for moderate real wage stickiness and provided one allows for sufficient curvature on preferences, as dictated by the asset market observations. Without wage stickiness, delivery on both the asset pricing implications as well as the macroeconomic implications seems to be much harder.asset pricing, wage rigidity, habit formation, Frisch elasticity, Sharpe ratio, log-linear approximation