Full-length prepro-alpha-factor can be translocated across the mammalian microsomal membrane only if translation has not terminated.

We have previously shown that fully synthesized prepro-alpha-factor (pp alpha F), the precursor for the yeast pheromone alpha-factor, can be translocated posttranslationally across yeast rough microsomal (RM) membranes from a soluble, ribosome-free pool. We show here that this is not the case for translocation of pp alpha F across mammalian RM. Rather we found that a small amount of translocation of full-length pp alpha F is observed, but is solely due to polypeptide chains that were still ribosome bound and covalently attached to tRNA, i.e., not terminated. In addition, both signal recognition particle (SRP) and SRP receptor are required, i.e., the same targeting machinery that is normally responsible for the coupling between protein synthesis and translocation. Thus, the molecular requirements for targeting are distinct from posttranslational translocation across yeast RM. As termination is generally regarded as part of translation, the translocation of full-length pp alpha F across mammalian RM does not occur "posttranslationally," albeit independent of elongation. Most other proteins for which posttranslational translocation across mammalian RM was previously claimed fall into the same category in that ribosome attachment as peptidyl-tRNA is required. To clearly separate these two distinct processes, we suggest that the term posttranslational be reserved for those processes that occur in the complete absence of the translational machinery. We propose the term "ribosome-coupled translocation" for the events described here

Light Collimation and Focussing by a Thin Flat Metallic Slab

We present experimental and theoretical work showing that a flat metallic slab can collimate and focus light impinging on the slab from a punctual source. The effect is optimised when the radiation is around the bulk, not at the surface, plasma frequency. And the smaller the imaginary part of the permittivity is, the better the collimation. Experiments for Ag in the visible as well as calculations are presented. We also discuss the interesting case of the Aluminium whose imaginary part of the permittivity is very small at the plasma frequency in UV radiation. Generalization to other materials and radiations are also discussed.Comment: 6 pages, 3 figures. To be published on Optics Lette

Convergent sequences of perturbative approximations for the anharmonic oscillator II. Compact time approach

We present an alternative pathway in the application of the variation improvement of ordinary perturbation theory exposed in [1] which can preserve the internal symmetries of a model by means of a time compactification.Comment: 21 pages, 4 Postscript figures available through anonymous ftp at ftp://algol.lpm.univ-montp2.fr ; replaces version which could not be postscripted presumably for lack of figures.uu fil

Do Transaction Costs and Risk Preferences Influence Marketing Arrangements in the Illinois Hog Industry?

Risk reduction and transaction costs are often used to explain contracting in the U.S. hog industry with little empirical support. Using a unified conceptual framework that draws from risk behavior and transaction cost theories, in combination with unique survey and accounting data, we demonstrate that risk preferences and asset specificity impact Illinois producers’ use of contracts and spot markets. In particular, producers’ investments in specific hog genetics and human capital are related to selection of long-term marketing contracts over spot markets. Producers who perceive greater levels of price risk and/or are more averse are more (less) likely to use contracts (spot markets). Key words: asset specificity, contracts, hogs, risk attitude, risk behavior, risk perception, transaction costs economic

Brazil in the 21st century: How to escape the high real interest trap?

The hope that lower real interest rates and higher growth would follow the floatation of the currency was in large measure frustrated. Two international liquidity crises, caused by the reversal of capital flows, hit in 2001 and 2002. These crises were associated with higher interest rates, lower economic activity and higher inflation. Therefore, the name exchange-rate stagflation seems to characterize the essence of the phenomenon. A stylized model, due to Caballero and Krishnamurthy [2002], was used to explain the events. The main characteristic of the model is that domestic investment depends on the aggregate international liquidity of the economy, which is a limiting factor. During a liquidity crisis, the amount of liquidity is reduced, and the economy falls in recession. Neither the fiscal authority nor the monetary authority can reflate the economy by increasing government expenditures or the money supply. The bulk of the difficulties Brazil is currently facing derives from the uncertainty associated with the course of the future economic policy to be followed by the new administration, and to the sustainability of the public debt. To avert a painful default, real interest rates must fall and sustained growth must resume. To increase the chances of success, several policy measures are suggested: · To increase the exportability of the economy; · To increase the fiscal effort, in order to help dispel the doubts over the sustainability of the public debt; · To increase the credibility of the monetary authority, by conferring instrument independence to the Brazilian Central Bank; and · To resume the debt management efforts to lengthen the debt profile while reducing the indexation to the exchange rate and to the Selic short term rate, by making larger user of inflation-linked bonds. When and if the current international liquidity crisis is overcome, the above measures will help Brazil to lower the real interest rates and achieve sustained growth.

Who is coming from Vanuatu to New Zealand under the new Recognised Seasonal Employer (RSE) program?

New Zealand’s new Recognised Seasonal Employer (RSE) program allows workers from the Pacific Islands to come to New Zealand for up to seven months to work in the horticulture and viticulture industries. One of the explicit objectives of the program is to encourage economic development in the Pacific. In this paper we report on the results of a baseline survey taken in Vanuatu, which allows us to examine who wants to participate in the program, and who is selected amongst those interested. We find the main participants are males in their late 20s to early 40s, most of whom are married and have children. Most workers are subsistence farmers in Vanuatu and have not completed more than 10 years of schooling. Such workers would be unlikely to be accepted under existing migration channels. Nevertheless, we find RSE workers from Vanuatu to come from wealthier households, and have better English literacy and health than individuals not applying for the program. Lack of knowledge about the policy and the costs of applying appear to be the main barriers preventing poorer individuals applying