208 research outputs found

    Permanent and transitory policy shocks in an empirical macro model with asymmetric information

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    Despite a large literature documenting that the efficacy of monetary policy depends on how inflation expectations are anchored, many monetary policy models assume: (1) the inflation target of monetary policy is constant; and, (2) the inflation target is known by all economic agents. This paper proposes an empirical specification with two policy shocks: permanent changes to the inflation target and transitory perturbations of the short-term real rate. The public sector cannot correctly distinguish between these two shocks and, under incomplete learning, private perceptions of the inflation target will not equal the true target. The paper shows how imperfect policy credibility can affect economic responses to structural shocks, including transition to a new inflation target - a question that cannot be addressed by many commonly used empirical and theoretical models. In contrast to models where all monetary policy actions are transient, the proposed specification implies that sizable movements in historical bond yields and inflation are attributable to perceptions of permanent shocks in target inflation

    Term structure transmission of monetary policy

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    The sensitivity of bond rates to macro variables appears to vary both over time and over forecast horizons. The latter may be due to differences in forward rate term premiums and in bond trader perceptions of anticipated policy responses at different forecast horizons. Determinacy of policy transmission through bond rates requires a lower bound on the average responsiveness of term premiums and anticipated policy responses to inflation.Monetary policy

    Minding the gap : central bank estimates of the unemployment natural rate

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    A time-varying parameter framework is suggested for use with real-time multiperiod forecast data to estimate implied forecast equations. The framework is applied to historical briefing forecasts prepared for the Federal Open Market Committee to estimate the U.S. central bank’s ex ante perceptions of the natural rate of unemployment. Relative to retrospective estimates, empirical results do not indicate severe underestimation of the natural rate of unemployment in the 1970s.Unemployment

    The role of expectations in the FRB/US macroeconomic model

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    In the past year, the staff of the Board of Governors of the Federal Reserve System began using a new macroeconomic model of the U.S. economy referred to as the FRB/US model. This system of mathematical equations, describing interactions among economic measures such as inflation, interest rates, and gross domestic product, is one of the tools used in economic forecasting and the analysis of macroeconomic policy issues at the Board. The FRB/US model replaces the MPS model, which, with periodic revisions, had been used at the Federal Reserve Board since the early 1970s. A key feature of the new model is that expectations of future economic conditions are explicit in many of its equations. Because of this clear delineation of expectations, the FRB/US model can be used to study issues that would be difficult or impossible to study with the MPS model. For example, the new model can show how the economy's response to specific events, such as a reduction in defense spending, may vary considerably with the speed at which the public recognizes that the event has occurred or will occur.Econometric models ; Federal Reserve System ; Forecasting

    Chytrid fungus infections in laboratory and introduced <i>Xenopus laevis </i>populations:assessing the risks for U.K. native amphibians

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    The chytrid fungus Batrachochytrium dendrobatidis (Bd) is notorious amongst current conservation biology challenges, responsible for mass mortality and extinction of amphibian species. World trade in amphibians is implicated in global dissemination. Exports of South African Xenopus laevis have led to establishment of this invasive species on four continents. Bd naturally infects this host in Africa and now occurs in several introduced populations. However, no previous studies have investigated transfer of infection into co-occurring native amphibian faunas. A survey of 27 U.K. institutions maintaining X. laevis for research showed that most laboratories have low-level infection, a risk for native species if animals are released into the wild. RT-PCR assays showed Bd in two introduced U.K. populations of X. laevis, in Wales and Lincolnshire. Laboratory and field studies demonstrated that infection levels increase with stress, especially low temperature. In the U.K., native amphibians may be exposed to intense transmission in spring when they enter ponds to spawn alongside X. laevis that have cold-elevated Bd infections. Exposure to cross-infection has probably been recurrent since the introduction of X. laevis, &gt;20years in Lincolnshire and 50years in Wales. These sites provide an important test for assessing the impact of X. laevis on Bd spread. However, RT-PCR assays on 174 native amphibians (Bufo, Rana, Lissotriton and Triturus spp.), sympatric with the Bd-infected introduced populations, showed no foci of self-sustaining Bd transmission associated with X. laevis. The abundance of these native amphibians suggested no significant negative population-level effect after the decades of co-occurrence

    Impact of Acute Dietary Manipulations on Dual-Energy X-ray Absorptiometry Estimates of Visceral Adipose Tissue

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    Dual-energy x-ray absorptiometry (DXA) is viewed as a superior method of body composition assessment, but whole-body DXA scans are impacted by variation in pre-assessment activities, such as eating and drinking. DXA software now allows for estimation of visceral adipose tissue (VAT), which has been implicated in a number of diseases. It is unknown to what extent food and fluid intake affect VAT estimates. PURPOSE: determine the effects of acute high-carbohydrate (HC) and very low-carbohydrate (VLC) diets on DXA estimates of VAT. METHODS: Male and female adults completed two one-day dietary conditions in random order: a VLC diet (1 – 1.5 g CHO/kg) and a HC diet (9 g CHO/kg). The diets were isocaloric to each other, and all food items were provided to participants. DXA scans were conducted in the morning after an overnight fast and in the afternoon soon after the third standardized meal. VAT volume, mass, and area were obtained, and paired samples t-tests were performed to compare the changes in VAT measures between diets. RESULTS: Fifteen males (age 22 ± 3, BF% 21 ± 5%) and eighteen females (age 21 ± 2, BF% 31 ± 5%) were included in the analysis. The change in VAT volume between the fasted and fed visits was different between diets (HC: +1.6%; VLC: -9.2%, p= 0.047). There were also trends for differences in VAT mass (p= 0.089) and area (p= 0.096) changes between diets. CONCLUSIONS: Within a single day, VAT estimates are differentially affected by isocaloric HC and VLC diets, with VLC consumption leading to reductions in VAT estimates. The content of the diet on the day of a DXA scan can affect estimates of VAT, which could spuriously influence the categorization of an individual’s health risk by DXA VAT estimates. Standardization of food intake prior to scans, preferably in the form of an overnight fast, should be employed to eliminate this important source of error

    Valuing All Languages in Europe

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    The VALEUR project (2004-2007) took as its focus the 'additional' languages of Europe. These are defined as all languages in use in contexts where they are not 'national', 'official', or 'dominant' languages. They include 'migrant' languages, 'regional/minority' languages, sign languages and 'non-territorial' languages of diasporas such as Yiddish and Romani. The project team brought together a range of expertise in sociolinguistics and language pedagogy, planning and research from Finland, Netherlands, Poland, Spain and the UK. We took as our starting point Council of Europe policies on plurilingualism and the desirability of promoting linguistic diversity both for individual citizenship and for social cohesion in Europe. Our aim was to map provision for additional languages in Europe, in a more systematic and inclusive way than ever before. We looked at provision at school level for different languages in different contexts in order to identify good practices to be shared. In order to achieve our objectives we drew on the good will and enthusiasm of workshop participants, who provided a wealth of information and insights from 21 of the Council of Europe member states. Our work is not definitive: its purpose is awareness-raising and to stimulate further activity to support the learning of all Europe's languages

    Supernovae in Early-Type Galaxies: Directly Connecting Age and Metallicity with Type Ia Luminosity

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    We have obtained optical spectra of 29 early-type (E/S0) galaxies that hosted type Ia supernovae (SNe Ia). We have measured absorption-line strengths and compared them to a grid of models to extract the relations between the supernova properties and the luminosity-weighted age/composition of the host galaxies. The same analysis was applied to a large number of early-type field galaxies selected from the SDSS spectroscopic survey. We find no difference in the age and abundance distributions between the field galaxies and the SN Ia host galaxies. We do find a strong correlation suggesting that SNe Ia in galaxies whose populations have a characteristic age greater than 5 Gyr are ~ 1 mag fainter at V(max) than those found in galaxies with younger populations. However, the data cannot discriminate between a smooth relation connecting age and supernova luminosity or two populations of SN Ia progenitors. We find that SN Ia distance residuals in the Hubble diagram are correlated with host-galaxy metal abundance, consistent with the predictions of Timmes, Brown & Truran (2003). The data show that high iron abundance galaxies host less-luminous supernovae. We thus conclude that the time since progenitor formation primarily determines the radioactive Ni production while progenitor metal abundance has a weaker influence on peak luminosity, but one not fully corrected by light-curve shape and color fitters. Assuming no selection effects in discovering SNe Ia in local early-type galaxies, we find a higher specific SN Ia rate in E/S0 galaxies with ages below 3 Gyr than in older hosts. The higher rate and brighter luminosities seen in the youngest E/S0 hosts may be a result of recent star formation and represents a tail of the "prompt" SN Ia progenitors.Comment: 44 pages, 11 figures, 4 tables; ApJ Accepted (Sept. 20, 2008 issue
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