Confronting quintessence models with recent high-redshift supernovae data

We confront the predictions of different quintessence models with recent measurements of the luminosity distance from two sets of supernovae type Ia. In particular, we consider the 157 SNe Ia in the Gold dataset with z < 1.7, and the more recent data containing 71 supernovae obtained by the Supernova Legacy Survey (SNLS) with z < 1. We numerically solve the evolution equations for the Ratra-Peebles inverse power-law model, the double exponential and the hyperbolic cosine quintessence models. We obtain confidence regions from the two datasets in the Omega(M)-alpha and Omega(M)-w(phi) planes for the different models and compare their predictions with dark energy models with constant equation of state

3C a multi-wavelength database for the future GTC cosmological surveys

The 3C Database aims to provide complete multi-wavelength information over different cosmological fields, such as GOODS, Groth or Sa68 allowing detailed studies on wide samples of galaxies

Does the Time Inconsistency Problem Make Flexible Exchange Rates Look Worse than You Think?

Lack of commitment in monetary policy leads to the well known Barro-Gordon inflation bias. In this paper, we argue that two phenomena associated with the time inconsistency problem have been overlooked in the exchange rate debate. We show that, absent commitment, independent monetary policy can also induce expectation traps - that is, welfare-ranked multiple equilibria - and perverse policy responses to real shocks - that is, an equilibrium policy response that is welfare inferior to policy inaction. Both possibilities imply higher macroeconomic volatility under flexible exchange rates than under fixed exchange rates

Constraints on Quintessence From Using Cosmological Data

Recent data, including the three--year WMAP data, the full 2dF galaxy power spectrum and the first--year data of the Supernova Legacy Survey, are used to constrain model parameters in quintessence cosmologies. In particular, we discuss the inverse power--law (RP) and SUGRA potentials and compare parameter constraints with those for LCDM. Both potentials fit current observations with a goodness of fit comparable or better than LCDM. The constraints on the energy scale Lambda_DE appearing in both potential expressions are however different. For RP, only energy scales around the cosmological constant limit are allowed, making the allowed models quite similar to LCDM. For SUGRA, Lambda_DE values approximately up to Electroweak energy scale are still allowed, while other parameter intervals are slightly but significantly displaced. In particular a value of the primeval spectral index n_s = 1 is still allowed at the 95% c.l., and this can have an impact on constraints on possible inflationary potentials.Comment: 12 pages, 4 figures, submitted to JCA

Identification and characterization of a novel non-structural protein of bluetongue virus

Bluetongue virus (BTV) is the causative agent of a major disease of livestock (bluetongue). For over two decades, it has been widely accepted that the 10 segments of the dsRNA genome of BTV encode for 7 structural and 3 non-structural proteins. The non-structural proteins (NS1, NS2, NS3/NS3a) play different key roles during the viral replication cycle. In this study we show that BTV expresses a fourth non-structural protein (that we designated NS4) encoded by an open reading frame in segment 9 overlapping the open reading frame encoding VP6. NS4 is 77–79 amino acid residues in length and highly conserved among several BTV serotypes/strains. NS4 was expressed early post-infection and localized in the nucleoli of BTV infected cells. By reverse genetics, we showed that NS4 is dispensable for BTV replication in vitro, both in mammalian and insect cells, and does not affect viral virulence in murine models of bluetongue infection. Interestingly, NS4 conferred a replication advantage to BTV-8, but not to BTV-1, in cells in an interferon (IFN)-induced antiviral state. However, the BTV-1 NS4 conferred a replication advantage both to a BTV-8 reassortant containing the entire segment 9 of BTV-1 and to a BTV-8 mutant with the NS4 identical to the homologous BTV-1 protein. Collectively, this study suggests that NS4 plays an important role in virus-host interaction and is one of the mechanisms played, at least by BTV-8, to counteract the antiviral response of the host. In addition, the distinct nucleolar localization of NS4, being expressed by a virus that replicates exclusively in the cytoplasm, offers new avenues to investigate the multiple roles played by the nucleolus in the biology of the cell

Global Governance Behind Closed Doors : The IMF Boardroom, the Enhanced Structural Adjustment Facility, and the Intersection of Material Power and Norm Change in Global Politics

Up on the 12th floor of its 19th Street Headquarters, the IMF Board sits in active session for an average of 7 hours per week. Although key matters of policy are decided on in the venue, the rules governing Boardroom interactions remain opaque, resting on an uneasy combination of consensual decision-making and weighted voting. Through a detailed analysis of IMF Board discussions surrounding the Enhanced Structural Adjustment Facility (ESAF), this article sheds light on the mechanics of power in this often overlooked venue of global economic governance. By exploring the key issues of default liability and loan conditionality, I demonstrate that whilst the Boardroom is a more active site of contestation than has hitherto been recognized, material power is a prime determinant of both Executive Directors’ preferences and outcomes reached from discussions. And as the decisions reached form the backbone of the ‘instruction sheet’ used by Fund staff to guide their everyday operational decisions, these outcomes—and the processes through which they were reached—were factors of primary importance in stabilizing the operational norms at the heart of a controversial phase in the contemporary history of IMF concessional lending

Will the Recovery Continue? Four Fragile Markets, Four Years Later

In this brief, Research Scholar Greg Hannsgen and President Dimitri B. Papadimitriou focus on the risks and possibilities ahead for the US economy. Using a Keynesian approach and drawing from the commentary of other observers, they analyze publicly available data in order to assess the strength and durability of the expansion that probably began in 2009. They focus on four broad groups of markets that have shown signs of stress for the last several years: financial markets, markets for household goods and services, commodity markets, and labor markets. This kind of analysis does not yield numerical forecasts but it can provide important clues about the short-term outlook for the country's economic well-being, and cast light on some longer-run threats. In particular, dangers and stresses in the financial and banking systems are presently very serious, and labor market data show every sign of a widespread and severe weakness in aggregate demand. Unless there is new resolve for effective government action on the jobs front, drastic cuts in much-needed federal, state, and local programs will become the order of the day in the United States, as in much of Europe

The Output Gap, the Labor Wedge, and the Dynamic Behavior of Hours

We use a standard quantitative business cycle model with nominal price and wage rigidities to estimate two measures of economic ineffciency in recent U.S. data: the output gap - the gap between the actual and effcient levels of output - and the labor wedge - the wedge between households' marginal rate of substitution and firms' marginal product of labor. We establish three results. (i ) The output gap and the labor wedge are closely related, suggesting that most ineffciencies in output are due to the ineffcient allocation of labor. (ii ) The estimates are sensitive to the structural interpretation of shocks to the labor market, which is ambiguous in the model. (iii ) Movements in hours worked are essentially exogenous, directly driven by labor market shocks, whereas wage rigidities generate a markup of the real wage over the marginal rate of substitution that is acyclical. We conclude that the model fails in two important respects: it does not give clear guidance concerning the effciency of business cycle uctuations, and it provides an unsatisfactory explanation of labor market and business cycle dynamics