1,366 research outputs found
Toward a Modern Macroeconomic Model Usable for Policy Analysis
This paper presents a macroeconomic model that is both a completely specified dynamic general equilibrium model and a probabilistic model for time series data. We view the model as a potential competitor to existing ISLM-based models that continue to be used for actual policy analysis. Our approach is also an alternative to recent efforts to calibrate real business cycle models. In contrast to these existing models, the one we present embodies all the following important characteristics: i) It generates a complete multivariate stochastic process model for the data it aims to explain, and the full specification is used in the maximum likelihood estimation of the model; ii) It integrates modeling of nominal variables -- money stock, price level, wage level, and nominal interest rate -- with modeling real variables; iii) It contains a Keynesian investment function, breaking the tight relationship of the return on investment with the capital-output ratio; iv) It treats both monetary and fiscal policy explicitly; v) It is based on dynamic optimizing behavior of the private agents in the model. Flexible-price and sticky-price versions of the model are estimated and their fits are evaluated relative to a naive model of no-change in the variables and to an unrestricted VAR. The paper displays the model's implications for the dynamic responses to structural shocks, including policy shocks, and evaluates the relative importance of various shocks for determining economic fluctuations.
High efficiency multifrequency feed
Antenna systems and particularly compact and simple antenna feeds which can transmit and receive simultaneously in at least three frequency bands, each with high efficiency and polarization diversity are described. The feed system is applicable for frequency bands having nominal frequency bands with the ratio 1:4:6. By way of example, satellite communications telemetry bands operate in frequency bands 0.8 - 1.0 GHz, 3.7 - 4.2 GHz and 5.9 - 6.4 GHz. In addition, the antenna system of the invention has monopulse capability for reception with circular or diverse polarization at frequency band 1
St. Louis in the Santa Fe Trade
Many works have been written concerning the Santa Fe trade and the various traders who had a part in carrying it on; but to the writer\u27s knowledge no one has written an account of the part which St. Louis had in this great commerce. Writers generally state the Santa Fe was the western end of the trail and Franklin of Independence was the eastern end. St. Louis was situated off the highway, as it were; and, although she might have participated in the trade, being off the highway, it is usually judged that her part in it was slight. The writer\u27s opinion is that St. Louis\u27 part in the Santa Fe trade was greater than has been generally believed
Dynamics of radiating braneworlds
If the observable universe is a braneworld of Randall-Sundrum type, then
particle interactions at high energies will produce 5-dimensional gravitons
that escape into the bulk. As a result, the Weyl energy density on the brane
does not behave like radiation in the early universe, but does so only later,
in the low energy regime. Recently a simple model was proposed to describe this
modification of the Randall-Sundrum cosmology. We investigate the dynamics of
this model, and find the exact solution of the field equations. We use a
dynamical systems approach to analyze global features of the phase space of
solutions.Comment: error in figures corrected, reference adde
The application of ecosystem thresholds in the management of tropical coral reefs: a review and synthesis
A review and synthesis was carried out on the extensive literature concerned with
ecosystem thresholds on tropical coral reefs to collate research carried out globally,
and highlight gaps in the existing knowledge. This study aims to inform the future
management of ecosystem thresholds of tropical coral reefs. Information was
gathered from existing literature concerning ecosystem thresholds at named tropical
coral reef locations and the distribution of studies was mapped in order to draw
conclusions about the state of threshold research on coral reefs, and to make
recommendations for future research and management. The synthesis highlighted
the negative influence of removing herbivorous grazers, and the need for quantitative
measures for the resilience of reefs to anthropogenic stress. It was also found that
previous research sites predominantly focused on two main areas; The Great Barrier
Reefs, and Caribbean reefs
Biosynthesis of the antifungal haterumalide, oocydin A, in Serratia, and its regulation by quorum sensing, RpoS and Hfq.
Polyketides represent an important class of bioactive natural products with a broad range of biological activities. We identified recently a large trans-acyltransferase (AT) polyketide synthase gene cluster responsible for the biosynthesis of the antifungal, anti-oomycete and antitumor haterumalide, oocydin A (ooc). Using genome sequencing and comparative genomics, we show that the ooc gene cluster is widespread within biocontrol and phytopathogenic strains of the enterobacteria, Serratia and Dickeya. The analysis of in frame deletion mutants confirmed the role of a hydroxymethylglutaryl-coenzyme A synthase cassette, three flavin-dependent tailoring enzymes, a free-standing acyl carrier protein and two hypothetical proteins in oocydin A biosynthesis. The requirement of the three trans-acting AT domains for the biosynthesis of the macrolide was also demonstrated. Expression of the ooc gene cluster was shown to be positively regulated by an N-acyl-L-homoserine lactone-based quorum sensing system, but operating in a strain-dependent manner. At a post-transcriptional level, the RNA chaperone, Hfq, plays a key role in oocydin A biosynthesis. The Hfq-dependent regulation is partially mediated by the stationary phase sigma factor, RpoS, which was also shown to positively regulate the synthesis of the macrolide. Our results reveal differential regulation of the divergently transcribed ooc transcriptional units, highlighting the complexity of oocydin A production.This research was supported by the EU Marie-Curie Intra-European Fellowship for Career Development (FP7-PEOPLE-2011-IEF) Grant No. 298003. The Salmond laboratory is supported by funding through the Biotechnology and Biological Sciences Research Council, BBSRC (UK). Work with plant pathogens was carried out under DEFRA Licence No. 50864/197900/1.This is the final version of the article. It first appeared from Wiley via http://dx.doi.org/10.1111/1462-2920.1283
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