The relative importance of Term Spread, Policy Inertia and Persistent Monetary Policy Shocks in Monetary Policy Rules

This paper estimates a standard version of the New Keynesian Monetary Model (NKM) augmented with the term structure in order to analyze two types of issue. First we analyse the relative importance of policy inertia, persistent policy shocks and the term spread in the estimated US monetary policy rule. Second, we study the ability of the model to reproduce some stylized facts such as high persistent dynamics and the weak comovement between economic activity and inflation observed in actual US data. The estimation procedure implemented is a classical structural method based on the indirect inference principle. The empirical results show that (i) policy intertia, persistent policy shocks and the term spread are all significant determinants in the estimated US monetary policy rule, (ii) the Fed responds to the information content of the spread about future inflation and real activity, but the Fed does not seem to respond independently to the spread; and (iii) the model augmented with term structure reproduces the weak comovement between economic activity and inflation as well as the strong comovement at medium and long-term forecast horizons between the Fed rate and the 1-yar rate observed in the US datNKM model, term structure, monetary policy rule

Dynamical generation of wormholes with charged fluids in quadratic Palatini gravity

The dynamical generation of wormholes within an extension of General Relativity (GR) containing (Planck's scale-suppressed) Ricci-squared terms is considered. The theory is formulated assuming the metric and connection to be independent (Palatini formalism) and is probed using a charged null fluid as a matter source. This has the following effect: starting from Minkowski space, when the flux is active the metric becomes a charged Vaidya-type one, and once the flux is switched off the metric settles down into a static configuration such that far from the Planck scale the geometry is virtually indistinguishable from that of the standard Reissner-Nordstr\"om solution of GR. However, the innermost region undergoes significant changes, as the GR singularity is generically replaced by a wormhole structure. Such a structure becomes completely regular for a certain charge-to-mass ratio. Moreover, the nontrivial topology of the wormhole allows to define a charge in terms of lines of force trapped in the topology such that the density of lines flowing across the wormhole throat becomes a universal constant. To the light of our results we comment on the physical significance of curvature divergences in this theory and the topology change issue, which support the view that space-time could have a foam-like microstructure pervaded by wormholes generated by quantum gravitational effects.Comment: 14 pages, 3 figures, revtex4-1 style. New content added on section VI. Other minor corrections introduced. Final version to appear in Phys. Rev.

Spin and exchange coupling for Ti embedded in a surface dipolar network

We have studied the spin and exchange coupling of Ti atoms on a Cu$_2$N/Cu(100) surface using density functional theory. We find that individual Ti have a spin of 1.0 (i.e., 2 Bohr Magneton) on the Cu$_2$N/Cu(100) surface instead of spin-1/2 as found by Scanning Tunneling Microscope. We suggest an explanation for this difference, a two-stage Kondo effect, which can be verified by experiments. By calculating the exchange coupling for Ti dimers on the Cu$_2$N/Cu(100) surface, we find that the exchange coupling across a `void' of 3.6\AA\ is antiferromagnetic, whereas indirect (superexchange) coupling through a N atom is ferromagnetic. We confirm the existence of superexchange interactions by varying the Ti-N angle in a model trimer calculation. For a square lattice of Ti on Cu$_2$N/Cu(100), we find a novel spin striped phase

Bayesian acoustic prediction assimilating oceanographic and acoustically inverted data

The prediction of the transmission loss evolution on a day to week frame, in a given oceanic area, is an important issue in modeling the sonar performance. It relies primarily on acoustic propagation models, which convert water column and geometric/ geoacoustic parameters to ‘instantaneous’ acoustic field estimates. In practice, to model the acoustic field, even the most accurate acoustic models have to be fed with simplified environmental descriptions, due to computational issues and to a limited knowledge of the environment. This is a limitation, for example, in acoustic inversion methods, in which, by maximizing the proximity between measured and modeled acoustic signals, the estimated environmental parameters are deviated from reality, forming what is normally called an ‘acoustically equivalent environment’. This problem arises also in standard acoustic prediction, in which, the oceanographic forecasts and bottom data (typically from archives) are fed directly to an acoustic model. The claim in the present work is that, by converting the oceanographic prediction and the bottom properties to ‘acoustically equivalent’ counterparts, the acoustic prediction can be obtained in an optimal way, adapted to the environmental model at hand. Here, acoustic prediction is formulated as a Bayesian estimation problem, in which, the observables are oceanographic forecasts, a set of known bottom parameters, a set of acoustic data, and a set of water column data. The predictive posterior PDF of the future acoustic signal is written as a function of elementary PDF functions relating these observables and ‘acoustically equivalent’ environmental parameters. The latter are obtained by inversion of acoustic data. The concept is tested on simulated data based on water column measurements and forecasts for the MREA’03 sea trial.We thank the partial funding of Funda¸c˜ao para a Ciˆencia e Tecnologia - FCT under POSI, POCTI and POCI programs, and scholarship no. SFRH/BD/9032/2002. Acknowledgements are addressed also to Emanuel Coelho, for conducing the MREA’03 sea trial, and to Peter Gerstoft, for prompt help and improvements of the SAGA inversion package

Blind channel estimation with data from the INTIMATE'96 sea trial

Blind multipath channel estimation is studied by time-frequency (TF) analysis. For a linear frequency modulated source, the technique is based on its instantaneous frequency estimation, followed by an approximate formulation of matched- ltering. Tests concern at-sea recorded data during the INTIMATE '96 experiment.Thanks are due to the INTIMATE '96 team for the real data acquisition, to FCT, for funding, under fellowship PRAXIS XXI (BM/19298/99), and to A. Quinquis and C. Gervaise for the valuable reception at ENSIETA

From oceanographic to acoustic forecasting: acoustic model calibration using in situ acoustic measures

Sonar performance prediction relies heavily on acoustic propagation models and environmental representations of the oceanic area in which the sonar is to operate. The performance estimate is derived from a predicted acoustic eld, which is the output of a propagation model. Though well developed nowadays, acoustic propagation modeling is limited in practice by simpli cations in the numerical methods, in the environmental structure to consider (for computational reasons), and even in the knowledge of some environmental properties. This is complicated by the fact that, in sonar performance prediction, the environmental properties need to be predicted for a far future, in the order of hours or days. These limitations imply that the acoustic eld at the output of the acoustic predictor is biased, in current methods. In mathematical terms, the prediction of the acoustic eld can be seen as a model parametrization problem, in which the model is a numerical propagation model, and the parameters are environmental descriptors which, when fed to the propagation model, best model the future acoustic field. Since the 1980's, signi cant research has been done in the development of propagation model parametrization, using techniques of the so-called \acoustic inversion" family. These techniques, having as objective the estimation of environmental properties of an oceanic area, use observed acoustic elds at the area, to be matched with candidate elds corresponding to candidate environmental pictures. At the end, the best acoustic match gives the estimated environment, in other words, the best model parameters to closely reproduce the measured acoustic eld. In the current work, the technique of acoustic inversion is used in the design of an acoustic predictor, together with oceanographic forecasts and measures. Synthetic acoustic data generated with oceanographic measures taken in the MREA'03 sea trial, is used to illustrate the proposed method. The results show that a collection of environments estimated by past acoustic inversions, can ameliorate the acoustic estimates for future time, as compared to a conventional method

Volatile compound diversity and conserved alarm behaviour in Triatoma dimidiata

Background: Triatoma dimidiata (Latreille) is a key vector complex of Trypanosoma cruzi, etiologic agent of Chagas disease, as it spans North, Central, and South America. Although morphological and genetic studies clearly indicate existence of at least five clades within the species, there has been no robust or systematic revision, or appropriate nomenclature change for species within the complex. Three of the clades (haplogroups) are distributed in Mexico, and recent evidence attests to dispersal of clades across previously "presumed"monotypic geographic regions. Evidence of niche conservatism among sister species of this complex suggests that geographic dispersal is possible for non-sympatric populations, although no information is available on the behavioural aspects of potential interclade interactions, for instance whether differentiation of chemical signaling or response to these signals could impede communication among the haplogroups. Methods: Volatiles emitted by disturbed bugs, Brindley's (BGs), and metasternal (MGs) glands were identified using solid-phase micro-extraction (SPME) and gas chromatography coupled mass spectrometry (GC-MS). Volatile compounds emitted by BGs and MGs, and those secreted by disturbed nymphs and adults, of the three Mexican T. dimidiata haplogroups were tested for avoidance behaviour by conspecific nymphs and adults using an olfactometer. Results: Triatoma dimidiata haplogroups all have three age-related alarm responses: absence of response by early stage nymphs, stage-specific response by 4-5th stage nymphs, and a shared 4-5th nymph and adult response to adult compounds. Disturbed bugs released 15 to 24 compounds depending on the haplogroup, among which were three pyrazines, the first report of these organoleptics in Triatominae. Isobutyric acid from BGs was the most abundant molecule in the response in all haplogroups, in addition to 15 (h1) to 21 (h2 and h3) MG compounds. Avoidance behaviour of disturbed bugs and volatiles emitted by BGs were haplogroup specific, while those from the MG were not. Conclusions: Discriminant and cluster analysis of BG +MG compounds indicate significant separation among the three haplogroups, while alarm response compounds were similar between h2 and h3, both distinct from h1. This latter haplogroup is ancestral phylogenetically to the other two. Our results suggest that alarm responses are a conserved behaviour in the Triatoma dimidiata complex.Fil: May Concha, Irving Jesus. Provincia de Entre Ríos. Centro de Investigaciones Científicas y Transferencia de Tecnología a la Producción. Universidad Autónoma de Entre Ríos. Centro de Investigaciones Científicas y Transferencia de Tecnología a la Producción. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Centro de Investigaciones Científicas y Transferencia de Tecnología a la Producción; Argentina. Instituto Nacional de Salud Pública; MéxicoFil: Rojas, Julio C.. El Colegio de la Frontera Sur; MéxicoFil: Cruz López, Leopoldo. El Colegio de la Frontera Sur; MéxicoFil: Ibarra-Cerdeña, Carlos N.. Instituto Politécnico Nacional. Centro de Investigación y de Estudios Avanzados; MéxicoFil: Ramsey, Janine. Instituto Nacional de Salud Pública; Méxic