58,726 research outputs found
COINTEGRATION AND THE FORECAST ACCURACY OF VAR MODELS
This paper assesses the forecast performance of a set of VAR models under a growing number of restrictions. With a maximum forecast horizon of 12 years, we show that the farther the horizon is, the more structured and restricted VAR models have to be to produce accurate forecasts. Indeed, unrestricted VAR models, not subjected to integration or cointegration, are poor forecasters for both short and long run horizons. Differenced VAR models, subject to integration, are reliable predictors for one-step horizons but ineffectual for multi-step horizons. Cointegrated VAR models including appropriate structural breaks and exogenous variables, as well as being subjected to over-identifying theory consistent restrictions, are excellent forecasters for both short and long run horizons. Hence, to obtain precise forecasts from VAR models, proper specification and cointegration are crucial for whatever horizons are at stake, while integration is relevant only for short run horizons.VAR demand systems; structural breaks, exogenous regressors, integration; cointegration; forecast accuracy.
What\u27s in a Name? Racial and Ethnic Classifications and the Meaning of Hispanic/Latino in the United States
The first national census was conducted in 1790, and has been repeated at ten year intervals ever since. While census taking has been consistent, the way individuals have been counted and categorized on the basis of race and ethnicity has varied over time. This paper examines how the official census definition of Latinos has changed over the twenty-two census periods. The modifications of the official definition of this group are discussed in relation to changes in national borders, variations in methodology used for census data gathering, and shifting political contexts
Testing Alternative Dynamic Systems for Modelling Tourism Demand
The goals in this paper are to contribute an empirical study of tourism demand dynamics, and to point out areas where the scrutiny of relationships between theoretical and empirical considerations are likely to produce new insights in this area of research. A flexible general form of a Dynamic Almost Ideal Demand System (DAIDS) is derived to analyse the UK tourism demand for its geographically proximate neighbours Portugal, Spain and France, in the period 1969-1997. Nested within the general dynamic structure are Deaton and Muellbauer’s static AIDS model itself, the partial adjustment model and the auto-regressive distributed lag model, which are tested against the general dynamic alternative. The empirical results obtained show that DAIDS is a data coherent and theoretically consistent model, providing evidence of the robustness of this methodology to conduct tourism demand analysis in a temporal context. Moreover, the dynamic model offers statistically strong evidence on the inadequacy of the orthodox static AIDS and the other restricted models to reconcile consistently data and theory within their formulations. Estimates for tourism price and expenditure elasticities are obtained, permitting a comparative analysis of the relative magnitudes and statistical relevance of long and short run sensitivity of the UK tourism demand to changes in its determinants.Tourism Demand, dynamic almost ideal system, partial adjustment system, autoregressive distributed lag system.
Letter from Matilde M. de Soto and Maria Lydia Sanchez de Roman, Deputies of the Costa Rican Legislative Assembly, to Geraldine Ferraro
Letter from Matilde M. de Soto and Maria Lydia Sanchez de Roman, Deputies of the Costa Rican Legislative Assembly, to Geraldine Ferraro. Letter has handwritten notes and includes a Library of Congress translation.https://ir.lawnet.fordham.edu/vice_presidential_campaign_correspondence_1984_international/1344/thumbnail.jp
New methods for chicken embryo manipulations
The capacity to image a growing embryo while simultaneously studying the developmental function of specific molecules provides invaluable information on embryogenesis. However, until recently, this approach was accomplished with difficulty both because of the advanced technology needed and because an easy method of minimizing damage to the embryo was unavailable. Here, we present a novel way of adapting the well-known EC culture of whole chick embryos to time-lapse imaging and to functional molecular studies using blocking agents. The novelty of our method stems from the ability to apply blocking agents ex ovo as well as in ovo. We were able to study the function of a set of molecules by culturing developing embryos ex ovo in tissue culture media containing these molecules or by injecting them underneath the live embryo in ovo. The in ovo preparation is particularly valuable, because it extends the period of time during which the developmental function of the molecule can be studied and it provides an easy, reproducible method for screening a batch of molecules. These new techniques will prove very helpful in visualizing and understanding the role of specific molecules during embryonic morphogenesis, including blood vessel formation
Nonclassicality and criticality in symmetry-protected magnetic phases
Quantum and global discord in a spin-1 Heisenberg chain subject to single-ion
anisotropy (uniaxial field) are studied using exact diagonalisation and the
density matrix renormalisation group (DMRG). We find that these measures of
quantum nonclassicality are able to detect the quantum phase transitions
confining the symmetry protected Haldane phase and show critical scaling with
universal exponents. Moreover, in the case of thermal states, we find that
quantum discord can increase with increasing temperature.Comment: 7 pages, 6 figures, Close to published version. Includes a link to
data used for the figure
A magnetic reconnection model for explaining the multi-wavelength emission of the microquasars Cyg X-1 and Cyg X-3
Recent studies have indicated that cosmic ray acceleration by a first-order
Fermi process in magnetic reconnection current sheets can be efficient enough
in the surrounds of compact sources. In this work, we discuss this acceleration
mechanism operating in the core region of galactic black hole binaries (or
microquasars) and show the conditions under which this can be more efficient
than shock acceleration. In addition, we compare the corresponding acceleration
rate with the relevant radiative loss rates obtaining the possible energy
cut-off of the accelerated particles and also compute the expected spectral
energy distribution (SED) for two sources of this class, namely Cygnus X-1 and
Cygnus X-3, considering both leptonic and hadronic processes. The derived SEDs
are comparable to the observed ones in the low and high energy ranges. Our
results suggest that hadronic non-thermal emission due to photo-meson
production may produce the very high energy gamma-rays in these microquasars.Comment: 17 pages and 7 figures. Accepted for publication in the Monthly
Notices of the Royal Astronomical Society (MNRAS
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