Home About us Contact
|
Home About us Contact | ||
|
|
||
Traditional Methodology (traditional + methodology)
Selected AbstractsCan forecasting performance be improved by considering the steady state?JOURNAL OF FORECASTING, Issue 1 2008An application to Swedish inflation, interest rate Abstract This paper investigates whether the forecasting performance of Bayesian autoregressive and vector autoregressive models can be improved by incorporating prior beliefs on the steady state of the time series in the system. Traditional methodology is compared to the new framework,in which a mean-adjusted form of the models is employed,by estimating the models on Swedish inflation and interest rate data from 1980 to 2004. Results show that the out-of-sample forecasting ability of the models is practically unchanged for inflation but significantly improved for the interest rate when informative prior distributions on the steady state are provided. The findings in this paper imply that this new methodology could be useful since it allows us to sharpen our forecasts in the presence of potential pitfalls such as near unit root processes and structural breaks, in particular when relying on small samples.,,Copyright © 2008 John Wiley & Sons, Ltd. [source] Improved synthesis of DOTA tetraamide ligands for lanthanide(III) ions: A tool for increasing the repertoire of potential PARACEST contrast agents for MRI and/or fluorescent sensorsCONTRAST MEDIA & MOLECULAR IMAGING, Issue 3 2010Luis M. De León-Rodríguez Abstract The synthesis of new DOTA tetraamide (DOTAMR4) compounds is of great interest given their application in the formation of Ln(III) complexes as potential PARACEST contrast agents in MRI or fluorescent molecular probes. In this context amino acid and peptide DOTAMR4 derivatives are particularly attractive since the amino-acid and/or peptide moiety can show responsive properties dependent on a given stimuli which might translate to changes in water exchange rates of the corresponding Ln(III) complex. Current synthesis of DOTAMR4 derivatives is typically carried out by reacting haloacetamide intermediates with cyclen. However, this method fails to generate the tetra-substituted products when bulky substituents are present in the haloacetamide and in some cases this intermediate cannot be prepared by conventional acylation procedures limiting the number of DOTAMR4 compounds available for study. As a solution to these limitations, an improved methodology for the synthesis of DOTAMR4 by coupling DOTA to an appropriate amine containing reagent (i.e. protected amino-acids with the , -amino group free) is presented in this work. Several DOTAMR4 derivatives which are difficult or impossible to prepare with the traditional methodologies were easily obtained starting with DOTA. A new protocol was derived using this methodology for the solution-phase synthesis of DOTA peptide derivatives. With this methodology, many other DOTAMR4 peptide and non-peptide derivatives have been prepared in our laboratories with several of these new compounds showing interesting properties for molecular imaging. Copyright © 2010 John Wiley & Sons, Ltd. [source] Identification of the endangered small red brocket deer (Mazama bororo) using noninvasive genetic techniques (Mammalia; Cervidae)MOLECULAR ECOLOGY RESOURCES, Issue 3 2009SUSANA GONZÁLEZ Abstract The small red brocket deer Mazama bororo is one of the most endangered deer in the Neotropics. The great morphological similarities with three other sympatric brocket deer species, coupled with the fact that they inhabit densely forested habitats complicate detection and prevent the use of traditional methodologies for accurate identification of species. The ability to determine the presence of this endangered species in an area is crucial for estimating its distribution range, and is critical for establishing conservation management strategies. Here we describe a fast and reliable noninvasive genetic method for species identification of Mazama species from faeces. We designed a primer set that amplifies a short 224-bp fragment of the cytochrome b and demonstrate its effectiveness in successful amplification of DNA isolated from both tissue and faecal samples. This fragment contains a BSTNI/ECORII digestion site that is unique to the endangered M. bororo. The digested polymerase chain reaction products yielded a 160-bp fragment that is clearly visible in a 2% agarose gel. Two other diagnostic sites were identified to differentiate the other three sympatric species, SspI (M. gouazoubira) and AflIII (M. americana, and M. nana). [source] Estimating the long memory granger causality effect with a spectrum estimatorJOURNAL OF FORECASTING, Issue 3 2006Wen-Den ChenArticle first published online: 11 APR 200 Abstract This paper discusses the Granger causality test by a spectrum estimator which allows the transfer function to have long memory properties. In traditional methodology the relationship among variables is usually assumed to be short memory or contemporaneous. Hence, we have to make sure they are of the same integrated order, else there might be a spurious regression problem. In practice, not all the variables are fractionally co-integrated in the economic model. They may have the same random resources, but under a different integrated order. This paper focuses on how to capture the long memory Granger causality effect in the transfer function. This does not necessarily assume the variables are of the same fractional integrated order. Moreover, by the transfer function we construct an estimator to test the long memory effect with the Granger causality sense. Copyright © 2006 John Wiley & Sons, Ltd. [source] Deterministic and statistical methods for reconstructing multidimensional NMR spectra,MAGNETIC RESONANCE IN CHEMISTRY, Issue 3 2006Ji Won Yoon Abstract Reconstruction of an image from a set of projections is a well-established science, successfully exploited in X-ray tomography and magnetic resonance imaging. This principle has been adapted to generate multidimensional NMR spectra, with the key difference that, instead of continuous density functions, high-resolution NMR spectra comprise discrete features, relatively sparsely distributed in space. For this reason, a reliable reconstruction can be made from a small number of projections. This speeds the measurements by orders of magnitude compared to the traditional methodology, which explores all evolution space on a Cartesian grid, one step at a time. Speed is of crucial importance for structural investigations of biomolecules such as proteins and for the investigation of time-dependent phenomena. Whereas the recording of a suitable set of projections is a straightforward process, the reconstruction stage can be more problematic. Several practical reconstruction schemes are explored. The deterministic methods,additive back-projection and the lowest-value algorithm,derive the multidimensional spectrum directly from the experimental projections. The statistical search methods include iterative least-squares fitting, maximum entropy, and model-fitting schemes based on Bayesian analysis, particularly the reversible-jump Markov chain Monte Carlo procedure. These competing reconstruction schemes are tested on a set of six projections derived from the three-dimensional 700-MHz HNCO spectrum of a 187-residue protein (HasA) and compared in terms of reliability, absence of artifacts, sensitivity to noise, and speed of computation. Copyright © 2006 John Wiley & Sons, Ltd. [source] New method for age estimation of developmental defects of enamel formation in living populationsAMERICAN JOURNAL OF HUMAN BIOLOGY, Issue 4 2010Rhonda Gillett-Netting Histologically based age of occurrence estimates for developmental defects of enamel (DDE) are raising questions about the continued utility of traditional macroscopic methods; however, the new techniques are not appropriate for use on living populations. This study, using methodology suitable for noninvasive use on living populations, compares assignment of defect timing using a histologically informed macroscopic method (HIMM) versus traditional methodology (TM). For this Southern African population, TM estimates later median age of DDE occurrence than HIMM (Z -score: ,13.565, P < 0.000) and modal age is 1 year earlier. HIMM allows for continued collection of DDE in living populations with the added benefit of more precise timing of enamel development. Accuracy for estimating general stressors during childhood is necessary for construction of diachronic analyses. Am. J. Hum. Biol., 2010. © 2010 Wiley-Liss, Inc. [source] | ||||||||||