Search results for "Statistical"
showing 10 items of 4960 documents
Pairing gap and in-gap excitations in trapped fermionic superfluids
2004
We consider trapped atomic Fermi gases with Feshbach-resonance enhanced interactions in pseudogap and superfluid temperatures. We calculate the spectrum of RF(or laser)-excitations for transitions that transfer atoms out of the superfluid state. The spectrum displays the pairing gap and also the contribution of unpaired atoms, i.e. in-gap excitations. The results support the conclusion that a superfluid, where pairing is a many-body effect, was observed in recent experiments on RF spectroscopy of the pairing gap.
How markets slowly digest changes in supply and demand
2008
In this article we revisit the classic problem of tatonnement in price formation from a microstructure point of view, reviewing a recent body of theoretical and empirical work explaining how fluctuations in supply and demand are slowly incorporated into prices. Because revealed market liquidity is extremely low, large orders to buy or sell can only be traded incrementally, over periods of time as long as months. As a result order flow is a highly persistent long-memory process. Maintaining compatibility with market efficiency has profound consequences on price formation, on the dynamics of liquidity, and on the nature of impact. We review a body of theory that makes detailed quantitative pr…
Educación XX1 : revista de la Facultad de Educación
2017
Introducción: La institucionalización del Aprendizaje-Servicio (ApS) en la universidad recomienda, en primer lugar, el análisis de la cultura docente del profesorado y su actitud hacia la innovación. Precisamente, lo que este trabajo pretende es aportar un modelo teórico integrador desarrollando tres escalas de evaluación, contrastadas a través de pruebas estadísticas, para el contexto de la enseñanza universitaria en España. Metodología: A fin de elaborar el modelo de medida se aplicaron tres escalas a 1903 profesoras y profesores de 6 universidades españolas: una escala de práctica docente (18 ítems), otra sobre compromiso social de la Universidad (9 ítems), y una tercera, sobre prácticas…
Falacias sobre el valor p compartidas por profesores y estudiantes universitarios
2017
Resumen La “Práctica Basada en la Evidencia” exige que los profesionales valoren de forma crítica los resultados de las investigaciones psicológicas. Sin embargo, las interpretaciones incorrectas de los valores p de probabilidad son abundantes y repetitivas. Estas interpretaciones incorrectas afectan a las decisiones profesionales y ponen en riesgo la calidad de las intervenciones y la acumulación de un conocimiento científico válido. Identificar el tipo de falacia que subyace a las decisiones estadísticas es fundamental para abordar y planificar estrategias de educación estadística dirigidas a intervenir sobre las interpretaciones incorrectas. En consecuencia, el objetivo de este estudio e…
Misconceptions of the p-value among Chilean and Italian academic psychologists
2016
Common misconceptions of p-values are based on certain beliefs and attributions about the significance of the results. Thus, they affect the professionals' decisions and jeopardize the quality of interventions and the accumulation of valid scientific knowledge. We conducted a survey on 164 academic psychologists (134 Italian, 30 Chilean) questioned on this topic. Our findings are consistent with previous research and suggest that some participants do not know how to correctly interpret p-values. The inverse probability fallacy presents the greatest comprehension problems, followed by the replication fallacy. These results highlight the importance of the statistical re-education of researche…
Combining feature extraction and expansion to improve classification based similarity learning
2017
Abstract Metric learning has been shown to outperform standard classification based similarity learning in a number of different contexts. In this paper, we show that the performance of classification similarity learning strongly depends on the data format used to learn the model. We then present an Enriched Classification Similarity Learning method that follows a hybrid approach that combines both feature extraction and feature expansion. In particular, we propose a data transformation and the use of a set of standard distances to supplement the information provided by the feature vectors of the training samples. The method is compared to state-of-the-art feature extraction and metric lear…
Effects of fourth-order fiber dispersion on ultrashort parabolic optical pulses in the normal dispersion regime
2011
International audience; We propose a new method for the generation of both triangular-shaped optical pulses and flat-top, coherent supercontinuum spectra using the effect of fourth-order dispersion on parabolic pulses in a passive, normally dispersive highly nonlinear fiber. The pulse re-shaping process is described qualitatively and is compared to numerical simulations.
Horseshoe-shaped maps in chaotic dynamics of long Josephson junction driven by biharmonic signals
2000
Abstract A collective coordinate approach is applied to study chaotic responses induced by an applied biharmonic driven signal on the long Josephson junction influenced by a constant dc-driven field with breather initial conditions. We derive a nonlinear equation for the collective variable of the breather and a new version of the Melnikov method is then used to demonstrate the existence of Smale horseshoe-shaped maps in its dynamics. Additionally, numerical simulations show that the theoretical predictions are well reproduced. The subharmonic Melnikov theory is applied to study the resonant breathers. Results obtained using this approach are in good agreement with numerical simulations of …
On the nature of parr functions to predict the most reactive sites along organic polar reactions
2013
Abstract Very recently, local electrophilic and nucleophilic “Parr functions” were empirically introduced (L.R. Domingo, P. Perez, J.A. Saez RSC Adv. 3 (2013) 1486) in order to properly characterize the most reactive sites along polar chemical reactions. This Letter reports a theoretical advance to the new methodology by identifying these quantities with key Fukui descriptors of the spin-polarized density functional theory . Given such framework properly incorporates the treatment of both charge-transfer and spin-polarization, this finding provides a significant insight and substantial step forward within the field of a chemical reactivity theory based on the conceptual framework of density…
Quantum chemistry of the excited state: 2005 overview
2005
The present contribution contains an overview of quantum-chemical methods and strategies to compute and interpret spectroscopic and photochemical phenomena in molecular systems. The state of the art for the quantum chemistry of the excited state is reviewed, focusing in the advantages and disadvantages of the most commonly employed computational methods, from the single configurational procedures like CI-Singles (CIS), propagator approaches, and Coupled-Cluster (CC) techniques, to the more sophisticated multiconfigurational treatments, with particular emphasis on perturbation theory, the CASPT2 approach. Also, a short summary on the performance, lights, and shadows of the popular TDDFT meth…