8,928 research outputs found
Range unit root tests
Since the seminal paper by Dickey and Fuller in 1979, unit-root tests have conditioned the standard approaches to analyse time series with strong serial dependence, the focus being placed in the detection of eventual unit roots in an autorregresive model fitted to the series. In this paper we propose a completely different method to test for the type of "long-wave" patterns observed not only in unit root time series but also in series following more complex data generating mechanism. To this end, our testing device analyses the trend exhibit by the data, without imposing any constraint on the generating mechanism. We call our device the Range Unit Root (RUR) Test since it is constructed from running ranges of the series. These statistics allow a more general characterization of a strong serial dependence in the mean behavior, thus endowing our test with a number of desirable properties. Among these properties are the invariance to nonlinear monotonic transformations of the series and the robustness to the presence of level shifts and additive outliers. In addition, the RUR test outperforms the power of standard unit root tests on near-unit-root stationary time series
A range unit root test
Since the seminal paper by Dickey and Fuller in 1979, unit-root tests have conditioned the standard approaches to analyse time series with strong serial dependence, the focus being placed in the detection of eventual unit roots in an autorregresive model fitted to the series. In this paper we propose a completely different method to test for the type of long-wave patterns observed not only in unit root time series but also in series following more complex data generating mechanisms. To this end, our testing device analyses the trend exhibit by the data, without imposing any constraint on the generating mechanism. We call our device the Range Unit Root (RUR) Test since it is constructed from running ranges of the series. These statistics allow a more general characterization of a strong serial dependence in the mean behavior, thus endowing our test with a number of desirable properties, among which its error-model-free asymptotic distribution, the invariance to nonlinear monotonic transformations of the series and the robustness to the presence of level shifts and additive outliers. In addition, the RUR test outperforms the power of standard unit root tests on near-unit-root stationary time series and is asymptotically immune to noise
A RANGE UNIT ROOT TEST
Since the seminal paper by Dickey and Fuller in 1979, unit-root tests have conditioned the standard approaches to analyse time series with strong serial dependence, the focus being placed in the detection of eventual unit roots in an autorregresive model fitted to the series. In this paper we propose a completely different method to test for the type ofâlong-waveâ patterns observed not only in unit root time series but also in series following more complex data generating mechanisms. To this end, our testing device analyses the trend exhibit by the data, without imposing any constraint on the generating mechanism. We call our device the Range Unit Root (RUR) Test since it is constructed from running ranges of the series. These statistics allow a more general characterization of a strong serial dependence in the mean behavior, thus endowing our test with a number of desirable properties, among which its error-model-free asymptotic distribution, the invariance to nonlinear monotonic transformations of the series and the robustness to the presence of level shifts and additive outliers. In addition, the RUR test outperforms the power of standard unit root tests on near-unit-root stationary time series and is asymptotically immune to noise.
Gaceta Sanitaria al cuidado de las buenas prĂĄcticas en la publicaciĂłn cientĂfica: una experiencia con el Committee on Publication Ethics
Validation and Adaptation of the Prosocial and Antisocial Behavior in Sport Scale to the Spanish context of Physical Education
Physical education (PE), by its own characteristics, is a subject where social communication is especially promoted. However, it is necessary to have tools that evaluate the social behaviour of students during PE classes. For this reason, we propose to validate and adapt the Prosocial and Antisocial Behavior in Sport Scale to the Spanish context of PE classes. The study involved 1081 students aged 12 to 18 (M = 14.83; SD = 1.27). The psychometric properties of the Prosocial Behavior Scale were analyzed through several statistical analyses. The results of the confirmatory factorial analysis and the exploratory factorial analysis supported the internal structure of the questionnaire. In addition, the scale was invariant to gender. Cronbachâs alpha values were higher than 0.70 in the factors and sub-factors, finally showing adequate levels of temporal stability. Taking into account the results achieved in the present study, PE teachers have an effective tool to assess the social and antisocial behaviour of their studentsâ students during PE classes
Inquiry based learning: why buying a car with a tree included? Enhancing science and mathematic learning
International reports reveal a deficient situation in relation to science and mathematics learning, which can be considered as an obstacle for the education of literate and informed citizens and the qualification and the preparation of future scientists and engineers. This situation may be partly attributed to the way science and mathematics are taught at school. Research on effective teaching approaches shows that inquiry based learning (IBL) improves studentsâ engagement and motivation for science and mathematics learning and promotes the development of process skills, critical thinking and conceptual understanding of some science and mathematics topics. The present work describes the design and implementation of an instructional approach for enhancing science and mathematics learning through IBL. The instructional approach is based on the design of an interdisciplinary task which starts by challenging students through the analysis of an advertisement. The initial scenario engages students in an investigation process to look for evidence and understanding while acquiring meaningful learning of key science topics and mathematical tools. The task also takes advantage of current technological resources to facilitate and support the overall inquiry process. (Orig.
La balsa del Barranco del Juncaret (Mutxamel) y otras estructuras hidrĂĄulicas de Ă©poca romana del territorium de Lucentum (Tossal de Manises, Alacant)
Presentamos las conclusiones finales de las campañas de excavación arqueológica realizadas en la balsa de época romana situada en el barranco del Juncaret (término municipal de Mutxamel) y su posible funcionalidad, asà como otras estructuras hidråulicas también de época romana localizadas en los alrededores
Multi-agent simulations for emergency situations in an airport scenario
This paper presents a multi-agent framework using Net- Logo to simulate humanand collective behaviors during emergency evacuations. Emergency situationappears when an unexpected event occurs. In indoor emergency situation, evacuation plans defined by facility manager explain procedure and safety ways tofollow in an emergency situation. A critical and public scenario is an airportwhere there is an everyday transit of thousands of people. In this scenario theimportance is related with incidents statistics regarding overcrowding andcrushing in public buildings. Simulation has the objective of evaluating buildinglayouts considering several possible configurations. Agents could be based onreactive behavior like avoid danger or follow other agent, or in deliberative behaviorbased on BDI model. This tool provides decision support in a real emergencyscenario like an airport, analyzing alternative solutions to the evacuationprocess.Publicad
Incidence and type of bicuspid aortic valve in two model species
Incidence and type of bicuspid aortic
valve in two model species.
MC FernĂĄndez 1,2, A LĂłpez-GarcĂa 1,2, MT Soto 1,
AC DurĂĄn 1,2 and B FernĂĄndez 1,2.
1 Department of Animal Biology, Faculty of Science, University of MĂĄlaga, Spain.
2 Biomedical Research Institute of MĂĄlaga (IBIMA),
University of MĂĄlaga, Spain.
Bicuspid aortic valve (BAV) is the most frequent human congenital cardiac malformation, with an incidence of 1â2% worldwide. Two morphological types exist: type A (incidence 0.75â1.25%) and type B (incidence 0.25â0.5%), each with a distinct aetiology and natural history. Currently, ten animal models of BAV have been described in two different rodent species: one spontaneous Syrian hamster (Mesocricetus auratus) model of BAV type A and nine mutant laboratory mouse (Mus musculus) models of BAV type B. It remains to be elucidated whether the mutations leading to BAV in these models are typespecific or whether there are inter-specific differences regarding the type of BAV that hamsters, mice and humans may develop.
To solve this issue, we have characterized the incidence and types of BAVs in four inbred, two outbred and two hybrid lines of Syrian hamsters (n=4,340) and in three inbred, three outbred and one hybrid lines of laboratory mice (n=1,661) by means of stereomicroscopy and scanning electron microscopy. In addition, we have reviewed and calculated the incidence and type of BAVs in the published papers dealing with this anomaly in mice.
Our results indicate that the Syrian hamster develops BAVs type A and B including a variety of morphologies comparable to those of humans, whereas the mouse develops only BAVs type B with a short spectrum of valve morphologies. Thus, inter-specific differences between human and mouse aortic valves must be taken into consideration when studying valve disease in murine models.
This work was supported by P10-CTS-6068.Universidad de MĂĄlaga. Campus de Excelencia Internacional AndalucĂa Tech. P10-CTS-6068
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