An efficient estimator for locally stationary Gaussian long-memory processes

This paper addresses the estimation of locally stationary long-range dependent processes, a methodology that allows the statistical analysis of time series data exhibiting both nonstationarity and strong dependency. A time-varying parametric formulation of these models is introduced and a Whittle likelihood technique is proposed for estimating the parameters involved. Large sample properties of these Whittle estimates such as consistency, normality and efficiency are established in this work. Furthermore, the finite sample behavior of the estimators is investigated through Monte Carlo experiments. As a result from these simulations, we show that the estimates behave well even for relatively small sample sizes.Comment: Published in at http://dx.doi.org/10.1214/10-AOS812 the Annals of Statistics (http://www.imstat.org/aos/) by the Institute of Mathematical Statistics (http://www.imstat.org

The Burdwood Bank Circulation

A suite of high-resolution numerical simulations characterizes the oceanic circulation in the Burdwood Bank, a shallow seamount located in the northeastern end of the Drake Passage. Model analysis shows energetic upwelling and mixing uplifting deep and benthic waters into the photic layer. Tides and the Antarctic Circumpolar Current are the primary drivers of the bank's circulation. Tidal forcing is the main driver for the entrainment of deep waters into the upper layers of the bank and local wind forcing for the detrainment of these waters into the deep ocean. Passive tracer diagnostics suggest that the dynamical processes triggered by the Burdwood Bank could have a significant impact on local ecosystems and the biogeochemical balance of the southwestern Atlantic region, which is one of the most fertile portions of the Southern Ocean. Model results are robust—they are reproduced in a wide array of model configurations—but there is insufficient observational evidence to corroborate them. Satellite color imagery does not show substantial chlorophyll blooms in this region but it shows strong phytoplankton plumes emanating from the bank. There are several potential explanations for the chlorophyll deficit, including lack of light due to persistent cloud cover, deep mixing layers, fast ocean currents, and the likelihood that blooms, while extant, might not develop on the surface. None of these possibilities can be confirmed at this stage.Fil: Matano, Ricardo P.. State University of Oregon; Estados UnidosFil: Palma, Elbio Daniel. Universidad Nacional del Sur. Departamento de Física; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto Argentino de Oceanografía. Universidad Nacional del Sur. Instituto Argentino de Oceanografía; ArgentinaFil: Combes, Vincent. State University of Oregon; Estados Unido

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Multimodal Neuroergonomic Approaches to Human Behavior and Cognitive Workload in Complex High-Risk Semantically Rich Environments: A Case Study of Local & En-Route Air Traffic Controllers

Fast-paced technology advancements have enabled us to create ecologically valid simulations of high risk, complex, and semantically rich environments in which human interaction and decision-making are the keys to increase system performance. These advances have improved our capabilities of exploring, quantifying, and measuring the underlying mechanisms that guide human behavior using sophisticated neuroergonomic devices; and in turn, improve human performance and reduce human errors. In this thesis, multimodal approaches consisted of a self-report analysis, eye-tracking analysis, and functional near-infrared spectroscopy analysis were used to investigate how veteran local & en-route air traffic controllers carry out their operational tasks. Furthermore, the correlations among the cognitive workload and physiological measures (i.e. eye movement characteristics and brain activities) were investigated. Combining the results of these experiments, we can observe that the multimodal approaches show promise on exploring the underlying mechanisms of workload and human interaction in a complex, high-risk, and semantically rich environment. This is because cognitive workload can be considered as a multidimensional construct and different devices or approaches might be more effective in sensing changes in either the task difficulty or complexity. The results can be used to find ways to better train the novices

The influence of the Brazil and Malvinas Currents on the Southwestern Atlantic Shelf Circulation

The oceanic circulation over the southwestern Atlantic shelf is influenced by large tidal amplitudes, substantial freshwater discharges, high wind speeds and – most importantly – by its proximity to two of the largest western boundary currents of the world ocean: the Brazil and Malvinas currents. This review article aims to discriminate the dynamical processes controlling the interaction between this extensive shelf region and the deep-ocean. The discussion is focused on two broad regions: the South Brazil Bight to the north, and Patagonia to the south. The exchanges between the Brazil Current and the South Brazil Bight are characterized by the intermittent development of eddies and meanders of the Brazil Current at the shelfbreak. However, it is argued that this is not the only – nor the most important – influence of the Brazil Current on the shelf. Numerical simulations show that the thermohaline structure of the South Brazil Bight can be entirely ascribed to steady state, bottom boundary layer interactions between the shelf and the Brazil Current. The Malvinas Current does not show the development of eddies and meanders, but its influence on the Patagonian shelf is not less important. Models and observations indicate that the Malvinas Current not only controls the shelfbreak dynamics and cross-shelf exchanges but also influences the circulation in the shelf's interior.Fil: Matano, Ricardo. Oregon State University; Estados UnidosFil: Palma, Elbio Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto Argentino de Oceanografía. Universidad Nacional del Sur. Instituto Argentino de Oceanografía; Argentina. Universidad Nacional del Sur; ArgentinaFil: Piola, Alberto Ricardo. Ministerio de Defensa. Armada Argentina. Servicio de Hidrografía Naval. Centro Arg.de Oceanografía; Argentina. Universidad de Buenos Aires; Argentin

A Numerical Study of the Magellan Plume

In this modeling study we investigate the dynamical mechanisms controlling the spreading of the Magellan Plume, which is a low-salinity tongue that extends along the Patagonian Shelf. Our results indicate that the overall characteristics of the plume (width, depth, spreading rate, etc.) are primarily influenced by tidal forcing, which manifests through tidal mixing and tidal residual currents. Tidal forcing produces a homogenization of the plume’s waters and an offshore displacement of its salinity front. The interaction between tidal and wind-forcing reinforces the downstream and upstream buoyancy transports of the plume. The influence of the Malvinas Current on the Magellan Plume is more dominant north of 50S, where it increases the along-shelf velocities and generates intrusions of saltier waters from the outer shelf, thus causing a reduction of the downstream buoyancy transport. Our experiments also indicate that the northern limit of the Magellan Plume is set by a high salinity discharge from the San Matias Gulf. Sensitivity experiments show that increments of the wind stress cause a decrease of the downstream buoyancy transport and an increase of the upstream buoyancy transport. Variations of the magnitude of the discharge produce substantial modifications in the downstream penetration of the plume and buoyancy transport. The Magellan discharge generates a northeastward current in the middle shelf, a recirculation gyre south of the inlet and a region of weak currents father north.Fil: Palma, Elbio Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto Argentino de Oceanografía. Universidad Nacional del Sur. Instituto Argentino de Oceanografía; Argentina. Universidad Nacional del Sur; ArgentinaFil: Matano, Ricardo. Oregon State University; Estados Unido

La reacción institucionalista : un estudio sobre la heterodoxia económica en los Estados Unidos de América

El artículo estudia el nacimiento y la trayectoria del institucionalismo económico en su etapa formativa. Se analizan sus fundamentos y temas principales junto a sus autores más relevantes. Para comprender la unidad intelectual de un grupo aparentemente heterogéneo, se sostiene que la historia del institucionalismo económico debe ser interpretada bajo el análisis de los contextos de investigación y la figura de un movimiento económico. Se concluye que este último posee rasgos de heterodoxia frente a la corriente principal de la ciencia económica.The article studies the beginning and the path of the economic institutionalism in its formative stage. It will be analyzed its roots, main issues and more relevant authors. In order to understand the intellectual unity of a group that seems to be heterogeneous, it is stated that the institutionalist history must be understood from the research contexts and the economic movement figure approaches. It is concluded that the institutionalist approach has heterodox features compared with the economics mainstream.Fil: Masera, Gustavo Alberto. Universidad del AconcaguaFil: Palma, Ricardo. Universidad Nacional de Cuyo. Facultad de Ingenierí

The lice of the Tristan da Cunha Archipelago (Insecta: Phthiraptera).

In der Arbeit sind alle bisher in der Literatur erwähnten und fünf neu gesammelte bzw. in Sammlungen nachgewiesene Laus-Arten der Tristan da Cunha Inseln aufgelisted und diskutiert. Die Liste umfasst 54 Laus-Arten aus 21 Gattungen mit ihren Wirten, nämlich 20 Vogel-Arten und einem Säugetier und Angaben zu den vier Hauptinseln. Dabei konnten sechs Funde nur bis zur Art bzw. Unterart bestimmt werden. Die Geschichte der Sammlungen auf dem Archipel und der umgebenden Region ist ebenfalls aufgeführt.StichwörterPhthiraptera, Tristan da Cunha, Nightingale, Inaccessible, Gough, South Atlantic Ocean, seabirds, landbirds.All the louse species reported in the literature from the Tristan da Cunha archipelago have been compiled, listed and discussed, including five additional species records based on material recently collected or identified in previous collections. A total of 54 louse species (including 6 records identified at the generic or subgeneric level only), belonging to 21 genera, have been listed together with their hosts: 20 bird species and one mammal. A brief discussion on the history of louse collections made on and around the archipelago, and detailed louse records from the four main islands are also given.KeywordsPhthiraptera, Tristan da Cunha, Nightingale, Inaccessible, Gough, South Atlantic Ocean, seabirds, landbirds

An idealized study of near equatorial river plumes

The dynamics of near equatorial river plumes (NERPs) are investigated using a highly idealized model. The spreading of a NERP from an eastern boundary is characterized by a continuous shedding of westward propagating eddies. This process transfers the bulk of the freshwater discharge to the deep ocean, thus distinguishing NERPs from their midlatitude counterparts. In the long-term limit, a NERP can be rationalized as a β-plume emanating from a coastal source. The evolution of NERPs in an unstratified basin is quite different from that in a stratified one. The spin-up in an unstratified basin is characterized by the formation of an anticyclonic bulge, which spreads westward thus creating a density stratification that favors the subsequent development of smaller and faster moving secondary eddies. The collision of the secondary eddies with the leading bulge arrests the effects of mixing thus allowing the further spreading of the buoyancy anomaly. In a stratified basin, the generation of anticyclonic eddies is accompanied by a concurrent generation of cyclones, which pump saltier waters to the surface hence leading to smaller sea surface salinity (SSS) anomalies. NERPs are sensitive to variations of the freshwater flux (Qfw) and the geomorphological setting. Larger Qfw generates bigger eddies, which spread at a rate proportional to the square root of the normalized flux. Wide shelves allow the interaction of the eddies with the bottom, thus promoting a cyclonic shift of the axis of the eddy train. The inclination of the coast affects the dynamical balance controlling the near-field behavior of NERPs.Fil: Palma, Elbio Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto Argentino de Oceanografía. Universidad Nacional del Sur. Instituto Argentino de Oceanografía; Argentina. Universidad Nacional del Sur. Departamento de Física; ArgentinaFil: Matano, Ricardo. State University of Oregon; Estados Unido