Individual and time effects in nonlinear panel models with large N, T

We derive fixed effects estimators of parameters and average partial effects in (possibly dynamic) nonlinear panel data models with individual and time effects. They cover logit, probit, ordered probit, Poisson and Tobit models that are important for many empirical applications in micro and macroeconomics. Our estimators use analytical and jackknife bias corrections to deal with the incidental parameter problem, and are asymptotically unbiased under asymptotic sequences where N/T converges to a constant. We develop inference methods and show that they perform well in numerical examples.https://arxiv.org/abs/1311.7065Accepted manuscrip

Nonlinear Factor Models for Network and Panel Data

Factor structures or interactive effects are convenient devices to incorporate latent variables in panel data models. We consider fixed effect estimation of nonlinear panel single-index models with factor structures in the unobservables, which include logit, probit, ordered probit and Poisson specifications. We establish that fixed effect estimators of model parameters and average partial effects have normal distributions when the two dimensions of the panel grow large, but might suffer of incidental parameter bias. We show how models with factor structures can also be applied to capture important features of network data such as reciprocity, degree heterogeneity, homophily in latent variables and clustering. We illustrate this applicability with an empirical example to the estimation of a gravity equation of international trade between countries using a Poisson model with multiple factors.Comment: 49 pages, 6 tables, the changes in v4 include numerical results with more simulations and minor edits in the main text and appendi

Higher Order Approximation to the Hill Problem Dynamics about the Libration Points

An analytical solution to the Hill problem Hamiltonian expanded about the libration points has been obtained by means of perturbation techniques. In order to compute the higher orders of the perturbation solution that are needed to capture all the relevant periodic orbits originated from the libration points within a reasonable accuracy, the normalization is approached in complex variables. The validity of the solution extends to energy values considerably far away from that of the libration points and, therefore, can be used in the computation of Halo orbits as an alternative to the classical Lindstedt-Poincar\'e approach. Furthermore, the theory correctly predicts the existence of the two-lane bridge of periodic orbits linking the families of planar and vertical Lyapunov orbits.Comment: 28 pages, 8 figure

Reconstructing the South Pacific upper water conditions during the Late Quaternary

PP11B-1780: The Antarctic Circumpolar Current system (ACCs) is the most important current system in the Southern Ocean, characterized by strong zonal variations in specific surface water properties, variations used to classify regions whose edges are defined by fronts. The past changes in the strength and latitudinal position of the ACC frontal system are supposed to play a major role on the global oceanic circulation and thus the Earth’s climate through their impact on atmospheric CO2 contents by changes in water stratification conditions, Therefore the study of variability in the surface characteristics of the ACCs provides crucial information to understand and to reconstruct the global climate evolution. The dynamics of the upper-ocean vertical structure, primarily defined by vertical changes in salinity and temperature from the mixed layer down to the seasonal and permanent thermocline, can be tracked using the differences in stable oxygen isotopes (__18O) and Mg/Ca-based temperatures (_T) recorded in the test of planktic foraminifera. Only Mg/Ca thermometry coupled with _18O can guarantee a common source of signal, averaging the same environmental conditions (season and spatial habitat), where, the combined measurements of Mg/Ca and _18O allow to extract the _18O record of past upper ocean water, and accordingly salinity variations In this study we present paired measurements of Mg/Ca and stable oxygen isotopes of shallow-living and deeper-living planktic foraminifera preserved in core top and downcore samples from the South Pacific (36° to 45° S) retrieved during the SOPATRA cruise (South Pacific Paleoceanographic Transect) Chile-New Zealand. The total Mg/Ca values preserved in the foraminiferal calcite from 31 core top samples ranged from ~2 to 1.3 mmol/mol, allowing estimate SSTs between 16° and 12° C. Additionally, to evaluate the reliability of the Mg/Ca signal paleothermometry for long term reconstruction we determined the effect of calcite saturation state (_CO32-) into on foraminiferal Mg/Ca concentration in the different selected species. In order to track the upper water column dynamics and strength of the ACC during the last ~200 kyr, we will test our calibration on downcore records gravity cores SO213-59-2 and SO213-60-2 retrieved from the northern border of the Subantarctic Zone (SAZ) of the East Pacific Rise

Enriching ontological user profiles with tagging history for multi-domain recommendations

Many advanced recommendation frameworks employ ontologies of various complexities to model individuals and items, providing a mechanism for the expression of user interests and the representation of item attributes. As a result, complex matching techniques can be applied to support individuals in the discovery of items according to explicit and implicit user preferences. Recently, the rapid adoption of Web2.0, and the proliferation of social networking sites, has resulted in more and more users providing an increasing amount of information about themselves that could be exploited for recommendation purposes. However, the unification of personal information with ontologies using the contemporary knowledge representation methods often associated with Web2.0 applications, such as community tagging, is a non-trivial task. In this paper, we propose a method for the unification of tags with ontologies by grounding tags to a shared representation in the form of Wordnet and Wikipedia. We incorporate individuals' tagging history into their ontological profiles by matching tags with ontology concepts. This approach is preliminary evaluated by extending an existing news recommendation system with user tagging histories harvested from popular social networking sites

Localization of fermions in different domain wall models

Localization of fermions is studied in different gravitational domain wall models. These are generalizations of the brane-world models considered by Randall and Sundrum, but which also allow gravitational localization. Therefore, they might be considered as possible realistic scenarios for phenomenology.Comment: RevTeX, 6 pages, 10 figure

Network and Panel Quantile Effects Via Distribution Regression

This paper provides a method to construct simultaneous confidence bands for quantile functions and quantile effects in nonlinear network and panel models with unobserved two-way effects, strictly exogenous covariates, and possibly discrete outcome variables. The method is based upon projection of simultaneous confidence bands for distribution functions constructed from fixed effects distribution regression estimators. These fixed effects estimators are debiased to deal with the incidental parameter problem. Under asymptotic sequences where both dimensions of the data set grow at the same rate, the confidence bands for the quantile functions and effects have correct joint coverage in large samples. An empirical application to gravity models of trade illustrates the applicability of the methods to network data.Comment: 71 pages, 8 figures, 3 tables, includes supplementary appendi

Comparación de técnicas para el aislamiento y recuento de levaduras y hongos dimórficos del filoplano de Nothofagus pumilio

El filoplano es un importante hábitat de microorganismos. Este trabajo tuvo como objetivo probar distintos métodos para el aislamiento de levaduras y hongos dimórficos del filoplano de Nothofagus pumilio, la especie arbórea dominante de Patagonia. Los métodos probados fueron la impresión sobre medio sólido, agitación vertical con agua durante distintos tiempos, con la adición de surfactante (Tween 80) o abrasivos (arena); macerado y ultrasonido. Se estableció un método que combina la agitación vertical con la aplicación de ultrasonido como metodología apropiada para el aislamiento y recuento. Con este método se determinó que la densidad de levaduras y hongos dimórficos en el filoplano de N. pumilio osciló entre las 10 y 103 unidades formadoras de colonias sobre cm2, valores entre 10 y 100 veces inferiores a los observados para otras especies arbóreas. También se estableció al hongo dimórfico Aureobasidium pullulans como la especie dominante de este ambiente.Comparison of techniques for isolation and enumeration of yeast and yeast like fungi from Nothofagus pumilio phylloplane. The phylloplane is an important habitat for microorganisms. This study aimed to test different methods for the isolation of yeasts and dimorphic fungi from the phylloplane of Nothofagus pumilio, the dominant tree species in Patagonia. The tested methods included printing on agar, vertical agitation on water, with the addition of surfactant compounds (Tween 80) or abrasive material (sand), maceration and ultrasound treatment. A method that combines the vertical agitation, with application of ultrasound was established as the most appropriated for the isolation and enumeration. With this method it was determined that the density of yeasts and dimorphic fungi in the phylloplane of N. pumilio ranged between 10 and 103 colony forming units per cm2, values between 10 and 100 times lower than those observed for other tree species. Also, the dimorphic fungi Aureobasidium pullulans was determined as the dominant fungal species in this environment.Fil: Muñoz, Mario Iván. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Patagonia Norte. Instituto de Investigación en Biodiversidad y Medioambiente; ArgentinaFil: Moline, Martin. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Patagonia Norte. Instituto de Investigación en Biodiversidad y Medioambiente; ArgentinaFil: Libkind Frati, Diego. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Patagonia Norte. Instituto de Investigación en Biodiversidad y Medioambiente; Argentin

Perspectivas de la comercializacion de la Lenga de Aysen.

110 p.La presente tesis da cuenta de la situación de la lenga de la XI Región, Aysén, particularmente sus posibilidades de comercialización en los mercados nacional e internacional. Mediante una encuesta practicada a los propios productores se obtuvo información inédita acerca de las características productivas de las empresas, relacionadas con el patrimonio, mecanización, capacidad de producción y enfoque productivo. Por otra parte, mediante la misma, se dan a conocer los aspectos comerciales vinculados a los canales de comercialización para los distintos tipos de productos. Corno consecuencia de la aplicación de la encuesta se pudo conocer la problemática real del desarrollo de la industria, sus ventajas y deficiencias. Finalmente se analiza el comportamiento histórico que ha tenido la lenga tanto en su aspecto comercial como productivo, a fin de orientar al lector hacia las perspectivas de comercialización de la especie