Bias corrections for probit and logit models with two-way fixed effects

In this article, we present the user-written commands probitfe and logitfe, which fit probit and logit panel-data models with individual and time unobserved effects. Fixed-effects panel-data methods that estimate the unobserved effects can be severely biased because of the incidental parameter problem (Neyman and Scott, 1948, Econometrica 16: –32). We tackle this problem using the analytical and jackknife bias corrections derived in Fernández-Val and Weidner (2016, Journal of Econometrics 192: 291–312) for panels where the two dimensions (N and T) are moderately large. We illustrate the commands with an empirical application to international trade and a Monte Carlo simulation calibrated to this application

First order transitions by conduction calorimetry: Application to deuterated potassium dihydrogen phosphate ferroelastic crystal under uniaxial pressure

The specific heat c and the heat power W exchanged by a Deuterated Potassium Dihydrogen Phosphate ferroelectric-ferroelastic crystal have been measured simultaneously for both decreasing and increasing temperature at a low constant rate (0.06 K/h) between 175 and 240 K. The measurements were carried out under controlled uniaxial stresses of 0.3 and 4.5±0.1 bar applied to face (110). At Tt=207.9 K, a first order transition is produced with anomalous specific heat behavior in the interval where the transition heat appears. This anomalous behavior is explained in terms of the temperature variation of the heat power during the transition. During cooling, the transition occurs with coexistence of phases, while during heating it seems that metastable states are reached. Excluding data affected by the transition heat, the specific heat behavior agrees with the predictions of a 2-4-6 Landau potential in the range of 4–15 K below Tt while logarithmic behavior is obtained in the range from Tt to 1 K below Tt. Data obtained under 0.3 and 4.5 bar uniaxial stresses exhibit the same behavior.Dirección General de Investigación Científica y Técnica. Gobierno de España-PB91-60

La Garza Real en España. I. Población reproductora (1950-2000)

En este trabajo se analiza la evolución de la población reproductora de Garza Real, Ardea cinerea, en España durante el período 1950-2000. El territorio español se ha dividido en siete grandes zonas: Norte, Levante, y las cuencas de los cinco grandes ríos (Guadalquivir, Guadiana, Tajo, Duero y Ebro). Los datos sobre colonias y número de parejas nidificantes fueron obtenidos a partir de prospecciones de los autores, de citas bibliográficas y de comunicaciones de organismos y personas conocedoras de las colonias. Es probable que ya antes de 1950 hubiera colonias ocupadas, pero se carece de datos publicados sobre ellas. En 1950 pudo haber 168 parejas reproductoras en 4 colonias, mientras que en 2000 hubo 4790 parejas en 75 colonias. Las subpoblaciones de garza real asentadas de las cuencas del Duero y Tajo parecen estar próximas al equilibrio numérico, mientras que las del Ebro, Guadalquivir y Levante han aumentado notablemente su tamaño en la década 1990-2000. La cuenca del Guadiana contenía relativamente pocas parejas en el período de estudio y en el Norte de España la población reproductora de la garza real es aún poco significativa

A Proposal for a Modified Moller-Plesset Perturbation Theory

A modified version of the Moller-Plesset approach for obtaining the correlation energy associated to a Hartree-Fock ground state is proposed. The method is tested in a model of interacting fermions that allows for an exact solution. Using up to third order terms improved results are obtained, even more accurate in the limit of loosely bound particles. This result suggests the possible convenience of the scheme for the study of chemical bound problems.Comment: 10 pages, 1 figur

Effectiveness of a program of romana’s Pilates for non-specific low back pain: A pilot study

Objetivo: comprobar la efectividad del método Pilates Romana para conseguir una mayor flexibilidad de la columna, junto con una mejora en la movilidad de la misma, así como del dolor que presentan en su vida diaria los pacientes. Metodología: ensayo clínico con intención de tratar a treinta pacientes con dolor lumbar inespecífico. Asistieron a 15 sesiones, 2 veces a la semana, del Método Pilates Romana.. Se evaluaron parámetros tales como dolor, test de Schöber, SRS-22 y distancia dedos- suelo. Resultados. Se encontraron diferencias estadísticamente significativas con respecto al dolor (escala EVA), distancia dedos- suelo, test de Schöber (flexibilidad en plano sagital), flexión lateral (flexibilidad en plano frontal) y en varios ítems de la escala SRS-22, con valores de p<0,001. Por ello, este método puede ser usado para mejorar el dolor, la flexibilidad axial, la función y los aspectos relacionados con la calidad de vidaAim: to test the effectiveness of the Romana’s Pilates method to obtain increased flexibility, improvements in mobility, and reduced pain in daily life. Methodology: a clinical trial with intention-to-treat thirty patients with nonspecific low back pain. Participants attended 15 sessions, twice a week. The Romana’s Pilates method was taught by an external physiotherapist. Parameters such as pain, the Schober test, and the SRS-22 were evaluated. Results: Statistically significant differences in pain (VAS), the Schober test (flexibility in sagittal plane), lateral flexion (flexibility in frontal plane) and several items of the SRS-22 scale were found, with p <0.001. This method may be used to improve pain, axial flexibility, function and aspects related to the quality of life of patient

Diagnosis of bronchial hyperresponsiveness in sport by PC20 value

En este trabajo se exponen los criterios de positividad del Comité Olímpico Internacional versus a la Sociedad Española de Neumología y Cirugía Torácica. Participaron en este estudio ochenta deportistas de alto rendimiento, realizando una historia clínica, una espirometría de reposo y un test de metacolina. Se analiza la sensibilidad y especificidad del test de metacolina mediante curvas ROC. El comité Internacional antidopaje (WADA) requiere que la disminución sea con un PC20 < a 4mg/ml, mientras que para la práctica clínica este descenso debe presentar un PC20 < 8mg/ml. Los resultados fueron: 25% tuvieron un PC20 > de 8mg/ml; el 61% obtuvieron un PC20 < 4mg/ml y un 14% presentaron un PC20 entre 4 y 8mg/ml, correspondiendo el mejor punto de corte a PC20 de 7,6mg/ml con especificidad de 98,3 y sensibilidad de 100%. Se tendría que determinar los mismos criterios para el diagnóstico de los deportistas y los que no lo son.In this work criteria of the International Olympic Committee versus the Spanish Society of Pneumology and Thoracic Surgery are exposed. A study was conducted in eighty high performance athletes of several sports . Who underwent a medical history, resting spirometry and a methacholine challenge test. You get the sensitivity and specificity of methacholine challenge test using Receiver Operating Curves (ROC curves). International anti-doping Committee requires that the decline is a PC20 < 4mg/ml, while clinical practice this fall must submit a PC20 < 8mg/ml. Twenty five percent of those studied had a PC20 > of 8mg/ml, 61% had a PC20 < 4mg/ml and 14% had a 4 to 8mg/ml PC20. The best cutoff point was found for a PC20 of 7.6 mg/ml with a specificity of 98.3 and a sensitivity of 100%. It would have to determine the same criteria for positive diagnosis of athletes and those who are not

Improved performance of LDPC-coded MIMO systems with EP-based soft-decisions

The proceeding at: IEEE International Symposium on Information Theory (ISIT 2014), took place 2014, June 29-July 04, in Honolulu (Hawai)Modern communications systems use efficient encoding schemes, multiple-input multiple-output (MIMO) and high-order QAM constellations for maximizing spectral efficiency. However, as the dimensions of the system grow, the design of efficient and low-complexity MIMO receivers possesses technical challenges. Symbol detection can no longer rely on conventional approaches for posterior probability computation due to complexity. Marginalization of this posterior to obtain per-antenna soft-bit probabilities to be fed to a channel decoder is computationally challenging when realistic signaling is used. In this work, we propose to use Expectation Propagation (EP) algorithm to provide an accurate low-complexity Gaussian approximation to the posterior, easily solving the posterior marginalization problem. EP soft-bit probabilities are used in an LDPC-coded MIMO system, achieving outstanding performance improvement compared to similar approaches in the literature for low-complexity LDPC MIMO decoding.This work has been partly funded by the Spanish Ministry of Science and Innovation with the projects GRE3NSYST (TEC2011-29006-C03-03) and ALCIT (TEC2012-38800-C03-01) and by the program CONSOLIDERINGENIO 2010 under the project COMONSENS (CSD 2008-00010).Publicad

A parallel algorithm for solving the incompressible Navier-Stokes problems

AbstractWe introduce and analyze a parallel algorithm for solving the Navier-Stokes equations based on the splitting of the two main difficulties involved, the presence of nonlinear terms and the zero divergence condition. The numerical results obtained by using the proposed algorithm are quite consistent with those furnished by other known algorithms. Numerical results are discussed, as well as the advantages of this new algorithm