6,410 research outputs found
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
Feeling of grief and loss in parental caregivers of adults diagnosed with intellectual disability
Background: The diagnosis of intellectual disability in children can produce complex grief‐related feelings in their parents. Previous studies have focused on the moment of the diagnosis or the early life of the children, and little research has been conducted on their feelings of grief in adulthood. The objective was to analyse the process of grief/loss in parents of adult offspring with intellectual disability. Method: The intentional sampling included sixteen parents who responded to semi‐structured interviews. A qualitative study was conducted based on grounded theory. Results: Five categories were identified: “Reception of the diagnosis”, “Emotional bonds with the child”, “Experience of loss and feelings in response to intellectual disability diagnosis”, “Recurrent grief” and “Coping strategies”. Conclusions: Recurring feelings of loss experienced by parents in relation to their child's diagnosis persist over time. Specialized emotional interventions are needed to help parents to reduce the intensity of their feelings of grief
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