bluuebunny/crossref_metadata_2025 huggingface dataset:
FUZZY LOGIC IN WEB DATA MINING FOR WEBSITE ASSESSMENT
Authors: LI XUE
Published: March 2003

This paper proposes a novel application of fuzzy logic to web data mining for two basic problems of a website: popularity and satisfaction. Popularity means that people will visit the website while satisfaction refers to the usefulness of the site. We will illustrate that the popularity of a website is a fuzzy logic problem. It is an important characteristic of a website in order to survive in Internet commerce. The satisfaction of a website is also a fuzzy logic problem that represents the degree of success in the application of information technology to the business. We propose a framework of fuzzy logic for the representation of these two problems based on web data mining techniques to fuzzify the attributes of a website.
AUTOMATIC FACIAL FEATURE EXTRACTION USING EDGE DISTRIBUTION AND GENETIC SEARCH
Authors: YEN GARY G. , NITHIANANDAN NETHRIE
Published: March 2003

A heuristic, automatic facial feature extraction approach is presented in this paper. The method is based on the edge density distribution of the image, containing non-occluded, nearly frontal view of one or more faces. In the preprocessing stage, a face is approximated to an ellipse, and genetic algorithm is applied to search for the best ellipse region match. In the feature extraction stage, genetic algorithm is applied to extract the facial features, such as the eyes (with eyebrows), nose and mouth, in the predefined subregions. The simulation results validates that the proposed method is capable of automatically extracting features from various video images effectively under natural lighting environments and in the presence of complex backgrounds, certain amount of artificial noise and of multi-face oriented with angles. This preliminary study advanced from a rich literature provides robust facial feature detection under certain variations in lighting conditions and backgrounds.
Epicardial/Mesothelial Cell Line Retains Vasculogenic Potential of Embryonic Epicardium
Authors: Wada Aya M. , Smith Travis K. , Osler Megan E. , Reese David E. , Bader David M.
Published: March 2003

Recent work has demonstrated the importance of the epicardium in the development of the heart. During embryogenesis, these epithelial cells provide the progenitors for the epicardium, coronary smooth muscle, endothelium, and cardiac fibroblasts. The epicardium sends important signals to the developing myocardium. Still, analysis of these epithelial cells has lagged behind that of other cardiac cell types largely because of the lack of a defined experimental cell system in which epicardial cell differentiation can be studied. The present report examines the developmental potential of a cell line derived from rat epicardial mesothelial cells. These analyses demonstrate that the cell line retains many characteristics of the intact epithelium, including the ability to form a polarized epithelium and express many epicardial genes. Our data show for the first time that these cells retain the ability to produce mesenchyme in response to specific growth factors and, importantly, to generate smooth muscle cells. Thus, this study provides evidence that these cells can serve as an important model system for the analysis of the cellular and molecular mechanisms that govern epicardial development and function.
Peroxisome Proliferator-Activated Receptor (PPAR) α and PPARβ/δ, but not PPARγ, Modulate the Expression of Genes Involved in Cardiac Lipid Metabolism
Authors: Gilde Andries J. , van der Lee Karin A.J.M. , Willemsen Peter H.M. , Chinetti Giulia , van der Leij Feike R. , van der Vusse Ger J. , Staels Bart , van Bilsen Marc
Published: March 2003

Long-chain fatty acids (FA) coordinately induce the expression of a panel of genes involved in cellular FA metabolism in cardiac muscle cells, thereby promoting their own metabolism. These effects are likely to be mediated by peroxisome proliferator-activated receptors (PPARs). Whereas the significance of PPARα in FA-mediated expression has been demonstrated, the role of the PPARβ/δ and PPARγ isoforms in cardiac lipid metabolism is unknown. To explore the involvement of each of the PPAR isoforms, neonatal rat cardiomyocytes were exposed to FA or to ligands specific for either PPARα (Wy-14,643), PPARβ/δ (L-165041, GW501516), or PPARγ (ciglitazone and rosiglitazone). Their effect on FA oxidation rate, expression of metabolic genes, and muscle-type carnitine palmitoyltransferase-1 (MCPT-1) promoter activity was determined. Consistent with the PPAR isoform expression pattern, the FA oxidation rate increased in cardiomyocytes exposed to PPARα and PPARβ/δ ligands, but not to PPARγ ligands. Likewise, the FA-mediated expression of FA-handling proteins was mimicked by PPARα and PPARβ/δ, but not by PPARγ ligands. As expected, in embryonic rat heart-derived H9c2 cells, which only express PPARβ/δ, the FA-induced expression of genes was mimicked by the PPARβ/δ ligand only, indicating that FA also act as ligands for the PPARβ/δ isoform. In cardiomyocytes, MCPT-1 promoter activity was unresponsive to PPARγ ligands. However, addition of PPARα and PPARβ/δ ligands dose-dependently induced promoter activity. Collectively, the present findings demonstrate that, next to PPARα, PPARβ/δ, but not PPARγ, plays a prominent role in the regulation of cardiac lipid metabolism, thereby warranting further research into the role of PPARβ/δ in cardiac disease.
Modeling Reverse-Phi Motion-Selective Neurons in Cortex: Double Synaptic-Veto Mechanism
Authors: Mo Chun-Hui , Koch Christof
Published: March 2003

Reverse-phi motion is the illusory reversal of perceived direction of movement when the stimulus contrast is reversed in successive frames. Livingstone, Tsao, and Conway (2000) showed that direction-selective cells in striate cortex of the alert macaque monkey showed reversed excitatory and inhibitory regions when two different contrast bars were flashed sequentially during a two-bar interaction analysis. While correlation or motion energy models predict the reverse-phi response, it is unclear how neurons can accomplish this. We carried out detailed biophysical simulations of a direction-selective cell model implementing a synaptic shunting scheme. Our results suggest that a simple synaptic-veto mechanism with strong direction selectivity for normal motion cannot account for the observed reverse-phi motion effect. Given the nature of reverse-phi motion, a direct interaction between the ON and OFF pathway, missing in the original shunting-inhibition model, it is essential to account for the reversal of response. We here propose a double synaptic-veto mechanism in which ON excitatory synapses are gated by both delayed ON inhibition at their null side and delayed OFF inhibition at their preferred side. The converse applies to OFF excitatory synapses. Mapping this scheme onto the dendrites of a direction-selective neuron permits the model to respond best to normal motion in its preferred direction and to reverse-phi motion in its null direction. Two-bar interaction maps showed reversed excitation and inhibition regions when two different contrast bars are presented.
Visual Development and the Acquisition of Motion Velocity Sensitivities
Authors: Jacobs Robert A. , Dominguez Melissa
Published: March 2003

We consider the hypothesis that systems learning aspects of visual perception may benefit from the use of suitably designed developmental progressions during training. Four models were trained to estimate motion velocities in sequences of visual images. Three of the models were developmental models in the sense that the nature of their visual input changed during the course of training. These models received a relatively impoverished visual input early in training, and the quality of this input improved as training progressed. One model used a coarse-to-multiscale developmental progression (it received coarse-scale motion features early in training and finer-scale features were added to its input as training progressed), another model used a fine-to-multiscale progression, and the third model used a random progression. The final model was nondevelopmental in the sense that the nature of its input remained the same throughout the training period. The simulation results show that the coarse-to-multiscale model performed best. Hypotheses are offered to account for this model's superior performance, and simulation results evaluating these hypotheses are reported. We conclude that suitably designed developmental sequences can be useful to systems learning to estimate motion velocities. The idea that visual development can aid visual learning is a viable hypothesis in need of further study.
Modeling Cross-Modal Enhancement and Modality-Specific Suppression in Multisensory Neurons
Authors: Patton Paul E. , Anastasio Thomas J.
Published: March 2003

Cross-modal enhancement (CME) occurs when the neural response to a stimulus of one modality is augmented by another stimulus of a different modality. Paired stimuli of the same modality never produce supra-additive enhancement but may produce modality-specific suppression (MSS), in which the response to a stimulus of one modality is diminished by another stimulus of the same modality. Both CME and MSS have been described for neurons in the deep layers of the superior colliculus (DSC), but their neural mechanisms remain unknown. Previous investigators have suggested that CME involves a multiplicative amplifier, perhaps mediated by N-methyl D-aspartate (NMDA) receptors, which is engaged by cross-modal but not modality-specific input. We previously postulated that DSC neurons use multisensory input to compute the posterior probability of a target using Bayes' rule. The Bayes' rule model reproduces the major features of CME. Here we use simple neural implementations of our model to simulate both CME and MSS and to argue that multiplicative processes are not needed for CME, but may be needed to represent input variance and covariance. Producing CME requires only weighted summation of inputs and the threshold and saturation properties of simple models of biological neurons. Multiplicative nodes allow accurate computation of posterior target probabilities when the spontaneous and driven inputs have unequal variances and covariances. Neural implementations of the Bayes' rule model account better than the multiplicative amplifier hypothesis for the effects of pharmacological blockade of NMDA receptors on the multisensory responses of DSC neurons. The neural implementations also account for MSS, given only the added hypothesis that input channels of the same modality have more spontaneous covariance than those of different modalities.
Event-Driven Simulation of Spiking Neurons with Stochastic Dynamics
Authors: Reutimann Jan , Giugliano Michele , Fusi Stefano
Published: March 2003

We present a new technique, based on a proposed event-based strategy (Mattia & Del Giudice, 2000), for efficiently simulating large networks of simple model neurons. The strategy was based on the fact that interactions among neurons occur by means of events that are well localized in time (the action potentials) and relatively rare. In the interval between two of these events, the state variables associated with a model neuron or a synapse evolved deterministically and in a predictable way. Here, we extend the event-driven simulation strategy to the case in which the dynamics of the state variables in the inter-event intervals are stochastic. This extension captures both the situation in which the simulated neurons are inherently noisy and the case in which they are embedded in a very large network and receive a huge number of random synaptic inputs. We show how to effectively include the impact of large background populations into neuronal dynamics by means of the numerical evaluation of the statistical properties of single-model neurons under random current injection. The new simulation strategy allows the study of networks of interacting neurons with an arbitrary number of external afferents and inherent stochastic dynamics.
Isotropic Sequence Order Learning
Authors: Porr Bernd , Wörgötter Florentin
Published: March 2003

In this article, we present an isotropic unsupervised algorithm for temporal sequence learning. No special reward signal is used such that all inputs are completely isotropic. All input signals are bandpass filtered before converging onto a linear output neuron. All synaptic weights change according to the correlation of bandpass-filtered inputs with the derivative of the output. We investigate the algorithm in an open- and a closed-loop condition, the latter being defined by embedding the learning system into a behavioral feedback loop. In the open-loop condition, we find that the linear structure of the algorithm allows analytically calculating the shape of the weight change, which is strictly heterosynaptic and follows the shape of the weight change curves found in spike-time-dependent plasticity. Furthermore, we show that synaptic weights stabilize automatically when no more temporal differences exist between the inputs without additional normalizing measures. In the second part of this study, the algorithm is is placed in an environment that leads to closed sensor-motor loop. To this end, a robot is programmed with a prewired retraction reflex reaction in response to collisions. Through isotropic sequence order (ISO) learning, the robot achieves collision avoidance by learning the correlation between his early range-finder signals and the later occurring collision signal. Synaptic weights stabilize at the end of learning as theoretically predicted. Finally, we discuss the relation of ISO learning with other drive reinforcement models and with the commonly used temporal difference learning algorithm. This study is followed up by a mathematical analysis of the closed-loop situation in the companion article in this issue, “ISO Learning Approximates a Solution to the Inverse-Controller Problem in an Unsupervised Behavioral Paradigm” (pp. 865–884).
ISO Learning Approximates a Solution to the Inverse-Controller Problem in an Unsupervised Behavioral Paradigm
Authors: Porr Bernd , Ferber Christian von , Wörgötter Florentin
Published: March 2003

In “Isotropic Sequence Order Learning” (pp. 831–864 in this issue), we introduced a novel algorithm for temporal sequence learning (ISO learning). Here, we embed this algorithm into a formal nonevaluating (teacher free) environment, which establishes a sensor-motor feedback. The system is initially guided by a fixed reflex reaction, which has the objective disadvantage that it can react only after a disturbance has occurred. ISO learning eliminates this disadvantage by replacing the reflex-loop reactions with earlier anticipatory actions. In this article, we analytically demonstrate that this process can be understood in terms of control theory, showing that the system learns the inverse controller of its own reflex. Thereby, this system is able to learn a simple form of feedforward motor control.
Localization of Function via Lesion Analysis
Authors: Aharonov Ranit , Segev Lior , Meilijson Isaac , Ruppin Eytan
Published: March 2003

This article presents a general approach for employing lesion analysis to address the fundamental challenge of localizing functions in a neural system. We describe functional contribution analysis (FCA), which assigns contribution values to the elements of the network such that the ability to predict the network's performance in response to multilesions is maximized. The approach is thoroughly examined on neurocontroller networks of evolved autonomous agents. The FCA portrays a stable set of neuronal contributions and accurate multilesion predictions that are significantly better than those obtained based on the classical single lesion approach. It is also used for a detailed synaptic analysis of the neurocontroller connectivity network, delineating its main functional backbone. The FCA provides a quantitative way of measuring how the network functions are localized and distributed among its elements. Our results question the adequacy of the classical single lesion analysis traditionally used in neuroscience and show that using lesioning experiments to decipher even simple neuronal systems requires a more rigorous multilesion analysis.
The Concave-Convex Procedure
Authors: Yuille A. L. , Rangarajan Anand
Published: March 2003

The concave-convex procedure (CCCP) is a way to construct discrete-time iterative dynamical systems that are guaranteed to decrease global optimization and energy functions monotonically. This procedure can be applied to almost any optimization problem, and many existing algorithms can be interpreted in terms of it. In particular, we prove that all expectation-maximization algorithms and classes of Legendre minimization and variational bounding algorithms can be reexpressed in terms of CCCP. We show that many existing neural network and mean-field theory algorithms are also examples of CCCP. The generalized iterative scaling algorithm and Sinkhorn's algorithm can also be expressed as CCCP by changing variables. CCCP can be used both as a new way to understand, and prove the convergence of, existing optimization algorithms and as a procedure for generating new algorithms.
An Analysis of Synaptic Normalization in a General Class of Hebbian Models
Authors: Elliott Terry
Published: March 2003

In standard Hebbian models of developmental synaptic plasticity, synaptic normalization must be introduced in order to constrain synaptic growth and ensure the presence of activity-dependent, competitive dynamics. In such models, multiplicative normalization cannot segregate afferents whose patterns of electrical activity are positively correlated, while subtractive normalization can. It is now widely believed that multiplicative normalization cannot segregate positively correlated afferents in any Hebbian model. However, we recently provided a counterexample to this belief by demonstrating that our own neurotrophic model of synaptic plasticity, which can segregate positively correlated afferents, can be reformulated as a nonlinear Hebbian model with competition implemented through multiplicative normalization. We now perform an analysis of a general class of Hebbian models under general forms of synaptic normalization. In particular, we extract conditions on the forms of these rules that guarantee that such models possess a fixed-point structure permitting the segregation of all but perfectly correlated afferents. We find that the failure of multiplicative normalization to segregate positively correlated afferents in a standard Hebbian model is quite atypical.
RECONSTRUCTING THE WORLD OF ANCIENT MESOPOTAMIA: DIVIDED BEGINNINGS AND HOLISTIC HISTORY
Authors: Zettler Richard
Published: March 2003

Since its inception in the nineteenth century, ancient Mesopotamian studies has recognized a division of labor between archaeologists and philologists/historians that has often skewed histories of the "land between the rivers." Recent efforts, inspired in part by the Sumerologist Thorkild Jacobsen, offer hope for more holistic histories. Three case studies—on the Inanna temple at Nippur under the Third Dynasty of Ur, abrupt climate change in the late third millennium and its social impact as reconstructed from environmental proxy data and textual sources, and the Sumerian Agriculture Group's collaborative research on subsistence—typify efforts to integrate material culture and texts. Dès le début des études sur la Mésopotamie ancienne au 19ème siècle, un fossé s'est creusé entre les archéologues et les philologues/historiens, et les travaux historiques portant sur le "pays entre les fleuves" en ont souvent été influencés. De récents efforts, inspirés en partie par le sumérologue Thorkild Jacobsen, permettent d'espérer une histoire plus compréhensive. Trois études de cas caractérisent les efforts d'intégration des données de la culture matérielle et des documents écrits: le temple d'Inanna à Nippour sous la troisième dynastie d'Ur; le brusque changement de climat survenu vers la fin du troisième millénaire et son impact social reconstruits à partir de textes et de données indirectes dérivées de l'environnement; enfin la recherche en interdisciplinaire du Sumerian Agriculture Group sur les ressources alimentaires.
BERENIKE CROSSROADS: THE INTEGRATION OF INFORMATION
Authors:   Tomber,   Wendrich,   Harrell,   Sidebotham,   Bagnall,   Cappers
Published: March 2003

The harbor town of Berenike functioned in the long-distance trade between the Mediterranean and the Indian Ocean Basin from the third century BC to the early sixth century AD. This contribution aims to view the Berenike material within its wider historical context through a preliminary analysis of the combined archaeological and textual evidence. By comparing the results of the work of different specialists, the potential of a multi-disciplinary approach becomes apparent. A number of caveats are given, which illustrate the interpretative problems arising from comparing the results of different disciplines. Lastly, this attempt at integration shows that the discrepancies between the different sources offer important insights. Le port maritime de Berenike fonctionnait dans le commerce de longue distance entre la Méditerranée et le bassin de la Mer des Indes depuis le troisième siècle avant JC jusqu'au début du sixième siècle après JC. Cette contribution examine le matériel de Berenike dans un contexte plus large par une analyse préliminaire croisant des données archéologiques et textuelles. En comparant les résultats proposés par plusieurs spécialistes, le potentiel du travail multidisciplinaire devient évident. Un nombre de caveats est présenté pour illustrer des problèmes d'interprétation, provenant des comparaisons de résultats de plusieurs disciplines. Enfin, cet essai d'intégration montre que les divergences entre plusieurs sources offre des aperçus importants.
JI'NAN IN THE FIRST MILLENNIUM B.C.: ARCHAEOLOGY AND HISTORY
Authors:   Min
Published: March 2003

Interpretations derived from the study of texts have often determined how material remains have been explained in the historical archaeology of ancient China. Thus, the history of China has been less informed by archaeological knowledge than one would wish. In the case of social transitions in the Ji'nan region in the first millennium B.C., I show how changes in settlement patterns and in mortuary practices enrich our understanding of how the increasingly centralized state impacted the local Ji'nan society. Les interprétations provenant de l'étude des textes ont souvent déterminé la manière dont les vestiges matériels ont été intégrés dans l'archéologie historique de la Chine Ancienne. Pour cette raison, l'apport des données archéologiques sur la connaissance de la Chine. Ancienne est bien moindre qu1on ne le pense. Dans le cas des transitions sociales dans la région de Ji1nan au cours du 1er Millénaire B.C., cet article montre comment les changements intervenus dans la distribution régionale des sites et dans les pratiques funéraires enrichit notre perception des effets de l'action de l'état centralisateur sur la société locale du Ji'nan.
Aproximación naturalista a la conducta social infantil: el intercambio de recursos en preescolares
Authors: Gaviria Elena
Published: March 2003

El intercambio de recursos ha sido estudiado por los psicólogos sociales casi exclusivamente mediante una metodología experimental y siguiendo un paradigma inspirado en contextos laborales. En los trabajos con sujetos infantiles los resultados indican que los intercambios no siguen más regla que el propio interés o, como mucho, la igualdad antes de los 7 años. El objetivo de este estudio era abordar el intercambio de una manera más naturalista, en busca de criterios más relevantes para preescolares que los utilizados en los experimentos. Empleando una metodología observacional y un planteamiento conceptual basados en gran parte en la investigación etológica, se estudió a dos grupos de niños en periodos de juego libre en guarderías, categorizando su conducta y sus interacciones apelando a la dominancia social y la donación-recepción de recursos. Los resultados indican que la conducta social de los preescolares es bastante más compleja y sofisticada de lo que reflejan los estudios experimentales, y sugieren la necesidad de un planteamiento más inductivo antes de entrar en el laboratorio, especialmente cuando se trata de sujetos infantiles.
Contrastación experimental de las teorías del drive o impulso de la facilitación social
Authors: Delgado Tomás Gómez , Rubio José María León
Published: March 2003

En las últimas tres décadas la Facilitación Social ha llevado a los investigadores al desarrollo de un buen número de diferentes teorías que han tratado de dar cuenta del fenómeno psicosocial más básico. A pesar de esta prolijidad teórica carecemos de una explicación satisfactoria de éste. Además, el contraste experimental de las diferentes hipótesis, que sería enormemente clarificador, no ha sido nunca llevado a efecto. Por consiguiente el objetivo principal de este trabajo ha sido diseñar una situación experimental adecuada que intetará clarificar los graves problemas teóricos y metodológicos que rodean a la Facilitación Social. Utilizando un diseño experimental mixto (6×2) pudimos contrastar simultáneamente las principales teorías sobre la Facilitación Social (hipótesis del drive). En relación con los mencionados problemas teóricos y metodológicos, fue necesario una definición rigurosa del arousal (como un patrón multidimensional integrado de diferentes parámetros psicofisiológicos) y de los grupos control (con sujetos realmente solos). Tras este esfuerzo de reconceptualización los resultados mostraron que sólo en el grupo «mera presencia I» se obtuvieron claros efectos de Facilitación Social (F(5, 78)= 3.5, p=.01; t.005, 13 =3.33) y cambios significativos en sus patrones psicofisiológicos (t.000; t. 005; t.05; t.03). Esto implica que el punto de vista más parsimonioso (nuestra redefinición de la hipótesis de la mera presencia de ZAJONC, 1965, 1980) es el único que debe ser utilizado para la explicación del fenómeno. En otras palabras, ahora estamos en condiciones de empezar a vislumbrar una teoría integrada de la Facilitación Social basada en la perspectiva sistémica que aporta la Psicofisiología Social y con una concepción multidimensional como mediador básico del proceso.
¿Somos sinceros al comunicar nuestras emociones a los demás? El caso de los celos y la tristeza
Authors: Levillain Pilar Carrera , Zammuner Vanda L. , Colodrón María
Published: March 2003

Cuando hablamos sobre nuestras emociones con los demás no siempre somos sinceros. En este estudio, las diferencias entre la experiencia emocional y lo que se comunicaría sobre ella, se pusieron de manifiesto cualitativa y cuantitativamente. Estas diferencias, entre lo sentido) y lo comunicado, fueron mayores en las situaciones de celos que en las de tristeza. Dos muestras españolas de varones y mujeres confirmaron estas discrepancias, apuntadas en trabajos previos con muestras italianas (Zammuner y Frijda, 1994). En esta ausencia de sinceridad tuvo una influencia relevante la categoría emocional implicada, el nivel de gravedad o importancia de las situaciones antecedentes (grave vs. leve) y el grado de intimidad mantenido con el interlocutor (pareja vs. conocidola), aunque eneste último factor sólo de forma tendencial. Estos resultados confirman la existencia de pautas de regulación en la comunicación verbal de las emociones.
Variables que contribuyen a fumar tabaco entre una muestra joven: un análisis multivariable
Authors: Rooney James F. , González Jesús Villahoz
Published: March 2003

Al estudiar la incidencia del consumo de cigarrillos entre la población estudiantil (10–18 años) y su relación con las variables más significativas, nos encontramos con la compleja realidad que sufre modificaciones en estas edades. De ahí que las variables significativas sufran numerosos cambios, por ej. el número de amigos que fuman según los diferentes grupos de edad. A los 10–11 años, el hecho de fumar más, se relaciona con el número de horas de estudio en casa y con la menor estimación de peligro que supone para la salud. A los 12–13 años será la propia actitud del alumno hacia el fumar, y a partir de los 14–15 años será tanto la actitud del grupo de amigos como la sensación de la identidad personal. Por otro lado, se resalta el importante factor de cambio que supone pasar de E.G.B. a EE.MM.
El papel del apoyo social en la experiencia de dolor crónico. Un estudio empírico
Authors: de los Angeles Pastor María , López-Roig Sofía , Rodríguez-Marín Jesús , Salas Esteban , Sánchez Salvador , del Carmen Terol María
Published: March 2003

Este trabajo tiene como objetivos, en primer lugar, comparar la percepción de, y satisfacción con, el apoyo social ofrecido por la red familiar y por la general o difusa en un grupo de enfermos con dolor crónico sin patología orgánica (fibromialgia: n=49) y en otros dos grupos de enfermos reumáticos (artritis reumatoidea: n=35 y artrosis: n=35). En segundo lugar, comparar en los mismos grupos su percepción de las respuestas recibidas desde el medio familiar a la comunicación de dolor. En tercer lugar, analizar la capacidad predictiva de las variables de apoyo social en el impacto de la fibromialgia, y compararla con su capacidad predictiva en el resto de enfermedades estudiadas.

Los resultados muestran que la existencia o no de etiología para el dolor crónico reumático, no es una cuestión determinante en la percepción de apoyo social. Además, el papel de las variables mencionadas en la experiencia de dolor crónico varía en función de la enfermedad y de la variable resultado que se considere (distrés, dolor o discapacidad).
Estrés, apoyo social y ajuste psicológico en padres que maltratan a sus hijos
Authors: Fuster Enrique Gracia , Ochoa Gonzalo Musitu , Pérez Fernando García
Published: March 2003

Los objetivos de este estudio son: a) examinar los niveles de estrés, ajuste psicológico y apoyo social comunitario en padres que maltratan a sus hijos, y b) el rol potencial del apoyo social como variable moduladora en las relaciones entre estrés y ajuste psicológico en familias con problemas de maltrato infantil. El nivel global de estrés experienciado por los padres, así como los sucesos y cambios vitales en la unidad familiar fueron evaluados a partir del FILE (McCubbin y cols.), el índice de ajuste psicológico se obtuvo a partir del SCL-90 (Derogatis y cols.) y, finalmente, el apoyo social comunitario fue evaluado mediante el AC-90 (Gracia y Musitu). La muestra se compone de 150 padres normales y 60 con problemas de maltrato. Los resultados obtenidos permiten concluir que los padres que maltratan a sus hijos experimentan niveles más elevados de estrés, presentan índices de sintomatología psicopatológica más elevados y se encuentran más aislados socialmente. El examen de las relaciones entre las variables analizadas revela una relación positiva directa entre el nivel de estrés y el ajuste psicológico, independientemente del nivel de apoyo social. No se han obtenido, sin embargo, efectos directos del apoyo social en la variable sintomatología, ni nuestros resultados permiten inferir un efecto modulador o protector («buffer») del apoyo social comunitario frente al impacto negativo de los estresores en el ajuste psicológico
Efectos culturales de las normas perversas
Authors: Fernández-Dols José Miguel , Amate Mar , Caballero Amparo , Ruiz-Belda María Angeles , Sell Lucía , Oceja Luis
Published: March 2003

Según el concepto de «norma perversa» (Fernández-Dols, 1993), la importancia de los amigos y los conocidos en la sociedad española no es debida a un mayor colectivismo sino a graves disfunciones en las organizaciones burocráticas que impulsan a buscar conocidos cuando debemos gestionar una cuestión formal pero no en contextos informales. El presente estudio trató de comprobar esta hipótesis comparando el grado en que sujetos españoles y británicos percibían que era necesario el recurso a conocidos en contextos burocráticos y contextos informales. De acuerdo con la predicción, los conocidos son tan importantes o incluso más importantes para los británicos en contextos informales pero los españoles valoran de forma significativamente más alta a los conocidos para la gestión de asuntos burocráticos.
Procesos culturales e individuales implicados en la estereotipia de genero. Una aproximación empírica a la elección de carrera
Authors: López-Sáez Mercedes
Published: March 2003

Se revisan los trabajos empíricos más importantes sobre estereotipia de género (Rosenkrantz, Broverman, Spence, Williams y Best, Bem, Markus, Deaux). Un análisis detallado de ellos lleva a la conclusión de la importancia de considerar el género como un constructo cultural, compuesto por el conjunto de creencias sobre las características que diferencialmente se asignan a hombres y mujeres.

Se presenta un estudio empírico, en el que se analizan las diferencias en elección de carrera entre hombres y mujeres. Este problema se aborda desde un enfoque psicosocial, en el que se tiene en cuenta la interacción entre el sexo (como categoría social a la que se pertenece) y el género (como conjunto de creencias asociadas a esas categorías). Los resultados obtenidos en una muestra de chicos y chicas estudiantes de Ingeniería Industrial (N = 100) y de chicos y chicas estudiantes de Pedagogía (N = 86) ponen de manifiesto la importancia del género para discriminar entre las personas que eligen una carrera «típicamente» femenina o masculina.
La evaluación del personal profesional: ¿un modelo de evaluación nuevo o una síntesis de modelos previos?
Authors: Pacheco Enrique Rebolloso
Published: March 2003

En consonancia con la aspiración de mejorar la calidad de los servicios institucionales de la Administración Pública, presentamos un modelo de «evaluación participativa» que incluye la «negociación» como uno de sus elementos claves. Dicho modelo está intencionalmente dirigido a la provisión de información para el perfeccionamiento y mejora de los servicios profesionales de la Universidad, así como a la validación de los principios que deberían regir el modelo mismo de evaluación que propugnamos. La posición que adelantamos aquí sostiene que en la realidad del trabajo aplicado hay diferentes tipos de evaluación y que en el presente estado de desarrollo teórico en que nos encontramos sería mejor describirlos y aplicarlos que intentar establecer una gran teoría de la evaluación. Nuestra principal finalidad es, pues, dar a conocer y fomentar el uso de un cuerpo coherente e integrado de estrategias de evaluación de ninguna manera consideradas exhaustivas de todas las posibilidades reales o potenciales. La conceptualización contempla a la investigación de evaluación como la acción culminante del «estado del arte» de la disciplina interesada en la provisión y difusión del conocimiento necesario para fortalecer las acciones instrumentales que elevan los standards de rendimiento, destreza y motivación del personal profesional que vaya a ser objeto de evaluación. Los fundamentos descansan, por una parte, en principios unánimamente aceptados por la comunidad evaluativa y, de otra parte, en la práctica desarrollada por el autor a través de la ejecución de proyectos de corte parecido que conciben el concepto de evaluación como algo más que la simple idea de medida, descripción y juicio.
Increased levels of protein kinase C in lymphocytes in asthma: possible mechanism of regulation
Authors: Bansal SK , Jha A , Jaiswal AS , Chhabra SK
Published: March 2003

Asthma is an inflammatory disease of the airways. Activation of lymphocytes leads to elaboration of inflammatory mediators which are likely to initiate and perpetuate the asthmatic response. During activation of lymphocytes, the role of protein kinase C (PKC) has been emphasized. Therefore, changes in PKC activity in peripheral blood lymphocytes in bronchial asthma can be expected, which may be due to alterations in the regulatory mechanisms of the enzyme molecule. To understand the mechanism of regulation of PKC activity the effects of drugs, such as carbachol, histamine, sphingosine and disodium cromoglycate (DSCG), on the lymphocytes of healthy subjects were studied. The study included 27 asthmatic patients and 14 healthy volunteers. Disease was classified as mild, moderate-to-severe, and cases in remission. PKC activity was determined in peripheral blood lymphocytes by [3H] phorbol 12,13-dibutyrate ([3H]PDBu)-binding assay. A highly significant (p < 0.001) increase was observed in total, cytosolic and membrane PKC activity in all of the asthmatic patients as compared to the healthy group. There was an increased translocation of PKC from cytosol to membrane in all of the groups, and the extent of translocation of the enzyme indicates physiological activation of the cells. A highly significant (p < 0.001) reciprocal relationship (r = -0.47) existed between forced expiratory volume in one second (FEV1) as percentage predicted and total PKC activity in bronchial asthma. Carbachol and histamine significantly (p < 0.001) increased PKC activity in lymphocytes, the increase being dose-dependent for histamine. Sphingosine or disodium cromoglycate (DSCG) brought about complete inhibition of PKC activity at 100 nM. We conclude that protein kinase C activity is increased in lymphocytes in bronchial asthma. Our findings suggest that the mediators (carbachol and histamine), and drugs (sphingosine and disodium cromoglycate) possibly exert their action on protein kinase C by influencing the regulatory domain of the enzyme.
Effect of transmural pressure on preloads and collapse of immature bronchi
Authors: McFawn PK , Mitchell HW
Published: March 2003

Immature airways are highly compliant compared to the adult, suggesting that trachea and bronchi from immature animals may be easily compressed. Although tracheal compression has been extensively studied, the effect of transmural pressure on occlusion of immature bronchi has been neglected. The transmural pressure at which the lumen closed was determined from the transmittance of pressure along the lumen of isolated bronchi from late-term foetal, 1 and 4 week old pigs. Bronchi from eight cases of sudden infant death syndrome (SIDS) were also studied. In several experiments, smooth muscle tone was produced either by electrical field stimulation or carbachol challenge, and the relationship between active muscle tone and resting transmural pressure was studied. Bronchi from foetal, 1 and 4 week old pigs were occluded by intraluminal pressures of -4, -5 and -24 cmH2O. SIDS bronchi closed at -11 cmH2O. Histological and endoscopic investigations showed that closure of the bronchi occurred along a plane and was not uniform along the bronchus. Carbachol precontraction increased the transmural pressure required to close bronchi by approximately 5 cmH2O. The relationship between muscle tone and resting pressure was the same in all age groups, except when transmural pressure was at or below closing pressure. Bronchi from immature animals and human infants are vulnerable to collapse by small changes in transmural pressure. Bronchial closure is partly dependent on smooth muscle tone, particularly in younger animals.
Factors relating to the severity of symptoms at 5 yrs in children with severe wheeze in the first 2 yrs of life
Authors: Wilson NM , Dore CJ , Silverman M
Published: March 2003

Wheezing in early childhood covers a wide spectrum of morbidity. Since little is known about the factors determining either the pattern or the severity of this range of symptoms, 51 children, admitted to hospital with acute wheeze in the first 2 yrs of life, were monitored prospectively between the ages of 4.5-5.5 yrs. Our hypothesis was that the predictors of severe episodes and of interval symptoms in 5 year olds would differ. Symptom diaries were kept, from which the symptom pattern and severity was assessed. The frequency and severity of acute episodes were analysed separately from day-to-day (interval) symptoms. A physiological assessment was made at 5 yrs. During the 12 month study period, 11 children were symptom-free, 15 were reported to wheeze only in response to viral infections, and 25 wheezed from multiple triggers. Bronchial responsiveness was significantly increased in those with a family history of asthma but was unrelated to any index of atopy. In a multiple logistic regression analysis, a family history of asthma and a personal history of allergy (but not results of skin-prick testing or serum immunoglobulin E (IgE) significantly predicted both attack severity and interval symptoms. An additive effect of two factors (atopy plus a family history of asthma or bronchial responsiveness) on symptom severity was suggested, without any evidence of an interaction. It is concluded that in this population of 5 year olds, with an early history of severe wheezing, familial bronchial responsiveness and atopy of operated independently to determine both interval symptoms and attack severity.
Effect of a bed covering system in children with asthma and house dust mite hypersensitivity
Authors: Frederick JM , Warner JO , Jessop WJ , Enander I , Warner JA
Published: March 2003

Allergen avoidance is regarded as an important approach to management of atopic asthma. The effect of Intervent bed covering systems on house dust mite (HDM) allergen exposure, asthma symptoms and markers of inflammation was investigated in 31 HDM sensitive asthmatic children. Dust concentrations of Dermatophagoides pteronyssinus allergen 1 (Der p 1) were monitored before and after covering the mattress, duvet and pillow with active and placebo covers for 3 months, in a single-blind, cross-over trial. Twice daily peak expiratory flow rate (PEFR), daily symptom scores and treatment schedule were recorded. Bronchial hyperresponsiveness was monitored by histamine challenge (provocative concentration of histamine causing a 20% fall in forced expiratory volume in one second (PC20)), and inflammation by measuring eosinophil cationic protein (ECP), eosinophil protein X (EPX), eosinophil peroxidase (EPO), and soluble interleukin-2 receptor (sIL-2R) in serum. There was a significant reduction in Der p 1 when the mattress, duvet and pillow were covered with the active bedding. There was no significant improvement in symptoms of asthma, PEFR, bronchodilator usage of PC20. Also, ECP, EPX, sIL-2R concentrations did not change for either treatment. EPO concentrations were significantly lower in the active compared to the placebo period. The active bed covers reduced retrievable Dermatophagoides pteronyssinus allergen 1 (Der p 1) from the bedding, with short term clinical benefit.
Upper airway obstruction and raised intracranial pressure in children with craniosynostosis
Authors: Gonsalez S , Hayward R , Jones B , Lane R
Published: March 2003

In children with craniosynostosis, raised intracranial pressure (ICP) and upper airway obstruction (UAO) are both common features. However, potential interactions between UAO and ICP during sleep are poorly understood. The aim of the present study was to compare the levels of ICP during sleep between a group of patients with syndromic craniosynostosis (with facial involvement and consequent UAO) and a group of control patients with isolated unicoronal synostosis (with no facial involvement and normal upper airways). Polygraphic cardiorespiratory sleep studies with continuous monitoring of ICP were performed during unsedated sleep in 13 children with syndromic craniosynostosis and 7 control patients with isolated unicoronal synostosis only. In the syndromic group, UAO was present in 11 out of 13 patients, with 8 out of 13 having frank obstructive sleep apnoea. In contrast, none of the control patients showed signs of UAO during sleep. There was no evidence of central apnoeas in any of the patients studied. Clinical histories taken from parents tended to underestimate the severity of the respiratory problems. Elevated ICP was seen in 10 of the 13 syndromic patients, with borderline raised ICP in the remaining three cases. In contrast, raised ICP was seen in only 3 of the 7 control patients, with borderline raised levels in 2 of the 7. For both patient groups, ICP was higher during active sleep compared to quiet sleep. Multiple regression analysis showed that ICP during active sleep was dependent upon disease severity (unicoronal/ multiple synostosis) and to the baseline ICP level during quiet sleep. Both raised ICP and airway obstruction were more apparent during active sleep. There was a significant correlation between severity of UAO and increased ICP in active sleep. We conclude that obstructive respiratory problems are frequent in the syndromic patients, and can be severe in a large proportion of cases; intracranial hypertension is also frequent in this group. Further studies are required to investigate the possibility of a causal relationship between upper airway obstruction and raised intracranial pressure.
Adjunctive interferon-alpha-2c in stage IIIB/IV small-cell lung cancer: a phase III trial
Authors: Prior C , Oroszy S , Oberaigner W , Schenk E , Kummer F , Aigner K , Hausmaninger H , Peschel C , Huber H
Published: March 2003

Preliminary studies have shown bioactivity of interferons (IFNs) in the treatment of small-cell lung cancer (SCLC). The aim of the present study was to determine whether, in patients with advanced SCLC, a combination of recombinant IFN-alpha-2c and standard induction chemotherapy would improve response rates and survival at acceptable toxicity. Of the 85 patients recruited by 11 centres in Austria, 77 were evaluable for response after induction therapy; of these, 43 were randomized to receive the combined treatment (three cycles each of cyclophosphamide/vincristine/doxorubicin and cisplatin/etoposide plus subcutaneous IFN-alpha-2c), and 34 received chemotherapy alone. After the induction phase, patients in the IFN arm had higher rates of complete (30 vs 15%) and partial remission (42 vs 29%) than those who received chemotherapy alone. Accordingly, there was a lower rate of progressive disease in the interferon arm (21 vs 44%; p < 0.05). Whilst there were no significant differences in time to progression (7.6 vs 5.4 months) patients in the IFN arm survived longer than those in the chemotherapy arm (p < 0.02). Six of the patients treated with IFN (14%) survived for more than 2 yrs, whereas none in the chemotherapy arm did. We conclude that the addition of interferon-alpha-2c to induction chemotherapy may improve response rates and survival in advanced small-cell lung cancer.
Carcinoma of the bronchus in the Yorkshire region of England 1976-1990: trends since 1984
Authors: Connolly CK , Crawford SM , Rider PL , Smith AD , Johnston CF , Muers MF
Published: March 2003

We wished to confirm that, in patients with lung cancer, trends in demography and histology, together with modest improvements in survival, first seen in the 1976-1983 cohorts, continued to 1990. All lung cancer patients resident in Yorkshire are notified to the Cancer Registry, whose database was analysed for this report. A total of 38,275 patients were notified. There was no change in annual notification for males but an increase from 513 to 815 annual notifications in females between 1976 and 1990. Mean age increased by 3 yrs, in males to 67.4 yrs and in females to 67.2 yrs. Histological confirmation rate increased from 43% to 60% (mean age from 60.8 to 64.5 yrs). Annual notifications of adenocarcinoma increased consistently from 108 to 253. Two year surgical survival improved from 37.4 to 44.3%, doubling in subjects aged > or = 70 yrs to 43.8%. Over the 15 year period, there was no improvement in survival aged < 60 yrs, but a significant improvement in the 60-69 and > or = 70 yrs age groups. Analysis of survival by quartiles showed significant improvement at all levels (first interval 20 to 24 days, median 79 to 91 days, third interval 224 to 266 days). The modest improvement in outlook was confirmed, confined to older subjects after 1983, and partially masked by increasing age. Survival after surgery is now independent of age.