Numerical and Theoretical Studies of Noise Effects in the Kauffman Model

In this work we analyze the stochastic dynamics of the Kauffman model evolving under the influence of noise. By considering the average crossing time between two distinct trajectories, we show that different Kauffman models exhibit a similar kind of behavior, even when the structure of their basins of attraction is quite different. This can be considered as a robust property of these models. We present numerical results for the full range of noise level and obtain approximate analytic expressions for the above crossing time as a function of the noise in the limit cases of small and large noise levels.Comment: 24 pages, 9 figures, Submitted to the Journal of Statistical Physic

Vertex routing models

A class of models describing the flow of information within networks via routing processes is proposed and investigated, concentrating on the effects of memory traces on the global properties. The long-term flow of information is governed by cyclic attractors, allowing to define a measure for the information centrality of a vertex given by the number of attractors passing through this vertex. We find the number of vertices having a non-zero information centrality to be extensive/sub-extensive for models with/without a memory trace in the thermodynamic limit. We evaluate the distribution of the number of cycles, of the cycle length and of the maximal basins of attraction, finding a complete scaling collapse in the thermodynamic limit for the latter. Possible implications of our results on the information flow in social networks are discussed.Comment: 12 pages, 6 figure

Static Pairwise Annihilation in Complex Networks

We study static annihilation on complex networks, in which pairs of connected particles annihilate at a constant rate during time. Through a mean-field formalism, we compute the temporal evolution of the distribution of surviving sites with an arbitrary number of connections. This general formalism, which is exact for disordered networks, is applied to Kronecker, Erd\"os-R\'enyi (i.e. Poisson) and scale-free networks. We compare our theoretical results with extensive numerical simulations obtaining excellent agreement. Although the mean-field approach applies in an exact way neither to ordered lattices nor to small-world networks, it qualitatively describes the annihilation dynamics in such structures. Our results indicate that the higher the connectivity of a given network element, the faster it annihilates. This fact has dramatic consequences in scale-free networks, for which, once the ``hubs'' have been annihilated, the network disintegrates and only isolated sites are left.Comment: 7 Figures, 10 page

Communities of Practice: A Consortium of Catholic Elementary Schools’ Collaborative Journey

Archdioceses and dioceses around the United States continue to brainstorm innovative ways to market their schools in an education system that provides a number of choices to parents and their children. Applying Wenger’s (1998) learning theory entitled Communities of Practice (COPs), the purpose of this case study was to investigate one such plan to improve the viability of three inner-city Catholic elementary schools that had similar missions, were located within just a few miles of one another, and served the same neighborhoods of a working-class, culture-rich Latino community in Southern California. Data collection included in-depth interviews with principals and teachers and site visits that involved observations of classroom lessons and joint faculty meetings. Data were analyzed using a two-step coding scheme that was grounded in the main tenets of the theoretical framework. Findings showed the early stages of an interschool consortium that consisted of multiple levels of distributed leadership and the development and maintenance of COPs among principals, teachers, parents, and students. The findings of this study offer a potential model for Catholic schools in similar contexts. Comunidades de práctica: camino colaborador de un consorcio de escuelas elementales católicas Las archidiócesis y diócesis de Estados Unidos siguen compartiendo maneras innovadoras para publicitar sus escuelas en un sistema educativo que provee una amplia variedad de opciones a los padres y a sus hijos. Aplicando la teoría de aprendizaje de Wenger (1998) llamada Comunidades de práctica (COP), el objetivo de este estudio de caso fue investigar uno de estos planes para mejorar la viabilidad de tres escuelas elementales católicas del centro urbano que tenían misiones similares, estaban separadas por pocos quilómetros y servían a los mismos barrios de una comunidad de clase trabajadora, de riqueza cultural latina en el sur de California. La recolección de información incluyó entrevistas exhaustivas a directores y profesores, y visitas a los centros que supusieron observaciones de clases y de reuniones de profesorado. Se analizaron los datos usando un sistema de codificación de dos pasos basado en los principios del marco teórico. Los resultados revelaron las etapas tempranas de un consorcio interescolar que consistía en múltiples niveles y distribución del liderazgo y del desarrollo, así como mantenimiento de los COP entre directores, profesores, padres y estudiantes. Los resultados de este estudio ofrecen un modelo potencial para las escuelas católicas que se encuentren en contextos similares. Palabras clave: consorcio de escuelas, liderazgo distribuido Communautés de pratiques : le parcours collaboratif d\u27un consortium d\u27écoles catholiques primaires Les diocèses et archidiocèses aux États-Unis continuent de réfléchir à des manières innovantes de faire connaître leurs écoles dans un système éducatif présentant de nombreux choix aux parents et leurs enfants. Cette étude de cas, qui applique la théorie de Wenger sur l\u27apprentissage (1998), intitulée les Communautés de pratiques (CDP), avait pour but de faire des recherches sur un tel plan pour améliorer la viabilité de trois écoles catholiques primaires dans des cités, aux missions similaires, et situées à quelques kilomètres les unes des autres, dans les mêmes quartiers de classe ouvrière, imprégnés de culture latino-américaine, dans le sud de la Californie. Les données recueillies comportaient des entretiens approfondis avec les chefs d\u27établissement et les enseignants et des visites sur place contenant des observations en salle de classe et des réunions d\u27enseignants. Les données ont été analysées à l\u27aide d\u27un mécanisme de codage en deux étapes, fondé sur les préceptes principaux du cadre théorique. Les constatations ont montré les premières phases d\u27un consortium inter-écoles qui se composait de plusieurs niveaux de leadership partagé et l\u27élaboration et la maintenance des CDP parmi les chefs d\u27établissements, les enseignants, les parents et les élèves. Les conclusions de cette étude constituent un modèle potentiel pour les écoles catholiques dans des contextes similaires. Mots-clés : consortium d\u27écoles, leadership partag

On-site detection of equid alphaherpesvirus 3 in perineal and genital swabs of mares and stallions

Equine coital exanthema (ECE) is an infectious, venereally transmitted muco-cutaneous disease affecting mares and stallions, caused by equid alphaherpesvirus 3 (EHV3). Diagnostic tools for rapid identification of EHV3 are of primary importance to diminish the risk of EHV3 dissemination at the time of breeding. In the last years, it has been shown that the performance of the insulated-isothermal polymerase chain reaction (iiPCR) is comparable to virus isolation, nested PCR and real-time PCR (qPCR) in detecting pathogens of various animal species. Analytical sensitivity and specificity of the iiPCR were compared with a qPCR, using a plasmid containing the target region of the EHV3 glycoprotein G gene and an Argentinian EHV3 isolate (E/9283/07 C3A). In order to evaluate the diagnostic performance of the iiPCR, nucleic acids of 85 perineal and genital swabs (PGS) of mares and stallions were extracted by tacoTM mini and tested by both techniques. EHV3 was detected in 46 and 45 of the 85 PGS by the iiPCR and qPCR, respectively. There was almost perfect agreement between the two diagnostic methods (98.82%; 95% CI: 95.03–100%; κ = 0.98). The iiPCR had a limit of detection of 95.00% at 6 genome equivalents per reaction and a detection endpoint for viral DNA comparable to that of the qPCR, and did not react with six non-targeted equine pathogens. The iiPCR represents a sensitive and specific method for the rapid on-site diagnosis of EHV3 infection. Its routinely implementation in breeding facilities, and artificial insemination and embryo transfer centers, will contribute to prevent the dissemination of this venereal, highly contagious disease in horses.Fil: Vissani, María Aldana. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Instituto Nacional de Tecnología Agropecuaria; ArgentinaFil: Tordoya, Maria Silvia. Instituto Nacional de Tecnología Agropecuaria; ArgentinaFil: Tsai, Y.-L.. GeneReach; Estados UnidosFil: Lee, P.-Y.A.. GeneReach; Estados UnidosFil: Shen, Y.-H.. GeneReach; Estados UnidosFil: Lee, F.-C.. GeneReach; Estados UnidosFil: Wang, H.-T.T.. GeneReach; Estados UnidosFil: Parreño, Gladys Viviana. Instituto Nacional de Tecnología Agropecuaria; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Barrandeguy, María Edith. Instituto Nacional de Tecnología Agropecuaria; Argentina. Universidad del Salvador. Escuela de Veterinaria; Argentin

The Naso-Axial Line: a new method of accurately predicting the inferior limit of the endoscopic endonasal approach to the craniocervical junction

Background: Endoscopic approaches to anterior pathology of the craniocervical junction (CVJ) have arisen as alternatives to open approaches. Understanding and predicting the limits to the endoscopic approach to CVJ is important in surgical planning. The endoscopic endonasal approach (EEA) is commonly used, thus we sought to develop a method that accurately predicts the inferior limit of this to the CVJ. The method developed was compared with methods currently used to predict the same. Methods: Nine fresh-frozen adult cadaver heads were used for anatomical dissection. Preoperative and postoperative volumetric computerized tomographic scans were performed to compare the naso-axial line (NAL) vs. naso-palatine (NPL, or Kassam, line) used to predict the inferior limit of the EEA to the actual extent of surgical dissection. Results: The mean differences between the NAL and the actual inferior surgical exposure of EEA at the C2 cortex (anterior and posterior) were both 0.3 mm. Anatomically, the actual inferior surgical limit ranged from the dens to the upper half of the C2 body, which matched that predicted by the NAL. The NPL predicted an inferior EEA limit at a much lower range than the actual\u2014from the lower half of the C2 body to the superior endplate of C3. Using the least squares means (LSM) method to estimate the deviation from postsurgical measurements, we found no difference between the NAL and the actual inferior surgical limit (LSM, 0; P\u2009=\u20091.0). In contrast, the NPL predicted a significantly lower EEA limit than the actual surgical limit (LSM, 13.3; P\u2009<\u20090.001). Conclusion: The naso-axial line accurately predicts the inferior limit of the EEA, which ranges from the dens to the upper half of C2. This new method can be used in presurgical planning to assess the suitability of the EEA to craniovertebral junction pathology

Metaphysics and Perception of the Form of Christ. European Heritage in the Theological Aesthetics of Hans Urs von Balthasar.

The following pages present the central intuition of the theological aesthetics of Hans Urs von Balthasar, Jesus Christ as the form of God’s revelation, highlighting its ability to integrate the metaphysical tradition, including myth, which is evident in the Bible itself and in theology. Europe has inherited not only a culture but also a worldview shaped around the Christian mysteries, yet this heritage is effective only in a love that can see, honor, welcome, and serve the absolute Love that became incarnate and that sacrificed itself for all men.Estas páginas presentan la intuición central de la estética teológica de Hans Urs von Balthasar, Jesucristo como forma de la revelación de Dios, subrayando su capacidad de integrar la tradición metafísica, incluido el mito, lo que es constatable en la Biblia misma y en la teología. Europa ha heredado no sólo una cultura, sino una visión configurada del mundo en torno a los misterios cristianos, pero esta herencia tiene su vigor sólo en el amor que sabe ver, honrar, acoger y servir al Amor absoluto encarnado y sacrificado por los hombres

Transferring orbital and spin angular momenta of light to atoms

Light beams carrying orbital angular momentum, such as Laguerre-Gaussian beams, give rise to the violation of the standard dipolar selection rules during the interaction with matter yielding, in general, an exchange of angular momentum larger than hbar per absorbed photon. By means of ab initio 3D numerical simulations, we investigate in detail the interaction of a hydrogen atom with intense Gaussian and Laguerre-Gaussian light pulses. We analyze the dependence of the angular momentum exchange with the polarization, the orbital angular momentum, and the carrier-envelope phase of light, as well as with the relative position between the atom and the light vortex. In addition, a quantum-trajectory approach based on the de Broglie-Bohm formulation of quantum mechanics is used to gain physical insight into the absorption of angular momentum by the hydrogen atom

Schumpeterian economic dynamics as a quantifiable minimum model of evolution

We propose a simple quantitative model of Schumpeterian economic dynamics. New goods and services are endogenously produced through combinations of existing goods. As soon as new goods enter the market they may compete against already existing goods, in other words new products can have destructive effects on existing goods. As a result of this competition mechanism existing goods may be driven out from the market - often causing cascades of secondary defects (Schumpeterian gales of destruction). The model leads to a generic dynamics characterized by phases of relative economic stability followed by phases of massive restructuring of markets - which could be interpreted as Schumpeterian business `cycles'. Model timeseries of product diversity and productivity reproduce several stylized facts of economics timeseries on long timescales such as GDP or business failures, including non-Gaussian fat tailed distributions, volatility clustering etc. The model is phrased in an open, non-equilibrium setup which can be understood as a self organized critical system. Its diversity dynamics can be understood by the time-varying topology of the active production networks.Comment: 21 pages, 11 figure