Ecosystem transformations in response to environmental fluctuations

Ecosystems, which are intricate amalgams of biological communities and their surrounding environments, continually evolve under the influence of their myriad interactions. The world is currently facing intensifying environmental fluctuations. Understanding general trends in ecosystem transformations in response to environmental fluctuations and elucidating the underlying mechanisms are thus critical challenges. In this study, we used a model ecosystem approach to investigate ecosystem alterations caused by escalating environmental fluctuations. We analyzed two distinct models: a stochastic ecosystem model with a spatial structure, and a differential equation model for resource competition. We found that environmental fluctuations tend to shift multi-species coexistence toward the dominance of specific species. We also categorized biological species as specialists or generalists and discovered that which of these groups becomes the dominant species depends on the intensity and frequency of environmental fluctuations. We also determined that a qualitative change in the diversity-stability relationship depends on the period of environmental fluctuations. These results underscore the need to explicitly consider the type of perturbation when discussing ecological transitions and the stability of ecosystems. Our findings advance understanding of the mechanisms underlying how environmental changes reshape ecosystems and offer insights into ecosystem sustainability in the face of future environmental perturbations.Comment: 9 pages, 4 figure

The Relationship between Young Children’s Source Monitoring and Serial Order or Item Information in Verbal or Visuospatial Working Memory Tasks

In this study, we examined the relationship between young children’s source monitoring of external information and serial order or item information in the working memory task. Seventy five children (mean age of the moon = 61.9) participated in Study 1. They were presented with three slides and were asked to remember what items appeared in which order, in which position, and how many items came out on each slide. A partial correlation showed that the score of the verbal serial order information and visuospatial position information were positively related to the score of the source monitoring task, even after controlling for age. We corrected the tasks and conducted study 2 for 72 participants (mean age of the moon = 60.3). Even after controlling for age and vocabulary, the score of the verbal item information and visuospatial position information showed a positive correlation with the score of the source monitoring tasks. Thus, it was suggested that accurate remembering of verbal item information and visuospatial position information is related to accurate source monitoring of external information

幼児における外部情報のソースモニタリングとワーキングメモリの関連

内容の要約広島大学(Hiroshima University)博士(心理学)Doctor of Philosophy in Psychologydoctora

Constraints on small-field axion inflation

We study general class of small-field axion inflations which are the mixture of polynomial and sinusoidal functions suggested by the natural and axion monodromy inflations. The axion decay constants leading to the successful axion inflations are severely constrained in order not to spoil the Big-Bang nucleosynthesis and overproduce the isocurvature perturbation originating from the QCD axion. We in turn find that the cosmologically favorable axion decay constants are typically of order the grand unification scale or the string scale which is consistent with the prediction of closed string axions.Comment: 17 pages, 6 figures; v2 published versio

Ridge Regression, Hubness, and Zero-Shot Learning

This paper discusses the effect of hubness in zero-shot learning, when ridge regression is used to find a mapping between the example space to the label space. Contrary to the existing approach, which attempts to find a mapping from the example space to the label space, we show that mapping labels into the example space is desirable to suppress the emergence of hubs in the subsequent nearest neighbor search step. Assuming a simple data model, we prove that the proposed approach indeed reduces hubness. This was verified empirically on the tasks of bilingual lexicon extraction and image labeling: hubness was reduced with both of these tasks and the accuracy was improved accordingly.Comment: To be presented at ECML/PKDD 201

New insights on the fundamentals and modeling of the external sulfate attack in concrete structures

The external sulfate attack (ESA) is a complex degradation process typically compromising the durability of underground foundations, nuclear or industrial waste containments and tunnel linings exposed to sulfate solutions. The structures affected usually remain covered its entire service life, which compromises the detection of this phenomenon before severe material degradation has occurred. Once diagnosed, the large size and criticality of the typical structures affected greatly limit the efficiency of the remedial actions. Consequently, monitoring of the evolution of the structural behavior is often the only applicable measure. This scenario places the development of reliable tools to assist the design of sulfate-resisting concrete structures and assess the risk of ESA in existing properties as key challenges for structural durability. The present thesis aims to advance knowledge in this field by presenting important contributions in three different research lines: numerical modeling of the ESA, role of porosity during the attack and the relevance of reproducing field-like conditions on ESA assessments. Advances on the ESA numerical modelization led to the development of a chemo-transport-mechanical model and a simplified assessment methodology. The former simulates the effects of ionic transport, chemical reactions, degradation mechanisms and the mechanical response of the structure. The validations performed indicate that the model captures the importance of the location of the ettringite formed within the pore network and provides a fair quantification of the overall expansions. The simplified assessment methodology evaluates the risk of failure during the ESA based on the aggressiveness of the media, the reactivity and mechanical properties of the material and the geometric characteristics and service life of the element under attack, without resorting to complex iterative algorithms. Unlike current design guidelines, the application of this simplified procedure allows the definition of flexible and optimized precautionary measures for each application. The second research line involved an extensive experimental program that led to the formulation of a conceptual model to explain the role of porosity during the ESA. The results obtained indicate that high durability against the attack might be achieved by limiting the penetration of sulfates or increasing the capacity of the matrix to accommodate expansive products. Both approaches correspond to opposing pore characteristics of the matrix: the former is usually associated with low porosities while the latter requires matrices with high porosities. These results question the common perception that high porosities are always negative for ESA durability and open up the possibility to design sulfate-resisting materials by increasing the capacity of the matrix to accommodate expansive phases. The third research line evaluates the influence of early sulfate exposure and the effects of confinement on the ESA by two experimental programs. The first study suggests that the delayed exposition to sulfates commonly adopted in accelerated laboratory tests might lead to imprecise damage estimations for structures cast in situ. In these cases, it is recommended to expose the samples to sulfates shortly after casting. The second study suggests that assessing sulfate resistance on specimens in free-expanding conditions might not be representative of the behavior of real structures where the attack is developed in combination with confining conditions. Results indicate that compressive stresses generated by confinement interact with the normal development of the attack by limiting or delaying the appearance of micro-cracks and reducing the amount of ettringite crystals exerting expansive pressures.El ataque sulfático externo (ASE) es un proceso de degradación complejo que afecta principalmente la durabilidad de estructuras de cimentación, contenedores de residuos nucleares o industriales y revestimientos de túneles. Dichas estructuras suelen permanecer enterradas toda su vida útil, lo que compromete la detección del fenómeno antes de que se hayan desarrollado altos niveles de degradación. Una vez detectado, el tamaño e importancia estratégica de las estructuras afectadas limitan las opciones de reparación y su eficacia. Debido a ello, habitualmente la única acción posible consiste en la monitorización de la evolución del comportamiento estructural. Este escenario sitúa el desarrollo de herramientas para el diseño de estructuras resistentes a sulfatos y la evaluación del fenómeno en propiedades existentes como desafíos clave para la durabilidad de estructuras enterradas. Esta tesis doctoral aspira a profundizar el conocimiento en torno a esta temática mediante contribuciones relevantes en tres líneas de investigación: la modelización numérica del ASE, el rol de la porosidad durante el ataque y la relevancia de reproducir condiciones de campo en la evaluación del ASE. Avances en el campo de la modelización numérica han dado lugar a un modelo avanzado y una metodología de evaluación simplificada del ASE. El primero se basa en la simulación de procesos de transporte iónico, reacciones químicas, mecanismos de degradación y respuesta mecánica de la estructura. Las validaciones realizadas indican que el modelo refleja la importancia de la localización de la etringita dentro de la red porosa y proporciona estimaciones ajustadas de las expansiones generadas. La metodología de evaluación simplificada mide el riesgo de fallo estructural basándose en la agresividad del medio, la reactividad y propiedades mecánicas del material y las características geométricas y vida útil del elemento atacado, sin recurrir a algoritmos iterativos. A diferencia de las guías de diseño actuales, su aplicación permite la definición de medidas preventivas ajustadas a cada aplicación. La segunda línea de investigación ha dado lugar a un modelo conceptual que explica el rol de la porosidad durante el ASE. Los resultados obtenidos indican que se pueden alcanzar altas resistencias al ataque mediante la limitación de la penetración de sulfatos en la estructura o incrementando la capacidad de la matriz de acomodar fases expansivas. Los dos enfoques se corresponden a características porosas opuestas de la matriz. La primera se suele asociar a bajas porosidades mientras que la segunda se maximiza en porosidades altas. Los resultados obtenidos cuestionan la idea de que porosidades altas siempre son negativas para la durabilidad ante el ASE y abre la posibilidad de diseñar materiales resistentes a sulfatos incrementando la capacidad de acomodar fases expansivas. La tercera línea de investigación evalúa la influencia de la exposición temprana a sulfatos y los efectos del confinamiento en el ASE. Resultados referentes al primer estudio indican que una exposición tardía a los sulfatos como la empleada en la mayoría de ensayos acelerados puede conllevar a estimaciones incorrectas del daño generado en estructuras fabricadas in situ. El segundo estudio, referente a los efectos del confinamiento, sugiere que el uso de probetas en condiciones de expansión libre puede no ser adecuado para reproducir los efectos del ASE en estructuras donde el ataque se desarrolla en condiciones confinadas. Las tensiones de compresión generadas interactúan con el desarrollo normal del ataque limitando o retardando la aparición de micro-fisuras y reduciendo la cantidad de cristales de etringita creciendo en condiciones confinadas y por ende, ejerciendo presiones expansivas.Postprint (published version

The Function of Religious Language in the Media: A Comparative Analysis of the Japanese, German and American Newspaper Coverage about the 2011 Great East Japan Earthquake and Tsunami

When an incident or event in a certain region will be reported by the mass media in a different language, the choice of expressions, the perspective and aim of their message will differ. This study analyzes the news coverage of events related to the 2011 Great East Japan Earthquake and Tsunami in German, American and Japanese newspapers. It will aim to uncover expressional differences in the coverage on a similar topic reported in different languages. This research especially focuses on the use of religious language in the coverage, which in this paper refers to religious metaphors and symbols originating from a Christian context. Previous research shows that the use of religious language in the media, affects consumers mentally and emotionally. Based on that theory, this study compares how religious language is used in the coverage and tries to clarify the functions of religious expressions through a critical discourse analysis. The results show that religious language appears continuously in German and American news reports related to the disaster. Religious language is mostly used symbolically as well as metaphorically in order to illustrate the destruction caused by the earthquake, tsunami and nuclear disaster, while at the same time conveying emotions such as the fear of the victims. It is also used to describe the difficulties, suffering and hope of the people in the disaster-hit area. Moreover religious language provokes emotions in the readers and makes it easier for them to understand the situation in Japan as well as the feelings of the disaster refugees.  A difference between the German and American news coverage was seen in the description of the situation at the nuclear power plant and the state of the victims in Fukushima and the Tohoku region. In Germany, religious language can change the viewpoint of and provoke emotions in the readers. It is also employed to emphasize domestic social and political problems related to German energy policy