Conductive-probe atomic force microscopy characterization of silicon nanowire

The electrical conduction properties of lateral and vertical silicon nanowires (SiNWs) were investigated using a conductive-probe atomic force microscopy (AFM). Horizontal SiNWs, which were synthesized by the in-plane solid-liquid-solid technique, are randomly deployed into an undoped hydrogenated amorphous silicon layer. Local current mapping shows that the wires have internal microstructures. The local current-voltage measurements on these horizontal wires reveal a power law behavior indicating several transport regimes based on space-charge limited conduction which can be assisted by traps in the high-bias regime (> 1 V). Vertical phosphorus-doped SiNWs were grown by chemical vapor deposition using a gold catalyst-driving vapor-liquid-solid process on higly n-type silicon substrates. The effect of phosphorus doping on the local contact resistance between the AFM tip and the SiNW was put in evidence, and the SiNWs resistivity was estimated

Ensemble Analysis of Angiogenic Growth in Three-Dimensional Microfluidic Cell Cultures

We demonstrate ensemble three-dimensional cell cultures and quantitative analysis of angiogenic growth from uniform endothelial monolayers. Our approach combines two key elements: a micro-fluidic assay that enables parallelized angiogenic growth instances subject to common extracellular conditions, and an automated image acquisition and processing scheme enabling high-throughput, unbiased quantification of angiogenic growth. Because of the increased throughput of the assay in comparison to existing three-dimensional morphogenic assays, statistical properties of angiogenic growth can be reliably estimated. We used the assay to evaluate the combined effects of vascular endothelial growth factor (VEGF) and the signaling lipid sphingoshine-1-phosphate (S1P). Our results show the importance of S1P in amplifying the angiogenic response in the presence of VEGF gradients. Furthermore, the application of S1P with VEGF gradients resulted in angiogenic sprouts with higher aspect ratio than S1P with background levels of VEGF, despite reduced total migratory activity. This implies a synergistic effect between the growth factors in promoting angiogenic activity. Finally, the variance in the computed angiogenic metrics (as measured by ensemble standard deviation) was found to increase linearly with the ensemble mean. This finding is consistent with stochastic agent-based mathematical models of angiogenesis that represent angiogenic growth as a series of independent stochastic cell-level decisions

Caracterización del desafío de educación superior para implementar un modelo de puntuación de ensayos automatizado para universidades con un sistema de evaluación de aprendizaje tradicional actual

Higher education is currently challenged to respond to a massive interest in learning with a current model that shows increasing evidence of too much cost, effort and decreasing efficacy of the operational learning process. Artificial intelligence has gained presence as a solution, but the integration process is already reporting problems and will not be implemented easily, in particular for universities with low degree of automation integrated to their systems. Universities need to quickly adapt and develop organizational and individual competencies, and clarity about the elements for new learning evaluation systems. This work contributes to propose a model to help universities to define these new systems making the most of artificial intelligence tools for academic essays scoring

Caracterización del desafío de educación superior para implementar un modelo automatizado de puntuación de ensayos para universidades con un sistema de evaluación de aprendizaje tradicional actual

La educación superior actualmente tiene el desafío de responder a un interés masivo en el aprendizaje con un modelo actual que muestra evidencia creciente de demasiado costo, esfuerzo y disminución de la eficacia del proceso de aprendizaje operacional. La inteligencia artificial ha ganado presencia como una solución, pero el proceso de integración ya está reportando problemas y no se implementará fácilmente, en particular para las universidades con bajo grado de automatización integrada a sus sistemas. Las universidades deben adaptarse y desarrollar rápidamente competencias organizativas e individuales, y claridad sobre los elementos para los nuevos sistemas de evaluación de aprendizaje. Este trabajo contribuye a proponer un modelo para ayudar a las universidades a definir estos nuevos sistemas que aprovechan al máximo las herramientas de inteligencia artificial para la calificación de ensayos académicos. © 2019, Springer Nature Switzerland A

General scaling in bidirectional flows of self-avoiding agents

The analysis of the classical radial distribution function of a system provides a possible procedure for uncovering interaction rules between individuals out of collective movement patterns. A formal extension of this approach has revealed recently the existence of a universal scaling in the collective spatial patterns of pedestrians, characterized by an effective potential of interaction V(τ) conveniently defined in the space of the times-to-collision τ between the individuals. Here we significantly extend and clarify this idea by exploring numerically the emergence of that scaling for different scenarios. In particular, we compare the results of bidirectional flows when completely different rules of self-avoidance between individuals are assumed (from physical-like repulsive potentials to standard heuristic rules commonly used to reproduce pedestrians dynamics). We prove that all the situations lead to a common scaling in the t-space both in the disordered phase (V(τ) ~ τ) and in the lane-formation regime (V(τ) ~ τ), independent of the nature of the interactions considered. Our results thus suggest that these scalings cannot be interpreted as a proxy for how interactions between pedestrians actually occur, but they rather represent a common feature for bidirectional flows of self-avoiding agents