Degradación de estructuras urbanas generada por crecimiento de plantas y actividad microbiana

The purpose of this study was to isolate microorganisms associated to surface-affected concrete structures and to measure the in vitro dissolution of concrete based on the release of elements such as calcium and silicon. Although many microorganisms were detected only a fungus was capable of significantly decreasing the culture medium pH and releasing both elements. The molecular characterization allowed to identify the microorganism as Aspergillus carbonaurius, a citric-acid producing fungus that dissolved concrete in the in vitro test. After seven days of incubation, the soluble calcium concentration in the uninoculated culture medium containing concrete was 172.3 mg/L, while in the inoculated medium it was 525.0 mg/L. The soluble silicon concentration in the uninoculated medium was 10.3 mg/L, while in the inoculated medium it was 50.1 mg/L. These findings showed that plants and microorganisms rendered a synergistic effect accelerating the biodeterioration of concrete.El objetivo de este estudio fue aislar microorganismos de la superficie de estructuras urbanas de concreto deterioradas y medir su capacidad para disolver in vitro muestras de concreto, basada en la liberación de elementos como el calcio y el silicio. De todos los microorganismos aislados sólo un hongo fue capaz de disminuir el pH y disolver el concreto. Este hongo fue identificado a nivel molecular como Aspergillus carbonaurius, un productor de ácido cítrico. Después de siete días de incubación, se encontró que la concentración de calcio soluble en el medio de cultivo no inoculado fue 172,3 mg/L, mientras que en el medio inoculado era de 525,0 mg/L. La concentración de silicio soluble en el medio no inoculado fue de 10,3 mg/L, mientras que en el medio inoculado fue de 50,1 mg/L. Estos hallazgos mostraron que las plantas y los microorganismos producen un efecto sinérgico que acelera el biodeterioro del concreto

Forgiveness and politics : Reading Matthew 18:21–35 with survivors of armed conflict in Colombia

This project was made possible through the support of a grant from the Templeton World Charity Foundation (TWCF). The authors thank Fernando Abilio Mosquera-Brand, Milton Alfonso Acosta-Benítez, Francis Alexis Pineda, and Laura Cadavid-Valencia, who along with G.M.C. and R.W.H. carried out the fieldwork. The authors also thank those who commented on early versions of this article at presentations in Berlin, Oxford, Boston, Medellín, and Bogotá, especially David López-Amaya.Peer reviewedPublisher PD

Simulating noisy quantum protocols with quantum trajectories

The theory of quantum trajectories is applied to simulate the effects of quantum noise sources induced by the environment on quantum information protocols. We study two models that generalize single qubit noise channels like amplitude damping and phase flip to the many-qubit situation. We calculate the fidelity of quantum information transmission through a chaotic channel using the teleportation scheme with different environments. In this example, we analyze the role played by the kind of collective noise suffered by the quantum processor during its operation. We also investigate the stability of a quantum algorithm simulating the quantum dynamics of a paradigmatic model of chaos, the baker's map. Our results demonstrate that, using the quantum trajectories approach, we are able to simulate quantum protocols in the presence of noise and with large system sizes of more than 20 qubits.Comment: 11 pages, 7 fig

Ultrashort-pulse laser with an intracavity phase shaping element

A novel ultrashort-pulse laser cavity configuration that incorporates an intracavity deformable mirror as a phase control element is reported. A user-defined spectral phase relation of 0.7 radians relative shift could be produced at around 1035 nm. Phase shaping as well as pulse duration optimization was achieved via a computer-controlled feedback loop

Resolución de problemas por medio de matemática experimental: uso de software de geometría dinámica para la construcción de un lugar geométrico desconocido

A través de un ejemplo de geometría euclidiana y utilizando el programa de geometría dinámica Cabri Géomètre, mostraremos cómo seguir un proceso para la solución de problemas mediante la matemática experimental que comprende dos momentos: la experimentación y la formalización. El problema que resolvemos es el siguiente: Dado un triángulo cualquiera, encontrar el lugar geométrico de todos los puntos en el plano tales que el triángulo simétrico lateral del triángulo dado sea rectángulo.Through an example of Euclidean geometry and using the dynamic geometry software Cabri Géomètre, we show here how to follow a process to solve problems via experimental mathematics which include two phases: experimentation and formalization. The problem we solve is as follows: Given a triangle, find the locus for all points in the plane such that the lateral symmetrical triangle to triangle given be rectangle

Survival in pulmonary fibrosis combined with emphysema: likely defined by characteristics of specific patient subpopulations

Authors' Reply to letter from Cottin et al

Carbonatación de un hormigón hibrido con alto contenido de escoria siderurgica de alto horno y su impacto en la corrosión del acero estructural

The aim of this research was to study the carbonation resistance of a blast furnace slag concrete (80% GBFS/20%OPC), with and without alkaline activation, and its influence on the corrosion of structural reinforcement. An OPC-based concrete produced under the same specifications was used as a reference material. To do this, the material was subjected to an accelerated carbonation process under controlled conditions (65% relative humidity, 1% CO2, 25°C). The half-cell potential (Ecorr), linear polarization resistance (LPR) tests showed that both concretes based on GBFS led to depassivation of the reinforcing steel at approximately 99 days, which is the time required for full carbonation of the evaluated concretes.El objetivo de esta investigación fue estudiar la resistencia a la carbonatación de un hormigón a base de escoria granulada de alto horno (80% GBFS/20%OPC), con y sin activación alcalina, y su influencia sobre la corrosión del acero estructural. Un hormigón basado en cemento portland producido con las mismas especificaciones fue usado como material de referencia. Para ello, el material fue sometido a un proceso de carbonatación acelerada bajo condiciones controladas (Humedad Relativa 65 %, 1% CO2, 25 °C). Los ensayos de potencial de media celda (Ecorr) y Resistencia a la polarización lineal (LPR) mostraron que los aceros estructurales aproximadamente a los 99 días alcanzan la despasivación en los hormigones basados en escoria, coincide este tiempo con el requerido para la completa carbonatación de los hormigones evaluados

Phylogenetic evidence from freshwater crayfishes that cave adaptation is not an evolutionary dead-end.

Caves are perceived as isolated, extreme habitats with a uniquely specialized biota, which long ago led to the idea that caves are evolutionary dead-ends. This implies that cave-adapted taxa may be doomed for extinction before they can diversify or transition to a more stable state. However, this hypothesis has not been explicitly tested in a phylogenetic framework with multiple independently evolved cave-dwelling groups. Here, we use the freshwater crayfish, a group with dozens of cave-dwelling species in multiple lineages, as a system to test this hypothesis. We consider historical patterns of lineage diversification and habitat transition as well as current patterns of geographic range size. We find that while cave-dwelling lineages have small relative range sizes and rarely transition back to the surface, they exhibit remarkably similar diversification patterns to those of other habitat types and appear to be able to maintain a diversity of lineages through time. This suggests that cave adaptation is not a dead-end for freshwater crayfish, which has positive implications for our understanding of biodiversity and conservation in cave habitats