Walsh functions: analysis of their properties under Fresnel diffraction

The free-propagation properties of the light field diffracted by an aperture, have been investigated by employing a formalism based on the orthogonal and complete set of Walsh functions. We found an interesting link with the well-known self-imaging phenomenon, which can be used to explain the spatial filtering properties of many optical devices. An experimental result is given in order to illustrate this approach

Field observations of wave and current characteristics on a microtidal reflective beach

At Costa Verde beach, Colombia, an intermediate reflective beach, the contributions of gravity (G) and infragravity (IG) waves to the evolution of the free surface and the cross-shore and alongshore velocities during two climatic periods were determined by applying the continuous wavelet transformation to sensor data recorded in field campaigns. In the dry season, the highest values of IG energy were found in the vicinity of the coastline, due to reflection processes in the área near the foreshore. Additionally, the cross-wavelet and coherence spectra between the free surface and the cross-shore and alongshore velocities allowed the identification of cross-shore and alongshore standing ‘‘leaky’’ waves and standing ‘‘edge’’ waves. In the rainy (wet) season, cross-shore and alongshore progressive leaky waves predominated in the área farthest from the shoreline. Close to the shore, mostly cross-shore standing leaky waves predominated because of reflection dynamics. On Costa Verde beach, the wave breaking is usually of the plunging type, which is characteristic of an intermediate reflective beach. The dimensionless fall velocity parameter (X) indicated that Costa Verde assumes the form of an intermediate ridge-runnel beach in the rainy (wet) season (low swell energy) and an intermediate transverse bar and rip beach in the dry season (high swell energy). This means that the Costa Verde beach tends to have small rip currents and pronounced ‘‘cusps.’’ Despite the lack of conclusive evidence to suggest that the appearance of cusps and rip currents is due to the presence of standing edge waves during the dry season, the data show that during the period of high energy swell, IG waves exist simultaneously with the cusps as small rhythmic systems of rip currents

The potential role of G-CSF in stroke

O fator estimulador de colônias granulocitárias (G-CSF) é uma glicoproteína descrita há mais de vinte anos, e é largamente utilizada para tratamento de estados neutropênicos e no transplante de medula óssea. O G-CSF estimula células-tronco hematopoéticas e regula crucialmente a sobrevivência de neutrófilos maduros, pós-mitóticos, através da inibição da apoptose. Além do efeito sistêmico, mais recentemente tem-se demonstrado uma surpreendente atividade do G-CSF no sistema nervoso central. A administração de G-CSF mobiliza células-tronco e progenitoras da medula óssea para o sangue periférico, que, por sua vez, atravessa a barreira hemato-encefálica (BHE) e se dirige à área acometida do cérebro. A atividade do G-CSF no sistema nervoso central tem sido caracterizada como multimodal, pois, além do efeito mobilizador de células da medula óssea, demonstrou uma ação direta neuroprotetora através de diferentes mecanismos, tais como a atividade antiapoptótica em neurônios, regeneração da vascularização, efeito anti-inflamatório e estimulação da neurogênese endógena. Este relato sumariza a ação do G-CSF no sistema nervoso central e aborda seu potencial para o emprego no acidente vascular cerebral.The granulocyte colony-stimulating-factor (G-CSF) is a glycoproteina which has been described for decades, and it is commonly utilized in the treatment of neutropenic states and bone marrow transplants. G-CSF stimulates hematopoietic stem-cels e crucially regulates the survival of mature neutrophils through a mechanism of apoptosis inhibition. Beyond its systemic effect, recently it has been shown its surprising activity in the central nervous system (CNS). G-CSF administration mobilizes bone marrow stem cells para systemic blood, and those cells cross the blood-brain-barrier e target brain's damaged area. G-CSF's activity in the CNS has been defined as multimodal, because additionally it has been demonstrated a direct neuroprotective action through different mechanisms such as antiapoptotic activity, angiogenesis, anti-inflamatory effect, and stimulation of endogenous neurogenesis. This paper sumarizes G-CSF action in the CNS and approaches its potential para use in stroke

Medida de magnitudes con GeoGebra en la formación de maestros

En este trabajo presentamos una propuesta de trabajo diseñada con GeoGebra centrada en la medida de magnitudes continuas y dirigida a estudiantes de tercer ciclo de Educación Primaria. Esta propuesta se organiza en torno a tres módulos. El primero se centra en el manejo de algunas herramientas básicas de medida e incluye el uso de la cuadrícula de GeoGebra para realizar medidas de manera directa. El segundo módulo explora las condiciones que deben satisfacer tres segmentos para que pueda construirse con ellos un triángulo. El tercer módulo analiza la relación entre área y perímetro en un cuadrilátero. Tras realizar esta actividad con futuros maestros, en el contexto de la primera asignatura de matemáticas que cursan en el Grado en la Universidad de Granada, presentamos el análisis de las respuestas obtenidas

Modified Intracellular-Associated Phenotypes in a Recombinant Salmonella Typhi Expressing S. Typhimurium SPI-3 Sequences

A bioinformatics comparison of Salmonella Pathogenicity Island 3 sequences from S. Typhi and S. Typhimurium serovars showed that ten genes are highly conserved. However three of them are pseudogenes in S. Typhi. Our aim was to understand what functions are lost in S. Typhi due to pseudogenes by constructing a S. Typhi genetic hybrid carrying the SPI-3 region of S. Typhimurium instead of its own SPI-3. We observed that under stressful conditions the hybrid strain showed a clear impairment in resistance to hydrogen peroxide and decreased survival within U937 culture monocytes. We hypothesized that the marT-fidL operon, encoded in SPI-3, was responsible for the new phenotypes because marT is a pseudogen in S. Typhi and has a demonstrated role as a transcriptional regulator in S. Typhimurium. Therefore we cloned and transferred the S. Typhimurium marT-fidL operon into S. Typhi and confirmed that invasion of monocytes was dramatically decreased. Finally, our findings suggest that the genomic and functional differences between SPI-3 sequences have implications in the host specificity of Typhi and Typhimurium serovars

The de novo production of halogenated hydroquinone metabolites by the Andean-Patagonian white-rot fungus Phylloporia boldo

The production of halogenated hydroquinone metabolites such as drosophilin A, drosophilin A methyl ether and chloroneb was investigated in the Andean-Patagonian fungus Phylloporia boldo. These chlorinated compounds were detected in both fruiting bodies and living cultures. Gas chromatography-mass spectrometry (GC-MS) quantification of these molecules was performed in liquid media giving similar values in comparison to previous reports. We observed the concentration of drosophilin A, drosophilin A methyl ether and chloroneb increased in liquid culture supplemented with KCl. Furthermore, chlorinated hydroquinone compounds were not detected using liquid media supplemented with KBr. Instead, brominated aromatic molecules were observed and quantified by gas chromatography-mass spectrometry. We consider these results are relevant for the use of these halogenating microorganisms in biotransformation processes.Fil: Riquelme, C.. Universidad de Concepción; ChileFil: Candia, B.. Universidad de Concepción; ChileFil: Ruiz, D.. Universidad de Concepción; ChileFil: Herrera, M.. Universidad de Concepción; ChileFil: Becerra, J.. Universidad de Concepción; ChileFil: Pérez, C.. Universidad de Concepción; ChileFil: Rajchenberg, Mario. Centro de Investigación y Extensión Forestal Andino Patagónico; Argentina. Provincia del Chubut. Centro de Investigación y Extensión Forestal Andino Patagónico; Argentina. Universidad Nacional de la Patagonia "San Juan Bosco"; ArgentinaFil: Cabrera Pardo, J.R.. University of Utah; Estados Unidos. Universidad del Bio Bio; Chil

Orbital Injection of the SEDSAT Satellite: Tethered Systems Dynamics and Flight Data Analysis

This report deals with the following topics which are all related to the orbital injection of the SEDSAT satellite: Dynamics and Stability of Tether Oscillations after the First Cut. The dynamics of the tether after the first cut (i.e., without the Shuttle attached to it) is investigated. The tether oscillations with the free end are analyzed in order to assess the stability of the rectilinear configuration in between the two tether cuts; analysis of Unstable Modes. The unstable modes that appear for high libration angles are further investigated in order to determine their occurrences and the possible transition from bound librations to rotations; Orbital Release Strategies for SEDSAT. A parametric analysis of the orbital decay rate of the SEDSAT satellite after the two tether cuts has been carried out as a function of the following free parameters: libration amplitude at the end of deployment, deviation angle from LV at the first cut, and orbital anomaly at the second cut. The values of these parameters that provide a minimum orbital decay rate of the satellite (after the two cuts) have been computed; and Dynamics and Control of SEDSAT. The deployment control law has been modified to cope with the new ejection velocity of the satellite from the Shuttle cargo bay. New reference profiles have been derived as well as new control parameters. Timing errors at the satellite release as a function of the variations of the initial conditions and the tension model parameters have been estimated for the modified control law

Dynamic earthquake triggering response tracks evolving unrest at Sierra Negra volcano, Galápagos Islands

The propensity for dynamic earthquake triggering is thought to depend on the local stress state and amplitude of the stress perturbation. However, the nature of this dependency has not been confirmed within a single crustal volume. Here, we show that at Sierra Negra volcano, Galápagos Islands, the intensity of dynamically triggered earthquakes increased as inflation of a magma reservoir elevated the stress state. The perturbation of short-term seismicity within teleseismic surface waves also increased with peak dynamic strain. Following rapid coeruptive subsidence and reduction in stress and background seismicity rates, equivalent dynamic strains no longer triggered detectable seismicity. These findings offer direct constraints on the primary controls on dynamic triggering and suggest that the response to dynamic stresses may help constrain the evolution of volcanic unrest