Wavelet analysis of the ionospheric response at mid-latitudes during the April 200 storm using magnetograms and vTEC from GPS

In this work we pursue the idea of computing a parameter that allows us to estimate the local ionospheric response to a geospheric event that triggers an ionospheric storm. For that, wavelet technique has been chosen because of its ability to analyze non-stationary signals. The advantage of the time-frequency analysis method called Wavelet Transform resides in providing information not only about the frequencies of the event but also about its location in the time series. Specifically, we compute the Scale Average Wavelet Power (SAWP) of two parameters that describe the local geomagnetic field variation at the Earth surface caused by a geospheric storm and ionospheric response to the storm event. In particular, we propose the time delay between the maximum values of SAWP applied to the vTEC (vertical Total Electron Content) and the horizontal component of the geomagnetic field (H) variations as parameters to characterize the local behavior of the ionospheric storm. We applied the parameter to the geomagnetic and ionospheric disturbances caused by a coronal mass ejection (CME) that took place on April 4, 2000. We used vTEC values computed from GPS observations and H at the surface of the Earth, measured in stations near to each GPS station chosen. The vTEC values used came from the GPS permanent stations belonging to the global IGS (International GNSS Service) network. We chose stations located at magnetic mid-latitudes. Moreover, three-longitude bands representing the ionospheric behavior at different local times (LT) were studied. Because the April 2000 storm has been extensively studied for many authors, the results are compared with those in the literature and we found a very good agreement as expected.En este trabajo perseguimos la idea de estimar un parámetro que nos permita calcular la respuesta ionosférica local a un evento geosférico desencadenante de una tormenta ionosférica. Para ello, se eligió la aplicación de la técnica ondeleta debido a su capacidad para analizar señales no estacionarias. La ventaja del método de análisis en tiempo y frecuencia llamada Transformada Ondeleta reside en el hecho de que provee información, no sólo acerca de las frecuencias del evento, sino también sobre su ubicación en la serie de tiempo. En concreto, se calcula el promedio por escalas de la potencia de la transformada ondeleta (SWAP, de su sigla en inglés Scale Average Wavelet Power) para dos parámetros que describen la respuesta local de la magnetosfera y la ionosfera a una tormenta. En particular, se propone el retraso de tiempo entre los valores máximos de SAWP aplicadas al vTEC (Contenido Electrónico Total en dirección Vertical) y la componente horizontal del campo geomagnético (H), como parámetros cuyas variaciones caracterizan el comportamiento local de la tormenta ionosférica. El parámetro propuesto se aplicó a las perturbaciones geomagnética e ionosférica causadas por una eyección de masa coronal (CME, Coronal Mass Ejection), que tuvo lugar el 4 de abril de 2000. Se utilizaron valores vTEC calculados a partir de las observaciones GPS y H en la superficie de la Tierra, medida en las estaciones cercanas a cada estación de GPS elegida. Los valores de vTEC utilizados provinieron de las estaciones GPS permanentes que pertenecen a la red del servicio internacional IGS (International GNSS Service). Entre todas, elegimos estaciones situadas en latitudes magnéticas medias. Por otra parte, estudiamos tres bandas de longitud que representan el comportamiento de la ionosfera a distintas horas locales (LT). Debido a que la tormenta de abril de 2000 ha sido ampliamente estudiada por muchos autores, los resultados se comparan con los de la literatura y nos encontramos con un muy buen acuerdo entre los datos publicados y nuestros resultados, tal y como se esperaba.Fil: Fernandez, Laura Isabel. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Meza, Amalia Margarita. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas; ArgentinaFil: Van Zele, Maria Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ciencias Geológicas; Argentin

Recent advances in low-temperature deposition methods of transparent, photocatalytic TiO2 coatings on polymers

In this paper, we present an overview as well as current advances in the low-temperature deposition of highly crystalline suspensions of titania nanoparticles on polymers for photocatalytic applications. The presence of preformed titania nanoparticles yields the possibility of producing photocatalytically active coatings at reduced temperatures. Transparent and photocatalytically active TiO2 coatings that degrade organic matter, have been widely applied to bestow self-cleaning properties onto surfaces. This low-temperature deposition method and its transition to polymers would open an entire array of possible self-cleaning applications. During this research, incorporation of a silica buffer layer was applied to improve the compatibility of the inorganic coating on a substrate, such as polymethylmethacrylate (PMMA) and polyphenylsulphone (PPSU). The photocatalytic activity of the obtained coating was analyzed for its photocatalytic abilities by evaluating the color removal of a dye solution (methylene blue, MB) under UV irradiation and compared with commercial Pilkington Activ (R) self-cleaning glass. Our results indicate that the titania-coated silica-polymer systems yield a higher photocatalytic activity towards the degradation of organic pollutants. This method proves that the deposition of highly crystalline anatase suspensions on silica buffer layers is a viable method to produce photocatalytic coatings on heat-sensitive substrates

Chiropractors as Expert Medical Witnesses

This paper examines the rules of evidence concerning the admissibility of testimony of chiropractors as expert medical witnesses

The choice of the geomagnetically quiet days

Las variaciones geomagnéticamente tranquilas en latitudes bajas y medias son aquellas debidas al movimiento de iones y electrones en la región E ionosférica. Para el estudio de estas variaciones (Sq), de perturbaciones y de tormentas, es necesario identificar cuáles días pueden considerarse tranquilos. El objetivo del trabajo es poner en evidencia la presencia de variaciones debidas a diferentes causas en algunos de los 5 días más tranquilos de un mes (aún con el mismo nivel de perturbación geomagnética) y mostrar que la identificación de esos días (Q) es conveniente hacerla para cada caso en particular.Quiet geomagnetic variations in low and middle latitudes are those due to the movement of ions and electrons in the ionospheric E region. To study these variations (Sq), disturbances and storms, it is necessary to identify which days may be considered as quiet. The aim of this work is to demonstrate the presence of variations due to different causes in some of the 5 quietest days a month (even with the same level of geomagnetic disturbance) and show that the identification of those days (Q) should be made for each particular case.Fil: Van Zele, Maria Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Geociencias Basicas, Aplicadas y Ambientales de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Geociencias Basicas, Aplicadas y Ambientales de Buenos Aires; Argentin

DESIGN OF SUBSTRATE INTEGRATED WAVEGUIDE H- PLANE HORN ANTENNA ON A PTFE SUBSTRATE

Rectangular dielectric loaded substrate integrated waveguide (SIW) H-plane horn antenna, operating at 26 GHz has been proposed in this paper. For the simulations, a substrate of thickness 3.2mm and a dielectric material of Poly Tetra Fluoro Ethylene (PTFE) has been used. The size of antenna was reduced and a dielectric slab was loaded in front of the horn. This resulted in the increase of gain and also narrow beamwidths in the E- plane and H- plane. A comparison between two horn antennas, one without dielectric loading and one with dielectric loading has been presented in this paper

Quiet solar geomagnetic variations at observatories in symmetrical latitudes during a minimum of solar activity

Solar geomagnetic variations on quiet days (Sq), neglecting the small lunar contribution (L), are compared for Teoloyucan (geogr.lal 19°45', long. -99° 11') and La Quiaca (geogr.lat -22°06', long.-65°36’), located in the longitudinal sector of maximum difference between geographic and geomagnetic latitudes, the latter being 29,6° and -10,6°respectively. Given the manifest asymmetry, even during the equinoxes comparable data from Pilar (geogr.lat-31°40', long.-63°53'; geomagn.lat-20,40) are supplied. Noon values of the geomagnetic north component of Sq can be represented by a plane model including an electrojet centered al the dip equator and two ionospheric current systems of greater latitudinal extent Application of this model to the particular group of E-months (March/April-September/October) shows that the distance between the vortices of these current systems and the equator is greater in the northern hemisphere than in the southern. Merely geomagnetic causes cannot account for this discrepancy.El objetivo del trabajo es comparar las variaciones geomagnéticas diarias solares tranquilas (Sq), despreciando cualquier influencia lunar, de los observatorios Teoloyucan (lat. geog 19°45', long. geog.-99°l 1') y La Quiaca (lat. geog. -22°6', long. geog.- 65°36') en los que es máxima la diferencia entre la latitud geomagnética (29,6° el primero,-10,6° el segundo) y la geográfica. Dada la asimetría manifiesta aún durante los equinoccios, se comparan las variaciones con las obtenidas en el observatorio Pilar (lat. geog.-31°40’, long. geog-63°53', lat. geom.-20,4°). Ajustando los valores de mediodía de la componente geomagnética norte de Sq a un modelo plano constituido por un electrochorro centrado en el ecuador de inclinación y dos sistemas de corrientes ionosféricas más extendidos en latitud se halla que la distancia entre el ecuador y el vórtice de esos sistemas como así también la intensidad de la corriente ionosférica total durante los meses marzo-abril-setiembre-octubre son mayores en el hemisferio norte que en el austral.Material digitalizado en SEDICI gracias a la colaboración de la Facultad de Ciencias Astronómicas y Geofísicas (UNLP).Asociación Argentina de Geofísicos y Geodesta

Analysis of a Permo-Triassic polarity transition in different absolute reconstructions of Pangaea, considering a model with features of the present Earth magnetic field

The main objective of this paper is to show that the distribution of transitional palaeomagnetic data recorded at 250 Ma are in agreement with simulated data that depend on the sampling site, using a model that considers features of the Present Earth magnetic field. The analysis was performed comparing simulated reversals with the Permo-Triassic polarity transition recorded in the Siberian Trap Basalts. The palaeomagnetic data were corrected according to the Palaeo-latitude and Palaeo-longitude of Siberia (absolute reconstruction) at 250 Ma using hotspot tracks. To obtain the motion of Siberia relative to hotspots from the Present time back to 250 Ma, three different Pangaea models were considered (Pangaea A, Pangaea A2, Pangaea B). In spite of the uncertainties associated with the use of hotspot frameworks and Pangaea configurations, both the modelled and recorded data show a remarkable fit when absolute reconstructions of Pangaea A and A2 configurations are performed. The agreement between both simulated and recorded data suggests that similar features to that of the Present Earth magnetic field could have been involved in reversals since the Permo-Triassic

Leren met simulatieprogramma's: kwantum tunneling modelleren in het practicum natuurkunde

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Twelve-year follow-up study after endoscopic sinus surgery in patients with chronic rhinosinusitis with nasal polyposis

Abstract Background Chronic rhinosinusitis with nasal polyposis (CRSwNP) is a therapeutic challenge because of the high recurrence rate. Surgical intervention should be considered in patients who fail to improve after medical treatment. We monitored recurrence and revision surgery over 12 years after endoscopic sinus surgery in CRSwNP patients. Methods In this prospective cohort study, 47 patients with CRSwNP, who underwent primary or revision extended endoscopic sinus surgery, were followed. Clinical symptoms and total nasal endoscopic polyp score were evaluated before, 6 years and 12 years after surgery. Results Twelve years after surgery, 38 out of 47 patients (80.9%) were available for examination. There still was a significantly better symptom score and total nasal endoscopic polyp score compared to before surgery (P < 0.001). Within the 12-year follow-up period, 30 out of 38 patients developed recurrent nasal polyps, of which 14 patients underwent additional revision surgery. Comorbid allergic sensitization and tissue IL-5 levels were found to be significant predictors for the need of revision surgery. Conclusions This long-term cohort study, investigating the outcome after surgery in CRSwNP, showed that, despite the low number of patients, 78.9% of patients with CRSwNP were subject to recurrence of the disease and 36.8% to revision surgery over a 12-year period