Analyse geomagnetischer Variationen in den Zentralen und Südlichen Anden

Title, Contents 1 1\. Introduction 5 2\. Methodical fundamentals 9 2.1. The physical model 10 2.2. Calculation of transfer functions 11 2.3. Analysis of transfer function tensors 13 3\. On the study areas 19 3.1. The Central Andes 19 3.2. The Southern Andes 29 4\. Field data analysis 33 4.1. Processing techniques 33 4.2. Application to the processed data 35 4.3. Combination of processed arrays 39 5\. Presentation of the processed data 41 5.1. Central Andes 41 5.2. Southern Andes 51 6\. 2-D inversion of inter-station transfer functions 55 6.1. General considerations ... 55 6.1.1. ... on the amount of information 55 6.1.2. ... on the uniqueness of inversion solutions 56 6.2. The inversion scheme of the employed program 57 6.3. Calculations of sensitivities 59 6.4. Synthetic examples 61 6.4.1. Model from Siripunvaraporn & Egbert 62 6.4.2. A very crude ANCORP resistivity model 64 6.4.3. Inversion of data with various references 66 7\. Isotropic 2-D modelling 71 7.1. The ocean effect 71 7.2. On the sensitivity and accuracy of the two polarizations 72 7.3. Central Andes 74 7.4. Southern Andes 82 8\. Anisotropic 2-D modelling of magnetic data from the Southern Andes 89 9\. Discussion and conclusions 97 10\. Summary 105 Acknowledgements 107 Bibliography 109 Appendix 119 A Calculation of forward responses in REBOCC 119 A.1. Solution of the induction problem 119 A.2. Calculation of field components 121 B Data and joint inversion responses 123 C Station runtimes 129 D Analysis of an instrumental test recording 132This study is concerned with the (re)analysis of long period electromagnetic variation data recorded between 1993 and 2000 during several field campaigns in the Central (~21°S) and Southern (~39°S) Andes to derive the spatial distribution of subsurface electrical conductivity at this active continental margin. Taking particular advantage of the simultaneity of the data, additional to local transfer functions also inter-station transfer functions have been calculated and analyzed in terms of a full array data analysis. From uniqueness theorems for 2-D inversion solutions of ideal local data sets, it is shown that also for magnetic inter-station data, the 2-D inversion problem has in principle an unique solution. The analysis of such geomagnetic perturbation data is rarely performed and modern inversion programs are all designed for the analysis of local transfer functions. Therefore a recently published 2-D inversion code for local data has been extended to the inversion of geomagnetic inter-station transfer functions. Synthetic modelling studies demonstrate that over laterally extended conductivity anomalies an investigation of horizontal perturbation data can resolve the vertical conductivity distribution and thus support an analysis of impedance data, which are more likely subject to distortion effects due to superficial heterogeneities. An inversion of data with various references is also possible, though most probably not equally effective. Since in the Central Andes not all inter-station data can be related to the same reference, the potential of such data analysis could not fully be exploited here. Inclusion of geomagnetic data in the modelling generally confirms the anomalies derived in previous analysis - a good conductor below the Chilean Precordillera and a vast zone of high conductivity below the Bolivian Altiplano -, but indicates laterally enhanced conductivities in the eastern part of the Altiplano, which is not reflected in inversions of impedance data alone. The conductive anomaly below the volcanic arc in the Southern Andes is comparably weak, and therefore horizontal perturbations are small, so that they can not give significantly more insight into the subsurface conductivity distribution than local data. However, magnetic data in South Chile have clear signature of a continental mid to lower crustal horizontal electrical anisotropy. The anisotropy strike is not well constrained, but clockwise oblique to the structural resp. morphological strike. One possible explanation for the proposed anisotropy are conductive magmatic dykes, which are oriented parallel to the direction of maximum horizontal stress, and not just confined to a narrow band below the volcanic arc.Die Arbeit beschäftigt sich mit der Analyse langperiodischer elektromagnetischer Felddaten aus den Zentralen (~21°S) und Südlichen (~39°S) Anden, die in den Jahren 1993 bis 2000 während mehrerer Messkampagnen aufgezeichnet wurden um den Parameter der elektrischen Leitfähigkeit innerhalb der Subduktionszone räumlich abzubilden. Unter besonderer Ausnutzung der Gleichzeitigkeit der Messungen wurden zusätzlich zu lokalen Übertragungsfunktionen auch magnetische inter-station Übertragungsfunktionen (Perturbationsdaten) bestimmt und analysiert. Ausgehend von Eindeutigkeitstheoremen für 2D-Inversionslösungen für lokale Daten wird gezeigt, dass auch für ideale magnetische Perturbationsdaten das 2D-Inversionsproblem nur eine Lösung hat. Eine Analyse von magnetischen Perturbationsdaten wird allgemein nur selten angewandt und moderne Analyseprogramme sind entsprechend nur für lokale Daten ausgelegt. Im Rahmen dieser Arbeit wurde deshalb ein vor kurzem veröffentlichtes 2D- Inversionsprogramm um die Inversion geomagnetischer Perturbationen erweitert. Modellstudien belegen, dass durch eine Analyse von horizontalen magnetischen Perturbationen über lateral ausgedehnten Leitfähigkeitsanomalien die vertikale Leitfähigkeitsstruktur aufgelöst werden kann, so dass eine Auswertung von lokalen Impedanzen, welche durch oberflächennahe Heterogenitäten oft stärker verzerrt sind, unterstützt werden kann. Auch Daten mit verschiedenen Referenzstationen können invertiert werden, allerdings mit kaum vergleichbarer Effizienz. Da in den Zentralen Anden nicht alle Perturbationsdaten auf eine gemeinsame Referenz bezogen werden können, kann das Potential einer solchen Analyse hier nicht voll ausgschöpft werden. Bei Miteinbeziehung von magnetischen Übertragungsfunktionen in die 2D-Modellierung werden die aus früheren Arbeiten abgeleiteten Leitfähigkeitsanomalien - ein guter Leiter unter der chilenischen Präkordillere, sowie eine ausgedehnte Zone erhöhter Leitfähigkeit unter dem bolivianischen Altiplano - prinzipiell bestätigt, mit dem Unterschied, dass lateral höhere Leitfähigkeiten unter dem östlichen Altiplano modelliert werden, worauf aus einer Analyse magnetotellurischer Impedanzen nicht geschlossen wurde. Die Leitfähigkeitsanomalie unter dem vulkanischen Bogen in den Südlichen Anden ist vergleichsweise moderat und die Perturbation des horizontalen Magnetfeldes entsprechend gering, so dass eine Analyse dieser Daten die Auswertung lokaler Impedanzen nicht wesentlich unterstützen kann. Jedoch enthalten magnetische Daten in Südchile klare Hinweise auf eine horizontale elektrische Anisotropie in der mittleren bis unteren kontinentalen Kruste mit einer gegen die strukturelle Streichrichtung im Uhrzeigersinn verdrehten Richtung der Anisotropie. Als mögliche Erklärung können leitfähige magmatische Dykes angesehen werden, die parallel zur Richtung der maximalen horizontalen Spannungsrichtung ausgerichtet und nicht nur auf ein schmales Band unter dem vulkanischen Bogen begrenzt sind

UV light–induced linear IgA dermatosis

Various exogenous factors (eg, drugs, dietary antigens, trauma, infections, radiographs, and UV radiation) are known to induce or aggravate skin diseases. UV radiation in particular is known to induce or aggravate the autoimmune bullous diseases of pemphigus foliaceus, pemphigus vulgaris, and bullous pemphigoid. Its role in linear IgA dermatosis, however, is not well recognized. We report the second case of linear IgA dermatosis induced by intense sun exposure in which blistering was induced by UVA radiation. Furthermore, a review of the literature on photoinduced autoimmune bullous diseases and the wavelengths responsible for the induction of blistering is presented and several proposed mechanisms of action for the blister induction, including release or unmasking of antigens, promotion of antibody fixation by UV radiation, and launching of an inflammatory process, are discussed. We conclude that linear IgA dermatosis should be added to the list of autoimmune bullous diseases induced and/or aggravated by UV radiation

Wound Teleconsultation in Patients with Chronic Leg Ulcers

Background: The treatment of chronic leg ulcers requires frequent assessments of local wound status and adjustment of therapy. The availability of reasonably priced photographic equipment and quick electronic transfer of high-quality digital images should make it possible that the assessment of wound status can be made by remote experts. Objective: This study examines the feasibility of using teledermatology for wound assessment and therapeutic suggestions for patients with chronic leg ulcers. Methods: One hundred ten chronic leg ulcers of different origins were examined in face-to-face consultations. The examining doctor assessed the wound, made therapeutic recommendations and took 1-4 photographs of the wound using a digital camera. The digital images and relevant clinical information were then transmitted via a web application to an expert in wound care, who provided an independent teledermatological assessment of wound status and therapeutic recommendations. Results: In our study, a high accordance between direct consultations and electronic consultations was found in the assessment of chronic leg ulcers, especially for important features like slough (concordance: 84.6%), necrosis (concordance: 98.2%) and granulation tissue formation (concordance: 76.4%). Furthermore, the teledermatologist generally felt confident in recommending further treatment strategies and in planning further wound assessments via the internet. Conclusions: Our results suggest that teledermatology offers great potential for the future in chronic wound care. By reducing the need to travel long distances to the hospital or to consult a physician with expertise in wound care, wound teleconsultation might lower health care costs and improve the quality of life for patients with chronic wounds, while still maintaining a high quality of wound care

Time-correlated single photon counting for simultaneous monitoring Of zinc oxide nanoparticles and NAD(P)H in intact and barrier-disrupted volunteer skin

There is a lack of relevant, non-animal alternatives for assessing exposure and toxicity of nanoparticle-containing cosmetics, e.g. sunscreens. Our goal was to evaluate timecorrelated single photon counting (TCSPC) for simultaneous monitoring of zinc oxide nanoparticles (ZnO-NP) and the metabolic state of volunteer skin

Nanoparticles and microparticles for skin drug delivery

Nanosystems such as microemulsions (ME) and nanoemulsions (NE) offer considerable opportunities for targeted drug delivery to and via the skin. ME and NE are stable colloidal systems composed of oil and water, stabilised by a mixture of surfactants and cosurfactants, that have received particular interest as topical skin delivery systems. There is considerable scope to manipulate the formulation components and characteristics to achieve optimal bioavailability and minimal skin irritancy. This includes the incorporation of established chemical penetration enhancers to fluidize the stratum corneum lipid bilayers, thus reducing the primary skin barrier and increasing permeation. This review discusses nanosystems with utility in skin delivery and focuses on the composition and characterization of ME and NE for topical and transdermal delivery. The mechanism of skin delivery across the stratum corneum and via hair follicles is reviewed with particular focus on the influence of formulation

Nanoparticles and microparticles for skin drug delivery

Skin is a widely used route of delivery for local and systemic drugs and is potentially a route for their delivery as nanoparticles. The skin provides a natural physical barrier against particle penetration, but there are opportunities to deliver therapeutic nanoparticles, especially in diseased skin and to the openings of hair follicles. Whilst nanoparticle drug delivery has been touted as an enabling technology, its potential in treating local skin and systemic diseases has yet to be realised. Most drug delivery particle technologies are based on lipid carriers, i.e. solid lipid nanoparticles and nanoemulsions of around 300 nm in diameter, which are now considered microparticles. Metal nanoparticles are now recognized for seemingly small drug-like characteristics, i.e. antimicrobial activity and skin cancer prevention. We present our unpublished clinical data on nanoparticle penetration and previously published reports that support the hypothesis that nanoparticles N10 nm in diameter are unlikely to penetrate through the stratum corneum into viable human skin but will accumulate in the hair follicle openings, especially after massage. However, significant uptake does occur after damage and in certain diseased skin. Current chemistry limits both atom by atom construction of complex particulates and delineating their molecular interactions within biological systems. In this review we discuss the skin as a nanoparticle barrier, recent work in the field of nanoparticle drug delivery to the skin, and future directions currently being explored.