Residual stress distribution in ferritic-austenitic steel joints made by laser welding

The present investigation addresse the influence of laser welding process-ing parameters used for joining dis-similar metals (ferritic to austenitic steel), on the induced residual stress field. Welding was performed on a Nd:YAG laser DY033 (3300 W) in a continuous wave (CW), keyhole mode. The base metals (BM) employed in this study are AISI 1010 carbon steel (CS) and AISI 304L austenitic stainless steel (SS). Pairs of dissimilar plates of 200 mm x 45 mm x 3 mm were butt joined by laser welding. Different sets of parameters were used to engineer the base metals apportionment at joint formation, namely distinct dilution rates. Residual strain scanning, carried out by neutron diffraction was used to assess the joints. Through-thickness residual stress maps were determined for the laser welded samples of dis-similar steels using high spatial reso-lution. As a result, an appropriate set of processing parameters, able to mi-nimize the local tensile residual stress associated to the welding process, was found.

Dynamic response of a monolithic master-oscillator power-amplifier at 1.5 ��m

We study experimentally the dynamic properties of a fully integrated high power master-oscillator power-amplifier emitting at 1.5 ��m under continuous wave and gain-switching conditions. High peak power (2.7 W) optical pulses with short duration (~ 110 ps) have been generated by gain switching the master-oscillator. We show the existence of working points at very close driving conditions with stable or unstable regimes caused by the compound cavity effects. The optical and radio-frequency spectra of stable and unstable operating points are analyzed.

Lidar uncertainty in complex terrain development of a bias correction methodology

El autor ha trabajado como parte del equipo de investigaci��n en mediciones de viento en el Centro Nacional de Energ��as Renovables (CENER), Espa��a, en cooperaci��n con la Universidad Polit��cnica de Madrid y la Universidad T��cnica de Dinamarca. El presente reporte recapitula el trabajo de investigaci��n realizado durante los ��ltimos 4.5 a��os en el estudio de las fuentes de error de los sistemas de medici��n remota de viento, basados en la tecnolog��a lidar, enfocado al error causado por los efectos del terreno complejo. Este trabajo corresponde a una tarea del paquete de trabajo dedicado al estudio de sistemas remotos de medici��n de viento, perteneciente al proyecto de intestigaci��n europeo del 7mo programa marco WAUDIT. Adicionalmente, los datos de viento reales han sido obtenidos durante las campa��as de medici��n en terreno llano y terreno complejo, pertenecientes al tambi��n proyecto de intestigaci��n europeo del 7mo programa marco SAFEWIND. El principal objetivo de este trabajo de investigaci��n es determinar los efectos del terreno complejo en el error de medici��n de la velocidad del viento obtenida con los sistemas de medici��n remota lidar. Con este conocimiento, es posible proponer una metodolog��a de correcci��n del error de las mediciones del lidar. Esta metodolog��a est�� basada en la estimaci��n de las variaciones del campo de viento no uniforme dentro del volumen de medici��n del lidar. Las variaciones promedio del campo de viento son predichas a partir de los resultados de las simulaciones computacionales de viento RANS, realizadas para el parque experimental de Alaiz. La metodolog��a de correcci��n es verificada con los resultados de las simulaciones RANS y validadas con las mediciones reales adquiridas en la campa��a de medici��n en terreno complejo. Al inicio de este reporte, el marco te��rico describiendo el principio de medici��n de la tecnolog��a lidar utilizada, es presentado con el fin de familiarizar al lector con los principales conceptos a utilizar a lo largo de este trabajo. Posteriormente, el estado del arte es presentado en donde se describe los avances realizados en el desarrollo de la la tecnolog��a lidar aplicados al sector de la energ��a e��lica. En la parte experimental de este trabajo de investigaci��n se ha estudiado los datos adquiridos durante las dos campa��as de medici��n realizadas. Estas campa��as has sido realizadas en terreno llano y complejo, con el fin de complementar los conocimiento adquiridos en casa una de ellas y poder comparar los efectos del terreno en las mediciones de viento realizadas con sistemas remotos lidar. La primer campa��a experimental se desarrollo en terreno llano, en el parque de ensayos de aerogeneradores H0vs0re, propiedad de DTU Wind Energy (anteriormente Ris0). La segunda campa��a experimental se llev�� a cabo en el parque de ensayos de aerogeneradores Alaiz, propiedad de CENER. Exactamente los mismos dos equipos lidar fueron utilizados en estas campa��as, haciendo de estos experimentos altamente relevantes en el contexto de evaluaci��n del recurso e��lico. Un equipo lidar est�� basado en tecnolog��a de onda continua, mientras que el otro est�� basado en tecnolog��a de onda pulsada. La velocidad del viento fue medida, adem��s de con los equipos lidar, con anem��metros de cazoletas, veletas y anem��metros verticales, instalados en m��stiles meteorol��gicos. Los sensores del m��stil meteorol��gico son considerados como las mediciones de referencia en el presente estudio. En primera instancia, se han analizado los promedios diez min��tales de las medidas de viento. El objetivo es identificar las principales fuentes de error en las mediciones de los equipos lidar causadas por diferentes condiciones atmosf��ricas y por el flujo no uniforme de viento causado por el terreno complejo. El error del lidar ha sido estudiado como funci��n de varias propiedades estad��sticas del viento, como lo son el ��ngulo vertical de inclinaci��n, la intensidad de turbulencia, la velocidad vertical, la estabilidad atmosf��rica y las caracter��sticas del terreno. El prop��sito es usar este conocimiento con el fin de definir criterios de filtrado de datos. Seguidamente, se propone una metodolog��a para corregir el error del lidar causado por el campo de viento no uniforme, producido por la presencia de terreno complejo. Esta metodolog��a est�� basada en el an��lisis matem��tico inicial sobre el proceso de c��lculo de la velocidad de viento por los equipos lidar de onda continua. La metodolog��a de correcci��n propuesta hace uso de las variaciones de viento calculadas a partir de las simulaciones RANS realizadas para el parque experimental de Alaiz. Una ventaja importante que presenta esta metodolog��a es que las propiedades el campo de viento real, presentes en las mediciones instant��neas del lidar de onda continua, puede dar paso a an��lisis adicionales como parte del trabajo a futuro. Dentro del marco del proyecto, el trabajo diario se realiz�� en las instalaciones de CENER, con supervisi��n cercana de la UPM, incluyendo una estancia de 1.5 meses en la universidad. Durante esta estancia, se defini�� el an��lisis matem��tico de las mediciones de viento realizadas por el equipo lidar de onda continua. Adicionalmente, los efectos del campo de viento no uniforme sobre el error de medici��n del lidar fueron anal��ticamente definidos, despu��s de asumir algunas simplificaciones. Adicionalmente, durante la etapa inicial de este proyecto se desarrollo una importante trabajo de cooperaci��n con DTU Wind Energy. Gracias a esto, el autor realiz�� una estancia de 1.5 meses en Dinamarca. Durante esta estancia, el autor realiz�� una visita a la campa��a de medici��n en terreno llano con el fin de aprender los aspectos b��sicos del dise��o de campa��as de medidas experimentales, el estudio del terreno y los alrededores y familiarizarse con la instrumentaci��n del m��stil meteorol��gico, el sistema de adquisici��n y almacenamiento de datos, as�� como de el estudio y reporte del an��lisis de mediciones. ABSTRACT The present report summarizes the research work performed during last 4.5 years of investigation on the sources of lidar bias due to complex terrain. This work corresponds to one task of the remote sensing work package, belonging to the FP7 WAUDIT project. Furthermore, the field data from the wind velocity measurement campaigns of the FP7 SafeWind project have been used in this report. The main objective of this research work is to determine the terrain effects on the lidar bias in the measured wind velocity. With this knowledge, it is possible to propose a lidar bias correction methodology. This methodology is based on an estimation of the wind field variations within the lidar scan volume. The wind field variations are calculated from RANS simulations performed from the Alaiz test site. The methodology is validated against real scale measurements recorded during an eight month measurement campaign at the Alaiz test site. Firstly, the mathematical framework of the lidar sensing principle is introduced and an overview of the state of the art is presented. The experimental part includes the study of two different, but complementary experiments. The first experiment was a measurement campaign performed in flat terrain, at DTU Wind Energy H0vs0re test site, while the second experiment was performed in complex terrain at CENER Alaiz test site. Exactly the same two lidar devices, based on continuous wave and pulsed wave systems, have been used in the two consecutive measurement campaigns, making this a relevant experiment in the context of wind resource assessment. The wind velocity was sensed by the lidars and standard cup anemometry and wind vanes (installed on a met mast). The met mast sensors are considered as the reference wind velocity measurements. The first analysis of the experimental data is dedicated to identify the main sources of lidar bias present in the 10 minute average values. The purpose is to identify the bias magnitude introduced by different atmospheric conditions and by the non-uniform wind flow resultant of the terrain irregularities. The lidar bias as function of several statistical properties of the wind flow like the tilt angle, turbulence intensity, vertical velocity, atmospheric stability and the terrain characteristics have been studied. The aim of this exercise is to use this knowledge in order to define useful lidar bias data filters. Then, a methodology to correct the lidar bias caused by non-uniform wind flow is proposed, based on the initial mathematical analysis of the lidar measurements. The proposed lidar bias correction methodology has been developed focusing on the the continuous wave lidar system. In a last step, the proposed lidar bias correction methodology is validated with the data of the complex terrain measurement campaign. The methodology makes use of the wind field variations obtained from the RANS analysis. The results are presented and discussed. The advantage of this methodology is that the wind field properties at the Alaiz test site can be studied with more detail, based on the instantaneous measurements of the CW lidar. Within the project framework, the daily basis work has been done at CENER, with close guidance and support from the UPM, including an exchange period of 1.5 months. During this exchange period, the mathematical analysis of the lidar sensing of the wind velocity was defined. Furthermore, the effects of non-uniform wind fields on the lidar bias were analytically defined, after making some assumptions for the sake of simplification. Moreover, there has been an important cooperation with DTU Wind Energy, where a secondment period of 1.5 months has been done as well. During the secondment period at DTU Wind Energy, an important introductory learning has taken place. The learned aspects include the design of an experimental measurement campaign in flat terrain, the site assessment study of obstacles and terrain conditions, the data acquisition and processing, as well as the study and reporting of the measurement analysis.

Propiedades ��pticas de los Materiales Activos en Diodos L��ser con Confinamiento Cu��ntico

En esta tesis se recoge el trabajo experimental realizado para la caracterizaci��n de las propiedades ��pticas en diodos l��ser construidos con estructuras basadas en pozos cu��nticos (QW) y puntos cu��nticos (QD). Las propiedades que se han estudiado en estos dispositivos son los espectros de ganancia, ganancia diferencial, ��ndice diferencial y factor de ensanchamiento de l��nea (LEF). La comprensi��n de estas propiedades es de especial importancia para el dise��o de nuevos diodos l��ser destinados a ser utilizados en aplicaciones exigentes como son las comunicaciones ��pticas o aplicaciones m��dicas. El estudio se ha llevado a cabo en muestras de diodos l��ser suministrados por diferentes fabricantes: Ferdinand Braun Institut f��r H��chstfrequenztechnik, Thales Research and Technology y la Universidad de W��rzburg. Debido a esto las muestras de los l��seres se han suministrado en diferentes configuraciones, utiliz��ndose tanto dispositivos con cavidades de ��rea ancha como de tipo caballete (���ridge���). En los trabajos se ha realizado el dise��o y la construcci��n de los montajes experimentales y la implementaci��n de los m��todos anal��ticos necesarios para el estudio de las diferentes muestras. En los montajes experimentales se han implementado procesos para el filtrado espacial de los modos laterales de la cavidad presentes en los l��seres de ��rea ancha. Los m��todos anal��ticos implementados se han utilizado para reducir los errores existentes en los sistemas de medida, mejorar su precisi��n y para separar la variaci��n de ��ndice en debida al calentamiento y la variaci��n de corriente cuando los l��seres operan en continua. El estudio sistem��tico de las propiedades de ��pticas de los diodos l��ser basados en QW y QD ha permitido concluir que propiedades como el factor de ensanchamiento de l��nea no tienen por qu�� ser necesariamente inferiores en estos ��ltimos, ya que dependen de las condiciones de inyecci��n. En los l��seres de QW se ha observado experimentalmente una reducci��n del factor de ensanchamiento de l��nea al alcanzarse la segunda transici��n, debido al aumento de la ganancia diferencial. ABSTRACT This thesis includes the experimental work for the characterization of optical properties of quantum well (QW) and quantum dot (QD) laser diodes. The properties that have been studied in these devices are the gain, differential gain, differential index and the linewith enhancement factor (LEF). The understating of these properties is of special importance for the design of new laser diodes to be used in exigent applications such as optical communications or medical applications. The study has been carried out using laser samples supplied by different manufacturers: Ferdinand Braun Institut fu��r H��ochstfrequenztechnik, Thales Research and Technology and the University of Wu��rzburg. Because of this the laser samples were supplied in various configurations, using both broad area and ridge devices. In the work it has been done the design and construction of the experimental setups and implementation of analytical methods required for the study of the different devices. In the experimental set-ups it has been implemented a spatial filtering process to remove the lateral modes present in broad area lasers. The implemented analytical methods has been used to reduce the experimental errors in the measurement systems, improve the accuracy and separate the index variation caused by heating and current variation when the lasers operated on continuous wave. The systematic study of the optical properties of the QW and QD laser diodes has allowed concluding that properties such the linewith enhancement factor does not have to be necessary to be lower in the QD devices, since it is dependent on the injections conditions. In this work it has been experimentally observed a reduction of the linewith enhancement factor where the second transition has been reached mainly due to in the increased of the differential gain which is observed in this situation.

High-brightness all semiconductor laser at 1.57 ��m for space-borne lidar measurements of atmospheric carbon dioxide: device design and analysis of requirements

The availability of suitable laser sources is one of the main challenges in future space missions for accurate measurement of atmospheric CO2. The main objective of the European project BRITESPACE is to demonstrate the feasibility of an all-semiconductor laser source to be used as a space-borne laser transmitter in an Integrated Path Differential Absorption (IPDA) lidar system. We present here the proposed transmitter and system architectures, the initial device design and the results of the simulations performed in order to estimate the source requirements in terms of power, beam quality, and spectral properties to achieve the required measurement accuracy. The laser transmitter is based on two InGaAsP/InP monolithic Master Oscillator Power Amplifiers (MOPAs), providing the ON and OFF wavelengths close to the selected absorption line around 1.57 ��m. Each MOPA consists of a frequency stabilized Distributed Feedback (DFB) master oscillator, a modulator section, and a tapered semiconductor amplifier optimized to maximize the optical output power. The design of the space-compliant laser module includes the beam forming optics and the thermoelectric coolers.The proposed system replaces the conventional pulsed source with a modulated continuous wave source using the Random Modulation-Continuous Wave (RM-CW) approach, allowing the designed semiconductor MOPA to be applicable in such applications. The system requirements for obtaining a CO2 retrieval accuracy of 1 ppmv and a spatial resolution of less than 10 meters have been defined. Envelope estimated of the returns indicate that the average power needed is of a few watts and that the main noise source is the ambient noise.

High brightness semiconductor lasers as transmitters for space lidar systems

High brightness semiconductor lasers are potential transmitters for future space lidar systems. In the framework of the European Project BRITESPACE, we propose an all-semiconductor laser source for an Integrated Path Differential Absorption lidar system for column-averaged measurements of atmospheric CO2 in future satellite missions. The complete system architecture has to be adapted to the particular emission properties of these devices using a Random Modulated Continuous Wave approach. We present the initial experimental results of the InGaAsP/InP monolithic Master Oscillator Power Amplifiers, providing the ON and OFF wavelengths close to the selected absorption line around 1572 nm.

Modelado de un sistema de telemetr��a LIDAR CW-RM

Los sistemas LIDAR (Light Detection and Ranging) permiten medir la distancia entre dos puntos, evaluando el tiempo que tarda una se��al ��ptica (generalmente procedente de un L��ser) en hacer un recorrido de ida y vuelta entre dichos puntos. En los sistemas CW-RM (Continuous Wave - Random Modulated) esta evaluaci��n se hace calculando la correlaci��n entre la se��al emitida (pseudoaleatoria) y la recibida (cuyo retardo depender de la distancia entre los puntos). Este sistema CW-RM tiene la ventaja sobre los TOF (Time Of Flight) de que funcionan bien ��n con se��ales recibidas de reducida relaci��n se��al a ruido. La precisi��n de la medida, depende, entre otros par��metros, del tiempo de bit de la secuencia pseudoaleatoria y de la frecuencia de muestreo del sistema que capta las se��ales y posteriormente las correla. El objetivo del presente trabajo es realizar un sistema de gran precisi��n, utilizando se��ales pseudoaleatorias de tiempo de bit de centenas de pico segundo y frecuencia de muestreo de Gs/s, para lo que deberemos utilizar equipamiento disponible en laboratorio, as mismo deberemos seleccionar y con guiar los l��seres emisores para que puedan trabajar a estas velocidades. La primera etapa del proyecto ser�� el conocimiento del instrumental de laboratorio que vamos a utilizar en el set-up. La segunda etapa ser�� la realizaci��n de un primer montaje en el que se conectar�� emisor y receptor a trav��s de una fibra ��ptica de longitud conocida. Esto nos permitir �� el desarrollo de algoritmos para extraer informaci��n de la medida y para una calibraci��n del instrumental para posteriores medidas. La tercera etapa es el dise��o definitivo con emisor al aire para el que tendremos que ajustar todos los elementos ��pticos del sistema, de modo que se pueda detectar la luz reflejada y adem��s se pueda reducir parte de la luz de background.

Estudio del estado de la vegetaci��n de ribera en la Espa��a peninsular. Implicaciones de la alteraci��n hidrol��gica y herramientas para su manejo y gesti��n

El objetivo general de este trabajo es explorar las potenciales interacciones entre la alteraci��n hidrol��gica y el estado de la vegetaci��n de ribera en diversas cuencas hidrogr��ficas espa��olas. La mayor parte del ��rea de estudio est�� dentro de la regi��n Mediterr��nea, una regi��n caracterizada por un particular comportamiento climatol��gico, ecol��gico y socio-econ��mico. Las cuencas estudiadas son: Guadiana, Guadalquivir, Tajo, y Duero. Para complementar el estudio y comparar resultados con otras regiones clim��ticas espa��olas se estudiaron dos Demarcaciones atl��nticas: Cant��brico y Mi��o-Sil. El funcionamiento fluvial, en las ��reas mediterr��neas, presenta grandes variaciones en el r��gimen h��drico, siendo uno de los principales controladores de la estructura, composici��n y distribuci��n de la vegetaci��n de ribera. Para investigar las interacciones mencionadas previamente, se presenta un nuevo ��ndice, Riparian Forest Evaluation (RFV). El objetivo de este ��ndice es valorar el estado de la vegetaci��n de ribera en base a los principales controladores hidro-morfol��gicos responsables de la din��mica fluvial, y por tanto, relacionados con el desarrollo del corredor ribere��o. RFV divide la evaluaci��n del bosque de ribera en cuatro componentes: continuidad longitudinal, transversal, y vertical (dimensiones espaciales), y condiciones del regenerado (dimensi��n temporal). La clasificaci��n final est�� basada en las mismas cinco clases fijadas por la Directiva europea Marco del Agua (DMA) (2000/60/CE) para valorar el estado ecol��gico de las masas de agua. La aplicaci��n de este ��ndice en 187 masas de agua ha mostrado su facilidad de aplicaci��n y su consistencia desde un punto de vista legislativo y t��cnicocient��fico. En paralelo al dise��o del ��ndice RFV, se ha desarrollado una nueva herramienta para dar apoyo a la evaluaci��n del bosque de ribera (RFV) y la extracci��n de variables hidromorfol��gicas a escala de masa de agua en lugar de a escala local (muestreo de campo local). Se trata de Riparian Characterisation by LiDAR (RiC-DAR), que permite valorar el estado del bosque de ribera de una manera semiautom��tica, en un modo cuasi-continuo, usando LiDAR de alta resoluci��n. Esto hecho permite mejorar significativamente la calidad y cantidad de informaci��n comparado con la toma de datos en campo, lo que permite reducir los recursos, particularmente cuando se trabaja a escala de masas de agua. Una de las potenciales causas de la degradaci��n del bosque de ribera es la alteraci��n hidrol��gica; as�� una vez se ha realizado la evaluaci��n del bosque de ribera basada en elementos hidro-morfol��gicos ligados al r��gimen h��drico (RFV), se han identificado las potenciales relaciones entre la alteraci��n hidrol��gica y la degradaci��n de la vegetaci��n riparia. Para ello, se requiere contar con series de aforos fiables y de una duraci��n apropiada. Para satisfacer este requerimiento, se ha creado una nueva herramienta: el Servidor de Datos para el Estudio de la Alteraci��n Hidrol��gica (SEDAH). Esta herramienta genera datos diarios y mensuales completados para m��s a��os, construyendo as�� bases de datos m��s aptas para el estudio de la alteraci��n hidrol��gica. (http://ambiental.cedex.es/Sedah) Haciendo uso de las herramientas y m��todos desarrollados previamente, se han calculado diferentes indicadores de alteraci��n hidrol��gica en 87 masas de agua que han sido analizados conjuntamente con el estado de la vegetaci��n de ribera. Los resultados estad��sticos han mostrado relaciones significativas entre ellos: la degradaci��n de la vegetaci��n podr��a estar fuertemente ligada a la alteraci��n del r��gimen h��drico en a��os secos y a las sequ��as en el entorno mediterr��neo. A su vez se ha analizado la relaci��n del estado del bosque de ribera con el estado ecol��gico basado en la DMA, mostrando una relaci��n no significativa. Esta y otras potenciales relaciones son discutidas a lo largo del documento. Los resultados permiten proponer recomendaciones de gesti��n de la vegetaci��n de ribera y de manejo del r��gimen de caudales para masas de agua reguladas. ABSTRACT The general objective of this work is to explore the potential interactions between hydrologic alteration and degradation of the riparian vegetation, mainly focused in the Mediterranean Environment. The majority of the study area is part of the Spanish Mediterranean region, a geographical environment characterized by a singular climatologic, ecological and socio-economical behavior. The basins analysed in this work are: Guadiana, Guadalquivir, Tagus, Douro. In order to complete the results and compare those to other climatic regions in Spain, two Atlantic Districts where selected: Cant��brico and Mi��o-Sil. The river functioning, in the Mediterranean areas, presents great variations in the flow regimes being one of the main drivers of the riparian vegetation development. To explore the interactions stated above, a new index is presented, Riparian Forest Evaluation (RFV). This index is aimed to assess the status of the riparian vegetation based on the main hydromorphological drivers responsible of the river dynamic, and so, related to the development of the riparian corridor. RFV split the evaluation of the riparian forest into four components: longitudinal continuity, transversal continuity, vertical (structure) continuity and regeneration (temporal) continuity. The final classification is based in the same five classes to those stated in the European Water Frame Work directive to assess the ecological status. The application of this index over 187 water bodies has shown to be easily applicable and consistent from a regulatory perspective. In parallel to the design of RFV, a new tool has been developed to enhance the evaluation of the riparian forest and river morphology (RFV and morphological parameters) at water body scale rather than at local scale, i.e. when field surveyed at different sites. The Riparian Characterisation by LiDAR, RiC-DAR allows to assess the status of the riparian vegetation semi-automatically in a quasi-continuous way using high resolution LiDAR. This improves significantly the quantity and quality of information gathered through field sampling methods, reducing resources when working at larger scales. One of the potential major causes of degradation of the riparian forest is the hydrologic alteration; hence, once the evaluation of the riparian forest is done consistently based on hydro-morphological features linked to the hydrological regime (RVF), this work has identified potential relationships between hydrologic alteration and degradation of riparian vegetation. In order to do this, it is required to count with reliable series of flow records describing both reference and altered regimes. To satisfy this need, a new tool has been created, SEDAH, data server for assessing hydrologic alteration. This tool has completed daily and monthly gaps in the flow series to build up an improved database to assess the hydrologic alteration. This application is available on line (http://ambiental.cedex.es). Making use of the tools and methods developed previously, this work uses these data to work out indicators of hydrologic alteration through 87 water bodies to be analysed against the riparian status. These indicators are statistically analysed exploring significant relationships with the status of riparian vegetation and ecological status, showing some potential significant relationships; hence it seems that the degradation of riparian vegetation, particularly the regeneration, is associated with the alteration of the hydrologic regimen in dry years and draughts in Mediterranean environments. Furthermore, the analysis of the status of the ecological status and the status of the riparian vegetation has shown the lack of significant influence of the riparian vegetation in the final ecological status using the WFD approach applied in Spain. This and other potential relationships are discussed in this work. The results allow giving guidance on the management of both riparian vegetation and environmental flows of water bodies affected by flow regulation.

Chromophore-assisted light inactivation and self-organization of microtubules and motors

Chromophore-assisted light inactivation (CALI) offers the only method capable of modulating specific protein activities in localized regions and at particular times. Here, we generalize CALI so that it can be applied to a wider range of tasks. Specifically, we show that CALI can work with a genetically inserted epitope tag; we investigate the effectiveness of alternative dyes, especially fluorescein, comparing them with the standard CALI dye, malachite green; and we study the relative efficiencies of pulsed and continuous-wave illumination. We then use fluorescein-labeled hemagglutinin antibody fragments, together with relatively low-power continuous-wave illumination to examine the effectiveness of CALI targeted to kinesin. We show that CALI can destroy kinesin activity in at least two ways: it can either result in the apparent loss of motor activity, or it can cause irreversible attachment of the kinesin enzyme to its microtubule substrate. Finally, we apply this implementation of CALI to an in vitro system of motor proteins and microtubules that is capable of self-organized aster formation. In this system, CALI can effectively perturb local structure formation by blocking or reducing the degree of aster formation in chosen regions of the sample, without influencing structure formation elsewhere.

Insulin Action on GLUT4 Traffic Visualized in Single 3T3-L1 Adipocytes by Using Ultra-fast MicroscopyV���

A novel imaging technology, high-speed microscopy, has been used to visualize the process of GLUT4 translocation in response to insulin in single 3T3-L1 adipocytes. A key advantage of this technology is that it requires extremely low light exposure times, allowing the quasi-continuous capture of information over 20���30 min without photobleaching or photodamage. The half-time for the accumulation of GLUT4-eGFP (enhanced green fluorescent protein) at the plasma membrane in a single cell was found to be of 5���7 min at 37��C. This half-time is substantially longer than that of exocytic vesicle fusion in neuroendocrine cells, suggesting that additional regulatory mechanisms are involved in the stimulation of GLUT4 translocation by insulin. Analysis of four-dimensional images (3-D over time) revealed that, in response to insulin, GLUT4-eGFP-enriched vesicles rapidly travel from the juxtanuclear region to the plasma membrane. In nontransfected adipocytes, impairment of microtubule and actin filament function inhibited insulin-stimulated glucose transport by 70 and 50%, respectively. When both filament systems were impaired insulin-stimulated glucose transport was completely inhibited. Taken together, the data suggest that the regulation of long-range motility of GLUT4-containing vesicles through the interaction with microtubule- and actin-based cytoskeletal networks plays an important role in the overall effect of insulin on GLUT4 translocation.

Rapid Scan Electron Paramagnetic Resonance (EPR) and Digital EPR Development

Rapid scan electron paramagnetic resonance (EPR) was developed in the Eaton laboratory at the University of Denver. Applications of rapid scan to wider spectra, such as for immobilized nitroxides, spin-labeled proteins, irradiated tooth and fingernail samples were demonstrated in this dissertation. The scan width has been increased from 55 G to 160 G. The signal to noise (S/N) improvement for slowly tumbling spin-labeled protein samples that is provided by rapid scan EPR will be highly advantageous for biophysical studies. With substantial improvement in S/N by rapid scan, the dose estimation for irradiated tooth enamels became more reliable than the traditional continuous wave (CW) EPR. An alternate approach of rapid scan, called field-stepped direct detection EPR, was developed to reconstruct wider EPR signals. A Mn2+ containing crystal was measured by field-stepped direct detection EPR, which had a spectrum more than 6000 G wide. Since the field-stepped direct detection extends the advantages of rapid scan to much wider scan ranges, this methodology has a great potential to replace the traditional CW EPR. With recent advances in digital electronics, a digital rapid scan spectrometer was built based on an arbitrary waveform generator (AWG), which can excite spins and detect EPR signals with a fully digital system. A near-baseband detection method was used to acquire the in-phase and quadrature signals in one physical channel. The signal was analyzed digitally to generate ideally orthogonal quadrature signals. A multiharmonic algorithm was developed that employed harmonics of the modulation frequencies acquired in the spectrometer transient mode. It was applied for signals with complicated lineshapes, and can simplify the selection of modulation amplitude. A digital saturation recovery system based on an AWG was built at X-band (9.6 GHz). To demonstrate performance of the system, the spin-lattice relaxation time of a fused quartz rod was measured at room temperature with fully digital excitation and detection.

(Table 2) Picked maximum velocities from 3 radars (RAY, SHK, and SUM), showing 10 explosions at Erebus volcano, Antarctica, and their respective directivity vectors

We used a novel system of three continuous wave Doppler radars to successfully record the directivity of i) Strombolian explosions from the active lava lake of Erebus volcano, Antarctica, ii) eruptions at Stromboli volcano, Italy, and iii) a man-made explosion in a quarry. Erebus volcano contains a convecting phonolite lava lake, presumably connected to a magma chamber at depth. It is one of the few open vent volcanoes that allow a direct observation of source processes during explosions. Its lava lake is the source of frequent violent Strombolian explosions, caused by large gas bubbles bursting at the lake surface. The exact mechanism of these bubble bursts is unclear, as is the mechanism of the creation of the infrasound signal accompanying the explosions. We use the Doppler radar data to calculate the directivity of Strombolian eruptions at Erebus. This allows us to derive information about the expected type of infrasound source pattern (i.e. the role of a dipole in addition to the monopole signature) and the physical structure of the volcano. We recorded 10 large explosions simultaneously with three radars, enabling us to calculate time series of 3D directivity vectors (i.e. effectively 4D), which describe the direction of preferred expansion of the gas bubble during an explosion. Such directivity information allows a comparison to dipole infrasound radiation patterns recorded during similar explosions only a few weeks later. Video observations of explosions support our interpretation of the measurements. We conclude that at Erebus, the directivity of explosions is mainly controlled by random processes. Since the geometry of the uppermost conduit is assumed to have a large effect on the directivity of explosions, the results suggest a largely symmetrical uppermost conduit with a vertical axis of symmetry. For infrasound recordings, a significant dipole signature can be expected in addition to the predominant monopole signature.

Raw data of SCADCP (self-contained Acoustic Doppler Current Profiler) from three moorings in the Eastern Weddell Sea, 2005-2008

The success of any efforts to determine the effects of climate change on marine ecosystems depends on understanding in the first instance the natural variations, which contemporarily occur on the interannual and shorter time scales. Here we present results on the environmental controls of zooplankton distribution patterns and behaviour in the eastern Weddell Sea, Southern Ocean. Zooplankton abundance and vertical migration are derived from the mean volume backscattering strength (MVBS) and the vertical velocity measured by moored acoustic Doppler current profilers (ADCPs), which were deployed simultaneously at 64��S, 66.5��S and 69��S along the Greenwich Meridian from February, 2005, until March, 2008. While these time series span a period of full three years they resolve hourly changes. A highly persistent behavioural pattern found at all three mooring locations is the synchronous diel vertical migration (DVM) of two distinct groups of zooplankton that migrate between a deep residence depth during daytime and a shallow depth during nighttime. The DVM was closely coupled to the astronomical daylight cycles. However, while the DVM was symmetric around local noon, the annual modulation of the DVM was clearly asymmetric around winter solstice or summer solstice, respectively, at all three mooring sites. DVM at our observation sites persisted throughout winter, even at the highest latitude exposed to the polar night. Since the magnitude as well as the relative rate of change of illumination is minimal at this time, we propose that the ultimate causes of DVM separated from the light-mediated proximal cue that coordinates it. In all three years, a marked change in the migration behaviour occurred in late spring (late October/early November), when DVM ceased. The complete suspension of DVM after early November is possibly caused by the combination of two factors: (1) increased availability of food in the surface mixed layer provided by the phytoplankton spring bloom, and (2) vanishing diurnal enhancement of the threat from visually oriented predators when the illumination is quasi-continuous during the polar and subpolar summer. Zooplankton abundance in the water column, estimated as the mean MVBS in the depth range 50-300 m, was highest end of summer and lowest mid to end winter on the average annual cycle. However, zooplankton abundance varied several-fold between years and between locations. Based on satellite and in situ data of chlorophyll and sea ice as well as on hydrographic measurements, the interannual and spatial variations of zooplankton mean abundance can be explained by differences in the magnitude of the phytoplankton spring bloom, which develops during the seasonal sea ice retreat. Whereas the vernal ice melt appears necessary to stimulate the blooming of phytoplankton, it is not the determinator of the blooms magnitude, its areal extent and duration. A possible explanation for the limitation of the phytoplankton bloom in some years is top-down control. We hypothesise that the phytoplankton spring development can be curbed by grazing when the zooplankton had attained high abundance by growth during the preceding summer.

No-switching quantum key distribution using broadband modulated coherent light

We realize an end-to-end no-switching quantum key distribution protocol using continuous-wave coherent light. We encode weak broadband Gaussian modulations onto the amplitude and phase quadratures of light beams. Our no-switching protocol achieves high secret key rate via a post-selection protocol that utilizes both quadrature information simultaneously. We establish a secret key rate of 25 Mbits/s for a lossless channel and 1 kbit/s for 90% channel loss, per 17 MHz of detected bandwidth, assuming individual Gaussian eavesdropping attacks. Since our scheme is truly broadband, it can potentially deliver orders of magnitude higher key rates by extending the encoding bandwidth with higher-end telecommunication technology.

Testing the reliability of a new ultrasonic cardiac output monitor, the USCOM, by using aortic flowprobes in anesthetized dogs

We have used an animal model to test the reliability of a new portable continuous-wave Doppler ultrasonic cardiac output monitor, the USCOM. In six anesthetized dogs, cardiac output was measured with a high-precision transit time ultrasonic flowprobe placed on the ascending aorta. The dogs' cardiac output was increased with a dopamine infusion (0-15 mug (.) kg(-1) (.) min(-1)). Simultaneous flowprobe and USCOM cardiac output measurements were made. Up to 64 pairs of readings were collected from each dog. Data were compared by using the Bland and Altman plot method and Lin's concordance correlation coefficient. A total of 319 sets of paired readings were collected. The mean (+/-SD) cardiac output was 2.62 +/- 1.04 L/min, and readings ranged from 0.79 to 5.73 L/min. The mean bias between the 2 sets of readings was -0.01 L/min, with limits of agreement (95% confidence intervals) of -0.34 to 0.31 L/min. This represents a 13% error. In five of six dogs, there was a high degree of concordance, or agreement, between the 2 methods, with coefficients >0.9. The USCOM provided reliable measurements of cardiac output over a wide range of values. Clinical trials are needed to validate the device in humans.