Streams and terrestrial ecosystems are linked through allochthonous organic matter inputs from streamside vegetation. This allochthonous material makes up the energy base for forested aquatic food webs. Therefore, removal of riparian vegetation associated with agricultural land use affects stream ecosystem structure and function. The objectives of this study were to measure and compare allochthonous input and leaf breakdown rates along a gradient of agricultural land use in southern Appalachian streams. Study streams were placed into the following land use categories: forest and light, moderate, and heavy agriculture. Several physical, chemical, and biological parameters also were measured including discharge, temperature, nutrient concentrations, macroinvertebrate abundance and density, periphyton biomass, and chlorophyll a concentration. In forested, light agricultural, and moderate agricultural streams, the quantity and quality of allochthonous input were not significantly different. However, the timing and composition of allochthonous materials were related to land use. Chlorophyll a and periphyton biomass did not vary among land use types. Leaf breakdown rates were significantly faster in light and moderate agricultural streams in comparison to forested and heavy agricultural streams. Slow breakdown rates in forested streams resulted from low nutrient concentration and cool stream temperature. The scarcity of shredding macroinvertebrates and sedimentation probably limited leaf breakdown in heavy agricultural streams. Though limited riparian vegetation along agricultural streams resulted in an energy supply equivalent to forested streams, agricultural land use may still have long term impacts on stream structure including nutrient concentrations, temperature, macroinvertebrate community, and sedimentation thus affecting stream ecosystem function. / Master of Science

Mountaintop removal and valley fill (MTRVF) mining has become a widespread means of coal extraction in the central Appalachians. During MTRVF several hundred meters of overburden are removed to access coal seams, and excess rubble is dumped into adjoining valleys and streams. Filling valleys eliminates stream headwaters and may result in loss of stream ecosystem functions, which are dependent on temporal and lateral connectivity in river networks. To determine the affect of MTRVF on stream ecosystem function, leaf breakdown, which is an ecosystem level attribute of forested streams, was measured in five streams draining MTRVF sites and five reference streams in central West Virginia. Leaf packs of white oak and red maple were installed in these streams in December 2007, leaves were collected in January, February, March, April, and June of 2008, and leaves were washed and processed in the lab. Leaf breakdown rates were significantly slower in filled streams. MTRVF streams were marked by high sediment levels, elevated base flow, elevated conductivity and pH, and a lower density and richness of shredding macroinvertebrates than reference sites, suggesting that slower leaf decay was the result of the combined set of altered conditions in MTRVF streams. Additionally, MTRVF streams showed no species-level difference between red maple and white oak breakdown rates, indicating that MTRVF inhibits control of ecosystem function exerted by leaf species characteristics. / Master of Science

Laser-plasma-based ion accelerators are becoming a versatile platform to drive different fields of applied research and life sciences, for example translational research in radiation oncology. To ensure stable accelerator performance, complete control over the ion source, i.e., the high-intensity laser-solid interaction, is required. However, idealized interaction conditions are almost impossible to reach, as the utilized high-power lasers always feature a non-negligible amount of light preceding the laser peak. This leading edge of the laser pulse usually exceeds the ionization potential of bound electrons much earlier than the arrival of the high-power laser peak and the solid-density target undergoes significant modifications even before the actual high-intensity laser-plasma interaction starts. Control over this so-called target pre-expansion is a key requirement to achieve quantitative agreement between numerical simulations and experiments of high-intensity laser-solid interactions. This thesis investigates several aspects that are relevant to improve the capability of simulations to model realistic experimental scenarios. The corresponding experiments are conducted with cryogenic hydrogen-jet targets and the DRACO-PW laser at peak intensities between 10^12 W/cm^2 and 10^21 W/cm^2 . The experimental implementation of time-resolved optical-probing diagnostics and technical innovations with respect to the technique of off-harmonic optical probing overcome the disturbances by parasitic plasma self-emission and allow for unprecedented observations of the target evolution during the laser-target interactions. The laser-induced breakdown of solids, i.e., the phase transition from the solid to the plasma state, can be considered as an heuristic starting point of high-intensity laser-solid interactions. As it is highly relevant to simulations of target pre-expansion, Chapter 3 of this thesis presents time-resolved measurements of laser-induced breakdown in laser-target interactions at peak intensities between 0.6 * 10^21 W/cm^2 and 5.7 * 10^21 W/cm^2 . By increasing the peak intensity, a lowering of the applicable threshold intensity of laser-induced breakdown well below the appearance intensity of barrier-suppression ionization occurs. The observation demonstrates the relevance of the pulse-duration dependence of laser-induced breakdown and laser-induced damage threshold to the starting point of high-intensity laser-solid interactions. To apply the results to other laser-target assemblies, we provide a detailed instruction of how to pinpoint the starting point by comparing measurements of the laser contrast with a characterization study of the target-specific thresholds of laser-induced breakdown at low laser intensity. Chapter 4 of this thesis presents an example of how optical-probing diagnostics are able to estimate target pre-expansion as a starting condition for particle-in-cell simulations. The measurement allows to restrict the surface gradient of the pre-expanded plasma density to an exponential scalelength between 0.06 um and 0.13 um. Furthermore, the plasma-expansion dynamics induced by the ultra-relativistic laser peak are computed and post-processed by ray-tracing simulations. A comparison to the experimental results yields that the formation of the measured shadowgrams is governed by refraction in the plasma-density gradients and that the observed volumetric transparency of the target at 1.4 ps after the laser peak is not caused by relativistically induced transparency but by plasma expansion into vacuum instead.

No description available.

In the last few years, estimators of the scale of a univariate distribution have been developed that are location-free in the sense that they do not depend on an estimate of the center of the underlying distribution. These proposed location-free estimators have generally been quite robust in terms of having a high breakdown point and can achieve a surprisingly high Gaussian efficiency. This idea has also been extended to the simple linear regression model, where typical estimators of the dispersion of the errors depend on an estimator of the regression line. The few estimators that have been developed that do not depend on a line estimator, called regression-free scale estimators, do achieve a high breakdown point but are useful mainly for data sets that have no replication at any regressor value. We propose new regression-free scale estimators that achieve a high breakdown point, can be quite efficient, and are useful when the data contain replication. Also, we propose a robust estimator of the common scale parameter in the k-sample model that reduces to an existing location-free estimator in the case of univariate data. We derive the breakdown point of this estimator as well as its maximum bias curve. Simulation results show that it can be quite efficient with Gaussian data. / Ph. D.

The subject of this paper is the use of Earned Value Management in a sub-project of aninfrastructure project FSK02 (Bypass Stockholm contract 02), a sub-project that is organized as a matrix organization. The questions are how the use of Earned Value Management in a sub-project of the Stockholm Bypass project works and how the use of Earned ValueManagement is affected by the matrix organization. The method used is qualitative interviews with eight people in a sub-project on their view of the use of Earned Value Management andof the organization. The result shows how Earned Value Management is implemented in the project and how the basis for the Earned Value Analysis is produced. Furthermore, it shows anumber of problems with the use of Earned Value Management, which are caused by the matrix organization. One problem is that the matrix organization can make the structure of thework packages unclear. A second problem is that the matrix organization can make those responsible for the work packages feel left outside the project. A third problem is that there isan experience of difficulties to implement procedures and guidelines in the matrix organization. All of these problems make the reporting of fact for the Earned Value Analysis difficult.

Nasal continuous positive airway pressure (CPAP) is reportedly superior to mechanical ventilation in the neonatal population by reducing bronchopulmonary dysplasia (BPD). The neonate is vulnerable to injury secondary to immature physiological systems and skin structures and the current CPAP devices place constant pressure on nares, nasal septum and forehead, increasing injury risk. Through the framework of comparative effectiveness research an examination of nasal interfaces currently used during neonatal CPAP was conducted in an effort to provide scientifically supported recommendations and improve clinical outcomes. The primary aim of this study was to determine differences in the frequency, severity and specific types of nasal injuries described when comparing different nasal CPAP interfaces (prongs/mask/rotation) used in the treatment of neonatal respiratory distress syndrome (RDS). A secondary aim of the study was to identify risk factors that may be associated with skin breakdown during nasal CPAP administration. A three group prospective randomized experimental design was used to study78 neonates <1500 grams receiving nasal CPAP using the same delivery system. The subjects were randomized into three groups: 1) continuous nasal prong group, 2) continuous nasal mask group, or 3) alternating mask/prongs group. Serial data collection included: demographic, biophysical measures and the Neonatal Skin Condition Scale (NSCS). This study demonstrated a significant difference in the frequency and severity of skin injury when utilizing a method of rotating mask and prong nasal interfaces during neonatal CPAP therapy; a useful clinical recommendation. Specific nursing care implications related to study findings include; choosing a device for best fit for infant (face shape and infant size); positioning of the CPAP device; developmental position of the infant; and focused skin assessment with rapid intervention. Standardized care including skin barriers, clinical expertise of nursing and respiratory therapy, and skin care management are strategies that warrant additional research.

Ce travail de thèse a été consacré à la compréhension du plasma induit par laser sur des matériaux organiqueset à l’application de la technique de laser-induced breakdown spectroscopy (LIBS) à l’analyse quantitative deces matériaux. L’ensemble des travaux contribue donc à approfondir notre connaissance sur les mécanismesphysiques impliqués dans l’interaction laser-matière, dans la génération du plasma et dans l’évolution decelui-ci au cours de son expansion dans le gaz ambiant avec la spécificité de s’adresser à des plasmas induitssur des cibles organiques. Ces travaux visent également à améliorer la performance de la LIBS pour l’analysede matériaux organiques. La spécificité concernant la cible organique répond au besoin actuel de lacommunauté internationale travaillant sur le développement de la LIBS, de mieux maîtriser le plasma induitsur ce genre de matériau qui présente des propriétés optiques bien spécifiques par rapport à des matériauxmieux connus pour l’ablation laser tels que des métaux. Elle répond également au besoin grandissant d’utiliserla technique LIBS aux matériaux organiques pour des applications dans les domaines environnementaux,agroalimentaires, ou encore biomédicaux. Ce mémoire de thèse a été rédigé selon l’organisation suivante. Après l’Introduction Générale qui préciseles contextes scientifiques et technologiques, le Chapitre I rappelle les principes de base nécessaires à lacompréhension du phénomène de génération de plasma par ablation laser, et de l’évolution de celui-ci dans ungaz ambiant. L’accent a été mis sur l’ablation des matériaux organiques. Les procédures et les techniques dediagnostic du plasma induit par laser sont ensuite présentées en insistant sur la nature transitoire etinhomogène d’un plasma en expansion. Le chapitre II s’intéresse à la génération et l’évolution du plasmainduit sur la peau d’une pomme de terre, un échantillon typique de produit agroalimentaire. La caractéristiquedu plasma induit sur une cible organique molle et humide, comme une pomme de terre fraîche était quelquechose d’inconnu au démarrage de la thèse et constituait une base nécessaire à l’analyse quantitative deséléments métalliques en traces et ultra-traces contenus dans un tel échantillon. A l’issue de cettecaractérisation, les données analytiques semi-quantitatives ont été extraites des spectres LIBS correspondant àla peau d’une pomme de terre. Le Chapitre III se situe dans la continuité du Chapitre II pour l’application de laLIBS à des matériaux organiques. Une étude comparative d’analyse de la poudre de lait par la LIBS et parl’ICP-AES permet une évaluation de la performance d’analyse quantitative de la LIBS pour des échantillonsorganiques, et une validation de la procédure CF-LIBS. A la différence des Chapitres II et III où les élémentsde traces métalliques étaient au centre de notre attention, le Chapitre IV étudie le comportement des élémentsmajeurs qui composent la matrice d’un matériau organique, qui sont les 4 éléments organiques, H, C, O, N. Ala décomposition d’un matériau organique par ablation laser, ces éléments peuvent se présenter sous la formede fragments moléculaires, ou encore se recombiner en des espèces moléculaires. Nous étudions alors dans ceChapitre l’évolution de ces espèces en fonction des paramètres du laser utilisé, et notamment la longueurd’onde. Le mémoire se termine par une conclusion générale et des perspectives. / This PhD work was devoted to the understanding of the laser-induced plasma on organic materials and theapplication of laser-induced breakdown spectroscopy (LIBS) to quantitative analysis of these materials. Itcontributes to deepen our knowledge on the physical mechanisms involved in laser-matter interaction, plasmageneration, evolution and expansion of the plasma into the ambient gas, with emphasis on plasmas induced onorganic targets. It also intends to improve the performance of LIBS for the analysis of organic materials. Thespecificity for organic targets fits the current focus of the international community working on LIBS, toimprove the control of the plasma induced on this kind of material which has a distinguished optical prosperitywith respect to that of metals, better known for laser ablation. It addresses also the growing need to apply theLIBS technique to organic materials for different applications in the environmental, food, or biomedicaldomains. The works in this thesis were therefore presented in this thesis document according to the followingorganization.After the General Introduction which introduces the scientific and technological contexts, Chapter Irecalls the basic theoretical elements necessary to understand the phenomenon of plasma generation by laserablation, and its evolution in the background gas. Ablation of organic material is emphasized. Procedures andtechniques of diagnostics of laser-induced plasma were then presented with a focus on the transient andinhomogeneous nature of the expanding plasma. Chapter II focuses on the generation and the evolution of theplasma induced on the skin of a potato, a typical sample of agricultural product. The characteristics of plasmainduced on a soft and wet organic target, such as a fresh potato, was something unknown when the thesis workstarted. These characteristics provide the necessary basis for the quantitative analysis of the trace andultra-trace metallic elements in these samples. Following this characterization, semi-quantitative analyticalresults were extracted from LIBS spectra corresponding to potato skin. Chapter III is presented in thecontinuity of Chapter II for the application of LIBS to the quantitative analysis of organic materials. Acomparative study on the analytical results with LIBS and ICP-AES for milk powders allows an assessment ofthe performances of quantitative analysis by LIBS for organic materials, and a validation of the CF-LIBSprocedure that we have developed. Different from Chapters II and III where attention was paid to trace metalelements, Chapter IV studies the behavior of the major elements that make up the matrix of organic material,which are 4 known organic elements: H, C, O, N. During the decomposition of organic material by laserablation, these elements can be found in the form of molecular fragments, or recombined into molecularspecies. We then study in this Chapter the evolution of these species as a function of the laser ablationparameters, the laser wavelength in particular. The thesis document ends with a general conclusion andoutlooks.

The impact of physical design characteristics on backend dielectric reliability was modeled. The impact of different interconnect geometries on backend low-k time dependent dielectric breakdown was reported and modeled. Physical design parameters that are crucial to backend dielectric reliability were identified. A methodology was proposed for determining chip reliability but combining the insights gathered by modeling the impact of physical design on backend dielectric breakdown. A methodology to model variation in device parameters and characteristics was proposed. New methods of electrical and physical parameter extraction were proposed. Models that consider systematic and random source of variation in electrical and physical parameters of CMOS devices were proposed, to aid in circuit design and timing analysis.

Frontend and backend wearout mechanisms are major reliability concerns for modern microprocessors. In this research, a framework which contains modules for negative bias temperature instability (NBTI), positive bias temperature instability (PBTI), hot carrier injection (HCI), gate-oxide breakdown (GOBD), backend time-dependent dielectric breakdown (BTDDB), electromigration (EM), and stress-induced voiding (SIV) is proposed to analyze the impact of each wearout mechanism on state-of-art microprocessors and to accurately estimate microprocessor lifetimes due to each wearout mechanism. Taking into account the detailed thermal profiles, electrical stress profiles and a variety of use scenarios, composed of a fraction of time in operation, a fraction of time in standby, and a fraction of time when the system is off, this work provides insight into lifetime-limiting wearout mechanisms, along with the reliability-critical microprocessor functional units for a system. This enables circuit designers to know if their designs will achieve an adequate lifetime and further make any updates in the designs to enhance reliability prior to committing the designs to manufacture.