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Book
vii, 420 pages : illustrations ; 23 cm. + 1 CD-ROM.
Green Library
Book
viii, 291 pages : illustrations (partly color) ; 24 cm.
Music Library
Book
ix, 241 pages ; 24 cm.
Green Library
Book
1 online resource.
Platforms like Amazon Mechanical Turk have made it possible for hundreds of people to come together to produce creative work at massive scale. Complex work is often managed by breaking down a large task into smaller subtasks; the sub-results produced by these subtasks are combined to create the final result. Projects like the Johnny Cash Project, for example, asked workers to draw individual frames which were combined to create a reinterpretation of a music video. Another commonly used technique to manage crowdsourced work is to build a workflow that connects individual tasks through concretely defined inputs and outputs. By splitting a larger work into smaller parts that can be completed independently, these crowdsourced workflows can often accomplish work more quickly or accurately than an individual. However, these techniques can only be applied to certain kinds of work: the task must be divisible into independent subtasks, which often means that subtasks are designed to help accomplish a predetermined desired outcome. As a result, crowds have difficulty completing tasks with complex interdependent parts (such as writing stories or composing music), because modifying one section may require changes in other sections of the work. Rather than splitting complex work into independent steps, what if we could enable the crowd to engage in a creative process that looks more like that of an expert? By doing this, we may expand the crowd's ability to work together on complex creative projects. This dissertation takes inspiration from expert creative practices to design new crowdsourcing and social computing techniques for accomplishing complex creative work online. These techniques are developed through three systems: Ensemble, Mechanical Novel, and Mosaic. In Ensemble, I use the practice of developing and revising constraints to split the task of writing a short fiction between a leader (who defines constraints and goals for a story) and the crowd (who executes works based on these goals). Mechanical Novel expands on this by studying how crowds can define high-level goals for themselves, without needing a central leader to coordinate work. Lastly, Mosaic generalizes this idea of designing collaborative systems based on expert practices by exploring design affordances for an online community that values non-traditional success outcomes such as early work, failure, and experimentation. These systems demonstrate how expert creative practices can be built into the design of collaborative creativity support tools, and show how designing for exploration can result in better creative outcomes than just focusing on success.
Book
1 online resource.
This two-part mixed methods study applies a dual processing model to explore the effects of digitally mediated empathy interventions on bias against marginalized groups, justice sensitivity, and helping behavior. Previous findings in the empathy literature suggest that while affective and cognitive empathy may be utilized to alter someone's perception of a marginalized group in a beneficial manner, the complex relationship between an individual and the technology they use may modify these effects and render previous findings incomplete. Results revealed that prompting affective or cognitive empathy in response to video stimuli did not elicit positive perspective-taking or decrease bias against these groups. For scales of homophobia that experienced significant interaction effects, the distraction and cued comment condition had the least amount of bias. Similarly, for the illegal alien scale, the distraction condition produced the least biased results. Findings from the justice sensitivity scales show that the empathy condition increased personal justice sensitivity, while those in the distraction condition experienced comparatively higher levels of "other-oriented" concern. These findings suggest that instead of eliciting positive feelings about the marginalized groups, the empathy-specific prompts activated biases against the individual. Additional findings for the effects on helping behavior suggest a more nuanced outcome that does not correlate with outcomes expected from previous psychological research. All of the results suggest that digitally mediated video stimuli designed to elicit empathy for marginalized groups may have the opposite effect due to the complex nature of the interaction between online media and culture.
Book
xi, 790 pages : many illustrations (some color) ; 25 cm.
Art & Architecture Library (Bowes)
Book
289 pages ; 24 cm.
Green Library
Book
308 pages ; 24 cm.
  • Dank
  • Einleitung
  • Forschungsbericht
  • Intertextualität als Interpretationsgewinn
  • Aspekte und Ansätze anwendungsorientierter Modelle
  • Methodische Herangehensweise
  • Umgang mit und Integration von Literatur in den Jahrestagen
  • Titel und Untertitel der Jahrestage
  • Der Anfang der Jahrestage
  • Eine beispielhafte Lektüre
  • Fazit : Erscheinungsformen der Integration
  • Die Bedeutung der literarischen Zitate für die Handlung
  • Motivgeschichten : Proust, Johnson und die Ebene des Traums
  • Rekonstruierte Geschichten : von sprachlichen Anklängen durchzogene Mutmassungen
  • Liebes- und Verlustgeschichten : Poetisierung und Reflexion mithilfe von Literatur
  • Schulgeschichten : Schullektüren von Gesine
  • Erziehungsgeschichte : Maries Literaturrezeption
  • Moralgeschichten : das richtige Handeln und die Literatur
  • Die Bedeutung der literarischen Zitate für die erzählerische Vermittlung
  • Funktionen : Strukturierung
  • Wiederholt verwendete Zitate : Prätexte mit leitmotivischem Charakter
  • Vorlage für Erzählepisoden : Strukturelle Zitate
  • Funktionen : Kontextualisierung
  • Repräsentation der Erzähltradition : Zitierende Zitate
  • Intensive Kontextualisierung : Titelzitate und -anspielungen sowie Interfiguralität
  • Funktionen : Verfremdung
  • Betonung der Mehrsprachigkeit : Zitate in Originalsprache
  • Unterbrechende Spurenauslegung : Pseudozitate und zweifelhafte Anspielungen
  • Fazit und Ausblick
  • Literaturverzeichnis
  • Primärliteratur
  • Sekundärliteratur
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Green Library
Book
1 online resource.
Distributed photovoltaic (PV) generation is growing rapidly due to renewable-energy policies, business innovation, and new technology. The variability and volatility of solar generation causes challenges when operating the grid. Given the current physical infrastructure and operational policies this results in limits on distributed PV generation. What the limit is to the penetration of PV is studied by analyzing the behavior of distributed PV generation and a model of the load. We investigate how to represent the power output from distributed PV generation. We propose a reduced-form approach for constructing maximum PV power curves, which describe the maximum power from a group of PV systems at any time instance. Unlike a structural approach used typically by PV providers, the reduced-form approach requires no information about configuration or specification of each PV system in the group. We show how a grid operator can use maximum power curves in various applications such as finding a simple limit to PV installation, defining volatility distinctly from variability, and constructing a short-term PV power forecast system. A key requirement is a model of the load. Analogous to the maximum power curve, a load reference curve is proposed with a simple definition and shown to improve the performance of a short-term load forecast. Lastly, a simulation of the grid operation using our forecast systems and a typical set of existing infrastructures is performed to measure the risk of demand-supply imbalance. The maximum level of distributed PV installation given an acceptable level of risk is established. Options of adding additional ancillary services and implementing PV curtailment to increase the maximum level of distributed PV installation are also investigated.
Book
1 online resource.
The partial differential equations governing multiphase flow and transport in heterogeneous porous media are highly nonlinear. Therefore, in the fully implicit finite-volume method, solving the algebraic systems at each time step is challenging and accounts for the majority of the simulation cost. We present numerical schemes and solution strategies applicable to general-purpose simulation that reduce the computational cost by drastically improving the nonlinear convergence. In the discretized transport problem, the interfacial approximation of the functions of saturation -- i.e., phase relative permeability and capillary pressure -- has a strong impact on the strength of the nonlinearities. We generalize and analyze an approximation method tailored to the underlying three-phase flow physics and based on Implicit Hybrid Upwinding (IHU) that results in fast nonlinear convergence. This is achieved with a differentiable and monotone numerical flux for two- and three-phase transport obtained from separate evaluations of the viscous, buoyancy, and capillary fluxes. Then, using IHU, we construct an efficient physically based discretization scheme for the mixed elliptic-parabolic problem in which the flow is coupled to the transport of species. The resulting IHU scheme is more general and more efficient than the saturation damping methods previously used to improve the nonlinear convergence. In addition, to correctly represent the trapping mechanisms associated with capillary heterogeneity, the proposed finite-volume scheme accounts for spatially discontinuous relative permeabilities and capillary pressure at the boundary between different rock types. Specifically, we design a robust numerical method that combines IHU with discrete transmission conditions between rock regions to improve the accuracy of the flux approximation compared to the standard Phase-Potential Upwinding (PPU) scheme. Importantly, we present a mathematical analysis that places this new fully implicit finite-volume scheme on a strong theoretical foundation. The mathematical study is supported by challenging heterogeneous two- and three-phase numerical tests. These computational examples demonstrate that the IHU scheme results in significant reductions in the number of nonlinear iterations compared to the commonly used PPU scheme for viscous-, buoyancy-, and capillary-dominated flow. Finally, we extend a nonlinear solution strategy in which the flow variables (pressure) and the transport variables (saturation and composition) are updated sequentially. The saturation and composition update relies on a reordering of the control volumes exploiting the directionality of the transport problem and is done locally in decreasing order of potential. We show that this procedure leads to a drastic improvement in the nonlinear convergence properties compared to Newton's method with damping for immiscible, Black-Oil, and compositional problems with strong buoyancy.
Book
1 online resource.
Regeneration is a process that requires tightly regulated proliferation, differentiation, and tissue remodeling. Classical model organisms such as C. elegans, D. melanogaster, and M. musculus have limited regenerative capabilities therefore we present the freshwater planarian Schmidtea mediterranea, which provides an ideal system to study the role of stem cells in regeneration. This immortal adult organism boasts excellent regenerative capabilities driven by a stem cell population called neoblasts. The neoblast population is the only mitotically active cell type in planarians and can be easily manipulated without concern for embryonic requirements. This unique model also allows for the study of human embryonic stem cell genes in a simpler in vivo system. Thus S. mediterranea offers the opportunity to accelerate the studies and understanding of stem cell biology and regeneration in the environment of a living organism. GATA transcription factors are DNA binding proteins that are well-known master regulators of development. Through the activation and repression of transcription, these factors direct cellular differentiation toward lineage specification. Here we used loss-of-function experiments to understand the role of the GATA4/5/6 subfamily in the differentiation of neoblasts. S. mediterranea has a single homolog of mammalian GATA-4, -5, and -6, Smed-gata4/5/6, which is expressed primarily in the planarian intestine and in some neoblasts. Smed-gata4/5/6 knockdown results in perturbed homeostasis and regeneration, eventually leading to planarian death. Loss of Smed-gata4/5/6 disrupts intestinal differentiation and also affects non-intestinal lineages. During late time points of regeneration, Smed-gata4/5/6 loss leads to decreased neoblast proliferation and gene expression of neoblast subpopulations. These data support the conserved role of Smed-gata4/5/6 in intestinal differentiation and indicate the intestine may act as a neoblast niche. Our preliminary work on Experimental Evolution through irradiation exposure shows a sub-lethal dose of irradiation eliminates neoblast expression after 24 hours and expression recovery occurs after 3-4 weeks. This demonstrates S. mediterranea is a malleable model organism that can be used to study the link between regeneration and cancer.
Book
231 pages ; 23 cm.
Green Library
Book
348 pages : illustrations ; 24 cm.
Green Library
Book
x, 379 pages ; 24 cm.
Green Library
Book
1 online resource.
This dissertation explores two major lines of research concerning ultrafast electron dynamics in atoms and molecules. The first part investigates the dynamics of photoionization in intense laser fields on the attosecond time scale. A new technique using a weak probing field at half the frequency of the strong ionizing laser field reveals attosecond delays in the above-threshold ionization process. We observe the influence of the combined Coulomb-laser potential on the spectral phase of the photoelectron. In the second part, an experiment which imaged the uncoupling of electron motion from the molecular frame in rotating molecules is described. A coherent wave packet in the 4f Rydberg manifold of molecular nitrogen is created and its motion is probed in time. This allows for a direct observation in the time domain of a non-Born-Oppenheimer regime, known as the l-uncoupling regime, that up until now has only been inferred from spectroscopic data.
Book
xv, 304 pages : 7 illustrations ; 23 cm.
Green Library
Book
262 pages ; 22 cm.
Green Library
Book
1 online resource.
The world's ever-increasing needs for energy, currently fulfilled primarily by the combustion of hydrocarbon fuels, are demanding development of more efficient and cleaner combustion processes, which ultimately requires improved knowledge of fundamental combustion kinetics. Present in the combustion of most hydrocarbon fuels, aldehydes are important intermediate species that hold key information to such knowledge. Recognizing the critical role of aldehydes in combustion research, the current study presents (1) an advanced aldehydes diagnostic system for use in combustion environments, (2) a set of improved rate constant measurements for several key reactions of aldehydes, and (3) a toolbox that will facilitate future kinetics studies of aldehydes. A system of continuous-wavelength (CW) laser absorption diagnostic methods was developed for the quantitative measurement of formaldehyde (CH2O) and acetaldehyde (CH3CHO) in shock tube kinetic studies. Investigation of the high-temperature CH2O spectrum showed that the optimal wavelength for CH2O detection using commercially available lasers was near 2896 cm−1. By exploiting the structural difference between the absorption spectra of CH2O and that of broadband interfering species, the current study proposed a two-color (2895.92 and 2895.60 cm−1) interference-free detection scheme for CH2O sensing in combustion environments. A third color (32601.10 cm−1) was also added to develop a UV/IR detection scheme for combined CH3CHO/CH2O measurements. Aldehyde absorption cross-sections at all three colors were measured behind reflected shock waves over a wide range of temperatures (600--1800 K) and pressures (0.8--3.6 atm), with an uncertainty of ±5%. The diagnostic system was then validated in two well-controlled experiments, and demonstrated in shock tube pyrolysis experiments of 1,3,5-trioxane, CH2O and CH3CHO. The rate constant of acetaldehyde thermal dissociation, CH3CHO (+M) = CH3 + HCO (+M), was measured behind reflected shock waves at temperatures of 1273 - 1618 K using a sensitive CO diagnostic. Example simulations of existing reaction mechanisms updated with the current rate constant values demonstrated substantial improvements with regard to the acetaldehyde pyrolysis chemistry. The rate constant of the H-abstraction reaction of formaldehyde (CH2O) by hydrogen atoms (H), CH2O + H = H2 + HCO, was also studied behind reflected shock waves using the same CO absorption diagnostic, over temperatures of 1304--2006 K. These experiments were carefully designed to maintain relatively constant H radical concentrations, which significantly boosted the measurement sensitivity of the target reaction and suppressed the influence of interfering reactions. Compared to previous studies, the current work has significantly reduced the measurement uncertainty. The overall rate constants of the H-abstraction reactions of 10 different aldehydes, namely formaldehyde (CH2O), acetaldehyde (CH3CHO), propionaldehyde (C2H5CHO) and n-butyraldehyde (n-C3H7CHO), isobutyraldehyde (i-C3H7CHO), n-valeraldehyde (n-C4H9CHO), isovaleraldehyde (i-C4H9CHO), trans-2-pentenal (C2H5CHCHCHO), trimethylacetaldehyde ((CH3)3CCHO) and benzaldehyde (C6H5CHO), by hydroxyl radicals (OH), were studied behind reflected shock waves at temperatures of 958 -- 1391 K, using UV laser absorption at 306.69 nm. The current study reported the first direct rate constant measurement for C2 and higher aldehydes + OH at temperatures above 1000 K. To aid future kinetics research in shock tubes, a novel toolset of advanced laser absorption diagnostics, namely shock-tube-integrated cavity-enhanced absorption spectroscopy (CEAS), was also developed in the current study. This CEAS technique utilized high reflectivity mirrors directly mounted on the shock tube to enhance the effective optical pathlength in shock tube/laser absorption measurements by factors of about 50 - 90, thereby greatly improving the species detection limits in shock tube kinetics studies. A CW laser CEAS method was explored and applied to ultra-sensitive CO detection in rate constant measurements for the acetone thermal dissociation reaction, CH3COCH3 (+ M) = CH3 + CH3CO (+ M), over 1004-1094 K. A pulsed-laser CEAS was also explored in the current study to develop an improved laser absorption diagnostic for CH3 at 216.62 nm. Example application of this diagnostic was demonstrated in rate constant measurements for the thermal dissociation reaction of methane, CH4 + M = CH3 + H + M over 1487 - 1866 K. This CEAS toolset should prove very useful in future shock tube kinetics studies, including but not limited to, the studies of aldehydes.
Book
1 online resource.
The slow acquisition speed of magnetic resonance imaging (MRI) hinders its wider adoption as a diagnostic and research tool. In recent years, simultaneous multi-slice (SMS) MRI has been proposed to accelerate MRI scans. The main focus of this dissertation is to develop a generic and accurate data reconstruction framework, termed hybrid-space SENSE, for SMS MRI. To evaluate the signal-to-noise ratio (SNR) loss in the reconstruction, analytical geometry-factor maps are derived. Under the proposed framework, a matrix-decoding Nyquist ghosting correction method is further developed to conduct slice-specific Nyquist ghosting correction for SMS echo planar imaging. This dissertation also presents work on three other aspects of SMS MRI: one is designing undersampling strategies that generate incoherent interslice aliasing; another is de-signing autocalibrating undersampling schemes; the third aspect is designing signal excitation radiofrequency (RF) pulse with reduced peak amplitude.
Book
xi, 413 pages ; 23 cm.
Green Library