GESUALDO’S MORO LASSO AND THE FREUDIAN REPETITION COMPULSION

We explore the complex psychological condition of the first-person experiencing subject (both literary and musical) presented in Carlo Gesualdo’s madrigal Moro lasso. We compare the textual and musical repetitions within Moro lasso to Sigmund Freud’s concept of the repetition compulsion, in which a person repeats a traumatic event over and over again, either in thoughts or actions, including dreams and hallucinations. Gesualdo’s technique of repeating small elements many times in preparation for larger structural patterns of repetition may perhaps represent or allegorize a version of the Freudian repetition compulsion. We specifically do not address the possible psychoanalysis of Carlo Gesualdo, the historical man, but rather the first-person voice of the madrigal. We do not attempt in this article to provide a comparative or historical study of the Italian madrigal, nor do we attempt to trace the history of Gesualdo’s many innovative musical techniques through the works of previous composers. Instead, we investigate the psychological qualities of repetition, especially complex and subtle forms of repetitive structure, as they appear in a single musical work, the madrigal Moro lasso. By examining the essential diegetic trajectory of the music, we retrieve something of significance about an important and distinctive expressive aspect of the madrigal Moro lasso, and also demonstrate that the composer’s literary persona actively interacts with the creation of meaning in this work and occasionally suggests complex and potentially conflicting levels of discourse

D. A. Kolb’s Theory of Experiential Learning: Implications for the Development of Music Theory Instructional Material

This research project evaluates the effectiveness of specific music theory instructional strategies in terms of D. A. Kolb’s theory of experiential learning and Kolb’s typology of individual learning style. The project provides an original methodology for the adaptation of music theory instructional material to the individual learning style types described in Kolb’s typology. The study compares the relative effectiveness of two music theory instructional sequences, one of which is adapted for all of the learning style modalities described in Kolb’s typology, and the other adapted for only a limited number of Kolb’s learning style types. In order to compare the potential “learning outcomes” produced by these instructional sequences, a detailed study is proposed, in which computer based instruction (CBI) will deliver the instructional sequences to research participants and electronically record the participants’ responses. The current study demonstrates the effective aspects of the original methodology and suggests methods for the successful adaptation of music theory instructional material to individual student learning styles

Non-Linear and Multi-Linear Time in Beethoven's Opus 127: An Analytical Study of the "Krakow" Sketch Materials

Beethoven's complex manipulation of formal structures, especially his tendency to build important connections and transformative continuities between non-adjacent sections of musical works, may be seen to function as an attempt to control and sometimes to distort the listener's perception of both the narrative process of musical directionality, as well as the subjective interpretation of time itself. Temporal distortion often lies at the heart of Beethoven's complex contrapuntal language, demonstrated equally through the composer's often enigmatic disruption of phrase-periodic gestures, as well as by occasional instances of overtly incongruous temporal shifts. The "Krakow" collection of compositional sketches for Beethoven's String Quartet in E-Flat, Op. 127, provides a number of instances of "non-linear" or "multi-linear" musical continuity. The term "Krakow" sketches, when referenced in this dissertation, specifically designates the group of Beethoven manuscripts possessed by the Biblioteka Jagiellońska in Krakow, Poland, but which formerly were held by the Royal Library in Berlin. Structural voice-leading analyses are provided for selected portions of the "Krakow" collection; these analyses are then compared to voice-leading graphs and analytical reductions of the corresponding material from Beethoven's published versions of the same musical passages. In some cases the sketches supply almost complete texts, for which critical transcriptions are included as extended examples within the dissertation. The primary analytical technique applied to both compositional sketches as well as to complete musical texts derives from Heinrich Schenker's theory of structural voice-leading and graphical reduction. An important method of critical assessment, from which a number of theoretical arguments are developed, is the contention that Beethoven's contrapuntal language, at least in regard to the op. 127 String Quartet, relies heavily upon a temporal distortion of both form and phrase-periodic gestures, requiring the listener to actively re-construct the continuity of Beethoven's subjective formal archetypes

A hybrid model of ion-induced syrface modification with prompt molecular dynamics and lattice-free kinetic Monte Carlo diffusion

Ion beam nanopatterning is a robust, scalable technique for modification and fabrication of nanostructured surfaces. An ion beam incident on a surface acts as an athermal source of particles and energy, driving the surface far from equilibrium and leading to the emergence of metastable compositional and morphological phases. However, the fine process control needed for advanced nanotechnology applications remains elusive due to a lack of fundamental physical understanding of nanostructure formation and growth on complex, multi-component surfaces such as III-V semiconductors or metal-silicon systems. Recent experimental progress in the field has demonstrated the evolution of a three-dimensionally complex surface compositional profile during low-energy ion beam irradiation of III-V semiconductor systems such as GaSb, which is a necessary precursor to formation of ordered nanostructures. Novel analysis of x-ray scattering measurements indicates that the nanopatterning kinetics are described by highly nonlinear, nucleation-and-growth kinetics which are not included in any theoretical treatment of ion beam nanopatterning of compositionally complex materials. To elucidate the compositionally driven mechanisms which lead to these kinetics, large-scale computational simulations have been designed and carried out on the Blue Waters supercomputer at the University of Illinois and the Advanced Cyberinfrastructure (ACI) system at Pennsylvania State University. Large-scale molecular dynamics (MD) simulations of 500 eV Kr+ ion irradiation of amorphous GaSb surfaces have connected the compositional depth profile observed in experiments to lateral compositional gradients via thermodynamically driven phase separation. This lateral compositional evolution is a necessary precursor for a pattern-forming surface instability. Other large-scale MD studies of GaSb(110) irradiation from initially-pristine surface conditions have shown the formation of Sb protoclusters due to prompt ion-induced collisional effects at high irradiation fluences exceeding 1015 cm-2. The protocluster formation is accompanied by significant structural transformation of the surface, including bulk amorphization, reduction of average per-atom bonding energies, and prevalence of non-tetrahedral bonding states which would otherwise characterize an amorphous semiconductor surface. However, a long temporal scale mechanism such as surface diffusion is necessary to connect these disruptive phenomena into a complete model of nanopattern formation. Finally, a large battery of single-ion impact MD simulations under a range of ion beam parameters into GaSb surfaces with variable compositional depth profiles has elucidated the connection between lateral variation of the compositional depth profile and local morphological instability. Specifically, the presence of a compositional phase interface near the surface leads to an increase in ion-induced energy deposition at or near the surface monolayer, which leads to enhanced surface erosion (i.e., sputtering) when the surface monolayer is Sb-enriched and/or when the sub-surface is Ga-enriched. Given this finding, the key physical mechanisms which remain to be deciphered are those which drive the three-dimensional compositional evolution of the ion-irradiated surface and activate this sputtering instability. Accordingly, the culmination this work is a highly-parallelized, hybrid molecular dynamics/kinetic Monte Carlo (MD/KMC) model designed to simulate nanopattern formation on III-V and other compositionally complex surfaces. This diffusion model relies on a lattice-free point defect characterization method to analyze the defect distribution in the highly disordered ion irradiated surface. These defects then mediate diffusion events which are identified using per-atom neighbor lists and bond structural configurations to determine the activation energy. Therefore, the model is termed structural kinetic Monte Carlo (SKMC). The SKMC approach allows computational modeling to extend beyond the prompt temporal regime accessible by MD alone, addressing the three-dimensionally complex evolution of the surface beyond the microsecond scale. By alternating between MD ion irradiation steps and SKMC steps, a complete atomistic model of ion beam nanopatterning is therefore constructed. The application of this new modeling approach is demonstrated for the case of ion beam irradiation of cleaved GaSb surfaces up to a fluence of 4 × 1015 cm-2. Specifically, hybrid MD/SKMC simulations test the hypothesis that prompt cluster formation, diffusion-driven cluster growth, and compositional depth profile-modulated sputtering yields are the fundamental mechanisms driving nanopattern formation and growth. This modeling approach has broad applications beyond semiconductor surfaces to any class of complex nanomaterials under ion beam or plasma irradiation, such as high-entropy alloys currently under consideration as structural materials for fusion device applications

Large-scale molecular dynamics investigations of ion-induced compositional dynamics leading to nanopattern formation at semiconductor surfaces

Ion beam nanopatterning has been demonstrated to be a versatile method for obtaining a wide variety of surface features on a broad range of materials, with structures such as ripples, quantum dots, terraces, and ordered holes being obtained for various experimental conditions. However, theoretical modeling is well behind the experimental progress, and even for “simple” systems such as noble gas ion irradiation of silicon surfaces there exist several competing models proposing different pattern-forming mechanisms. For more complex systems, such as ion irradiation of binary alloys, the landscape of potential pattern-forming mechanisms remains very much a terra incognita, to the point where two models can predict the same surface morphologies while predicting diametrically-opposed surface compositional profiles. This knowledge chasm between experiments and theories requires a fundamental understanding of the ion-induced mechanisms that can lead to surface instabilities, to eliminate the dependence on simplifying assumptions and tunable parameters of existing modeling approaches. To close this gap, atomistic computational modeling is needed to allow direct observation of the ion-surface interactions at smaller length and time scales than can be accessed by experimental characterization techniques. At the same time, atomistic simulations must be able to account for changes over time in the surface structure or composition, which will influence the nature of the ion-surface interactions. The results from these atomistic simulations and the physical understanding gained can then be used as the basis for or as parametric inputs to multiscale models of nanopattern formation. Such a model has previously been developed, which is a hybrid molecular dynamics/kinetic Monte Carlo (MD/kMC) atomistic simulation that uses so-called “crater functions” obtained from MD simulations of single-ion impacts, combined with an atomistic kMC model of surface diffusion, to provide a complete description of the ion-surface interaction and the resulting surface nanopatterning without reliance on the assumptions and arbitrary parameters from other models. This simple computational model provides a well-tested starting point from which additional mechanisms can be implemented and used to study more complex material systems. Here, large-scale MD simulations are used to study the ion-induced compositional and phase dynamics, enabling the mechanisms that can cause patterning instabilities to be elucidated and characterized. The compositional evolution of GaSb under low-energy ion irradiation is studied by massive-scale MD simulations, which have been carried out on the Blue Waters high-performance computing platform at the University of Illinois. The first set of simulations consist of 500 eV Kr+ bombardment of a GaSb surface with a significantly-altered compositional profile designed to resemble experimental observations of the compositional depth profile at the onset of nanopattern formation. In regions of altered composition, thermodynamic phase separation is observed as the surface atoms rearrange themselves into clusters of the enriched component within 50/50 amorphous GaSb. Additionally, the pure Sb clusters in Sb-enriched regions self-organize into crystalline lattices, while the pure Ga clusters in Ga-enriched regions remain in an amorphous state. These results have demonstrated for the first time, using MD simulations, that the compositional depth variation observed from experiments can lead to a lateral compositional variation that may provide a potential pattern-forming instability. The second set of simulations consist of 500 eV ion irradiation of initially-pristine GaSb(110) by Ne+, Ar+, and Kr+ ion species up to the experimentally-relevant fluence of 7.5 × 1015 cm-2 with the goal of discovering how the ion-induced mechanisms leading to the formation of a compositional depth profile. While the surface quickly becomes amorphous under sustained ion bombardment, no ion species led to the emergence of a compositional depth profile. However, smaller “protoclusters” of Sb were formed in the subsurface, even in the absence of the compositional change necessary to drive thermodynamic phase separation. These protoclusters are conjectured to be formed from Sb precipitation out of the GaSb melt volume from ion-induced thermal spikes, and may function as the initial “seeds” that grow large enough to cause a compositional depth profile to form under the influence of additional mechanisms acting on timescales beyond the limits of MD simulations. The effects of implanted noble gas ions in Si are also studied with the use of high-fluence molecular dynamics simulations to reach cumulative ion fluences of ≥ 3 × 1015 cm-2. Ion species of Ne+, Ar+, Kr+, and Xe+ were studied with incident energies per ion ranging from 20 to 1000 eV and ion incidence angles ranging from 0° to 85°. The implanted ions tend to form clusters beneath the surface, which are formed purely by the kinetic motion of the ions and not due to diffusive processes. A cluster degassing mechanism is observed, which occurs when the Si surface above a cluster is eroded by ion sputtering and the gas atoms rapidly vacate the cluster. Immediately after the cluster has degassed, a rapid inflow of mass from the surrounding surface occurs to fill the resulting void. The combination of the cluster degassing and the resulting mass flow has a highly disruptive effect on the local surface morphology, which could destroy nanopattern “seeds” at the surface, which may be a missing mechanism from existing models of surface nanopatterning that can correct the quantitative inaccuracies of those models. Additionally, the shear stress distribution and elastic modulus were calculated for the ion-bombarded surfaces. While the shear stress distribution is in general agreement with expectation from previous computational studies, the strong variance in the stress depth profiles at different fluences suggests a highly-localized contribution from the implanted ion clusters which must be considered in stress-based models of ion beam nanopatterning. Comparing the elastic moduli for surfaces with and without ion clusters confirms that the presence of clusters within the surface has a significant influence on the mechanical properties of that surface

Qubit Allocation for Noisy Intermediate-Scale Quantum Computers

In the era of noisy-intermediate-scale quantum computers, we expect to see quantum devices with increasing numbers of qubits emerge in the foreseeable future. To practically run quantum programs, logical qubits have to be mapped to the physical qubits by a qubit allocation algorithm. However, on present day devices, qubits differ by their error rate and connectivity. Here, we establish and demonstrate on current experimental devices a new allocation algorithm that combines the simulated annealing method with local search of the solution space using Dijkstra's algorithm. Our algorithm takes into account the weighted connectivity constraints of both the quantum hardware and the quantum program being compiled. New quantum programs will enable unprecedented developments in physics, chemistry, and materials science and our work offers an important new pathway toward optimizing compilers for quantum programs.Comment: 6 pages, 3 figure

Ion Irradiation Simulations to Study Quantum Dot Formation in III-V Semiconductors

Quantum dot (QD) formation on III-V semiconductor surfaces using ion irradiation has attracted significant experimental and theoretical interests for industrial applications. Various models have claimed to predict QD formation on gallium antimonide (GaSb) surfaces, but a glaring knowledge gap highlighted by recent experiments suggest a preliminary morphology of the compositional depth profile leading to QD emergence. To understand how the evolving composition induces prompt effects preceding QD formation, atomistic simulations are implemented using Molecular Dynamics (MD) to simulate Kr+ ion impact simulations onto the GaSb surface. We present single ion bombardment simulations on GaSb surfaces with altered compositions, which elucidate the dependence of ion-surface interactions on surface composition. The size and shape of ion range, energy transfer, and momentum transfer distributions exhibit a strong dependence on interfacial effects produced by layers of different compositions. Specifically, we find that the distributions exhibit peaks at the interfaces, which means that incident ions are “trapped” by the presence of interfaces. Using this and the self-crystallization of Sb clusters observed in earlier simulations, we derive a hypothesis on quantum dot emergence from the subsurface based on sputtering. The results not only elucidate the dominant role of surface composition in driving compositional morphology, but also quantify fundamental ion-surface interactions attributed to the compositional depth profile.Ope

Podcasting from PowerPoint Made Easy for Faculty

Student demand, institutional support, and evidence of quality learning through web-based instruction should encourage faculty to experiment with alternative methods of delivering instruction. The authors developed a procedure to produce and deliver classroom lecture material by narrating PowerPoint presentations and converting to podcasts. This procedure requires little to no technical support, even for the technologically impaired, and costs less than $100 in equipment and software combined. It is an example of the many alternative distance education options available to educators today