Macroscopically Dissipative Systems with Underlying Microscopic Dynamics : Properties and Limits of Measurement

While some of the deepest results in nature are those that give explicit bounds between important physical quantities, some of the most intriguing and celebrated of such bounds come from fields where there is still a great deal of disagreement and confusion regarding even the most fundamental aspects of the theories. For example, in quantum mechanics, there is still no complete consensus as to whether the limitations associated with Heisenberg's Uncertainty Principle derive from an inherent randomness in physics, or rather from limitations in the measurement process itself, resulting from phenomena like back action. Likewise, the second law of thermodynamics makes a statement regarding the increase in entropy of closed systems, yet the theory itself has neither a universally-accepted definition of equilibrium, nor an adequate explanation of how a system with underlying microscopically Hamiltonian dynamics (reversible) settles into a fixed distribution.

Motivated by these physical theories, and perhaps their inconsistencies, in this thesis we use dynamical systems theory to investigate how the very simplest of systems, even with no physical constraints, are characterized by bounds that give limits to the ability to make measurements on them. Using an existing interpretation, we start by examining how dissipative systems can be viewed as high-dimensional lossless systems, and how taking this view necessarily implies the existence of a noise process that results from the uncertainty in the initial system state. This fluctuation-dissipation result plays a central role in a measurement model that we examine, in particular describing how noise is inevitably injected into a system during a measurement, noise that can be viewed as originating either from the randomness of the many degrees of freedom of the measurement device, or of the environment. This noise constitutes one component of measurement back action, and ultimately imposes limits on measurement uncertainty. Depending on the assumptions we make about active devices, and their limitations, this back action can be offset to varying degrees via control. It turns out that using active devices to reduce measurement back action leads to estimation problems that have non-zero uncertainty lower bounds, the most interesting of which arise when the observed system is lossless. One such lower bound, a main contribution of this work, can be viewed as a classical version of a Heisenberg uncertainty relation between the system's position and momentum. We finally also revisit the murky question of how macroscopic dissipation appears from lossless dynamics, and propose alternative approaches for framing the question using existing systematic methods of model reduction.

Observation of ultrafast carrier dynamics in amorphous Ge2Sb2Te5 films induced by femtosecond laser pulses

The femtosecond pump-probe technique was used to study the carrier dynamics of amorphous Ge2Sb2Te5 films. With carrier density at around 10(20)-10(21) cm(-3), carriers were excited within 1 ps and recovered to the initial state for less than 3 ns. On the picosecond time scale, the carrier relaxation consists of two components: a fast process within 5 ps and a slow process after 5 ps. The relaxation time of the fast component is a function of carrier density, which increases from 1.9 to 4.3 ps for the carrier density changing from 9.7x10(20) cm(-3) to 3.1x10(21) cm(-3). A possible interpretation of the relaxation processes is elucidated. In the first 5 ps the relaxation process is dominated by an intraband carrier relaxation and the carrier trapping. It is followed by a recombination process of trapped carriers at later delay time. (c) 2007 American Institute of Physics.

Studying adsorbent dynamics on a quartz crystal resonator using its nonlinear electrical response

The quartz crystal resonator has been traditionally employed in studying surface-confined physisorbed films and particles by measuring dissipation and frequency shifts. However, theoretical interpretation of the experimental observations is often challenged due to limited understanding of physical interaction mechanisms at the interfaces involved. Here we model a physisorbed interaction between particles and gold electrode surface of a quartz crystal and demonstrate how the nonlinear modulation of the electric response of the crystal due to the nonlinear interaction forces may be used to study the dynamics of the particles. In particular, we show that the graphs of the deviation in the third Fourier harmonic response versus oscillation amplitude provide important information about the onset, progress and nature of sliding of the particles. The graphs also present a signature of the surface-particle interaction and could be used to estimate the interaction energy profile. Interestingly, the insights gained from the model help to explain some of the experimental observations with physisorbed streptavidin-coated polystyrene microbeads on quartz resonators. © 2012 Elsevier B.V. All rights reserved.

NMR Spectra of polyimides: Interpretation and local chain motion study

Three kinds of high-performance polyimides 1 (poly(ketone-imide) PKI), 2 (poly(ether-imide) PEI) and 3 (poly(oxy-imide) POI) were studied using nuclear magnetic resonance (NMR). The NMR spectra of the polyimides were assigned according to the comprehensive consideration of the substitution effect of different substituting groups, viz. distortionless enhancement by polarization transfer (DEPT), no nuclear Overhauser effect (NNE), analysis of relaxation time, and two-dimensional correlated spectroscopy (COSY) techniques. The structural units of these three polyimides were determined. Carbon-13 and proton relaxation times for PEI and PKI were interpreted in terms of segmental motion characterized by the sharp cutoff model of Jones and Stockmayer (JS model) and anisotropic group rotation such as phenyl group rotation and methyl group rotation. Correlation times for the main-chain motion are in the tens of picosecond range which indicates the high flexibility of polyimide chains. Correlation times for phenyl group and methyl group rotations are more than 1 order of magnitude lower and approximately 1 order of magnitude higher than that of the main chain, respectively.

利用宽频带台阵资料研究华北地区地壳及上地幔间断面结构

Intense tectonic renovation has occurred in the eastern continent of china since Mesozoic, as evidenced by the high heat flow, widespread magma extrusion and volcanic activities, and development of large sedimentary basins. To explain the cause and mechanism for the tectonic process in this period, some researchers have put forward various models, such as mantle plume, subduction of the Pacific slab, Yangtze Block-North China Block collision, etc. Their seismological evidence, however, is still scarce..During the period from 2000 to 2003, large temporary seismic arrays were established in North China by the Institute of the Geology and Geophysics, Chinese Academy of Sciences. Total 129 portable seismic stations were linearly emplaced across the western and eastern boundaries of the Bohai Bay Basin, and accumulated a large amount of high-quality data. Moreover, abundant data were also collected at the capital digital seismic network established in the ninth five-year period of national economic and social development. These provide an unprecedented opportunity for us to study the deep structure and associated geodynamic mechanism of lithospheric processes in North China using seismological techniques.Seismology is a kind of observation-based science. The development of seismic observations greatly promotes the improvement of seismologic theory and methodology. At the beginning of this thesis, I review the history of seismic observation progress, and present some routine processing techniques used in the array seismology. I also introduce two popular seismic imaging methods (receiver function method and seismic tomography).Receiver function method has been widely used to study the crustal and upper mantle structures, and many relevant research results have been published. In this thesis I elaborate the theory of this method, including the basic concept of receiver functions and the methodology for data pre-processing, stacking and migration. I also address some problems often encountered in practical applications of receiver function imaging.By using the teleseismic data collected at the temporary seismic arrays in North China, in particular, the traveltime information of P-to-S conversion and multiple reverberations of the Moho discontinuity, I obtain the distributions of the crustal thickness and the poisson ratio at the northwest boundary area of the Bohai Bay Basin and discuss the geological implications of the results.Through detailed intestigations on the crustal structural feature around the middle part of the Tanlu fault, considerable disparity in poisson ratios is found in the western and eastern sides of the Tanlu fault. Moreover, an obvious Moho offset is coincidently observed at the same surface location. A reasonable density model for the Tanlu fault area is also derived by simulating the observed gravity variations. Both receiver function study and gravity anomaly modeling suggest that the crustal difference between the western and eastern sides of the Tanlu fault is mainly resulted from their different compositions.With common conversion point imaging of receiver functions, I estimate the depths of the upper and lower boundaries of the mantle transition zone, i.e., the 410 and 660 km discontinuities, beneath most part of the North China continent The thickness of the transition zone (TTZ) in the study area is calculated by subtracting the depth of .410 km discontinuity from that of the 660km discontinuity. The resultant TTZ is 10-15 km larger in the east than in the west of the study area. Phase transitions at the 410 km and the 660 km discontinuities are known to have different Clapeyron slopes. Therefore, the TTZ is sensitive to the temperature changes in the transition zone. Previous studies have shown that the TTZ would be smaller in the mantle plume areas and become larger when the remnants of subducted slabs are present The hypothesis of mantle plume cannot give a reasonable interpretation to the observed TTZ beneath North China, Instead, the receiver function imaging results favor a dynamic model that correlates the thermal structure of the mantle transition zone and associated upper mantle dynamics of North China to the Pacific plate subduction process.

The ‘Faust’ or ’Lucifer’ Sonata? On Liszt’s idea of programme music as exemplifi ed by his Piano Sonata in B minor

The musicological tradition places Liszt’s Sonata in B minor within the sphere of compositions inspired by the Faustian myth. Its musical material, its structure and its narrative exhibit certain similarities to the ‘Faust’ Symphony. Yet there has appeared a diff erent and, one may say, a rival interpretation of Sonata in B minor. What is more, it is well-documented from both a musical and a historical point of view. It has been presented by Hungarian pianist and musicologist Tibor Szász. He proposes the thesis that the Sonata in B minor has been in fact inspired by Milton’s Paradise Lost, with its three protagonists: Adam, Satan and Christ. He fi nds their illustrations and even some key elements of the plot in the Sonata’s narrative. But yet Milton’s Paradise Lost and Goethe’s Faust are both stories of the Fall and Salvation, of the cosmic struggle between good and evil. The triads of their protagonists – Adam and Eve, Satan, and Christ; Faust, Mephisto and Gretchen – are homological. Thus both interpretations of the Sonata, the Goethean and the Miltonian, or, in other words, the Faustian and the Luciferian, are parallel and complementary rather than rival. It is also highly probable that both have had their impact on the genesis of the Sonata in B minor.

EXPERIMENTAL INVESTIGATION OF LINEAR BUBBLE DYNAMICS IN A VISCOELASTIC XANTHAN GEL

Oceanic bubble plumes caused by ship wakes or breaking waves disrupt sonar communi- cation because of the dramatic change in sound speed and attenuation in the bubbly fluid. Experiments in bubbly fluids have suffered from the inability to quantitatively characterize the fluid because of continuous air bubble motion. Conversely, single bubble experiments, where the bubble is trapped by a pressure field or stabilizing object, are limited in usable frequency range, apparatus complexity, or the invasive nature of the stabilizing object (wire, plate, etc.). Suspension of a bubble in a viscoelastic Xanthan gel allows acoustically forced oscilla- tions with negligible translation over a broad frequency band. Assuming only linear, radial motion, laser scattering from a bubble oscillating below, through, and above its resonance is measured. As the bubble dissolves in the gel, different bubble sizes are measured in the range 240 – 470 μm radius, corresponding to the frequency range 6 – 14 kHz. Equalization of the cell response in the raw data isolates the frequency response of the bubble. Compari- son to theory for a bubble in water shows good agreement between the predicted resonance frequency and damping, such that the bubble behaves as if it were oscillating in water.

Temporal Dynamics of Decision-Making during Motion Perception in the Visual Cortex

How does the brain make decisions? Speed and accuracy of perceptual decisions covary with certainty in the input, and correlate with the rate of evidence accumulation in parietal and frontal cortical "decision neurons." A biophysically realistic model of interactions within and between Retina/LGN and cortical areas V1, MT, MST, and LIP, gated by basal ganglia, simulates dynamic properties of decision-making in response to ambiguous visual motion stimuli used by Newsome, Shadlen, and colleagues in their neurophysiological experiments. The model clarifies how brain circuits that solve the aperture problem interact with a recurrent competitive network with self-normalizing choice properties to carry out probablistic decisions in real time. Some scientists claim that perception and decision-making can be described using Bayesian inference or related general statistical ideas, that estimate the optimal interpretation of the stimulus given priors and likelihoods. However, such concepts do not propose the neocortical mechanisms that enable perception, and make decisions. The present model explains behavioral and neurophysiological decision-making data without an appeal to Bayesian concepts and, unlike other existing models of these data, generates perceptual representations and choice dynamics in response to the experimental visual stimuli. Quantitative model simulations include the time course of LIP neuronal dynamics, as well as behavioral accuracy and reaction time properties, during both correct and error trials at different levels of input ambiguity in both fixed duration and reaction time tasks. Model MT/MST interactions compute the global direction of random dot motion stimuli, while model LIP computes the stochastic perceptual decision that leads to a saccadic eye movement.

BACH TO BASICS: A PERFORMANCE STUDY OF THE SUITES FOR SOLO CELLO BY JOHANN SEBASTIAN BACH, BWV 1007-1012

This dissertation project focuses on J.S. Bach's Six Suites and explores the ideology of the Suites as etudes versus concert pieces. It is my belief that the evolution of the rank of the Suites in a cellist's repertoire today represents more than just historical coincidence. My premise is that the true genius of the Suites lies in their dual role as !&I efficient teaching pieces and superior performance works. Consequently, the maximum use of Bach's Six Suites as pedagogical material heightens both technical ability and deeper appreciation of the art. The dual nature of the Suites must always be emphasized: not only do these pieces provide innumerable opportunities for building cello technique, but they also offer material for learning the fundamentals of melody, harmony, dynamics, phrasing and texture. It is widely accepted among academic musicians that Bach's keyboard music serves as perfect compositions -- the model for music theory, music form and music counterpoint. I argue that we should employ the Cello Suites to this same end. The order in which the Suites are presented was deliberately chosen to highlight the contrasts in the pieces. Because the technical demands of each suite grow progressively from the previous one, they were performed non-consecutively in order to balance the difficulty and depth of each recital. The first compact disc consists of the Third Suite in C Major and Fifth Suite in C minor (with scordatura tuning), emphasizing the parallel keys. The Second Suite in D Minor and the Fourth Suite in E-flat Major comprises the compact disc. Finally, in the third compact disc, the First Suite in G Major and the Sixth Suite in D Major (composed for the five string cello piccola, but played here on a four-string cello) highlights the progression of the Suites.

The Effects of Geography, Environment and Phylogeny on Community Assembly and Gene Flow Dynamics

It is increasingly evident that evolutionary processes play a role in how ecological communities are assembled. However the extend to which evolution influences how plants respond to spatial and environmental gradients and interact with each other is less clear. In this dissertation I leverage evolutionary tools and thinking to understand how space and environment affect community composition and patterns of gene flow in a unique system of Atlantic rainforest and restinga (sandy coastal plains) habitats in Southeastern Brazil.

In chapter one I investigate how space and environment affect the population genetic structure and gene flow of Aechmea nudicaulis, a bromeliad species that co-occurs in forest and restinga habitats. I genotyped seven microsatellite loci and sequenced one chloroplast DNA region for individuals collected in 7 pairs of forest / restinga sites. Bayesian genetic clustering analyses show that populations of A. nudicaulis are geographically structured in northern and southern populations, a pattern consistent with broader scale phylogeographic dynamics of the Atlantic rainforest. On the other hand, explicit migration models based on the coalescent estimate that inter-habitat gene flow is less common than gene flow between populations in the same habitat type, despite their geographic discontinuity. I conclude that there is evidence for repeated colonization of the restingas from forest populations even though the steep environmental gradient between habitats is a stronger barrier to gene flow than geographic distance.

In chapter two I use data on 2800 individual plants finely mapped in a restinga plot and on first-year survival of 500 seedlings to understand the roles of phylogeny, functional traits and abiotic conditions in the spatial structuring of that community. I demonstrate that phylogeny is a poor predictor of functional traits in and that convergence in these traits is pervasive. In general, the community is not phylogenetically structured, with at best 14% of the plots deviating significantly from the null model. The functional traits SLA, leaf dry matter content (LDMC), and maximum height also showed no clear pattern of spatial structuring. On the other hand, leaf area is strongly overdispersed across all spatial scales. Although leaf area overdispersion would be generally taken as evidence of competition, I argue that interpretation is probably misleading. Finally, I show that seedling survival is dramatically increased when they grow shaded by an adult individual, suggesting that seedlings are being facilitated. Phylogenetic distance to their adult neighbor has no influence on rates of survival though. Taken together, these results indicate that phylogeny has very limited influence on the fine scale assembly of restinga communities.

High School Choral Students' Perceptions of Choral Music Experience

The purpose of this study is to explore high school students' perceptions of their choral experiences, providing an understanding of students' ongoing perspectives of choral experience. Specifically, how have these experiences influenced the formation of their musical identities as members of a choral ensemble? The researcher collected data from the three participants during a full school year. The participants were current students in the researcher's advanced choral ensemble. Through axial coding, three themes emerged: musical interpretation, attitude, and group efficacy. The study revealed that experienced choral students have well-informed musical perspectives that influence their choral experiences. Implications for music education include using students' perspectives for creating rehearsal strategies, planning and programming performances, and fostering a nurturing learning atmosphere. Suggestions for further research include comparing experienced students to non-experienced students, comparing ensembles with student-chosen repertoire to those with director-chosen repertoire, and further examining the impact of choral experience on musical identity.

Polish Violin Music in the 20th and 21st Century

The purpose of this dissertation is to promote Polish violin music written in the 20th and 21st Century. My recitals included many lesser-known compositions and composers which I strongly believe deserve to be better known and more often performed. The search and preparation of those pieces, for which recordings and music scores are not easily found, was a very exciting and stimulating process. Much Polish music written in the 20th and 21st Century is interesting, expressive, beautiful, and deserves to be more often performed. Performing 20th and 21st Century music opens new perspectives in two directions: musically and technically. Performer and listener are, in many cases, unbound from tonality. Composers are looking for new sonorities and exploring such performing techniques as varieties of harmonics, quarter tones, extreme dynamics, complex rhythms, and usage of a wide range of registers. An important part of Polish music is Polish folklore. The little town of Zakopane is known for Polish traditional clothing, food, architecture, dance and music. Also, most prominent Polish luthiers including Wojciech Topa, whose instrument I am playing, have been making their instruments in Zakopane. This little town in the Tatras Mountain has been an inspiration for many Polish artists including Iwaszkiewicz, Witkacy, Karłowicz, and Szymanowski. Those composers used such folklore elements as folk scales, popular tunes, and imitations of the sound of the folk band with characteristic folk dance rhythms. Other musical genres where folk elements are strongly present are the compositions dedicated to young musicians, with a specifically educational purpose. Among composers who wrote educational music were Grażyna Bacewicz, Witold Lutosławski, and Henryk Mikołaj Górecki. This approach makes the works more easily understood by young performers and, at the same time, broadens their understanding of Polish culture and prepares them for the challenges of contemporary music. This has been an exciting project for me because, on the one hand, it allowed me the challenge of performing compositions that are lesser-known and often consist of musical language new to me while, on the other, it brought me back to my roots and the country of my mother tongue.

Region-wide changes in marine ecosystem dynamics: state-space models to distinguish trends from step changes

Regime shifts are sudden changes in ecosystem structure that can be detected across several ecosystem components. The concept that regime shifts are common in marine ecosystems has gained popularity in recent years. Many studies have searched for the step-like changes in ecosystem state expected under a simple interpretation of this idea. However, other kinds of change, such as pervasive trends, have often been ignored. We assembled over 300 ecological time series from seven UK marine regions, covering two to three decades. We developed state-space models for the first principal component of the time series in each region, a common measure of ecosystem state. Our models allowed both trends and step changes, possibly in combination. We found trends in three of seven regions and step changes in two of seven regions. Gradual and sudden changes are therefore important trajectories to consider in marine ecosystems.

Restricted rotation dynamics and far-infrared spectra of liquid water governed by elastic interactions

A semi-phenomenological model describing wideband dielectric and far-infrared spectra of liquid water was proposed recently by the same authors [J. Mol. Struct. 606 (2002) 9], where a small dipole-moment component changing harmonically with time determines a weak absorption band (termed here the R-band) centred at the wavenumber v similar to 200 cm(-1). In the present work, a rough molecular theory of the R-band based on the concept of elastic interactions is given. Stretching and bending of hydrogen bonds cause restricted rotation (RR) of a polar water molecule in terms of a dimer comprising the H- bonded molecules. Analytical expression for the RR frequency nu(str) is derived as a function of the RR amplitude, geometrical parameters and force constants. The density g(nu(str)) of frequency distribution is shown to be centred in the R-band. The spectrum of the dipolar auto-correlation function calculated for this structural-dynamical model is found. A composite model comprising two intermolecular potentials is proposed, which yields for water a good description of the experimental wideband (from 0 to 1000 cm(- 1)) spectra of complex permittivity and of absorption coefficient. The presented interpretation of these spectra is based on a concept that water presents a two-component solution, with components differing by the types of molecular rotation. (C) 2003 Elsevier B.V. All rights reserved.

Confusing Culture and Politics: Ulster Scots Culture and Music

In Northern Ireland of the mid-1990s, many were caught off-guard by the comet-like arrival of a previously unarticulated Ulster Scots identity, replete with its own folk traditions. The article exploits the author’s position as Traditional Arts Officer of the Arts Council of Northern Ireland from 1998 until 2003 to offer an auto-ethnographic reflection on the literature on cultural politics in Northern Ireland since the outbreak of the Troubles, informed by extensive fieldwork with arts administrators and with contemporary Ulster Scots musicians. The article gives a close reading and historical contextualisation of the Ulster-Scots musical revue On Eagle's Wing, which was developed during this period. The article uses the concept of "suture" articulated by Lacan and developed by Laclau, Mouffe, and Žižek to explain both the potential for Ulster Scots culture to enter political discourse out of a seeming vacuum and its subsequent difficulties, offering an original interpretation of the role of culture in the contemporary trajectory of Northern Ireland politics.