163 research outputs found
An Examination of Musical Pitch/Color Correspondence in Music, Arts, And Non-arts Students and Adults
Chromesthesia is the involuntary combination of a visual color response to a musical stimulus. Previous research has associated the presence of absolute pitch with color responses to musical pitch; however, recent studies indicated that color associations were also made amongst those who did not possess absolute pitch. Eighty-four participants to various extent and of varying ages representing backgrounds in music and in arts (as well as those with neither background) took part in a series of experiments to determine if a color/music pitch connection was prevalent in their responses. Additionally, participants were tested individually regarding the presence of consistent visual color associations when applied to musical pitch as well as the presence of consistent musical pitch associations when applied to visual color. The results of this research indicated that while these color associations were not wholly universal, there were certain systemic similarities for many of these colors and musical pitches. The application of these similarities might prove successful in any number of diverse musical settings
Fano-like anti-resonances in strongly coupled binary Coulomb systems
Molecular Dynamics (MD) simulations of a strongly coupled binary ionic
mixture have revealed the appearance of sharp minima in the species resolved
dynamical density fluctuation spectra. This phenomenon is reminiscent of the
well-known Fano anti-resonance, occurring in various physical processes. We
give a theoretical analysis using the Quasi Localized Charge Approximation, and
demonstrate that the observed phenomenon in the equilibrium spectrum is a novel
manifestation of the Fano mechanism, that occurs at characteristic frequencies
of the system different from the conventional classical Fano frequencies
Enteral vancomycin to control severe methicillin-resistant Staphylococcus aureus infections in the intensive care unit
TheDynamical Structure Functions of Strongly Coupled Binary Charged Systems:
Thesis advisor: Gabor J. KalmanMixtures of charged particles, where the components have different charge numbers (Z_A ), masses (m_A ) and densities (n_A ), with A = 1, 2 denoting the components, occur in Nature in a great variety. To be sure, even the simplest plasmas are necessarily multicomponent systems, consisting of negative and positive charges. This feature is, however, obscured within the centrally important and popular OCP (one component plasma) or jellium models, where the role of one of the components is reduced to providing a neutralizing background. When this background is inert, one is led to the Coulomb OCP model, while when the background is polarizable (such as an electron gas surrounding heavy particles), to a Yukawa OCP (YOCP), with a screened Yukawa potential replacing the Coulomb potential between the dynamically active particles. There are, however situations of physical importance, where the OCP description is inadequate and a genuine two component description of a plasma composed of two species is required. This Thesis focuses on the study of the dynamics of many-body systems consisting of two components of like charges (all the Z_A -s being of the same signature) in a neutralizing background. The methodology is based upon parallel attacks through theoretical analysis and Molecular Dynamics (MD) simulations, the latter yielding the capability of instant verification of the former. The investigation involves the study of the partial (i.e. species by species) structure functions S_AB (k, ω) and current-current correlation functions L_AB (k, ω). The Fluctuation–Dissipation Theorem (FDT) con- nects these quantities to the total and partial response functions χ_AB (k, ω) (matrices in species space), which are instrumental in the description of the collective mode excitations of the system. This analysis has revealed an entirely novel feature: both S_11 (k, ω) and S_22 (k, ω) exhibit very sharp and deep (several orders of magnitude) minima in the strongly coupled liquid phase at robust characteristic frequencies of the system, which are virtually coupling independent. The FDT then demands that these anti-resonances show up as well in the imaginary part of the partial density response function χ_AB (k, ω). Our theoretical analysis, based on the Quasi-Localized Charge Approximation (QLCA), has confirmed that this is indeed the case. These anti-resonant frequencies being related to the dissipative part of the response, require a physical description of the principal source of dissipation. This has been identified as the inter-species momentum transfer, governed by drag between the microscopic current fluctuations of the two species. The description of this effect was incorporatedv in the QLCA formalism, making it possible to derive a closed analytic representation of the fluctuation spectra in the frequency domain of interest and compare them with the results of the MD simulations. Other important novel concepts, such as the idea of coupling dependent effective mass, fast vs. slow sound, the mechanism of tran- sition from short-range to long-range interaction have been identified and analyzed. Furthermore, the investigation of the dynamics has led to the first comprehensive description of the mode structures of classical binary Coulomb and Yukawa mixtures at arbitrary coupling values, which has been a longstanding problem in statistical plasma physics. Focusing on the longitudinal excitations, we describe the transition from weak coupling (where one is acquainted with the RPA result yielding only the single plasmon mode in the Coulomb case or a single acoustic mode in the Yukawa case) to strong coupling, with a doublet of modes that arise from the complex rel- ative motion between the two components, as affected by the interaction with the background.Thesis (PhD) — Boston College, 2019.Submitted to: Boston College. Graduate School of Arts and Sciences.Discipline: Physics
Is the Vlasov equation valid for Yukawa plasmas?
We analyze the Vlasov dispersion relation for Yukawa plasmas in three
dimensions for the purpose of identifying coupling parameter domains where the
Vlasov approach is justified and the existence of a well-developed RPA type
collective excitation is allowed. We establish a rigorous lower bound for the
coupling parameter, below which there can be no real solution to the Vlasov
dispersion relation. In the coupling domain, where weakly damped solutions do
exist, we have focused on the long-wavelength acoustic regime where we
establish more restrictive estimates for the lower bound of the coupling
parameter. We also derive a general formula for the corresponding acoustic
phase velocity, valid over a wide range of coupling parameter/screening
parameter ratios above the lower bound. We conclude that the Vlasov approach is
tenable only above a critical coupling value. Comparison with Molecular
Dynamics simulation results further highlights the limitations of the Vlasov
approximation for weakly coupled Yukawa plasmas
The approach to typicality in many-body quantum systems
The recent discovery that for large Hilbert spaces, almost all (that is,
typical) Hamiltonians have eigenstates that place small subsystems in thermal
equilibrium, has shed much light on the origins of irreversibility and
thermalization. Here we give numerical evidence that many-body lattice systems
generically approach typicality as the number of subsystems is increased, and
thus provide further support for the eigenstate thermalization hypothesis. Our
results indicate that the deviation of many-body systems from typicality
decreases exponentially with the number of systems. Further, by averaging over
a number of randomly-selected nearest-neighbor interactions, we obtain a
power-law for the atypicality as a function of the Hilbert space dimension,
distinct from the power-law possessed by random Hamiltonians.Comment: 6 pages, 2 png figures, revtex
Gut overgrowth harms the critically ill patient requiring treatment on the intensive care unit
Overgrowth is defined as ≥105 potential pathogens per ml of saliva and/or per g of faeces. There are six \u27normal\u27 potential pathogens carried by healthy individuals and nine \u27abnormal\u27 potential pathogens carried by individuals with underlying disease both chronic and acute. Surveillance cultures of throat and/or rectum are required to identify overgrowth of \u27normal\u27 and/or \u27abnormal\u27 potential pathogens. There is a qualitative and quantitative relationship between surveillance samples and diagnostic samples of tracheal aspirate and blood, i.e., as soon as potential pathogens reach overgrowth concentrations in the surveillance samples, the diagnostic samples become positive for identical potential pathogens. Digestive tract decontamination aims at the eradication of overgrowth in order to prevent severe infections of lower airways and blood. Parenteral cefotaxime controls overgrowth of \u27normal\u27 bacteria, and enteral polyenes control overgrowth of \u27normal\u27 Candida species. Enteral polymyxin and tobramycin (with or without) vancomycin control \u27abnormal\u27 overgrowth
Withholding selective decontamination of the digestive tract from critically ill patients must now surely be ethically questionable given the vast evidence base
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