Heidegger and Gadamer's appropriation of Aristotelian Phronesis

La présente étude se veut un examen de l’interprétation de la phronesis chez deux grands penseurs allemands du vingtième siècle, soit Martin Heidegger et Hans-Georg Gadamer. La motivation de ce projet découle d’un intérêt marqué pour l’étude de modèles alternatifs à la pensée technoscientifique de la connaissance. Considérant que Heidegger et Gadamer ont entrepris une importante réappropriation de la phronesis, nous avons jugé intéressant d’analyser leur pensée sous cet angle. Notre but est de mettre en relief les raisons qui ont poussé Heidegger et Gadamer à se tourner vers le concept de la phronesis et par la suite de tirer au clair les implications de cette réappropriation du concept aristotélicien au sein de leurs philosophies respectives. Cette étude est divisée en deux chapitres, traitant de la réappropriation de la phronesis chez Heidegger et Gadamer respectivement. Le premier chapitre porte sur l’interprétation heideggérienne de la phronesis en portant une attention particulière sur les cours maintenant publiés du plus jeune Heidegger. Dans le deuxième chapitre, nous traitons également de la réappropriation de la phronesis, mais cette fois, chez Gadamer afin de mettre en relief l’intérêt que présente la phronesis aristotélicienne pour l’herméneutique, mais aussi pour l’éthique de Gadamer. La dernière partie de ce chapitre propose une analyse comparative entre l’interprétation heideggérienne et gadamérienne de la phronesis. Notre étude veut montrer que Gadamer a suivi de près l’interprétation heideggérienne du concept aristotélicien de la phronesis, mais qu’il a aussi su s’en distinguer dans sa quête d’une conception plus authentique des sciences humaines, de l’herméneutique et de l’éthique.The present study aims at examining the interpretation of phronesis conducted by two central figures in twentieth-century German philosophy, namely Martin Heidegger and his student Hans-Georg Gadamer. The impetus for the following project comes from a general interest in the study of the alternatives to the technoscientific model of knowledge. Seeing as both philosophers took up the concept of phronesis, we deemed it as an interesting point of departure for an analysis of both their philosophies. In effect, we want to put into relief the reasons that motivated both thinkers to turn to the concept of phronesis and thereafter clarify the ramifications of their reappropriation of this Aristotelean concept in the development of their thought. The present study is divided in two chapters, each of which addresses the reappropriation of phronesis. The first chapter is an in-depth examination of the use of phronesis by Martin Heidegger, specifically with respect to his earlier lectures. The second chapter is also an examination of Gadamer’s reappropriation of phronesis in connection to both his conception of hermeneutics and ethics. The last section of this project is devoted to a comparative analysis between Heidegger and Gadamer’s reappropriation of phronesis. Our study reveals that Gadamer followed closely the lead of his teacher, while at the same time making the concept of phronesis his own by integrating it in his quest for a more genuine conception of the Geisteswissenschaften, and in his substantial development of hermeneutics

An Enhanced Indirect Video-Based Measurement Procedure for Dynamic Structural System Identification Applications

A video-based indirect sensing procedure for dynamic identification purposes is presented. To overcome major limitations of video-based methods in real on-site measurements, a novel three step pre-modification, magnification, post-modification process is developed. This process includes revision of the initial input video record in order to delete disturbing objects, utilizing a magnification method to filter the frequency content of the monitored motion and using a revision step for elimination of noises generated during magnification process. Finally, a set of digital signal and image processing analyses are performed on the modified video using virtual visual sensor technology. Based on the results of this research, motion signals of the monitored object are detected. The proposed approach has been used for identification of dynamic characteristics of two historic masonry minarets in Istanbul. Results shows that the proposed procedure is able to assess the dynamic characteristics of the monitored structure with a high-level of accuracy

Particle swarm optimization of friction tuned mass dampers subjected to ground motion records

Friction tuned mass dampers (FTMDs) are widely used to control the displacement of structures located in seismically active areas. Typically, the frequency and friction ratios of FTMDs are tuned up during design, but this task is complex if real ground motion records are considered. This article proposes a novel and accurate approach to calculate optimum parameters of FTMDs for controlling the displacements of both single degree of freedom (SDOF) systems and multi-story structural frames subjected to real ground motion records. In this study, the SDOF displacement and two FTMD parameters (frequency ratio and friction ratio) are first optimized simultaneously using a Particle Swarm Optimization (PSO) algorithm. A series of sensitivity analyses are then carried out to examine the effect of different structural features (damper movement, variations of optimized parameters and damping) on the optimized SDOF displacements and FTMD parameters given by the PSO. It is shown that, compared to a more established method available in the literature, the PSO algorithm reduces the SDOF displacements by an additional 21% on average. The PSO is then used to obtain optimum parameters of FTMDs and TMDs connected to four moment-resisting frames, and the results from the frames are compared to those from equivalent SDOF systems. This article contributes towards providing more suitable optimization tools for structures fitted with FTMDs, which in turn can lead to more efficient design methods for dampers

Statistical mechanics of columnar DNA assemblies

Many physical systems can be mapped onto solved or "solvable" models of magnetism. In this work, we have mapped the statistical mechanics of columnar phases of ideally helical rigid DNA -- subject to the earlier found unusual, frustrated pair potential [A. A. Kornyshev and S. Leikin, J. Chem. Phys. 107, 3656 (1997)] -- onto an exotic, unknown variant of the XY model on a fixed or restructurable lattice. Here the role of the 'spin' is played by the azimuthal orientation of the molecules. We have solved this model using a Hartree-Fock approximation, ground state calculations, and finite temperature Monte Carlo simulations. We have found peculiar spin order transitions, which may also be accompanied by positional restructuring, from hexagonal to rhombohedric lattices. Some of these have been experimentally observed in dense columnar aggregates. Note that DNA columnar phases are of great interest in biophysical research, not only because they are a useful in vitro tool for the study of DNA condensation, but also since these structures have been detected in living matter. Within the approximations made, our study provides insight into the statistical mechanics of these systems.Comment: 19 pages, 18 figure

Gold and colloidal gold surface influence on dna conformational change

DNA conformational changes caused by gold and colloidal gold surface have been studied by surface enhanced infrared spectroscopy (SEIRA), spectroscopy of plasmon resonance (SPR), atomic force microscopy (AFM) and principal component analysis. Experimental data have shown that DNA conformation is slightly influenced by gold surface, while it is strongly altered by colloidal gold. Spectroscopic features of DNA-colloidal gold system have shown that the intensity of the asymmetric PO₂– band at 1240 cm⁻¹ decreases by two times, and that of symmetric band at 1090 cm⁻¹ decreases by 2.4 times whereas the halfwidth of phosphate bands increases by 35–40 cm⁻¹; a frequency shift of asymmetric band position from 1240 to 1246 cm⁻¹ and a symmetric band from 1090 to 1106 cm⁻¹ has been observed. It was shown that intensity variation and shift of DNA base vibrations together with the broadening of OH, NH, and CH stretching vibrations occur due to DNA conformational changes and the redistribution of the H-bonding network. A supposition about DNA condensation by colloidal gold was made. SEIRA and AFM data have showed major DNA structural changes occurred on gold colloidal particles. It was found that all the spectral features are more prominent for DNA–colloidal gold system deposited on gold substrate than on CaF₂ substrate

Structural characterization of cationic lipid–tRNA complexes

Despite considerable interest and investigations on cationic lipid–DNA complexes, reports on lipid–RNA interaction are very limited. In contrast to lipid–DNA complexes where lipid binding induces partial B to A and B to C conformational changes, lipid–tRNA complexation preserves tRNA folded state. This study is the first attempt to investigate the binding of cationic lipid with transfer RNA and the effect of lipid complexation on tRNA aggregation and condensation. We examine the interaction of tRNA with cholesterol (Chol), 1,2-dioleoyl-3-trimethylammonium-propane (DOTAP), dioctadecyldimethylammoniumbromide (DDAB) and dioleoylphosphatidylethanolamine (DOPE), at physiological condition, using constant tRNA concentration and various lipid contents. FTIR, UV-visible, CD spectroscopic methods and atomic force microscopy (AFM) were used to analyze lipid binding site, the binding constant and the effects of lipid interaction on tRNA stability, conformation and condensation. Structural analysis showed lipid–tRNA interactions with G–C and A–U base pairs as well as the backbone phosphate group with overall binding constants of KChol = 5.94 (± 0.8) × 104 M–1, KDDAB = 8.33 (± 0.90) × 105 M–1, KDOTAP = 1.05 (± 0.30) × 105 M–1 and KDOPE = 2.75 (± 0.50) × 104 M–1. The order of stability of lipid–tRNA complexation is DDAB > DOTAP > Chol > DOPE. Hydrophobic interactions between lipid aliphatic tails and tRNA were observed. RNA remains in A-family structure, while biopolymer aggregation and condensation occurred at high lipid concentrations

Structural characterization of cationic lipid–tRNA complexes

Despite considerable interest and investigations on cationic lipid–DNA complexes, reports on lipid–RNA interaction are very limited. In contrast to lipid–DNA complexes where lipid binding induces partial B to A and B to C conformational changes, lipid–tRNA complexation preserves tRNA folded state. This study is the first attempt to investigate the binding of cationic lipid with transfer RNA and the effect of lipid complexation on tRNA aggregation and condensation. We examine the interaction of tRNA with cholesterol (Chol), 1,2-dioleoyl-3-trimethylammonium-propane (DOTAP), dioctadecyldimethylammoniumbromide (DDAB) and dioleoylphosphatidylethanolamine (DOPE), at physiological condition, using constant tRNA concentration and various lipid contents. FTIR, UV-visible, CD spectroscopic methods and atomic force microscopy (AFM) were used to analyze lipid binding site, the binding constant and the effects of lipid interaction on tRNA stability, conformation and condensation. Structural analysis showed lipid–tRNA interactions with G–C and A–U base pairs as well as the backbone phosphate group with overall binding constants of KChol = 5.94 (± 0.8) × 104 M–1, KDDAB = 8.33 (± 0.90) × 105 M–1, KDOTAP = 1.05 (± 0.30) × 105 M–1 and KDOPE = 2.75 (± 0.50) × 104 M–1. The order of stability of lipid–tRNA complexation is DDAB > DOTAP > Chol > DOPE. Hydrophobic interactions between lipid aliphatic tails and tRNA were observed. RNA remains in A-family structure, while biopolymer aggregation and condensation occurred at high lipid concentrations

A Hybrid Least Squares and Principal Component Analysis Algorithm for Raman Spectroscopy

Raman spectroscopy is a powerful technique for detecting and quantifying analytes in chemical mixtures. A critical part of Raman spectroscopy is the use of a computer algorithm to analyze the measured Raman spectra. The most commonly used algorithm is the classical least squares method, which is popular due to its speed and ease of implementation. However, it is sensitive to inaccuracies or variations in the reference spectra of the analytes (compounds of interest) and the background. Many algorithms, primarily multivariate calibration methods, have been proposed that increase robustness to such variations. In this study, we propose a novel method that improves robustness even further by explicitly modeling variations in both the background and analyte signals. More specifically, it extends the classical least squares model by allowing the declared reference spectra to vary in accordance with the principal components obtained from training sets of spectra measured in prior characterization experiments. The amount of variation allowed is constrained by the eigenvalues of this principal component analysis. We compare the novel algorithm to the least squares method with a low-order polynomial residual model, as well as a state-of-the-art hybrid linear analysis method. The latter is a multivariate calibration method designed specifically to improve robustness to background variability in cases where training spectra of the background, as well as the mean spectrum of the analyte, are available. We demonstrate the novel algorithm’s superior performance by comparing quantitative error metrics generated by each method. The experiments consider both simulated data and experimental data acquired from in vitro solutions of Raman-enhanced gold-silica nanoparticles

Phase Behavior of Columnar DNA Assemblies

The pair interaction between two stiff parallel linear DNA molecules depends not only on the distance between their axes but on their azimuthal orientation. The positional and orientational order in columnar B-DNA assemblies in solution is investigated, based on the DNA-DNA electrostatic pair potential that takes into account DNA helical symmetry and the amount and distribution of adsorbed counterions. A phase diagram obtained by lattice sum calculations predicts a variety of positionally and azimuthally ordered phases and bundling transitions strongly depending on the counterion adsorption patterns.Comment: 4 pages, 3 figures, submitted to PR

The Persistence Length of a Strongly Charged, Rod-like, Polyelectrolyte in the Presence of Salt

The persistence length of a single, intrinsically rigid polyelectrolyte chain, above the Manning condensation threshold is investigated theoretically in presence of added salt. Using a loop expansion method, the partition function is consistently calculated, taking into account corrections to mean-field theory. Within a mean-field approximation, the well-known results of Odijk, Skolnick and Fixman are reproduced. Beyond mean-field, it is found that density correlations between counterions and thermal fluctuations reduce the stiffness of the chain, indicating an effective attraction between monomers for highly charged chains and multivalent counterions. This attraction results in a possible mechanical instability (collapse), alluding to the phenomenon of DNA condensation. In addition, we find that more counterions condense on slightly bent conformations of the chain than predicted by the Manning model for the case of an infinite cylinder. Finally, our results are compared with previous models and experiments.Comment: 13 pages, 2 ps figure