La "imatge" de la caverna i la temptació constant de corregir Plató: Benjamin Jowett com a exemple

[cat] Les traduccions dels primers capítols del llibre VII de la República de Plató on apareix la famosa imatge de la caverna, εἰκών, presenten una sorprenent i intrigant varietat interpretativa: “al·legoria”, “mite”, “faula”, “paràbola”, “símil”, “comparació”... Aquest article, prenent com a exemple la notable fidelitat al text del traductor victorià de Plató, B. Jowett, i mitjançant una anàlisi rigorosa dels termes que acompanyen la imatge, manté la necessitat de no interpretar ni corregir en aquest cas el gran filòsof idealista o “ideocèntric”, assenyalant alhora, si el capteniment filològic és un altre, les contradiccions resultants i l’ús d’algun terme aliè al lèxic platònic com ara “al·legoria”.

Drag force and frictional resistances in vertically vibrated dense granular media

The objective of this thesis is to shed light on the vertical vibration of granular materials for potential interest in the power generation industry. The main focus is investigating the drag force and frictional resistance that influence the movement of a granular material (in the form of glass beads) contained in a vessel, which is subjected to sinusoidal oscillation. The thesis is divided into three parts: theoretical analysis, experiments and computer simulations. The theoretical part of this study presents the underlying physical phenomena of the vibration of granular materials. Experiments are designed to determine fundamental parameters that contribute to the behavior of vibrating granular media. Numerical simulations include the use of three different software applications: FLUENT, LS-DYNA and ANSYS Workbench. The goal of these simulations is to test theoretical and semiempirical models for granular materials in order to validate their compatibility with the experimental findings, to assist in predicting their behavior, and to estimate quantities that are hard to measure in laboratory.

Dynamic electrostatic force microscopy in liquid media

We present the implementation of dynamic electrostatic force microscopy in liquid media. This implementation enables the quantitative imaging of local dielectric properties of materials in electrolyte solutions with nanoscale spatial resolution. Local imaging capabilities are obtained by probing the frequency-dependent and ionic concentration-dependent electrostatic forces at high frequency (>1 MHz), while quantification of the interaction forces is obtained with finite-element numerical calculations. The results presented open a wide range of possibilities in a number of fields where the dielectric properties of materials need to be probed at the nanoscale and in a liquid environment.

Dynamic electrostatic force microscopy in liquid media

We present the implementation of dynamic electrostatic force microscopy in liquid media. This implementation enables the quantitative imaging of local dielectric properties of materials in electrolyte solutions with nanoscale spatial resolution. Local imaging capabilities are obtained by probing the frequency-dependent and ionic concentration-dependent electrostatic forces at high frequency (>1 MHz), while quantification of the interaction forces is obtained with finite-element numerical calculations. The results presented open a wide range of possibilities in a number of fields where the dielectric properties of materials need to be probed at the nanoscale and in a liquid environment.

Sensor Fusion of Proprioception, Force and Vision in Estimation and Robot

Sensor-based robot control allows manipulation in dynamic environments with uncertainties. Vision is a versatile low-cost sensory modality, but low sample rate, high sensor delay and uncertain measurements limit its usability, especially in strongly dynamic environments. Force is a complementary sensory modality allowing accurate measurements of local object shape when a tooltip is in contact with the object. In multimodal sensor fusion, several sensors measuring different modalities are combined to give a more accurate estimate of the environment. As force and vision are fundamentally different sensory modalities not sharing a common representation, combining the information from these sensors is not straightforward. In this thesis, methods for fusing proprioception, force and vision together are proposed. Making assumptions of object shape and modeling the uncertainties of the sensors, the measurements can be fused together in an extended Kalman filter. The fusion of force and visual measurements makes it possible to estimate the pose of a moving target with an end-effector mounted moving camera at high rate and accuracy. The proposed approach takes the latency of the vision system into account explicitly, to provide high sample rate estimates. The estimates also allow a smooth transition from vision-based motion control to force control. The velocity of the end-effector can be controlled by estimating the distance to the target by vision and determining the velocity profile giving rapid approach and minimal force overshoot. Experiments with a 5-degree-of-freedom parallel hydraulic manipulator and a 6-degree-of-freedom serial manipulator show that integration of several sensor modalities can increase the accuracy of the measurements significantly.

Investigating the spontaneous formation of SDS micelle in aqueous solution using a coarse-grained force field

A 1µs Molecular Dynamic simulation was performed with a realistic model system of Sodium Dodecyl Sulfate (SDS) micelles in aqueous solution, comprising of 360 DS-, 360 Na+ and 90000 water particles. After 300 ns three different micellar shapes and sizes 41, 68 and 95 monomers, were observed. The process led to stabilization in the total number of SDS clusters and an increase in the micellar radius to 2.23 nm, in agreement with experimental results. An important conclusion, is be aware that simulations employed in one aggregate, should be considered as a constraint. Size and shape distribution must be analyzed.

CARBOXYLATION OF SILVER NANOPARTICLES FOR THE IMMOBILIZATION OF β-GALACTOSIDASE AND ITS EFFICACY IN GALACTO-OLIGOSACCHARIDES PRODUCTION

The present study investigated the carboxylation of silver nanoparticles (AgNPs) by 1:3 nitric acid-sulfuric acid mixtures for immobilizing Aspergillus oryzae β-galactosidase. Carboxylated AgNPs retained 93% enzyme upon immobilization and the enzyme did not leach out appreciably from the modified nanosupport in the presence of 100 mmol L-1 NaCl. Atomic force micrograph revealed the binding of β-galactosidase on the modified AgNPs. The optimal pH for soluble and carboxylated AgNPs adsorbed β-galactosidase (IβG) was observed at pH 4.5 while the optimal operating temperature was broadened from 50 ºC to 60 ºC for IβG. Michaelis constant, Km was increased two and a half fold for IβG while Vmax decreases slightly as compared to soluble enzyme. β-galactosidase immobilized on surface functionalized AgNPs retained 70% biocatalytic activity even at 4% galactose concentration as compared to enzyme in solution. Our study showed that IβG produces greater amount of galacto-oligosaccharides at higher temperatures (50 ºC and 60 ºC) from 0.1 mol L-1 lactose solution at pH 4.5 as compared to previous reports.

Lyssnande : en vårdvetenskaplig betraktelse

Denna vårdvetenskapliga studie har sökarljuset riktat mot lyssnande som något fundamentalt för människan. Studiens syfte är att utifrån forskarens traditionstillhörighet och en klart uttalad teorikärna, värdegrund, ontologisk grund samt en hermeneutisk ansats avtäcka nytt inseende om vad lyssnande är samt vad som är vårdande i lyssnande. Studiens avsikt är att bringa ontologisk klarhet, klargöra lyssnandets plats inom vårdvetenskaplig teoribildning samt bidra med bilder av det vårdande med relevans för klinisk praxis. Det hermeneutiska arbetssättet är en ständig rörelse mellan det enskilda och gemensamma. Den vårdvetenskapliga traditionens grundläggande ordning utgör siktet för kunskapssökandet samtidigt som det är gentemot den caritativa vårdteorin som nytt inseende ur historiska källor reflekteras för att lysa upp och synliggöra det evidenta och ursprungliga om lyssnande. Begreppsutredningen av lyssna som begrepp ger förståelse för begreppets historiska ursprung och dess starka band med begreppen lyss, lystra, lyda, följa, iaktta, se samt lust, begär, böjelse och glädje. Läsning och begrundan av filosoferna Bubers, Lévinas och författaren Dostojevskijs livsverk avtäcker vittnesbörd och stillbilder som tolkas för att synliggöra tolkningsantaganden om lyssnandets väsen och gestaltning. Jag har läst och begrundat texterna med öppenhet, lyhördhet och en kvardröjande hållning för att låta dem beröra, tilltala mig och framträda som något nytt. Ur de enskilda texterna avtäcks mönster av en gemensam inre ordning och en gemensam stillbild och tolkningsantaganden om lyssnande formas. När den gemensamma inre ordningen får sammanstråla med studiens vårdvetenskapliga grund synliggörs en urbild och teser om lyssnande samt det vårdande i lyssnande. Avtäckandet visar att lyssnande är en grundhållning till livet självt. Människan lyssnar till sitt innersta väsen för att tillägna sig en inre grundordning samt hörsamma sin tillhörighet i en mera allomfattande gemenskap till den skapande, den andre och det oändliga. I ljuset av kärlekens kraft och bejakandet av mänskligt lidande kan ensamhet och gemenskap sluta förbund med varandra i en mellanverklighet som bär oändlighetens och evighetens kännetecken, och som får toner av det heliga och eviga att ljuda i allt och alla i en närvaro här och nu. Lyssnande är en väsenshandling som uttalas genom en vårdande hållning att tjäna, offra och bära ansvar för den andre med medmänsklig barmhärtighet och medmänskligt medlidande. Band till den andre knyts genom den egna sårbarheten och genom att med ödmjukhet, äkthet och gästfrihet bjuda in och välkomna den andre i sin annanhet. Den vårdande gemenskapen skapar en rörelse som bär på en livsbringande kraft genom vilken människan uppnår frihet att varda, finna näring och försoning.

Ferromagnetic properties of pyrolytic nanocarbon

The work reported in this thesis is dedicated to irreversible magnetic properties in pyrolytic nanocarbon samples. Based on atomic force microscope images, the samples consist of carbon clusters with radius 30..120 nm. These are treated as single-domain nanoparticles. Magnetic hysteresis, field cooled, zero field cooled and thermoremanent magnetization measurements were performed using an RF SQUID magnetometer and ferromagnetic behaviour was observed. Analysis suggests that the ferromagnetic ordering is associated with defects in a thin surface layer, whose thickness is independent of particle size. Critical radius for single-domain particles, critical radius for coherent rotation, magnetic layer thickness, distance between elementary magnetic moments, saturation magnetization, exchange stiffness constant and anisotropy energy density are also presented.