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| 2. |
- Avizzano, C.A., et al.
(författare)
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Motor Learning Skill Experiments Using Haptic Interface Capabilities
- 2002
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Ingår i: 11th IEEE International Workshop on Robot and Human Interactive Communication. Proceedings.. - : IEEE. - 0780375459 ; , s. 198-203
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Konferensbidrag (refereegranskat)abstract
- This paper investigated the influence that proportional feedback programmed into haptic interface (HI) can have in the development of motor skills. The haptic interface design, adapted to the task to be performed, plays a key role inside motor learning processes as the kinesthetic and proprioceptive are the information pathway in the perception of incoming stimuli. Subjects learned to draw a shape using two kinds of training methods: visual, visual and haptic. The error position distance was measured and a statistical analysis was done in order to identify user's motion improvement when training trials were alternated with practice trials. In order to constraint the user to draw a predefined path, a control law is presented.
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| 4. |
- Saraiva, Jorge M., et al.
(författare)
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Issues in Human GenEthics
- 2001
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Ingår i: Genetics in Medicine. - 1098-3600. ; 3:3, s. 218-218
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Tidskriftsartikel (refereegranskat)
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| 5. |
- Chida, K., et al.
(författare)
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Development of the new anthropomorphic flutist robot WF-4
- 2004
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Ingår i: ICRA '04. 2004 IEEE International Conference on Robotics and Automation, 2004. Proceedings.. - 0780382323 ; , s. 152-157
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Konferensbidrag (refereegranskat)abstract
- Since 1990, we have been developing anthropomorphic flutist robots, which are mechanically similar to human organs needed for playing the flute. The goal of this research is to clarify the flute playing mechanism from an engineering point of view and to enable the communication with humans at emotional level. The control of the air beam parameters for obtaining a good sound is very important. Such parameters are related mainly to the lips shape and its relative position respect to the flute embouchure hole. Then, the newest version of the anthropomorphic flutist robot WF-4 has been implemented by improving the design of each part of the robot (lips, lungs, neck, etc.). This new version has succeeded in the improvement of the flute sound quality and the sound conversion efficiency. We describe the mechanical features of the WF-4 and the experiments done for evaluating its musical performance
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| 7. |
- Lipfert, Jan, et al.
(författare)
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Radiation Induced Damage in Serine Phosphate : Insights into a Mechanism for Direct DNA Strand Breakage
- 2004
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Ingår i: Journal of Physical Chemistry B. - : American Chemical Society (ACS). - 1520-6106 .- 1520-5207. ; 108:23, s. 8036-8042
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Tidskriftsartikel (refereegranskat)abstract
- The radiation-induced decomposition mechanisms of l-O-serine phosphate and the properties of the resulting radicals are explored at the hybrid Hartree−Fock−density functional theory level B3LYP, incorporating a polarized continuum model (IEF-PCM). Three different radical products were identified in earlier experimental studies, formed through deamination (radical I), decarboxylation plus radical exchange (radical II), or dephosphorylation (radical III) reactions, respectively. The calculated hyperfine coupling constants of the resulting radicals agree well with experimental data. The computed energetics for the two competing mechanisms resulting from electron capture, radicals I and III, show that the deamination reaction is barrierless, whereas the dephosphorylation reaction requires an initial electronic redistribution and formation of a phosphoranyl radical with trigonal bipyramidal geometry. From this, the dephosphorylation reaction has to overcome a barrier of approximately 26 kcal/mol, which explains the predominance of radical I over radical III in the experimental measurements. For radical II, the initial decarboxylation step resulting from electron loss was explored and found to proceed without barriers. The results of the current study have implications for radiation-induced damage of amino acids. In addition, serine phosphate is a model of a DNA sugar−phosphate fragment, and thus we may obtain new insights into a possible mechanism for cleavage of the phosphate ester bond of the DNA backbone leading to strand break.
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| 8. |
- Llano, Jorge, et al.
(författare)
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First Principles Electrochemical Study of Redox Events in DNA Bases and Chemical Repair in Aqueous Solution
- 2004
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Ingår i: Physical Chemistry, Chemical Physics - PCCP. - 1463-9076 .- 1463-9084. ; 6, s. 2426-2433
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Tidskriftsartikel (refereegranskat)abstract
- Primary and secondary radiation-induced damage to DNA, and chemical repair of the lesions on the nucleobases in solution involve a cascade of proton transfer (PT), electron transfer (ET), and proton-coupled electron transfer (PT-ET) reactions. The rate constants of these reactions depend on the standard Gibbs energy changes that can be derived from experiment. We here apply a first principles approach to calculate standard Gibbs energy changes of proton, electron, and proton-coupled electron transfer reactions in solution, wherein electrons and protons participate as independent ions; data that is fully compatible with that experimentally derived. Hence, the thermodynamic feasibility of ET and PT-ET pathways for these reactions depending on the effective concentration of hydrogen ions can be directly rationalized from first principles. The focus of this study is the primary and secondary ionization events in nucleobases in the presence of hydrogen atoms, solvated electrons and protons in aqueous solution, leading to the formation of nucleobase radical anions B˙−, radical cations B˙+ and their major deprotonated radical forms B(–H)˙. We also examine the chemical repair reaction by thiols, B(–H)˙(aq)+RSH(aq)=B(aq)+RS˙(aq), where B=A,G,C,T. Our results for the chemical repair of B(–H)˙ suggest that a PT-ET pathway should be favored for A and C at any pH, whereas for G and T, a PT-ET pathway is preferred at acidic and near neutral pH, but in the pH range 9-11, the ET pathway would dominate.
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| 9. |
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| 10. |
- Llano, Jorge, 1968-
(författare)
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Modern Computational Physical Chemistry : An Introduction to Biomolecular Radiation Damage and Phototoxicity
- 2004
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The realm of molecular physical chemistry ranges from the structure of matter and the fundamental atomic and molecular interactions to the macroscopic properties and processes arising from the average microscopic behaviour.Herein, the conventional electrodic problem is recast into the simpler molecular problem of finding the electrochemical, real chemical, and chemical potentials of the species involved in redox half-reactions. This molecular approach is followed to define the three types of absolute chemical potentials of species in solution and to estimate their standard values. This is achieved by applying the scaling laws of statistical mechanics to the collective behaviour of atoms and molecules, whose motion, interactions, and properties are described by first principles quantum chemistry. For atomic and molecular species, calculation of these quantities is within the computational implementations of wave function, density functional, and self-consistent reaction field theories. Since electrons and nuclei are the elementary particles in the realm of chemistry, an internally consistent set of absolute standard values within chemical accuracy is supplied for all three chemical potentials of electrons and protons in aqueous solution. As a result, problems in referencing chemical data are circumvented, and a uniform thermochemical treatment of electron, proton, and proton-coupled electron transfer reactions in solution is enabled.The formalism is applied to the primary and secondary radiation damage to DNA bases, e.g., absorption of UV light to yield electronically excited states, formation of radical ions, and transformation of nucleobases into mutagenic lesions as OH radical adducts and 8-oxoguanine. Based on serine phosphate as a model compound, some insight into the direct DNA strand break mechanism is given.Psoralens, also called furocoumarins, are a family of sensitizers exhibiting cytostatic and photodynamic actions, and hence, they are used in photochemotherapy. Molecular design of more efficient photosensitizers can contribute to enhance the photophysical and photochemical properties of psoralens and to reduce the phototoxic reactions. The mechanisms of photosensitization of furocoumarins connected to their dark toxicity are examined quantum chemically.
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