Development, maturation and learning influence on handwriting kinematics.

Handwriting is the result of a process in which linguistic, psychomotor and biomechanical factors interact with physical maturation, cognitive development and learning. Digital tablets, which record the writing in real time, allow a kinematic analysis of written trace: the implemented algorithms analyze parameters as length, duration and speed of the components (trace between two pen-lifts) and strokes (trace between two minima of curvilinear velocity). The purpose of this work is to fill, at least for Italy, the lack of normative data on typical handwriting processes. This cross-sectional study will present data on 218 right-handed and Italian mother-tongue students, attending classes from 2nd to 8th grade. They performed specific tasks (tests of writing speed; transcription of a sentence accurately vs. speedily) by a digital tablet. The analysis showed many changes of the considered parameters across the classes, as in the horizontal, curvilinear mean and peak velocities of components and strokes, with higher values in the last years of schooling and a parallel decrease in the number of strokes/letter (improvement of automation). In conclusion, some of these parameters are useful for studying development and learning of writing and their values can be used as references to evaluate samples with different characteristics.

Reprint of 'Development, maturation and learning influence on handwriting kinematics'.

Handwriting is the result of a process in which linguistic, psychomotor and biomechanical factors interact with physical maturation, cognitive development and learning. Digital tablets, which record the writing in real time, allow a kinematic analysis of written trace: the implemented algorithms analyze parameters as length, duration and speed of the components (trace between two pen-lifts) and strokes (trace between two minima of curvilinear velocity). The purpose of this work is to fill, at least for Italy, the lack of normative data on typical handwriting processes. This cross-sectional study will present data on 218 right-handed and Italian mother-tongue students, attending classes from 2nd to 8th grade. They performed specific tasks (tests of writing speed; transcription of a sentence accurately vs. speedily) by a digital tablet. The analysis showed many changes of the considered parameters across the classes, as in the horizontal, curvilinear mean and peak velocities of components and strokes, with higher values in the last years of schooling and a parallel decrease in the number of strokes/letter (improvement of automation). In conclusion, some of these parameters are useful for studying development and learning of writing and their values can be used as references to evaluate samples with different characteristics.

Acute and chronic high-frequency properties of cardiac pacing and defibrillation leads.

The purpose of our study was to investigate variety of cardiac lead conductor designs as high-frequency (HF) transmission lines. Special attention was given on evaluation of chronic HF applications in cardiac electrotherapy. We measured the characteristic impedance and the attenuation coefficient of six pacing leads between 1 and 21 MHz. They were subsequently immersed into the saline solution simulating the body fluid and the measurements were repeated 10 years later. Identical measurements were performed on 15 new pacing and defibrillation leads. The results revealed that lead geometry is the main factor affecting the HF parameters. Attenuation coefficients of old and contemporary leads do not differ significantly. Penetration of saline within the leads during a decade did not influence much their HF characteristics. Thus, a chronic cardiac contraction sensor based on lead's HF impedance variation is feasible. The signal losses of ultrasonic transducers mounted on the lead might be stable for years at acceptable levels without significant variation. Due to mutually similar values of HF parameters in different leads, design of tensiometric or ultrasonic applications could be universal for majority of commercially available leads. Automatic system calibration could be developed for each and every lead after determination of its HF parameters.

Acute animal and human study of tensiometric pacing lead sensor based on triboelectricity.

Cardiac contractions bend the implanted cardiac lead body, extend and compress the lead conductors, their insulation and the inserted stylet. Magnitude of lead deflection depends on cardiac muscle contraction forces. The purpose of study was to measure the charge generated due to triboelectric effect between one of the lead conductors and the inserted stylet. The charge was measured by differential charge amplifier being connected to isolation amplifier and power supply. Sensor signal, ECG and intracardiac electrograms were acquired. Three models of custom designed leads were implanted in 8 sheep. Measurements were done in 18 patients undergoing pacemaker implantation and replacement procedures. Atrial and ventricular tensiometric signals were recorded in dual chamber and in single-lead VDD patients. Recordings in sinus rhythm at various AV intervals and in supraventricular tachycardia were done. In average, charge variation between 1 and 600 pC was measured. Tensiometric stylet could be feasible hemodynamic sensor for myocardial contraction detection. Its main advantage is that it is easily exchangeable and universal for all leads.