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J Ahopelto

Publications and source records attributed to J Ahopelto.

5 recordsLinked to original sources
PubMed2005

Intervalley-scattering-induced electron-phonon energy relaxation in many-valley semiconductors at low temperatures.

We report on the effect of elastic intervalley scattering on the energy transport between electrons and phonons in many-valley semiconductors. We derive a general expression for the electron-phonon energy flow rate at the limit where elastic intervalley scattering dominates over diffusion. Electron heating experiments on doped n-type Si samples with electron concentrations (3.5-16.0) x 10(25) m(-3) are performed at sub-Kelvin temperatures. We find a good agreement between the theory and the experiment.

Journal Article↗
PubMed1975

Detection of fetal QRS-complexes by external methods.

A new method is presented for detection of the QRS complexes and the fetal heart rate from the fetal magnetocardiogram and from the fetal electrocardiogram. In the method, the amplitude, the polarity and the shape of the QRS complex are tested. By using the described equipment it is possible to detect all consecutive heart beat intervals from a fetal electrocardiogram with less than 1% error in timing. When an external fetal electrocardiogram was used for testing, generally slightly over 10% of the QRS complexes were lost since they were simultaneous with the maternal complexes. In addition, complexes were also lost due to noise.

Electrocardiography↗