Publications by authors named "Esko M Toppila"

4 Publications

  • Page 1 of 1

Wavelet analysis to detect gait events.

Annu Int Conf IEEE Eng Med Biol Soc 2009 ;2009:424-7

Finnish Institute of Occupational Health, FI-00250 Helsinki, Finland.

Manually detecting gait events by visual inspection of gait data is laborious. Currently, there are no robust techniques available to automate the process. However, detecting gait events is essentially a classification problem; an application for which wavelet analysis, a multiresolution technique, is well suited for. We employ wavelet analysis to classify heel strike- and toe off events using the ground reaction forces that are exerted during walking. We recorded the ground reaction forces for 30 unshod healthy subjects while they were stepping in place on a force platform for 30 s at a self-selected pace. Depending on the pace, each subject completed 14-26 gait cycles. We compared the timing of events detected with the wavelet analysis with the timing of events detected by analyzing the signal time-derivative. On average, the wavelet analysis detected the events 29 ms later. This difference corresponds to 1.2% of the average duration of the gait cycles, which was 2.4 s. Wavelet analysis shows promise for automated detection of gait events.
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http://dx.doi.org/10.1109/IEMBS.2009.5333137DOI Listing
April 2010

Mucosal eosinophils and l-selectin ligands are associated with invasive and noninvasive sinus surgery outcomes.

Am J Rhinol Allergy 2009 Jan-Feb;23(1):21-7

Department of Clinical Medicine University of Tampere, Tampere, Finland.

Background: Chronic rhinosinusitis (CRS) is characterized by persistent inflammation of the nasal and paranasal mucosa with numerous emigrated leukocytes. L-Selectin on leukocytes and its endothelial glycosylated ligands initiate leukocyte infiltration into inflamed tissues. Endoscopic sinus surgery (ESS) is the major approach for restoring sinus physiology after failure of conservative therapy; however, the effect of enlarging the maxillary sinus ostium is still unknown. Here, we compared two histological markers of local inflammation, the number of mucosal eosinophils, and the expression of endothelial L-selectin ligands, with clinical outcomes after enlarging or saving the maxillary sinus ostium.

Methods: Twenty-three patients with CRS underwent uncinectomy on one side and additional middle meatal antrostomy on the other side. Maxillary sinus mucosa biopsy specimens from these patients and nine healthy subjects were taken for immunohistochemical evaluations of the number of mucosal eosinophils and endothelial L-Selectin ligands. Also, symptoms and mucociliary clearance were measured.

Results: The postoperative reduction of the endothelial L-Selectin ligands was independent of the operation technique. There was a correlation between postoperative number of mucosal eosinophils and symptom score, which was also independent of the surgical technique. The postoperative decrease of mucosal eosinophils, as well as the correlation of the intraoperative eosinophils with the postoperative symptom score, was found only on antrostomy side.

Conclusion: ESS decreases the expression of endothelial L-Selectin ligands, which might lead to decreased eosinophil traffic into maxillary sinus mucosa, putatively more when enlarging the maxillary sinus ostium. Both intra- and postoperative low number of eosinophils seem to be indicators of good subjective recovery.
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http://dx.doi.org/10.2500/ajra.2009.23.3250DOI Listing
May 2009

Evaluating sleepiness using force platform posturography.

IEEE Trans Biomed Eng 2006 Aug;53(8):1578-85

Department of Physical Sciences, University of Helsinki.

We have investigated the feasibility to use posturography as a method to estimate sleep deprivation. This manuscript presents a proof-of-concept of this idea. Twenty-one healthy subjects aged 20-37 years participated in the study. The subjects were deprived of sleep for up to 36 h. Their postural stability was measured as a function of sleep deprivation time. As a reference the critical fusion frequency method for measuring sleepiness was used. The 163 posturographic parameters used for analyzing the posturographic data were found from the literature. Of these parameters, the fractal dimension of the sway path, the most common frequency of the sway, the time-interval for open-loop control of stance, and the most common amplitude of the sway showed the highest linear correlations with sleep deprivation time. Using these four parameters we were able to estimate the sleep deprivation time with an accuracy better than 5 h for 80% of the subjects.
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http://dx.doi.org/10.1109/TBME.2006.878069DOI Listing
August 2006

Sound exposure among the Finnish National Opera personnel.

Appl Occup Environ Hyg 2003 Mar;18(3):177-82

Department of Physics, Finnish Institute of Occupational Health, Helsinki, Finland.

The purpose of the study was to determine how and when the personnel of the Finnish National Opera are exposed to noise and whether exposure depends on musical selection of repertoire. Additionally, an evaluation of sound exposure level due to individual rehearsals was included. The measurements were done using individual noise dosimeters and fixed-point measurements. From the measurements, annual noise exposure in the Opera was evaluated. The conductors, dancers, and double bass players were exposed to levels below 85 decibels, A-weighted, dB(A), which is the national action level. The choir members were exposed to sound levels of 92 and 94 dB(A). Within the orchestra, the highest sound exposure levels were found among percussionists, 95 dB(A); flute/piccolo players, 95 dB(A); and brass players, 92-94 dB(A). Other sound exposure levels among orchestra members varied from 83 to 89 dB(A). Soloists and rehearsal pianists are likely to be exposed to sound levels exceeding the national action level. From an exposure perspective, the individual rehearsals, 79-100 dB(A), proved to be as important as performances and group rehearsals, 82-99 dB(A), among orchestra musicians and choir singers. The ambient sound level for the lighting crew was 76 +/- 4 dB(A). However, the measured sound levels at the ear varied from 77 to 92 dB(A) due to the communication via headphones that had individual volume control. For the majority of personnel of the Finnish National Opera, sound exposure level exceeded the national action level value of 85 dB(A). Artists exceeded the action level during both individual and group rehearsals, as well as during performances. Hearing protection has been designed for musicians. Education/reinforcement is required to ensure it is worn.
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http://dx.doi.org/10.1080/10473220301356DOI Listing
March 2003