The mechanical behavior of the reed is an essential part of the sound production in single reed i... more The mechanical behavior of the reed is an essential part of the sound production in single reed instruments such as the saxophone and the clarinet. To investigate effect of mouthpiece design, reed materials and reed shapes, it is important to understand reed dynamics. In this paper, stroboscopic digital image correlation (DIC) is used to measure displacement and strain distribution of the reed surface as function of time while the reed is vibrating. Measurements are performed on synthetic and natural cane reeds in dry and wet condition. Data are recorded on 30 phase steps within the vibration period. Results show that DIC allows to obtain reliable quantitative results of strain values in both the direction along the reed fiber length as well as perpendicular to the fibers. On the synthetic and the dry cane reed maximal x-strain values, averaged over the visible part of the reed tip, are respectively 0.06% and 0.08%. Maximal y-strain values are respectively 0.07% and 0.09%. On the wet cane reed, x-strain amplitude is smaller (0.06%), but during the measurement time both x-strain and y-strain change strongly because of dehydration artifacts. Over a period of a few minutes, displacements and strains of the wet reed change strongly.
Accurate knowledge of the acquisition geometry of a CT scanning system is key for high quality to... more Accurate knowledge of the acquisition geometry of a CT scanning system is key for high quality tomographic imaging. Unfortunately, in modular X-ray CT setups, geometry misalignment occurs each time the setup is changed, which calls for an efficient calibration procedure to correct for geometric inaccuracies. Although many studies have been dealing with the calibration of X-ray CT systems, these are often specifically designed for one setup and/or expensive. In this work, we explore the possibilities of a low-cost, easy-tobuild, and modular phantom, constructed from LEGO bricks, which serves as a structure to hold small metal beads, for geometric calibration of a tomographic X-ray system. By estimating the bead coordinates using deep learning, and minimizing center-to-center distances of the metal beads between measured and reference projection data, geometry parameters are derived. With simulated as well as real experiments, it is shown that the LEGO phantom can be used to accurately estimate the geometry of a modular X-ray CT system.
Proceedings, annual meeting, Electron Microscopy Society of America, 1983
As part of a series of studies of the properties of human glioma cells that contribute to their a... more As part of a series of studies of the properties of human glioma cells that contribute to their ability to escape cell-mediated immune attack (Gately et al.,(1982)we have examined the ultrastructural features of a protective mucopolysaccharide coat secreted by some of these brain tumor cell lines. This ruthenium red-positive coat or "halo" is formed or greatly increases in size in response to the presence of lymphocytes or a soluble factor released therefrom. It blocks the approach of cytotoxic lymphocytes to the tumor cells and hence tumor cell killing. Hyaluronidase appears to be a major structural component. The "halo" is destroyed by bovine testicular or streptomyces hyaluronidase, and chondritinase ABC.To determine the ultrastructural features of this halo we have examined 5 human glioma cell lines in vitro. These were derived from I Grade II and 4 Grade IV astrocytomas, specimens of which were removed at surgery. Glioma derived (1000 per Costar well) were p...
The eardrum is the primary component of the middle ear and has been extensively investigated in h... more The eardrum is the primary component of the middle ear and has been extensively investigated in humans. Measuring the displacement and deformation of the eardrum under different quasi-static loading conditions gives insight in its mechanical behavior and is fundamental in determining the material properties of the eardrum. Currently, little is known about the behavior and material properties of eardrums in non-mammals. To explore the mechanical properties of the eardrum in non-mammalian ears, we investigated the quasi-static response of the eardrum of a common lizard: the Tokay gecko (Gekko gecko). The middle ear cavity was pressurized using repetitive linear pressure cycles ranging from-1.5 to 1.5 kPa with pressure change rates of 0.05, 0.1 and 0.2 kPa/s. The resulting shape, displacement and in-plane strain of the eardrum surface were measured using 3D digital image correlation. When middle-ear pressure is negative, the medial displacement of the eardrum is much larger than the displacement observed in mammals; when middle-ear pressure is positive, the lateral displacement is much larger than in mammals, which is not observed in bird single-ossicle ears. Peak-to-peak displacements are about 2.8 mm, which is larger than in any other species measured up to date. The peak-to-peak displacements are at least five times larger than observed in mammals. The pressure-displacement curves show hysteresis, and the energy loss within one pressure cycle increases with increasing pressure rate, contrary to what is observed in rabbit eardrums. The energy lost during a pressure cycle is not constant over the eardrum. Most energy is lost at the region where the eardrum connects to the hearing ossicle. Around this eardrum-ossicle region, a 5% increase in energy loss was observed when pressure change rate was increased from 0.05 kPa/s to 0.2 kPa/s. Other parts of the eardrum showed little increase in the energy loss. The orientation of the in-plane strain on the eardrum was mainly circumferential with strain amplitudes of about +1.5%. The periphery of the measured eardrum surface showed compression instead of stretching and had a different strain orientation. The TM of Gekko gecko shows the highest displacements of all species measured up till now. Our data show the first shape, displacement and deformation measurements on the surface of the eardrum of the gecko and indicate that there could exist a different hysteresis behavior in different species.
High sound pressure levels (> 120 dB) cause damage or death of the hair cells of the inner ear, h... more High sound pressure levels (> 120 dB) cause damage or death of the hair cells of the inner ear, hence causing hearing loss. Vocalization differences are present between hens and roosters. Crowing in roosters is reported to produce sound pressure levels of 100 dB measured at a distance of 1m. In this study we measured the sound pressure levels that exist at the entrance of the outer ear canal. We hypothesize that roosters may benefit from a passive protective mechanism while hens do not require such a mechanism. Audio recordings at the level of the entrance of the outer ear canal of crowing roosters, made in this study, indeed show that a protective mechanism is needed as sound pressure levels can reach amplitudes of 142.3 dB. Audio recordings made at varying distances from the crowing rooster show that at a distance of 0.5m sound pressure levels already drop to 102 dB. Micro-CT scans of a rooster and chicken head show that in roosters the auditory canal closes when the beak is opened. In hens the diameter of the auditory canal only narrows but does not close completely. A morphological difference between the sexes in shape of a bursa-like slit which occurs in the outer ear canal causes the outer ear canal to close in roosters but not in hens.
Because the quadrate and the eardrum are connected, the hypothesis was tested that birds attenuat... more Because the quadrate and the eardrum are connected, the hypothesis was tested that birds attenuate the transmission of sound through their ears by opening the bill, which potentially serves as an additional protective mechanism for self-generated vocalizations. In domestic chickens, it was examined if a difference exists between hens and roosters, given the difference in vocalization capacity between the sexes. To test the hypothesis, vibrations of the columellar footplate were measuredex vivowith laser Doppler vibrometry (LDV) for closed and maximally opened beak conditions, with sounds introduced at the ear canal. The average attenuation was 3.5 dB in roosters and only 0.5 dB in hens. To demonstrate the importance of a putative protective mechanism, audio recordings were performed of a crowing rooster. Sound pressures levels of 133.5 dB were recorded near the ears. The frequency content of the vocalizations was in accordance with the range of highest hearing sensitivity in chicken...
The aim of this work, was to compare pulse wave velocity (PWV) measurements using Laser Doppler v... more The aim of this work, was to compare pulse wave velocity (PWV) measurements using Laser Doppler vibrometry (LDV) and the more established ultrasound-based pulse wave imaging (PWI) in smooth vessels. Additionally, it was tested whether changes in phantom structure can be detected using LDV in vessels containing a local hardening of the vessel wall. Results from both methods showed good agreement illustrated by the non-parametric Spearman correlation analysis (Spearman-= 1 and p < 0.05) and the Bland-Altman analysis (mean bias of − 0.63 m/s and limits of agreement between − 0.35 and − 0.90 m/s). The PWV in soft phantoms as measured with LDV was 1.30 ± 0.40 m/s and the PWV in stiff phantoms was 3.6 ± 1.4 m/s. The PWV values in phantoms with inclusions were in between those of soft and stiff phantoms. However, using LDV, given the low number of measurement beams, the exact locations of inclusions could not be determined, and the PWV in the inclusions could not be measured. In conclusion, this study indicates that the PWV as measured with PWI is in good agreement with the PWV measured with LDV although the latter technique has lower spatial resolution, fewer markers and larger distances between beams. In further studies, more LDV beams will be used to allow detection of local changes in arterial wall dynamics due to e.g. small inclusions or local hardenings of the vessel wall.
Sixth International Conference on Vibration Measurements by Laser Techniques: Advances and Applications, 2004
The thickness of the tympanic membrane has to be known for the formulation of mathematical ear mo... more The thickness of the tympanic membrane has to be known for the formulation of mathematical ear models. Using a commercial confocal laser scanning microscope we have found that the tympanic membrane has parts thinner than 10 micron. In this study we were forced to excise the tympanic membranes and due the restricted working distance of the microscope objective, we had to flatten the tympanic membrane onto a glass plate. Although we were able to measure thickness in fresh samples, thickness could still have been altered by the preparation procedure. S. Khanna developed over the years a powerful heterodyne interferometer with confocal pinholes in the illumination and observation arms. Thanks to its sectioning capabilities it can measure vibrations of structures embedded within other tissue without the need to expose the structure. While using this equipment in measuring vibrations in the middle ear, the idea grew that the interferometer could also be used to measure thickness, by tracking the carrier level of the interferometer while the laser focus is driven through the membrane. The method looks full of promises as measurements on animals with the tympanic membrane still in its original niche are possible without a prior preparation of the membrane.
Pasangan suami isteri akan menempuh segala cara untuk mendapatkan keturunan, karena keturunan ada... more Pasangan suami isteri akan menempuh segala cara untuk mendapatkan keturunan, karena keturunan adalah anugerah yang dititipkan tuhan kepadanya. Bila pasangan suami isteri sudah berusaha tetapi keturunan belum mereka peroleh atau disebut infertilitas, maka usaha untuk memperoleh keturunan akan dilakukan mulai dari teknik sederhana sampai yang menggunakan teknologi yang canggih serta modern, namun tetap saja angka keberhasilan nya masih rendah. Dewasa ini telah diciptakan suatu metode untuk membantu para pasutri mendapatkan keturunan, yaitu dengan cara Assisted Reproductive Technology (ART), atau artinya dalam bahasa Indonesia Teknologi Reproduksi Berbantu. Salah satu metode ART adalah in vitro fertilization (IVF), atau yang dikenal dikalangan dokter maupun orang awam adalah Bayi Tabung. Dari semua cara penanganan infertilitas, maka ART banyak menimbulkan masalah etik, hukum dan sosial.
Aim: For decades, monophasic square wave pulses have been used for intravesical electrical stimul... more Aim: For decades, monophasic square wave pulses have been used for intravesical electrical stimulation (IVES) in diagnosis and treatment of lower urinary tract dysfunction. The use of other waveforms, more preferred by patients or more effective for neural stimulation, has hardly been studied before. This study compares the effect of several waveforms and derived parameters in IVES. Methods: IVES, performed in eight female Sprague-Dawley rats, was given for 300 sec with constant frequency (10 Hz) and current amplitude (6 mA) with unipolar square, biphasic square, asymmetric biphasic square, double square, unipolar exponential rise, biphasic exponential rise, and doubleexponential rise wavepulses with different pulse durations (2 Â 5 msec, 20 msec, or 2 Â 20 msec). Bladder pressure was recorded. Average current and average power were calculated. Results: Stimulations with the different waveforms resulted in the same maximal pressure rise (all P > 0.1). The average charge was zero for biphasic waveforms. For exponential rise pulse waveforms the total injected charge was lower than that for the monophasic square pulse waveform. The average power was the highest for biphasic waveforms and the lowest for monophasic double-exponential rise pulses waveform. Conclusions: Charge-balanced waveforms, which are more preferred by patients, are equally effective in evoking IVES-induced detrusor contraction as monophasic square pulse waveforms. Thus, it can be beneficial in clinical practice to replace the monophasic square pulse waveform for IVES by chargebalanced waveforms. Furthermore, the stimulation power and thus the requested energy can be reduced by changing the waveform. This can be important for electrical stimulation using implanted batteries. Neurourol. Urodynam. 30:169-173, 2011.
Tony Abi-Salloum Bernhard Adams Mehdi Alavinejad Victor V. Apollonov Mete Atature Bradley Atcheso... more Tony Abi-Salloum Bernhard Adams Mehdi Alavinejad Victor V. Apollonov Mete Atature Bradley Atcheson David Atchison Nicolas Avdelidis Sergey Babin Hans Bachor Burm Baek Daniel Balageas* Salvador Bará Marco Barbieri Cesare Barbieri Yury Barmenkov Liam Barry Michael Bass Yahya Baykal* Wilhelm Becker Gregorius C.G. Berkhout Shrikant Bharadwaj Raymond Bishop Paolo Bison Allan Boardman Maria Bondani John Botsis Lindsay Botten Alex Bowers Christian Brackmann Arthur Bradley Howard Brandt J. Bravo-Abad P. Brevet Giorgio Brida Neil Broderick Gerald Buller* John Bullough Stephen Burns Yangjian Cai* Qing Yu Cai Juan Campos Stefan Carp* Stefania Castelletto Andrey Chabanov Prem Chahal Uday Chakraborty Benoit Champagne Neil Charman Y.F. Chauvet Pierre Chavel Sabino Chavez Cerda Nanguang Chen Zhigang Chen Yihang Chen C. Chen K. Chen Weibin Chen Xi Chen Vladimir Chernyak Jessica Cheung Frederic Chevy Demetrios Christodoulides Christopher Chunnilall* Bernard Claudet C. Clavero Leon Cohen Dan Cojoc Roger Colbeck Hendrik Coldenstrodt-Ronge Carlo Corsi Stelios Couris Lorenzo Crocco Jiri Ctyroky Salvador Cuevas M. da Luz Jerry Dadap Jean Daillant Iyad Dajani G. Dattoli Eric Dauler Jon Davis* F. De Leornadis Gilbert De Mey Diego de Ortueta Ivo Degiovanni Fu-Guo Deng Mark Dennis* Yujie Ding José Dintinger Joris Dirckx C.R. Doerr Adrian Doicu John Donohue S. Dubey John Dudley Christopher Dunsby Jan Dutkiewicz Geoffrey Duxbury Chris Edwards H.J. Eichler F. Eilenberger* Jens Eisert Hichem Eleuch Andrew Ellis R. Eplee Daniel Erni Harmut Erzgraber Joerg Evers* Halil Eyyuboglu Claude Fabre Yi-Chin Fang Zoltán Fazekas A. Felipe
In experimental studies it was found that otitis media causes stiVness loss in the tympanic membr... more In experimental studies it was found that otitis media causes stiVness loss in the tympanic membrane, possible precursors to retraction pockets and cholesteatoma. Besides otitis media habitual sniYng behaviour is associated with the development of retractions. The present study aims to test the hypothesis that repeated sniYng manoeuvre may cause not only structural, epithelial tympanic membrane changes presumed to be possible precursors to retractions, but also tympanic membrane stiVness loss, another possible mediator for the development of retractions. An experimental model with a pressure chamber was used to mimic the pressure conditions for the tympanic membrane in habitual sniVers' ears. The stiVness properties of twelve Mongolian gerbil tympanic membranes were measured with moiré interferometry after varying time up to 12 days with repeated pressure loading. Three days later, lower overall displacement were obtained in two ears; after 7-12 days the displacement readings were normal. This study with maximum of 12 days of pressure loading did not verify the hypothesis that habitual "sniYng" impairs the stiVness of the tympanic membrane.
In an interferometer which uses a reference surface, the measured surface heights correspond to t... more In an interferometer which uses a reference surface, the measured surface heights correspond to the difference between the test and reference surfaces. To accurately determine the rms roughness of supersmooth surfaces, the effects of the reference surface roughness need to be removed. One technique for doing this involves averaging a number of uncorrelated measurements of a mirror to generate a reference surface profile which can then be subtracted from subsequent measurements so that they do not contain errors due to the reference surface. The other technique provides an accurate rms roughness of the surface by taking two uncorrelated measurements of the surface. These two techniques for measurement of supersmooth surfaces are described in detail, and results of the measurement of a 0.7-A rms roughness mirror are presented. The expected error in the rms roughness measurement of a supersmooth mirror due to instrument noise is 0.02 A.
Ossicular fixation through otosclerosis, chronic otitis media and other pathologies, especially t... more Ossicular fixation through otosclerosis, chronic otitis media and other pathologies, especially tympanosclerosis, are treated by surgery if hearing aids fail as an alternative. However, the best hearing outcome is often based on knowledge of the degree and location of the fixation. Objective methods to quantify the degree and position of the fixation are largely lacking. Laser vibrometry is a known method to detect ossicular fixation but clinical applicability remains limited. A new method, minimally invasive laser vibrometry (MIVIB), is presented to quantify ossicle mobility using laser vibrometry measurement through the ear canal after elevating the tympanic membrane, thus making the method feasible in minimally invasive explorative surgery. A floating mass transducer provides a clinically relevant transducer to drive ossicular vibration. This device was attached to the manubrium and drove vibrations at the same angle as the longitudinal axis of the stapes and was therefore used t...
Recently, synchrotron radiation computed microtomography (SRµCT) has emerged as a promising tool ... more Recently, synchrotron radiation computed microtomography (SRµCT) has emerged as a promising tool for non-destructive, in situ visualization of cochlear implant electrode arrays inserted into a human cochlea. Histological techniques have been the `gold standard' technique for accurate localization of cochlear implant electrodes but are suboptimal for precise three-dimensional measurements. Here, an SRµCT experimental setup is proposed that offers the benefit of a high spatial and contrast resolution (isotropic voxel size = 4.95 µm and propagation-based phase-contrast imaging), while visualizing the soft-tissue structures and electrode array of the cochlear implant simultaneously. In this work, perimodiolar electrode arrays have been tested, which incorporate thick and closely spaced platinum–iridium contacts and wiring. These data can assist cochlear implant and hearing research, can be used to verify electrode segmentation techniques for clinical computed tomography or could be ...
The mechanical behavior of the reed is an essential part of the sound production in single reed i... more The mechanical behavior of the reed is an essential part of the sound production in single reed instruments such as the saxophone and the clarinet. To investigate effect of mouthpiece design, reed materials and reed shapes, it is important to understand reed dynamics. In this paper, stroboscopic digital image correlation (DIC) is used to measure displacement and strain distribution of the reed surface as function of time while the reed is vibrating. Measurements are performed on synthetic and natural cane reeds in dry and wet condition. Data are recorded on 30 phase steps within the vibration period. Results show that DIC allows to obtain reliable quantitative results of strain values in both the direction along the reed fiber length as well as perpendicular to the fibers. On the synthetic and the dry cane reed maximal x-strain values, averaged over the visible part of the reed tip, are respectively 0.06% and 0.08%. Maximal y-strain values are respectively 0.07% and 0.09%. On the wet cane reed, x-strain amplitude is smaller (0.06%), but during the measurement time both x-strain and y-strain change strongly because of dehydration artifacts. Over a period of a few minutes, displacements and strains of the wet reed change strongly.
Accurate knowledge of the acquisition geometry of a CT scanning system is key for high quality to... more Accurate knowledge of the acquisition geometry of a CT scanning system is key for high quality tomographic imaging. Unfortunately, in modular X-ray CT setups, geometry misalignment occurs each time the setup is changed, which calls for an efficient calibration procedure to correct for geometric inaccuracies. Although many studies have been dealing with the calibration of X-ray CT systems, these are often specifically designed for one setup and/or expensive. In this work, we explore the possibilities of a low-cost, easy-tobuild, and modular phantom, constructed from LEGO bricks, which serves as a structure to hold small metal beads, for geometric calibration of a tomographic X-ray system. By estimating the bead coordinates using deep learning, and minimizing center-to-center distances of the metal beads between measured and reference projection data, geometry parameters are derived. With simulated as well as real experiments, it is shown that the LEGO phantom can be used to accurately estimate the geometry of a modular X-ray CT system.
Proceedings, annual meeting, Electron Microscopy Society of America, 1983
As part of a series of studies of the properties of human glioma cells that contribute to their a... more As part of a series of studies of the properties of human glioma cells that contribute to their ability to escape cell-mediated immune attack (Gately et al.,(1982)we have examined the ultrastructural features of a protective mucopolysaccharide coat secreted by some of these brain tumor cell lines. This ruthenium red-positive coat or "halo" is formed or greatly increases in size in response to the presence of lymphocytes or a soluble factor released therefrom. It blocks the approach of cytotoxic lymphocytes to the tumor cells and hence tumor cell killing. Hyaluronidase appears to be a major structural component. The "halo" is destroyed by bovine testicular or streptomyces hyaluronidase, and chondritinase ABC.To determine the ultrastructural features of this halo we have examined 5 human glioma cell lines in vitro. These were derived from I Grade II and 4 Grade IV astrocytomas, specimens of which were removed at surgery. Glioma derived (1000 per Costar well) were p...
The eardrum is the primary component of the middle ear and has been extensively investigated in h... more The eardrum is the primary component of the middle ear and has been extensively investigated in humans. Measuring the displacement and deformation of the eardrum under different quasi-static loading conditions gives insight in its mechanical behavior and is fundamental in determining the material properties of the eardrum. Currently, little is known about the behavior and material properties of eardrums in non-mammals. To explore the mechanical properties of the eardrum in non-mammalian ears, we investigated the quasi-static response of the eardrum of a common lizard: the Tokay gecko (Gekko gecko). The middle ear cavity was pressurized using repetitive linear pressure cycles ranging from-1.5 to 1.5 kPa with pressure change rates of 0.05, 0.1 and 0.2 kPa/s. The resulting shape, displacement and in-plane strain of the eardrum surface were measured using 3D digital image correlation. When middle-ear pressure is negative, the medial displacement of the eardrum is much larger than the displacement observed in mammals; when middle-ear pressure is positive, the lateral displacement is much larger than in mammals, which is not observed in bird single-ossicle ears. Peak-to-peak displacements are about 2.8 mm, which is larger than in any other species measured up to date. The peak-to-peak displacements are at least five times larger than observed in mammals. The pressure-displacement curves show hysteresis, and the energy loss within one pressure cycle increases with increasing pressure rate, contrary to what is observed in rabbit eardrums. The energy lost during a pressure cycle is not constant over the eardrum. Most energy is lost at the region where the eardrum connects to the hearing ossicle. Around this eardrum-ossicle region, a 5% increase in energy loss was observed when pressure change rate was increased from 0.05 kPa/s to 0.2 kPa/s. Other parts of the eardrum showed little increase in the energy loss. The orientation of the in-plane strain on the eardrum was mainly circumferential with strain amplitudes of about +1.5%. The periphery of the measured eardrum surface showed compression instead of stretching and had a different strain orientation. The TM of Gekko gecko shows the highest displacements of all species measured up till now. Our data show the first shape, displacement and deformation measurements on the surface of the eardrum of the gecko and indicate that there could exist a different hysteresis behavior in different species.
High sound pressure levels (> 120 dB) cause damage or death of the hair cells of the inner ear, h... more High sound pressure levels (> 120 dB) cause damage or death of the hair cells of the inner ear, hence causing hearing loss. Vocalization differences are present between hens and roosters. Crowing in roosters is reported to produce sound pressure levels of 100 dB measured at a distance of 1m. In this study we measured the sound pressure levels that exist at the entrance of the outer ear canal. We hypothesize that roosters may benefit from a passive protective mechanism while hens do not require such a mechanism. Audio recordings at the level of the entrance of the outer ear canal of crowing roosters, made in this study, indeed show that a protective mechanism is needed as sound pressure levels can reach amplitudes of 142.3 dB. Audio recordings made at varying distances from the crowing rooster show that at a distance of 0.5m sound pressure levels already drop to 102 dB. Micro-CT scans of a rooster and chicken head show that in roosters the auditory canal closes when the beak is opened. In hens the diameter of the auditory canal only narrows but does not close completely. A morphological difference between the sexes in shape of a bursa-like slit which occurs in the outer ear canal causes the outer ear canal to close in roosters but not in hens.
Because the quadrate and the eardrum are connected, the hypothesis was tested that birds attenuat... more Because the quadrate and the eardrum are connected, the hypothesis was tested that birds attenuate the transmission of sound through their ears by opening the bill, which potentially serves as an additional protective mechanism for self-generated vocalizations. In domestic chickens, it was examined if a difference exists between hens and roosters, given the difference in vocalization capacity between the sexes. To test the hypothesis, vibrations of the columellar footplate were measuredex vivowith laser Doppler vibrometry (LDV) for closed and maximally opened beak conditions, with sounds introduced at the ear canal. The average attenuation was 3.5 dB in roosters and only 0.5 dB in hens. To demonstrate the importance of a putative protective mechanism, audio recordings were performed of a crowing rooster. Sound pressures levels of 133.5 dB were recorded near the ears. The frequency content of the vocalizations was in accordance with the range of highest hearing sensitivity in chicken...
The aim of this work, was to compare pulse wave velocity (PWV) measurements using Laser Doppler v... more The aim of this work, was to compare pulse wave velocity (PWV) measurements using Laser Doppler vibrometry (LDV) and the more established ultrasound-based pulse wave imaging (PWI) in smooth vessels. Additionally, it was tested whether changes in phantom structure can be detected using LDV in vessels containing a local hardening of the vessel wall. Results from both methods showed good agreement illustrated by the non-parametric Spearman correlation analysis (Spearman-= 1 and p < 0.05) and the Bland-Altman analysis (mean bias of − 0.63 m/s and limits of agreement between − 0.35 and − 0.90 m/s). The PWV in soft phantoms as measured with LDV was 1.30 ± 0.40 m/s and the PWV in stiff phantoms was 3.6 ± 1.4 m/s. The PWV values in phantoms with inclusions were in between those of soft and stiff phantoms. However, using LDV, given the low number of measurement beams, the exact locations of inclusions could not be determined, and the PWV in the inclusions could not be measured. In conclusion, this study indicates that the PWV as measured with PWI is in good agreement with the PWV measured with LDV although the latter technique has lower spatial resolution, fewer markers and larger distances between beams. In further studies, more LDV beams will be used to allow detection of local changes in arterial wall dynamics due to e.g. small inclusions or local hardenings of the vessel wall.
Sixth International Conference on Vibration Measurements by Laser Techniques: Advances and Applications, 2004
The thickness of the tympanic membrane has to be known for the formulation of mathematical ear mo... more The thickness of the tympanic membrane has to be known for the formulation of mathematical ear models. Using a commercial confocal laser scanning microscope we have found that the tympanic membrane has parts thinner than 10 micron. In this study we were forced to excise the tympanic membranes and due the restricted working distance of the microscope objective, we had to flatten the tympanic membrane onto a glass plate. Although we were able to measure thickness in fresh samples, thickness could still have been altered by the preparation procedure. S. Khanna developed over the years a powerful heterodyne interferometer with confocal pinholes in the illumination and observation arms. Thanks to its sectioning capabilities it can measure vibrations of structures embedded within other tissue without the need to expose the structure. While using this equipment in measuring vibrations in the middle ear, the idea grew that the interferometer could also be used to measure thickness, by tracking the carrier level of the interferometer while the laser focus is driven through the membrane. The method looks full of promises as measurements on animals with the tympanic membrane still in its original niche are possible without a prior preparation of the membrane.
Pasangan suami isteri akan menempuh segala cara untuk mendapatkan keturunan, karena keturunan ada... more Pasangan suami isteri akan menempuh segala cara untuk mendapatkan keturunan, karena keturunan adalah anugerah yang dititipkan tuhan kepadanya. Bila pasangan suami isteri sudah berusaha tetapi keturunan belum mereka peroleh atau disebut infertilitas, maka usaha untuk memperoleh keturunan akan dilakukan mulai dari teknik sederhana sampai yang menggunakan teknologi yang canggih serta modern, namun tetap saja angka keberhasilan nya masih rendah. Dewasa ini telah diciptakan suatu metode untuk membantu para pasutri mendapatkan keturunan, yaitu dengan cara Assisted Reproductive Technology (ART), atau artinya dalam bahasa Indonesia Teknologi Reproduksi Berbantu. Salah satu metode ART adalah in vitro fertilization (IVF), atau yang dikenal dikalangan dokter maupun orang awam adalah Bayi Tabung. Dari semua cara penanganan infertilitas, maka ART banyak menimbulkan masalah etik, hukum dan sosial.
Aim: For decades, monophasic square wave pulses have been used for intravesical electrical stimul... more Aim: For decades, monophasic square wave pulses have been used for intravesical electrical stimulation (IVES) in diagnosis and treatment of lower urinary tract dysfunction. The use of other waveforms, more preferred by patients or more effective for neural stimulation, has hardly been studied before. This study compares the effect of several waveforms and derived parameters in IVES. Methods: IVES, performed in eight female Sprague-Dawley rats, was given for 300 sec with constant frequency (10 Hz) and current amplitude (6 mA) with unipolar square, biphasic square, asymmetric biphasic square, double square, unipolar exponential rise, biphasic exponential rise, and doubleexponential rise wavepulses with different pulse durations (2 Â 5 msec, 20 msec, or 2 Â 20 msec). Bladder pressure was recorded. Average current and average power were calculated. Results: Stimulations with the different waveforms resulted in the same maximal pressure rise (all P > 0.1). The average charge was zero for biphasic waveforms. For exponential rise pulse waveforms the total injected charge was lower than that for the monophasic square pulse waveform. The average power was the highest for biphasic waveforms and the lowest for monophasic double-exponential rise pulses waveform. Conclusions: Charge-balanced waveforms, which are more preferred by patients, are equally effective in evoking IVES-induced detrusor contraction as monophasic square pulse waveforms. Thus, it can be beneficial in clinical practice to replace the monophasic square pulse waveform for IVES by chargebalanced waveforms. Furthermore, the stimulation power and thus the requested energy can be reduced by changing the waveform. This can be important for electrical stimulation using implanted batteries. Neurourol. Urodynam. 30:169-173, 2011.
Tony Abi-Salloum Bernhard Adams Mehdi Alavinejad Victor V. Apollonov Mete Atature Bradley Atcheso... more Tony Abi-Salloum Bernhard Adams Mehdi Alavinejad Victor V. Apollonov Mete Atature Bradley Atcheson David Atchison Nicolas Avdelidis Sergey Babin Hans Bachor Burm Baek Daniel Balageas* Salvador Bará Marco Barbieri Cesare Barbieri Yury Barmenkov Liam Barry Michael Bass Yahya Baykal* Wilhelm Becker Gregorius C.G. Berkhout Shrikant Bharadwaj Raymond Bishop Paolo Bison Allan Boardman Maria Bondani John Botsis Lindsay Botten Alex Bowers Christian Brackmann Arthur Bradley Howard Brandt J. Bravo-Abad P. Brevet Giorgio Brida Neil Broderick Gerald Buller* John Bullough Stephen Burns Yangjian Cai* Qing Yu Cai Juan Campos Stefan Carp* Stefania Castelletto Andrey Chabanov Prem Chahal Uday Chakraborty Benoit Champagne Neil Charman Y.F. Chauvet Pierre Chavel Sabino Chavez Cerda Nanguang Chen Zhigang Chen Yihang Chen C. Chen K. Chen Weibin Chen Xi Chen Vladimir Chernyak Jessica Cheung Frederic Chevy Demetrios Christodoulides Christopher Chunnilall* Bernard Claudet C. Clavero Leon Cohen Dan Cojoc Roger Colbeck Hendrik Coldenstrodt-Ronge Carlo Corsi Stelios Couris Lorenzo Crocco Jiri Ctyroky Salvador Cuevas M. da Luz Jerry Dadap Jean Daillant Iyad Dajani G. Dattoli Eric Dauler Jon Davis* F. De Leornadis Gilbert De Mey Diego de Ortueta Ivo Degiovanni Fu-Guo Deng Mark Dennis* Yujie Ding José Dintinger Joris Dirckx C.R. Doerr Adrian Doicu John Donohue S. Dubey John Dudley Christopher Dunsby Jan Dutkiewicz Geoffrey Duxbury Chris Edwards H.J. Eichler F. Eilenberger* Jens Eisert Hichem Eleuch Andrew Ellis R. Eplee Daniel Erni Harmut Erzgraber Joerg Evers* Halil Eyyuboglu Claude Fabre Yi-Chin Fang Zoltán Fazekas A. Felipe
In experimental studies it was found that otitis media causes stiVness loss in the tympanic membr... more In experimental studies it was found that otitis media causes stiVness loss in the tympanic membrane, possible precursors to retraction pockets and cholesteatoma. Besides otitis media habitual sniYng behaviour is associated with the development of retractions. The present study aims to test the hypothesis that repeated sniYng manoeuvre may cause not only structural, epithelial tympanic membrane changes presumed to be possible precursors to retractions, but also tympanic membrane stiVness loss, another possible mediator for the development of retractions. An experimental model with a pressure chamber was used to mimic the pressure conditions for the tympanic membrane in habitual sniVers' ears. The stiVness properties of twelve Mongolian gerbil tympanic membranes were measured with moiré interferometry after varying time up to 12 days with repeated pressure loading. Three days later, lower overall displacement were obtained in two ears; after 7-12 days the displacement readings were normal. This study with maximum of 12 days of pressure loading did not verify the hypothesis that habitual "sniYng" impairs the stiVness of the tympanic membrane.
In an interferometer which uses a reference surface, the measured surface heights correspond to t... more In an interferometer which uses a reference surface, the measured surface heights correspond to the difference between the test and reference surfaces. To accurately determine the rms roughness of supersmooth surfaces, the effects of the reference surface roughness need to be removed. One technique for doing this involves averaging a number of uncorrelated measurements of a mirror to generate a reference surface profile which can then be subtracted from subsequent measurements so that they do not contain errors due to the reference surface. The other technique provides an accurate rms roughness of the surface by taking two uncorrelated measurements of the surface. These two techniques for measurement of supersmooth surfaces are described in detail, and results of the measurement of a 0.7-A rms roughness mirror are presented. The expected error in the rms roughness measurement of a supersmooth mirror due to instrument noise is 0.02 A.
Ossicular fixation through otosclerosis, chronic otitis media and other pathologies, especially t... more Ossicular fixation through otosclerosis, chronic otitis media and other pathologies, especially tympanosclerosis, are treated by surgery if hearing aids fail as an alternative. However, the best hearing outcome is often based on knowledge of the degree and location of the fixation. Objective methods to quantify the degree and position of the fixation are largely lacking. Laser vibrometry is a known method to detect ossicular fixation but clinical applicability remains limited. A new method, minimally invasive laser vibrometry (MIVIB), is presented to quantify ossicle mobility using laser vibrometry measurement through the ear canal after elevating the tympanic membrane, thus making the method feasible in minimally invasive explorative surgery. A floating mass transducer provides a clinically relevant transducer to drive ossicular vibration. This device was attached to the manubrium and drove vibrations at the same angle as the longitudinal axis of the stapes and was therefore used t...
Recently, synchrotron radiation computed microtomography (SRµCT) has emerged as a promising tool ... more Recently, synchrotron radiation computed microtomography (SRµCT) has emerged as a promising tool for non-destructive, in situ visualization of cochlear implant electrode arrays inserted into a human cochlea. Histological techniques have been the `gold standard' technique for accurate localization of cochlear implant electrodes but are suboptimal for precise three-dimensional measurements. Here, an SRµCT experimental setup is proposed that offers the benefit of a high spatial and contrast resolution (isotropic voxel size = 4.95 µm and propagation-based phase-contrast imaging), while visualizing the soft-tissue structures and electrode array of the cochlear implant simultaneously. In this work, perimodiolar electrode arrays have been tested, which incorporate thick and closely spaced platinum–iridium contacts and wiring. These data can assist cochlear implant and hearing research, can be used to verify electrode segmentation techniques for clinical computed tomography or could be ...
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