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  • 51.
    Jalkanen, Ville
    et al.
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskaplig fakultet, Centrum för medicinsk teknik och fysik.
    Andersson, Britt M
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskaplig fakultet, Centrum för medicinsk teknik och fysik.
    Bergh, Anders
    Umeå universitet, Medicinsk fakultet, Medicinsk biovetenskap.
    Ljungberg, Börje
    Umeå universitet, Medicinsk fakultet, Kirurgisk och perioperativ vetenskap.
    Lindahl, Olof A
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskaplig fakultet, Centrum för medicinsk teknik och fysik.
    Prostate tissue stiffness as measured with a resonance sensor system: a study on silicone and human prostate tissue in vitro.2006Inngår i: Medical and Biological Engineering and Computing, ISSN 0140-0118, E-ISSN 1741-0444, Vol. 44, nr 7, s. 593-603Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Prostate cancer is the most common form of cancer in men in Europe and in the USA. Some prostate tumours are stiffer than the surrounding normal tissue, and it could therefore be of interest to measure prostate tissue stiffness. Resonance sensor technology based on piezoelectric resonance detects variations in tissue stiffness due to a change in the resonance frequency. An impression-controlled resonance sensor system was used to detect stiffness in silicone rubber and in human prostate tissue in vitro using two parameters, both combinations of frequency change and force. Variations in silicone rubber stiffness due to the mixing ratio of the two components could be detected (p<0.05) using both parameters. Measurements on prostate tissue showed that there existed a statistically significant (MANOVA test, p<0.001) reproducible difference between tumour tissue (n=13) and normal healthy tissue (n=98) when studying a multivariate parameter set. Both the tumour tissue and normal tissue groups had variations within them, which were assumed to be related to differences in tissue composition. Other sources of error could be uneven surfaces and different levels of dehydration for the prostates. Our results indicated that the resonance sensor could be used to detect stiffness variations in silicone and in human prostate tissue in vitro. This is promising for the development of a future diagnostic tool for prostate cancer.

  • 52.
    Jalkanen, Ville
    et al.
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskaplig fakultet, Centrum för medicinsk teknik och fysik.
    Andersson, Britt M
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskaplig fakultet, Centrum för medicinsk teknik och fysik.
    Bergh, Anders
    Umeå universitet, Medicinsk fakultet, Medicinsk biovetenskap.
    Ljungberg, Börje
    Umeå universitet, Medicinsk fakultet, Kirurgisk och perioperativ vetenskap.
    Lindahl, Olof A
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskaplig fakultet, Centrum för medicinsk teknik och fysik.
    Resonance sensor measurements of stiffness variations in prostate tissue in vitro: a weighted tissue proportion model2006Inngår i: Physiological Measurement, ISSN 0967-3334, E-ISSN 1361-6579, Vol. 27, nr 12, s. 1373-86Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Prostate cancer is the most common type of cancer in men in Europe and the US. The methods to detect prostate cancer are still precarious and new techniques are needed. A piezoelectric transducer element in a feedback system is set to vibrate with its resonance frequency. When the sensor element contacts an object a change in the resonance frequency is observed, and this feature has been utilized in sensor systems to describe physical properties of different objects. For medical applications it has been used to measure stiffness variations due to various patho-physiological conditions. In this study the sensor's ability to measure the stiffness of prostate tissue, from two excised prostatectomy specimens in vitro, was analysed. The specimens were also subjected to morphometric measurements, and the sensor parameter was compared with the morphology of the tissue with linear regression. In the probe impression interval 0.5-1.7 mm, the maximum R(2) > or = 0.60 (p < 0.05, n = 75). An increase in the proportion of prostate stones (corpora amylacea), stroma, or cancer in relation to healthy glandular tissue increased the measured stiffness. Cancer and stroma had the greatest effect on the measured stiffness. The deeper the sensor was pressed, the greater, i.e., deeper, volume it sensed. Tissue sections deeper in the tissue were assigned a lower mathematical weighting than sections closer to the sensor probe. It is concluded that cancer increases the measured stiffness as compared with healthy glandular tissue, but areas with predominantly stroma or many stones could be more difficult to differ from cancer.

  • 53.
    Jalkanen, Ville
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Andersson, Britt M.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Bergh, Anders
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk biovetenskap.
    Ljungberg, Börje
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Urologi och andrologi.
    Lindahl, Olof A.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Resonanssensorteknik för detektering av prostatacancer2010Inngår i: Medicinteknikdagarna 2010 / [ed] Ronnie Lundström, Umeå: Svensk förening för medicinsk teknik och fysik , 2010, s. 193-193Konferansepaper (Fagfellevurdert)
  • 54.
    Jalkanen, Ville
    et al.
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskaplig fakultet, Centrum för medicinsk teknik och fysik.
    Andersson, Britt M
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskaplig fakultet, Centrum för medicinsk teknik och fysik.
    Bergh, Anders
    Umeå universitet, Medicinsk fakultet, Medicinsk biovetenskap.
    Ljungberg, Börje
    Umeå universitet, Medicinsk fakultet, Kirurgisk och perioperativ vetenskap.
    Lindahl, Olof A
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskaplig fakultet, Centrum för medicinsk teknik och fysik.
    Spatial variations in prostate tissue histology as measured by a tactile resonance sensor2007Inngår i: Physiological Measurement, ISSN 0967-3334, E-ISSN 1361-6579, Vol. 28, nr 10, s. 1267-81Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In recent years, tactile sensors based on piezoelectric resonance sensor technology have been used for medical diagnosis where the sensor's stiffness-measuring properties can reflect tissue pathology. The change in the frequency of the resonating system and the change in force when contact is made with tissue are used as a stiffness parameter. Earlier stiffness measurements of prostate tissue in vitro demonstrate variations related to tissue composition. In this study, measured stiffness from two human prostate specimens was compared to histological composition of prostate tissue below and around the measurement points. Tissue stiffness was measured with the resonance sensor system. Tissue composition was measured at four different depths in the tissue specimen using a microscopic-image-based morphometrical method. With this method, the proportion of tissue types was determined at the points of intersections in a circular grid on the images representing each measurement point. Numerical values were used for weighting the tissue proportions at different depths in the tissue specimen. For an impression depth of 1.0 mm, the sensing depth in this study was estimated to be 3.5-5.5 mm. Stiffness variations due to horizontal tissue variations were investigated by studying the dependence of the size of the circular grid area relative to the contact area of the sensor tip. The sensing area (grid radius) was estimated to be larger than the contact area (contact radius) between the sensor tip and the tissue. Thus, the sensor tip registers spatial variations in prostate tissue histology, both directly below and lateral to the tip itself. These findings indicate that tumours around the sensor tip could be detected, which in turn supports the idea of a future resonance-sensor-based clinical device for detecting tumours and for guiding biopsies.

  • 55.
    Jalkanen, Ville
    et al.
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskaplig fakultet, Centrum för medicinsk teknik och fysik.
    Eklund, Anders
    Medicinsk teknik och informatik, Biomedical Engineering and Informatics, Umeå University Hospital.
    Lindahl, Olof
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskaplig fakultet, Centrum för medicinsk teknik och fysik.
    Force and frequency shift from a resonance sensor for detection of prostate cancer2003Inngår i: IFMBE Proceedings: World Congress on Medical Physics and Biomedical Engineering, Sydney, 2003Konferansepaper (Fagfellevurdert)
  • 56.
    Jalkanen, Ville
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Lindahl, Olof
    Dept. of Computer Science and Electrical Engineering (Systemteknik), Luleå University of Technology.
    Hand-held resonance sensor instrument for soft tissue stiffness measurements:  a first study on biological tissue in vitro2010Inngår i: IFMBE Proceedings of XII Mediterranean Conference on Medical and Biological Engineering and Computing, Heidelberg: Springer , 2010, s. 463-466Konferansepaper (Fagfellevurdert)
  • 57.
    Johannesson, Gauti
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk vetenskap, Oftalmiatrik.
    Hallberg, Per
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Ambarki, Khalid
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF). Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Eklund, Anders
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF). Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Linden, Christina
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk vetenskap, Oftalmiatrik.
    Age-dependency of ocular parameters - a cross sectional study of young and old healthy subjects2015Inngår i: Investigative Ophthalmology and Visual Science, ISSN 0146-0404, E-ISSN 1552-5783, Vol. 56, nr 7, artikkel-id Meeting Abstract: 116Artikkel i tidsskrift (Annet vitenskapelig)
    Abstract [en]

    Purpose: To investigate aging effect on ocular parameters inkluding intraocular pressure (IOP) measured with different tonometry methods in healthy young (HY) and elderly (HE) subjects.

    Methods: Fifty eyes of 50 HY subjects (28 females, 22-31 years of age) and 43 eyes of 43 HE subjects (22 females, 64-79 years of age) were included. IOP was measured with four tonometry methods in a standardized order: Ocular Response Analyser (ORA), Dynamic Contour Tonometry (DCT), Applanation Resonance Tonometry (ART) and Goldmann Applanation Tonometry (GAT). Other measurements included axial length (AL), central corneal thickness (CCT), corneal curvature (CC), ocular pulse amplitude (OPA) and aqueous humor (aq).

    Results: The mean IOP (HY/HE; mmHg ± standard deviation) was 13.9 ± 2.7/16.4 ± 3.4 with ORA, 15.1 ± 2.1/16.3 ± 3.1 with DCT, 12.3 ± 2.0/13.7 ± 2.8 with GAT and 13.1 ± 2.2/12.1 ± 2.5 with ART. IOP was significantly higher (difference ± standard error) in HE compared to HY measured with ORA (+2.5 mmHg ± 0.6), GAT (+1.4 ± 0.5) and DCT (+1.2 ± 0.6). There was a trend towards lower IOP in HE when measured with ART (-1.0 ± 0.5, p=0.05). There was no difference between HE and HY in CCT, CC, AL or OPA.

    Conclusions: Tonometry methods are affected differently by age. IOP was measured higher in elderly people with ORA, DCT and GAT in this Scandinavian population. This effect was not seen in measurements with ART. Other ocular parameters did not differ between the age groups indicating that these measured parameters are not influenced by age in this population.

  • 58.
    Johannesson, Gauti
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk vetenskap, Oftalmiatrik.
    Hallberg, Per
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Ambarki, Khalid
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF). Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Eklund, Anders
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF). Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Linden, Christina
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk vetenskap, Oftalmiatrik.
    Age-dependency of ocular parameters: a cross sectional study of young and elderly healthy subjects2015Inngår i: Graefe's Archives for Clinical and Experimental Ophthalmology, ISSN 0721-832X, E-ISSN 1435-702X, Vol. 253, nr 11, s. 1979-1983Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    To investigate the effect of aging on ocular parameters, including intraocular pressure (IOP), measured with different tonometry methods in healthy young (HY) and healthy elderly (HE) subjects and to study the effect of corneal parameters on tonometry methods. In this prospective, cross-sectional study, fifty eyes of 50 HY subjects (28 females, 22-31 years of age) and 43 eyes of 43 HE subjects (22 females, 64-79) were included. IOP was measured with four tonometry methods in a standardized order: ocular response analyser (ORA), dynamic contour tonometry (DCT), applanation resonance tonometry (ART) and Goldmann applanation tonometry (GAT). Other measurements included axial length (AL), central corneal thickness (CCT), corneal curvature (CC), anterior chamber volume (ACV), corneal hysteresis (CH) and corneal resistance factor (CRF). The mean IOP (HY/HE; mmHg +/- standard deviation (SD)) was 12.2 +/- 2.2/14.1 +/- 3.5 with GAT. IOP was significantly higher (difference +/- standard error) in HE compared to HY measured with an ORA (+3.1 mmHg +/- 0.6), GAT (+1.9 +/- 0.6) and DCT (+1.6 +/- 0.6). No significant difference was found in IOP measured with ART. CH and ACV were significantly lower in HE compared to HY. There was no difference between the groups in CCT, CC, AL or CRF. No tonometry method was dependant on CCT or CC. IOP measured with an ORA and via DCT and GAT was higher in HE compared to HY Swedish subjects, while IOP measured with ART did not differ between the groups. In these homogeneous groups, tonometry methods were independent of CCT and CC.

  • 59.
    Johansson, Anna-Maria
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för samhällsmedicin och rehabilitering, Fysioterapi.
    Grip, Helena
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Strong, Andrew
    Umeå universitet, Medicinska fakulteten, Institutionen för samhällsmedicin och rehabilitering, Fysioterapi.
    Selling, Jonas
    Umeå universitet, Medicinska fakulteten, Institutionen för samhällsmedicin och rehabilitering, Fysioterapi.
    Rönnqvist, Louise
    Umeå universitet, Samhällsvetenskapliga fakulteten, Institutionen för psykologi.
    Boraxbekk, Carl-Johan
    Umeå universitet, Medicinska fakulteten, Umeå centrum för funktionell hjärnavbildning (UFBI). Umeå universitet, Samhällsvetenskapliga fakulteten, Demografiska databasen.
    Häger, Charlotte
    Umeå universitet, Medicinska fakulteten, Institutionen för samhällsmedicin och rehabilitering, Fysioterapi.
    Finger movement control and associated brain activity responses post-stroke2016Inngår i: XXI ISEK Congress, 2016Konferansepaper (Fagfellevurdert)
    Abstract [en]

    BACKGROUND AND AIM: Impaired finger dexterity is common after stroke, often affecting activities of daily living. Knowledge of kinematic characteristics and of underlying neurological mechanisms of such impairments is important to understand functional recovery. This study aims to investigate finger movement control and related brain activity patterns post-stroke (PS). METHODS: Data from a subsample including 9 participants PS with residual hemiparesis affecting manual dexterity (M age- 66; 3 female) and 12 able-bodied control (C) participants (M age- 65; 3 female) were analyzed. Two series of self-paced cyclic finger extension-flexion movements in random order were performed for each hand (4 series with vision, V, and 4 without vision, NV). Optoelectronic cameras monitored the 3D movement of markers affixed to the fingertips. Motion data was used to calculate each finger's individuation index (II), reflecting movement independence, each finger's Stationarity index (SI), reflecting the ability to keep the finger still while another moves [1] and Movement frequency (MF). Functional magnetic resonance imaging, with simultaneous movement recording, was used to investigate brain activity patterns in relation to the kinematic parameters. II, SI, MF and the effect of vision were analyzed for the 4th digit. RESULTS: A factorial ANOVA 2 [group] x 2 [condition] x 2 [side] x [index type] showed an effect for group (p < .0001; PS < C); condition (p < .01; NV < V); side (p < .0001; affected/non-preferred < non-affected/preferred); and index type (p < .0001; SI < II). An interaction between group and side (p < .01) showed that indices of the affected side were lower compared to the non-affected side within the PS group and compared to both sides in the C group. No significant effects were apparent for MF but significant correlations were found between the indices and MF that were restricted to the PS group alone (over all conditions- r = -0.22; p < .01; within the NV condition- r = -0.19; p < .01; within the affected side r = -0.15; p < .05; and within the SI categorization r = -0.14; p < .05). Furthermore, within NV for the non-affected hand on the SI alone (r = -0.54; p < .05). All indicate that slower movements had higher indices. DISCUSSION: The associations between slower MF and higher index values within the PS group were located to conditions with increased difficulty (NV, affected side, and SI). Thus, reducing speed may be a selected strategy to increase control of finger movements PS when the demand on motor control is high. Further, with the applied calculation of finger movement independence we were able detect group differences, side differences within the PS group, and a positive effect of vision of the hands during performance. This indicates that this calculation is a sensitive measure that could be used to study the effects of stroke and to monitor progression in motor recovery. [1] Häger-Ross & Schieber, 2000, J Neurosci 20:8542-50

  • 60.
    Johansson, Elias
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för farmakologi och klinisk neurovetenskap, Klinisk neurovetenskap.
    Ambarki, Khalid
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Birgander, Richard
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper.
    Bahrami, Nazila
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper.
    Eklund, Anders
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Malm, Jan
    Umeå universitet, Medicinska fakulteten, Institutionen för farmakologi och klinisk neurovetenskap, Klinisk neurovetenskap.
    Cerebral microbleeds in idiopathic normal pressure hydrocephalus2016Inngår i: Fluids and Barriers of the CNS, ISSN 2045-8118, E-ISSN 2045-8118, Vol. 13, artikkel-id 4Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Background: A vascular disease could be involved in pathophysiology of normal pressure hydrocephalus (INPH). If so, there should be an association between INPH and cerebral microbleeds (CMB). This study aims to analyze if CMB are associated with INPH.

    Methods: In this case-control study we included 14 patients with INPH (mean age 76 years, 60 % female) and 41 healthy controls (HeCo; mean age 71 years, 60 % female). All were investigated with magnetic resonance imaging (MRI) using a T2*-sequence. The MRI exams were reviewed by two neuroradiologists for the presence of CMBs; the prevalence of findings of two or more CMBs was compared between INPH group and control group. After investigation, INPH patients underwent shunt surgery.

    Results: Two or more CMB were detected more frequently in the INPH group compared to HeCo (n = 6, 43 % vs. n = 4, 10 %; p = 0.01). Among the participants where MRI revealed CMB, the number of CMB was higher among the INPH patients than the HeCo (median 8; IQR 2-34 vs. median 1; IQR 1-2; p = 0.005).

    Conclusions: This study supports a vascular component to the pathophysiology of INPH.

  • 61.
    Jonsson, Ulf G.
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Andersson, Britt M.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Lindahl, Olof A.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    A FEM-Based Method Using Harmonic Overtones to Determine the Effective Elastic, Dielectric, and Piezoelectric Parameters of Freely Vibrating Thick Piezoelectric Disks2013Inngår i: IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control, ISSN 0885-3010, E-ISSN 1525-8955, Vol. 60, nr 1, s. 243-255Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    To gain an understanding of the electroelasticproperties of tactile piezoelectric sensors used in the characterizationof soft tissue, the frequency-dependent electric impedanceresponse of thick piezoelectric disks has been calculatedusing finite element modeling. To fit the calculated to the measuredresponse, a new method was developed using harmonicovertones for tuning of the calculated effective elastic, piezoelectric,and dielectric parameters. To validate the results, theimpedance responses of 10 piezoelectric disks with diameterto-thickness ratios of 20, 6, and 2 have been measured from10 kHz to 5 MHz. A two-dimensional, general purpose finiteelement partial differential equation solver with adaptive meshingcapability run in the frequency-stepped mode, was used.The equations and boundary conditions used by the solver arepresented. Calculated and measured impedance responses arepresented, and resonance frequencies have been compared indetail. The comparison shows excellent agreement, with averagerelative differences in frequency of 0.27%, 0.19%, and0.54% for the samples with diameter-to-thickness ratios of 20,6, and 2, respectively. The method of tuning the effective elastic,piezoelectric, and dielectric parameters is an importantstep toward a finite element model that describes the propertiesof tactile sensors in detail.

  • 62.
    Jonsson, Ulf G
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Detecting Inclusions in a Silicone Rubber Phantom Using Standing Lamb Waves and Multiple Frequency Footprints2014Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    The thesis deals with one major question: is it possible, using one piezoelectric sensor/vibrator, to detect a hard inclusion in a silicone rubber phantom? The question was approached with an open mind and the task was subdivided into three clearly identifiable parts: characterization of the piezoelectric sensor/vibrator (paper I), creating a model of the visco-elastic properties of a tissue-like material (phantom) in contact with the sensor/vibrator (paper II), and to detect the presence of a hard inclusion in the phantom (paper III). All vibrations of the sensor/vibrator and phantom was modeled using a finite element method (FEM). To minimize the computational time and to maximize the FEM model's ability to correctly reproduce the vibrations, a two-dimensional model system consisting of a cylindrical piezoelectric sensor/vibrator, emitting radial elastic waves in to a cylindrical disk-shaped phantom, was chosen. The piezoelectric sensor/vibrator was characterized using a parameter tuning procedure using harmonic overtones. The procedure enables tuning of the electro-elastic parameters of the sensor/vibrator so that the measured and calculated impedance frequency responses match. Silicone rubber was chosen as a phantom to mimic soft tissue. The properties of the phantom was modeled using a fractional derivative visco-elastic model. The hyperelastic effect at the first radial resonance of the sensor vibrator was corrected for by a compensating function. The high frequency complex visco-elastic modulus of the silicone rubber was determined using the transitions of standing Lamb waves in the phantom. The presence of a ring-shaped inclusion in the phantom, of polyamide, was detected using the change of the transitional Lamb wave patterns in the phantom. The tuning of the PZT5A1 sensor/vibrator parameters yielded a match between the calculated and the measured impedance spectra better than 0.54%. The average, complex, elastic modulus of three silicone rubber, Silgel 612, samples were: (0.97 + 0.009i) GPa  at 100 kHz and (0.97 + 0.005i) GPa at 250 kHz. The presence of a polyamide inclusion, PA6GPE, was detected in the phantom using multiple frequency footprints.

  • 63.
    Jonsson, Ulf G
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Lindahl, Olof A
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF). Dept. of Engineering Sciences and Mathematics, Luleå University of Technology, Sweden.
    Andersson, Britt M
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Modeling the high-frequency complex modulus of a silicone rubber using standing lamb waves and an inverse finite element method2014Inngår i: IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control, ISSN 0885-3010, E-ISSN 1525-8955, Vol. 61, nr 12, s. 2106-2120Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    To gain an understanding of the high-frequency elastic properties of silicone rubber, a finite element model of a cylindrical piezoelectric element, in contact with a silicone rubber disk, was constructed. The frequency dependent elastic modulus of the silicone rubber was modeled by a four parameter fractional derivative viscoelastic model in the 100 kHz to 250 kHz frequency range. The calculations were carried out in the range of the first radial resonance frequency of the sensor. At the resonance, the hyperelastic effect of the silicone rubber was modeled by a hyperelastic compensating function. The calculated response was matched to the measured response by using the transitional peaks in the impedance spectrum that originates from the switching of standing Lamb wave modes in the silicone rubber. To validate the results, the impedance responses of three 5 mm thick silicone rubber disks, with different radial lengths, were measured. The calculated and measured transitional frequencies have been compared in detail. The comparison showed very good agreement, with average relative differences of 0.7 %, 0.6 %, and 0.7 % for the silicone rubber samples with radial lengths of 38.0 mm, 21.4 mm, and 11.0 mm, respectively. The average, complex, elastic modulus of the samples were: (0.97 + 0.009i) GPa at 100 kHz and (0.97 + 0.005i) GPa at 250 kHz.

  • 64.
    Jonsson, Ulf G
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Lindahl, Olof A
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF). Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper.
    Andersson, Britt M.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Using a look-up table technique and finite element calculations for quick detection of stiff inclusions in silicone rubber2020Inngår i: Engineering computations, ISSN 0264-4401, E-ISSN 1758-7077Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Purpose: The aim of the study was to show that a new method, using a look-up table technique, can be used to detect the presence and position of an inclusion embedded in a tissue-like material. Due to the time-consuming nature of the finite element (FE) method or FEM, real-time applications involving FEM as part of a control loop, are traditionally limited to slowly varying systems. By using a simplified two-dimensional FE model and a look-up table, we show by simulations and experiments that it is possible to achieve reasonable computational times in a tactile resonance sensor application.

    Design/methodology/approach: A piezoelectric disk was placed in the center of a silicone rubber disk (SRD) with viscoelastic properties, where it acted as both sensor and actuator and dissipated radial acoustic waves into the silicone. The look-up table was constructed by calculating the radial Lamb wave transition frequencies in the impedance frequency response of the sensor while varying the position of an inclusion. A position-matching algorithm was developed that matched measured and calculated Lamb wave transitions and thereby identified the presence and position of an inclusion.

    Findings: In an experiment, the position of a hard inclusion was determined by measuring the Lamb transition frequencies of the first radial resonance in two SRDs. The result of the matching algorithm for Disk 1 was that the matched position was less than 3% from the expected value. For Disk 2, the matching algorithm erroneously reported two false positions before reporting a position that was less than 5% from the expected value. An explanation for this discrepancy is presented. In a verifying experiment, the algorithm identified the condition with no inclusion present.

    Originality/value: The approach outlined in this work, adds to the prospect of developing time-sensitive diagnostic instruments. This approach has the potential to provide a powerful technique to quickly present spatial information on detected tumors.

  • 65.
    Jonsson, Ulf G
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Lindahl, Olof A.
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF). Dept. of Engineering Sciences and Mathematics, Luleå University of Technology, Sweden.
    Andersson, Britt M.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Using Standing Lamb waves and the Finite Element Method to Detect Hard Inclusions in Silicone Rubber DisksManuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    The presence of an inclusion in a cylindrical silicone rubber disk is determined using FEM, standing Lamb waves, and an algorithm using multiple frequency footprints. Radial elastic waves are emitted into the disk by a cylindrical piezoelectric sensor placed in the center of the disk. The visco-elastic properties of the silicone rubber disk is modeled by a fractional derivative model and the hyperelastic effect at the radial resonance frequency was compensated for. Using the finite element model, the Lamb wave transition frequencies in the impedance frequency response of the sensor was calculated for a specified position of the inclusion. The set of frequencies was named the footprint for that position. The position of the inclusion was varied between 0.05 to 0.95, with a step of 0.01, of the radial length of the silicone rubber disk. For each position, a footprint was calculated. The footprints,s, with corresponding positions, were stored in a database. A positioning algorithm was developed that could match an unknown footprint to a footprint in the database. A self-test of the algorithm showed that the correct position was found for 94% of the tested positions. The results of the positioning algorithm was that the presence of the inclusions were detected, and that the positions of the inclusions at 0.38 and 0.63 were estimated by the positioning algorithm as: 0.45 and 0.74, with relative errors +18% and +17% respectively. The positions are given as the ratio of the radius of the inclusion to the silicone rubber disk radius.

  • 66.
    Jóhannesson, Gauti
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk vetenskap, Oftalmiatrik.
    Hallberg, Per
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Eklund, Anders
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Lindén, Christina
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk vetenskap, Oftalmiatrik.
    Pascal, ICare and Goldmann applanation tonometry: a comparative study2008Inngår i: Acta ophthalmologica, ISSN 1755-3768, Vol. 86, nr 6, s. 614-621Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    PURPOSE: To compare intraocular pressure (IOP) measurements by Pascal, ICare and Goldmann applanation tonometry (GAT), to evaluate the effects of central corneal thickness (CCT) and curvature on IOP measurement and to estimate the intra-observer variability.

    METHODS: A prospective, single-centre study of 150 eyes with a wide range of pressures. Six masked IOP measurements/method; corneal thickness and curvature were studied for each eye. GAT was the reference.

    RESULTS: IOPPascal and IOPICare correlated with IOPGAT (r = 0.91, 0.89). Mean ICare measurement exceeded GAT by 2 mmHg. Pascal measured higher than GAT at low IOPs and lower at high IOPs. For every 10 mmHg increase in IOP above 31 mmHg, Pascal measured 2 mmHg lower than GAT and vice versa. CCT was correlated significantly with IOPGAT (r = 0.23) and IOPICare (r = 0.43) but not with IOPPascal (P = 0.12). CCT was correlated with age. In a subgroup (>50 years), ICare and the difference between IOPGAT and IOPPascal were affected significantly by the CCT, whereas IOPGAT and IOPPascal were not. Corneal curvature was correlated significantly with IOPGAT (r = -0.27) and IOPPascal (r = -0.26) but not with IOPICare (P = 0.60). Intra-observer variability within each set of six measurements was approximately 2 mmHg, irrespective of method.

    CONCLUSION: This study showed a reasonable overall correlation and concordance between the IOP obtained with the three instruments. None of the methods were completely independent of the biomechanical properties of the cornea. ICare showed a significant dependency upon CCT, whereas GAT and Pascal showed a significant dependency on corneal curvature. All methods showed intra-observer variability, which leaves room for further improvement of methods.

  • 67.
    Karlsson, Stefan
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Yu, Jun
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Matematisk statistik.
    Estimation of surface electromyogram spectral alteration using reduced-order autoregressive model2000Inngår i: Medical and Biological Engineering and Computing, ISSN 0140-0118, E-ISSN 1741-0444, Vol. 38, s. 520-527Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A new method is proposed, based on the pole phase angle (PPA) of a second-order autoregressive (AR) model, to track spectral alteration during localised muscle fatigue when analysing surface myo-electric (ME) signals. Both stationary and non-stationary, simulated and real ME signals are used to investigate different methods to track spectral changes. The real ME signals are obtained from three muscles (the right vastus lateralis, rectus femoris and vastus medialis) of six healthy male volunteers, and the simulated signals are generated by passing Gaussian white-noise sequences through digital filters with spectral properties that mimic the real ME signals. The PPA method is compared, not only with spectra-based methods, such as Fourier and AR, but also with zero crossings (ZCs) and the first AR coefficient that have been proposed in the literature as computer efficient methods. By comparing the deviation (dev), in percent, between the linear regression of the theoretical and estimated mean frequencies of the power spectra for simulated stationary (s) and non-stationary (ns) signals, in general, it is found that the PPA method (dev(s) = 4.29; dev(ns) = 1.94) gives a superior performance to ZCs (dv(s) = 8.25) and the first AR coefficient (4.18<dev(s)<21.8; 0.98<dev(ns)<4.36) but performs slightly worse than spectra-based methods (0.33<dev(s)<0.79; 0.41<dev(ns)<1.07). However, the PPA method has the advantage that it estimates spectral alteration without calculating the spectra and therefore allows very efficient computation.

  • 68. Kleyko, Denis
    et al.
    Hostettler, Roland
    Lyamin, Nikita
    Birk, Wolfgang
    Wiklund, Urban
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Osipov, Evgeny
    Vehicle Classification using Road Side Sensors and Feature-free Data Smashing Approach2016Inngår i: 2016 IEEE 19TH INTERNATIONAL CONFERENCE ON INTELLIGENT TRANSPORTATION SYSTEMS (ITSC), IEEE, 2016, s. 1988-1993Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The main contribution of this paper is a study of the applicability of data smashing - a recently proposed data mining method - for vehicle classification according to the "Nordic system for intelligent classification of vehicles" standard, using measurements of road surface vibrations and magnetic field disturbances caused by passing vehicles. The main advantage of the studied classification approach is that it, in contrast to the most of traditional machine learning algorithms, does not require the extraction of features from raw signals. The proposed classification approach was evaluated on a large dataset consisting of signals from 3074 vehicles. Hence, a good estimate of the actual classification rate was obtained. The performance was compared to the previously reported results on the same problem for logistic regression. Our results show the potential trade-off between classification accuracy and classification method's development efforts could be achieved.

  • 69.
    Klinth, Jeanna E
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik. Umeå universitet, Medicinska fakulteten, Umeå Centre for Microbial Research (UCMR). Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för molekylärbiologi (Teknisk-naturvetenskaplig fakultet). Umeå universitet, Medicinska fakulteten, Molekylär Infektionsmedicin, Sverige (MIMS). Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Pinkner, Jerome S
    Hultgren, Scott J
    Almqvist, Fredrik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Umeå universitet, Medicinska fakulteten, Umeå Centre for Microbial Research (UCMR).
    Uhlin, Bernt Eric
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för molekylärbiologi (Teknisk-naturvetenskaplig fakultet). Umeå universitet, Medicinska fakulteten, Umeå Centre for Microbial Research (UCMR). Umeå universitet, Medicinska fakulteten, Molekylär Infektionsmedicin, Sverige (MIMS). Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten).
    Axner, Ove
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik. Umeå universitet, Medicinska fakulteten, Umeå Centre for Microbial Research (UCMR). Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Impairment of the biomechanical compliance of P pili: a novel means of inhibiting uropathogenic bacterial infections?2012Inngår i: European Biophysics Journal, ISSN 0175-7571, E-ISSN 1432-1017, Vol. 41, nr 3, s. 285-295Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Gram-negative bacteria often initiate their colonization by use of extended attachment organelles, so called pili. When exposed to force, the rod of helix-like pili has been found to be highly extendable, mainly attributed to uncoiling and recoiling of its quaternary structure. This provides the bacteria with the ability to redistribute an external force among a multitude of pili, which enables them to withstand strong rinsing flows, which, in turn, facilitates adherence and colonization processes critical to virulence. Thus, pili fibers are possible targets for novel antibacterial agents. By use of a substance that compromises compliance of the pili, the ability of bacteria to redistribute external forces can be impaired, so they will no longer be able to resist strong urine flow and thus be removed from the host. It is possible such a substance can serve as an alternative to existing antibiotics in the future or be a part of a multi-drug. In this work we investigated whether it is possible to achieve this by targeting the recoiling process. The test substance was purified PapD. The effect of PapD on the compliance of P pili was assessed at the single organelle level by use of force-measuring optical tweezers. We showed that the recoiling process, and thus the biomechanical compliance, in particular the recoiling process, can be impaired by the presence of PapD. This leads to a new concept in the search for novel drug candidates combating uropathogenic bacterial infections-"coilicides", targeting the subunits of which the pilus rod is composed.

  • 70.
    Koskinen, Lars-Owe
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för farmakologi och klinisk neurovetenskap, Klinisk neurovetenskap.
    Sundstrom, Nina
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Brorsson, Camilla
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap.
    Olivecrona, M.
    SECONDARY PEAK OF S-100B IS ASSOCIATED WITH DECOMPRESSIVE HEMICRANIECTOMY2016Inngår i: Journal of Neurotrauma, ISSN 0897-7151, E-ISSN 1557-9042, Vol. 33, nr 3, s. A27-A27Artikkel i tidsskrift (Annet vitenskapelig)
    Abstract [en]

    S-100B is a tissue biomarker for brain injury and secondary peak of S-100B (SP) is associated with outcome. Little is known whether SP is associated with decompressive hemicraniectomy (DC).

  • 71.
    Lenfeldt, Niklas
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för farmakologi och klinisk neurovetenskap, Klinisk neurovetenskap. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF). Neurologi.
    Hauksson, Jón
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Birgander, Richard
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Diagnostisk radiologi.
    Eklund, Anders
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Malm, Jan
    Umeå universitet, Medicinska fakulteten, Institutionen för farmakologi och klinisk neurovetenskap, Klinisk neurovetenskap. Neurologi.
    Improvement after cerebrospinal fluid drainage is related to levels of N-acetyl-aspartate in idiopathic normal pressure hydrocephalus2008Inngår i: Neurosurgery, ISSN 0148-396X, E-ISSN 1524-4040, Vol. 62, nr 1, s. 135-142Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    OBJECTIVE: This study uses proton magnetic resonance spectroscopy to investigate whether or not idiopathic normal pressure hydrocephalus is associated with neuronal dysfunction or ischemia in the brain. We evaluate whether or not proton magnetic resonance spectroscopy is useful for predicting improvement after long-term external lumbar drainage (ELD) of cerebrospinal fluid.

    METHODS: Eighteen patients (mean age, 73 yr; six women) and 10 matching controls participated. Participants were characterized by clinical features, cognitive and motor function tests, and cerebrospinal fluid hydrodynamics (patients only). Signals from N-acetyl-aspartate (NAA), choline, lactate, and creatine (Cr) (reference) were sampled once in controls and twice in patients (before and after a 3-day ELD of approximately 135 mL/24 h) by proton magnetic resonance spectroscopy (1.5 T) from a 7.2-mL volume in the frontal white matter. Improvement was defined by video recordings of the patients' gait.

    RESULTS: Sixteen patients finished the ELD (one patient had meningitis, and one patient had catheter insertion failure) with a mean drain volume of 395 mL. NAA/Cr ratios were lower in patients than in controls (1.60 versus 1.84, P = 0.02), but no difference was found for choline/Cr ratios. No lactate signals were detected. Fifty percent of patients improved after ELD. They had higher NAA/Cr ratios than nonimproved patients (1.70 versus 1.51, P = 0.01), but no differences were found in choline/Cr ratios or drain volume.

    CONCLUSION: NAA/Cr ratios were decreased in patients with idiopathic normal pressure hydrocephalus, which is consistent with neuronal dysfunction in the frontal white matter. Improved patients had NAA/Cr ratios close to normal, indicating that enough functional neurons are a prerequisite for the cerebrospinal fluid drainage to have an effect.

  • 72.
    Lenfeldt, Niklas
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för farmakologi och klinisk neurovetenskap, Klinisk neurovetenskap.
    Larsson, Anne
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Nyberg, Lars
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Diagnostisk radiologi. Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi.
    Birgander, Richard
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Diagnostisk radiologi.
    Eklund, Anders
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF). Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Malm, Jan
    Umeå universitet, Medicinska fakulteten, Institutionen för farmakologi och klinisk neurovetenskap, Klinisk neurovetenskap.
    Diffusion tensor imaging reveals supplementary lesions to frontal white matter in Idiopathic normal pressure hydrocephalus2011Inngår i: Neurosurgery, ISSN 0148-396X, E-ISSN 1524-4040, Vol. 68, nr 6, s. 1586-1593Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    BACKGROUND:: Idiopathic normal pressure hydrocephalus (INPH) is associated with white matter lesions, but the extent and severity of the lesions do not cohere with symptoms or improvement after shunting, implying the presence of further, yet undisclosed, injuries to white matter in INPH. OBJECTIVE:: To apply diffusion tensor imaging (DTI) to explore white matter lesions in patients with INPH before and after drainage of cerebrospinal fluid (CSF). METHODS:: Eighteen patients and ten controls were included. DTI was performed in a 1.5T MRI scanner before and after three-day drainage of 400 ml of CSF. Regions of interest included corpus callosum, capsula interna, frontal and lateral periventricular white matter, and centrum semiovale. White matter integrity was quantified by assessing fractional anisotropies (FA) and apparent diffusion coefficients (ADC), comparing them between patients and controls and between patients before and after drainage. The significance level corresponded to 0.05 (Bonferroni corrected). RESULTS:: Decreased FA in patients was found in three regions (p<0.002, p<0.001 and p<0.0001) in anterior frontal white matter, whereas elevated ADC was found in genu corpus callosum (p<0.0001) and areas of centrum semiovale associated to the precentral gyri (p<0.002). Diffusion patterns in these areas did not change after drainage. CONCLUSION:: DTI reveals subtle injuries - interpreted as axonal loss and gliosis - to anterior frontal white matter where high-order motor systems between frontal cortex and basal ganglia travel, further supporting the notion that motor symptoms in INPH are caused by a chronic ischemia to the neuronal systems involved in the planning processes of movements.

  • 73.
    Lindahl, O A
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Constantinou, C E
    Eklund, Anders
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Murayama, Y
    Hallberg, Per
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Omata, S
    Tactile resonance sensors in medicine.2009Inngår i: Journal of Medical Engineering & Technology, ISSN 0309-1902, E-ISSN 1464-522X, Vol. 33, nr 4, s. 263-273Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Tactile sensors in general are used for measuring the physical parameters associated with contact between sensor and object. Tactile resonance sensors in particular are based on the principle of measuring the frequency shift, Deltaf, defined as the difference between a freely vibrating sensor resonance frequency and the resonance frequency measured when the sensor makes contact to an object. Deltaf is therefore related to the acoustic impedance of the object and can be used to characterize its material properties. In medicine, tactile resonance sensor systems have been developed for the detection of cancer, human ovum fertility, eye pressure and oedema. In 1992 a Japanese research group published a paper presenting a unique phase shift circuit to facilitate resonance measurements. In this review we summarize the current state-of-the-art of tactile resonance sensors in medicine based on the phase shift circuit and discuss the relevance of the measured parameters for clinical diagnosis. Future trends and applications enabled by this technology are also predicted.

  • 74.
    Lindahl, Olof A
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF). Luleå University of Technology,.
    From biomedical research to viable products on the health care market: a North Sweden model called CMTF2009Inngår i: IFMBE Proceedings / [ed] Olaf Dössel & Wolfgang C. Schlegel, Springer, 2009, Vol. 25/12, nr 12, s. 127-130Konferansepaper (Fagfellevurdert)
    Abstract [en]

    A centre for research in Biomedical engineering and physics (CMTF) has been built up in Northern Sweden. The CMTF has resulted in increased growth of the biomedical engineering activities both in academia and in the industry in Northern Sweden. Fore example six new companies have resulted from the research. Cooperation was built up between the CMTF and 15 established companies. A research company for business development of the research results from the centre has been established and is owned by the project managers in the centre. The company is called CMTF Business Development Co Ltd and it has also increased the interest for business development questions among the scientists in the centre, i.e. encouraged entrepreneurship.

  • 75.
    Lindahl, Olof A.
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF). Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper. Institutionen för teknikvetenskap och matematik, Luleå tekniska universitet.
    Nyberg, Morgan
    Institutionen för teknikvetenskap och matematik, Luleå tekniska universitet.
    Jalkanen, Ville
    Department of engineering sciences and mathematics, Luleå University of Technology, Luleå, Sweden.
    Ramser, Kerstin
    Institutionen för teknikvetenskap och matematik, Luleå tekniska universitet.
    Prostate cancer detection using a combination of Raman spectroscopy and stiffness sensing2015Inngår i: 1st Global Conference on Biomedical Engineering and 9th Asian-Pacific Conference on Medical and Biological Engineering: October 9-12, 2014, Tainan, Taiwan / [ed] Fong-Chin Su, Shyh-Hau Wang, Ming-Long Yeh, Springer International Publishing , 2015, s. 267-270Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Prostate cancer (PCa) is the most common cancer form for men in Europe. A sensor system combining Raman spectroscopy and stiffness sensing with a resonance sensor has recently been developed by us for prostate cancer detection. In this study the sensor system has been used for measurements on two slices of fresh human prostate tissue. The stiffness sensor could detect locations slices with significantly different stiffness contrasts (p < 0.05). Raman spectroscopic measurements could be performed with the dual-modality probe for tissue classification. The findings are important for the continued development of a combination probe for prostate cancer detection.

  • 76.
    Lindahl, Olof A
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF). Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper.
    Ramser, K.
    Bäcklund, Tomas
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Ljungberg, Börje
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Urologi och andrologi.
    Bergh, Anders
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk biovetenskap, Patologi.
    Prostate cancer detection ex vivo combining Raman spectroscopy and tactile resonance technology2018Inngår i: EMBEC & NBC 2017 / [ed] Eskola, H Vaisanen, O Viik, J Hyttinen, J, SPRINGER-VERLAG SINGAPORE PTE LTD , 2018, s. 193-196Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Prostate cancer is the most common cancer for men in the western world. The most prevalent curative treatment is radical prostatectomy. However, prostate surgery can give unwanted side effects and there is a need for an instrument that can provide decision support to the surgeon during surgery on the presence of cancer cells in the surgical margin. A dual modality probe, combining Raman spectroscopy and tactile resonance technology, has been used for detecting cancer in fresh human prostate tissue. The tactile resonance modality measures the tissue stiffness and Raman spectroscopy depicts the molecular content in tissue, both related to cancer. After ethical approval, the study investigated the potential of the dual-modality probe by testing its ability to differentiate between normal and cancerous prostate tissue ex vivo. It also investigated the minimal amount of measurement points needed to securely detect cancer on the surface of prostate tissue. Measurements on three prostate tissue slices show that the tactile resonance modality measuring stiffness was able to detect differences between normal and cancerous tissue on a significant level of 90%, but the sample size was too low to draw any firm conclusions. It was also suggested from the study results that the high wavenumber region in the Raman spectrum can give valuable information about cancer in prostate tissue. A number of 24 measurement points were enough for detecting cancer in prostate slices in this study. It can be suggested from this study that combining these two sensor modalities is promising for accurate detection of prostate cancer that is needed during prostate surgery, but more measurements including more prostates must be performed before the full value of the study result can be established.

  • 77.
    Lindahl, Olof
    et al.
    Luleå tekniska universitet.
    Andersson, Britt
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Karlsson, Stefan
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper.
    Lundström, Ronnie
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Yrkes- och miljömedicin.
    Ramser, Kerstin
    Luleå tekniska universitet.
    Från forskningside till kommersiell produkt på marknaden: CMTF, ett framgångsexempel2009Inngår i: Medicinteknikdagarna 2009, Svensk förening för medicinsk teknik och fysik , 2009, s. 17-Konferansepaper (Fagfellevurdert)
  • 78.
    Lindahl, Olof
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik. Luleå tekniska universitet.
    Andersson, Britt
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Lundström, Ronnie
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Hallberg, Josef
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF). Luleå tekniska universitet.
    A Triple-Helix model for refining biomedical engineering research into spin-off companies for the health care market2013Inngår i: World Congress on Medical Physics and Biomedical Engineering May 26-31, 2012, Beijing, China / [ed] Mian Long, Springer, 2013, s. 2088-2090Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Triple-Helix activities at the centre for biomedical engineering and physics (CMTF) have generated growth both in academia at the universities and in the industry in Northern Sweden. Cooperation was built up between the 26 research projects and about 15 established companies in the field of biomedical engineering. The established researcher - owned company for business development of the research results from the CMTF, CMTF Business Development Co Ltd, has so far launched one spin-off company and has 15 new business leads to business develop. The activities have also increased the interest for commercial and entrepreneurship questions among the scientists in the centre. So far a total of seven spin-off companies have resulted from the CMTF-research since the year 2000.

  • 79.
    Lindahl, Olof
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Andersson, Britt
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Lundström, Ronnie
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF). Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper.
    Hallberg, Josef
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    A tripple-helix model for refining biomedical engineering research into innovations and spin-off companies2012Inngår i: Medicinteknikdagarna 2012, 2012Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Triple-Helix activities within the center for biomedical engineering and physics (CMTF) have generated growth in academic research as well as industry in Northern Sweden in the field of biomedical engineering. Currently CMTF holds 26 ongoing research projects involving more than 150 researchers. So far a total of eight spin-off companies have resulted from research in CMTF since the year 2000. A researcher-owned company, CMTF Business Development Co Ltd, has been established for business development of the research results from the CMTF, which so far have launched two spin-off companies and 15 new business leads for business development. The activities have also increased the interest for innovations and entrepreneurship among the scientists in the center.

  • 80.
    Lindahl, Olof
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Andersson, Britt
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Lundström, Ronnie
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Ramser, Kerstin
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    From biomedical research to spin-off companies for the health care market2010Inngår i: The XII Mediterranean Conference on Medical and Biological Engineering and Computing: vol. 29, part 4, Springer, 2010, s. 624-626Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Through research at the centre for biomedical engineering and physics (CMTF) seven new companies have been established in Northern Sweden. The activities have generated growth both in academia at the universities and in the industry in Northern Sweden. Cooperation was built up between the 23 research projects and more than 20 established companies in the field of biomedical engineering. A researcher-owned company for business development of the research results from the CMTF has been established, CMTF Business Development Co Ltd, and has launched its first spin-off company in the autumn 2009. It has also increased the interest for commercial and entrepreneurship questions among the scientists in the centre. So far seven spin-off companies have resulted from the CMTF-research.

  • 81.
    Lindberg, Peter
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Andersson, Britt M.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Bergh, Anders
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk biovetenskap.
    Ljungberg, Börje
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap.
    Lindahl, Olof
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    An improved resonance sensor system for detecting cancerous tissue in the prostate2005Inngår i: Proceedings of 13th Nordic Baltic Conference on Biomedical Engineering and Medical Physics / [ed] Ronnie Lundström, Britt Andersson, Helena Grip, Swedish Society for Medical Engineering and Medical Physics , 2005, s. 132-133Konferansepaper (Fagfellevurdert)
  • 82.
    Lindberg, Peter
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Andersson, Britt M
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Bergh, Anders
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk biovetenskap.
    Ljungberg, Börje
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap.
    Lindahl, Olof
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Hardness measurements on prostate with an improved resonance sensor system2006Inngår i: World Congress on Biomedical Engineering and Medical Physics, August 27 - September 1, 2006, Seoul, Korea, IFMBE , 2006Konferansepaper (Fagfellevurdert)
  • 83.
    Lindberg, Peter L
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Andersson, Britt M
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Bergh, Anders
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk biovetenskap, Patologi.
    Ljungberg, Börje
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Urologi och andrologi.
    Lindahl, Olof A
    Luleå tekniska Universitet.
    An image analysis method for prostate tissue classification: preliminary validation with resonance sensor data2009Inngår i: Journal of Medical Engineering & Technology, ISSN 0309-1902, E-ISSN 1464-522X, Vol. 33, nr 1, s. 18-24Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Resonance sensor systems have been shown to be able to distinguish between cancerous and normal prostate tissue, in vitro. The aim of this study was to improve the accuracy of the tissue determination, to simplify the tissue classification process with computerized morphometrical analysis, to decrease the risk of human errors, and to reduce the processing time. In this article we present our newly developed computerized classification method based on image analysis. In relation to earlier resonance sensor studies we increased the number of normal prostate tissue classes into stroma, epithelial tissue, lumen and stones. The linearity between the impression depth and tissue classes was calculated using multiple linear regression (R(2) = 0.68, n = 109, p < 0.001) and partial least squares (R(2) = 0.55, n = 109, p < 0.001). Thus it can be concluded that there existed a linear relationship between the impression depth and the tissue classes. The new image analysis method was easy to handle and decreased the classification time by 80%.

  • 84.
    Lindholm-Sethson, Britta
    et al.
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Kemi. Centrum för medicinsk teknik och fysik.
    Nyström, Josefina
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Kemi. Centrum för medicinsk teknik och fysik.
    Geladi, Paul
    Koeppe, Roger
    Nelson, Andrew
    Whitehouse, Conor
    Are biosensor arrays in one membrane possible? A combination of multifrequency impedance measurements and chemometrics2003Inngår i: Analytical and Bioanalytical Chemistry, Vol. 377, nr 3, s. 478-85Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A novel concept of a membrane-based micro-array biosensor is presented. The methodology is based on a single lipid membrane interrogated with electrochemical impedance techniques followed by multivariate data analysis. A single membrane is designed so that relaxation processes with a range of time constants can be probed at different potentials. A range of other approaches cited in the literature is reviewed.

  • 85.
    Lindkvist, Markus
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Granåsen, Gabriel
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Grönlund, Christer
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Coherent Derivation of Equations for Differential Spectroscopy and Spatially Resolved Spectroscopy: An undergraduate tutorial2013Inngår i: Spectroscopy Letters, ISSN 0038-7010, E-ISSN 1532-2289, Vol. 46, nr 4, s. 243-249Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Near-infrared spectroscopy (NIRS) is a spectroscopic method that is frequently used in health care and sports medicine to monitor oxygenation parameters in biological tissue. This tutorial provides a coherent derivation of equations for differential spectroscopy and spatially resolved spectroscopy, from basic theories to implementable equations. The basic theories are applicable to any kind of tissue oximeter but mainly focus on continuous-wave instruments. 

  • 86.
    Lindkvist, Markus
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Grönlund, Christer
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Absolute quantifications of oxy- and deoxyhemoglobin concentrations by combination of differentially resolved spectroscopy and spatially resolved spectroscopy2015Inngår i: Spectroscopy Letters, ISSN 0038-7010, E-ISSN 1532-2289, Vol. 48, nr 3, s. 170-172Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This letter proposes a theoretical framework to calculate absolute concentrations of oxy- and deoxyhemoglobin using continuous-wave near-infrared spectroscopy. While previous methods on this topic require assumptions on constant blood volume, the proposed method does not. Equations for the absolute concentrations were derived from a combination of the modified Beer-Lambert equation and the theory of diffusion of photons in turbid media. The method has an advantage over and is theoretically consistent with previous methods. It needs yet to be evaluated in an experimental study.

  • 87.
    Lindmark, Stina
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Medicin.
    Wiklund, Urban
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Klinisk fysiologi. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Bjerle, P
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Klinisk fysiologi.
    Eriksson, JW
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Medicin.
    Does the autonomic nervous system play a role in the development of insulin resistance?: a study on heart rate variability in first-degree relatives of type 2 diabetes patients and control subjects2003Inngår i: Diabetic Medicine, ISSN 0742-3071, E-ISSN 1464-5491, Vol. 20, nr 5, s. 399-405Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Aims To investigate dysregulation of the autonomic nervous system as a potential mechanism for early insulin resistance in the development of Type 2 diabetes.

    Methods Thirteen healthy individuals with first-degree relatives with Type 2 diabetes (R) were compared with 14 control subjects without family history of diabetes (C), matched for age, body mass index and sex. An oral glucose tolerance test and a hyperinsulinaemic euglycaemic clamp were performed. Analysis of heart rate variability during rest, controlled breathing, an orthostatic manoeuvre and a standardized physical stress (cold pressor test (CPT)), were used to evaluate the activity of the autonomic nervous system.

    Results Fasting blood glucose, HbA1c and serum insulin were similar in the R and C groups. The M-value, reflecting insulin sensitivity, did not differ significantly between the groups. Total spectral power and high-frequency power were lower in R during controlled breathing (P = 0.05 and P = 0.07, respectively), otherwise there were no significant differences between R and C in heart rate variability. However, low-frequency (LF)/high-frequency (HF) spectral power ratio during CPT, reflecting sympathetic/parasympathetic balance, was negatively associated with insulin sensitivity (r = −0.53, P = 0.006). When all subjects were divided into two groups by the mean M-value, the low M-value group displayed an overall higher LF/HF ratio (P = 0.04). HF power was lower in the low M-value group during controlled breathing and CPT (P = 0.01 and P = 0.03, respectively).

    Conclusion An altered balance of the parasympathetic and sympathetic nervous activity, mainly explained by an attenuated parasympathetic activity, might contribute to the development of insulin resistance and Type 2 diabetes.

  • 88.
    Manchester, Ian
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Andersson, Kennet
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Andersson, Nina
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Shiriaev, Anton S
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Eklund, Anders
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    A nonlinear obsever for on-line estimation of the cerebrospinal fluid outflow restistance.2008Inngår i: Automatica, ISSN 0005-1098, E-ISSN 1873-2836, Vol. 44, nr 5, s. 1426-1430Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Accurate estimates of the outflow resistance of the human cerebrospinal fluid system are important for the diagnosis of a medical condition known as hydrocephalus. In this paper we design a nonlinear observer which provides on-line estimates of the outflow resistance, to the best of our knowledge the first method to do so. The output of the observer is proven to globally converge to an unbiased estimate. Its performance is experimentally verified using the same apparatus used to perform actual patient diagnoses and a specially-designed physical model of the human cerebrospinal fluid system.

  • 89.
    Manchester, Ian R
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Andersson, Kennet
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper.
    Andersson, Nina
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Shiriaev, Anton S
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Eklund, Anders
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper.
    A nonlinear observer for on-line estimation of the cerebrospinal fluid outflow resistance2008Inngår i: Automatica, ISSN 0005-1098, E-ISSN 1873-2836, Vol. 44, s. 1426-1430Artikkel i tidsskrift (Fagfellevurdert)
  • 90.
    Mejtoft, Thomas
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Andersson, Britt M.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Pommer, Linda
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Karolina, Jonzén
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Kerstin, Ramser
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Wåhlin, Anders
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper. Umeå universitet, Medicinska fakulteten, Umeå centrum för funktionell hjärnavbildning (UFBI). Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Eklund, Anders
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper. Umeå universitet, Medicinska fakulteten, Institutionen för klinisk mikrobiologi, Biomedicinsk laboratorievetenskap. Umeå universitet, Medicinska fakulteten, Umeå centrum för funktionell hjärnavbildning (UFBI). Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Lindahl, Olof A
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF). Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper.
    Hallberg, Per
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF). Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Kan en branschspecifik innovationsmodell öka ”success rate” för medicintekniska innovationer?2019Konferansepaper (Annet vitenskapelig)
  • 91.
    Murayama, Yoshinobu
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF). College of Engineering, Nihon University, Koriyama, Fukushima, Japan; Luleå University, Luleå, Sweden.
    Yoshida, Kenta
    Takahashi, Harutaka
    Mizuno, Jinji
    Akaishi, Kazuyuki
    Inui, Hiroaki
    Softening of the Mouse Zona Pellucida during Oocyte Maturation2013Inngår i: 2013 35TH ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY (EMBC), IEEE , 2013, s. 6834-6837Konferansepaper (Fagfellevurdert)
    Abstract [en]

    A change in the elasticity and the resistance to dissolution of the mouse zona pellucida (ZP) was quantitatively evaluated at immature germinal vesicle (GV), mature metaphase II (MII) and fertilized pronuclear (PN) stages. Young's modulus of the ZP was measured using a micro tactile sensor (MTS), a highly sensitive resonator-based sensor for a micro scale elasticity measurement. 0.25% alpha-chymotrypsin was used for the ZP dissolution assay. The results of measuring the ZP elasticity and the dissolution time clearly showed that the ZP softened during oocyte maturation and the ZP hardened after fertilization. The results indicate that the amount of the zona softening can be a criterion to evaluate oocyte quality for the selection of top quality mature oocyte before in vitro fertilization (IVF) treatment.

  • 92. Nazaruk, Ewa
    et al.
    Bilewicz, Renata
    Lindblom, Göran
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Lindholm-Sethson, Britta
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Cubic phases in biosensing systems2008Inngår i: Analytical and Bioanalytical Chemistry, ISSN 1618-2642, E-ISSN 1618-2650, Vol. 391, nr 5, s. 1569-1578Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Incorporation of membrane proteins with retained activity in artificial membranes for use in membrane-based sensors has attracted scientists for decades. This review briefly summarises general concepts on relevant cubic phases with and without incorporated proteins and provides some insight into the development of biosensors where bicontinuous cubic phases are used for incorporation of an enzyme. Some new data on impedance characterisation of a supported cubic phase are also shown. An efficient membrane-based electrochemical biosensor requires that the analyte has free access to the immobilised membrane protein and that regeneration of the catalysing enzyme is fast. Long-term stability of the system is also necessary for the biosensor to find applications outside the research laboratory. These basic concepts are discussed in the review along with presentation of those biosensing systems based on cubic phases that are reported in the literature.

  • 93. Nilsson, Mats
    et al.
    Rasmark, Ulf
    Nordgren, Helena
    Hallberg, Per
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Skönevik, Johan
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Westman, Göran
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Allmänmedicin.
    Rolandsson, Olov
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Allmänmedicin.
    The physician at a distance: the use of videoconferencing in the treatment of patients with hypertension2009Inngår i: Journal of Telemedicine and Telecare, ISSN 1357-633X, E-ISSN 1758-1109, Vol. 15, nr 8, s. 397-403Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We evaluated the feasibility and quality of uncomplicated hypertension care based on telemedicine in a rural area of northern Sweden. The intervention subjects were 91 consecutive patients with primary hypertension. For comparison, 182 age- and sex-matched patients with hypertension were randomly selected from a similar health centre. The telemedicine equipment consisted of a video link between the physician and the patients, supported by a system for accessing medical data via the Internet. During a 21-month study period, telemedicine was used in 270 (91%) of the 297 consultations in the intervention group. All health personnel involved in the telemedicine treatment rated the method as feasible. Both systolic and diastolic blood pressure improved in the two groups during the study period. In the intervention group, a higher proportion had their blood pressure within treatment goals (systolic blood pressure <140 mmHg, diastolic blood pressure <90 mmHg) both at baseline and at follow-up than in the comparison group. An adjusted multivariate model (adjustment for sex, age, time between visits, change in number of drugs between first and last visit, blood pressure at first visit) showed that the intervention group had a higher probability (OR 2.7, 95% CI 1.4-5.2) of reaching the target blood pressure levels than the reference group. Treatment of hypertension by means of telemedicine was quite feasible and at least as effective as face-to-face consultations with a physician.

  • 94.
    Norén, Niklas
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Andersson, Britt
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Bergh, Anders
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk biovetenskap.
    Ljungberg, Börje
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap.
    Lindahl, Olof
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Spring-damper model for prostate tissue2005Inngår i: 13th Nordic-Baltic conference on biomedical engineering and medical physics, IFMBE , 2005, s. 281-282Konferansepaper (Fagfellevurdert)
  • 95.
    Nyberg, Morgan
    et al.
    Luleå University of Technology.
    Candefjord, Stefan
    Luleå University of Technology and Chalmers University of Technology.
    Jalkanen, Ville
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Ramser, Kerstin
    Luleå University of Technology.
    Lindahl, Olof A
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    A combined tactile and Raman probe for tissue characterization - design considerations2012Inngår i: Measurement science and technology, ISSN 0957-0233, E-ISSN 1361-6501, Vol. 23, nr 6, s. 065901-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Histopathology is the golden standard for cancer diagnosis and involves the characterization of tissue components. It is labour intensive and time consuming. We have earlier proposed a combined fibre-optic near-infrared Raman spectroscopy (NIR-RS) and tactile resonance method (TRM) probe for detecting positive surgical margins as a complement to interoperative histopathology. The aims of this study were to investigate the effects of attaching an RS probe inside a cylindrical TRM sensor and to investigate how laser-induced heating of the fibre-optic NIR-RS affected the temperature of the RS probe tip and an encasing TRM sensor. In addition, the possibility to perform fibre-optic NIR-RS in a well-lit environment was investigated. A small amount of rubber latex was preferable for attaching the thin RS probe inside the TRM sensor. The temperature rise of the TRM sensor due to a fibre-optic NIR-RS at 270 mW during 20 s was less than 2 °C. Fibre-optic NIR-RS was feasible in a dimmed bright environment using a small light shield and automatic subtraction of a pre-recorded contaminant spectrum. The results are promising for a combined probe for tissue characterization.

  • 96.
    Nyberg, Morgan
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF). Dept. of Engineering Sciences and Mathematics, Luleå University of Technology, Luleå, Sweden.
    Jalkanen, Ville
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Ramser, Kerstin
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF). Dept. of Engineering Sciences and Mathematics, Luleå University of Technology, Luleå, Sweden.
    Ljungberg, Börje
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Urologi och andrologi.
    Bergh, Anders
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk biovetenskap, Patologi.
    Lindahl, Olof A.
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF). Dept. of Engineering Sciences and Mathematics, Luleå University of Technology, Luleå, Sweden.
    Dual-modality probe intended for prostate cancer detection combining Raman spectroscopy and tactile resonance technology—discrimination of normal human prostate tissues ex vivo2015Inngår i: Journal of Medical Engineering & Technology, ISSN 0309-1902, E-ISSN 1464-522X, Vol. 39, nr 3, s. 198-207Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Prostate cancer is the most common cancer for men in the western world. For the first time, a dual-modality probe, combining Raman spectroscopy and tactile resonance technology, has been used for assessment of fresh human prostate tissue. The study investigates the potential of the dual-modality probe by testing its ability to differentiate prostate tissue types ex vivo. Measurements on four prostates show that the tactile resonance modality was able to discriminate soft epithelial tissue and stiff stroma (p<0.05). The Raman spectra exhibited a strong fluorescent background at the current experimental settings. However, stroma could be discerned from epithelia by integrating the value of the spectral background. Combining both parameters by a stepwise analysis resulted in 100% sensitivity and 91% specificity. Although no cancer tissue was analysed, the results are promising for further development of the instrument and method for discriminating prostate tissues and cancer.

  • 97.
    Nyberg, Morgan
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF). Institutionen för teknikvetenskap och matematik, Luleå tekniksa universitet.
    Jalkanen, Ville
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF). Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Ramser, Kerstin
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF). Institutionen för teknikvetenskap och matematik, Luleå tekniska universitet.
    Ljungberg, Börje
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Urologi och andrologi.
    Bergh, Anders
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk biovetenskap, Patologi.
    Lindahl, Olof A.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF). Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper. Institutionen för teknikvetenskap och matematik, Luleå tekniksa universitet.
    First study on freshly operated prostate tissue using a combination of Raman spectroscopy and tactile resonance sensor technology2014Inngår i: Medicinteknikdagarna 2014: Göteborg, 14-16 oktober, 2014, 2014, s. 26-26Konferansepaper (Fagfellevurdert)
  • 98.
    Nyberg, Morgan
    et al.
    Institutionen för systemteknik, Luleå tekniska universitet, Department of Computer Science and Electrical Engineering, Luleå University of Technology.
    Ramser, Kerstin
    Institutionen för systemteknik, Luleå tekniska universitet, Department of Computer Science and Electrical Engineering, Luleå University of Technology.
    Jalkanen, Ville
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Lindahl, Olof A.
    Institutionen för systemteknik, Luleå tekniska universitet, Department of Computer Science and Electrical Engineering, Luleå University of Technology.
    Kombinationsprob för prostatacancerdiagnostik - Ramanspektroskopi i dagsljus2010Inngår i: Medicinteknikdagarna 2010 / [ed] Ronnie Lundström, Umeå: Svensk förening för medicinsk teknik och fysik , 2010, s. 166-166Konferansepaper (Fagfellevurdert)
  • 99.
    Nyberg, Morgan
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Ramser, Kerstin
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Lindahl, Olof A.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF). Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Optical fibre probe NIR Raman measurements in ambient light and in combination with a tactile resonance sensor for possible cancer detection2013Inngår i: The Analyst, ISSN 0003-2654, E-ISSN 1364-5528, Vol. 138, nr 14, s. 4029-4034Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    First measurements on a combined instrument with a thin fibre optic Raman probe mounted inside a hollow tactile resonance sensor have been performed in ambient light on porcine tissue. The ambient fluorescent light was removed successfully from the spectra. The stiffness and the biomolecular composition of the tissue were analysed.

  • 100.
    Nyberg, Morgan
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF). Computer Science, Electrical and Space Engineering, Luleå University of Technology.
    Ville, Jalkanen
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Bergh, Anders
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk biovetenskap, Patologi.
    Ramser, Kerstin
    Computer Science, Electrical and Space Engineering, Luleå University of Technology.
    Lindahl, Olof A
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    First clinical study of prostate cancer detection with a dual sensor combining tactile resonance technique with fiber optical Raman spectroscopy2013Inngår i: 9th Workshop on FT-IR Spectroscopy in Microbiological and Medical Diagnostics, 2013Konferansepaper (Fagfellevurdert)
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