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  Subjects -> BIOLOGY (Total: 2939 journals)
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BIOLOGY (1422 journals)            First | 4 5 6 7 8 9 10 11 | Last

Istituto Lombardo - Accademia di Scienze e Lettere - Incontri di Studio     Open Access  
ITBM-RBM News     Full-text available via subscription   (Followers: 1)
IUBMB Life     Hybrid Journal   (Followers: 7)
IUFS Journal of Biology     Open Access  
Izvestiya Atmospheric and Oceanic Physics     Hybrid Journal   (Followers: 2)
Izvestiya, Physics of the Solid Earth     Hybrid Journal   (Followers: 2)
Japanese Journal of Applied Physics     Full-text available via subscription   (Followers: 3)
JCP : BioChemical Physics     Hybrid Journal   (Followers: 2)
JETP Letters     Hybrid Journal   (Followers: 2)
Journal of Bacteriology & Parasitology     Open Access   (Followers: 3)
Journal of Bioanalysis & Biomedicine     Open Access   (Followers: 1)
Journal of Bioequivalence & Bioavailability     Open Access  
Journal of Bioremediation & Biodegradation     Open Access   (Followers: 3)
Journal of Computer Science & Systems Biology     Open Access   (Followers: 2)
Journal of Proteomics & Bioinformatics     Open Access   (Followers: 8)
Journal of Advance Researches In Biological Sciences     Open Access   (Followers: 3)
Journal of Advances in Biology     Open Access   (Followers: 3)
Journal of Agricultural, Biological & Environmental Statistics     Hybrid Journal   (Followers: 10)
Journal of Amino Acids     Open Access   (Followers: 2)
Journal of AOAC International     Full-text available via subscription   (Followers: 9)
Journal of Applied Biobehavioral Research     Hybrid Journal  
Journal of Applied Bioinformatics & Computational Biology     Hybrid Journal   (Followers: 2)
Journal of Applied Biosciences     Open Access  
Journal of Applied Ichthyology     Hybrid Journal   (Followers: 6)
Journal of Applied Phycology     Hybrid Journal   (Followers: 10)
Journal of Applied Virology     Open Access   (Followers: 7)
Journal of Aquatic Sciences     Full-text available via subscription   (Followers: 3)
Journal of Arachnology     Full-text available via subscription  
Journal of Asia-Pacific Biodiversity     Open Access  
Journal of Astrobiology & Outreach     Open Access   (Followers: 1)
Journal of Avian Biology     Hybrid Journal   (Followers: 21)
Journal of Bacteriology     Full-text available via subscription   (Followers: 25)
Journal of Basic Microbiology     Hybrid Journal   (Followers: 3)
Journal of Bio-Science     Open Access   (Followers: 1)
Journal of Biobased Materials and Bioenergy     Full-text available via subscription  
Journal of Biodiversity & Endangered Species     Open Access  
Journal of Biodiversity Management & Forestry     Hybrid Journal   (Followers: 1)
Journal of Bioenergetics and Biomembranes     Hybrid Journal   (Followers: 1)
Journal of Biogeography     Hybrid Journal   (Followers: 30)
Journal of Bioinformatics and Computational Biology     Hybrid Journal   (Followers: 17)
Journal of Bioinformatics and Intelligent Control     Full-text available via subscription  
Journal of Biological and Information Sciences     Open Access   (Followers: 2)
Journal of Biological Dynamics     Open Access   (Followers: 1)
Journal of Biological Education     Hybrid Journal   (Followers: 1)
Journal of Biological Engineering     Open Access   (Followers: 4)
Journal of Biological Methods     Open Access  
Journal of Biological Physics     Hybrid Journal  
Journal of Biological Research - Thessaloniki     Open Access  
Journal of Biological Sciences     Open Access   (Followers: 4)
Journal of Biological Systems     Hybrid Journal   (Followers: 2)
Journal of Biology and Earth Sciences     Open Access   (Followers: 4)
Journal of Biology and Life Science     Open Access   (Followers: 2)
Journal of Biology, Agriculture and Healthcare     Open Access   (Followers: 5)
Journal of Biomarkers     Open Access   (Followers: 1)
Journal of Biomechanics     Hybrid Journal   (Followers: 30)
Journal of Biomedical Education     Open Access   (Followers: 2)
Journal of Biomedical Informatics     Partially Free   (Followers: 16)
Journal of Biomedical Materials Research Part A     Hybrid Journal   (Followers: 3)
Journal of Biomedical Materials Research Part B : Applied Biomaterials     Hybrid Journal   (Followers: 2)
Journal of Biomedical Nanotechnology     Full-text available via subscription   (Followers: 6)
Journal of Biomedical Physics and Engineering     Open Access  
Journal of Biomedical Science and Engineering     Open Access   (Followers: 2)
Journal of Biomolecular Screening     Hybrid Journal   (Followers: 7)
Journal of Bionic Engineering     Full-text available via subscription  
Journal of Biorheology     Hybrid Journal  
Journal of Bioscience and Bioengineering     Full-text available via subscription   (Followers: 34)
Journal of Biosciences and Medicines     Open Access  
Journal of Biosocial Science     Hybrid Journal   (Followers: 4)
Journal of Biotechnology and Biodiversity     Open Access   (Followers: 1)
Journal of Bryology     Hybrid Journal   (Followers: 6)
Journal of Cell and Plant Sciences     Open Access   (Followers: 5)
Journal of Cell Biology     Full-text available via subscription   (Followers: 34)
Journal of Cell Communication and Signaling     Hybrid Journal  
Journal of Cell Death     Open Access   (Followers: 1)
Journal of Cell Science     Full-text available via subscription   (Followers: 14)
Journal of Cellular Biochemistry     Hybrid Journal   (Followers: 5)
Journal of Cellular Physiology     Hybrid Journal   (Followers: 5)
Journal of Cerebral Blood Flow & Metabolism     Hybrid Journal   (Followers: 3)
Journal of Chromatography B     Hybrid Journal   (Followers: 36)
Journal of Clinical Bioinformatics     Open Access   (Followers: 6)
Journal of Clinical Toxicology     Open Access   (Followers: 2)
Journal of Communications Technology and Electronics     Hybrid Journal   (Followers: 1)
Journal of Contemporary Physics (Armenian Academy of Sciences)     Hybrid Journal   (Followers: 1)
Journal of Contradicting Results in Science     Open Access   (Followers: 2)
Journal of Crustacean Biology     Hybrid Journal   (Followers: 3)
Journal of Developmental Biology     Open Access   (Followers: 2)
Journal of Ecosystems     Open Access   (Followers: 4)
Journal of Education, Health and Sport     Open Access   (Followers: 5)
Journal of Electrical Bioimpedance     Full-text available via subscription   (Followers: 2)
Journal of Electromyography and Kinesiology     Hybrid Journal   (Followers: 5)
Journal of Environment and Ecology     Open Access   (Followers: 14)
Journal of Environmental Radioactivity     Hybrid Journal   (Followers: 3)
Journal of Environmental Science and Natural Resources     Open Access   (Followers: 2)
Journal of Ethnobiology     Full-text available via subscription   (Followers: 4)
Journal of Ethnobiology and Ethnomedicine     Open Access  
Journal of Ethology     Hybrid Journal   (Followers: 2)
Journal of Evolutionary Biology     Hybrid Journal   (Followers: 26)
Journal of Experimental and Clinical Anatomy     Open Access   (Followers: 2)
Journal of Experimental Marine Biology and Ecology     Hybrid Journal   (Followers: 38)
Journal of Fish Biology     Hybrid Journal   (Followers: 33)

  First | 4 5 6 7 8 9 10 11 | Last

Journal Cover Medical Engineering & Physics
  [SJR: 0.871]   [H-I: 64]   [9 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 1350-4533
   Published by Elsevier Homepage  [2805 journals]
  • A method to adapt thoracic impedance based on chest geometry and
           composition to assess congestion in heart failure patients
    • Abstract: Publication date: Available online 14 April 2016
      Source:Medical Engineering & Physics
      Author(s): Illapha Cuba-Gyllensten, Paloma Gastelurrutia, Alberto G. Bonomi, Jarno Riistama, Antoni Bayes-Genis, Ronald M. Aarts
      Multi-frequency trans-thoracic bioimpedance (TTI) could be used to track fluid changes and congestion of the lungs, however, patient specific characteristics may impact the measurements. We investigated the effects of thoracic geometry and composition on measurements of TTI and developed an equation to calculate a personalized fluid index. Simulations of TTI measurements for varying levels of chest circumference, fat and muscle proportion were used to derive parameters for a model predicting expected values of TTI. This model was then adapted to measurements from a control group of 36 healthy volunteers to predict TTI and lung fluids (fluid index). Twenty heart failure (HF) patients treated for acute HF were then used to compare the changes in the personalized fluid index to symptoms of HF and predicted TTI to measurements at hospital discharge. All the derived body characteristics affected the TTI measurements in healthy volunteers and together the model predicted the measured TTI with 8.9% mean absolute error. In HF patients the estimated TTI correlated well with the discharged TTI ( r = 0.73 , p <0.001) and the personalized fluid index followed changes in symptom levels during treatment. However, 37% ( n = 7 ) of the patients were discharged well below the model expected value. Accounting for chest geometry and composition might help in interpreting TTI measurements.


      PubDate: 2016-04-26T16:13:35Z
       
  • Comparison of three methods for identifying the heelstrike transient
           during walking gait
    • Abstract: Publication date: Available online 21 April 2016
      Source:Medical Engineering & Physics
      Author(s): J. Troy Blackburn, Brian G. Pietrosimone, Matt S. Harkey, Brittney A. Luc, Derek N. Pamukoff
      Impulsive, or high rate, loading contributes to cartilage degradation and is commonly identified via the heelstrike transient (HST) in the vertical ground reaction force (vGRF) during gait. Investigation of the HST may improve our understanding of knee osteoarthritis mechanical pathogenesis. However, the most appropriate method for objectively identifying the HST is unclear. Twenty-eight healthy subjects walked at a self-selected pace while vGRF data were captured. The efficacies of three HST identification methods (Radin, Hunt, and Modified Hunt) were evaluated using vGRF data lowpass filtered at three frequencies (raw/unfiltered, 75Hz, and 50Hz). Both the HST identification method and lowpass filter frequency influenced whether a HST was identified and whether a subject was classified as an “impulsive loader” (i.e. HST identified in 3 of 5 trials). The methods identified different phenomena in the vGRF, with the Radin and Modified Hunt methods identifying the HST 11-16ms following ground contact and the Hunt method identifying the HST 83–122ms following ground contact. Lowpass filtering the vGRF at 75Hz and implementing the Radin method was the most effective approach for identifying the HST. Future longitudinal observations are necessary to determine if specific HST criteria are indicative of knee osteoarthritis development and progression.


      PubDate: 2016-04-26T16:13:35Z
       
  • Segmented beat modulation method for electrocardiogram estimation from
           noisy recordings
    • Abstract: Publication date: Available online 21 April 2016
      Source:Medical Engineering & Physics
      Author(s): Angela Agostinelli, Agnese Sbrollini, Corrado Giuliani, Sandro Fioretti, Francesco Di Nardo, Laura Burattini
      Clinical utility of an electrocardiogram (ECG) affected by too high levels of noise such as baseline wanders, electrode motion artifacts, muscular artifacts and power-line interference may be jeopardized if not opportunely processed. Template-based techniques have been proposed for ECG estimation from noisy recordings, but usually they do not reproduce physiological ECG variability, which, however, provides clinically useful information on the patient's health. Thus, this study proposes the Segmented-Beat Modulation Method (SBMM) as a new template-based filtering procedure able to reproduce ECG variability, and assesses SBMM robustness to the aforementioned noises in comparison to a standard template method (STM). SBMM performs a unique ECG segmentation into QRS segment and TUP segment, and successively modulates/demodulates (by stretching or compressing) the former segments in order to adaptively adjust each estimated beat to its original morphology and duration. Consequently, SBMM estimates ECG with significantly lower estimation errors than STM when applied to recordings affected by various levels of the considered noises (SBMM: 176–232µV and 79–499µV; STM: 215–496µV and 93–1056µV, for QRS and TUP segments, respectively). Thus, SBMM is able to reproduce ECG variability and is more robust to noise than STM.


      PubDate: 2016-04-26T16:13:35Z
       
  • Bioactive glass surface for fiber reinforced composite implants via
           surface etching by Excimer laser
    • Abstract: Publication date: Available online 25 April 2016
      Source:Medical Engineering & Physics
      Author(s): Julia Kulkova, Niko Moritz, Hannu Huhtinen, Riina Mattila, Ivan Donati, Eleonora Marsich, Sergio Paoletti, Pekka K Vallittu
      Biostable fiber-reinforced composites (FRC) prepared from bisphenol-A-glycidyldimethacrylate (BisGMA)-based thermosets reinforced with E-glass fibers are promising alternatives to metallic implants due to the excellent fatigue resistance and the mechanical properties matching those of bone. Bioactive glass (BG) granules can be incorporated within the polymer matrix to improve the osteointegration of the FRC implants. However, the creation of a viable surface layer using BG granules is technically challenging. In this study, we investigated the potential of Excimer laser ablation to achieve the selective removal of the matrix to expose the surface of BG granules. A UV–vis spectroscopic study was carried out to investigate the differences in the penetration of light in the thermoset matrix and BG. Thereafter, optimal Excimer laser ablation parameters were established. The formation of a calcium phosphate (CaP) layer on the surface of the laser-ablated specimens was verified in simulated body fluid (SBF). In addition, the proliferation of MG63 cells on the surfaces of the laser-ablated specimens was investigated. For the laser-ablated specimens, the pattern of proliferation of MG63 cells was comparable to that in the positive control group (Ti6Al4V). We concluded that Excimer laser ablation has potential for the creation of a bioactive surface on FRC-implants.
      Graphical abstract image

      PubDate: 2016-04-26T16:13:35Z
       
  • A robust approach for ECG-based analysis of cardiopulmonary coupling
    • Abstract: Publication date: Available online 23 April 2016
      Source:Medical Engineering & Physics
      Author(s): Jiewen Zheng, Weidong Wang, Zhengbo Zhang, Dalei Wu, Hao Wu, Chung-kang Peng
      Deriving respiratory signal from a surface electrocardiogram (ECG) measurement has advantage of simultaneously monitoring of cardiac and respiratory activities. ECG-based cardiopulmonary coupling (CPC) analysis estimated by heart period variability and ECG-derived respiration (EDR) shows promising applications in medical field. The aim of this paper is to provide a quantitative analysis of the ECG-based CPC, and further improve its performance. Two conventional strategies were tested to obtain EDR signal: R-S wave amplitude and area of the QRS complex. An adaptive filter was utilized to extract the common component of inter-beat interval (RRI) and EDR, generating enhanced versions of EDR signal. CPC is assessed through probing the nonlinear phase interactions between RRI series and respiratory signal. Respiratory oscillations presented in both RRI series and respiratory signals were extracted by ensemble empirical mode decomposition for coupling analysis via phase synchronization index. The results demonstrated that CPC estimated from conventional EDR series exhibits constant and proportional biases, while that estimated from enhanced EDR series is more reliable. Adaptive filtering can improve the accuracy of the ECG-based CPC estimation significantly and achieve robust CPC analysis. The improved ECG-based CPC estimation may provide additional prognostic information for both sleep medicine and autonomic function analysis.


      PubDate: 2016-04-26T16:13:35Z
       
  • Shoulder pain and time dependent structure in wheelchair propulsion
           variability
    • Abstract: Publication date: Available online 25 April 2016
      Source:Medical Engineering & Physics
      Author(s): Chandrasekaran Jayaraman, Yaejin Moon, Jacob J. Sosnoff
      Manual wheelchair propulsion places considerable repetitive mechanical strain on the upper limbs leading to shoulder injury and pain. While recent research indicates that the amount of variability in wheelchair propulsion and shoulder pain may be related. There has been minimal inquiry into the fluctuation over time (i.e. time-dependent structure) in wheelchair propulsion variability. Consequently the purpose of this investigation was to examine if the time-dependent structure in the wheelchair propulsion parameters are related to shoulder pain. 27 experienced wheelchair users manually propelled their own wheelchair fitted with a SMARTWheel on a roller at 1.1m/s for 3min. Time-dependent structure of cycle-to-cycle fluctuations in contact angle and inter push time interval was quantified using sample entropy (SampEn) and compared between the groups with/without shoulder pain using non-parametric statistics. Overall findings were, (1) variability observed in contact angle fluctuations during manual wheelchair propulsion is structured (Z=3.15;p<0.05), (2) individuals with shoulder pain exhibited higher SampEn magnitude for contact angle during wheelchair propulsion than those without pain (χ2(1)=6.12;p<0.05); and (3) SampEn of contact angle correlated significantly with self-reported shoulder pain (rs (WUSPI) =0.41;rs (VAS)=0.56;p<0.05). It was concluded that the time-dependent structure in wheelchair propulsion may provide novel information for tracking and monitoring shoulder pain.


      PubDate: 2016-04-26T16:13:35Z
       
  • Assessment of accuracy and precision of 3D reconstruction of
           unicompartmental knee arthroplasty in upright position using biplanar
           radiography
    • Abstract: Publication date: Available online 23 April 2016
      Source:Medical Engineering & Physics
      Author(s): Tsung-Yuan Tsai, Dimitris Dimitriou, Ali Hosseini, Ming Han Lincoln Liow, Martin Torriani, Guoan Li, Young-Min Kwon
      This study aimed to evaluate the precision and accuracy of 3D reconstruction of UKA component position, contact location and lower limb alignment in standing position using biplanar radiograph. Two human specimens with 4 medial UKAs were implanted with beads for radiostereometric analysis (RSA). The specimens were frozen in standing position and CT-scanned to obtain relative positions between the beads, bones and UKA components. The specimens were then imaged using biplanar radiograph (EOS). The positions of the femur, tibia, UKA components and UKA contact locations were obtained using RSA- and EOS-based techniques. Intraclass correlation coefficient (ICC) was calculated for inter-observer reliability of the EOS technique. The average (standard deviation) of the differences between two techniques in translations and rotations were less than 0.18 (0.29) mm and 0.39° (0.66°) for UKA components. The root-mean-square-errors (RMSE) of contact location along the anterior/posterior and medial/lateral directions were 0.84mm and 0.30mm. The RMSEs of the knee rotations were less than 1.70°. The ICCs for the EOS-based segmental orientations between two raters were larger than 0.98. The results suggest the EOS-based 3D reconstruction technique can precisely determine component position, contact location and lower limb alignment for UKA patients in weight-bearing standing position.


      PubDate: 2016-04-26T16:13:35Z
       
  • Corrigendum to ‘Intraprosthetic screw fixation increases primary
           fixation stability in periprosthetic fractures of the femur—A
           biomechanical study.’ [Med. Eng. Phys. 36 (2014) 239–243]
    • Abstract: Publication date: Available online 23 April 2016
      Source:Medical Engineering & Physics
      Author(s): Stephan Brand, Johannes Klotz, Thomas Hassel, Maximilian Petri, Max Ettinger, Friedrich-Wilhelm Bach, Christian Krettek, Thomas Gösling



      PubDate: 2016-04-26T16:13:35Z
       
  • Evaluating the usability of a smartphone virtual seating coach application
           for powered wheelchair users
    • Abstract: Publication date: Available online 11 April 2016
      Source:Medical Engineering & Physics
      Author(s): Yu-Kuang Wu, Hsin-Yi Liu, Annmarie Kelleher, Jonathan Pearlman, Rory A. Cooper
      The aim of the smartphone virtual seating coach (SVSC) was to provide a personalized reminder/warning system to encourage powered wheelchair users to use their powered seating functions (PSFs) as clinically recommended. This study evaluated the usability of the SVSC system by gathering feedback from five powered wheelchair users and five rehabilitation professionals through questionnaires and interviews. The results indicated that clear and understandable instructions to adjust the PSFs are the most important requirement for SVSC application. The instructions must be intuitive, could benefit from animations or indications of PSFs control buttons so powered wheelchair users can adjust their PSFs immediately and appropriately.


      PubDate: 2016-04-26T16:13:35Z
       
  • Mechanical testing and modelling of the Universal 2 implant
    • Abstract: Publication date: Available online 12 April 2016
      Source:Medical Engineering & Physics
      Author(s): M.K. Gislason, E. Foster, D. Main, G. Fusiek, P. Niewczas, M. Bransby-Zachary, D.H. Nash
      Understanding the load mechanics of orthopaedic implants is important to be able to predict their behaviour in-vivo. Much research, both mechanical and clinical, has been carried out on hip and knee implants, but less has been written about the mechanics of wrist implants. In this paper, the load mechanics of the Universal 2 wrist implant have been measured using two types of measuring techniques, strain gauges and Fibre Bragg Grating measurements to measure strains. The results were compared to a finite element model of the implant. The results showed that the computational results were in good agreement with the experimental results. Better understanding of the load mechanics of wrist implants, using models and experimental results can catalyse the development of future generation implants.


      PubDate: 2016-04-26T16:13:35Z
       
  • Accuracy and repeatability of quantitative fluoroscopy for the measurement
           of sagittal plane translation and finite centre of rotation in the lumbar
           spine
    • Abstract: Publication date: Available online 26 April 2016
      Source:Medical Engineering & Physics
      Author(s): Alexander Breen, Alan Breen
      Quantitative fluoroscopy (QF) was developed to measure intervertebral mechanics in vivo and has been found to have high repeatability and accuracy for the measurement of intervertebral rotations. However, sagittal plane translation and finite centre of rotation (FCR) are potential measures of stability but have not yet been fully validated for current QF. This study investigated the repeatability and accuracy of QF for measuring these variables. Repeatability was assessed from L2-S1 in 20 human volunteers. Accuracy was investigated using 10 consecutive measurements from each of two pairs of linked and instrumented dry human vertebrae as reference; one which tilted without translation and one which translated without tilt. The results found intra- and inter-observer repeatability for translation to be 1.1mm or less (SEM) with fair to substantial reliability (ICC 0.533–0.998). Intra-observer repeatability of FCR location for inter-vertebral rotations of 5° and above ranged from 1.5mm to 1.8mm (SEM) with moderate to substantial reliability (ICC 0.626–0.988). Inter-observer repeatability for FCR ranged from 1.2mm to 5.7mm, also with moderate to substantial reliability (ICC 0.621–0.878). Reliability was substantial (ICC>0.81) for 10/16 measures for translation and 5/8 for FCR location. Accuracy for translation was 0.1mm (fixed centre) and 2.2mm (moveable centre), with an FCR error of 0.3mm(x) and 0.4mm(y) (fixed centre). This technology was found to have a high level of accuracy and with a few exceptions, moderate to substantial repeatability for the measurement of translation and FCR from fluoroscopic motion sequences.


      PubDate: 2016-04-26T16:13:35Z
       
  • Editorial Board
    • Abstract: Publication date: May 2016
      Source:Medical Engineering & Physics, Volume 38, Issue 5




      PubDate: 2016-04-26T16:13:35Z
       
  • Physics-driven impeller designs for a novel intravascular blood pump for
           patients with congenital heart disease
    • Abstract: Publication date: Available online 26 April 2016
      Source:Medical Engineering & Physics
      Author(s): Steven G. Chopski, Carson S. Fox, Kelli L. McKenna, Michelle L. Riddle, Dhyaa H. Kafagy, Randy M. Stevens, Amy L. Throckmorton
      Mechanical circulatory support offers an alternative therapeutic treatment for patients with dysfunctional single ventricle physiology. An intravascular axial flow pump is being developed as a cavopulmonary assist device for these patients. This study details the development of a new rotating impeller geometry. We examined the performance of 8 impeller geometries with blade stagger or twist angles varying from 100° to 800° using computational methods. A refined range of blade twist angles between 300° and 400° was then identified, and 4 additional geometries were evaluated. Generally, the impeller designs produced 4–26mmHg for flow rates of 1–4L/min for 6000–8000 RPM. A data regression analysis was completed and found the impeller with 400° of blade twist to be the superior performer. A hydraulic test was conducted on a prototype of the 400° impeller, which generated measurable pressure rises of 7–28mmHg for flow rates of 1–4L/min at 6000–8000 RPM. The findings of the numerical model and experiment were in reasonable agreement within approximately 20%. These results support the continued development of an axial-flow, mechanical cavopulmonary assist device as a new clinical therapeutic option for Fontan patients.


      PubDate: 2016-04-26T16:13:35Z
       
  • A pressure and shear sensor system for stress measurement at lower limb
           residuum/socket interface
    • Abstract: Publication date: Available online 23 April 2016
      Source:Medical Engineering & Physics
      Author(s): P. Laszczak, M. McGrath, J. Tang, J. Gao, L. Jiang, D.L. Bader, D. Moser, S. Zahedi
      A sensor system for measurement of pressure and shear at the lower limb residuum/socket interface is described. The system comprises of a flexible sensor unit and a data acquisition unit with wireless data transmission capability. Static and dynamic performance of the sensor system was characterised using a mechanical test machine. The static calibration results suggest that the developed sensor system presents high linearity (linearity error ≤ 3.8%) and resolution (0.9 kPa for pressure and 0.2 kPa for shear). Dynamic characterisation of the sensor system shows hysteresis error of approximately 15% for pressure and 8% for shear. Subsequently, a pilot amputee walking test was conducted. Three sensors were placed at the residuum/socket interface of a knee disarticulation amputee and simultaneous measurements were obtained during pilot amputee walking test. The pressure and shear peak values as well as their temporal profiles are presented and discussed. In particular, peak pressure and shear of approximately 58 kPa and 27 kPa, respectively, were recorded. Their temporal profiles also provide dynamic coupling information at this critical residuum/socket interface. These preliminary amputee test results suggest strong potential of the developed sensor system for exploitation as an assistive technology to facilitate socket design, socket fit and effective monitoring of lower limb residuum health.


      PubDate: 2016-04-26T16:13:35Z
       
  • Bilateral robots for upper-limb stroke rehabilitation: State of the art
           and future prospects
    • Abstract: Publication date: Available online 24 April 2016
      Source:Medical Engineering & Physics
      Author(s): Bo Sheng, Yanxin Zhang, Wei Meng, Chao Deng, Shengquan Xie
      Robot-assisted bilateral upper-limb training grows abundantly for stroke rehabilitation in recent years and an increasing number of devices and robots have been developed. This paper aims to provide a systematic overview and evaluation of existing bilateral upper-limb rehabilitation devices and robots based on their mechanisms and clinical-outcomes. Most of the articles studied here were searched from nine online databases and the China National Knowledge Infrastructure (CNKI) from year 1993 to 2015. Devices and robots were categorized as end-effectors, exoskeletons and industrial robots. Totally ten end-effectors, one exoskeleton and one industrial robot were evaluated in terms of their mechanical characteristics, degrees of freedom (DOF), supported control modes, clinical applicability and outcomes. Preliminary clinical results of these studies showed that all participants could gain certain improvements in terms of range of motion, strength or physical function after training. Only four studies supported that bilateral training was better than unilateral training. However, most of clinical results cannot definitely verify the effectiveness of mechanisms and clinical protocols used in robotic therapies. To explore the actual value of these robots and devices, further research on ingenious mechanisms, dose-matched clinical protocols and universal evaluation criteria should be conducted in the future.


      PubDate: 2016-04-26T16:13:35Z
       
  • The carotid artery as an alternative site for dynamic autoregulation
           measurement: an inter-observer reproducibility study
    • Abstract: Publication date: Available online 25 April 2016
      Source:Medical Engineering & Physics
      Author(s): R.C. Nogueira, N.P. Saeed, E. Bor-Seng-Shu, M.J. Teixeira, T.G. Robinson, R.B. Panerai
      The internal carotid artery (ICA) has been proposed as an alternative site to the middle cerebral artery (MCA) to measure dynamic cerebral autoregulation (dCA) using transcranial Doppler ultrasound (TCD). Our aim was to test the inter-operator reproducibility of dCA assessment in the ICA and the effect of interaction amongst different variables (artery source × operator × intra-subject variability). Two operators measured blood flow velocity using TCD at the ICA and MCA simultaneously on each side in 12 healthy volunteers. The autoregulation index (ARI) was estimated by transfer function analysis. A two-way repeated measurements ANOVA with post-hoc Tukey tested the difference between ARI by different operators and interaction effects were analysed based on the generalized linear model. In this healthy population, no significant differences between operator and no interaction effects were identified amongst the different variables. This study reinforced the validity of using the ICA as an alternative site for the assessment of dCA. Further work is needed to confirm and extend our findings, particularly to disease populations.


      PubDate: 2016-04-26T16:13:35Z
       
  • Red blood cell ghosts as promising drug carriers to target wound
           infections
    • Abstract: Publication date: Available online 6 April 2016
      Source:Medical Engineering & Physics
      Author(s): Kulzhan Berikkhanova, Rustam Omarbaev, Alexandr Gulyayev, Zarina Shulgau, Dilbar Ibrasheva, Gulsim Adilgozhina, Shynggys Sergazy, Zhaxybay Zhumadilov, Sholpan Askarova
      Autologous red blood cell ghosts (RBC ghosts) can carry cytokines to the sites of inflammation. The targeting moiety of the RBC ghosts is associated with the nature of purulent inflammation, where the erythrocytes are phagocyted and encapsulated drugs are released. In the present study we have investigated the healing potential of RBC ghosts loaded with cytokine IL-1β and antibiotic. Additionally, the pharmacokinetic properties of RBC ghosts loaded with IL-1β were studied. 35 Male Wistar rats (250–300g) were used in the pharmacokinetic study and in a wound infection model where a suspension of Staphylococcus aureus was placed into a surgical cut of the skin and subcutaneous tissue in the femoral region. In order to monitor progression of the wound repair processes, wound swabs or aspiration biopsies were taken for analyses on the 1st–6th days. Wound repair dynamics assessment was based on suppression of S. aureus growth, signs of pain, time of disappearance of pus and infiltration around the wound. Visual observations, as well as microbiological and cytological analysis of wound exudates demonstrated a significant acceleration of healing processes in a group of animals treated with a local injection of IL-1β and ceftriaxone encapsulated into RBC ghosts when compared to the animals treated either with a local or IM injection of free drugs. For the pharmacokinetic study, single IV injections of either free or encapsulated IL-1β were made and the concentration of IL-1β in serum samples and tissue homogenates were determined. Encapsulation in RBC ghosts improved pharmacokinetic profiles of IL-1β by increasing the half-life, reducing its clearance, and increasing the deposition of the drug in the liver, spleen and lungs. These data suggest that RBC ghosts are effective drug carriers for targeted delivery of cytokines to the sites of inflammation, and have a potential for improving the treatment outcomes of purulent diseases.


      PubDate: 2016-04-09T05:35:45Z
       
  • Towards the generation of a parametric foot model using principal
           component analysis: A pilot study
    • Abstract: Publication date: Available online 7 April 2016
      Source:Medical Engineering & Physics
      Author(s): Alessandra Scarton, Zimi Sawacha, Claudio Cobelli, Xinshan Li
      There have been many recent developments in patient-specific models with their potential to provide more information on the human pathophysiology and the increase in computational power. However they are not yet successfully applied in a clinical setting. One of the main challenges is the time required for mesh creation, which is difficult to automate. The development of parametric models by means of the Principle Component Analysis (PCA) represents an appealing solution. In this study PCA has been applied to the feet of a small cohort of diabetic and healthy subjects, in order to evaluate the possibility of developing parametric foot models, and to use them to identify variations and similarities between the two populations. Both the skin and the first metatarsal bones have been examined. Besides the reduced sample of subjects considered in the analysis, results demonstrated that the method adopted herein constitutes a first step towards the realization of a parametric foot models for biomechanical analysis. Furthermore the study showed that the methodology can successfully describe features in the foot, and evaluate differences in the shape of healthy and diabetic subjects.


      PubDate: 2016-04-09T05:35:45Z
       
  • Staying in dynamic balance on a prosthetic limb: A leg to stand on?
    • Abstract: Publication date: Available online 1 April 2016
      Source:Medical Engineering & Physics
      Author(s): Carolin Curtze, At L. Hof, Klaas Postema, Bert Otten
      With the loss of a lower limb, amputees lack the active muscle empowered control of the ankle that is important for balance control. We examined single-leg stance on prosthesis vs. sound limb balancing on narrow ridges in transtibial amputees. When balancing on the prosthetic limb, the lateral displacement of the center of pressure was reduced and was compensated by an increase in counter-rotation. We show that single-leg stance on a prosthetic limb can be compared to balancing on a narrow ridge. Standing on a prosthetic limb involves the same balance mechanisms as balancing on narrow ridges of 40-mm to 20-mm width. Yet, the ability to balance on a narrow ridge with the sound limb was only a weak predictor for an amputee's ability to stand on the prosthetic limb. Balancing in single-leg stance on a prosthetic limb is not a common activity. The ability to compensate with the sound limb may therefore be functionally more important than the ability to stay in dynamic balance on the prosthetic limb.


      PubDate: 2016-04-05T05:08:34Z
       
  • The contact mechanics and occurrence of edge loading in modular
           metal-on-polyethylene total hip replacement during daily activities
    • Abstract: Publication date: Available online 4 April 2016
      Source:Medical Engineering & Physics
      Author(s): Xijin Hua, Junyan Li, Zhongmin Jin, John Fisher
      The occurrence of edge loading in hip joint replacement has been associated with many factors such as prosthetic design, component malposition and activities of daily living. The present study aimed to quantify the occurrence of edge loading/contact at the articulating surface and to evaluate the effect of cup angles and edge loading on the contact mechanics of a modular metal-on-polyethylene (MoP) total hip replacement (THR) during different daily activities. A three-dimensional finite element model was developed based on a modular MoP bearing system. Different cup inclination and anteversion angles were modelled and six daily activities were considered. The results showed that edge loading was predicted during normal walking, ascending and descending stairs activities under steep cup inclination conditions (≥55°) while no edge loading was observed during standing up, sitting down and knee bending activities. The duration of edge loading increased with increased cup inclination angles and was affected by the cup anteversion angles. Edge loading caused elevated contact pressure at the articulating surface and substantially increased equivalent plastic strain of the polyethylene liner. The present study suggested that correct positioning the component to avoid edge loading that may occur during daily activities is important for MoP THR in clinical practice.


      PubDate: 2016-04-05T05:08:34Z
       
  • Patient-specific modelling of abdominal aortic aneurysms: The influence of
           wall thickness on predicted clinical outcomes
    • Abstract: Publication date: Available online 4 April 2016
      Source:Medical Engineering & Physics
      Author(s): Noel Conlisk, Arjan J. Geers, Olivia M.B. McBride, David E. Newby, Peter R. Hoskins
      Rupture of abdominal aortic aneurysms (AAAs) is linked to aneurysm morphology. This study investigates the influence of patient-specific (PS) AAA wall thickness on predicted clinical outcomes. Eight patients under surveillance for AAAs were selected from the MA3RS clinical trial based on the complete absence of intraluminal thrombus. Two finite element (FE) models per patient were constructed; the first incorporated variable wall thickness from CT (PS_wall), and the second employed a 1.9mm uniform wall (Uni_wall). Mean PS wall thickness across all patients was 1.77±0.42mm. Peak wall stress (PWS) for PS_wall and Uni_wall models was 0.6761±0.3406N/mm2 and 0.4905±0.0850N/mm2, respectively. In 4 out of 8 patients the Uni_wall underestimated stress by as much as 55%; in the remaining cases it overestimated stress by up to 40%. Rupture risk more than doubled in 3 out of 8 patients when PS_wall was considered. Wall thickness influenced the location and magnitude of PWS as well as its correlation with curvature. Furthermore, the volume of the AAA under elevated stress increased significantly in AAAs with higher rupture risk indices. This highlights the sensitivity of standard rupture risk markers to the specific wall thickness strategy employed.


      PubDate: 2016-04-05T05:08:34Z
       
  • An external portable device for adaptive deep brain stimulation (aDBS)
           clinical research in advanced Parkinson's Disease
    • Abstract: Publication date: Available online 27 March 2016
      Source:Medical Engineering & Physics
      Author(s): Mattia Arlotti, Lorenzo Rossi, Manuela Rosa, Sara Marceglia, Alberto Priori
      Compared to conventional deep brain stimulation (DBS) for patients with Parkinson's Disease (PD), the newer approach of adaptive DBS (aDBS), regulating stimulation on the basis of the patient's clinical state, promises to achieve better clinical outcomes, avoid adverse-effects and save time for tuning parameters. A remaining challenge before aDBS comes into practical use is to prove its feasibility and its effectiveness in larger groups of patients and in more ecological conditions. We developed an external portable aDBS system prototype designed for clinical testing in freely-moving PD patients with externalized DBS electrodes. From a single-channel bipolar artifact-free recording, it analyses local field potentials (LFPs), during ongoing DBS for tuning stimulation parameters, independent from the specific feedback algorithm implemented. We validated the aDBS system in vitro, by testing both its sensing and closed-loop stimulation capabilities, and then tested it in vivo, focusing on the sensing capabilities. By applying the aDBS system prototype in a patient with PD, we provided evidence that it can track levodopa and DBS-induced LFP spectral power changes among different patient's clinical states. Our system, intended for testing LFP-based feedback strategies for aDBS, should help understanding how and whether aDBS therapy works in PD and indicating future technical and clinical advances.


      PubDate: 2016-03-28T03:44:03Z
       
  • Radiofrequency ablation with a vibrating catheter: A new method for
           electrode cooling
    • Abstract: Publication date: Available online 21 March 2016
      Source:Medical Engineering & Physics
      Author(s): Kaihong Yu, Tetsui Yamashita, Shigeaki Shingyochi, Kazuo Matsumoto, Makoto Ohta
      A new electrode cooling system using a vibrating catheter is described for conditions of low blood flow when saline irrigation cannot be used. Vibrations of the catheter are hypothesized to disturb blood flow around the electrode, leading to increased convective cooling of the electrode. The aim of this study is to confirm the cooling effect of vibration and investigate the associated mechanisms. As methods, an in vitro system with polyvinyl alcohol-hydrogel (PVA-H) as ablated tissue and saline flow in an open channel was used to measure changes in electrode and tissue temperatures under vibration of 0–63Hz and flow velocity of 0–0.1m/s. Flow around the catheter was observed using particle image velocimetry (PIV). Results show that under conditions of no flow, electrode temperatures decreased with increasing vibration frequency, and in the absence of vibrations, electrode temperatures decreased with increasing flow velocity. In the presence of vibrations, electrode temperatures decreased under conditions of low flow velocity, but not under those of high flow velocity. PIV analyses showed disturbed flow around the vibrating catheter, and flow velocity around the catheter increased with higher-frequency vibrations. In conclusion, catheter vibration facilitated electrode cooling by increasing flow around the catheter, and cooling was proportional to vibration frequency.


      PubDate: 2016-03-24T03:09:52Z
       
  • Product limit estimation for capturing of pressure distribution dynamics
    • Abstract: Publication date: Available online 22 March 2016
      Source:Medical Engineering & Physics
      Author(s): Michael Wininger, Barbara A. Crane
      Measurement of contact pressures at the wheelchair-seating interface is a critically important approach for laboratory research and clinical application in monitoring risk for pressure ulceration. As yet, measures obtained from pressure mapping are static in nature: there is no accounting for changes in pressure distribution over time, despite the well-known interaction between time and pressure in risk estimation. Here, we introduce the first dynamic analysis for distribution of pressure data, based on the Kaplan–Meier (KM) Product Limit Estimator (PLE) a ubiquitous tool encountered in clinical trials and survival analysis. In this approach, the pressure array-over-time data set is sub-sampled two frames at a time (random pairing), and their similarity of pressure distribution is quantified via a correlation coefficient. A large number (here: 100) of these frame pairs is then sorted into descending order of correlation value, and visualized as a KM curve; we build confidence limits via a bootstrap computed over 1000 replications. PLEs and the KM have robust statistical support and extensive development: the opportunities for extended application are substantial. We propose that the KM-PLE in particular, and dynamic analysis in general, may provide key leverage on future development of seating technology, and valuable new insight into extant datasets.


      PubDate: 2016-03-24T03:09:52Z
       
  • Influence of fibrous encapsulation on electro-chemical properties of TiN
           electrodes
    • Abstract: Publication date: Available online 17 March 2016
      Source:Medical Engineering & Physics
      Author(s): Suzan Meijs, Morten Fjorback, Carina Jensen, Søren Sørensen, Kristian Rechendorff, Nico J.M. Rijkhoff
      The aim of this study was to investigate how the electrochemical properties of porous titanium nitride stimulation electrode are affected by fibrous encapsulation in vivo. Electrochemical impedance spectroscopy (EIS), cyclic voltammetry and voltage transient (VT) measurements were performed in vivo and in phosphate buffered saline, where the encapsulation process is absent. EIS was used as a non-invasive measurement to follow the inflammation, healing and encapsulation process. EIS showed that the healing and encapsulation process lasted 3–4 weeks. The VTs increased during the first 3–4 weeks, after which they stabilized. The charge storage capacity (CSC) decreased most during the first 3–4 weeks. The increasing VTs and decreasing CSC during the first 3–4 weeks after implantation of the in vivo electrodes seem related to healing and fibrous encapsulation. It is suggested that the charge injection pathway during the encapsulation process changes, which implies that charge injection limits are underestimated with conventional methods.
      Graphical abstract image

      PubDate: 2016-03-20T02:46:24Z
       
  • Non-invasive estimation of static and pulsatile intracranial pressure from
           transcranial acoustic signals
    • Abstract: Publication date: Available online 17 March 2016
      Source:Medical Engineering & Physics
      Author(s): Alexandra Levinsky, Surik Papyan, Guy Weinberg, Trond Stadheim, Per Kristian Eide
      The aim of the present study was to examine whether a method for estimation of non-invasive ICP (nICP) from transcranial acoustic (TCA) signals mixed with head-generated sounds estimate the static and pulsatile invasive ICP (iICP). For that purpose, simultaneous iICP and mixed TCA signals were obtained from patients undergoing continuous iICP monitoring as part of clinical management. The ear probe placed in the right outer ear channel sent a TCA signal with fixed frequency (621Hz) that was picked up by the left ear probe along with acoustic signals generated by the intracranial compartment. Based on a mathematical model of the association between mixed TCA and iICP, the static and pulsatile nICP values were determined. Total 39 patients were included in the study; the total number of observations for prediction of static and pulsatile iICP were 5789 and 6791, respectively. The results demonstrated a good agreement between iICP/nICP observations, with mean difference of 0.39mmHg and 0.53mmHg for static and pulsatile ICP, respectively. In summary, in this cohort of patients, mixed TCA signals estimated the static and pulsatile iICP with rather good accuracy. Further studies are required to validate whether mixed TCA signals may become useful for measurement of nICP.


      PubDate: 2016-03-20T02:46:24Z
       
  • Dermis mechanical behaviour after different cell removal treatments
    • Abstract: Publication date: Available online 17 March 2016
      Source:Medical Engineering & Physics
      Author(s): Mara Terzini, Cristina Bignardi, Carlotta Castagnoli, Irene Cambieri, Elisabetta M. Zanetti, Alberto L. Audenino
      Human acellular dermal matrices (HADMs) are used in reconstructive surgery as scaffolds promoting autologous tissue regeneration. Critical to the HADM ability to remodel and integrate into the host tissue is the removal of cells while maintaining an intact extracellular architecture. The objective of this work is to develop a methodology to analyse the mechanical properties of HADMs after decellularization to identify its ideal form of treatment and its duration. Two different decellularization techniques were used as a benchmark: the first is a well-established technique (incubation in NaOH for 1–7 weeks), and the second is an innovative technique developed by this research group (incubation in DMEM (Dulbecco's modified Eagle medium) for 1–7 weeks). After decellularization, the specimens underwent uniaxial tensile tests, and experimental data were represented with stress strain curves, calculating both engineering and true values. Mechanical tests have led to the identification of the optimal method (NaOH or DMEM) and duration for the decellularization treatment; differences between engineering and true values can reach 84%, but the engineering values remain useful to make comparisons, providing reliable indications with a simpler experimental set up and data processing.
      Graphical abstract image

      PubDate: 2016-03-20T02:46:24Z
       
  • Objectively quantifying walking ability in degenerative spinal disorder
           patients using sensor equipped smart shoes
    • Abstract: Publication date: Available online 9 March 2016
      Source:Medical Engineering & Physics
      Author(s): Sunghoon Ivan Lee, Eunjeong Park, Alex Huang, Bobak Mortazavi, Jordan Hayward Garst, Nima Jahanforouz, Marie Espinal, Tiffany Siero, Sophie Pollack, Marwa Afridi, Meelod Daneshvar, Saif Ghias, Daniel C. Lu, Majid Sarrafzadeh
      Lumbar spinal stenosis (LSS) is a condition associated with the degeneration of spinal disks in the lower back. A significant majority of the elderly population experiences LSS, and the number is expected to grow. The primary objective of medical treatment for LSS patients has focused on improving functional outcomes (e.g., walking ability) and thus, an accurate, objective, and inexpensive method to evaluate patients’ functional levels is in great need. This paper aims to quantify the functional level of LSS patients by analyzing their clinical information and their walking ability from a 10 m self-paced walking test using a pair of sensorized shoes. Machine learning algorithms were used to estimate the Oswestry Disability Index, a clinically well-established functional outcome, from a total of 29 LSS patients. The estimated ODI scores showed a significant correlation to the reported ODI scores with a Pearson correlation coefficient (r) of 0.81 and p < 3.5 × 10 − 11 . It was further shown that the data extracted from the sensorized shoes contribute most to the reported estimation results, and that the contribution of the clinical information was minimal. This study enables new research and clinical opportunities for monitoring the functional level of LSS patients in hospital and ambulatory settings.


      PubDate: 2016-03-12T01:44:57Z
       
  • Predictive statistical models of baseline variations in 3-D femoral cortex
           morphology
    • Abstract: Publication date: Available online 10 March 2016
      Source:Medical Engineering & Physics
      Author(s): Ju Zhang, Jacqui Hislop-Jambrich, Thor F. Besier
      Quantifying human femoral cortex morphology is important for forensic science, surgical planning, prosthesis design and musculoskeletal modeling. Previous studies have been restricted by traditional zero or one dimensional morphometric measurements at discrete locations. We have used automatic image segmentation and statistical shape modeling methods to create predictive models of baseline 3-D femoral cortex morphology on a statistically significant population. A total of 204 femurs were automatically segmented and measured to obtain 3-D shape, whole-surface cortical thickness, and morphometric measurements. Principal components of shape and cortical thickness were correlated to anthropological data (age, sex, height and body mass) to produce predictive statistical models. We show that predictions of an individual's age, height, and sex can be improved by using 3-D shape and cortical thickness when compared with traditional morphometric measurements. We also show that femoral cortex geometry can be predicted from anthropological data combined with femoral measurements with less than 2.3mm root mean square error, and cortical thickness with less than 0.5mm root mean square error. The predictive models presented offer new ways to infer subject-specific 3-D femur morphology from sparse subject data for biomechanical simulations, and inversely infer subject data from femur morphology for anthropological and forensic studies.
      Graphical abstract image

      PubDate: 2016-03-12T01:44:57Z
       
  • Finite element analysis of the lumbar destabilization following pedicle
           subtraction osteotomy
    • Abstract: Publication date: Available online 8 March 2016
      Source:Medical Engineering & Physics
      Author(s): Claudia Ottardi, Fabio Galbusera, Andrea Luca, Liliana Prosdocimo, Maurizio Sasso, Marco Brayda-Bruno, Tomaso Villa
      This study aims to analyze the destabilization produced following a pedicle subtraction osteotomy (PSO), with a calibrated numerical model. A 30° resection was created on L3 and L4. Range of Motion (ROM) and the force acting on the vertebral body were calculated. Osteotomies consistently increased the ROMs. In the intact model, 87% of the compressive load was acting on the vertebral bodies whereas in the destabilized models all the load was on the fractured surface. Osteotomies at both levels induced a marked instability but the PSO at L4 seemed to have a greater influence on the ROM. Despite the significant deformity corrections which could be achieved with PSO, this technique needs further analyses.


      PubDate: 2016-03-12T01:44:57Z
       
  • Structural identifiability analysis of a cardiovascular system model
    • Abstract: Publication date: Available online 9 March 2016
      Source:Medical Engineering & Physics
      Author(s): Antoine Pironet, Pierre C. Dauby, J. Geoffrey Chase, Paul D. Docherty, James A. Revie, Thomas Desaive
      The six-chamber cardiovascular system model of Burkhoff and Tyberg has been used in several theoretical and experimental studies. However, this cardiovascular system model (and others derived from it) are not identifiable from any output set. In this work, two such cases of structural non-identifiability are first presented. These cases occur when the model output set only contains a single type of information (pressure or volume). A specific output set is thus chosen, mixing pressure and volume information and containing only a limited number of clinically available measurements. Then, by manipulating the model equations involving these outputs, it is demonstrated that the six-chamber cardiovascular system model is structurally globally identifiable. A further simplification is made, assuming known cardiac valve resistances. Because of the poor practical identifiability of these four parameters, this assumption is usual. Under this hypothesis, the six-chamber cardiovascular system model is structurally identifiable from an even smaller dataset. As a consequence, parameter values computed from limited but well-chosen datasets are theoretically unique. This means that the parameter identification procedure can safely be performed on the model from such a well-chosen dataset. Thus, the model may be considered suitable for use in diagnosis.
      Graphical abstract image

      PubDate: 2016-03-12T01:44:57Z
       
  • Sensorized pacifier to evaluate non-nutritive sucking in newborns
    • Abstract: Publication date: April 2016
      Source:Medical Engineering & Physics, Volume 38, Issue 4
      Author(s): Angela Grassi, Francesca Cecchi, Giada Sgherri, Andrea Guzzetta, Luigi Gagliardi, Cecilia Laschi
      We developed a device for an objective measurement of non-nutritive sucking (NNS). NNS is newborns’ spontaneous action that is a predictor of their neural system development and can be adopted as an intervention to train oral feeding skills in preterms. Two miniaturized digital pressure sensors were embedded into a commercial pacifier and the two signals were simultaneously acquired using the Inter-Integrated circuit (I²C) interface. This solution traced a complete pressures profile of the sucking pattern in order to better understand the functional aspects of the two NNS phases, the suction and the expression. Experimental tests with nine newborns confirmed that the sensorized pacifier is an adequate tool for measuring NNS burst-pause patterns. The identified parameters related to the suction/expression rhythmicity could be used as indicators of the NNS ability. This device might be used both for exploring the possible diagnostic data contained in NNS pattern and for monitoring the sucking skills of premature infants.


      PubDate: 2016-03-12T01:44:57Z
       
  • Editorial Board
    • Abstract: Publication date: April 2016
      Source:Medical Engineering & Physics, Volume 38, Issue 4




      PubDate: 2016-03-12T01:44:57Z
       
  • Development of a small wireless device for perspiration monitoring
    • Abstract: Publication date: April 2016
      Source:Medical Engineering & Physics, Volume 38, Issue 4
      Author(s): Kazuhiro Ogai, Masakazu Fukuoka, Kei-ichiro Kitamura, Kiyoshi Uchide, Tetsu Nemoto
      A small and wireless device that can capture the temporal pattern of perspiration by a novel structure of water vapor collection combined with reusable desiccant has been developed. The novel device consists of a small cylindrical case with a temperature/relative humidity sensor, battery-driven data logger, and silica gel (desiccant). Water vapor of perspiration was detected by the change in relative humidity and then adsorbed by silica gel, allowing continuous recording of perspiration within a closed and wireless chamber, which has not been previously achieved. By comparative experiments using the commercially-available perspiration monitoring device, the developed device could measure perspiration as efficiently as the conventional one, with a normalized cross coefficient of 0.738 with 6 s delay and the interclass correlation coefficient [ICC(2, 1)] of 0.84. These results imply a good agreement between the conventional and developed devices, and thus suggest the applicability of the developed device for perspiration monitoring.


      PubDate: 2016-03-12T01:44:57Z
       
  • Upper-limb stroke rehabilitation using electrode-array based functional
           electrical stimulation with sensing and control innovations
    • Abstract: Publication date: Available online 3 March 2016
      Source:Medical Engineering & Physics
      Author(s): M. Kutlu, C.T. Freeman, E. Hallewell, A-M. Hughes, D.S. Laila
      Functional electrical stimulation (FES) has shown effectiveness in restoring upper-limb movement post-stroke when applied to assist participants’ voluntary intention during repeated, motivating tasks. Recent clinical trials have used advanced controllers that precisely adjust FES to assist functional reach and grasp tasks with FES applied to three muscle groups, showing significant reduction in impairment. The system reported in this paper advances the state-of-the-art by: (1) integrating an FES electrode array on the forearm to assist complex hand and wrist gestures; (2) utilising non-contact depth cameras to accurately record the arm, hand and wrist position in 3D; and (3) employing an interactive touch table to present motivating virtual reality (VR) tasks. The system also uses iterative learning control (ILC), a model-based control strategy which adjusts the applied FES based on the tracking error recorded on previous task attempts. Feasibility of the system has been evaluated in experimental trials with 2 unimpaired participants and clinical trials with 4 hemiparetic, chronic stroke participants. The stroke participants attended 17, 1 hour training sessions in which they performed functional tasks, such as button pressing using the touch table and closing a drawer. Stroke participant results show that the joint angle error norm reduced by an average of 50.3% over 6 attempts at each task when assisted by FES.


      PubDate: 2016-03-07T01:01:10Z
       
  • Towards compliant and wearable robotic orthoses: A review of current and
           emerging actuator technologies
    • Abstract: Publication date: Available online 26 February 2016
      Source:Medical Engineering & Physics
      Author(s): Allan Joshua Veale, Shane Quan Xie
      Robotic orthoses, or exoskeletons, have the potential to provide effective rehabilitation while overcoming the availability and cost constraints of therapists. However, current orthosis actuation systems use components designed for industrial applications, not specifically for interacting with humans. This can limit orthoses' capabilities and, if their users’ needs are not adequately considered, contribute to their abandonment. Here, a user centered review is presented on: requirements for orthosis actuators; the electric, hydraulic, and pneumatic actuators currently used in orthoses and their advantages and limitations; the potential of new actuator technologies, including smart materials, to actuate orthoses; and the future of orthosis actuator research.


      PubDate: 2016-03-02T00:20:11Z
       
  • How measurement artifacts affect cerebral autoregulation outcomes: A
           technical note on transfer function analysis
    • Abstract: Publication date: Available online 28 February 2016
      Source:Medical Engineering & Physics
      Author(s): Aisha S.S. Meel-van den Abeelen, Daan L.K. de Jong, Joep Lagro, Ronney B. Panerai, Jurgen A.H.R. Claassen
      Cerebral autoregulation (CA) is the mechanism that aims to maintain adequate cerebral perfusion during changes in blood pressure (BP). Transfer function analysis (TFA), the most reported method in literature to quantify CA, shows large between-study variability in outcomes. The aim of this study is to investigate the role of measurement artifacts in this variation. Specifically, the role of distortion in the BP and/or CBFV measurementon TFA outcomes was investigated. The influence of three types of artifacts on TFA outcomes was studied: loss of signal, motion artifacts, and baseline drifts. TFA metrics of signals without the simulated artifacts were compared with those of signals with artifacts. TFA outcomes scattered highly when more than 10% of BP signal or over 8% of the CBFV signal was lost, or when measurements contained one or more artifacts resulting from head movement. Furthermore, baseline drift affected interpretation of TFA outcomes when the power in the BP signal was 5 times the power in the LF band. In conclusion, loss of signal in BP and loss in CBFV, affects interpretation of TFA outcomes. Therefore, it is vital to validate signal quality to the defined standards before interpreting TFA outcomes.


      PubDate: 2016-03-02T00:20:11Z
       
  • Innovative approach in the development of computer assisted algorithm for
           spine pedicle screw placement
    • Abstract: Publication date: Available online 24 February 2016
      Source:Medical Engineering & Physics
      Author(s): Giovanni F. Solitro, Farid Amirouche
      Pedicle screws are typically used for fusion, percutaneous fixation, and means of gripping a spinal segment. The screws act as a rigid and stable anchor points to bridge and connect with a rod as part of a construct. The foundation of the fusion is directly related to the placement of these screws. Malposition of pedicle screws causes intraoperative complications such as pedicle fractures and dural lesions and is a contributing factor to fusion failure. Computer assisted spine surgery (CASS) and patient-specific drill templates were developed to reduce this failure rate, but the trajectory of the screws remains a decision driven by anatomical landmarks often not easily defined. Current data shows the need of a robust and reliable technique that prevents screw misplacement. Furthermore, there is a need to enhance screw insertion guides to overcome the distortion of anatomical landmarks, which is viewed as a limiting factor by current techniques. The objective of this study is to develop a method and mathematical lemmas that are fundamental to the development of computer algorithms for pedicle screw placement. Using the proposed methodology, we show how we can generate automated optimal safe screw insertion trajectories based on the identification of a set of intrinsic parameters. The results, obtained from the validation of the proposed method on two full thoracic segments, are similar to previous morphological studies. The simplicity of the method, being pedicle arch based, is applicable to vertebrae where landmarks are either not well defined, altered or distorted.


      PubDate: 2016-02-25T23:41:03Z
       
  • Screw insertion in trabecular bone causes peri-implant bone damage
    • Abstract: Publication date: Available online 23 February 2016
      Source:Medical Engineering & Physics
      Author(s): Juri A. Steiner, Stephen J. Ferguson, G. Harry van Lenthe
      Secure fracture fixation is still a major challenge in orthopedic surgery, especially in osteoporotic bone. While numerous studies have investigated the effect of implant loading on the peri-implant bone after screw insertion, less focus has been put on bone damage that may occur due to the screw insertion process itself. Therefore, the aim of this study was to localize and quantify peri-implant bone damage caused by screw insertion. We used non-invasive three-dimensional micro-computed tomography to scan twenty human femoral bone cores before and after screw insertion. After image registration of the pre- and post-insertion scans, changes in the bone micro-architecture were identified and quantified. This procedure was performed for screws with a small thread size of 0.3mm (STS, N =10) and large thread size of 0.6mm (LTS, N =10). Most bone damage occurred within a 0.3mm radial distance of the screws. Further bone damage was observed up to 0.6mm and 0.9mm radial distance from the screw, for the STS and LTS groups, respectively. While a similar amount of bone damage was found within a 0.3mm radial distance for the two screw groups, there was significantly more bone damage for the LTS group than the STS group in volumes of interest between 0.3–0.6mm and 0.6–0.9mm. In conclusion, this is the first study to localize and quantify peri-implant bone damage caused by screw insertion based on a non-invasive, three-dimensional, micro-CT imaging technique. We demonstrated that peri-implant bone damage already occurs during screw insertion. This should be taken into consideration to further improve primary implant stability, especially in low quality osteoporotic bone. We believe that this technique could be a promising method to assess more systematically the effect of peri-implant bone damage on primary implant stability. Furthermore, including peri-implant bone damage due to screw insertion into patient-specific in silico models of implant-bone systems could improve the accuracy of these models.


      PubDate: 2016-02-25T23:41:03Z
       
  • A quantitative measurement method for comparison of seated postures
    • Abstract: Publication date: Available online 23 February 2016
      Source:Medical Engineering & Physics
      Author(s): Susan J Hillman, James Hollington
      This technical note proposes a method to measure and compare seated postures. The three-dimensional locations of palpable anatomical landmarks corresponding to the anterior superior iliac spines, clavicular notch, head, shoulders and knees are measured in terms of x, y and z co-ordinates in the reference system of the measuring apparatus. These co-ordinates are then transformed onto a body-based axis system which allows comparison within-subject. The method was tested on eleven unimpaired adult participants and the resulting data used to calculate a Least Significant Difference (LSD) for the measure, which is used to determine whether two postures are significantly different from one another. The method was found to be sensitive to the four following standardised static postural perturbations: posterior pelvic tilt, pelvic obliquity, pelvic rotation, and abduction of the thighs. The resulting data could be used as an outcome measure for the postural alignment aspect of seating interventions in wheelchairs.


      PubDate: 2016-02-25T23:41:03Z
       
  • Gaussian process prediction of the stress-free configuration of
           pre-deformed soft tissues: Application to the human cornea
    • Abstract: Publication date: Available online 23 February 2016
      Source:Medical Engineering & Physics
      Author(s): Elena Businaro, Harald Studer, Bojan Pajic, Philippe Büchler
      Image-based modeling is a popular approach to perform patient-specific biomechanical simulations. One constraint of this technique is that the shape of soft tissues acquired in-vivo is deformed by the physiological loads. Accurate simulations require determining the existing stress in the tissues or their stress-free configurations. This process is time consuming, which is a limitation to the dissemination of numerical planning solutions to clinical practice. In this study, we propose a method to determine the stress-free configuration of soft tissues using a Gaussian process (GP) regression. The prediction relies on a database of pre-calculated results to enable real time predictions. The application of this technique to the human cornea showed a level of accuracy five to ten times higher than the accuracy of the topographic device used to obtain the patients’ anatomy; results showed that for almost all optical indices, the predicted curvature error did not exceed 0.025D, while the wavefront aberration percentage error did not overcome 5%. In this context, we believe that GP models are suitable for predicting the stress free configuration of the cornea and can be used in planning tools based on patient-specific finite element simulations. Due to the high level of accuracy required in ophthalmology, this approach is likely to be appropriate for other applications requiring the definition of the relaxed shape of soft tissues.


      PubDate: 2016-02-25T23:41:03Z
       
  • Editorial Board
    • Abstract: Publication date: March 2016
      Source:Medical Engineering & Physics, Volume 38, Issue 3




      PubDate: 2016-02-25T23:41:03Z
       
  • Influence of lumbar spine rhythms and intra-abdominal pressure on spinal
           loads and trunk muscle forces during upper body inclination
    • Abstract: Publication date: Available online 24 February 2016
      Source:Medical Engineering & Physics
      Author(s): Rizwan Arshad, Thomas Zander, Marcel Dreischarf, Hendrik Schmidt
      Improved knowledge on spinal loads and trunk muscle forces may clarify the mechanical causes of various spinal diseases and has the potential to improve the current treatment options. Using an inverse dynamic musculoskeletal model, this sensitivity analysis was aimed to investigate the influence of lumbar spine rhythms and intra-abdominal pressure on the compressive and shear forces in L4-L5 disc and the trunk muscle forces during upper body inclination. Based on in vivo data, three different spine rhythms (SRs) were used along with alternative settings (with/without) of intra-abdominal pressure (IAP). Compressive and shear forces in L4-L5 disc as well as trunk muscle forces were predicted by inverse static simulations from standing upright to 55° of intermediate trunk inclination. Alternate model settings of intra-abdominal pressure and different spine rhythms resulted in significant variation of compression (763N) and shear forces (195N) in the L4-L5 disc and in global (454N) and local (156N) trunk muscle forces at maximum flexed position. During upper body inclination, the compression forces at L4-L5 disc were mostly released by IAP and increased for larger intervertebral rotation in a lumbar spine rhythm. This study demonstrated that with various possible assumptions of lumbar spine rhythm and intra-abdominal pressure, variation in predicted loads and muscles forces increase with larger flexion. It is therefore, essential to adapt these model parameters for accurate prediction of spinal loads and trunk muscle forces.


      PubDate: 2016-02-25T23:41:03Z
       
  • Stress shielding in bone of a bone-cement interface
    • Abstract: Publication date: Available online 18 February 2016
      Source:Medical Engineering & Physics
      Author(s): Qing-Hang Zhang, Andrew Cossey, Jie Tong
      Cementation is one of the main fixation methods used in joint replacement surgeries such as Total Knee Replacement (TKR). This work was prompted by a recent retrieval study [1,2], which shows losses up to 75% of the bone stock at the bone-cement interface ten years post TKR. It aims to examine the effects of cementation on the stress shielding of the interfacing bone, when the influence of an implant is removed. A micromechanics finite element study of a generic bone-cement interface is presented here, where bone elements in the partially and the fully interdigitated regions were evaluated under selected load cases. The results revealed significant stress shielding effect in the bone of all bone-cement interface regions, particularly in fully interdigitated region. This finding may be useful in the studies of implant fixation and other related orthopedic treatment strategies.


      PubDate: 2016-02-20T23:01:18Z
       
  • Design, fabrication and characterization of a pure uniaxial microloading
           system for biologic testing
    • Abstract: Publication date: Available online 18 February 2016
      Source:Medical Engineering & Physics
      Author(s): Jonathan D. King, Spencer L. York, Marnie M. Saunders
      The field of mechanobiology aims to understand the role the mechanical environment plays in directing cell and tissue development, function and disease. The empirical aspect of the field requires the development of accurate, reproducible and reliable loading platforms that can apply microprecision mechanical load. In this study we designed, fabricated and characterized a pure uniaxial loading platform capable of testing small synthetic and organic specimens along a horizontal axis. The major motivation for platform development was in stimulating bone cells seeded on elastomeric substrates and soft tissue loading. The biological uses required the development of culturing fixtures and environmental chamber. The device utilizes commercial microactuators, load cells and a rail/carriage block system. Following fabrication, acceptable performance was verified by suture tensile testing.


      PubDate: 2016-02-20T23:01:18Z
       
  • Investigation of hemodynamics during cardiopulmonary bypass: A multiscale
           multiphysics fluid–structure-interaction study
    • Abstract: Publication date: Available online 19 February 2016
      Source:Medical Engineering & Physics
      Author(s): Michael Neidlin, Simon J. Sonntag, Thomas Schmitz-Rode, Ulrich Steinseifer, Tim A S Kaufmann
      Neurological complications often occur during cardiopulmonary bypass (CPB). Hypoperfusion of brain tissue due to diminished cerebral autoregulation (CA) and thromboembolism from atherosclerotic plaque reduce the cerebral oxygen supply and increase the risk of perioperative stroke. To improve the outcome of cardiac surgeries, patient-specific computational fluid dynamic (CFD) models can be used to investigate the blood flow during CPB. In this study, we establish a computational model of CPB which includes cerebral autoregulation and movement of aortic walls on the basis of in vivo measurements. First, the Baroreflex mechanism, which plays a leading role in CA, is represented with a 0-D control circuit and coupled to the 3-D domain with differential equations as boundary conditions. Additionally a two-way coupled fluid–structure interaction (FSI) model with CA is set up. The wall shear stress (WSS) distribution is computed for the whole FSI domain and a comparison to rigid wall CFD is made. Constant flow and pulsatile flow CPB is considered. Rigid wall CFD delivers higher wall shear stress values than FSI simulations, especially during pulsatile perfusion. The flow rates through the supraaortic vessels are almost not affected, if considered as percentages of total cannula output. The developed multiphysic multiscale framework allows deeper insights into the underlying mechanisms during CPB on a patient-specific basis.


      PubDate: 2016-02-20T23:01:18Z
       
  • In vitro assessment of mitral valve function in cyclically pressurized
           porcine hearts
    • Abstract: Publication date: Available online 19 February 2016
      Source:Medical Engineering & Physics
      Author(s): Riccardo Vismara, Alberto M. Leopaldi, Marco Piola, Chiara Asselta, Massimo Lemma, Carlo Antona, Alberto Redaelli, Frans van de Vosse, Marcel Rutten, Gianfranco B. Fiore
      Recent approaches to the in vitro experimental study of cardiac fluid mechanics involve the use of whole biological structures to investigate in the lab novel therapeutic approaches for the treatment of heart pathologies. To enhance reliability and repeatability, the influence of the actuation strategy of the experimental apparatuses on the biomechanics of biological structures needs to be assessed. Using echography and intracardiac high-speed imaging, we compared the mitral valve (MV) anatomo-functional features (coaptation areas/lengths, papillary muscles-valvular plane distances) in two passive-beating-heart mock loops with internal (IPML) or external (EPML) pressurization of the ventricular chamber. Both apparatuses showed fluid dynamic conditions that closely resembled the physiology. The MVs analyzed in the EPML presented coaptation areas and lengths that were systematically higher, and exhibited greater variability from early-to peak-systole, as compared to those in the IPML. Moreover, in the EPML, the MV leaflets exhibited a convexity with high curvature toward the atrium. With the IPML, MV coaptation lengths ranged similar to available clinical data and the papillary muscles-valve plane distances were more stable throughout systole. In conclusion, both the apparatuses allow for reproducing in vitro the left heart hemodynamics, in terms of flow rates and pressures, with proper mitral valve continence. Results suggest that the IPML is more suitable for replicating the physiological MV functioning, while the EPML may have more potential as a model for the study of MV pathologies.


      PubDate: 2016-02-20T23:01:18Z
       
  • Design and evaluation of an actuated knee implant for postoperative
           ligament imbalance correction
    • Abstract: Publication date: Available online 29 January 2016
      Source:Medical Engineering & Physics
      Author(s): A. Collo, S. Almouahed, P. Poignet, C. Hamitouche, E. Stindel
      In Total Knee Arthroplasty (TKA), the collateral ligament tensioning stage cannot be standardised for all patients and relies heavily on the surgeon’s experience and perception. Intraoperative inaccuracies are practically unavoidable and may give rise to severe postoperative complications, leading to the need for revision surgery already a few years after primary TKA. This work proposes a novel instrumented tibial component able to detect collateral ligament laxity conditions right after primary TKA and, if needed, to compensate for them in the postoperative period. A miniaturised actuation system, designed to be embedded in the tibial baseplate, was initially evaluated by means of 3D simulations and then fabricated as a full-scale prototype. Stability and force sensors tests carried out on a knee simulator allowed to assess the effectiveness of the proposed design under normal working conditions and provided valuable insights for future work and improvements.


      PubDate: 2016-02-08T20:22:50Z
       
  • Penetration of an artificial arterial thromboembolism in a live animal
           using an intravascular therapeutic microrobot system
    • Abstract: Publication date: Available online 5 February 2016
      Source:Medical Engineering & Physics
      Author(s): Semi Jeong, Hyunchul Choi, Gwangjun Go, Cheong Lee, Kyung Seob Lim, Doo Sun Sim, Myung Ho Jeong, Seong Young Ko, Jong-Oh Park, Sukho Park
      The biomedical applications of wireless robots are an active area of study. In addition to moving to a target lesion, wireless locomotive robots can deliver a therapeutic drug for a specific disease. Thus, they hold great potential as therapeutic devices in blood vessel diseases, such as thrombi and occlusions, and in other diseases, such as cancer and inflammation. During a percutaneous coronary intervention (PCI), surgeons wear a heavy shielding cloth. However, they cannot escape severe radiation exposure owing to unstable shielding. They may also suffer from joint pains because of the weight of the shielding cloth. In addition, the catheters in PCIs are controlled by the surgeon's hand. Thus, they lack steering ability. A new intravascular therapeutic system is needed to address these problems in conventional PCIs. We developed an intravascular therapeutic microrobot system (ITMS) using an electromagnetic actuation (EMA) system with bi-plane X-ray devices that can remotely control a robot in blood vessels. Using this proposed ITMS, we demonstrated the locomotion of the robot in abdominal and iliac arteries of a live pig by the master-slave method. After producing an arterial thromboembolism in a live pig in a partial iliac artery, the robot moved to the target lesion and penetrated by specific motions (twisting and hammering) of the robot using the proposed ITMS. The results reveal that the proposed ITMS can realize stable locomotion (alignment and propulsion) of a robot in abdominal and iliac arteries of a live pig. This can be considered the first preclinical trial of the treatment of an artificial arterial thromboembolism by penetration of a blood clot.


      PubDate: 2016-02-08T20:22:50Z
       
  • In-situ mechanical behavior and slackness of the anterior cruciate
           ligament at multiple knee flexion angles
    • Abstract: Publication date: Available online 22 December 2015
      Source:Medical Engineering & Physics
      Author(s): H.H. Rachmat, D. Janssen, G.J. Verkerke, R.L. Diercks, N. Verdonschot
      In this study the in-situ tensile behavior and slackness of the anterior cruciate ligament (ACL) was evaluated at various knee flexion angles. In four cadaveric knees the ACL was released at the tibial insertion, after which it was re-connected to a tensiometer. After pre-tensioning (10 N) the ACL in full-extension, the knee was flexed from 0° to 150° at 15° increments, during which the ACL tension was measured. At each angle the ACL was subsequently elongated and shortened under displacement control, while measuring the ACL tension. In this manner, the pre-tension or the slackness, and the mechanical response of the ACL were measured. All ACL's displayed a higher tension at low (0°–60°) and high (120°–150°) flexion angles. The ACL slackness depended on flexion angle, with the highest slackness found at 75°–90°. Additionally, the ACL stiffness also varied with flexion angle, with the ACL behaving stiffer at low and high flexion angels. In general, the ACL was stiffest at 150°, and most compliant at 90°. The results of this study contribute to understanding the mechanical behavior of the ACL in-situ, and may help tuning and validating computational knee models studying ACL function.


      PubDate: 2015-12-26T03:55:56Z
       
 
 
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