kth.sePublikationer
Ändra sökning
Avgränsa sökresultatet
123456 1 - 50 av 268
RefereraExporteraLänk till träfflistan
Permanent länk
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf
Träffar per sida
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sortering
  • Standard (Relevans)
  • Författare A-Ö
  • Författare Ö-A
  • Titel A-Ö
  • Titel Ö-A
  • Publikationstyp A-Ö
  • Publikationstyp Ö-A
  • Äldst först
  • Nyast först
  • Skapad (Äldst först)
  • Skapad (Nyast först)
  • Senast uppdaterad (Äldst först)
  • Senast uppdaterad (Nyast först)
  • Disputationsdatum (tidigaste först)
  • Disputationsdatum (senaste först)
  • Standard (Relevans)
  • Författare A-Ö
  • Författare Ö-A
  • Titel A-Ö
  • Titel Ö-A
  • Publikationstyp A-Ö
  • Publikationstyp Ö-A
  • Äldst först
  • Nyast först
  • Skapad (Äldst först)
  • Skapad (Nyast först)
  • Senast uppdaterad (Äldst först)
  • Senast uppdaterad (Nyast först)
  • Disputationsdatum (tidigaste först)
  • Disputationsdatum (senaste först)
Markera
Maxantalet träffar du kan exportera från sökgränssnittet är 250. Vid större uttag använd dig av utsökningar.
  • 1.
    Abouzayed, Ayman
    et al.
    Uppsala Univ, Dept Med Chem, S-75183 Uppsala, Sweden..
    Borin, Jesper
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Proteinvetenskap, Proteinteknologi.
    Lundmark, Fanny
    Uppsala Univ, Dept Med Chem, S-75183 Uppsala, Sweden..
    Rybina, Anastasiya
    Russian Acad Sci, Canc Res Inst, Tomsk Natl Res Med Ctr, Dept Nucl Med, Tomsk 634009, Russia.;Tomsk Polytech Univ, Res Sch Chem & Appl Biomed Sci, Res Ctr Oncotheranost, Tomsk 634050, Russia..
    Hober, Sophia
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Proteinvetenskap.
    Zelchan, Roman
    Russian Acad Sci, Canc Res Inst, Tomsk Natl Res Med Ctr, Dept Nucl Med, Tomsk 634009, Russia.;Tomsk Polytech Univ, Res Sch Chem & Appl Biomed Sci, Res Ctr Oncotheranost, Tomsk 634050, Russia..
    Tolmachev, Vladimir
    Uppsala Univ, Dept Immunol Genet & Pathol, S-75237 Uppsala, Sweden..
    Chernov, Vladimir
    Russian Acad Sci, Canc Res Inst, Tomsk Natl Res Med Ctr, Dept Nucl Med, Tomsk 634009, Russia..
    Orlova, Anna
    Uppsala Univ, Dept Med Chem, S-75183 Uppsala, Sweden.;Uppsala Univ, Sci Life Lab, S-75237 Uppsala, Sweden..
    The GRPR Antagonist [Tc-99m]Tc-maSSS-PEG(2)-RM26 towards Phase I Clinical Trial: Kit Preparation, Characterization and Toxicity2023Ingår i: Diagnostics, ISSN 2075-4418, Vol. 13, nr 9, s. 1611-, artikel-id 1611Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Gastrin-releasing peptide receptors (GRPRs) are overexpressed in the majority of primary prostate tumors and in prostatic lymph node and bone metastases. Several GRPR antagonists were developed for SPECT and PET imaging of prostate cancer. We previously reported a preclinical evaluation of the GRPR antagonist [Tc-99m]Tc-maSSS-PEG2-RM26 (based on [D-Phe(6), Sta(13), Leu(14)-NH2]BBN(6-14)) which bound to GRPR with high affinity and had a favorable biodistribution profile in tumor-bearing animal models. In this study, we aimed to prepare and test kits for prospective use in an early-phase clinical study. The kits were prepared to allow for a one-pot single-step radiolabeling with technetium-99m pertechnetate. The kit vials were tested for sterility and labeling efficacy. The radiolabeled by using the kit GRPR antagonist was evaluated in vitro for binding specificity to GRPR on PC-3 cells (GRPR-positive). In vivo, the toxicity of the kit constituents was evaluated in rats. The labeling efficacy of the kits stored at 4 degrees C was monitored for 18 months. The biological properties of [Tc-99m]Tc-maSSS-PEG2-RM26, which were obtained after this period, were examined both in vitro and in vivo. The one-pot (gluconic acid, ethylenediaminetetraacetic acid, stannous chloride, and maSSS-PEG(2)-RM26) single-step radiolabeling with technetium-99m was successful with high radiochemical yields (>97%) and high molar activities (16-24 MBq/nmol). The radiolabeled peptide maintained its binding properties to GRPR. The kit constituents were sterile and non-toxic when tested in living subjects. In conclusion, the prepared kit is considered safe in animal models and can be further evaluated for use in clinics.

  • 2. Abrahamsson, S.
    et al.
    Blom, Hans
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik.
    Agostinho, A.
    Jans, Daniel
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik.
    Jost, A.
    Müller, M.
    Nilsson, Linnea
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik.
    Bernhem, K.
    Lambert, T. J.
    Heintzmann, R.
    Brismar, Hjalmar
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik.
    Multifocus structured illumination microscopy for fast volumetric super-resolution imaging2017Ingår i: Biomedical Optics Express, E-ISSN 2156-7085, Vol. 8, nr 9, s. 4135-4140, artikel-id #294866Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We here report for the first time the synergistic implementation of structured illumination microscopy (SIM) and multifocus microscopy (MFM). This imaging modality is designed to alleviate the problem of insufficient volumetric acquisition speed in superresolution biological imaging. SIM is a wide-field super-resolution technique that allows imaging with visible light beyond the classical diffraction limit. Employing multifocus diffractive optics we obtain simultaneous wide-field 3D imaging capability in the SIM acquisition sequence, improving volumetric acquisition speed by an order of magnitude. Imaging performance is demonstrated on biological specimens.

  • 3.
    Abtahi, Farhad
    et al.
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik, Medicinska sensorer, signaler och system.
    Ji, Guangchao
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik, Medicinska sensorer, signaler och system.
    Lu, Ke
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik, Medicinska sensorer, signaler och system.
    Rödby, Kristian
    Högskolan i Borås, Akademin för textil, teknik och ekonomi.
    Björlin, Anders
    Kiwok AB.
    Östlund, Anders
    Kiwok AB.
    Seoane, Fernando
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik, Medicinska sensorer, signaler och system. Högskolan i Borås, Akademin för vård, arbetsliv och välfärd.
    Lindecrantz, Kaj
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik, Medicinska sensorer, signaler och system.
    Textile-Electronic Integration in Wearable Measurement Garments for Pervasive Healthcare Monitoring2015Konferensbidrag (Övrigt vetenskapligt)
  • 4.
    Alander, Jarmo
    et al.
    Department of Electrical Engineering and Automation, University of Vaasa.
    Autere, Antti
    Department of Electrical Engineering and Automation, University of Vaasa.
    Kanniainen, Olli
    Department of Electrical Engineering and Automation, University of Vaasa.
    Koljonen, Janne
    Department of Electrical Engineering and Automation, University of Vaasa.
    Nordling, Torbjörn E M
    Department of Electrical Engineering and Automation, University of Vaasa.
    Välisuo, Petri
    Department of Electrical Engineering and Automation, University of Vaasa.
    Near infrared wavelength relevance detection of ultraviolet radiation-induced erythema2008Ingår i: Journal of Near Infrared Spectroscopy, ISSN 0967-0335, E-ISSN 1751-6552, Vol. 16, nr 3, s. 233-241Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The acute effects of sun-bathing on the near-infrared absorption spectra of human skin were studied by exposing the shoulders of a male test subject to bright Finnish high summer mid-day sun. The spectra were measured before, immediately after and for several days after exposure. Four different spectral. processing and classification methods were applied to the data set to identify differences caused by exposure to the sun. The spectrophotometer and measuring procedure were found to cause some systematic errors, calling for further development, even though they could, to a large extent, be compensated for computationally. Spectral regions indicating ultraviolet radiation-induced erythema were Located and the degree of erythema could be predicted correctly but the signal is weak. This paper discusses promising wavelength selection methods to study the dermal effects of exposure to the sun, as well as difficulties and remedies of near infrared spectroscopic measurements of the skin.

  • 5. Ambrosi, D.
    et al.
    Ateshian, G. A.
    Arruda, E. M.
    Cowin, S. C.
    Dumais, J.
    Goriely, A.
    Holzapfel, Gerhard A.
    KTH, Skolan för teknikvetenskap (SCI), Mekanik, Biomekanik.
    Humphrey, J. D.
    Kemkemer, R.
    Kuhl, E.
    Olberding, J. E.
    Taber, L. A.
    Garikipati, K.
    Perspectives on biological growth and remodeling2011Ingår i: Journal of the mechanics and physics of solids, ISSN 0022-5096, E-ISSN 1873-4782, Vol. 59, nr 4, s. 863-883Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    The continuum mechanical treatment of biological growth and remodeling has attracted considerable attention over the past fifteen years. Many aspects of these problems are now well-understood, yet there remain areas in need of significant development from the standpoint of experiments, theory, and computation. In this perspective paper we review the state of the field and highlight open questions, challenges, and avenues for further development.

  • 6. Aslund, Magnus
    et al.
    Fredenberg, Erik
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Medicinsk bildfysik.
    Telman, M.
    Danielsson, Mats
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Medicinsk bildfysik.
    Detectors for the future of X-ray imaging2010Ingår i: Radiation Protection Dosimetry, ISSN 0144-8420, E-ISSN 1742-3406, Vol. 139, nr 1-3, s. 327-333Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In recent decades, developments in detectors for X-ray imaging have improved dose efficiency. This has been accomplished with for example, structured scintillators such as columnar CsI, or with direct detectors where the X rays are converted to electric charge carriers in a semiconductor. Scattered radiation remains a major noise source, and fairly inefficient anti-scatter grids are still a gold standard. Hence, any future development should include improved scatter rejection. In recent years, photon-counting detectors have generated significant interest by several companies as well as academic research groups. This method eliminates electronic noise, which is an advantage in low-dose applications. Moreover, energy-sensitive photon-counting detectors allow for further improvements by optimising the signal-to-quantum-noise ratio, anatomical background subtraction or quantitative analysis of object constituents. This paper reviews state-of-the-art photon-counting detectors, scatter control and their application in diagnostic X-ray medical imaging. In particular, spectral imaging with photon-counting detectors, pitfalls such as charge sharing and high rates and various proposals for mitigation are discussed.

    Ladda ner fulltext (pdf)
    fulltext
  • 7.
    Asplund, Maria
    KTH, Skolan för teknik och hälsa (STH), Neuronik.
    Conjugated Polymers for Neural Interfaces: Prospects, possibilities and future challenges2009Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Within the field of neuroprosthetics the possibility to use implanted electrodes for communication with the nervous system is explored. Much effort is put into the material aspects of the electrode implant to increase charge injection capacity, suppress foreign body response and build micro sized electrode arrays allowing close contact with neurons. Conducting polymers, in particular poly(3,4-ethylene dioxythiophene) (PEDOT), have been suggested as materials highly interesting for such neural communication electrodes. The possibility to tailor the material both mechanically and biochemically to suit specific applications, is a substantial benefit with polymers when compared to metals. PEDOT also have hybrid charge transfer properties, including both electronic and ionic conduction, which allow for highly efficient charge injection.

     

    Part of this thesis describes a method of tailoring PEDOT through exchanging the counter ion used in electropolymerisation process. Commonly used surfactants can thereby be excluded and instead, different biomolecules can be incorporated into the polymer. The electrochemical characteristics of the polymer film depend on the ion. PEDOT electropolymerised with heparin was here determined to have the most advantageous properties. In vitro methods were applied to confirm non-cytotoxicity of the formed PEDOT:biomolecular composites. In addition, biocompatibility was affirmed for PEDOT:heparin by evaluation of inflammatory response and neuron density when implanted in rodent cortex.

     

    One advantage with PEDOT often stated, is its high stability compared to other conducting polymers. A battery of tests simulating the biological environment was therefore applied to investigate this stability, and especially the influence of the incorporated heparin. These tests showed that there was a decline in the electroactivity of PEDOT over time. This also applied in phosphate buffered saline at body temperature and in the absence of other stressors. The time course of degradation also differed depending on whether the counter ion was the surfactant polystyrene sulphonate or heparin, with a slightly better stability for the former.

     

    One possibility with PEDOT, often overlooked for biological applications, is the use of its semi conducting properties in order to include logic functions in the implant. This thesis presents the concept of using PEDOT electrochemical transistors to construct textile electrode arrays with in-built multiplexing. Using the electrolyte mediated interaction between adjacent PEDOT coated fibres to switch the polymer coat between conducting and non conducting states, then transistor function can be included in the conducting textile. Analogue circuit simulations based on experimentally found transistor characteristics proved the feasibility of these textile arrays. Developments of better polymer coatings, electrolytes and encapsulation techniques for this technology, were also identified to be essential steps in order to make these devices truly useful.

     

    In summary, this work shows the potential of PEDOT to improve neural interfaces in several ways. Some weaknesses of the polymer and the polymer electronics are presented and this, together with the epidemiological data, should point in the direction for future studies within this field.

    Ladda ner fulltext (pdf)
    FULLTEXT01
  • 8.
    Ayllon, David
    et al.
    Department of Signal Theory and Communications.
    Seoane, Fernando
    KTH, Skolan för teknik och hälsa (STH), Medicinska sensorer, signaler och system (MSSS).
    Gil-Pita, Roberto
    Department of Signal Theory and Communications.
    Cole equation and parameter estimation from electrical bioimpedance spectroscopy measurements: A comparative study2009Ingår i: EMBC: 2009 ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY, VOLS 1-20, Buenos Aires: IEEE Engineering in Medicine and Biology , 2009, s. 3779-3782Konferensbidrag (Refereegranskat)
    Abstract [en]

    Since there are several applications of Electrical Bioimpedance (EBI) that use the Cole parameters as base of the analysis, to fit EBI measured data onto the Cole equation is a very common practice within Multifrequency-EBI and spectroscopy. The aim of this paper is to compare different fitting methods for EBI data in order to evaluate their suitability to fit the Cole equation and estimate the Cole parameters. Three of the studied fittings are based on the use of Non-Linear Least Squares on the Cole model, one using the real part only, a second using the imaginary part and the third using the complex impedance. Furthermore, a novel fitting method done on the impedance plane, without using any frequency information has been implemented and included in the comparison. Results show that the four methods perform relatively well but the best fitting in terms of standard error of estimate is the fitting obtained from the resistance only. The results support the possibility of measuring only the resistive part of the bioimpedance to accurately fit Cole equation and estimate the Cole parameters, with entailed advantages.

  • 9.
    Bartholomay, S.
    et al.
    Germany.
    Marten, D.
    Germany.
    Martinez, Mariano Sanchez
    KTH. TU Berlin, Berlin, Germany.
    Alber, J.
    Germany.
    Pechlivanoglou, G.
    Germany.
    Nayeri, C. N.
    Germany.
    Paschereit, C. O.
    Germany.
    Klein, A. C.
    Germany.
    Lutz, T.
    Kramer, E.
    Cross-talk compensation for blade root flap-and edgewise moments on an experimental research wind turbine and comparison to numerical results2018Ingår i: Proceedings of the ASME Turbo Expo, ASME Press, 2018Konferensbidrag (Refereegranskat)
    Abstract [en]

    In the current paper a method to correct cross-talk effects for strain-gauge measurements is presented. Themethod is demonstrated on an experimental horizontal axiswind turbine. The procedure takes cross-moments (flapwise on edgewise moments and vice versa) as well as axialacceleration into account. The results from the experimental setup are compared to numerical URANS calculationsand the medium-fidelity code Qblade for a baseline caseand two yawed inflow situations.

  • 10. Bauer, Margit
    et al.
    Mazza, Edoardo
    Jabareen, Mahmood
    Sultan, Leila
    Bajka, Michael
    Lang, Uwe
    Zimmermann, Roland
    Holzapfel, Gerhard A.
    KTH, Skolan för teknikvetenskap (SCI), Hållfasthetslära (Inst.), Hållfasthetslära (Avd.).
    Assessment of the in vivo biomechanical properties of the human uterine cervix in pregnancy using the aspiration test A feasibility study2009Ingår i: European Journal of Obstetrics, Gynecology, and Reproductive Biology, ISSN 0301-2115, E-ISSN 1872-7654, Vol. 144, s. S77-S81Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Objective: To date no diagnostic tool is yet available to objectively assess the in vivo biomechanical properties of the uterine cervix during gestation. Methods: We show the first clinical application of an aspiration device to assess the in vivo biomechanical properties of the cervix in pregnancy with the aim to describe the physiological biomechanical changes throughout gestation in order to eventually detect pregnant women at risk for cervical insufficiency (CI). Results: Out of 15 aspiration measurements, 12 produced valid results. The stiffness values were in the range between 0.013 and 0.068 bar/mm. The results showed a good reproducibility of the aspiration test. In our previous test series on non-pregnant cervices our repetitive measurements showed a standard deviation of > 20% compared to <+/- 10% to our data on pregnant cervices. Stiffness values are decreasing with gestational age which indicates a progressive softening of cervical tissue towards the end of pregnancy. Three pregnant women had two subsequent measurements within a time interval of four weeks. Decreasing stiffness values in the range of 20% were recorded. Discussion: This preliminary study on the clinical practicability of aspiration tests showed promising results in terms of reproducibility (reliability) and clinical use (feasibility). Ongoing studies will provide further insights on its usefulness in clinical practice and in the detection of substantial changes of the cervix in pregnancy indicative for threatened preterm birth or cervical insufficiency.

  • 11.
    Besic, Alisa
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Medicinteknik och hälsosystem.
    Ogeborg, Martin
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Medicinteknik och hälsosystem.
    Development of Reliability Test Rigs for Total Artificial Heart Pumps2022Självständigt arbete på grundnivå (högskoleexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Det artificiella hjärtats långsiktiga prestanda måste demonstreras. Tillförlitlighetstester utförs för att mäta pumparnas förmåga att fungera i månader eller år utan att gå sönder. Real Heart bygger för närvarande testriggar för detta ändamål. Programvara för att dokumentera testriggens förhållanden behövs också. Därför är syftet med denna studie att hjälpa företaget med att utveckla programvara för tillförlitlighetstestriggar. 

    Programvaran är skriven i LabVIEW och används på en CompactRIO-kontroller. Den kommer inkludera provtagning av sensordata, loggning och alarm. Dessutom är en PC-instrumentpanel konstruerad för övervakning av realtidsdata, granskning av loggar samt kontroll av datainsamling.

    Resultaten av denna studie utgör en grund för testriggens programvara. Den har en modulär arkitektur som möjliggör framtida uppskalning. Utvecklingsprocessen involverar studier av hårdvara/programvara, upprättande av en referensdesign, samt att bygga och validera varje modul genom testsimuleringar. Datainsamling genomförs med NI-DAQmx API. Den har automatisk konfiguration för temperatur, samt anpassad signalskalning av tryck- och flödesgivare. Designmönstret producent/konsument implementerades för gruppering av data, samt synkronisering för loggning och alarm.

    Ladda ner fulltext (pdf)
    Development of Reliability Test Rigs for Total Artificial Heart Pumps
  • 12.
    Biasetti, Jacopo
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Hållfasthetslära (Inst.), Biomekanik.
    Gasser, T. Christian
    KTH, Skolan för teknikvetenskap (SCI), Hållfasthetslära (Inst.), Biomekanik.
    Auer, Martin
    VASCOPS GmbH, Graz, Austria.
    Hedin, Ulf
    Department of Molecular Medicine and Surgery, Karolinska Universty Hospital, Stockholm, Sweden.
    Labruto, Fausto
    Department of Radoilogy, Karolinska University Hospital, Stockholm, Sweden.
    Hemodynamics of the Normal Aorta Compared to Fusiform and Saccular Abdominal Aortic Aneurysms with Emphasis on a Potential Thrombus Formation Mechanism2010Ingår i: Annals of Biomedical Engineering, ISSN 0090-6964, E-ISSN 1573-9686, Vol. 38, nr 2, s. 380-390Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Abdominal Aortic Aneurysms (AAAs), i.e., focal enlargements of the aorta in the abdomen are frequently observed in the elderly population and their rupture is highly mortal. An intra-luminal thrombus is found in nearly all aneurysms of clinically relevant size and multiply affects the underlying wall. However, from a biomechanical perspective thrombus development and its relation to aneurysm rupture is still not clearly understood. In order to explore the impact of blood flow on thrombus development, normal aortas (n = 4), fusiform AAAs (n = 3), and saccular AAAs (n = 2) were compared on the basis of unsteady Computational Fluid Dynamics simulations. To this end patient-specific luminal geometries were segmented from Computerized Tomography Angiography data and five full heart cycles using physiologically realistic boundary conditions were analyzed. Simulations were carried out with computational grids of about half a million finite volume elements and the Carreau-Yasuda model captured the non-Newtonian behavior of blood. In contrast to the normal aorta the flow in aneurysm was highly disturbed and, particularly right after the neck, flow separation involving regions of high streaming velocities and high shear stresses were observed. Naturally, at the expanded sites of the aneurysm average flow velocity and wall shear stress were much lower compared to normal aortas. These findings suggest platelets activation right after the neck, i.e., within zones of pronounced recirculation, and platelet adhesion, i.e., thrombus formation, downstream. This mechanism is supported by recirculation zones promoting the advection of activated platelets to the wall.

  • 13.
    Bjällmark, Anna
    et al.
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik.
    Larsson, Matilda
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik.
    Brodin, Lars-Åke
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik.
    Nowak, Jacek
    Lind, Britta
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik.
    Hayashi, Shirley
    Mazza do Nascimento, Marcelo
    Riella, Miquel
    Seeberger, Astrid
    Effects of hemodialysis on the cardiovascular system: Quantitative analysis using wave intensity wall analysis and tissue velocity imaging2010Ingår i: Heart and Vessels, ISSN 0910-8327, E-ISSN 1615-2573Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Cardiovascular disease is the leading cause of death in patients with end stage renal disease (ESRD). The aim of this study was to investigate the changes in cardiovascular function induced by a single session of hemodialysis (HD) by the analysis of cardiovascular dynamics using wave intensity wall analysis (WIWA) and of systolic and diastolic myocardial function using tissue velocity imaging (TVI). Grey-scale cine loops of the left common carotid artery, conventional echocardiography and TVI images of the left ventricle were acquired before and after HD in 45 patients (17 women, mean age 54) with ESRD. The WIWA indexes, W1 preload-adjusted W1, W2 and preload-adjusted W2, and the TVI variables, isovolumic contraction velocity (IVCV), isovolumic contraction time (IVCT), peak systolic velocity (PSV), displacement, isovolumic relaxation velocity (IVRV), isovolumic relaxation time (IVRT), peak early diastolic velocity (E’) and peak late diastolic velocity (A’), were compared before and after HD. The WIWA measurements showed significant increases in W1 (p < 0.05) and preload-adjusted W1 (p < 0.01) after HD. W2 was significantly decreased (p < 0.05) after HD, whereas the change in preload-adjusted W2 was not significant. Systolic velocities, IVCV (p < 0.001) and PSV (p < 0.01), were increased after HD, whereas the AV-plane displacement were decreased (p < 0.01). For the measured diastolic variables, E’ was significantly decreased (p < 0.01) and IVRT was significantly prolonged (p < 0.05), after HD. A few correlations were found between WIWA and TVI variables. The WIWA and TVI measurements indicate that a single session of HD improves systolic function. The load dependency of the diastolic variables seems to be more pronounced than for the systolic variables. Preload-adjusted wave intensity indexes may contribute in the assessment of true LV contractility and relaxation.

  • 14.
    Bjällmark, Anna
    et al.
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik.
    Larsson, Matilda
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik.
    Shahgaldi, Kambiz
    Lind, Britta
    KTH, Skolan för teknik och hälsa (STH).
    Winter, Reidar
    Brodin, Lars-Ake
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik.
    Differences in myocardial velocities during supine and upright exercise stress echocardiography in healthy adults2009Ingår i: Clinical Physiology and Functional Imaging, ISSN 1475-0961, E-ISSN 1475-097X, Vol. 29, nr 3, s. 216-223Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Tissue Velocity Imaging (TVI) is a method for quantitative analysis of longitudinal myocardial velocities, which can be used during exercise and pharmacological stress echocardiography. It is of interest to evaluate cardiac response to different types of stress tests and the differences between upright and supine bicycle exercise tests have not been fully investigated. Therefore, the aim of this study was to compare cardiac response during supine and upright exercise stress tests. Twenty young healthy individuals underwent supine and upright stress test. The initial workload was set to 30 W and was increased every minute by a further 30 W until physical exhaustion. Tissue Doppler data from the left ventricle were acquired at the end of every workload level using a GE Vivid7 Dimension system (> 200 frames s(-1)). In the off-line processing, isovolumic contraction velocity (IVCV), peak systolic velocity (PSV), isovolumic relaxation velocity (IVRV), peak early diastolic velocity (E') and peak late diastolic velocity (A') were identified at every workload level. No significant difference between the tests was found in PSV. On the contrary, E' was shown to be significantly higher (P < 0.001) during supine exercise than during upright exercise and IVRV was significantly lower (P < 0.001) during supine exercise compared to upright exercise. Upright and supine exercise stress echocardiography give a comparable increase in measured systolic velocities and significant differences in early diastolic velocities.

  • 15.
    Bjällmark, Anna
    et al.
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik.
    Lind, Britta
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik.
    Brodin, Lars-Åke
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik.
    Peolsson, Michael
    KTH, Skolan för teknik och hälsa (STH).
    Shahgaldi, Kambiz
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik.
    Nowak, Jacek
    Ultrasonographic strain imaging is superior to conventional non-invasive measures of vascular stiffness in the detection of age-dependent differences in the mechanical properties of the common carotid artery2010Ingår i: European Journal of Echocardiography, ISSN 1525-2167, E-ISSN 1532-2114, Vol. 11, nr 7, s. 630-636Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Aims: Elastic properties of large arteries have been shown to deteriorate with age and in the presence of atherosclerotic vascular disease. In this study, the performance of ultrasonographic strain measurements was compared to conventional measures of vascular stiffness in the detection of age-dependent differences in the elastic properties of the common carotid artery.

    Methods and results: In 10 younger (25-28 years, 4 women) and 10 older (50-59 years, 4 women) healthy individuals, global and regional circumferential and radial strain variables were measured in the short-axis view of the right common carotid artery using ultrasonographic two-dimensional (2D) strain imaging with recently introduced speckle tracking technique. Conventional elasticity variables, elastic modulus (Ep) and β stiffness index, were calculated using M-mode sonography and non-invasive blood pressure measurements. Global and regional circumferential systolic strain and strain rate values were significantly higher (p < 0.001, p < 0.01 for regional late systolic strain rate) in the younger individuals, whereas the values of conventional elasticity variables in the same group were lower (p < 0.05). Among all strain and conventional elasticity variables, principal component analysis and its regression extension identified only circumferential systolic strain variables as contributing significantly to the observed discrimination between the younger and older age groups.

    Conclusion: Ultrasonographic 2D-strain imaging is a sensitive method for the assessment of elastic properties in the common carotid artery, being in this respect superior to conventional measures of vascular elasticity. The method has potential to become a valuable non-invasive tool in the detection of early atherosclerotic vascular changes.

  • 16.
    Boltshauser, Rasmus
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Medicinteknik och hälsosystem.
    Development of a Novel Device for Optimal Sample Blood Volume Collection from Patients with Sepsis2020Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    When performing sepsis diagnosis, the most important preanalytical variable is blood volume. Too little blood increases the risk for false negatives whereas overfilling causes increased risk for false positives. Even though this fact is known, there are case studies showing that in a majority of tests, the taken blood sample volume is not the recommended amount. As previously tried methods have been limited in their ability to tackle the problem this study aimed at creating a technical device to aid healthcare providers with blood volume sample collection. As a base, the double diamond approach by the Design Council was used. This design approach splits up the design process in four distinctly different phases (discover, define, develop, and deliver) all using their own methods to aid the creative process.

    After completing the discover and define phase it was determined that a non-contact capacitance liquid level sensor could operate as an ideal blood volume sample device. During the development and delivery phase prototypes were created and evaluated. The final results of this work could not give conclusive evidence concerning if a non-contact liquid level sensor could operate as an ideal blood volume collection device. The methodological approach used in this thesis can be used as inspiration for a designer to create a device for a similar or different purpose. Moreover, information from this thesis can also work as reference material to develop a device to perform ideal blood volume sample collection.

    Such a device would have the potential to be an essential part of the everyday workflow in sample collection from patients with sepsis worldwide and would aid in ensures effective and fast diagnostics.

    Ladda ner fulltext (pdf)
    fulltext
  • 17. Borsbo, Bjorn
    et al.
    Gerdle, Bjorn
    Peolsson, Michael
    KTH, Skolan för teknik och hälsa (STH).
    Impact of the interaction between self-efficacy, symptoms and catastrophising on disability, quality of life and health in with chronic pain patients2010Ingår i: Disability and Rehabilitation, ISSN 0963-8288, E-ISSN 1464-5165, Vol. 32, nr 17, s. 1387-1396Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Purpose. To investigate the interactions between self-efficacy - including subcomponents - and symptoms (pain, depression and anxiety), catastrophising, disability, quality of life and health in a population of patients with chronic pain. Method. The study used 433 patients with chronic pain including 47 patients with spinal cord injury-related pain, 150 patients with chronic whiplash-associated disorders and 236 patients with fibromyalgia. The participants answered a postal questionnaire that provided background data, pain intensity and duration and psychological- and health-related variables. Results. In the multivariate context, depression, anxiety, catastrophising and disability were intercorrelated. Self-efficacy correlated positively with variables of quality of life and general health. These two groups of variables were negatively correlated. The pain variables - duration of pain, pain intensity and spreading of pain - formed a third group of variables. Self-efficacy function was negatively correlated to these three pain variables. When regressing disability, quality of life and health, we found that self-efficacy had a positive impact whereas symptoms, catastrophising and pain had a negative influence on these aspects. Different patterns of influencing variables were discerned for the three different analyses, and specific patterns of the subscales of self-efficacy corresponded to specific patterns of negative factors for the outcome of disability, quality of life and health. Conclusion. There is a complex interaction of psychological factors and symptoms and their positive and negative influence on disability, quality of life and health. The results indicate that it might be important to assess and influence both enhancing and detoriating factors to ensure an effective pain management programme.

  • 18.
    Buendia, Ruben
    et al.
    KTH, Skolan för teknik och hälsa (STH), Medicinska sensorer, signaler och system (MSSS).
    Gil-Pita, Roberto
    Department of Theory of the Signal and Communications.
    Seoane, Fernando
    KTH, Skolan för teknik och hälsa (STH), Medicinska sensorer, signaler och system (MSSS).
    Cole Parameter Estimation from the Modulus of the Electrical Bioimpeadance for Assessment of Body Composition: A Full Spectroscopy Approach2011Ingår i: Journal of Electrical Bioimpedance, E-ISSN 1891-5469, Vol. 2, s. 72-78Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Activities around applications of Electrical Bioimpedance Spectroscopy (EBIS) have proliferated in the past decade significantly. Most of these activities have been focused in the analysis of the EBIS measurements, which eventually might enable novel applications. In Body Composition Assessment (BCA) the most common analysis approach currently used in EBIS is based on the Cole function, which most often requires curve fitting. One of the most implemented approaches for obtaining the Cole parameters is performed in the impedance plane through the geometrical properties that the Cole function exhibit in such domain as depressed semi-circle. To fit the measured impedance data to a semi-circle in the impedance plane, obtaining the Cole parameters in an indirect and sequential manner has several drawbacks. Applying a Non-Linear Least Square (NLLS) iterative fitting on the spectroscopy measurement, obtains the Cole parameters considering the frequency information contained in the measurement. In this work, from experimental total right side EBIS measurements, the BCA parameters have been obtained to assess the amount and distribution of whole body fluids. The values for the BCA parameters have been obtained using values for the Cole parameters estimated with both approaches: circular fitting on the impedance plane and NLLS impedance-only fitting. The comparison of the values obtained for the BCA parameters with both methods confirms that the NLLS impedance-only is an effective alternative as Cole parameter estimation method in BCA from EBIS measurements. Using the modulus of the Cole function as the model for the fitting would eliminate the need for performing a phase detection in the acquisition process, simplifying the hardware specifications of the measurement instrumentation when implementing a bioimpedance spectrometer.

    Ladda ner fulltext (pdf)
    RUBU-JEB-2011
  • 19.
    Buendia, Ruben
    et al.
    School of Engineering, University of Borås.
    Gil-Pita, Roberto
    Department of Theory of the Signal and Communications, University of Alcala, Madrid, Spain.
    Seoane, Fernando
    KTH, Skolan för teknik och hälsa (STH), Medicinska sensorer, signaler och system (MSSS).
    Cole parameter estimation from total right side electrical bioimpedance spectroscopy measurements: Influence of the number of frequencies and the upper limit2011Ingår i: 2011 ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY (EMBC), 2011, s. 1843-1846Konferensbidrag (Refereegranskat)
    Abstract [en]

    Applications based on measurements of Electrical Bioimpedance Spectroscopy (EBIS) analysis are proliferating. The most spread and known application of EBIS is the non-invasive assessment of body composition. Fitting to the Cole function to obtain the Cole parameters, R<sub>0</sub> and R<sub>&#x221E;</sub>, is the core of the EBIS analysis to obtain the body fluid distribution. An accurate estimation of the Cole parameters is essential for the Body Composition Assessment (BCA) and the estimation process depends on several factors. One of them is the upper frequency limit used for the estimation and the other is the number of measured frequencies in the measurement frequency range. Both of them impose requirements on the measurement hardware, influencing largely in the complexity of the bioimpedance spectrometer. In this work an analysis of the error obtained when estimating the Cole parameters with several frequency ranges and different number of frequencies has been performed. The study has been done on synthetic EBIS data obtained from experimental Total Right Side (TRS) measurements. The results suggest that accurate estimations of R<sub>0</sub> and R<sub>&#x221E;</sub> for BCA measurements can be achieved using much narrower frequency ranges and quite fewer frequencies than electrical bioimpedance spectrometers commercially available nowadays do.

  • 20.
    Buendia, Ruben
    et al.
    KTH, Skolan för teknik och hälsa (STH), Medicinska sensorer, signaler och system (MSSS).
    Seoane, Fernando
    KTH, Skolan för teknik och hälsa (STH), Medicinska sensorer, signaler och system (MSSS).
    Bosacus, I.
    University of Gothenburg.
    Gil-Pita, Roberto
    Department of Theory of the Signal and Communications, University of Alcala, Madrid, Spain.
    Johannsson, G.
    Ellegård, L.
    Lindecrantz, Kaj
    KTH, Skolan för teknik och hälsa (STH), Medicinska sensorer, signaler och system (MSSS).
    Robust approach against capacitive coupling for the estimation of body fluids using clinical bioimpedance spectroscopy measurementsManuskript (preprint) (Övrigt vetenskapligt)
  • 21.
    Buendia, Ruben
    et al.
    School of Engineering, University of Borås, SE-501 90 Borås, Sweden; Department of Signal Theory and Communications, University of Alcala, ES-28871, Madrid, Spain.
    Seoane, Fernando
    School of Engineering, University of Borås, SE-501 90 Borås, Sweden; Department of Signal and Systems, Chalmers University of Technology, SE-41296, Gothenburg, Sweden.
    Gil-Pita, Roberto
    Department of Theory of the Signal and Communications, University of Alcala, Madrid, Spain.
    Experimental validation of a method for removing the capacitive leakage artifact from electrical bioimpedance spectroscopy measurements2010Ingår i: Measurement science and technology, ISSN 0957-0233, E-ISSN 1361-6501, Vol. 21, nr 11Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Often when performing electrical bioimpedance (EBI) spectroscopy measurements, the obtained EBI data present a hook-like deviation, which is most noticeable at high frequencies in the impedance plane. The deviation is due to a capacitive leakage effect caused by the presence of stray capacitances. In addition to the data deviation being remarkably noticeable at high frequencies in the phase and the reactance spectra, the measured EBI is also altered in the resistance and the modulus. If this EBI data deviation is not properly removed, it interferes with subsequent data analysis processes, especially with Cole model-based analyses. In other words, to perform any accurate analysis of the EBI spectroscopy data, the hook deviation must be properly removed. Td compensation is a method used to compensate the hook deviation present in EBI data; it consists of multiplying the obtained spectrum, Z meas (ω), by a complex exponential in the form of exp(–jωTd). Although the method is well known and accepted, Td compensation cannot entirely correct the hook-like deviation; moreover, it lacks solid scientific grounds. In this work, the Td compensation method is revisited, and it is shown that it should not be used to correct the effect of a capacitive leakage; furthermore, a more developed approach for correcting the hook deviation caused by the capacitive leakage is proposed. The method includes a novel correcting expression and a process for selecting the proper values of expressions that are complex and frequency dependent. The correctness of the novel method is validated with the experimental data obtained from measurements from three different EBI applications. The obtained results confirm the sufficiency and feasibility of the correcting method.

    Ladda ner fulltext (pdf)
    RUBU-MST-2010
  • 22.
    Buendia, Ruben
    et al.
    Philips Research Aachen, 52066 Aachen, Weisshausstrafle 2, Germany; School of Engineering, University of Borås, Borås SE-501 90, Allégatan 1, Sweden.
    Seoane, Fernando
    School of Engineering, University of Borås, Borås SE-501 90, Allégatan 1, Sweden.
    Harris, Matthew
    Phillips Research.
    Caffarel, Jeniffer
    Phillips Research.
    Gil-Pita, Roberto
    Department of Theory of the Signal and Communications, University of Alcala, Madrid, Spain.
    Hook Effect correction & resistance-based Cole fitting prior Cole model-based analysis: Experimental validation2010Ingår i: Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC), 2010, IEEE Engineering in Medicine and Biology , 2010, s. 6563-6566Konferensbidrag (Refereegranskat)
    Abstract [en]

    The analysis of measurements of Electrical Bioimpedance (EBI) is on the increase for performing non-invasive assessment of health status and monitoring of pathophysiological mechanisms. EBI measurements might contain measurements artefacts that must be carefully removed prior to any further analysis. Cole model-based analysis is often selected when analysing EBI data and might lead to miss-conclusion if it is applied on data contaminated with measurement artefacts. The recently proposed Correction Function to eliminate the influence of the Hook Effect from EBI data and the fitting to the real part of the Cole model to extract the Cole parameters have been validated on experimental measurements. The obtained results confirm the feasible experimental use of these promising pre-processing tools that might improve the outcome of EBI applications using Cole model-based analysis.

  • 23.
    Buendia, Ruben
    et al.
    KTH, Skolan för teknik och hälsa (STH), Medicinska sensorer, signaler och system (MSSS). University of Alcala, Spain; Chalmers University of Technology, Sweden; University of Boras, Sweden.
    Seoane, Fernando
    KTH, Skolan för teknik och hälsa (STH), Medicinska sensorer, signaler och system (MSSS). University of Boras, Sweden.
    Lindecrantz, Kaj
    KTH, Skolan för teknik och hälsa (STH), Medicinska sensorer, signaler och system (MSSS). University of Boras, Sweden; Karolinska Instituet, Sweden.
    Bosacus, I.
    University of Gothenburg.
    Gil-Pita, Roberto
    Department of Theory of the Signal and Communications, University of Alcala, Madrid, Spain.
    Johannsson, G.
    Ellegård, L.
    Ward, L.
    Estimation of body fluids with bioimpedance spectroscopy: state of the art methods and proposal of novel methods2015Ingår i: Physiological Measurement, ISSN 0967-3334, E-ISSN 1361-6579, Vol. 36, nr 10Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Determination of body fluids is a useful common practice in determination of disease mechanisms and treatments. Bioimpedance spectroscopy (BIS) methods are non-invasive, inexpensive and rapid alternatives to reference methods such as tracer dilution. However, they are indirect and their robustness and validity are unclear. In this article, state of the art methods are reviewed, their drawbacks identified and new methods are proposed. All methods were tested on a clinical database of patients receiving growth hormone replacement therapy. Results indicated that most BIS methods are similarly accurate (e.g. < 0.5 +/- 3.0% mean percentage difference for total body water) for estimation of body fluids. A new model for calculation is proposed that performs equally well for all fluid compartments (total body water, extra-and intracellular water). It is suggested that the main source of error in extracellular water estimation is due to anisotropy, in total body water estimation to the uncertainty associated with intracellular resistivity and in determination of intracellular water a combination of both.

  • 24.
    Buendía López, Rubén
    KTH, Skolan för teknik och hälsa (STH), Medicinska sensorer, signaler och system (MSSS).
    Model Based Enhancement of Bioimpedance Spectroscopy Analysis: Towards Textile Enabled Applications2011Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Several signal processing approaches have been developed to overcome the effect of stray capacitances in Electrical Bioimpedance Spectroscopy (EBIS) measurements. EBIS measurements obtained with textile-enabled instrumentation are more vulnerable to stray capacitances. Currently, the most widespread approach for correcting the effect of stray capacitances in EBIS is the time delay (

    Td) compensation method, which also has several drawbacks. In this study, the Td method is revisited and its limitations and its lack of a scientific basis are demonstrated. To determine better ways to overcome the effect of stray capacitances, a simplified measurement model is proposed that is based on previous models of artefacts in EBIS measurements described in the literature. The model consists of a current divider with a parasitic capacitance (Cpar) in parallel with the load. Cpar creates a pathway for the measurement current to leak away from the load, provoking a capacitive leakage effect. In this thesis, three approaches with different limitations are proposed to overcome the capacitive leakage effect. The first approach estimates Cpar and subtracts it from the measurements, thus finding the load. Cpar can be estimated because the susceptance of biological tissue is null at infinite frequency. Therefore, at high frequencies, the susceptance of the tissue can be neglected, and the slope of the susceptance of the measurement is Cpar. The accuracy of Cpar depends on the maximum frequency measured and the value of Cpar. Therefore, it may not be possible to accurately estimate small values of Cpar in the typical frequency ranges used in EBIS. The second and third approaches use the Cole fitting process to estimate the Cole parameters, which form the basis for most EBIS applications. Because the conductance of the measurement is free from the effect of Cpar, performing Cole fitting on the conductance avoids the effect of Cpar in the fitting process. With a poor skin-electrode contact, this approach may not be sufficiently accurate. The third approach would be to perform the Cole fitting on the modulus with a reduced upper frequency limit because the modulus and the low-medium frequencies are very robust against the effect of artefacts. In this approach, a slight capacitive leakage effect is unavoidable. Since it is common to find tainted measurements, especially among those obtained with textile-enabled instrumentation, it is important to find viable methods to avoid their effect. The three methods studied showed that they could reduce the effect of tainted measurements.

    Ladda ner fulltext (pdf)
    fulltext
    Ladda ner fulltext (pdf)
    fulltext
  • 25.
    Burvall, Anna
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Barrett, Harrison H.
    Myers, Kyle J.
    Dainty, Christopher
    Singular-value decomposition of a tomosynthesis system2010Ingår i: Optics Express, E-ISSN 1094-4087, Vol. 18, nr 20, s. 20699-20711Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Tomosynthesis is an emerging technique with potential to replace mammography, since it gives 3D information at a relatively small increase in dose and cost. We present an analytical singular-value decomposition of a tomosynthesis system, which provides the measurement component of any given object. The method is demonstrated on an example object. The measurement component can be used as a reconstruction of the object, and can also be utilized in future observer studies of tomosynthesis image quality.

  • 26.
    Cai, Huanchen
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Intelligenta system, Tal, musik och hörsel, TMH.
    Ternström, Sten
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Intelligenta system, Tal, musik och hörsel, TMH.
    Mapping Phonation Types by Clustering of Multiple Metrics2022Ingår i: Applied Sciences, ISSN 2076-3417, Vol. 12, nr 23, s. 12092-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    For voice analysis, much work has been undertaken with a multitude of acoustic and electroglottographic metrics. However, few of these have proven to be robustly correlated with physical and physiological phenomena. In particular, all metrics are affected by the fundamental frequency and sound level, making voice assessment sensitive to the recording protocol. It was investigated whether combinations of metrics, acquired over voice maps rather than with individual sustained vowels, can offer a more functional and comprehensive interpretation. For this descriptive, retrospective study, 13 men, 13 women, and 22 children were instructed to phonate on /a/ over their full voice range. Six acoustic and EGG signal features were obtained for every phonatory cycle. An unsupervised voice classification model created feature clusters, which were then displayed on voice maps. It was found that the feature clusters may be readily interpreted in terms of phonation types. For example, the typical intense voice has a high peak EGG derivative, a relatively high contact quotient, low EGG cycle-rate entropy, and a high cepstral peak prominence in the voice signal, all represented by one cluster centroid that is mapped to a given color. In a transition region between the non-contacting and contacting of the vocal folds, the combination of metrics shows a low contact quotient and relatively high entropy, which can be mapped to a different color. Based on this data set, male phonation types could be clustered into up to six categories and female and child types into four. Combining acoustic and EGG metrics resolved more categories than either kind on their own. The inter- and intra-participant distributional features are discussed.

  • 27. Capece, Sabrina
    et al.
    Chiessi, Ester
    Cavalli, Roberta
    Giustetto, Pierangela
    Grishenkov, Dmitry
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik, Medicinsk avbildning.
    Paradossi, Gaio
    A general strategy for obtaining biodegradable polymer shelled microbubbles as theranostic devices2013Ingår i: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, Vol. 49, nr 51, s. 5763-5765Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Fabrication of multifunctional ultrasound contrast agents (UCAs) has been recently addressed by several research groups. A versatile strategy for the synthesis of UCA precursors in the form of biodegradable vesicles with a biocompatible crosslinked polymer shell is described. Upon ultrasound irradiation, acoustic droplet vaporization transforms such particles into microbubbles behaving as UCAs. This proof of concept entails the features of a potential theranostic microdevice.

  • 28. Carlsson, Camilla
    et al.
    Söderqvist, Emil
    KTH, Tidigare Institutioner (före 2005), KTH Syd.
    Brodin, Lars-Åke
    Källner, Göran
    Hultman, Jan
    Elmqvist, Håkan
    Saha, Samir
    Initial experience with a thin single segment pressure and conductance catheter for measurement of left ventricular volume2001Ingår i: Annual Reports of the Research Reactor Institute, Kyoto University, 2001, s. 103-106Konferensbidrag (Refereegranskat)
    Abstract [en]

    Aims: To evaluate a thin and soft multifunctionalcatheter for the simultaneous real time monitoring of leftventricular volume and pressure with special consideration toside elTects such as interference with normal cardiacelectrophysiology.Methods and results: In four pigs, pressure and volumewere simultaneously recorded by using the thin single segmentpressure and conductance catheter. Measurements were doneunder varied cardiac conditions: at baseline, during preloadreduction and afterload Increase. Volumes were calibrated withintracardiac ultrasound measurements. During preloadreduction the pressure and volume decreased as expected. Acautious afterload increase resulted in a corresponding pressureand volume increase, the maximum of the pressure curvechanged from early to late. Both SV and EDV increased. Thevery few arrhythmias were mainly caused by surgicalinterference.Conclusion: The present study demonstrates that our thinsingle segment conductance catheter for the simultaneousmeasurement of LV volume and pressure has a performancethat warrants further development with the goal to make themethod available for human use. In particular, the catheter didnot cause any arrhythmias.

  • 29.
    Chen, Heping
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH). Shanghai Jiao Tong Univ, Sch Biomed Engn, Shanghai, Peoples R China..
    Shi, Yan
    Shanghai Jiao Tong Univ, Sch Biomed Engn, Shanghai, Peoples R China..
    Bo, Bin
    Shanghai Jiao Tong Univ, Sch Biomed Engn, Shanghai, Peoples R China..
    Zhao, Denghui
    Shanghai Jiao Tong Univ, Sch Biomed Engn, Shanghai, Peoples R China..
    Miao, Peng
    Shanghai Jiao Tong Univ, Sch Biomed Engn, Shanghai, Peoples R China..
    Tong, Shanbao
    Shanghai Jiao Tong Univ, Sch Biomed Engn, Shanghai, Peoples R China..
    Wang, Chunliang
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Medicinteknik och hälsosystem, Medicinsk avbildning.
    Real-Time Cerebral Vessel Segmentation in Laser Speckle Contrast Image Based on Unsupervised Domain Adaptation2021Ingår i: Frontiers in Neuroscience, ISSN 1662-4548, E-ISSN 1662-453X, Vol. 15, artikel-id 755198Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Laser speckle contrast imaging (LSCI) is a full-field, high spatiotemporal resolution and low-cost optical technique for measuring blood flow, which has been successfully used for neurovascular imaging. However, due to the low signal-noise ratio and the relatively small sizes, segmenting the cerebral vessels in LSCI has always been a technical challenge. Recently, deep learning has shown its advantages in vascular segmentation. Nonetheless, ground truth by manual labeling is usually required for training the network, which makes it difficult to implement in practice. In this manuscript, we proposed a deep learning-based method for real-time cerebral vessel segmentation of LSCI without ground truth labels, which could be further integrated into intraoperative blood vessel imaging system. Synthetic LSCI images were obtained with a synthesis network from LSCI images and public labeled dataset of Digital Retinal Images for Vessel Extraction, which were then used to train the segmentation network. Using matching strategies to reduce the size discrepancy between retinal images and laser speckle contrast images, we could further significantly improve image synthesis and segmentation performance. In the testing LSCI images of rodent cerebral vessels, the proposed method resulted in a dice similarity coefficient of over 75%.

  • 30.
    Chen, Hongjian
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Medicinteknik och hälsosystem, Medicinsk avbildning.
    Evangelou, Dimitrios
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Medicinteknik och hälsosystem. KTH Royal Inst Technol, Dept Biomed Engn & Hlth Syst, S-14152 Stockholm, Sweden..
    Loskutova, Ksenia
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Medicinteknik och hälsosystem, Medicinsk avbildning.
    Ghorbani, Morteza
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Medicinteknik och hälsosystem, Medicinsk avbildning. Sabanci Univ, Nanotechnol Res & Applicat Ctr, TR-34956 Istanbul, Turkey..
    Grishenkov, Dmitry
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Medicinteknik och hälsosystem, Medicinsk avbildning. Karolinska Inst, Dept Clin Sci Intervent & Technol, S-14152 Stockholm, Sweden.;Karolinska Univ Hosp, Dept Clin Physiol, S-17177 Stockholm, Sweden..
    On the Development of a Novel Contrast Pulse Sequence for Polymer-Shelled Microbubbles2021Ingår i: IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control, ISSN 0885-3010, E-ISSN 1525-8955, Vol. 68, nr 5, s. 1569-1579Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Contrast agents are routinely used in ultrasound examinations. Nonlinear ultrasound imaging techniques have been developed over decades to enhance the contrast between the tissue and the blood pool after the injection of ultrasound contrast agents (UCAs). In this study, we introduce a new contrast pulse sequence, CPS4. The CPS4 combines pulse inversion (PI), subharmonic (SH), and ultraharmonic (UH) techniques to remove propagation distortion while capturing the unique SH and UH responses from UCAs. The novel CPS4 and conventional PI, SH, and UH techniques were used to detect the presence of a research-grade, thick-shell, polymer microbubble in a tissue-mimicking flow phantom. The contrast-to-tissue ratios (CTRs) obtained from the applications of all techniques were compared. The results show that the highest CTR of approximately 16 dB was obtained using CPS4, which was superior to the individual reference techniques: PI, SH, and UH techniques, in all scenarios considered in this study.

  • 31.
    Chen, Yawen
    et al.
    KTH, Skolan för datavetenskap och kommunikation (CSC), Centra, Parallelldatorcentrum, PDC.
    Shen, Hong
    Zhang, Haibo
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik.
    A Novel P-shape Tessellation Approach on Double-Loop Networks2009Ingår i: 2009 IEEE INTERNATIONAL SYMPOSIUM ON IT IN MEDICINE & EDUCATION, VOLS 1 AND 2, PROCEEDINGS, NEW YORK: IEEE , 2009, s. 507-511Konferensbidrag (Refereegranskat)
    Abstract [en]

    Double loop computer networks are widely used in the design and implementation of local area networks and parallel processing architectures. However the embedding problems on double-loop networks have not been well studied due to the complexity of double-loop networks. Since the traditional L-shape, designed to compute the diameter of double-loop networks, is not efficient to solve embedding problems, we propose a novel tessellation approach to partition the geometric plane of double-loop networks into a set of parallelogram shaped tiles, called P-shape. Our proposed tessellation technique, P-shape, is a useful theoretical tool for embedding meshes on double-loop networks, and can be extended to analyze other problems as a bridge between regular graphs and double-loop networks.

  • 32. Cheng, Yirui
    et al.
    Qu, Xiangyun
    Dong, Zhaonan
    Zeng, Qingyu
    Ma, Xueqing
    Jia, Yunli
    Li, Ruochen
    Jiang, Xiaoxu
    Williams, Cecilia
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Proteinvetenskap, Cellulär och klinisk proteomik.
    Wang, Tao
    Xia, Weiliang
    Comparison of serum exosome isolation methods on co-precipitated free microRNAs.2020Ingår i: PeerJ, E-ISSN 2167-8359, Vol. 8, artikel-id e9434Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Background: Exosomes are nano-sized extracellular vesicles containing different biomolecules such as proteins and microRNAs (miRNAs) that mediate intercellular communication. Recently, numerous studies have reported the important functions of exosomal miRNAs in disease development and the potential clinical application as diagnostic biomarkers. Up to now, the most commonly used methods to extract exosomes are ultracentrifugation (UC) and precipitation-based commercial kit (e.g., ExoQuick). Generally, both UC and ExoQuick method could co-isolate contaminating proteins along with exosomes, with the UC method yielding even purer exosomes than ExoQuick. However, the comparison of these two methods on co-precipitated free miRNAs is still unknown.

    Methods: In this study, we isolated exosomes from the human serum with exogenously added cel-miR-39 by UC and ExoQuick and compared the proportion of cel-miR-39 co-precipitated with exosomes extracted by these two methods.

    Results: Using exogenous cel-miR-39 as free miRNAs in serum, we concluded that ExoQuick co-isolates a small proportion of free miRNAs while UC hardly precipitates any free miRNAs. We also found that incubation at 37 °C for 1 h could decrease the proportion of free miRNAs, and exosomal miRNAs like miR-126 and miR-152 also decreased when RNase A was used. In conclusion, our findings provide essential information about the details of serum exosome isolation methods for further research on exosomal miRNAs.

  • 33. Comellas, E.
    et al.
    Gasser, T. Christian
    KTH, Skolan för teknikvetenskap (SCI), Hållfasthetslära (Inst.).
    Bellomo, F. J.
    Oller, S.
    A homeostatic-driven turnover remodelling constitutive model for healing in soft tissues2016Ingår i: Journal of the Royal Society Interface, ISSN 1742-5689, E-ISSN 1742-5662, Vol. 13, nr 116, artikel-id 20151081Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Remodelling of soft biological tissue is characterized by interacting biochemical and biomechanical events, which change the tissue's microstructure, and, consequently, its macroscopic mechanical properties. Remodelling is a well-defined stage of the healing process, and aims at recovering or repairing the injured extracellular matrix. Like other physiological processes, remodelling is thought to be driven by homeostasis, i.e. it tends to re-establish the properties of the uninjured tissue. However, homeostasis may never be reached, such that remodelling may also appear as a continuous pathological transformation of diseased tissues during aneurysm expansion, for example. A simple constitutive model for soft biological tissues that regards remodelling as homeostatic-driven turnover is developed. Specifically, the recoverable effective tissue damage, whose rate is the sum of a mechanical damage rate and a healing rate, serves as a scalar internal thermodynamic variable. In order to integrate the biochemical and biomechanical aspects of remodelling, the healing rate is, on the one hand, driven by mechanical stimuli, but, on the other hand, subjected to simple metabolic constraints. The proposed model is formulated in accordance with continuum damage mechanics within an open-system thermodynamics framework. The numerical implementation in an in-house finite-element code is described, particularized for Ogden hyperelasticity. Numerical examples illustrate the basic constitutive characteristics of the model and demonstrate its potential in representing aspects of remodelling of soft tissues. Simulation results are verified for their plausibility, but also validated against reported experimental data.

  • 34.
    Decrop, Deborah
    et al.
    KU Leuven, Belgium.
    Pardon, Gaspard
    KTH, Skolan för elektro- och systemteknik (EES), Mikro- och nanosystemteknik.
    Kokalj, Tadej
    KU Leuven, Belgium.
    Robert, Puers
    KU Leuven, Belgium.
    Haraldsson, Tommy
    KTH, Skolan för elektro- och systemteknik (EES), Mikro- och nanosystemteknik.
    Lammertyn, Jeroen
    KU Leuven, Belgium.
    van der Wijngaart, Wouter
    KTH, Skolan för elektro- och systemteknik (EES), Mikro- och nanosystemteknik.
    Single-step manufacturing of femtoliter microwell arrays in a novel surface energy mimicking polymer2015Ingår i: 18th International Conference on Solid-State Sensors, Actuators and Microsystems (IEEE TRANSDUCER 2015), IEEE , 2015Konferensbidrag (Refereegranskat)
    Abstract [en]

    We report a novel polymer material formulation and stamp-molding technique that enable rapid single-step manufacturing of hydrophilic-in-hydrophobic microwell arrays. We developed a modified thiol-ene-epoxy polymer (mOSTE+) formulation that mimics the surface energy of its mold during polymerization. The polymer inherits the surface energy from the mold through molecular self-assembly, in which functional monomers self-assemble at the interface between the liquid prepolymer and the mold surface. Combining this novel mOSTE+ material with a stamp-molding process leads to simultaneous surface energy mimicking and micro-structuring. This method was used to manufacture microwells with hydrophilic bottom and hydrophobic sidewall, depressed in a surrounding hydrophobic surface. The microwell arrays were successfully tested for the self-assembly of 62’000 femtoliter-droplets. Such femtoliter droplet arrays are useful for, e.g., digital ELISA and single cell/molecule analysis applications.

  • 35.
    Dehlinger, Aurelie
    et al.
    Tech Univ Berlin, Inst Opt & Atomare Phys, Hardenbergstr 36, D-10623 Berlin, Germany.;Berlin Lab Innovat Xray Technol BLiX, Hardenbergstr 36, D-10623 Berlin, Germany..
    Seim, Christian
    Tech Univ Berlin, Inst Opt & Atomare Phys, Hardenbergstr 36, D-10623 Berlin, Germany.;Berlin Lab Innovat Xray Technol BLiX, Hardenbergstr 36, D-10623 Berlin, Germany..
    Stiel, Holger
    Berlin Lab Innovat Xray Technol BLiX, Hardenbergstr 36, D-10623 Berlin, Germany.;Forschungsverbund Berlin eV, Max Born Inst MBI, Max Born Str 2A, D-12489 Berlin, Germany..
    Twamley, Shailey
    Charite Univ Med Berlin, Campus Mitte,Charitepl 1, D-10117 Berlin, Germany.;Humboldt Univ, Freie Univ Berlin, Campus Mitte,Charitepl 1, D-10117 Berlin, Germany.;Berlin Inst Hlth, Med Klin Kardiol & Angiol, Campus Mitte,Charitepl 1, D-10117 Berlin, Germany.;DZHK German Ctr Cardiovasc Res, Partner Site Berlin,Charitepl 1, D-10117 Berlin, Germany..
    Ludwig, Antje
    Charite Univ Med Berlin, Campus Mitte,Charitepl 1, D-10117 Berlin, Germany.;Humboldt Univ, Freie Univ Berlin, Campus Mitte,Charitepl 1, D-10117 Berlin, Germany.;Berlin Inst Hlth, Med Klin Kardiol & Angiol, Campus Mitte,Charitepl 1, D-10117 Berlin, Germany.;DZHK German Ctr Cardiovasc Res, Partner Site Berlin,Charitepl 1, D-10117 Berlin, Germany.;Charite, Charitepl 1, D-10117 Berlin, Germany.;Humboldt Univ, Freie Univ Berlin, Charitepl 1, D-10117 Berlin, Germany.;Berlin Inst Hlth, Radiol Klin, Charitepl 1, D-10117 Berlin, Germany..
    Kördel, Mikael
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Groetzsch, Daniel
    Tech Univ Berlin, Inst Opt & Atomare Phys, Hardenbergstr 36, D-10623 Berlin, Germany.;Berlin Lab Innovat Xray Technol BLiX, Hardenbergstr 36, D-10623 Berlin, Germany..
    Rehbein, Stefan
    Mat & Energie GmbH, Helmholtz Zentrum Berlin, Wilhelm Conrad Rontgen Campus,Albert Einstein St, D-12489 Berlin, Germany..
    Kanngiesser, Birgit
    Tech Univ Berlin, Inst Opt & Atomare Phys, Hardenbergstr 36, D-10623 Berlin, Germany.;Berlin Lab Innovat Xray Technol BLiX, Hardenbergstr 36, D-10623 Berlin, Germany..
    Laboratory Soft X-Ray Microscopy with an Integrated Visible-Light Microscope-Correlative Workflow for Faster 3D Cell Imaging2020Ingår i: Microscopy and Microanalysis, ISSN 1431-9276, E-ISSN 1435-8115, Vol. 26, nr 6, s. 1124-1132Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Laboratory transmission soft X-ray microscopy (L-TXM) has emerged as a complementary tool to synchrotron-based TXM and high-resolution biomedical 3D imaging in general in recent years. However, two major operational challenges in L-TXM still need to be addressed: a small field of view and a potentially misaligned rotation stage. As it is not possible to alter the magnification during operation, the field of view in L-TXM is usually limited to a few tens of micrometers. This complicates locating areas and objects of interest in the sample. Additionally, if the rotation axis of the sample stage cannot be adjusted prior to the experiments, an efficient workflow for tomographic imaging cannot be established, as refocusing and sample repositioning will become necessary after each recorded projection. Both these limitations have been overcome with the integration of a visible-light microscope (VLM) into the L-TXM system. Here, we describe the calibration procedure of the goniometer sample stage and the integrated VLM and present the resulting 3D imaging of a test sample. In addition, utilizing this newly integrated VLM, the extracellular matrix of cryofixed THP-1 cells (human acute monocytic leukemia cells) was visualized by L-TXM for the first time in the context of an ongoing biomedical research project.

  • 36.
    Ekelund, Emil
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Medicinteknik och hälsosystem.
    LactateStat: Wearable Electronics and Software for Real-Time Lactate Monitoring in Sweat2021Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Laktat är en viktig biomarkör inom idrott och konceptet laktattröskel är en av de bästa indikatorerna för uthållighet hos en idrottsutövare. Men för att mäta laktattröskeln krävs en invasiv metod som går ut på att man tar ett blodprov. Begränsningarna med denna metod är bland annat att idrottsutövningen måste stoppas för att ta ett blodprov och att man inte får realtidsåterkoppling.

    I stället kan en liten och icke-invasiv bärbar biosensor användas för att mäta laktatkoncentrationen i svett. Sensorn genererar en elektrisk ström beroende på laktatkoncentrationen i svetten och en enhet som kallas potentiostat måste därför användas för att mäta denna ström. Tillgängliga potentiostater är dock inte lämpliga för användning inom sport där formfaktor, batteritid och trådlös kommunikation är viktigt. Denna avhandling har som syfte att lösa detta genom att utveckla en bärbar enhet och mjukvara som kan användas för att mäta laktatkoncentrationen i svett i realtid under träning.

    Utvecklingsprocessen bestod av bestämning av specifikationer, framtagning av en prototyp och noggrann laboratorie- och kroppstestning.

    Som resultat presenterades en banbrytande bärbar enhet och mjukvara som kan mäta laktat i realtid i svett under träning. Enheten, som kallades LactateStat, var 58mm * 55mm * 13mm, den aktiva strömförbrukningen var 7.8mA, den bästa mätupplösningen för ström var 0.5 nA, detektionsgränsen var 0.45 nA och det maximala mätområdet för ström var ca. 750 μA.

    LactateStat är en av de första i sitt slag och ger en bas för framtida utvecklingsarbete eftersom hårdvaru-, programvaru- och mjukvaruresurserna tillhandahålls som öppen källkod. 

    Ladda ner fulltext (pdf)
    fulltext
  • 37.
    Eriksson, Magnus G.
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Mekatronik.
    Flemmer, Henrik
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Mekatronik.
    Wikander, Jan
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Mekatronik.
    Haptic Simulation of the Milling Process in Temporal Bone Operations2005Ingår i: Medicine Meets Virtual Reality 13: The Magical Next Becomes the Medical Now, IOS Press, 2005, Vol. 111, s. 133-136Konferensbidrag (Refereegranskat)
    Abstract [en]

    A VR-simulation system for educating surgeons of the temporal bone milling processes is presented in this paper. E. g. the milling process that occurs during the removal of certain cancer tumors in the brain. The research project is recently started up and this paper is an introduction to the bone milling simulation topic. We present how the graphical rendering of the temporal bone is done. Acquired data are managed using the Marching cubes algorithm to perform a visual representation. A re-production of iso-surfaces will represent the material removal occurred during the milling process. Force models are discussed and will be implemented in the H3D API, which is used to control the virtual simulation and collision detection. Equipment, implementation and future work are also presented in the paper.

  • 38.
    Eriksson, Martin
    et al.
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik.
    Halvorsen, Kjartan A.
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik.
    Gullstrand, Lennart
    Immediate effect of visual and auditory feedback to control the running mechanics of well-trained athletes2011Ingår i: Journal of Sports Sciences, ISSN 0264-0414, E-ISSN 1466-447X, Vol. 29, nr 3, s. 253-262Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The correlation between mechanical factors of running and running economy as measured by metabolic cost is a subject of much interest in the study of locomotion. However, no change in running technique has been shown to result in an immediate improvement in running economy on an intra-individual basis. To evaluate the effect of a modified running technique, it is probably necessary that the individual trains with the new technique for a longer period using a feedback system to control the new kinematics. In this study, we examine the feasibility of using visual and auditory feedback to adapt running technique according to a simplistic model of the mechanical cost of running. The model considers only the mechanical work against gravity, which is the product of the magnitude of the vertical displacement of the runner's centre of mass and the step-frequency. In the experiments reported here, 18 trained runners, running at 16km center dot h-1 on a treadmill, were given feedback on these parameters together with indicated target levels. In almost all cases, the runners were able to adjust their technique accordingly.

  • 39.
    Etcheverry Cabrera, Sebastian
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Advanced all-fiber optofluidic devices2017Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Significant technological advances of the last years have been possible by developments in Optofluidics, which is a field that deals with the integration of optics and microfluidics into single devices.

    The work described in this thesis is based on five scientific publications related to the use of fiber optic technology to build integrated optofluidic devices. The first three publications are within the field of life-science and point towards in-vivo and point-of-care applications, whereas the last two publications cover the study and the use of plasmonic nanoparticles for electrical modulation of light.

    Aiming at developing useful tools for in-vivo biological applications, the first publication consists of designing and testing a functional optical fiber for real-time monitoring and selective collection of fluorescent microparticles. This probe relies on a microstructured optical fiber with a hole along its cladding, which is used to selectively aspirate individual particles of interest once their fluorescence signal is detected. On the same line of research, the second publication contemplates the fabrication of a fiber probe that traps single microparticles and allows for remote detection of their optical properties. This probe is also based on a microstructured fiber that enables particle trapping by fluidic forces. The third publication addresses the development of an all-fiber miniaturized flow cytometer for point-of-care applications. This system can analyze, with excellent accuracy and sensitivity, up to 2500 cells per second by measuring their fluorescence and scattering signal. A novel microfluidic technique, called Elasto-inertial microfluidics, is employed for aligning the cells into a single-stream to optimize detection and throughput.

    The fourth publication involves the experimental and theoretical study of the electrical-induced alignment of plasmonic gold nanorods in suspension and its applicability to control light transmission. This study is done by using an all-fiber optofluidic device, based on a liquid-core fiber, which facilitates the interaction of light, electric fields, and liquid suspensions. Results show that nanorods can be aligned in microseconds, providing a much better performance than liquid-crystal devices. Finally, the fifth publication consists of an upgrade of the previous device by integrating four electrodes in the cladding of the liquid-core fiber. This improvement enables nanosecond response time and the possibility of digitally switching nanorods between two orthogonal aligned states, overcoming the limitation of slow thermal relaxation.

    The work presented here shows that optofluidics based on optical fibers is a robust and convenient platform, as well as a promising direction for the developing of novel instruments in fields such as life-science, non-linear optics, plasmonic, and sensing.

    Ladda ner fulltext (pdf)
    fulltext
  • 40. Falkmer, Torbjern
    et al.
    Dahlman, Joakim
    Dukic, Tania
    Bjällmark, Anna
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik.
    Larsson, Matilda
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik.
    Fixation identification in centroid versus start-point modes using eye-tracking data2008Ingår i: Perceptual and Motor Skills, ISSN 0031-5125, E-ISSN 1558-688X, Vol. 106, nr 3, s. 710-724Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Fixation-identification algorithms, needed for analyses of eye movements, may typically be separated into three categories, viz. (i) velocity-based algorithms, (ii) area-based algorithms, and (iii) dispersion-based algorithms. Dispersion-based algorithms are commonly used but this application introduces some difficulties, one being optimization. Basically, there are two modes to reach this goal of optimization, viz., the start-point mode and the centroid mode. The aim of the present study was to compare and evaluate these two dispersion-based algorithms. Manual inspections were made of 1,400 fixations in each mode. Odds ratios showed that by using the centroid mode for fixation detection, a valid fixation is 2.86 times more likely to be identified than by using the start-point mode. Moreover, the algorithm based on centroid mode dispersion showed a good interpretation speed, accuracy, robustness, and ease of implementation, as well as adequate parameter settings.

  • 41.
    Fernández Schrunder, Alejandro
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elektronik och inbyggda system.
    Huang, Yu-Kai
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elektronik och inbyggda system.
    Rodriguez, Saul
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elektronik och inbyggda system.
    Rusu, Ana
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elektronik och inbyggda system.
    A Real-Time Muscle Fatigue Detection System Based on Multi-Frequency EIM and sEMG for Effective NMES2024Ingår i: IEEE Sensors Journal, ISSN 1530-437X, E-ISSN 1558-1748, s. 1-1Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Neuromuscular electrical stimulation (NMES) is a self-directed home based therapeutic tool in early rehabilitation for musculoskeletal (MSK) conditions. However, the effectiveness of traditional NMES is fundamentally constrained by muscle fatigue. To address this limitation, this work proposes a detection system, which simultaneously records multifrequency electrical impedance myography (EIM) and surface electromyography(sEMG) in real time for time-frequency analysis of muscle activation, contraction, and fatigue. To demonstrate the ability to monitor these muscle physiological states, two experiments involving weightless and weighted dynamic contractions of the biceps brachii muscle were performed. Results from these experiments show synchronous changes in sEMG and EIM spectra during contractions, and clear trends in sEMG’s mean power frequency (MPF) and EIM spectra with fatigue progression. Additionally, the configurable 4-channel NMES has been electrically evaluated for clinical use, demonstrating the feasibility of the proposed system for closed-loop stimulation. This work showcases the potential of sEMG and multi-frequency EIM to enhance the effectiveness of NMES for MSK conditions by capturing the behavior of distinct mechanisms of muscle fatigue.

    Ladda ner fulltext (pdf)
    fulltext
  • 42.
    Ferreira, Javier
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik. Högskolan i Borås.
    Modular textile-enabled bioimpedance system for personalized health monitoring applications2017Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    A growing number of factors, including costs, technological advancements, ageing populations, and medical errors, are leading industrialized countries to invest in research on alternative solutions to improve their health-care systems and increase patients’ quality of life. Personal health systems (PHS) examplify the use of information and communication technologies that enable a paradigm shift from the traditional hospital-centered healthcare delivery model toward a preventive and person-centered approach. PHS offer the means to monitor a patient’s health using wearable, portable or implantable systems that offer ubiquitous, unobtrusive biodata

    acquisition, allowing remote monitoring of treatment and access to the patient’s status. Electrical bioimpedance (EBI) technology is non-invasive, quick and relatively affordable technique that can be used for assessing and monitoring different health conditions, e.g., body composition assessments for nutrition. When combined with state-of-the-art advances in sensors and textiles, EBI technologies are fostering the implementation of wearable bioimpedance monitors that use functional garments for personalized healthcare applications. This research work is

    focused on the development of wearable EBI-based monitoring systems for ubiquitous health monitoring applications. The monitoring systems are built upon portable monitoring instrumentation and custom-made textile electrode garments.

    Portable EBI-based monitors have been developed using the latest material technology and advances in system-on-chip technology. For instance, a portable EBI spectrometer has been validated against a commercial spectrometer for total body composition assessment using functional textile electrode garments. The development of wearable EBI-based monitoring units using functional garments and dry textile electrodes for body composition assessment and respiratory monitoring has been shown to be a feasible approach. The availability of these measurement systems indicates progress toward the real implementation of personalized healthcare systems.

    Ladda ner fulltext (pdf)
    PhDThesisJFG
  • 43.
    Ferreira, Javier
    et al.
    School of Engineering, University of Borås, Sweden.
    Seoane, Fernando
    School of Engineering, University of Borås, Sweden;Department of Signal & Systems, Chalmers University of Technology, SE-41296, Gothenburg, SWEDEN.
    Ansede, Antonio
    Technical University of Catalonia.
    Bragós, Ramon
    Technical University of Catalonia.
    AD5933-based spectrometer for electrical bioimpedance applications2010Konferensbidrag (Refereegranskat)
    Abstract [en]

    To build an Electrical Bioimpedance (EBI) spectrometer using the Impedance Measurement System-On-Chip AD5933 together with a 4-Electrode Analog Front End (4E-AFE) has been proven practicable. Such small measurement devices can make possible several new applications of EBI technology, especially when combined with functional textiles, which can enable wearable applications for personal health and home monitoring. After the implementation and functional validation of the 4E-AFE-enabled spectrometer, the next natural step is to validate for which EBI applications the 4E-AFE-enabled system is suitable. To test the applicability of this novel spectrometer on several EBI applications, 2R1C equivalent models have been experimentally obtained and impedance spectroscopy measurements have been performed with the system under study and with the SFB7 EBI spectrometer manufactured by ImpediMed. The 2R1C circuit parameters have been estimated with the BioImp software from the spectra obtained with both EBI spectrometers and the estimated values have been compared with the original values used in each circuit model implementation. The obtained results indicated that the 4E-AFE-enabled system cannot beat the performance of the SFB7 in accuracy but it performs better in preciseness. In any case the overall performance indicates that the 4E-AFE-enabled system can perform spectroscopy measurements in the frequency range from 5 to 100 kHz.

    Ladda ner fulltext (pdf)
    JAVI-ICEBI-2010
  • 44.
    Fornara, Andrea
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Qin, Jian
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Laurent, Sophie
    University of Mons.
    Muller, Robert
    University of Mons.
    Muhammed, Mamoun
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Bifunctional polylactide coated iron oxide nanoparticles for drug delivery and MRI contrast enhancementIngår i: Advanced Materials, ISSN 0935-9648, E-ISSN 1521-4095Artikel i tidskrift (Övrigt vetenskapligt)
  • 45. Fornell, Anna
    et al.
    Nilsson, Johan
    Jonsson, Linus
    Periyannan Rajeswari, Prem Kumar
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Proteinvetenskap, Nanobioteknologi.
    Jönsson, Håkan
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Proteinvetenskap, Nanobioteknologi.
    Tenje, Maria
    Particle enrichment in droplet acoustofluidics2016Ingår i: Micronano System Workshop (MSW 2016), Lund, Sweden, May 17-18 2016, 2016Konferensbidrag (Refereegranskat)
  • 46.
    Fredenberg, Erik
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Medicinsk bildfysik.
    Spectral Mammography with X-Ray Optics and a Photon-Counting Detector2009Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Early detection is vital to successfully treating breast cancer, and mammography screening is the most efficient and wide-spread method to reach this goal. Imaging low-contrast targets, while minimizing the radiation exposure to a large population is, however, a major challenge. Optimizing the image quality per unit radiation dose is therefore essential. In this thesis, two optimization schemes with respect to x-ray photon energy have been investigated: filtering the incident spectrum with refractive x-ray optics (spectral shaping), and utilizing the transmitted spectrum with energy-resolved photon-counting detectors (spectral imaging).

    Two types of x-ray lenses were experimentally characterized, and modeled using ray tracing, field propagation, and geometrical optics. Spectral shaping reduced dose approximately 20% compared to an absorption-filtered reference system with the same signal-to-noise ratio, scan time, and spatial resolution. In addition, a focusing pre-object collimator based on the same type of optics reduced divergence of the radiation and improved photon economy by about 50%.

    A photon-counting silicon detector was investigated in terms of energy resolution and its feasibility for spectral imaging. Contrast-enhanced tumor imaging with a system based on the detector was characterized and optimized with a model that took anatomical noise into account. Improvement in an ideal-observer detectability index by a factor of 2 to 8 over that obtained by conventional absorption imaging was found for different levels of anatomical noise and breast density. Increased conspicuity was confirmed by experiment. Further, the model was extended to include imaging of unenhanced lesions. Detectability of microcalcifications increased no more than a few percent, whereas the ability to detect large tumors might improve on the order of 50% despite the low attenuation difference between glandular and cancerous tissue. It is clear that inclusion of anatomical noise and imaging task in spectral optimization may yield completely different results than an analysis based solely on quantum noise.

    Ladda ner fulltext (pdf)
    FULLTEXT01
  • 47.
    Fredenberg, Erik
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Medicinsk bildfysik.
    Cederström, Björn
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Medicinsk bildfysik.
    Danielsson, Mats
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Medicinsk bildfysik.
    Energy filtering with x-ray lenses: Optimization for photon-counting mammography2010Ingår i: Radiation Protection Dosimetry, ISSN 0144-8420, E-ISSN 1742-3406, Vol. 139, s. 339-342Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Chromatic properties of the multi-prism and prism-array x-ray lenses (MPL and PAL) can potentially be utilized for efficient energy filtering and dose reduction in mammography. The line-shaped foci of the lenses are optimal for coupling to photon-counting silicon strip detectors in a scanning system. A theoretical model was developed and used to investigate the benefit of two lenses compared to an absorption-filtered reference system. The dose reduction of the MPL filter was 15% compared to the reference system at matching scan time, and the spatial resolution was higher. The dose of the PAL-filtered system was found to be 20% lower than for the reference system at equal scan time and resolution, and only 20% higher than for a monochromatic beam. An investigation of some practical issues remains, including the feasibility of brilliant-enough x-ray sources and manufacturing of a polymer PAL.

    Ladda ner fulltext (pdf)
    fulltext
  • 48.
    Fredenberg, Erik
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Medicinsk bildfysik. KTH, Skolan för bioteknologi (BIO), Centra, Albanova VinnExcellence Center for Protein Technology, ProNova.
    Cederström, Björn
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Medicinsk bildfysik. KTH, Skolan för bioteknologi (BIO), Centra, Albanova VinnExcellence Center for Protein Technology, ProNova.
    Nillius, Peter
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Medicinsk bildfysik. KTH, Skolan för bioteknologi (BIO), Centra, Albanova VinnExcellence Center for Protein Technology, ProNova.
    Ribbing, Carolina
    Uppsala Univ..
    Karlsson, Staffan
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Medicinsk bildfysik. KTH, Skolan för bioteknologi (BIO), Centra, Albanova VinnExcellence Center for Protein Technology, ProNova.
    Danielsson, Mats
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Medicinsk bildfysik. KTH, Skolan för bioteknologi (BIO), Centra, Albanova VinnExcellence Center for Protein Technology, ProNova.
    A low-absorption x-ray energy filter for small-scale applications2009Ingår i: Optics Express, E-ISSN 1094-4087, Vol. 17, nr 14, s. 11388-11398Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We present an experimental and theoretical evaluation of an x-ray energy filter based on the chromatic properties of a prism-array lens (PAL). It is intended for small-scale applications such as medical imaging. The PAL approximates a Fresnel lens and allows for high efficiency compared to filters based on ordinary refractive lenses, however at the cost of a lower energy resolution. Geometrical optics was found to provide a good approximation for the performance of a flawless lens, but a field-propagation model was used for quantitative predictions. The model predicted a 0.29 ΔE/E energy resolution and an intensity gain of 6.5 for a silicon PAL at 23.5 keV. Measurements with an x-ray tube showed good agreement with the model in energy resolution and peak energy, but a blurred focal line contributed to a 29% gain reduction. We believe the blurring to be caused mainly by lens imperfections, in particular at the periphery of the lens.

  • 49.
    Fredenberg, Erik
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Medicinsk bildfysik.
    Cederström, Björn
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Medicinsk bildfysik.
    Åslund, Magnus
    Sectra Mamea AB, Smidesvägen 5, SE‐171 41 Solna, Sweden.
    Nillius, Peter
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Medicinsk bildfysik.
    Danielsson, Mats
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Medicinsk bildfysik.
    An efficient pre-object collimator based on an x-ray lens2009Ingår i: Medical physics (Lancaster), ISSN 0094-2405, Vol. 36, nr 2, s. 626-633Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A multiprism lens (MPL) is a refractive x-ray lens with one-dimensional focusing properties. If used as a pre-object collimator in a scanning system for medical x-ray imaging, it reduces the divergence of the radiation and improves on photon economy compared to a slit collimator. Potential advantages include shorter acquisition times, a reduced tube loading, or improved resolution. We present the first images acquired with a MPL in a prototype for a scanning mammography system. The lens showed a gain of flux of 1.32 compared to a slit collimator at equal resolution, or a gain in resolution of 1.31–1.44 at equal flux. We expect the gain of flux in a clinical setup with an optimized MPL and a custom-made absorption filter to reach 1.67, or 1.45–1.54 gain in resolution.

    Ladda ner fulltext (pdf)
    fulltext
  • 50.
    Fredenberg, Erik
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Medicinsk bildfysik.
    Cederström, Björn
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Medicinsk bildfysik.
    Åslund, Magnus
    Ribbing, Carolina
    Uppsala universitet.
    Danielsson, Mats
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Medicinsk bildfysik.
    A Tunable Energy Filter for Medical X-Ray Imaging2008Ingår i: X-Ray Optics and Instrumentation, ISSN 1687-7632, Vol. 2008Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A multiprism lens (MPL) is a refractive X-ray lens, and its chromatic properties can be employed in an energy filtering setup to obtain a narrow tunable X-ray spectrum. We present the first evaluation of such a filter for medical X-ray imaging. The experimental setup yields a 6.6 gain of flux at 20 keV, and we demonstrate tunability by altering the energy spectrum to center also around 17 and 23 keV. All measurements are found to agree well with ray-tracing and a proposed geometrical model. Compared to a model mammography system with absorption filtering, the experimental MPL filter reduces dose 13–25% for 3–7 cm breasts if the spectrum is centered around the optimal energy. Additionally, the resolution is improved 2.5 times for a 5 cm breast. The scan time is increased 3 times but can be reduced with a slightly decreased energy filtering and resolution.

123456 1 - 50 av 268
RefereraExporteraLänk till träfflistan
Permanent länk
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf