Página 1 dos resultados de 266 itens digitais encontrados em 0.010 segundos

Alteração do tempo de transito epididimario : implicações no perfil proteico e outros parametros espermaticos; Alteration of epididymal trasit time : implications on the proteic proteic rofile and other sperm parameters

Carla Dal Bianco Fernandez
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 15/09/2006 PT
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26.03%
O epidídimo é um órgão do sistema reprodutor masculino, onde os espermatozóides passam pelo processo de maturação, adquirindo motilidade e capacidade fértil. O tempo de trânsito espermático pelo epidídimo (número de dias necessários para os espermatozóides serem transportados pelo órgão) parece ter um papel importante na maturação dos espermatozóides, e uma alteração desse tempo pode prejudicar o processo. Trabalhos da literatura mostram que a exposição de ratos machos a substâncias estrogênicas, como o dietilestilbestrol (DES), afeta o trato reprodutor masculino e provoca uma aceleração do tempo de trânsito dos espermatozóides pelo epidídimo, comprometendo a fertilidade nestes animais. O objetivo do presente trabalho foi avaliar a influência da alteração do tempo de trânsito dos espermatozóides no epidídimo sobre parâmetros espermáticos e fertilidade em ratos, bem como o papel da testosterona nestas alterações. Para tanto, dois modelos experimentais foram utilizados: o DES foi administrado para acelerar o tempo de trânsito espermático nos ratos, e a guanetidina, para retardá-lo, através da simpatectomia química na genitália interna masculina. Ratos machos adultos, da variedade Sprague-Dawley...

Welcome to the European society for artificial organs-international federation for artificial organs joint congress in Porto, Portugal

Reis, R. L.
Fonte: Wichtig Publicador: Wichtig
Tipo: Outros
Publicado em 10/11/2011 ENG
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26.06%

Is there correlation between the turbulent eddies size and mechanical hemolysis ?

Pinotti,Marcos
Fonte: The Brazilian Society of Mechanical Sciences Publicador: The Brazilian Society of Mechanical Sciences
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2000 EN
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Hemolytic profile of an artificial device chronically implanted in the cardiovascular system may represent the difference between the success and failure in its long-term performance. Last decades have witnessed efforts on the development of methods capable of predicting red blood cell damage in artificial organs. However, all of them have had limited success to predict hemolysis. The primary cause of this problem is that such models do not take into consideration structures of turbulent flow. The present paper demonstrates that microscopic measurable occurrences of the turbulent flow may be linked to red blood cell trauma. This study suggests that if the smallest turbulent eddies dimension is under 10 m m hemolysis is not dependent on the exposure time and the red blood cells damage depends only on the dissipation of the turbulent energy in the erythrocyte membrane. The analysis reported here opens the possibility of mapping the flow field in artificial assist devices based on the smallest eddy length scales. This is a promising new trend and should be considered in the designing requirements of the next generations of artificial organs.

Cells involved in the immune response. XXVIII. the cellular composition of the lymphoid organs in the normal outbred rabbit.

Richter, M; De La Noue, C; Hamdy, H
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /07/1975 EN
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Horse anti-rabbit spleen cell antiserum was obtained by the intravenous immunization of horses with rabbit spleen cells. The antisera obtained were analysed for their lymphocytotoxic activity with respect to the lymphoid cells of the different lymphoid organs prior to and following absorption with the different lymphoid cells. The results have been integrated with those obtained in previous investigations and an all-embracing concept of the interrelationship of the lymphoid cells in the different lymphoid organs in the rabbit has emerged. The distinction between the heretofore considered central lymphoid organs (bone marrow and thymus) and peripheral lymphoid organs (spleen, lymph node and appendix) has been blurred by the finding that, at least in the rabbit, appendix cells possess specific antigen markers and participate in cell-mediated immune reactions in vitro and the observation that the spleen also has a central lymphoid function in the generation of cells in vivo capable of carrying out a cell-mediated immune reaction in vitro. It is concluded that the distinction of central and peripheral lymphoid function may be an artificial one in that it may reflect a function of the particular organ in only one of the many different types of immune reactions and that it should not influence the investigator in the elucidation of the cellular mechanisms participating in the mediation of the different immune responses.

Distant touch hydrodynamic imaging with an artificial lateral line

Yang, Yingchen; Chen, Jack; Engel, Jonathan; Pandya, Saunvit; Chen, Nannan; Tucker, Craig; Coombs, Sheryl; Jones, Douglas L.; Liu, Chang
Fonte: National Academy of Sciences Publicador: National Academy of Sciences
Tipo: Artigo de Revista Científica
EN
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Nearly all underwater vehicles and surface ships today use sonar and vision for imaging and navigation. However, sonar and vision systems face various limitations, e.g., sonar blind zones, dark or murky environments, etc. Evolved over millions of years, fish use the lateral line, a distributed linear array of flow sensing organs, for underwater hydrodynamic imaging and information extraction. We demonstrate here a proof-of-concept artificial lateral line system. It enables a distant touch hydrodynamic imaging capability to critically augment sonar and vision systems. We show that the artificial lateral line can successfully perform dipole source localization and hydrodynamic wake detection. The development of the artificial lateral line is aimed at fundamentally enhancing human ability to detect, navigate, and survive in the underwater environment.

ARTIFICIAL MAINTENANCE MEDIA FOR CELL AND ORGAN CULTIVATION : II. THE CULTIVATION OF ORGANS IN ARTIFICIAL MEDIA

Baker, Lillian E.; Carrel, Alexis
Fonte: The Rockefeller University Press Publicador: The Rockefeller University Press
Tipo: Artigo de Revista Científica
Publicado em 30/06/1939 EN
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Experiments have been described in which organs cultivated in the Lindbergh apparatus have been kept alive in artificial media for periods ranging from 3 days to 3 weeks, with life continuing in portions of some glands for from 35 to 62 days. The media used varied in composition from very simple and inexpensive ones in which some serum was used to a rather complex medium containing only that negligible amount of serum that is necessary as a solvent for vitamin A. The experiments performed demonstrate that artificial media can be used for organ cultivation, thus making it possible to study the behavior of human organs; to control the composition of the media at will; and to reduce the cost of experimentation.

Environmental control of sepalness and petalness in perianth organs of waterlilies: a new Mosaic Theory for the evolutionary origin of a differentiated perianth

Warner, Kate A.; Rudall, Paula J.; Frohlich, Michael W.
Fonte: Oxford University Press Publicador: Oxford University Press
Tipo: Artigo de Revista Científica
EN
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The conventional concept of an ‘undifferentiated perianth’, implying that all perianth organs of a flower are alike, obscures the fact that individual perianth organs are sometimes differentiated into sepaloid and petaloid regions, as in the early-divergent angiosperms Nuphar, Nymphaea, and Schisandra. In the waterlilies Nuphar and Nymphaea, sepaloid regions closely coincide with regions of the perianth that were exposed when the flower was in bud, whereas petaloid regions occur in covered regions, suggesting that their development is at least partly controlled by the environment of the developing tepal. Green and colourful areas differ from each other in trichome density and presence of papillae, features that often distinguish sepals and petals. Field experiments to test whether artificial exposure can induce sepalness in the inner tepals showed that development of sepaloid patches is initiated by exposure, at least in the waterlily species examined. Although light is an important environmental cue, other important factors include an absence of surface contact. Our interpretation contradicts the unspoken rule that ‘sepal’ and ‘petal’ must refer to whole organs. We propose a novel theory (the Mosaic theory), in which the distinction between sepalness and petalness evolved early in angiosperm history...

The MIXTA-like Transcription factor MYB16 is a major regulator of cuticle formation in vegetative organs

Oshima, Yoshimi; Mitsuda, Nobutaka
Fonte: Landes Bioscience Publicador: Landes Bioscience
Tipo: Artigo de Revista Científica
Publicado em 29/10/2013 EN
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Cuticle secreted on the surface of the epidermis of aerial organs protects plants from the external environment. We recently found that Arabidopsis MIXTA-like R2R3-MYB family members MYB16 and MYB106 regulate cuticle formation in reproductive organs and trichomes. However, the artificial miRNA (amiRNA)-mediated knockdown plants showed no clear phenotypic abnormality in vegetative tissues. In this study, we used RNA interference (RNAi) targeting MYB16 to produce plants with reduced expression of both MYB16 and MYB106. The rosette leaves of RNAi plants showed more severe permeable cuticle phenotypes than the myb106 mutants expressing the MYB16 amiRNA in the previous study. The RNAi plants also showed reduced expression of cuticle biosynthesis genes LACERATA and ECERIFERUM1. By contrast, expression of a gain-of-function MYB16 construct induced over-accumulation of waxy substances on leaves. These results suggest that MYB16 functions as a major regulator of cuticle formation in vegetative organs, in addition to its effect in reproductive organs and trichomes.

FDA Premarket Regulation of Tissue-Engineered Replacement Parts for Humans

Leon, Doraliz
Fonte: Harvard University Publicador: Harvard University
Tipo: Paper (for course/seminar/workshop)
EN_US
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This paper is a description of tissue-engineered products, their potential for replacing conventional approaches to missing or failing tissues and organs, and FDA’s ongoing efforts to develop a comprehensive and uniform scheme for regulating them.

BE.441 Biomaterials-Tissue Interactions, Fall 2003; Biomaterials-Tissue Interactions

Spector, Myron; Yannas, Ioannis V.
Fonte: MIT - Massachusetts Institute of Technology Publicador: MIT - Massachusetts Institute of Technology
EN-US
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Principles of materials science and cell biology underlying the design of medical implants, artificial organs, and matrices for tissue engineering. Methods for biomaterials surface characterization and analysis of protein adsorption on biomaterials. Molecular and cellular interactions with biomaterials are analyzed in terms of unit cell processes, such as matrix synthesis, degradation, and contraction. Mechanisms underlying wound healing and tissue remodeling following implantation in various organs. Tissue and organ regeneration. Design of implants and prostheses based on control of biomaterials-tissue interactions. Comparative analysis of intact, biodegradable, and bioreplaceable implants by reference to case studies. Criteria for restoration of physiological function for tissues and organs.

2.782J / 3.961J / 20.451J / HST.524J Design of Medical Devices and Implants, Spring 2003; Design of Medical Devices and Implants

Yannas, Ioannis V.; Spector, Myron
Fonte: MIT - Massachusetts Institute of Technology Publicador: MIT - Massachusetts Institute of Technology
EN-US
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Solution of clinical problems by use of implants and other medical devices. Systematic use of cell-matrix control volumes. The role of stress analysis in the design process. Anatomic fit: shape and size of implants. Selection of biomaterials. Instrumentation for surgical implantation procedures. Preclinical testing for safety and efficacy: risk/benefit ratio assessment. Evaluation of clinical performance: design of clinical trials. Project materials drawn from orthopedic devices, soft tissue implants, artificial organs, and dental implants.

Systematic review of safety and effectiveness of an artificial bowel sphincter for faecal incontinence

Mundy, L.; Merlin, T.; Maddern, G.; Hiller, J.
Fonte: John Wiley & Sons Ltd Publicador: John Wiley & Sons Ltd
Tipo: Artigo de Revista Científica
Publicado em //2004 EN
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BACKGROUND: The aim was to determine the safety and effectiveness of the implantation of an artificial bowel sphincter for the treatment of severe faecal incontinence. METHOD: Medical bibliographic databases, the internet and reference lists were searched from January 1966 to January 2003. Only the lowest level of evidence was available for inclusion in this systematic review. Case series and case reports were selected to assess safety, whereas only case series were selected to assess effectiveness. RESULTS: Fourteen studies met the inclusion criteria. A number of safety issues were reported, including high explantation rates, and rates of adverse events owing to infection, device malfunction, ulceration and pain. Results in published reports were not analysed on an intention-to-treat basis. Continence, quality of life and manometry scores were reported for patients with a functioning device at the end of follow-up. These patients experienced a significant improvement in their level of continence. As no outcome data were presented for those with a non-functioning or explanted device, it is possible that such patients may have a worsened degree of incontinence or decreased quality of life. CONCLUSION: Implantation of an artificial bowel sphincter is of uncertain benefit and may possibly harm many patients. Patient selection is therefore critical and should be enhanced by higher-quality research.; L. Mundy...

Konservierung von Herzen in einem in situ Protektionsverfahren : funktioneller, laborchemischer und histomorphologischer Vergleich der künstlichen Sauerstoffträger Perfluorocarbone mit University of Wisconsin Lösung im Großtiermodell; Heart preservation by in situ perfusion : Functional, chemical and histomorphological comparison of artificial oxygen carrier perfluorocarbons with University of Wisconsin solution in a big animal model

Pappas, Ioannis
Fonte: Universidade de Tubinga Publicador: Universidade de Tubinga
Tipo: Dissertação
DE_DE
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Organknappheit stellt einen der größten limitierenden Faktoren für die Transplantationsmedizin dar. Eine Erweiterung des Spenderpools wäre über die Hinzunahme von Organen von kreislauftoten Spendern möglich. Weiterhin wäre eine Optimierung der Organprotektion über die Entwicklung verbesserter Protektionlösungen möglich. Perfluorocarbone stellen in dieser Hinsicht als künstliche Sauerstoffträger einen interessanten Ansatzpunkt dar. Ziel dieser Studie war es zu zeigen, ob es möglich ist Herzen von kreislauftoten Spendern über ein geeignetes Kathetersystem in situ zu protektionieren und darüber hinaus zu untersuchen wie sich die Herzen nach der Protektion mit Perfluorocarbone im Vergleich zu Herzen, die mittels der University of Wisconsin Lösung protektioniert wurden, im isolierten Herzmodell verhalten. Hierfür wurden 16 Schweine untersucht. Diese wurden in 2 Gruppen (UW Gruppe und PFC Gruppe) von je 8 Tieren aufgeteilt. Über ein speziell konzipiertes Kathetersystem, das operativ am eröffneten Thorax und an den präparierten Halsgefäßen eingebracht wurde, wurde nach Eintreten des Kreislaufsillstands die Kardioprotektion gestartet und über 60 min kontinuierlich in situ durchgeführt. Nach der Entnahme der Herzen wurden diese kontinuierlich am Kreislaufmodell mit der Kardioprotektionslösung perfundiert...

Avaliação e aperfeiçoamento de uma bomba de sangue centrífuga implantável ápice ventricular para assistência cardíaca; Evaluation and improvement of an apico-aortic centrifugal blood pump for cardiac assist

Bruno Utiyama da Silva
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 17/09/2012 PT
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35.92%
Neste trabalho, foi realizado um estudo experimental de uma Bomba de Sangue Ápice Ventricular (BSAV) para sua análise como um dispositivo de assistência ventricular. Este estudo faz parte do desenvolvimento desta bomba e serviu como fundamentação na evolução do projeto. A BSAV é uma bomba de sangue centrífuga de fluxo contínuo, para ser utilizada como dispositivo de assistência ventricular em pacientes com doenças cardíacas crônicas. Foi realizado um estudo de posicionamento anatômico, onde a bomba foi implantada em um coração de um porco e não foram encontrados indícios de possíveis danos aos tecidos e órgãos circunvizinhos. Em seguida, foi feito um ensaio experimental, onde foi comparado o desempenho de protótipos com características distintas, visando sua otimização em relação ao desempenho hidrodinâmico. Também foi realizado um estudo para avaliação do trauma as células do sangue causado pela ação da bomba, no qual os resultados mostraram um baixo dano as células. A seguir, foi feito estudo com um protótipo conectado em um simulador cardiovascular híbrido (matemático e físico), onde este protótipo às condições simuladas de um sistema cardiovascular com insuficiência cardíaca. Com a BSAV conectada ao sistema obteve-se...

Functional tooth restoration by next-generation bio-hybrid implant as a bio-hybrid artificial organ replacement therapy

Oshima, Masamitsu; Inoue, Kaoru; Nakajima, Kei; Tachikawa, Tetsuhiko; Yamazaki, Hiromichi; Isobe, Tomohide; Sugawara, Ayaka; Ogawa, Miho; Tanaka, Chie; Saito, Masahiro; Kasugai, Shohei; Takano-Yamamoto, Teruko; Inoue, Takashi; Tezuka, Katsunari; Kuboki, T
Fonte: Nature Publishing Group Publicador: Nature Publishing Group
Tipo: Artigo de Revista Científica
Publicado em 13/08/2014 EN
Relevância na Pesquisa
36.21%
Bio-hybrid artificial organs are an attractive concept to restore organ function through precise biological cooperation with surrounding tissues in vivo. However, in bio-hybrid artificial organs, an artificial organ with fibrous connective tissues, including muscles, tendons and ligaments, has not been developed. Here, we have enveloped with embryonic dental follicle tissue around a HA-coated dental implant, and transplanted into the lower first molar region of a murine tooth-loss model. We successfully developed a novel fibrous connected tooth implant using a HA-coated dental implant and dental follicle stem cells as a bio-hybrid organ. This bio-hybrid implant restored physiological functions, including bone remodelling, regeneration of severe bone-defect and responsiveness to noxious stimuli, through regeneration with periodontal tissues, such as periodontal ligament and cementum. Thus, this study represents the potential for a next-generation bio-hybrid implant for tooth loss as a future bio-hybrid artificial organ replacement therapy.

Simulation Techniques and Prosthetic Approach Towards Biologically Efficient Artificial Sense Organs- An Overview

Neogi, Biswarup; Ghosal, Soumya; Mukherjee, Soumyajit; Das, Achintya; Tibarewala, D. N.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 07/11/2011
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An overview of the applications of control theory to prosthetic sense organs including the senses of vision, taste and odor is being presented in this paper. Simulation aspect nowadays has been the centre of research in the field of prosthesis. There have been various successful applications of prosthetic organs, in case of natural biological organs dis-functioning patients. Simulation aspects and control modeling are indispensible for knowing system performance, and to generate an original approach of artificial organs. This overview focuses mainly on control techniques, by far a theoretical overview and fusion of artificial sense organs trying to mimic the efficacies of biologically active sensory organs. Keywords: virtual reality, prosthetic vision, artificial; Comment: 12 Pages

Global metabolic optimality in the structure of the coronary arteries

Keelan, Jonathan; Chung, Emma M. L.; Hague, James P.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
35.92%
The structure of the large coronary arteries is both heritable and reasonably consistent between individuals, but the extent to which this results from evolutionary pressure towards an energy-efficient, globally-optimal, structure is unknown. We present an algorithm for the determination of an energetically globally optimal arterial tree in arbitrary tissue geometries. We demonstrate through application of the algorithm that it is possible to generate in-silico vasculatures that closely match porcine anatomical data on all length scales. We therefore conclude that evolutionary pressure has resulted in a near globally optimal structure of the larger coronary arteries. We also examine the effect of changing length scales, predicting that the structures of the coronary arteries can change from a meandering form for small animals to very straight vessels for large animals. The method presented here is not limited to hearts, and represents a major advance in modeling the arterial vasculature, that could have important applications for medical imaging analysis and the design of artificial organs.

A Brief Comparison Between Available Bio-printing Methods

Bakhshinejad, Ali; D'Souza, Roshan M
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 17/02/2015
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The scarcity of organs for transplant has led to large waiting lists of very sick patients. In drug development, the time required for human trials greatly increases the time to market. Drug companies are searching for alternative environments where the in-vivo conditions can be closely replicated. Both these problems could be addressed by manufacturing artificial human tissue. Recently, researchers in tissue engineering have developed tissue generation methods based on 3-D printing to fabricate artificial human tissue. Broadly, these methods could be classified as laser-assisted and laser free. The former have very fine spatial resolutions (10s of $\mu$m) but suffer from slow speed ( $< 10^2$ drops per second). The later have lower spatial resolutions (100s of $\mu$ m) but are very fast (up to $5\times 10^3$ drops per second). In this paper we review state-of-the-art methods in each of these classes and provide a comparison based on reported resolution, printing speed, cell density and cell viability.

Design of a continuous flow centrifugal pediatric ventricular assist device

Throckmorton, A.; Wood, H.; Day, Steven; Song, X.; Click, P.; Allaire, P.; Olsen, D.
Fonte: Wichtig Editore: International journal of artificial organs Publicador: Wichtig Editore: International journal of artificial organs
Tipo: Artigo de Revista Científica
EN_US
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Thousands of pediatric patients suffering from cardiomyopathy or single ventricular physiologies secondary to debilitating heart defects may benefit from long-term mechanical circulatory support due to the limited number of donor hearts available. This article presents the initial design of a fully implantable centrifugal pediatric ventricular assist device (PVAD) for 2 to 12 year olds. Conventional pump design equations, including a nondimensional scaling approach, enabled performance estimations of smaller scale versions (25 mm and 35 mm impeller diameters) of our adult support VAD. Based on this estimated performance, a computational model of the PVAD with a 35 mm impeller diameter was generated. Employing computational fluid dynamics (CFD) software, the flow paths through the PVAD and overall performance were analyzed for steady state flow conditions. The numerical simulations involved flow rates of 2 to 5 LPM for rotational speeds of 2750 to 3250 RPM and incorporated a k-e fluid turbulence model with a logarithmic wall function to characterize near-wall flow conditions. The CFD results indicated best efficiency points ranging from 25% to 28%, which correlate well with typical values of blood pumps. The results further demonstrated that the pump could deliver 2 to 5 LPM at 70 to 95 mmHg for desired physiologic conditions in resting 2 to 12 year olds. Scalar stress levels remained below 300 Pa...

A Prototype HeartQuest ventricular assist device for particle image velocimetry measurements

Day, Steven; McDaniel, James; Wood, Houston; Allaire, Paul; Song, Xinwei; Lemire, Phillip; Miles, Scott
Fonte: Artificial organs Publicador: Artificial organs
Tipo: Abstract
EN_US
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The objective of this study is to fully characterize the flow within the HeartQuest ventricular assist device (VAD), a magnetically levitated centrifugal VAD, using particle image velocimetry (PIV) to identify regions of potential high shear or stagnation and validate and refine computational models of the flow. An acrylic model of the pump was designed and constructed to allow optical access into all interior regions of the pump. The geometry of the exterior housing and the use of a novel working fluid make quantitative measurements of velocity within the exit volute, blade passage, cut-water, blade tip clearance, and pump inlet possible. Highly accurate velocity measurements using particle PIV have been made in one region (the inlet elbow), and measurements in the other critical regions of the pump will be made. These measurements are used for investigation of regions with potential for hemolysis resulting from high shear stress or with potential for thrombosis caused by recirculation or stagnation. Quantitative velocity data are also needed for comparison with computational fluid dynamics (CFD) models of the VAD. In this study, experiments have again proven to be an essential complement to CFD for thorough investigations of the flow inside the pump.; Journal of Artificial organs article. Please see http://www3.interscience.wiley.com/journal/118914196/abstract for more information.